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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /macros/generic/witharrows/witharrows.dtx
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+% \iffalse meta-comment
+%
+% Copyright (C) 2017-2019 by F. Pantigny
+% -----------------------------------
+%
+% This file may be distributed and/or modified under the
+% conditions of the LaTeX Project Public License, either version 1.3
+% of this license or (at your option) any later version.
+% The latest version of this license is in:
+%
+% http://www.latex-project.org/lppl.txt
+%
+% and version 1.3 or later is part of all distributions of LaTeX
+% version 2005/12/01 or later.
+%
+% \fi
+% \iffalse
+\def\myfileversion{2.0}
+\def\myfiledate{2019/07/30}
+%
+%
+%<*batchfile>
+\begingroup
+\input l3docstrip.tex
+\keepsilent
+\usedir{tex/latex/witharrows}
+\preamble
+
+Copyright (C) 2017-2019 by F. Pantigny
+-----------------------------------
+
+This file may be distributed and/or modified under the
+conditions of the LaTeX Project Public License, either version 1.3
+of this license or (at your option) any later version.
+The latest version of this license is in:
+
+http://www.latex-project.org/lppl.txt
+
+and version 1.3 or later is part of all distributions of LaTeX
+version 2005/12/01 or later.
+
+\endpreamble
+\askforoverwritefalse
+\endgroup
+%</batchfile>
+%
+%<*driver>
+\documentclass[dvipsnames]{l3doc}% dvipsnames is for xcolor (loaded by Tikz, loaded by witharrows)
+\usepackage{xltxtra}
+\usepackage[xetex]{geometry}
+\geometry{left=2.8cm,right=2.8cm,top=2.5cm,bottom=2.5cm,papersize={21cm,29.7cm}}
+\usepackage[footnotehyper]{witharrows}
+\usetikzlibrary{calc}
+\usepackage{mathtools}
+\usepackage{amssymb}
+\usepackage[only,llbracket,rrbracket]{stmaryrd}
+\usepackage{varwidth}
+\NewDocumentEnvironment {scope} {} {} {}
+\def\interitem{\vskip 7mm plus 2 mm minus 3mm}
+\def\emphase{\bgroup\color{RoyalPurple}\let\next=}
+\fvset{commandchars=\~\#\@,formatcom={\color{gray}}}
+\DeclareMathOperator{\re}{Re}
+\skip \footins = 2 \bigskipamount
+\parindent 0pt
+\DisableCrossrefs
+\begin{document}
+\DocInput{witharrows.dtx}
+\end{document}
+%</driver>
+% \fi
+% \VerbatimFootnotes
+% \title{The package \pkg{witharrows} for plain-TeX and LaTeX\thanks{This document corresponds to the
+% version~\myfileversion\space of \pkg{witharrows}, at the date
+% of~\myfiledate.}} \author{F. Pantigny \\ \texttt{fpantigny@wanadoo.fr}}
+%
+% \maketitle
+%
+% \hypersetup{
+% pdfinfo = {
+% Title = { The extension 'witharrows' },
+% Subject = { A extension for plain-TeX and LaTeX} ,
+% Author = { F. Pantigny }
+% }
+% }
+%
+%
+% \begin{abstract}
+% The LaTeX package \pkg{witharrows} provides environments |{WithArrows}| and
+% |{DispWithArrows}| similar to the environments |{aligned}| and |{align}| of
+% \pkg{amsmath} but with the possibility to draw arrows on the right side of the
+% alignment. These arrows are usually used to give explanations concerning the
+% mathematical calculus presented.
+% \end{abstract}
+%
+%
+% \vspace{1cm} In this document, we describe the LaTeX extension
+% \pkg{witharrows} (however, \pkg{witharrows} can also be used with plain-TeX:
+% see p.~\pageref{plain-TeX}). This package can be used with |xelatex|,
+% |lualatex|, |pdflatex| but also by the classical workflow
+% |latex|-|dvips|-|ps2pdf| (or Adobe Distiller). This package loads the packages
+% \pkg{expl3}, \pkg{l3keys2e}, \pkg{xparse}, \pkg{tikz} and the Tikz libraries
+% \pkg{arrows.meta} and \pkg{bending}. The arrows are drawn with Tikz and that's
+% why several compilations may be necessary.
+%
+% \bigskip
+% This package provides an environment |{WithArrows}| to construct alignments of
+% equations with arrows for the explanations on the right side:
+%
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 ~emphase#\Arrow{we expand}@ \\
+% & = a^2 + 2a + 1 % don't put \\ here
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+%
+%
+% \medskip
+% The arrow has been drawn with the command |\Arrow| on the row from which it
+% starts. The command |\Arrow| must be used in the second column (the best way
+% is to put it at the end of the second cell of the row as in the previous
+% example).
+%
+% \medskip
+% The environment |{WithArrows}| bears similarities with the environment
+% |{aligned}| of \pkg{amsmath} (and |mathtools|). The extension \pkg{witharrows}
+% also provides an environment |{DispWithArrows}| which is similar to the
+% environment |{align}| of \pkg{amsmath}: cf. p. \pageref{DispWithArrows}.
+%
+%
+% \section{Options for the shape of the arrows}
+%
+% The command |\Arrow| has several options. These options can be put between
+% square brackets, before, or after the mandatory argument.
+%
+% The option |jump| gives the number\footnote{It's not possible to give a
+% non-positive value to |jump|. See below (p.~\pageref{Backwards}) the way to
+% draw an arrow which goes backwards.} of rows the arrow must jump (the default
+% value is, of course,~$1$).
+%
+%
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2 \Arrow[~emphase#jump=2@]{we expand} \\
+% & = (a+b)^2 + 2(a+b) +1 \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2 \Arrow[jump=1+1]{we expand} \\
+% & = (a+b)^2 + 2(a+b) +1 \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+%
+% \interitem
+% It's possible to put several arrows which start from the same row.
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2 ~emphase#\Arrow{}\Arrow{}[jump=2]@ \\
+% & = (a+b)^2 + 2(a+b) +1 \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2 \Arrow{}\Arrow{}[jump=2] \\
+% & = (a+b)^2 + 2(a+b) +1 \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+%
+% \interitem
+% The option |xoffset| shifts the arrow to the right (we usually don't want the
+% arrows to be stucked on the text). The default value of |xoffset| is $3$~mm.
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2
+% \Arrow[~emphase#xoffset=1cm@]{with \texttt{xoffset=1cm}} \\
+% & = (a+b)^2 + 2(a+b) +1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2
+% \Arrow[xoffset=1cm]{with \texttt{xoffset=1cm}} \\
+% & = (a+b)^2 + 2(a+b) +1
+% \end{WithArrows}$
+%
+%
+% \interitem
+% The arrows are drawn with Tikz. That's why the command |\Arrow| has an option
+% |tikz| which can be used to give to the arrow (in fact, the command |\path| of
+% Tikz) the options proposed by Tikz for such an arrow. The following example
+% gives an thick arrow.
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[~emphase#tikz=thick@]{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[tikz=thick]{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+% \interitem
+% It's also possible to change the arrowheads. For example, we can draw an arrow
+% which goes backwards with the Tikz option~|<-|.
+% \label{Backwards}
+%
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow~emphase#[tikz=<-]@{we factorize} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[tikz=<-]{we factorize} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+% \interitem
+% It's also possible to suppress both tips of the arrow with the Tikz option
+% ``|-|''.
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[~emphase#tikz=-@]{very classical} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[tikz=-]{very classical} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+% \interitem
+% In order to have straight arrows instead of curved ones, we must use the Tikz
+% option ``|bend left = 0|''.
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow~emphase#[tikz={bend left=0}]@{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[tikz={bend left=0}]{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+% \smallskip
+% In fact, it's possible to change more drastically the shape or the arrows with
+% the option |tikz-code| (presented p.~\pageref{tikz-code}).
+%
+% \interitem
+% It's possible to use the Tikz option ``|text width|'' to control the width of
+% the text associated to the arrow.\footnote{It's possible to avoid the
+% hyphenations of the words with the option ``|align = flush left|'' of Tikz.}
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2
+% \Arrow[jump=2,~emphase#tikz={text width=5.3cm}@]{We have done...} \\
+% & = (a+b)^2 + 2(a+b) +1 \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = \bigl((a+b)+1\bigr)^2
+% \Arrow[jump=2,tikz={text width=5.3cm}]{We have done a two-stages expansion but
+% it would have been clever
+% to expand with the multinomial theorem.} \\
+% & = (a+b)^2 + 2(a+b) +1 \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% In the environments |{DispWithArrows}| and |{DispWithArrows*}|, there is an
+% option |wrap-lines|. With this option, the lines of the labels are
+% automatically wrapped on the right: see p.~\pageref{wrap-lines}.
+%
+% \interitem
+% If we want to change the font of the text associated to the arrow, we can, of
+% course, put a command like |\bfseries|, |\large| or |\sffamily| at the
+% beginning of the text. But, by default, the texts are composed with a
+% combination of |\small| and |\itshape|. When adding |\bfseries| at the
+% beginning of the text, we won't suppress the |\small| and the |\itshape| and
+% we will consequently have a text in a bold, italic and small font.
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{~emphase#\bfseries@ we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{\bfseries we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+% \interitem
+% It's possible to put commands |\\| in the text to force new lines\footnote{By
+% default, this is not possible in a Tikz node. However, in \pkg{witharrows},
+% the nodes are created with the option |align=left|, and, thus, it becomes
+% possible.}. However, if we put a |\\| , a command of font placed in the
+% beginning of the text will have effect only until the first command |\\| (like
+% in an environment |{tabular}|). That's why Tikz gives an option |font| to
+% modify the font of the whole text. Nevertheless, if we use the option
+% |tikz={font={\bfseries}}|, the default specification of |\small| and
+% |\itshape| will be overwritten.
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[~emphase#tikz={font={\bfseries}}@]{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow[tikz={font={\bfseries}}]{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+% \medskip
+% If we want exactly the same result as previously, we have to give to the
+% option |font| the value |\itshape\small\bfseries|.
+%
+%
+% \interitem
+% The options can be given directly between square brackets to the environment
+% |{WithArrows}|. There must be no space between the |\begin{WithArrows}| and
+% the opening bracket (|[|) of the options of the environment. Such options
+% apply to all the arrows of the environment.\footnote{They also apply to the
+% nested environments |{WithArrows}| (with the logical exceptions of
+% |interline|, |code-before| and |code-after|).}
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}[~emphase#tikz=blue@]
+% A & = \bigl((a+b)+1\bigr)^2 \Arrow{first expansion.} \\
+% & = (a+b)^2 + 2(a+b) +1 \Arrow{second expansion.} \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}[tikz=blue]
+% A & = \bigl((a+b)+1\bigr)^2 \Arrow{first expansion.} \\
+% & = (a+b)^2 + 2(a+b) +1 \Arrow{second expansion.} \\
+% & = a^2 + 2ab + b^2 + 2a + 2b +1
+% \end{WithArrows}$
+%
+%
+% \interitem
+% The environment |{WithArrows}| has an option |displaystyle|. With this option,
+% all the elements are composed in |\displaystyle| (like in an environment
+% |{aligned}| of \pkg{amsmath}).
+%
+% \medskip
+% Without the option |displaystyle|:
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% \int_0^1 (x+1)^2 dx
+% & = \int_0^1 (x^2+2x+1) dx
+% \Arrow{linearity of integration} \\
+% & = \int_0^1 x^2 dx + 2 \int_0^1 x dx + \int_0^1 dx \\
+% & = \frac13 + 2\frac12 + 1 \\
+% & = \frac73
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% \int_0^1 (x+1)^2 dx
+% & = \int_0^1 (x^2+2x+1) dx
+% \Arrow{linearity of integration} \\
+% & = \int_0^1 x^2 dx + 2 \int_0^1 x dx + \int_0^1 dx \\
+% & = \frac13 + 2\frac12 + 1 \\
+% & = \frac73
+% \end{WithArrows}$
+%
+%
+% \medskip
+% The same example with the option |displaystyle|:\par\nobreak
+%
+% $\begin{WithArrows}[displaystyle]
+% \int_0^1 (x+1)^2 dx
+% & = \int_0^1 (x^2+2x+1) dx
+% \Arrow{linearity of integration} \\
+% & = \int_0^1 x^2 dx + 2 \int_0^1 x dx + \int_0^1 dx \\
+% & = \frac13 + 2\frac12 + 1 \\
+% & = \frac73
+% \end{WithArrows}$
+%
+%
+%
+% \interitem
+% Almost all the options can also be set at the document level with the command
+% |\WithArrowsOptions|. In this case, the scope of the declarations is the
+% current TeX group (these declarations are ``semi-global''). For example, if we
+% want all the environments |{WithArrows}| composed in |\displaystyle| with blue
+% arrows, we can write
+% |\WithArrowsOptions{displaystyle,tikz=blue}|.\footnote{It's also possible to
+% configure \pkg{witharrows} by modifying the Tikz style |WithArrows/arrow|
+% which is the style used by \pkg{witharrows} when drawing an arrow. For
+% example, to have the labels in blue with roman (upright) types, one can use
+% the following instruction:
+% |\tikzset{WithArrows/arrow/.append style = {blue,font = {}}}|.}
+%
+% \begin{Verbatim}
+% ~emphase#\WithArrowsOptions{displaystyle,tikz=blue}@
+% $\begin{WithArrows}
+% \sum_{i=1}^n (x_i+1)^2
+% & = \sum_{i=1}^n (x_i^2+2x_i+1) \Arrow{by linearity}\\
+% & = \sum_{i=1}^n x_i^2 + 2\sum_{i=1}^nx_i+ n
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% \begin{scope}
+% \WithArrowsOptions{displaystyle,tikz=blue}
+% $\begin{WithArrows}
+% \sum_{i=1}^n (x_i+1)^2
+% & = \sum_{i=1}^n (x_i^2+2x_i+1) \Arrow{by linearity}\\
+% & = \sum_{i=1}^n x_i^2 + 2\sum_{i=1}^nx_i+ n
+% \end{WithArrows}$
+% \end{scope}
+%
+%
+% \interitem
+% The command |\Arrow| is recognized only in the environments |{WithArrows}|. If
+% we have a command |\Arrow| previously defined, it's possible to go on using it
+% outside the environments |{WithArrows}|.
+%
+% However, a previouly defined command |\Arrow| may still be useful in an
+% environment |{WithArrows}|. If we want to use it in such an environment, it's
+% possible to change the name of the command |\Arrow| of the package
+% \pkg{witharrows}: there is an option |command-name|\footnote{For historical
+% reasons, there is an alias for this option: |CommandName|.} for this purpose.
+% The new name of the command must be given to the option \emph{without} the
+% leading backslash.
+% %
+% \begin{Verbatim}
+% \NewDocumentCommand {\Arrow} {} {\longmapsto}
+% $\begin{WithArrows}[~emphase#command-name=Explanation@]
+% f & = \bigl(x \Arrow (x+1)^2\bigr)
+% ~emphase#\Explanation{we work directly on fonctions}@\\
+% & = \bigl(x \Arrow x^2+2x+1\bigr)
+% \end{WithArrows}$
+% \end{Verbatim}
+% %
+% \begin{scope}
+% \NewDocumentCommand {\Arrow} {} {\longmapsto}
+% $\begin{WithArrows}[command-name=Explanation]
+% f & = \bigl(x \Arrow (x+1)^2\bigr)
+% \Explanation{we work directly on fonctions}\\
+% & = \bigl(x \Arrow x^2+2x+1\bigr)
+% \end{WithArrows}$
+% \end{scope}
+%
+%
+% \interitem
+% The environment |{WithArrows}| provides also two options |code-before| and
+% |code-after|\footnote{For historical reasons, there are aliases for these
+% options: |CodeBefore| and |CodeAfter|.} for LaTeX code that will be executed
+% at the beginning and at the end of the environment. These options are not
+% designed to be hooks (they are available only at the environment level and
+% they do not apply to the nested environments).
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}[~emphase#code-before = \color{blue}@]
+% A & = (a+b)^2 \Arrow{we expand} \\
+% & = a^2 + 2ab + b^2
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}[code-before = \color{blue}]
+% A & = (a+b)^2 \Arrow{we expand} \\
+% & = a^2 + 2ab + b^2
+% \end{WithArrows}$
+%
+% \medskip
+% Special commands are available in |code-after|: a command |\WithArrowsNbLines|
+% which gives the number of lines (=rows) of the current environment (this is a
+% command and not a counter), a special form of the command |\Arrow| and the
+% command |\MultiArrow|: these commands are described in the section concerning
+% the nested environments, p.~\pageref{NestedEnv}.
+%
+% \section{Numbers of columns}
+%
+% So far, we have used the environment |{WithArrows}| with two columns. However,
+% it's possible to use the environment with an arbitrary number of columns with
+% the option |format|. The value given to this option is like the preamble of an
+% environment |{array}|, that is to say a sequence of letters |r|, |c| and |l|.
+% The default value of the option |format| is, in fact, |rl|.
+%
+% \bigskip
+% For exemple, if we want only one column left-aligned, we use the option |format=l|.
+% \begin{Verbatim}
+% $\begin{WithArrows}[~emphase#format = l@]
+% f(x) \ge g(x) \Arrow{by squaring both sides} \\
+% f(x)^2 \ge g(x)^2 \Arrow{by moving to left side} \\
+% f(x)^2 - g(x)^2 \ge 0
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}[format = l]
+% f(x) \ge g(x) \Arrow{by squaring both sides} \\
+% f(x)^2 \ge g(x)^2 \Arrow{by moving to left side} \\
+% f(x)^2 - g(x)^2 \ge 0
+% \end{WithArrows}$
+%
+% \interitem
+% In the following example, we use five columns all centered (the environment
+% |{DispWithArrows*}| is presented p.~\pageref{DispWithArrows}).
+%
+% \begin{Verbatim}
+% \begin{DispWithArrows*}[~emphase#format = ccccc@,
+% wrap-lines,
+% tikz = {align = flush left},
+% interline=1mm]
+% k & \;\le\; & t & \;\le\; & k+1 \\
+% \frac{1}{k+1} & \le & \frac{1}{t} & \le & \frac{1}{k}
+% \Arrow{we can integrate the inequalities since $k \leq k+1$ } \\
+% \int\limits_k^{k+1} \frac{d t}{k+1}
+% & \le & \int\limits_k^{k+1} \frac{dt}{t}
+% & \le & \int\limits_k^{k+1} \frac{dt}{k} \\
+% \frac{1}{k+1} & \le & \ln(k+1)-\ln(k) & \le & \frac{1}{k}
+% \end{DispWithArrows*}
+% \end{Verbatim}
+% \begin{DispWithArrows*}[format = ccccc,
+% wrap-lines,
+% tikz = {align = flush left},
+% interline=1mm]
+% k & \;\le\; & t & \;\le\; & k+1 \\
+% \frac{1}{k+1} & \le & \frac{1}{t} & \le & \frac{1}{k}
+% \Arrow{we can integrate the inequalities since $k \leq k+1$ } \\
+% \int\limits_k^{k+1} \frac{d t}{k+1}
+% & \le & \int\limits_k^{k+1} \frac{dt}{t}
+% & \le & \int\limits_k^{k+1} \frac{dt}{k} \\
+% \frac{1}{k+1} & \le & \ln(k+1)-\ln(k) & \le & \frac{1}{k}
+% \end{DispWithArrows*}
+%
+%
+% \section{Precise positioning of the arrows}
+%
+%
+% The environment |{WithArrows}| defines, during the composition of the array,
+% two series of nodes materialized in red in the following example.\footnote{The
+% option |show-nodes| can be used to materialize the nodes. The nodes are in
+% fact Tikz nodes of shape ``rectangle'', but with zero width. An arrow between
+% two nodes starts at the \emph{south} anchor of the first node and arrives at
+% the \emph{north} anchor of the second node.}
+%
+% \smallskip
+% $\begin{WithArrows}[displaystyle,show-nodes]
+% I
+% & = \int_{\frac{\pi}4}^0 \ln\Bigl(1+\tan\left(\tfrac{\pi}4-u\right)\Bigr)(-d u) \\
+% & = \int_0^{\frac{\pi}4} \ln\Bigl(1+\tan\left(\tfrac{\pi}4-u\right)\Bigr)d u \\
+% & = \int_0^{\frac{\pi}4}\ln\left(1+\frac{1-\tan u}{1+\tan u}\right)\, d u \\
+% & =\int_0^{\frac{\pi}4}\ln\left(\frac{1+\tan u+1-\tan u}{1+\tan u}\right) d u \\
+% & =\int_0^{\frac{\pi}4} \ln\left(\frac2{1+\tan u}\right)\, d u\\
+% & =\int_0^{\frac{\pi}4}\bigl(\ln2-\ln(1+\tan u)\bigr)\, d u \\
+% & =\frac{\pi}4\ln2-\int_0^{\frac{\pi}4}\ln(1+\tan u)\, d u \\
+% & =\frac{\pi}4\ln2-I
+% \end{WithArrows}$
+%
+% \bigskip
+% The nodes of the left are at the end of each line of text. These nodes will be
+% called \emph{left nodes}. The nodes of the right side are aligned vertically
+% on the right side of the array. These nodes will be called \emph{right nodes}.
+%
+% By default, the arrows use the right nodes. We will say that they are in |rr|
+% mode ($r$ for \emph{right}). These arrows are vertical (we will say that an
+% arrow is \emph{vertical} when its two ends have the same abscissa).
+%
+%
+% \smallskip
+% However, it's possible to use the left nodes, or a combination of left and
+% right nodes, with one of the options |lr|, |rl| and |ll| ($l$ for
+% \emph{left}). Those arrows are, usually, not vertical.
+%
+%
+% Therefore
+% $\begin{WithArrows}[displaystyle]
+% I
+% & = \int_{\frac{\pi}4}^0 \ln\Bigl(1+\tan\left(\tfrac{\pi}4-u\right)\Bigr)(-d u)
+% \Arrow[lr]{This arrow uses the |lr| option.}\\
+% & = \int_0^{\frac{\pi}4} \ln\Bigl(1+\tan\left(\tfrac{\pi}4-u\right)\Bigr)d u \\
+% & = \int_0^{\frac{\pi}4}\ln\left(1+\frac{1-\tan u}{1+\tan u}\right)\, d u \\
+% & =\int_0^{\frac{\pi}4}\ln\left(\frac{1+\tan u+1-\tan u}{1+\tan u}\right) d u
+% \Arrow[ll,jump=2,tikz={text width = 5cm}]{This arrow uses a |ll| option
+% and a |jump| equal to $2$}\\
+% & =\int_0^{\frac{\pi}4} \ln\left(\frac2{1+\tan u}\right)\, d u\\
+% & =\int_0^{\frac{\pi}4}\bigl(\ln2-\ln(1+\tan u)\bigr)\, d u \\
+% & =\frac{\pi}4\ln2-\int_0^{\frac{\pi}4}\ln(1+\tan u)\, d u \\
+% & =\frac{\pi}4\ln2-I
+% \end{WithArrows}$
+%
+%
+%
+% \interitem
+% There is also an option called |i| (\emph{i} for \emph{intermediate}). With
+% this option, the arrow is vertical and at the leftmost position.
+%
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% (a+b)(a+ib)(a-b)(a-ib)
+% & = (a+b)(a-b)\cdot(a+ib)(a-ib) \\
+% & = (a^2-b^2)(a^2+b^2) \Arrow~emphase#[i]@{because $(x-y)(x+y)=x^2-y^2$}\\
+% & = a^4-b^4
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% (a+b)(a+ib)(a-b)(a-ib)
+% & = (a+b)(a-b)\cdot(a+ib)(a-ib) \\
+% & = (a^2-b^2)(a^2+b^2) \Arrow[i]{because $(x-y)(x+y)=x^2-y^2$}\\
+% & = a^4-b^4
+% \end{WithArrows}$
+%
+%
+% \interitem
+% The environment |{WithArrows}| gives also a |group| option. With this option,
+% \emph{all} the arrows of the environment are grouped on a same vertical line
+% and at a leftmost position.
+% %
+% \begin{Verbatim}[formatcom=\small\color{gray}]
+% $\begin{WithArrows}[~emphase#displaystyle,group@]
+% 2xy'-3y=\sqrt x
+% & \Longleftrightarrow 2x(K'y_0+Ky_0')-3Ky_0 = \sqrt x \\
+% & \Longleftrightarrow 2xK'y_0 + K(2xy_0'-3y_0) = \sqrt x \\
+% & \Longleftrightarrow 2x K'y_0 = \sqrt x \Arrow{...}\\
+% ...
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+%
+% $\begin{WithArrows}[displaystyle,group]
+% 2xy'-3y=\sqrt x
+% & \Longleftrightarrow 2x(K'y_0+Ky_0')-3Ky_0 = \sqrt x \\
+% & \Longleftrightarrow 2xK'y_0 + K(2xy_0'-3y_0) = \sqrt x \\
+% & \Longleftrightarrow 2x K'y_0 = \sqrt x \Arrow{we replace $y_0$ by its value}\\
+% & \Longleftrightarrow 2xK'x^{\frac32} = x^{\frac12} \Arrow{simplification of the $x$}\\
+% & \Longleftrightarrow K' = \tfrac1{2x^2} \Arrow{antiderivation}\\
+% & \Longleftrightarrow K = -\tfrac1{2x}
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% The environment |{WithArrows}| gives also a |groups| option (with a \emph{s}
+% in the name). With this option, the arrows are divided into several
+% ``groups''. Each group is a set of connected\footnote{More precisely: for each
+% arrow $a$, we note $i(a)$ the number of its initial row and $f(a)$ the number
+% of its final row; for two arrows $a$ and $b$, we say that $a \sim b$ when
+% $\llbracket i(a),f(a)\rrbracket \cap \llbracket i(b),f(b)\rrbracket \neq
+% \varnothing$; the groups are the equivalence classes of the transitive closure
+% of $\sim$.} arrows. All the arrows of a given group are grouped on a same
+% vertical line and at a leftmost position.
+%
+% \bigskip
+% $\begin{WithArrows}[groups]
+% A & = B \Arrow{one} \\
+% & = C+D \Arrow{two} \\
+% & = D' \\
+% & = E+F+G+H+I \\
+% & = K + L + M \Arrow{three}\\
+% & = N \Arrow{four}\\
+% & = O
+% \end{WithArrows}$
+%
+% \bigskip
+% In an environment which uses the option |group| or the option |groups|, it's
+% still possible to give an option of position (|ll|, |lr|, |rl|, |rr| or |i|)
+% to an individual arrow. Such arrow will be drawn irrespective of the groups.
+% It's also possible to start a new group by applying the option |new-group| to
+% an given arrow.
+%
+% \bigskip
+% If desired, the option |group| or the option |groups| can be given to the
+% command |\WithArrowsOptions| so that it will become the default value. In this
+% case, it's still possible to come back to the default behaviour for a given
+% environment |{WithArrows}| with the option |rr|: |\begin{WithArrows}[rr]|
+%
+%
+% \vspace{1cm}
+% In the following example, we have used the option |group| for the environment
+% and the option |rr| for the last arrow (that's why the last arrow is not
+% aligned with the others).
+%
+% $\begin{WithArrows}[interline=1mm,group]
+% \sum\limits_{k=0}^n\frac{\cos kx}{\cos^k x}
+% & = \sum\limits_{k=0}^n \frac{\Re (e^{ikx})}{(\cos x)^k}
+% \Arrow{$(\cos x)^k$ is real} \\
+% & = \sum\limits_{k=0}^n \Re\left(\frac{e^{ikx}}{(\cos x)^k}\right)
+% \Arrow{$\Re(z+z')=\Re(z)+\Re(z')$}\\
+% & = \Re \left(\sum\limits_{k=0}^n \left(\frac{e^{ix}}{\cos x}\right)^k\right)
+% \Arrow{sum of terms of a geometric progression} \\
+% & = \Re \left(\frac{1-\left(\frac{e^{ix}}{\cos x}\right)^{n+1}}{1-\frac{e^{ix}}{\cos x}} \right)
+% \Arrow{algebraic calculation} \\
+% & = \Re \left(\frac{1-\frac{e^{i(n+1)x}}{\cos^{n+1}x}}{1-\frac{e^{ix}}{\cos x}}\right)
+% \Arrow{reduction to common denominator} \\
+% & = \Re \left(\frac{\frac{\cos^{n+1}x-e^{i(n+1)x}}{\cos^{n+1}x}}{\frac{\cos x-e^{ix}}{\cos x}}\right)
+% \Arrow{$\Re(kz) = k\cdot\Re(z)$ if $k$ is real} \\
+% & = \frac1{\cos^n x}\Re \left(\frac{\cos^{n+1}x-e^{i(n+1)x}}{\cos x-e^{ix}}\right)
+% \Arrow[rr]{algebraic form of the complexes} \\
+% & =\frac1{\cos^n x}\Re\left(\frac{\cos^{n+1}x-(\cos(n+1)x+i\sin(n+1)x)}{\cos x-(\cos x+i\sin x)}\right) \\
+% & =\frac1{\cos^n x}\Re\left(\frac{(\cos^{n+1}x-\cos(n+1)x)-i\sin(n+1)x}{-i\sin x}\right) \\
+% & = \frac1{\cos^nx}\cdot\frac{\sin(n+1)x}{\sin x}
+% \end{WithArrows}$
+%
+% \interitem
+%
+% \section[The options 'up' and 'down' for individual arrows]%
+% {The options ``up'' and ``down'' for individual arrows}
+%
+% \label{up-and-down}
+% At the local level, there are also two options for individuals arrows, called
+% ``|up|'' and ``|down|''. The following example illustrates these types of
+% arrows:
+%
+% \begin{Verbatim}
+% \(\begin{WithArrows}
+% A & = B
+% \Arrow~emphase#[up]@{an arrow of type \texttt{up}} \\
+% & = C + C + C + C + C + C + C + C \\
+% & = C + C + C + C + C + C + C + C
+% \Arrow~emphase#[down]@{an arrow of type \texttt{down}} \\
+% & = E + E
+% \end{WithArrows}\)
+% \end{Verbatim}
+%
+% \vspace{1cm}
+% \(\begin{WithArrows}
+% A & = B
+% \Arrow[up]{an arrow of type \texttt{up}} \\
+% & = C + C + C + C + C + C + C + C \\
+% & = C + C + C + C + C + C + C + C
+% \Arrow[down]{an arrow of type \texttt{down}} \\
+% & = E + E
+% \end{WithArrows}\)
+%
+%
+% \vspace{1cm}
+% The options |up| and |down| require the package \pkg{varwidth} and the Tikz
+% library \pkg{calc}. It they are not loaded, an error will be raised.
+%
+%
+% \interitem
+%
+% \section{Comparison with the environment \{aligned\}}
+%
+% |{WithArrows}| bears similarities with the environment |{aligned}| of the
+% extension \pkg{amsmath}. These are only similarities because |{WithArrows}|
+% has not been written upon the environment |{aligned}|.\footnote{In fact, it's
+% possible to use the package \pkg{witharrows} without the package
+% \pkg{amsmath}.}
+%
+% \interitem
+% As in the environments of \pkg{amsmath}, it's possible to change the spacing
+% between two given rows with the option of the command |\\| of end of line
+% (it's also possible to use |\\*| but it has exactly the same effect as |\\|
+% since an environment |{WithArrows}| is always unbreakable). This option is
+% designed to be used with positive values only.
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{we expand} ~emphase#\\[2ex]@
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \\*[2ex]
+% \noalign{\vspace{3mm}}
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+%
+% \interitem
+% In the environments of \pkg{amsmath} (or \pkg{mathtools}), the spacing between
+% rows is fixed by a parameter called |\jot| (it's a dimension and not a skip).
+% That's also the case for the environment |{WithArrows}|. An option |jot| has
+% been given to the environment |{WithArrows}| in order to change the value of
+% this parameter |\jot| for a given environment.\footnote{It's also possible to
+% change |\jot| with the environment |{spreadlines}| of \pkg{mathtools}.}
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}[displaystyle,~emphase#jot=2ex@]
+% F & = \frac12G \Arrow{we expand}\\
+% & = H + \frac12K \Arrow{we go on}\\
+% & = K
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+%
+% $\begin{WithArrows}[displaystyle,jot=2ex]
+% F & = \frac12G \Arrow{we expand}\\
+% & = H + \frac12K \Arrow{we go on}\\
+% & = K
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% However, this new value of |\jot| will also be used in other alignments
+% included in the environment~|{WithArrows}|:
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}[jot=2ex]
+% \varphi(x,y) = 0 & \Leftrightarrow (x+y)^2 + (x+2y)^2 = 0
+% \Arrow{$x$ and $y$ are real}\\
+% & \Leftrightarrow \left\{
+% \begin{aligned}
+% x+y & = 0 \\
+% x+2y & = 0
+% \end{aligned}
+% \right.
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+%
+% $\begin{WithArrows}[jot=2ex]
+% \varphi(x,y) = 0 & \Leftrightarrow (x+y)^2 + (x+2y)^2 = 0
+% \Arrow{$x$ and $y$ are real}\\
+% & \Leftrightarrow \left\{
+% \begin{aligned}
+% x+y & = 0 \\
+% x+2y & = 0
+% \end{aligned}
+% \right.
+% \end{WithArrows}$
+%
+% \bigskip
+% Maybe this doesn't correspond to the desired outcome. That's why an option
+% |interline| is proposed. It's possible to use a skip (=glue) for this option.
+% %
+% \begin{Verbatim}
+% $\begin{WithArrows}[~emphase#interline=2ex@]
+% \varphi(x,y) = 0 & \Leftrightarrow (x+y)^2 + (x+2y)^2 = 0
+% \Arrow{$x$ and $y$ are real}\\
+% & \Leftrightarrow \left\{
+% \begin{aligned}
+% x+y & = 0 \\
+% x+2y & = 0 \\
+% \end{aligned}
+% \right.
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+%
+% $\begin{WithArrows}[interline=2ex]
+% \varphi(x,y) = 0 & \Leftrightarrow (x+y)^2 + (x+2y)^2 = 0
+% \Arrow{$x$ and $y$ are real}\\
+% & \Leftrightarrow \left\{
+% \begin{aligned}
+% x+y & = 0 \\
+% x+2y & = 0 \\
+% \end{aligned}
+% \right.
+% \end{WithArrows}$
+%
+%
+% \interitem
+% Like the environment |{aligned}|, |{WithArrows}| has an option of placement
+% which can assume the values |t|, |c| or |b|. However, the default value is not
+% |c| but |t|. If desired, it's possible to have the |c| value as the default
+% with the command |\WithArrowsOptions{c}| at the beginning of the document.
+% %
+% \begin{Verbatim}
+% So\enskip
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% So\enskip
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+% \bigskip
+% The value |c| may be useful, for example, if we want to add curly braces:
+%
+% \smallskip
+% \begin{Verbatim}
+% Let's set\enskip $~emphase#\left\{@
+% \begin{WithArrows}[~emphase#c@]
+% f(x) & = 3x^3+2x^2-x+4
+% \Arrow[tikz=-]{both are polynoms}\\
+% g(x) & = 5x^2-5x+6
+% \end{WithArrows}
+% ~emphase#\right.@$
+% \end{Verbatim}
+%
+%
+% Let's set\enskip $\left\{
+% \begin{WithArrows}[c]
+% f(x) & = 3x^3+2x^2-x+4
+% \Arrow[tikz=-]{both are polynoms}\\
+% g(x) & = 5x^2-5x+6
+% \end{WithArrows}
+% \right.$
+%
+%
+% \interitem
+% Unlike |{aligned}|, the environment |{WithArrows}| uses |\textstyle| by
+% default.
+%
+% Once again, it's possible to change this behaviour with |\WithArrowsOptions|:
+%
+% \quad |\WithArrowsOptions{displaystyle}|.
+%
+%
+% \smallskip
+% The following example is composed with |{aligned}|:\par\nobreak
+%
+% \smallskip
+% $\left\{
+% \begin{aligned}
+% \sum_{i=1}^n (x_i+1)^2
+% & = \sum_{i=1}^n (x_i^2 + 2x_i+1) \\
+% & = \sum_{i=1}^n x_i^2 + 2 \sum_{i=1}^nx_i + n
+% \end{aligned}
+% \right.$
+%
+%
+% \medskip
+% The following is composed with |{WithArrows}[c,displaystyle]|. The results are
+% strictly identical.\footnote{In versions of \pkg{amsmath} older than the
+% 5~nov.~2016, a thin space was added on the left of an environment |{aligned}|.
+% The new versions do not add this space and neither do
+% |{WithArrows}|.}\par\nobreak
+%
+% \smallskip
+% $\left\{
+% \begin{WithArrows}[c,displaystyle]
+% \sum_{i=1}^n (x_i+1)^2
+% & = \sum_{i=1}^n (x_i^2 + 2x_i+1) \\
+% & = \sum_{i=1}^n x_i^2 + 2 \sum_{i=1}^nx_i + n
+% \end{WithArrows}
+% \right.$
+%
+%
+% \section{Arrows in nested environments}
+%
+% \label{NestedEnv}
+%
+% The environments |{WithArrows}| can be nested. In this case, the options given
+% to the encompassing environment applies also to the inner ones (with logical
+% exceptions for |interline|, |code-before| and |code-after|). The command |Arrow|
+% can be used as usual in each environment |{WithArrows}|.
+%
+% \begin{Verbatim}[formatcom=\small\color{gray}]
+% $~emphase#\begin{WithArrows}@
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \Arrow{the numbers are real}\\
+% & \Leftrightarrow
+% \left\{~emphase#\begin{WithArrows}@[c]
+% x+2y & = 0 \\
+% 2x+4y & = 0
+% ~emphase#\end{WithArrows}@\right. \\
+% & \Leftrightarrow
+% \left\{~emphase#\begin{WithArrows}@[c]
+% x+2y & = 0 \Arrow[tikz=-]{the same equation}\\
+% x+2y & = 0
+% ~emphase#\end{WithArrows}@\right. \\
+% & \Leftrightarrow x+2y=0
+% ~emphase#\end{WithArrows}@$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \Arrow{the numbers are real}\\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \\
+% 2x+4y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \Arrow[tikz=-]{the same equation}\\
+% x+2y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow x+2y=0
+% \end{WithArrows}$
+%
+% \bigskip
+% However, one may want to draw an arrow between rows that are not in the same
+% environment. For example, one may want to draw the following arrow :
+%
+% \bigskip
+% $\begin{WithArrows}[code-after = \Arrow[v]{1-2}{2-2}{division by $2$} ]
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \\
+% 2x+4y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \\
+% x+2y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow x+2y=0
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% Such a construction is possible by using |\Arrow| in the |code-after| option.
+% Indeed, in |code-after|, a special version of |\Arrow| is available (we will
+% call it ``|\Arrow| in |code-after|'').
+%
+% \smallskip
+% A command |\Arrow| in |code-after| takes three arguments :
+% \begin{itemize}
+% \item a specification of the start row of the arrow ;
+% \item a specification of the end row of the arrow ;
+% \item the label of the arrow.
+% \end{itemize}
+% As usual, it's also possible to give options within square brackets before or
+% after the three arguments. However, these options are limited (see below).
+%
+% \bigskip
+% The specification of the row is constructed with the position of the concerned
+% environment in the nesting tree, followed (after an hyphen) by the number of
+% the row.
+%
+% \bigskip
+% In the previous example, there are two environments |{WithArrows}| nested in
+% the main environment |{WithArrows}|.
+%
+% $\begin{WithArrows}[tikz-code = {\path (#1) to node {#3} (#2) ; }]
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \\
+% & \Leftrightarrow \color{blue}
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \Arrow{environment number 1}\\
+% 2x+4y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow \color{red}
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \Arrow{environment number 2}\\
+% x+2y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow x+2y=0
+% \end{WithArrows}$
+%
+% \bigskip
+% The arrow we want to draw starts in the row~$2$ of the sub-environment
+% number~$1$ (and therefore, the specification is |1-2|) and ends in the row~$2$
+% of the sub-environment number~$2$ (and therefore, the specification is |2-2|).
+% We can draw the arrow with the following command |\Arrow| in |code-after| :
+% \begin{Verbatim}
+% $\begin{WithArrows}[~emphase#code-after = \Arrow{1-2}{2-2}{division by $2$}@ ]
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \\
+% .........
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}[code-after = \Arrow{1-2}{2-2}{division by $2$} ]
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \\
+% 2x+4y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \\
+% x+2y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow x+2y=0
+% \end{WithArrows}$
+%
+% \bigskip
+% The options allowed for a command |\Arrow| in |code-after| are : |ll|, |lr|,
+% |rl|, |rr|, |v|, |xoffset|, |tikz| and |tikz-code|. Except |v|, which is
+% specific to |\Arrow| in |code-after|, all these options have their usual
+% meaning.
+%
+% With the option |v|, the arrow drawn is vertical to an abscissa computed with
+% the start row and the end row only : the intermediate lines are not taken into
+% account unlike with the option |i|. Currently, the option |i| is not available
+% for the command~|\Arrow| in |code-after|. However, it's always possible to
+% translate an arrow with |xoffset| (or |xshift| of Tikz).
+% \begin{Verbatim}
+% $\begin{WithArrows}[code-after=\Arrow~emphase#[v]@{1-2}{2-2}{division by $2$}]
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \\
+% .........
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}[code-after = \Arrow[v]{1-2}{2-2}{division by $2$} ]
+% \varphi(x,y)=0
+% & \Leftrightarrow (x+2y)^2+(2x+4y)^2 = 0 \\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \\
+% 2x+4y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow
+% \left\{\begin{WithArrows}[c]
+% x+2y & = 0 \\
+% x+2y & = 0
+% \end{WithArrows}\right. \\
+% & \Leftrightarrow x+2y=0
+% \end{WithArrows}$
+%
+%
+% \interitem
+% The package \pkg{witharrows} gives also another command available only in
+% |code-after|: the command |\MultiArrow|. This command draws a ``rak''. The list
+% of the rows of the environment concerned by this rak are given in the first
+% argument of the command |\MultiArrow|. This list is given with the syntax of
+% the list in a |\foreach| command of \pkg{pgffor}.
+%
+%
+% \begin{Verbatim}
+% $\begin{WithArrows}[tikz = rounded corners,
+% code-after = {~emphase#\MultiArrow{1,...,4}{text}@} ]
+% A & = B \\
+% & = C \\
+% & = D \\
+% & = E \\
+% & = F
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+%
+% $\begin{WithArrows}[tikz = rounded corners,
+% code-after = {\MultiArrow{1,...,4}{text}}]
+% A & = B \\
+% & = C \\
+% & = D \\
+% & = E \\
+% & = F
+% \end{WithArrows}$
+%
+% \medskip
+% As of now, there is no option available for the command |\MultiArrow| (maybe
+% in a future release).
+%
+%
+% \bigskip
+% \section{Arrows from outside environments \{WithArrows\}}
+%
+% If someone wants to draw arrows from outside the environments |{WithArrows}|,
+% he can use the Tikz nodes created in the environments.
+%
+% The Tikz name of a node created by \pkg{witharrows} is prefixed by |wa-|.
+% Then, we have a list of numbers which give the position in the nesting tree
+% and the row number in the environment. At the end, we have the suffixe |l| for
+% a ``left node'' and |r| for a ``right node''.
+%
+% \smallskip
+% For illustrative purposes, we give an example of nested environments
+% |{WithArrows}|, and, for each ``right node'', the name of that
+% node.\footnote{There is an option |show-node-names| to show the names of these
+% nodes.}
+%
+% \medskip
+% \[\begin{WithArrows}[show-nodes,show-node-names]
+% A & \vartriangleleft B+B+B+B+B+B+B+B+B+B+B+B+B \\
+% & \vartriangleleft \left\{
+% \begin{WithArrows}[c]
+% C & \vartriangleleft D \\
+% E & \vartriangleleft F
+% \end{WithArrows}
+% \right. \\
+% & \vartriangleleft
+% \left\{
+% \begin{WithArrows}[c]
+% G & \vartriangleleft H+H+H+H+H+H+H \\
+% I & \vartriangleleft
+% \left\{
+% \begin{WithArrows}
+% J &\vartriangleleft K \\
+% L &\vartriangleleft M
+% \end{WithArrows}
+% \right.
+% \end{WithArrows}
+% \right. \\
+% & \vartriangleleft
+% \left\{
+% \begin{WithArrows}[c]
+% N & \vartriangleleft O \\
+% P & \vartriangleleft Q
+% \end{WithArrows}
+% \right.
+% \end{WithArrows}\]
+%
+% \medskip
+% The package \pkg{witharrows} provides some tools facilitating the use of these
+% nodes:
+% \begin{itemize}
+% \item the command |\WithArrowsLastEnv| gives the number of the last
+% environment of level~$0$ (\emph{i.e.} which is not included in another
+% environnment of the package \pkg{witharrows});
+%
+% \item a name can be given to a given environment with the option |name| and,
+% in this case, the nodes created in the environment will have aliases
+% constructed with this name;
+%
+% \item the Tikz style |WithArrows/arrow| is the style used by \pkg{witharrows}
+% when drawing an arrow\footnote{More precisely, this style is given to the Tikz
+% option ``|every path|'' before drawing the arrow with the code of the option
+% |tikz-code|. This style is modified (in TeX scopes) by the option |tikz| of
+% \pkg{witharrows}.};
+%
+% \item the Tikz style |WithArrows/arrow/tips| is the style for the tip of the
+% arrow (loaded by |WithArrows/arrow|).
+% \end{itemize}
+%
+% For example, we can draw an arrow from \texttt{wa-\WithArrowsLastEnv-2-1-2-r.south}
+% to \texttt{wa-\WithArrowsLastEnv-3-2-r.north} with the following Tikz command.
+%
+% \begin{Verbatim}
+% \begin{tikzpicture}[remember picture,overlay]
+% \draw [WithArrows/arrow]
+% ([xshift=3mm]wa-\WithArrowsLastEnv-2-1-2-r.south)
+% to ([xshift=3mm]wa-\WithArrowsLastEnv-3-2-r.north) ;
+% \end{tikzpicture}
+% \end{Verbatim}
+%
+% \[\begin{WithArrows}
+% A & \vartriangleleft B+B+B+B+B+B+B+B+B+B+B+B+B \\
+% & \vartriangleleft \left\{
+% \begin{WithArrows}[c]
+% C & \vartriangleleft D \\
+% E & \vartriangleleft F
+% \end{WithArrows}
+% \right. \\
+% & \vartriangleleft
+% \left\{
+% \begin{WithArrows}[c]
+% G & \vartriangleleft H+H+H+H+H+H+H \\
+% I & \vartriangleleft
+% \left\{
+% \begin{WithArrows}
+% J &\vartriangleleft K \\
+% L &\vartriangleleft M
+% \end{WithArrows}
+% \right.
+% \end{WithArrows}
+% \right. \\
+% & \vartriangleleft
+% \left\{
+% \begin{WithArrows}[c]
+% N & \vartriangleleft O \\
+% P & \vartriangleleft Q
+% \end{WithArrows}
+% \right.
+% \end{WithArrows}\]
+%
+% \begin{tikzpicture}[remember picture,overlay]
+% \draw [WithArrows/arrow]
+% ([xshift=3mm]wa-\WithArrowsLastEnv-2-1-2-r.south)
+% to ([xshift=3mm]wa-\WithArrowsLastEnv-3-2-r.north) ;
+% \end{tikzpicture}
+%
+% \medskip
+% In this case, it would be easier to use a command |\Arrow| in |code-after| but
+% this is an example to explain how the Tikz nodes created by \pkg{witharrows}
+% can be used.
+%
+% \bigskip
+% In the following example, we create two environments |{WithArrows}| named
+% ``|first|'' and ``|second|'' and we draw a line between a node of the first
+% and a node of the second.
+%
+% \begin{Verbatim}
+% $\begin{WithArrows}[~emphase#name=first@]
+% A & = B \\
+% & = C
+% \end{WithArrows}$
+%
+% \bigskip
+% $\begin{WithArrows}[~emphase#name=second@]
+% A' & = B' \\
+% & = C'
+% \end{WithArrows}$
+%
+% \begin{tikzpicture}[remember picture,overlay]
+% \draw [WithArrows/arrow]
+% ([xshift=3mm]~emphase#first@-1-r.south)
+% to ([xshift=3mm]~emphase#second@-1-r.north) ;
+% \end{tikzpicture}
+% \end{Verbatim}
+%
+%
+% \begin{center}
+% $\begin{WithArrows}[name=first]
+% A & = B \\
+% & = C
+% \end{WithArrows}$
+%
+% \bigskip
+% $\begin{WithArrows}[name=second]
+% A' & = B' \\
+% & = C'
+% \end{WithArrows}$
+% \end{center}
+%
+% \begin{tikzpicture}[remember picture,overlay]
+% \draw [WithArrows/arrow]
+% ([xshift=3mm]first-1-r.south)
+% to ([xshift=3mm]second-1-r.north) ;
+% \end{tikzpicture}
+%
+% \section{The environment \{DispWithArrows\}}
+% \label{DispWithArrows}
+%
+% As previously said, the environment |{WithArrows}| bears similarities with the
+% environment |{aligned}| of \pkg{amsmath} (and |mathtools|). This extension also
+% provides an environment |{DispWithArrows}| which is similar to the
+% environments |{align}| and |{flalign}| of \pkg{amsmath}.
+%
+% \medskip
+% The environment |{DispWithArrows}| must be used \emph{outside} math mode. Like
+% |{align}|, it should be used in horizontal mode.
+% \begin{Verbatim}
+% \begin{~emphase#DispWithArrows@}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{~emphase#DispWithArrows@}
+% \end{Verbatim}
+% \begin{DispWithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{DispWithArrows}
+%
+% \medskip
+% It's possible to use the command |\notag| (or |\nonumber|) to suppress a tag.
+%
+% It's possible to use the command |\tag| to put a special tag (e.g. $\star$).
+%
+% It's also possible to put a label to the line of an equation with the command
+% |\label|.
+%
+% These commands must be in the second column of the environment.
+% \begin{Verbatim}
+% \begin{DispWithArrows}
+% A & = (a+1)^2 \Arrow{we expand} ~emphase#\notag@ \\
+% & = a^2 + 2a + 1 ~emphase#\tag{$\star$} \label{my-equation}@
+% \end{DispWithArrows}
+% \end{Verbatim}
+% \begin{DispWithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \notag \\
+% & = a^2 + 2a + 1 \tag{$\star$} \label{my-equation}
+% \end{DispWithArrows}
+% A link to the equation \eqref{my-equation}. This link has been composed with
+% |\eqref{my-equation}| (the command |\eqref| is a command of \pkg{amsmath}).
+%
+% \medskip
+% If \pkg{amsmath} (or \pkg{mathtools}) is loaded, it's also possible to use
+% |\tag*| which, as in \pkg{amsmath}, typesets the tag without the parenthesis.
+% For example, it's possible to use it to put the symbol |\square| of
+% \pkg{amssymb}. This symbol is often used to mark the end of a
+% proof.\footnote{Notice that the environment |{DispWithArrows}| is compatible
+% with the command |\qedhere| of \pkg{amsthm}.}
+% \begin{Verbatim}
+% \begin{DispWithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \notag \\
+% & = a^2 + 2a + 1 ~emphase#\tag*{$\square$}@
+% \end{DispWithArrows}
+% \end{Verbatim}
+% \begin{DispWithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \notag \\
+% & = a^2 + 2a + 1 \tag*{$\square$}
+% \end{DispWithArrows}
+%
+% \medskip
+% It's also possible to suppress all the autogenerated numbers with the boolean
+% option |notag| (or |nonumber|), at the global or environment level. There is
+% also an environment |{DispWithArrows*}| which suppresses all these
+% numbers.\footnote{Even in this case, it's possible to put a ``manual tag''
+% with the command |\tag|.}
+% \begin{Verbatim}
+% \begin{~emphase#DispWithArrows*@}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{~emphase#DispWithArrows*@}
+% \end{Verbatim}
+% \begin{DispWithArrows*}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{DispWithArrows*}
+%
+% \medskip
+% In fact, there is also another option |tagged-lines| which can be used to
+% control the lines that will be tagged. The value of this option is a list of
+% the numbers of the lines that must to be tagged. For example, with the option
+% |tagged-lines = {first,3,last}|, only the first, the third and the last line
+% of the environment will be tagged. There is also the special value |all| which
+% means that all the lines will be tagged.
+% \begin{Verbatim}
+% \begin{DispWithArrows}[~emphase#tagged-lines = last@]
+% A & = A_1 \Arrow{first stage} \\
+% & = A_2 \Arrow{second stage} \\
+% & = A_3
+% \end{DispWithArrows}
+% \end{Verbatim}
+% \begin{DispWithArrows}[tagged-lines = last]
+% A & = A_1 \Arrow{first stage} \\
+% & = A_2 \Arrow{second stage} \\
+% & = A_3
+% \end{DispWithArrows}
+%
+% \bigskip
+% With the option |fleqn|, the environment is composed flush left (in a way
+% similar to the option |fleqn| of the standard classes of LaTeX). In this case,
+% the left margin can be controlled with the option |mathindent| (with a name
+% inspired by the parameter |\mathindent| of standard LaTeX). The default value
+% of this parameter is 25~pt.
+%
+% \begin{Verbatim}
+% \begin{DispWithArrows}[~emphase#fleqn,mathindent = 1cm@]
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{DispWithArrows}
+% \end{Verbatim}
+% \begin{DispWithArrows}[fleqn,mathindent = 1cm]
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{DispWithArrows}
+%
+% \medskip
+% \emph{Remark} : By design, the option |fleqn| of \pkg{witharrows} is
+% independent of the option |fleqn| of LaTeX. Indeed, since the environments of
+% \pkg{witharrows} are meant to be used with arrows on the right side, the user
+% may want to use \pkg{witharrows} with the option |fleqn| (in order to have
+% more space on the right of the equations for the arrows) while still centering
+% the classical equations.
+%
+% \medskip
+% If the option |leqno| is used as a class option, the labels will be composed
+% on the left also for the environments |{DispWithArrows}| and
+% |{DispWithArrows*}|.\footnote{The package \pkg{amsmath} has an option |leqno|
+% but \pkg{witharrows}, of course, is not aware of that option: \pkg{witharrows}
+% only checks the option |leqno| of the document class.}
+%
+% \medskip
+% If the package \pkg{amsmath} is loaded, it's possible to use the command
+% |\intertext| in the environments |{DispWithArrows}|. It's also possible to use
+% the environment |{subequations}|. However, there is, for the environments
+% |{DispWithArrows}| an option |subequations| to encapsulate the environment in
+% an environment |{subequations}|.
+%
+% \medskip
+% In the following example, the key |{subequations}| is fixed by the command
+% |\WithArrowsOptions|. Each environment |{DispWithArrows}| will subnumerated
+% (in the scope of the |\WithArrowsOptions|)
+% \begin{Verbatim}
+% ~emphase#\WithArrowsOptions{subequations}@
+% First environment.
+% \begin{DispWithArrows}
+% A & = B \\
+% & = C
+% \end{DispWithArrows}
+% Second environment.
+% \begin{DispWithArrows}
+% D & = E \\
+% & = F
+% \end{DispWithArrows}
+% \end{Verbatim}
+% %
+% \begin{scope}
+% \WithArrowsOptions{subequations}
+% First environment.
+% \begin{DispWithArrows}
+% A & = B \\
+% & = C
+% \end{DispWithArrows}
+% Second environment.
+% \begin{DispWithArrows}
+% D & = E \\
+% & = F
+% \end{DispWithArrows}
+% \end{scope}
+%
+% \bigskip
+% If there is not enough space to put the tag at the end of a line, there is no
+% automatic positioning of the label on the next line (as in the environments of
+% \pkg{amsmath}). However, in |{DispWithArrows}|, the user can use the command
+% |\tagnextline| to manually require the composition of the tag on the following
+% line.
+% \begin{Verbatim}
+% \begin{DispWithArrows}[displaystyle]
+% S_{2(p+1)}
+% & =\sum_{k=1}^{2(p+1)} (-1)^k k^2 \\
+% & \smash[b]{=\sum_{k=1}^{2p}(-1)^kk²
+% +(-1)^{2p+1}(2p+1)^2+(-1)^{2p+2}(2p+2)^2} ~emphase#\tagnextline@ \\
+% &= S_{2p}-(2p+1)^2+(2p+2)^2\\
+% &=p(2p+1)-(2p+1)^2+(2p+2)^2\\
+% &= 2p^2+5p+3
+% \end{DispWithArrows}
+% \end{Verbatim}
+% \begin{center}
+% \color{gray}\vrule%
+% \begin{minipage}{275pt}\color{black}
+% \begin{DispWithArrows}[displaystyle]
+% S_{2(p+1)}
+% & =\sum_{k=1}^{2(p+1)} (-1)^k k^2 \\
+% & \smash[b]{=\sum_{k=1}^{2p}(-1)^kk^2+(-1)^{2p+1}(2p+1)^2+(-1)^{2p+2}(2p+2)^2}
+% \tagnextline \\
+% &= S_{2p}-(2p+1)^2+(2p+2)^2\\
+% &= 2p^2+p-4p^2-4p-1+4p^2+8p+4\\
+% &= 2p^2+5p+3
+% \end{DispWithArrows}
+% \end{minipage}%
+% \color{gray}\vrule
+% \end{center}
+%
+%
+%
+% \bigskip
+% The environments |{DispWithArrows}| and |{DispWithArrows*}| provide an option
+% |wrap-lines|. With this option, the lines of the label are automatically
+% wrapped on the right.\footnote{It's possible to avoid the hyphenations of the
+% words with the option ``|align = flush left|'' of Tikz.}\label{wrap-lines}
+%
+% \begin{Verbatim}
+% \begin{DispWithArrows*}[displaystyle,~emphase#wrap-lines@]
+% S_n
+% & = \frac1n \Re \left(\sum_{k=0}^{n-1}\bigl(e^{i\frac{\pi}{2n}}\bigr)^k\right)
+% \Arrow{sum of terms of a geometric progression of ratio $e^{i\frac{2\pi}n}$}\\
+% & = \frac1n \Re \left( \frac{1-\bigl(e^{i\frac{\pi}{2n}}\bigr)^n}
+% {1-e^{i\frac{\pi}{2n}}}\right)
+% \Arrow{This line has been wrapped automatically.} \\
+% & = \frac1n \Re \left(\frac{1-i}{1-e^{i\frac{\pi}{2n}}}\right)
+% \end{DispWithArrows*}
+% \end{Verbatim}
+% \begin{DispWithArrows*}[displaystyle,wrap-lines]
+% S_n
+% & = \frac1n \Re \left(\sum_{k=0}^{n-1}\bigl(e^{i\frac{\pi}{2n}}\bigr)^k\right)
+% \Arrow{sum of terms of a geometric progression of ratio $e^{i\frac{2\pi}n}$}\\
+% & = \frac1n \Re \left(
+% \frac{1-\bigl(e^{i\frac{\pi}{2n}}\bigr)^n}{1-e^{i\frac{\pi}{2n}}} \right)
+% \Arrow{This line has been wrapped automatically.} \\
+% & = \frac1n \Re \left(\frac{1-i}{1-e^{i\frac{\pi}{2n}}}\right)
+% \end{DispWithArrows*}
+%
+% \bigskip
+% The option |wrap-lines| doesn't apply to the environments |{WithArrows}|
+% nested in an environment |{DispWithArrows}| or |{DispWithArrows*}|. However,
+% it applies to the instructions |\Arrow| and |\MultiArrow| of the |code-after|
+% of the environments |{DispWithArrows}| or |{DispWithArrows*}|.
+%
+% \vspace{1cm}
+% We have said that the environments |{DispWithArrows}| and |{DispWithArrows*}|
+% should be used in horizontal mode and not in vertical mode. However, there is
+% an exception. These environments can be used directly after a |\item| of a
+% LaTeX list. In this case, no vertical space is added before the
+% environment.\footnote{It's possible to disable this feature with the option |standard-behaviour-with-items|.}
+%
+% \medskip
+% Here is an example. The use of |{DispWithArrows}| gives the ability to tag an
+% equation (and also to use |wrap-lines|).
+%
+% \begin{Verbatim}
+% ~emphase#\begin{enumerate}@
+% ~emphase#\item @
+% \begin{DispWithArrows}%
+% [displaystyle, wrap-lines, tagged-lines = last, fleqn, mathindent = 0 pt]
+% S_n
+% & = \frac1n \Re \left(\sum_{k=0}^{n-1}\bigl(e^{i\frac{\pi}{2n}}\bigr)^k\right)
+% \Arrow{we use the formula for a sum of terms of a geometric progression of
+% ratio $e^{i\frac{2\pi}n}$}\\
+% & = \frac1n \Re \left( \frac{1-\bigl(e^{i\frac{\pi}{2n}}\bigr)^n}
+% {1-e^{i\frac{\pi}{2n}}}\right)
+% \Arrow{$\bigl(e^{i\frac{\pi}{2n}}\bigr)^n = e^{i\frac{\pi}2}=i$} \\
+% & = \frac1n \Re \left(\frac{1-i}{1-e^{i\frac{\pi}{2n}}}\right)
+% \end{DispWithArrows}
+% ~emphase#\end{enumerate}@
+% \end{Verbatim}
+% \begin{enumerate}
+% \item
+% \begin{DispWithArrows}[displaystyle, wrap-lines, tagged-lines = last, fleqn, mathindent = 0 pt]
+% S_n
+% & = \frac1n \Re \left(\sum_{k=0}^{n-1}\bigl(e^{i\frac{\pi}{2n}}\bigr)^k\right)
+% \Arrow{we use the formula for a sum of terms of a geometric progression of
+% ratio $e^{i\frac{2\pi}n}$}\\
+% & = \frac1n \Re \left(
+% \frac{1-\bigl(e^{i\frac{\pi}{2n}}\bigr)^n}{1-e^{i\frac{\pi}{2n}}} \right)
+% \Arrow{$\bigl(e^{i\frac{\pi}{2n}}\bigr)^n = e^{i\frac{\pi}2}=i$} \\
+% & = \frac1n \Re \left(\frac{1-i}{1-e^{i\frac{\pi}{2n}}}\right)
+% \end{DispWithArrows}
+% \end{enumerate}
+%
+% \vspace{1cm}
+% The environment |{DispWithArrows}| is similar to the environment |{align}| of
+% \pkg{amsmath}. However, |{DispWithArrows}| is not constructed upon |{align}|
+% (in fact, it's possible to use \pkg{witharrows} without \pkg{amsmath}).
+%
+% There are differences between |{DispWithArrows}| and |{align}|.
+% \begin{itemize}
+% \item The environment |{DispWithArrows}| cannot be inserted in an environment
+% |{gather}| of \pkg{amsmath}.
+% \item An environment |{DispWithArrows}| is always unbreakable (even with
+% |\allowdisplaybreaks| of \pkg{amsmath}).
+% \item The commands |\label|, |\tag|, |\notag| and |\nonumber| are allowed only
+% in the last column.
+% \item After an |\item| of a LaTeX list, no vertical space is added (this can
+% be changed with the option |standard-behaviour-with-items|).
+% \item
+% \begin{bfseries}
+% Last but not least, by default, the elements of a |\{DispWithArrows\}|
+% are composed in |textstyle| and not in |displaystyle| (it's possible to change
+% this point with the option |displaystyle|).
+% \end{bfseries}
+% \end{itemize}
+%
+% \bigskip
+% Concerning the references, the package \pkg{witharrows} is compatible with the
+% extensions \pkg{autonum}, \pkg{cleveref}, \pkg{fancyref}, \pkg{fncylab},
+% \pkg{hyperref}, \pkg{listlbls}, \pkg{prettyref}, \pkg{refcheck},
+% \pkg{refstyle}, \pkg{showlabels}, \pkg{smartref}, \pkg{typedref} and
+% \pkg{varioref}, and with the options |showonlyrefs| and |showmanualtags| of
+% \pkg{mathtools}.\footnote{We recall that \pkg{varioref}, \pkg{hyperref},
+% \pkg{cleveref} and \pkg{autonum} must be loaded in this order. The package
+% \pkg{witharrows} can be loaded anywhere.}
+%
+% It is not compatible with \pkg{showkeys} (not all the labels are shown).
+%
+%
+%
+%
+% \subsection{The option <...> of DispWithArrows}
+%
+% The environment |{DispWithArrows}| provides an option |left-brace|. When present,
+% the value of this option is composed on the left, followed by a curly brace
+% (hence the name) and the body of the environment.\footnote{The option
+% |left-brace| can also be used without value: in this case, only the brace is drawn...}
+%
+% For lisibility, this option |left-brace| is also available with a special
+% syntax: it's possible to give this option between angle brackets
+% (\verb|<| and \verb|>|) just after \verb|{DispWithArrows}| (before the optional
+% arguments between square brackets).
+%
+% \bigskip
+% The following code is an example of multi-case equations.\footnote{The
+% environment |{cases}| of \pkg{amsmath} is a way to compose such multi-cases
+% equations. However, it's not possible to use the automatic numbering of
+% equations with this environment. The environment |{numcases}| of the extension
+% \pkg{cases} (written by Donald Arseneau) provides this possibility but, of
+% course, it's not possible to draw arrows with this extension.}
+%
+% \medskip
+%
+% \begin{BVerbatim}
+% \begin{DispWithArrows}~emphase#< \binom{n}{p} = >@[format = ll,fleqn,displaystyle]
+% 0 & \quad \text{if } p > n
+% \Arrow{if fact, it's a special case\\ of the following one} \\
+% \frac{n(n-1)\cdots(n-p+1)}{p!} & \quad \text{if } 0 \leq p \leq n \\
+% 0 & \quad \text{if } p < 0
+% \end{DispWithArrows}
+% \end{BVerbatim}
+% %
+% \begin{DispWithArrows}< \binom{n}{p} = >[format = ll,fleqn,displaystyle]
+% 0 & \quad \text{if } p > n
+% \Arrow{if fact, it's a special case\\ of the following one} \\
+% \frac{n(n-1)\cdots(n-p+1)}{p!} & \quad \text{if } 0 \leq p \leq n \\
+% 0 & \quad \text{if } p < 0
+% \end{DispWithArrows}
+%
+% \interitem
+% In the following example, we subnumerate the equations with the option
+% |subnumerate| (available when the package \pkg{amsmath} is loaded).
+%
+% \begin{Verbatim}
+% \begin{DispWithArrows}~emphase#< \label{system} (\ref*{system}) \Leftrightarrow >@[
+% format = l, subequations ]
+% x+y+z = -3 \Arrow[tikz=-,jump=2]{3 equations} \\
+% xy+xz+yz=-2 \\
+% xyz = -15 \label{last-equation}
+% \end{DispWithArrows}
+% \end{Verbatim}
+% %
+% \begin{DispWithArrows}< \label{system} (\ref*{system}) \Leftrightarrow >[
+% format = l, subequations]
+% x+y+z = -3 \Arrow[tikz=-,jump=2]{3 equations} \\
+% xy+xz+yz=-2 \\
+% xyz = -15 \label{last-equation}
+% \end{DispWithArrows}
+%
+%
+% \bigskip
+% The whole system is the equation \eqref{system} (this reference has been coded
+% by |\eqref{system}|) whereas the last equation is the equation
+% \eqref{last-equation} (this reference has been coded by
+% |\eqref{last-equation}|). The command |\ref*| used in the code above is
+% provided by \pkg{hyperref}. It's a variant of |\ref| which doesn't create
+% interactive link.
+%
+% \bigskip
+% With the option \verb|replace-left-brace-by|, it's possible to replace the
+% left curly brace by another extensible delimiter. For example,
+% ``|replace-left-brace-by = [\enskip|'' will compose with a bracket and add also a
+% |\enskip| after this bracket.
+%
+% \bigskip
+% \section{Advanced features}
+%
+% \subsection{Utilisation with plain-TeX}
+% \label{plain-TeX}
+%
+% The extension \pkg{witharrows} can be used with plain-TeX. In this case, the
+% extension must be loaded with |\input|:
+% \begin{Verbatim}
+% \input{witharrows.tex}
+% \end{Verbatim}
+%
+% \medskip
+% In plain-TeX, there is not environments as in LaTeX. Instead of using the
+% environment |{Witharrows}|, with |\begin{WithArrows}| and |\end{WithArrows}|,
+% one should use a pseudo-environnement delimited by |\WithArrows| and
+% |\endWithArrows| (idem for |{DispWithArrows}|).
+%
+% \begin{Verbatim}
+% $\WithArrows
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \endWithArrows$
+% \end{Verbatim}
+%
+% \medskip
+% The version of \pkg{witharrows} for plain-TeX doesn't provide all the
+% functionnlities of the LaTeX version. In particular, the funcionnalities which
+% deal with the number of the equations are not available (since they rely upon
+% the system of tags of LaTeX).
+%
+% \subsection{The option tikz-code : how to change the shape of the arrows}
+%
+% \label{tikz-code}
+%
+% The option |tikz-code|\footnote{For historical reasons, the option |tikz-code|
+% has an alias: |TikzCode|.} allows the user to change the shape of the
+% arrows.\footnote{If the option |wrap-lines| is used in an environment
+% |{DispWithArrows}| or |{DispWithArrows*}|, the option |tikz-code| will have no
+% effect for the arrows of this environment but only for the arrows in the
+% nested environments |{WithArrows}|.}
+%
+% \smallskip
+% For example, the options ``|up|'' and ``|down|'' described previously (cf.
+% p.~\pageref{up-and-down}) are programmed internally with |tikz-code|.
+%
+% \smallskip
+% The value of this option must be a valid Tikz drawing instruction (with the
+% final semicolon) with three markers |#1|, |#2| and |#3| for the start point,
+% the end point and the label of the arrow.
+%
+% \bigskip
+% By default, the value is the following:
+%
+% \smallskip
+% \qquad \verb|\draw (#1) to node {#3} (#2) ;|
+%
+%
+% \bigskip
+% In the following example, we replace this default path by a path with three
+% segments (and the node overwriting the second segment).
+% \begin{Verbatim}
+% \begin{WithArrows}[format=c,ygap=5pt,interline=4mm,
+% ~emphase#tikz-code = {\draw[rounded corners]@
+% ~emphase# (~#1) -- ([xshift=5mm]~#1)@
+% ~emphase# -- node[circle,@
+% ~emphase# draw,@
+% ~emphase# auto = false,@
+% ~emphase# fill = gray!50,@
+% ~emphase# inner sep = 1pt] {\tiny ~#3}@
+% ~emphase# ([xshift=5mm]~#2)@
+% ~emphase# -- (~#2) ; }@]
+% 3 (2x+4) = 6 \Arrow{$\div 3$} \\
+% 2x+4 = 2 \Arrow{$-4$} \\
+% 2x = -2 \Arrow{$\div 2$} \\
+% x = -1
+% \end{WithArrows}
+% \end{Verbatim}
+%
+%
+% \[\begin{WithArrows}[format=c,
+% ygap=5pt,
+% interline=4mm,
+% tikz-code = {\draw[rounded corners]
+% (#1)
+% --
+% ([xshift=5mm]#1)
+% -- node[circle,
+% draw,
+% auto=false,
+% fill=gray!50,
+% inner sep = 1pt] {\tiny #3}
+% ([xshift=5mm]#2)
+% --
+% (#2) ; }]
+% 3 (2x+4) = 6 \Arrow{$\div 3$} \\
+% 2x+4 = 2 \Arrow{$-4$} \\
+% 2x = -2 \Arrow{$\div 2$} \\
+% x = -1
+% \end{WithArrows}\]
+%
+% \bigskip
+% The environments |{DispWithArrows}| and its starred version
+% |{DispWithArrows*}| provide a command |\WithArrowsRightX| which can be used in
+% a definition of |tikz-code|. This command gives the $x$-value of the right side
+% of the composition box (taking into account the eventual tags of the
+% equations). For an example of use, see p.~\pageref{example-WithArrowsRightX}.
+%
+%
+% \bigskip
+% \subsection{The command \textbackslash WithArrowsNewStyle}
+%
+% The extension \pkg{witharrows} provides a command |\WithArrowsNewStyle| to
+% define styles in a way similar to the ``styles'' of Tikz.
+%
+% The command |\WithArrowsNewStyle| takes two mandatory arguments. The first is
+% the name of the style and the second is a list of key-value pairs. The scope
+% of the definition done by |\WithArrowsNewStyle| is the current TeX scope.
+%
+% The style can be used as a key at the document level (with
+% |\WithArrowsOptions|) or at the environment level (in the optional arguments
+% of |{WithArrows}| and |{DispWithArrows}|). The style can also be used in
+% another command |\WithArrowsNewStyle|.
+%
+% For an example of use, see p.~\pageref{example-WithArrowsRightX}.
+%
+%
+% \bigskip
+% \subsection{Vertical positioning of the arrows}
+%
+% There are four parameters for fine tuning of the vertical positioning of the
+% arrows : |ygap|, |ystart|, |start-adjust| and |end-adjust|.
+%
+% \medskip
+% We first explain the behaviour when the parameters |start-adjust| and
+% |end-adjust| are equal to zero:
+% \begin{itemize}
+% \item the option |ystart| sets the vertical distance between the base line of
+% the text and the start of the arrow (default value: 0.4 ex);
+% \item the option |ygap| sets the vertical distance between two consecutive
+% arrows (default value: 0.4~ex).
+% \end{itemize}
+%
+%
+% \bigskip
+% $\begin{WithArrows}[interline=1mm, adjust = 0pt]
+% (\cos x + \sin x)^2 & = \cos^2 x +2 \cos x \sin x + \sin^2 x\Arrow{}\tikz[remember picture] \coordinate (A) ; \\
+% & = \cos^2x + \sin^2x + 2\sin x\cos x \Arrow{} \\
+% & = 1 + \sin(2x)
+% \end{WithArrows}$
+%
+% \begin{tikzpicture}[remember picture,overlay,blue]
+% \draw (wa-\WithArrowsLastEnv-1-r.south) to ++(1,0) coordinate (B) to ++(0.1,0) ;;
+% \draw (A) to ++(1,0) coordinate (C) to ++(0.1,0) ;;
+% \draw (B) -- (C) ;
+% \draw[<-] (B) to ++(0,0.2) ;
+% \draw[<-] (C) to ++(0,-0.2) ;
+% \path (C) node[right=1mm] {|ystart|} ;
+% \draw (wa-\WithArrowsLastEnv-2-r.north) to ++(3,0) coordinate (E) to ++(0.1,0);
+% \draw (wa-\WithArrowsLastEnv-2-r.south) to ++(3,0) coordinate (F) to ++(0.1,0);
+% \draw (E) -- (F) ;
+% \draw[<-] (E) to ++(0,0.2) ;
+% \draw[<-] (F) to ++(0,-0.2) ;
+% \path (F) node[right=1mm] {|ygap|} ;
+% \end{tikzpicture}
+%
+% \interitem
+% However, for aesthetic reasons, when it's possible, \pkg{witharrows} starts
+% the arrow a bit higher (by an amount |start-adjust|) and ends the arrow a bit
+% lower (by an amount |end-adjust|). By default, both parameters |start-adjust|
+% and |end-adjust| are equal to $0.4$~ex.
+%
+% \bigskip
+% Here is for example the behaviour without the mechanism of |start-adjust| and
+% |end-adjust| (this was the standard behaviour for versions prior to 1.13).
+% % \begin{Verbatim}
+% $\begin{WithArrows}~emphase#[start-adjust=0pt, end-adjust=0pt]@
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% $\begin{WithArrows}[start-adjust=0pt, end-adjust=0pt]
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% Here is the standard behaviour since version 1.13 (the parameters
+% |start-adjust| and |end-ajust| are used with the default value $0.4$~ex). The
+% arrow is longer and the result is more aesthetic.
+%
+% \medskip
+% $\begin{WithArrows}
+% A & = (a+1)^2 \Arrow{we expand} \\
+% & = a^2 + 2a + 1
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% It's also possible to use the option |adjust| which sets both |start-adjust|
+% and |end-ajust|.
+%
+% \bigskip
+% Since the mechanism of |start-adjust| and |end-ajust| has been added in
+% version 1.13 of \pkg{witharrows}, that version is not stricty compatible with
+% older versions. However, it's possible to restore the previous behaviour
+% simply by setting |start-adjust| and |end-adjust| to $0$~pt:
+% \begin{Verbatim}
+% \WithArrowsOptions{adjust = 0pt}
+% \end{Verbatim}
+%
+% \bigskip
+% \subsection{Footnotes in the environments of witharrows}
+%
+% If you want to put footnotes in an environment |{WithArrows}| or
+% |{DispWithArrows}|, you can use a pair |\footnotemark|--|\footnotetext|.
+%
+% \smallskip
+% It's also possible to extract the footnotes with the help of the package
+% \pkg{footnote} or the package \pkg{footnotehyper}.
+%
+% \smallskip
+% If \pkg{witharrows} is loaded with the option |footnote| (with
+% |\usepackage[footnote]{witharrows}| or with |\PassOptionsToPackage|), the
+% package \pkg{footnote} is loaded (if it is not yet loaded) and it is used to
+% extract the footnotes.
+%
+% \smallskip
+% If \pkg{witharrows} is loaded with the option |footnotehyper|, the package
+% \pkg{footnotehyper} is loaded (if it is not yet loaded) ant it is used to
+% extract footnotes.
+%
+% \smallskip
+% Caution: The packages \pkg{footnote} and \pkg{footnotehyper} are incompatible.
+% The package \pkg{footnotehyper} is the successor of the package \pkg{footnote}
+% and should be used preferently. The package \pkg{footnote} has some drawbacks,
+% in particular: it must be loaded after the package \pkg{xcolor} and it is not
+% perfectly compatible with \pkg{hyperref}.
+%
+% \medskip
+% In this document, the package \pkg{witharrows} has been loaded with the option
+% |footnotehyper| and we give an example with a footnote in the label of an
+% arrow:
+%
+% \smallskip
+% $\begin{WithArrows}
+% A & = (a+b)^2
+% \Arrow{We expand\,\footnote{A footnote.}} \\
+% & = a^2+b^2+2ab
+% \end{WithArrows}$
+%
+% \bigskip
+% \subsection{Option no-arrows}
+%
+% The option |no-arrows| is a convenience given to the user. With this option
+% the arrows are not drawn. However, an analyse of the arrows is done and some
+% errors can be raised, for example if an arrow would arrive after the last row
+% of the environment.
+%
+%
+% \bigskip
+% \subsection{Note for developpers}
+%
+% If you want to construct an environment upon an environment of
+% \pkg{witharrows}, we recommand to call the environment with the construction
+% |\WithArrows|-|\endWithArrows| or |\DispWithArrows|-|\endDispWithArrows| (and
+% not |\begin{WithArrows}|-|\end{WithArrows}|, etc.).
+%
+% \smallskip
+% By doing so, the error messages generated by \pkg{witharrows} will (usually)
+% mention the name of your environment and they will be easier to understand by
+% the final user.
+%
+% \smallskip
+% By example, you can define an environment |{DWA}| which is an alias of
+% |{DispWithArrows}|:
+% \begin{BVerbatim}
+% \NewDocumentEnvironment {DWA} {} {\DispWithArrows}{\endDispWithArrows}
+% \end{BVerbatim}
+%
+% \smallskip
+% If you use this environment |{DWA}| in math mode, you will have the following
+% error message:
+%
+% \begin{BVerbatim}
+% The environment {DWA} should be used only outside math mode.
+% \end{BVerbatim}
+%
+% \interitem
+% Another example is the definition of the environment |{DispWithArrows*}|
+% internally in the package \pkg{witharrows} by the following code:
+% \begin{Verbatim}
+% \NewDocumentEnvironment {DispWithArrows*} {}
+% {\WithArrowsOptions{notag}%
+% \DispWithArrows}
+% {\endDispWithArrows}
+% \end{Verbatim}
+%
+%
+%
+% \section{Examples}
+%
+% \subsection{\textbackslash MoveEqLeft}
+%
+% It's possible to use |\MoveEqLeft| of \pkg{mathtools}. Don't forget that
+% |\MoveEqLeft| has also the value of an ampersand (|&|). That's important for the
+% placement of an eventual command |\Arrow|.
+%
+%
+%
+% \begin{Verbatim}[formatcom=\small\color{gray}]
+% $\begin{WithArrows}[interline=0.5ex]
+% ~emphase#\MoveEqLeft@ \arccos(x) = \arcsin \frac45 + \arcsin \frac5{13}
+% \Arrow{because both are in $[-\frac{\pi}2,\frac{\pi}2]$} \\
+% & \Leftrightarrow x = \sin\left(\arcsin\frac45 + \arcsin\frac5{13}\right) \\
+% & \Leftrightarrow x = \frac45\cos\arcsin\frac5{13} + \frac5{13} \cos\arcsin\frac45
+% \Arrow{$\forall x \in [-1,1], \cos(\arcsin x) = \sqrt{1-x^2}$} \\
+% & \Leftrightarrow x = \frac45\sqrt{1-\bigl(\frac5{13}\bigr)^2}
+% + \frac5{13}\sqrt{1-\bigl(\frac45\bigr)^2}
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+%
+% \medskip
+% $\begin{WithArrows}[interline=0.5ex]
+% \MoveEqLeft \arccos(x) = \arcsin \frac45 + \arcsin \frac5{13}
+% \Arrow{because both are in $[-\frac{\pi}2,\frac{\pi}2]$} \\
+% & \Leftrightarrow x = \sin\left(\arcsin\frac45 + \arcsin\frac5{13}\right) \\
+% & \Leftrightarrow x = \frac45\cos\arcsin\frac5{13} + \frac5{13} \cos\arcsin\frac45
+% \Arrow{$\forall x \in [-1,1], \cos(\arcsin x) = \sqrt{1-x^2}$} \\
+% & \Leftrightarrow x = \frac45\sqrt{1-\bigl(\frac5{13}\bigr)^2}
+% + \frac5{13}\sqrt{1-\bigl(\frac45\bigr)^2}
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% \subsection{Modifying the shape of the nodes}
+%
+% It's possible to change the shape of the labels, which are Tikz nodes, by
+% modifying the key ``|every node|'' of Tikz.
+%
+% \begin{Verbatim}
+% \begin{WithArrows}%
+% [format = c,
+% interline = 4mm,
+% tikz = {~emphase#every node/.style = {circle,@
+% ~emphase# draw,@
+% ~emphase# auto = false,@
+% ~emphase# fill = gray!50,@
+% ~emphase# inner sep = 1pt,@
+% ~emphase# font = \tiny}@}]
+% 3 (2x+4) = 6 \Arrow{$\div 3$} \\
+% 2x+4 = 2 \Arrow{$-4$} \\
+% 2x = -2 \Arrow{$\div 2$} \\
+% 2x = -1
+% \end{WithArrows}
+% \end{Verbatim}
+%
+% \[\begin{WithArrows}[%
+% format = c,
+% interline = 4mm,
+% tikz = {every node/.style = {circle,
+% draw,
+% auto = false,
+% fill = gray!50,
+% inner sep = 1pt,
+% font = \tiny}}]
+% 3 (2x+4) = 6 \Arrow{$\div 3$} \\
+% 2x+4 = 2 \Arrow{$-4$} \\
+% 2x = -2 \Arrow{$\div 2$} \\
+% 2x = -1
+% \end{WithArrows}\]
+%
+%
+% \bigskip
+% \subsection{Examples with the option tikz-code}
+%
+% We recall that the option |tikz-code| is the Tikz code used by \pkg{witharrows}
+% to draw the arrows.\footnote{If an environment |{DispWithArrows}| or
+% |{DispWithArrows*}| is used with the option |wrap-lines|, the value of the
+% option |tikz-code| is not used for this environment (but is used for the
+% environments nested inside).}
+%
+% \smallskip
+% The value by defaut of |tikz-code| is \verb|\draw (#1) to node {#3} (#2) ;|
+% where the three markers |#1|, |#2| and |#3| represent the start row, the end
+% row and the label of the arrow.
+%
+%
+% \bigskip
+% \subsubsection{Example 1}
+% In the following example, we define the value of |tikz-code| with two
+% instructions |\path| : the first instruction draws the arrow itself and the
+% second puts the label in a Tikz node in the rectangle delimited by the arrow.
+%
+% \begin{Verbatim}
+% \begin{DispWithArrows*}%
+% [displaystyle,
+% ygap = 2mm,
+% ystart = 0mm,
+% ~emphase#tikz-code = {\draw (~#1) -- ++(4.5cm,0) |- (~#2) ;@
+% ~emphase# \path (~#1) -- (~#2) @
+% ~emphase# node[text width = 4.2cm, right, midway] {~#3} ;}@]
+% S_n
+% & = \frac1n \sum_{k=0}^{n-1}\cos\bigl(\tfrac{\pi}2\cdot\tfrac kn\bigr)
+% ...........
+% \end{Verbatim}
+%
+%
+% \bigskip
+% \begin{DispWithArrows*}[
+% displaystyle,
+% ygap = 2mm,
+% ystart = 0mm,
+% tikz-code = {\draw (#1) -- ++(4.5cm,0) |- (#2) ;
+% \path (#1) -- (#2)
+% node[text width = 4.2cm, right, midway] {#3} ;}]
+% S_n
+% & = \frac1n \sum_{k=0}^{n-1}\cos\bigl(\tfrac{\pi}2\cdot\tfrac kn\bigr)
+% \Arrow{$\cos x = \Re(e^{ix})$}\\
+% & = \frac1n\sum_{k=0}^{n-1} \Re\left(e^{i\frac{k\pi}{2n}}\right)
+% \Arrow{$\Re(z+z')=\Re(z)+\Re(z')$}\\
+% & = \frac1n \Re\left(\sum_{k=0}^{n-1} e^{i\frac{k\pi}{2n}}\right)
+% \Arrow{$\exp$ is a morphism for $\times$ et $+$} \\
+% & = \frac1n \Re \left(\sum_{k=0}^{n-1}\bigl(e^{i\frac{\pi}{2n}}\bigr)^k\right)
+% \Arrow{sum of terms of a geometric progression of ratio $e^{i\frac{2\pi}n}$}\\
+% & = \frac1n \Re \left( \frac{1-\bigl(e^{i\frac{\pi}{2n}}\bigr)^n}{1-e^{i\frac{\pi}{2n}}}\right)\\
+% & = \frac1n \Re \left(\frac{1-i}{1-e^{i\frac{\pi}{2n}}}\right)
+% \end{DispWithArrows*}
+%
+% \bigskip
+% \subsubsection{Example 2}
+%
+% \label{example-WithArrowsRightX}
+% It's possible to modify the previous example to have the ``|text width|''
+% automatically computed with the right margin (in a way similar as the
+% |wrap-lines| option) in the environments |{DispWithArrows}| and
+% |{DispWithArrows*}|. In the definition of |tikz-code|, we use the command
+% |\WithArrowsRightX| which is the $x$-value of the right margin of the current
+% composition box (it's a TeX command and not a dimension). For lisibility, we
+% use a style. This example requires the Tikz library \pkg{calc}.
+%
+% \begin{Verbatim}
+% \WithArrowsNewStyle{MyStyle}
+% {displaystyle,
+% ygap = 2mm,
+% xoffset = 0pt,
+% ystart = 0mm,
+% tikz-code = {\path let \p1 = (~#~#1)
+% in (~#~#1)
+% -- node [anchor = west,
+% text width = {~emphase#\WithArrowsRightX@ - \x1 - 0.5 em}]
+% {~#~#3}
+% (~#~#2) ;
+% \draw let \p1 = (~#~#1)
+% in (~#~#1) -- ++(~emphase#\WithArrowsRightX@ - \x1,0) |- (~#~#2) ; }}
+% \end{Verbatim}
+%
+% \begin{Verbatim}
+%\begin{DispWithArrows}[MyStyle]
+% S_n
+% & = \frac1n \sum_{k=0}^{n-1}\cos\bigl(\tfrac{\pi}2\cdot\tfrac kn\bigr)
+% \Arrow{$\cos x = \Re(e^{ix})$}\\
+% ...........
+% \end{Verbatim}
+%
+% \WithArrowsNewStyle{MyStyle}
+% {displaystyle,
+% ygap = 2mm,
+% xoffset = 0pt,
+% ystart = 0mm,
+% tikz-code = {\path let \p1 = (##1)
+% in (##1)
+% -- node [anchor = west,
+% text width = {\WithArrowsRightX - \x1 - 0.5 em}] {##3}
+% (##2) ;
+% \draw let \p1 = (##1)
+% in (##1) -- ++(\WithArrowsRightX - \x1,0) |- (##2) ; }}
+%
+%\begin{DispWithArrows}[MyStyle]
+% S_n
+% & = \frac1n \sum_{k=0}^{n-1}\cos\bigl(\tfrac{\pi}2\cdot\tfrac kn\bigr)
+% \Arrow{$\cos x = \Re(e^{ix})$}\\
+% & = \frac1n\sum_{k=0}^{n-1} \Re\left(e^{i\frac{k\pi}{2n}}\right)
+% \Arrow{$\Re(z+z')=\Re(z)+\Re(z')$}\\
+% & = \frac1n \Re\left(\sum_{k=0}^{n-1} e^{i\frac{k\pi}{2n}}\right)
+% \Arrow{$\exp$ is a morphism for $\times$ et $+$} \\
+% & = \frac1n \Re \left(\sum_{k=0}^{n-1}\bigl(e^{i\frac{\pi}{2n}}\bigr)^k\right)
+% \Arrow{sum of terms of a geometric progression of ratio $e^{i\frac{2\pi}n}$}\\
+% & = \frac1n \Re \left( \frac{1-\bigl(e^{i\frac{\pi}{2n}}\bigr)^n}{1-e^{i\frac{\pi}{2n}}}\right)\\
+% & = \frac1n \Re \left(\frac{1-i}{1-e^{i\frac{\pi}{2n}}}\right)
+% \end{DispWithArrows}
+%
+%
+%
+% \bigskip
+% \subsubsection{Example 3}
+%
+% In the following example, we change the shape of the arrow depending on whether
+% the start row is longer than the end row or not. This example requires the
+% Tikz library \pkg{calc}.
+%
+% \begin{Verbatim}
+% \begin{WithArrows}[ll,interline=5mm,xoffset=5mm,
+% ~emphase#tikz-code = {\draw[rounded corners,@
+% ~emphase# every node/.style = {circle,@
+% ~emphase# draw,@
+% ~emphase# auto = false,@
+% ~emphase# inner sep = 1pt,@
+% ~emphase# fill = gray!50,@
+% ~emphase# font = \tiny }]@
+% ~emphase# let \p1 = (~#1),@
+% ~emphase# \p2 = (~#2)@
+% ~emphase# in \ifdim \x1 > \x2@
+% ~emphase# (\p1) -- node {~#3} (\x1,\y2) -- (\p2)@
+% ~emphase# \else@
+% ~emphase# (\p1) -- (\x2,\y1) -- node {~#3} (\p2)@
+% ~emphase# \fi ;}@]
+% E & \Longleftrightarrow \frac{(x+4)}3 + \frac{5x+3}5 = 7
+% \Arrow{$\times 15$}\\
+% & \Longleftrightarrow 5(x+4) + 3(5x+3) = 105 \\
+% & \Longleftrightarrow 5x+20 + 15x+9 = 105 \\
+% & \Longleftrightarrow 20x+29 = 105
+% \Arrow{$-29$}\\
+% & \Longleftrightarrow 20x = 76
+% \Arrow{$\div 20$}\\
+% & \Longleftrightarrow x = \frac{38}{10}
+% \end{WithArrows}
+% \end{Verbatim}
+%
+%
+% \[\begin{WithArrows}[ll,interline=5mm,xoffset=5mm,
+% tikz-code = {\draw[rounded corners,
+% every node/.style = {circle,
+% draw,
+% auto = false,
+% inner sep = 1pt,
+% fill = gray!50,
+% font = \tiny}]
+% let \p1 = (#1),
+% \p2 = (#2)
+% in \ifdim \x1 > \x2
+% (\p1) -- node {#3} (\x1,\y2) -- (\p2)
+% \else
+% (\p1) -- (\x2,\y1) -- node {#3} (\p2)
+% \fi ;}]
+% E & \Longleftrightarrow \frac{(x+4)}3 + \frac{5x+3}5 = 7
+% \Arrow{$\times 15$}\\
+% & \Longleftrightarrow 5(x+4) + 3(5x+3) = 105 \\
+% & \Longleftrightarrow 5x+20 + 15x+9 = 105 \\
+% & \Longleftrightarrow 20x+29 = 105
+% \Arrow{$-29$}\\
+% & \Longleftrightarrow 20x = 76
+% \Arrow{$\div 20$}\\
+% & \Longleftrightarrow x = \frac{38}{10}
+% \end{WithArrows}\]
+%
+%
+%
+% \subsection{Automatic numbered loop}
+%
+% Assume we want to draw a loop of numbered arrows. In this purpose, it's
+% possible to write a dedicated command |\NumberedLoop| which will do the job
+% when used in |code-after|. In the following example, we write this command with
+% |\NewDocumentCommand| of \pkg{xparse} and |\foreach| of \pkg{pgffor} (both
+% packages are loaded when \pkg{witharrows} is loaded).
+%
+% \begin{Verbatim}
+% \NewDocumentCommand \NumberedLoop {}
+% {\foreach \j in {2,...,\WithArrowsNbLines}
+% { \pgfmathtruncatemacro{\i}{\j-1}
+% \Arrow[rr]{\i}{\j}{\i} }
+% \Arrow[rr,xoffset=1cm,tikz=<-]{1}{\WithArrowsNbLines}{\WithArrowsNbLines}}
+% \end{Verbatim}
+%
+% The command |\WithArrowsNbLines| is a command available in |code-after| which
+% gives the total number of lines (=rows) of the current environment (it's a
+% command and not a counter).
+%
+%
+% \bigskip
+% \begin{Verbatim}
+% $\begin{WithArrows}[~emphase#code-after = \NumberedLoop@]
+% a.\;& f \text{ est continuous on } E \\
+% b.\;& f \text{ est continuous in } 0 \\
+% c.\;& f \text{ is bounded on the unit sphere} \\
+% d.\;& \exists K > 0\quad \forall x \in E\quad \|f(x)\| \le K \|x\| \\
+% e.\;& f \text{ is lipschitzian}
+% \end{WithArrows}$
+% \end{Verbatim}
+%
+% \bigskip
+% \begin{scope}
+% \NewDocumentCommand \NumberedLoop {}
+% {\foreach \j in {2,...,\WithArrowsNbLines}
+% { \pgfmathtruncatemacro{\i}{\j-1}
+% \Arrow[rr]{\i}{\j}{\i} }
+% \Arrow[rr,xoffset=1cm,tikz=<-]{1}{\WithArrowsNbLines}{\WithArrowsNbLines}}
+%
+%
+% $\begin{WithArrows}[code-after = \NumberedLoop]
+% a.\;& f \text{ est continuous on } E \\
+% b.\;& f \text{ est continuous in } 0 \\
+% c.\;& f \text{ is bounded on the unit sphere} \\
+% d.\;& \exists K > 0\quad \forall x \in E\quad \|f(x)\| \le K \|x\| \\
+% e.\;& f \text{ is lipschitzian}
+% \end{WithArrows}$
+%
+%
+% \bigskip
+% As usual, it's possible to change the characteristic of both arrows and nodes
+% with the option |tikz|. However, if we want to change the style to have, for
+% example, numbers in parenthesis, the best way is to change the value of
+% |tikz-code|:
+%
+% \begin{Verbatim}
+% tikz-code = {\draw (~#1) to node {\footnotesize (~#3)} (~#2) ;}
+% \end{Verbatim}
+%
+% \WithArrowsOptions{tikz-code = {\draw (#1) to node {\footnotesize (#3)} (#2) ;}}
+%
+% $\begin{WithArrows}[code-after = \NumberedLoop]
+% a.\;& f \text{ est continuous on } E \\
+% b.\;& f \text{ est continuous in } 0 \\
+% c.\;& f \text{ is bounded on the unit sphere} \\
+% d.\;& \exists K > 0\quad \forall x \in E\quad \|f(x)\| \le K \|x\| \\
+% e.\;& f \text{ is lipschitzian}
+% \end{WithArrows}$
+%
+% \end{scope}
+%
+% \vspace{2cm}
+%
+% \section{Implementation}
+%
+% \subsection{Declaration of the package and extensions loaded}
+%
+%
+% First, \pkg{tikz} and some Tikz libraries are loaded before the
+% |\ProvidesExplPackage|. They are loaded this way because |\usetikzlibrary| in
+% |expl3| code fails.\footnote{cf.
+% |tex.stackexchange.com/questions/57424/using-of-usetikzlibrary-in-an-expl3-package-fails|}
+%
+% \begin{macrocode}
+%<@@=wa>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*LaTeX>
+\RequirePackage{tikz}
+\RequirePackage{expl3}[2019/02/15]
+%</LaTeX>
+%<*plain-TeX>
+\input tikz.tex
+\input expl3-generic.tex
+%</plain-TeX>
+\usetikzlibrary{arrows.meta,bending}
+% \end{macrocode}
+%
+% \bigskip
+% Then, we can give the traditional declaration of a package written with
+% |expl3|:
+% \begin{macrocode}
+%<*LaTeX>
+\RequirePackage{l3keys2e}
+\ProvidesExplPackage
+ {witharrows}
+ {\myfiledate}
+ {\myfileversion}
+ {Draws arrows for explanations on the right}
+% \end{macrocode}
+%
+% \bigskip
+% The package \pkg{xparse} will be used to define the environments
+% |{WithArrows}|, |{DispWithArrows}|, |{DispWithArrows*}| and the commands
+% |\Arrow|, |\WithArrowsOptions| and |\WithArrowsNewStyle|.
+% \begin{macrocode}
+\RequirePackage { xparse } [ 2018-10-17 ]
+%</LaTeX>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*plain-TeX>
+\ExplSyntaxOn
+\catcode `\@ = 11
+%</plain-TeX>
+% \end{macrocode}
+%
+% \bigskip
+% \subsection{The packages footnote and footnotehyper}
+%
+% A few options can be given to the package \pkg{witharrows} when it is loaded
+% (with |\usepackage|, |\RequirePackage| or |\PassOptionsToPackage|). Currently
+% (version \myfileversion), there are two such options: |footnote| and
+% |footnotehyper|. With the option |footnote|, \pkg{witharrows} loads
+% \pkg{footnote} and uses it to extract the footnotes from the environments
+% |{WithArrows}|. Idem for the option |footnotehyper|.
+%
+% \medskip
+% The boolean |\g_@@_footnotehyper_bool| will indicate if the option
+% |footnotehyper| is used.
+% \begin{macrocode}
+%<*LaTeX>
+\bool_new:N \g_@@_footnotehyper_bool
+% \end{macrocode}
+%
+% \medskip
+% The boolean |\g_@@_footnote_bool| will indicate if the option |footnote| is
+% used, but quicky, it will also be set to |true| if the option |footnotehyper|
+% is used.
+% \begin{macrocode}
+\bool_new:N \g_@@_footnote_bool
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_msg_new:nn { \msg_new:nnn { witharrows } }
+\cs_new_protected:Npn \@@_msg_new:nnn { \msg_new:nnnn { witharrows } }
+\cs_new_protected:Npn \@@_msg_redirect_name:nn
+ { \msg_redirect_name:nnn { witharrows } }
+\cs_new_protected:Npn \@@_error:n { \msg_error:nn { witharrows } }
+\cs_new_protected:Npn \@@_warning:n { \msg_error:nn { witharrows } }
+\cs_new_protected:Npn \@@_fatal:n { \msg_fatal:nn { witharrows } }
+\cs_new_protected:Npn \@@_error:nn { \msg_error:nnn { witharrows } }
+\cs_generate_variant:Nn \@@_error:nn { n x }
+% \end{macrocode}
+%
+% \medskip
+% We define a set of keys |WithArrows/package| for these options.
+% \begin{macrocode}
+%<*LaTeX>
+\keys_define:nn { WithArrows / package }
+ {
+ footnote .bool_gset:N = \g_@@_footnote_bool ,
+ footnotehyper .bool_gset:N = \g_@@_footnotehyper_bool ,
+ unknown .code:n =
+ \@@_fatal:n { Option~unknown~for~package }
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Option~unknown~for~package }
+ {
+ You~can't~use~the~option~'\l_keys_key_tl'~when~loading~the~
+ package~witharrows.~Try~to~use~the~command~
+ \token_to_str:N\WithArrowsOptions.
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% We process the options when the package is loaded (with |\usepackage|).
+% \begin{macrocode}
+\ProcessKeysOptions { WithArrows / package }
+% \end{macrocode}
+%
+%
+% \medskip
+% \begin{macrocode}
+\@@_msg_new:nn { Option~incompatible~with~Beamer }
+ {
+ The~option~'\l_keys_key_tl'\ is~incompatible~
+ with~Beamer~because~Beamer~has~its~own~system~to~extract~footnotes.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { footnote~with~footnotehyper~package }
+ {
+ You~can't~use~the~option~'footnote'~because~the~package~
+ footnotehyper~has~already~been~loaded.~
+ If~you~want,~you~can~use~the~option~'footnotehyper'~and~the~footnotes~
+ within~the~environments~of~witharrows~will~be~extracted~with~the~tools~
+ of~the~package~footnotehyper.\\
+ If~you~go~on,~the~package~footnote~won't~be~loaded.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { footnotehyper~with~footnote~package }
+ {
+ You~can't~use~the~option~'footnotehyper'~because~the~package~
+ footnote~has~already~been~loaded.~
+ If~you~want,~you~can~use~the~option~'footnote'~and~the~footnotes~
+ within~the~environments~of~witharrows~will~be~extracted~with~the~tools~
+ of~the~package~footnote.\\
+ If~you~go~on,~the~package~footnotehyper~won't~be~loaded.
+ }
+% \end{macrocode}
+%
+% \medskip
+% \begin{macrocode}
+\bool_if:NT \g_@@_footnote_bool
+ {
+ \@ifclassloaded { beamer }
+ { \msg_info:nn { witharrows } { Option~incompatible~with~Beamer } }
+ {
+ \@ifpackageloaded { footnotehyper }
+ { \@@_error:n { footnote~with~footnotehyper~package } }
+ { \usepackage { footnote } }
+ }
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\bool_if:NT \g_@@_footnotehyper_bool
+ {
+ \@ifclassloaded { beamer }
+ { \@@_info:n { Option~incompatible~with~Beamer } }
+ {
+ \@ifpackageloaded { footnote }
+ { \@@_error:n { footnotehyper~with~footnote~package } }
+ { \usepackage { footnotehyper } }
+ }
+ \bool_gset_true:N \g_@@_footnote_bool
+ }
+% \end{macrocode}
+% The flag |\g_@@_footnote_bool| is raised and so, we will only have to test
+% |\g_@@_footnote_bool| in order to know if we have to insert an environnement
+% |{savenotes}| (the |\begin{savenotes}| is in |\@@_pre_halign:n| and
+% |\end{savenotes}| at the end of the environments |{WithArrows}| and
+% |{DispWithArrows}|).
+%
+% \bigskip
+% \subsection{The class option leqno}
+%
+% The boolean |\c_@@_leqno_bool| will indicate if the class option |leqno| is
+% used. When this option is used in LaTeX, the command |\@eqnnum| is redefined
+% (as one can see in the file |leqno.clo|). That's enough to put the labels on
+% the left in our environments |{DispWithArrows}| and |{DispWithArrows*}|.
+% However, that's not enough when our option |wrap-lines| is used. That's why we
+% have to know if this option is used as a class option. With the following
+% programmation, |leqno| \emph{can't} be given as an option of \pkg{witharrows}
+% (by design).
+% \begin{macrocode}
+\bool_new:N \c_@@_leqno_bool
+\DeclareOption { leqno } { \bool_set_true:N \c_@@_leqno_bool }
+\DeclareOption* { }
+\ProcessOptions*
+%</LaTeX>
+% \end{macrocode}
+%
+%
+%
+% \bigskip
+% \subsection{Some technical definitions}
+%
+%
+% \begin{macrocode}
+\cs_generate_variant:Nn \tl_put_right:Nn { N v }
+\cs_generate_variant:Nn \seq_set_split:Nnn { N x x }
+% \end{macrocode}
+%
+% \medskip
+% We create booleans in order to know if some packages are loaded. For example,
+% for the package \pkg{amsmath}, the boolean is called
+% |\c_@@_amsmath_loaded_bool|.\footnote{It's not possible to use
+% |\@ifpackageloaded| in the core of the functions because |\@ifpackageloaded|
+% is available only in the preamble.}
+% \begin{macrocode}
+\AtBeginDocument
+ {
+ \clist_map_inline:nn
+ {
+ amsmath, amsthm, autonum, cleveref, hyperref, mathtools, showlabels,
+ typedref, unicode-math, varwidth
+ }
+ {
+ \bool_new:c { c_@@_#1_loaded_bool }
+%<*LaTeX>
+ \@ifpackageloaded { #1 }
+ { \bool_set_true:c { c_@@_#1_loaded_bool } }
+ { }
+%</LaTeX>
+%<*plain-TeX>
+ \bool_set_false:c { c_@@_#1_loaded_bool }
+%</plain-TeX>
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% We define a command |\@@_strcmp:nn| to compare two token lists. It will be
+% available whether the engine is pdfTeX, XeTeX or LuaTeX.
+% \begin{macrocode}
+\sys_if_engine_luatex:TF
+ {
+ \cs_new_protected:Npn \@@_strcmp:nn #1 #2
+ { \lua_now:e { l3kernel.strcmp('#1','#2') } }
+ }
+ {
+ \cs_new_protected:Npn \@@_strcmp:nn #1 #2
+ { \pdftex_strcmp:D { #1 } { #2 } }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% We can now define a command |\@@_sort_seq:N| which will sort a sequence.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_sort_seq:N #1
+ {
+ \seq_sort:Nn #1
+ {
+ \int_compare:nNnTF
+ {
+ \@@_strcmp:nn
+ { \str_lower_case:n { ##1 } }
+ { \str_lower_case:n { ##2 } }
+ }
+ > 0
+ \sort_return_swapped:
+ \sort_return_same:
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The following command converts each item of a sequence from |tl| to |str|. It
+% will be used when creating list of keys (a key name is always a |str|).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_convert_to_str_seq:N #1
+ {
+ \seq_clear:N \l_tmpa_seq
+ \seq_map_inline:Nn #1
+ {
+ \seq_put_left:Nx \l_tmpa_seq { \tl_to_str:n { ##1 } }
+ }
+ \seq_set_eq:NN #1 \l_tmpa_seq
+ }
+\cs_new_protected:Npn \@@_set_seq_of_str_from_clist:Nn #1 #2
+ {
+ \seq_set_from_clist:Nn #1 { #2 }
+ \@@_convert_to_str_seq:N #1
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_save:N| saves a \pkg{expl3} variable by creating a global
+% version of the variable. For a variable named |\l_|\texttt{\slshape
+% name}|_|\texttt{\slshape type}, the corresponding global variable will be
+% named |\g_|\texttt{\slshape name}|_|\texttt{\slshape type}. The type of the
+% variable is determinated by the suffix \texttt{\slshape type} and is used to
+% apply the corresponding \pkg{expl3} commands.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_save:N #1
+ {
+ \seq_set_split:Nxx \l_tmpa_seq
+ { \char_generate:nn { `_ } { 12 } }
+ { \cs_to_str:N #1 }
+ \seq_pop_left:NN \l_tmpa_seq \l_tmpa_tl
+% \end{macrocode}
+% The string |\l_tmpa_str| will contains the \emph{type} of the variable.
+% \begin{macrocode}
+ \str_set:Nx \l_tmpa_str { \seq_item:Nn \l_tmpa_seq { -1 } }
+ \use:c { \l_tmpa_str _if_exist:cF }
+ { g _\seq_use:Nnnn \l_tmpa_seq _ _ _ }
+ {
+ \use:c { \l_tmpa_str _new:c }
+ { g _\seq_use:Nnnn \l_tmpa_seq _ _ _ }
+ }
+ \use:c { \l_tmpa_str _gset_eq:cN }
+ { g _\seq_use:Nnnn \l_tmpa_seq _ _ _ } #1
+ }
+% \end{macrocode}
+%
+% \medskip
+% The command |\@@_restore:N| affects to the \pkg{expl3} variable the value of
+% the (previously) set value of the corresponding \emph{global} variable.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_restore:N #1
+ {
+ \seq_set_split:Nxx \l_tmpa_seq
+ { \char_generate:nn { `_ } { 12 } }
+ { \cs_to_str:N #1 }
+ \seq_pop_left:NN \l_tmpa_seq \l_tmpa_tl
+ \str_set:Nx \l_tmpa_str { \seq_item:Nn \l_tmpa_seq { -1 } }
+ \use:c { \l_tmpa_str _set_eq:Nc }
+ #1 { g_\seq_use:Nnnn \l_tmpa_seq _ _ _ }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% We define a Tikz style |@@_node_style| for the |l|-nodes and |r|-nodes that
+% will be created in the |\halign|. These nodes are Tikz nodes of shape
+% ``rectangle'' but with zero width. An arrow between two nodes starts from the
+% \emph{south} anchor of the first node and arrives at the \emph{north} anchor
+% of the second node.
+% \begin{macrocode}
+\tikzset
+ {
+ @@_node_style / .style =
+ {
+ above = \l_@@_ystart_dim ,
+ inner~sep = \c_zero_dim ,
+ minimum~width = \c_zero_dim ,
+ minimum~height = \l_@@_ygap_dim
+ }
+ }
+% \end{macrocode}
+% If the user uses the option |show-nodes| (it's a \pkg{l3keys} option), the
+% Tikz options |draw| and |red| will be appended to this style. This feature may
+% be useful for debugging.\footnote{The |v|-nodes, created near the end of line
+% in |{DispWithArrows}| and |{DispWithArrows*}| are not shown with the option
+% |show-nodes|.}
+%
+%
+% \bigskip
+% The style |@@_standard| is loaded in standard in the |{tikzpicture}| we need.
+% The names of the nodes are prefixed by |wa| (by security) but also by a prefix
+% which is the position-in-the-tree of the nested environments.
+% \begin{macrocode}
+\tikzset
+ {
+ @@_standard / .style =
+ {
+ remember~picture ,
+ overlay ,
+ name~prefix = wa - \l_@@_prefix_str -
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% We also define a style for the tips of arrow. The final user of the extension
+% \pkg{witharrows} will use this style if he wants to draw an arrow directly
+% with a Tikz command in his document (probably using the Tikz nodes created by
+% |{WithArrows}| in the |\halign|).
+% \begin{macrocode}
+\tikzset
+ {
+ WithArrows / arrow / tips / .style =
+ { > = { Straight~Barb [ scale = 1.2 , bend ] } }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The style |WithArrows/arrow| will be used to draw the arrows (more precisely,
+% it will be passed to |every~path|).
+% \begin{macrocode}
+\tikzset
+ {
+ WithArrows / arrow / .style =
+ {
+ align = left ,
+% \end{macrocode}
+%
+% We have put the option |align = left| because we want to give the user the
+% possibility of using |\\| in the labels.
+% \begin{macrocode}
+ auto = left ,
+%<*LaTeX>
+ font = \small \itshape ,
+%</LaTeX>
+ WithArrows / arrow / tips ,
+ bend~left = 45 ,
+ ->
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The option |subequations| is an option which uses the environment
+% |{subequations}| of \pkg{amsmath}. That's why, if \pkg{amsmath} is loaded, we
+% add the key |subequations| to the list of the keys available in
+% |\WithArrowsOptions| and |{DispWithArrows}|.
+% \begin{macrocode}
+%<*LaTeX>
+\AtBeginDocument
+ {
+ \bool_if:NTF \c_@@_amsmath_loaded_bool
+ {
+ \seq_put_right:Nn \l_@@_options_WithArrowsOptions_seq { subequations }
+ \seq_put_right:Nn \l_@@_options_DispWithArrows_seq { subequations }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% In order to increase the interline in the environments |{WithArrows}|,
+% |{DispWithArrows}|, etc., we will use the command |\spread@equation| of
+% \pkg{amsmath}. When used, this command becomes no-op (in the current TeX
+% group). Therefore, it will be possible to use the environments of
+% \pkg{amsmath} (e.g. |{aligned}|) in an environment |{WithArrows}|.
+%
+% Nevertheless, we want the extension \pkg{witharrows} available without
+% \pkg{amsmath}. That's why we give a definition of |\spread@equation| if
+% \pkg{amsmath} is not loaded (we put the code in a |\AtBeginDocument| because
+% the flag |\c_@@_amsmath_loaded_bool| is itself set in a |\AtBeginDocument|).
+% \begin{macrocode}
+ {
+%</LaTeX>
+ \cs_new_protected:Npn \spread@equation
+ {
+ \openup \jot
+ \cs_set_eq:NN \spread@equation \prg_do_nothing:
+ }
+%<*LaTeX>
+ }
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+\tl_new:N \l_@@_left_brace_tl
+\tl_set_eq:NN \l_@@_left_brace_tl \c_novalue_tl
+% \end{macrocode}
+%
+% \bigskip
+% \subsection{Variables}
+%
+% The boolean |\l_@@_in_WithArrows_bool| will be raised in an environment
+% |{WithArrows}| and the boolean |\l_@@_in_dispwitharrows_bool| will be raised
+% in an environment |{DispWithArrows}| or |{DispWithArrows*}|. The boolean
+% |\l_@@_in_code_after_bool| will be raised during the execution of the
+% |code-after| (option |code-after|).
+% \begin{macrocode}
+\bool_new:N \l_@@_in_WithArrows_bool
+\bool_new:N \l_@@_in_DispWithArrows_bool
+\bool_new:N \l_@@_in_code_after_bool
+% \end{macrocode}
+%
+% \bigskip
+% The following sequence is the position of the last environment |{WithArrows}|
+% in the tree of the nested environments |{WithArrows}|.
+% \begin{macrocode}
+\seq_new:N \g_@@_position_in_the_tree_seq
+\seq_gput_right:Nn \g_@@_position_in_the_tree_seq 1
+% \end{macrocode}
+%
+% \bigskip
+% The following counter will give the number of the last environment
+% |{WithArrows}| of level~$0$. This counter will be used only in the definition
+% of |\WithArrowsLastEnv|.
+% \begin{macrocode}
+\int_new:N \g_@@_last_env_int
+% \end{macrocode}
+%
+% \bigskip
+% The following integer indicates the position of the box that will be created
+% for an environment |{WithArrows}| (not an environment |{DispWithArrows}|) :
+% 0 (=|t|=|\vtop|), 1~(=|c|=|\vcenter|) or 2 (=|b|=|\vbox|).
+% \begin{macrocode}
+\int_new:N \l_@@_pos_env_int
+% \end{macrocode}
+%
+% \bigskip
+% The integer |\l_@@_pos_arrow_int| indicates the position of the arrow with the
+% following code (the option |v| is accessible only for the arrows in
+% |code-after| where the options |i|, |group| et |groups| are not available).
+%
+% \begin{center}
+% \begin{tabular}{l}
+% \begin{tabular}{@{}l*8c@{}}
+% \toprule
+% option & |lr| & |ll| & |rl| & |rr| & |v| & |i| & |groups| & |group| \\
+% \midrule
+% |\l_@@_pos_arrow_int| & $0$ & $1$ & $2$ & $3$ & $4$ & $5$ & $6$ & $7$ \\
+% \bottomrule
+% \end{tabular} \\
+% \footnotesize The option |v| can be used only in |\Arrow| in |code-after| (see
+% below).
+% \end{tabular}
+% \end{center}
+%
+% \begin{macrocode}
+\int_new:N \l_@@_pos_arrow_int
+\int_set:Nn \l_@@_pos_arrow_int 3
+% \end{macrocode}
+%
+%
+% \bigskip
+% In the |\halign| of an environment |{WithArrows}| or |{DispWithArrows}|, we
+% will have to use four counters:
+% \begin{itemize}
+% \item |\g_@@_arrow_int| to count the arrows created in the environment ;
+% \item |\g_@@_line_int| to count the lines of the |\halign| ;
+% \item |\g_@@_col_int| to count the column of the |\halign|.
+% \end{itemize}
+%
+%
+% These counters will be incremented in a cell of the |\halign| and, therefore,
+% the incrementation must be global. However, we want to be able to include a
+% |{WithArrows}| in another |{WithArrows}|. To do so, we must restore the
+% previous value of these counters at the end of an environment |{WithArrows}|
+% and we decide to manage a stack for each of these counters.
+% \begin{macrocode}
+\seq_new:N \g_@@_arrow_int_seq
+\int_new:N \g_@@_arrow_int
+\seq_new:N \g_@@_line_int_seq
+\int_new:N \g_@@_line_int
+\seq_new:N \g_@@_col_int_seq
+\int_new:N \g_@@_col_int
+% \end{macrocode}
+%
+%
+% \bigskip
+% For the environment |{DispWithArrows}|, the comma list |\l_@@_tags_clist| will
+% be the list of the numbers of lines to be tagged (with the counter |equation|
+% of LaTeX). In fact, |\l_@@_tags_clist| may contain non negative integers but
+% also three special values, |first|, |last| and |all|.
+% \begin{macrocode}
+%<*LaTeX>
+\clist_new:N \l_@@_tags_clist
+\clist_set:Nn \l_@@_tags_clist { all }
+% \end{macrocode}
+%
+% \bigskip
+% During the execution of an environment |{DispWithArrows}|, if a row must be
+% tagged, the (local) value of |\l_@@_tags_clist| will be put (by convention) to
+% |all|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_test_if_to_tag:
+ {
+ \clist_if_in:NVT \l_@@_tags_clist \g_@@_line_int
+ { \clist_set:Nn \l_@@_tags_clist { all } }
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+%
+% \bigskip
+% If the user has given a value for the option |command-name| (at the global or
+% at the \emph{environment} level), a command with this name is defined locally
+% in the environment with meaning |\@@_Arrow|. The default value of the option
+% |command-name| is ``|Arrow|'' and thus, by default, the name of the command
+% will be |\Arrow|.
+% \begin{macrocode}
+\str_new:N \l_@@_command_name_str
+\str_set:Nn \l_@@_command_name_str { Arrow }
+% \end{macrocode}
+%
+% \bigskip
+% The string |\l_@@_string_Arrow_for_msg_str| is only a string that will be
+% displayed in some error messages. For example, if |command-name| is defined to
+% be |Explanation|, this string will contain ``|\Arrow alias \Explanation|''.
+% \begin{macrocode}
+\str_new:N \l_@@_string_Arrow_for_msg_str
+\str_set:Nx \l_@@_string_Arrow_for_msg_str { \token_to_str:N \Arrow }
+% \end{macrocode}
+%
+% \bigskip
+% The sequence |\g_@@_names_seq| will be the list of all the names of
+% environments used (via the option |name|) in the document: two environments
+% must not have the same name. However, it's possible to use the option
+% |allow-duplicate-names|.
+% \begin{macrocode}
+\seq_new:N \g_@@_names_seq
+% \end{macrocode}
+%
+% \bigskip
+% The boolean |\l_@@_sbwi_bool| corresponds to the option
+% |standard-behaviour-with-items|. Since the version 1.16 of \pkg{witharrows},
+% no vertical space is added between an |\item| of a LaTeX list and an
+% environment |{DispWithArrows}|. With the option
+% |standard-behaviour-with-items|, it's possible to restore the previous
+% behaviour (which corresponds to the standard behaviour of |{align}| of
+% \pkg{amsmath}). |\l_@@_sbwi_bool| is the boolean corresponding to this option.
+% \begin{macrocode}
+%<*LaTeX>
+\bool_new:N \l_@@_sbwi_bool
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+%<*LaTeX>
+\bool_new:N \l_@@_tag_star_bool
+\bool_new:N \l_@@_tag_next_line_bool
+\bool_new:N \l_@@_qedhere_bool
+%</LaTeX>
+\bool_new:N \l_@@_in_first_columns_bool
+\bool_new:N \l_@@_new_group_bool
+\bool_new:N \l_@@_initial_r_bool
+\bool_new:N \l_@@_final_r_bool
+\tl_new:N \l_@@_initial_tl
+\tl_new:N \l_@@_final_tl
+\int_new:N \l_@@_nb_cols_int
+% \end{macrocode}
+%
+% \bigskip
+% The string |\l_@@_format_str| will contain the \emph{format} of the array
+% which is a succession of letters |r|, |c| and |l| specifying the type of the
+% columns of the |\halign| (except the column for the labels of the equations
+% in the environment |{DispWithArrows}|).
+% \begin{macrocode}
+\str_new:N \l_@@_format_str
+% \end{macrocode}
+%
+% \bigskip
+% The option boolean corresponds to the option |subequations|.
+% \begin{macrocode}
+%<*LaTeX>
+\bool_new:N \l_@@_subequations_bool
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% \subsection{The definition of the options}
+%
+% There are four levels where options can be set:
+% \begin{itemize}
+% \item with |\usepackage[...]{witharrows}|: this level will be called
+% \emph{package} level;
+% \item with |\WithArrowsOptions{...}|: this level will be called \emph{global}
+% level\footnote{This level is called \emph{global level} but the settings done
+% by |\WithArrowsOptions| are local in the TeX sense: their scope corresponds to
+% the current TeX group.};
+% \item with |\begin{WithArrows}[...]|: this level will be called
+% \emph{environment} level;
+% \item with |\Arrow[...]| (included in |code-after|): this level will be called
+% \emph{local} level.
+% \end{itemize}
+%
+%
+% \bigskip
+% When we scan a list of options, we want to be able to raise an error if two
+% options of position (|ll|, |rl|, |i|, etc.) of the arrows are present. That's
+% why we keep the first option of position in a variable called
+% |\l_@@_previous_key_str|. The following function |\@@_eval_if_allowed:n| will
+% execute its argument only if a first key of position has not been set (and
+% raise an error elsewhere).
+%
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_eval_if_allowed:n #1
+ {
+ \str_if_empty:NTF \l_@@_previous_key_str
+ {
+ \str_set_eq:NN \l_@@_previous_key_str \l_keys_key_tl
+ #1
+ }
+ { \@@_error:n { Incompatible~options } }
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_fix_pos_option:n #1
+ { \@@_eval_if_allowed:n { \int_set:Nn \l_@@_pos_arrow_int { #1 } } }
+% \end{macrocode}
+%
+% \bigskip
+% First a set of keys that will be used at the global or environment level of
+% options.
+% \begin{macrocode}
+\keys_define:nn { WithArrows / Global }
+ {
+ ygap .dim_set:N = \l_@@_ygap_dim ,
+ ygap .value_required:n = true ,
+ ygap .initial:n = 0.4 ex ,
+ ystart .dim_set:N = \l_@@_ystart_dim ,
+ ystart .value_required:n = true ,
+ ystart .initial:n = 0.4 ex ,
+ more-columns .code:n =
+ \@@_msg_redirect_name:nn { Too~much~columns~in~WithArrows } { none } ,
+ more-columns .value_forbidden:n = true,
+ command-name .code:n =
+ \str_set:Nn \l_@@_command_name_str { #1 }
+ \str_set:Nx \l_@@_string_Arrow_for_msg_str
+ { \c_backslash_str Arrow~alias~\c_backslash_str #1 } ,
+ command-name .value_required:n = true ,
+ tikz-code .tl_set:N = \l_@@_tikz_code_tl,
+ tikz-code .initial:n = \draw~(#1)~to~node{#3}~(#2)~; ,
+ tikz-code .value_required:n = true ,
+ TikzCode .meta:n = { tikz-code = #1 } ,
+ displaystyle .bool_set:N = \l_@@_displaystyle_bool ,
+ displaystyle .default:n = true ,
+ show-nodes .code:n =
+ \tikzset { @@_node_style / .append~style = { draw , red } } ,
+ show-nodes .value_forbidden:n = true,
+ show-node-names .bool_set:N = \l_@@_show_node_names_bool ,
+ show-node-names .default:n = true ,
+ group .code:n =
+ \str_if_empty:NTF \l_@@_previous_key_str
+ {
+ \str_set:Nn \l_@@_previous_key_str { group }
+ \seq_remove_all:Nn \l_@@_options_Arrow_seq { xoffset }
+ \int_set:Nn \l_@@_pos_arrow_int 7
+ }
+ { \@@_error:n { Incompatible~options } } ,
+ group .value_forbidden:n = true ,
+ groups .code:n =
+ \str_if_empty:NTF \l_@@_previous_key_str
+ {
+ \str_set:Nn \l_@@_previous_key_str { groups }
+ \seq_if_in:NnF \l_@@_options_Arrow_seq { new-group }
+ { \seq_put_right:Nn \l_@@_options_Arrow_seq { new-group } }
+ \seq_remove_all:Nn \l_@@_options_Arrow_seq { xoffset }
+ \int_set:Nn \l_@@_pos_arrow_int 6
+ }
+ { \@@_error:n { Incompatible~options } } ,
+ groups .value_forbidden:n = true ,
+ tikz .code:n = \tikzset { WithArrows / arrow / .append~style = { #1 } } ,
+ tikz .initial:n = \c_empty_tl ,
+ tikz .value_required:n = true ,
+ rr .value_forbidden:n = true ,
+ rr .code:n = \@@_fix_pos_option:n 3 ,
+ ll .value_forbidden:n = true ,
+ ll .code:n = \@@_fix_pos_option:n 1 ,
+ rl .value_forbidden:n = true ,
+ rl .code:n = \@@_fix_pos_option:n 2 ,
+ lr .value_forbidden:n = true ,
+ lr .code:n = \@@_fix_pos_option:n 0 ,
+ i .value_forbidden:n = true ,
+ i .code:n = \@@_fix_pos_option:n 5 ,
+ xoffset .dim_set:N = \l_@@_xoffset_dim ,
+ xoffset .value_required:n = true ,
+ xoffset .initial:n = 3 mm ,
+ jot .dim_set:N = \jot ,
+ jot .value_required:n = true ,
+ interline .skip_set:N = \l_@@_interline_skip ,
+ interline .value_required:n = true ,
+ start-adjust .dim_set:N = \l_@@_start_adjust_dim ,
+ start-adjust .value_required:n = true ,
+ start-adjust .initial:n = 0.4 ex ,
+ end-adjust .dim_set:N = \l_@@_end_adjust_dim ,
+ end-adjust .value_required:n = true ,
+ end-adjust .initial:n = 0.4 ex ,
+ adjust .meta:n = { start-adjust = #1 , end-adjust = #1 } ,
+ adjust .value_required:n = true ,
+% \end{macrocode}
+%
+% \medskip
+% With the option |no-arrows|, the arrows won't be drawn. However, the ``first
+% pass'' of the arrows is done and some errors may be detected. The
+% nullification of |\@@_draw_arrows:nn| is for the standard arrows and the
+% nullification of |\@@_draw_arrow:nnn| is for ``Arrow in |code-after|''.
+% \begin{macrocode}
+ no-arrows .code:n =
+ \cs_set_eq:NN \@@_draw_arrows:nn \use_none:nn
+ \cs_set_eq:NN \@@_draw_arrow:nnn \use_none:nnn ,
+ no-arrows .value_forbidden:n = true ,
+ }
+% \end{macrocode}
+%
+% \bigskip
+% Now a set of keys specific to the environments |{WithArrows}| (and not
+% |{DispWithArrow}}|). Despite its name, this set of keys will also be used in
+% |\WithArrowsOptions|.
+% \begin{macrocode}
+\keys_define:nn { WithArrows / WithArrowsSpecific }
+ {
+ t .code:n = \int_set:Nn \l_@@_pos_env_int O ,
+ t .value_forbidden:n = true ,
+ c .code:n = \int_set:Nn \l_@@_pos_env_int 1 ,
+ c .value_forbidden:n = true ,
+ b .code:n = \int_set:Nn \l_@@_pos_env_int 2 ,
+ b .value_forbidden:n = true
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The following list of the (left) extensible delimiters of LaTeX is only for
+% the validation of the key |replace-left-brace-by|.
+% \begin{macrocode}
+\clist_new:N \c_@@_extensible_delimiters_clist
+\clist_set:Nn \c_@@_extensible_delimiters_clist
+ {
+ ., \{, (, [, \lbrace, \lbrack, \lgroup, \langle, \lmoustache, \lceil, \lfloor
+ }
+%<*LaTeX>
+\AtBeginDocument
+ {
+ \bool_if:nT
+ { \c_@@_amsmath_loaded_bool || \use:c { c_@@_unicode-math_loaded_bool } }
+ {
+ \clist_put_right:Nn \c_@@_extensible_delimiters_clist { \lvert, \lVert }
+ }
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+%
+% \bigskip
+% Now a set of keys specific to the environments |{DispWithArrows}| and
+% |{DispWithArrows*}| (and not |{WithArrows}|). Despite its name, this set of
+% keys will also be used in |\WithArrowsOptions|.
+% \begin{macrocode}
+\keys_define:nn { WithArrows / DispWithArrowsSpecific }
+ {
+ fleqn .bool_set:N = \l_@@_fleqn_bool ,
+ fleqn .default:n = true ,
+ mathindent .dim_set:N = \l_@@_mathindent_dim ,
+ mathindent .value_required:n = true ,
+ mathindent .initial:n = 25 pt ,
+%<*LaTeX>
+ notag .code:n =
+ \str_if_eq:nnTF { #1 } { true }
+ { \clist_clear:N \l_@@_tags_clist }
+ { \clist_set:Nn \l_@@_tags_clist { all } } ,
+ notag .default:n = true ,
+% \end{macrocode}
+% Since the option |subequations| is an option which insert the environment
+% |{DispWithArrows}| in an environment |{subequations}| of \pkg{amsmath}, we
+% must test whether the package \pkg{amsmath} is loaded.
+% \begin{macrocode}
+ subequations .code:n =
+ \bool_if:NTF \c_@@_amsmath_loaded_bool
+ { \bool_set_true:N \l_@@_subequations_bool }
+ {
+ \@@_error:n { amsmath~not~loaded }
+ \group_begin:
+ \globaldefs = 1
+ \@@_msg_redirect_name:nn { amsmath~not~loaded } { info }
+ \group_end:
+ } ,
+ subequations .default:n = true ,
+ subequations .value_forbidden:n = true ,
+ nonumber .meta:n = notag ,
+ allow-multiple-labels .code:n =
+ \@@_msg_redirect_name:nn { Multiple~labels } { none } ,
+ allow-multiple-labels .value_forbidden:n = true ,
+ tagged-lines .code:n =
+ \clist_set:Nn \l_@@_tags_clist { #1 }
+ \clist_if_in:NnT \l_@@_tags_clist { first }
+ {
+ \clist_remove_all:Nn \l_@@_tags_clist { first }
+ \clist_put_left:Nn \l_@@_tags_clist \c_one_int
+ } ,
+ tagged-lines .value_required:n = true ,
+%</LaTeX>
+ wrap-lines .bool_set:N = \l_@@_wrap_lines_bool ,
+ wrap-lines .default:n = true ,
+ replace-left-brace-by .code:n =
+ {
+ \tl_set:Nx \l_tmpa_tl { \tl_head:n { #1 } }
+ \clist_if_in:NVTF
+ \c_@@_extensible_delimiters_clist
+ \l_tmpa_tl
+ { \tl_set:Nn \l_@@_replace_left_brace_by_tl { #1 } }
+ { \@@_error:n { Bad~value~for~replace~brace~by } }
+ } ,
+ replace-left-brace-by .initial:n = \lbrace ,
+% \end{macrocode}
+%
+% Since the version 1.16 of \pkg{witharrows}, no vertical space is added between
+% an |\item| of a LaTeX list and an environment |{DispWithArrows}|. With the
+% option |standard-behaviour-with-items|, it's possible to restore the previous
+% behaviour (which corresponds to the standard behaviour of |{align}| of
+% \pkg{amsmath}).
+% \begin{macrocode}
+%<*LaTeX>>
+ standard-behaviour-with-items .bool_set:N = \l_@@_sbwi_bool ,
+ standard-behaviour-with-items .default:n = true
+%</LaTeX>
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% Now a set of keys which will be used in all the environments (but not in
+% |\WithArrowsOptions}|).
+%
+% \begin{macrocode}
+\keys_define:nn { WithArrows / Env }
+ {
+ name .code:n =
+% \end{macrocode}
+% First, we convert the value in a |str| because the list of the names will be a
+% list of |str|.
+% \begin{macrocode}
+ \str_set:Nn \l_tmpa_str { #1 }
+ \seq_if_in:NVTF \g_@@_names_seq \l_tmpa_str
+ { \@@_error:n { Duplicate~name } }
+ { \seq_gput_left:NV \g_@@_names_seq \l_tmpa_str }
+ \str_set_eq:NN \l_@@_name_str \l_tmpa_str ,
+ name .value_required:n = true ,
+ code-before .code:n = \tl_put_right:Nn \l_@@_code_before_tl { #1 } ,
+ code-before .value_required:n = true,
+ CodeBefore .meta:n = { code-before = #1 } ,
+ code-after .code:n = \tl_put_right:Nn \l_@@_code_after_tl { #1 } ,
+ code-after .value_required:n = true ,
+ CodeAfter .meta:n = { code-after = #1 } ,
+ format .code:n =
+ \tl_if_empty:nTF { #1 }
+ { \@@_error:n { Invalid~option~format } }
+ {
+ \regex_match:nnTF { \A[rcl]*\Z } { #1 }
+ { \tl_set:Nn \l_@@_format_str { #1 } }
+ { \@@_error:n { Invalid~option~format } }
+ } ,
+ format .value_required:n = true ,
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% Now, we begin the construction of the major sets of keys, named
+% ``|WithArrows / WithArrows|'', ``|WithArrows / DispWithArrows|'' and
+% ``|WithArrows / WithArrowsOptions|''. Each of these sets of keys will be
+% completed after.
+% \begin{macrocode}
+\keys_define:nn { WithArrows }
+ {
+ WithArrows .inherit:n =
+ {
+ WithArrows / Global ,
+ WithArrows / WithArrowsSpecific ,
+ WithArrows / Env
+ } ,
+ DispWithArrows .inherit:n =
+ {
+ WithArrows / DispWithArrowsSpecific ,
+ WithArrows / Global ,
+ WithArrows / Env ,
+ } ,
+ WithArrowsOptions .inherit:n =
+ {
+ WithArrows / Global ,
+ WithArrows / WithArrowsSpecific ,
+ WithArrows / DispWithArrowsSpecific
+ }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% A sequence of |str| for the options available in |{WithArrows}|. This sequence
+% will be used in the error messages and can be modified dynamically.
+% \begin{macrocode}
+\seq_new:N \l_@@_options_WithArrows_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_WithArrows_seq
+ {
+ adjust, b, c, code-after, code-before, command-name,
+ displaystyle, end-adjust,
+ format, group, groups, i,
+ interline, jot, ll,
+ lr, more-columns, name,
+ no-arrows, rl, rr,
+ show-node-names, show-nodes, start-adjust,
+ t, tikz, tikz-code,
+ xoffset, ygap, ystart
+ }
+\@@_convert_to_str_seq:N \l_@@_options_WithArrows_seq
+% \end{macrocode}
+%
+% \medskip
+% \begin{macrocode}
+\keys_define:nn { WithArrows / WithArrows }
+ {
+ unknown .code:n =
+ \@@_sort_seq:N \l_@@_options_WithArrows_seq
+ \@@_error:n { Unknown~option~WithArrows }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+\keys_define:nn { WithArrows / DispWithArrows }
+ {
+ left-brace .tl_set:N = \l_@@_left_brace_tl ,
+ unknown .code:n =
+ \@@_sort_seq:N \l_@@_options_DispWithArrows_seq
+ \@@_error:n { Unknown~option~DispWithArrows }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% A sequence of the options available in |{DispWithArrows}|. This sequence will
+% be used in the error messages and can be modified dynamically.
+% \begin{macrocode}
+\seq_new:N \l_@@_options_DispWithArrows_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_DispWithArrows_seq
+ {
+ code-after, code-before, command-name, tikz-code, adjust,
+ displaystyle, end-adjust, fleqn, group, format, groups, i, interline, jot,
+ left-brace, ll, lr, mathindent, name, no-arrows, replace-left-brace-by, rl,
+ rr, show-node-names, show-nodes, start-adjust, tikz, wrap-lines, xoffset,
+ ygap, ystart,
+%<*LaTeX>>
+ allow-multiple-labels, tagged-lines, nonumber, notag
+%</LaTeX>
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\keys_define:nn { WithArrows / WithArrowsOptions }
+ {
+ allow-duplicate-names .code:n =
+ \@@_msg_redirect_name:nn { Duplicate~name } { none } ,
+ allow-duplicate-names .value_forbidden:n = true ,
+ unknown .code:n =
+ \@@_sort_seq:N \l_@@_options_WithArrowsOptions_seq
+ \@@_error:n { Unknown~option~WithArrowsOptions }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% A sequence of the options available in |\WithArrowsOptions|. This sequence
+% will be used in the error messages and can be modified dynamically.
+% \begin{macrocode}
+\seq_new:N \l_@@_options_WithArrowsOptions_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_WithArrowsOptions_seq
+ {
+ allow-duplicate-names, b, c, command-name, more-columns, tikz-code, adjust,
+ displaystyle, end-adjust, fleqn, group, groups, i, interline, jot, ll, lr,
+ mathindent, no-arrows, rl, rr, show-node-names, show-nodes, start-adjust, t,
+ tikz, wrap-lines, xoffset, ygap, ystart,
+%<*LaTeX>>
+ allow-multiple-labels, nonumber, notag, standard-behaviour-with-items,
+ tagged-lines
+%</LaTeX>
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_set_independent:| is a command without argument that will be
+% used to specify that the arrow will be ``independent'' (of the potential
+% groups of the option |group| or |groups|). This information will be stored in
+% the field ``status'' of the arrow. Another value of the field ``status'' is
+% ``new-group''.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_set_independent:
+ {
+ \str_if_empty:NTF \l_@@_previous_key_str
+ {
+ \str_set_eq:NN \l_@@_previous_key_str \l_keys_key_tl
+ \str_set:Nn \l_@@_status_arrow_str { independent }
+ \str_if_eq:VnF \l_keys_value_tl { NoValue }
+ { \@@_error:n { Value~for~a~key } }
+ }
+ { \@@_error:n { Incompatible~options~in~Arrow } }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The options of an individual arrow are parsed twice. The first pass is when
+% the command |\Arrow| is read. The second pass is when the arrows are drawn
+% (after the end of the environment |{WithArrows}| or |{DispWithArrows}|). Now,
+% we present the keys set for the first pass. The main goal is to extract
+% informations which will be necessary during the scan of the arrows. For
+% instance, we have to know if some arrows are ``independent'' or use the
+% option ``new-group''.
+% \begin{macrocode}
+\keys_define:nn { WithArrows / Arrow / FirstPass }
+ {
+ jump .code:n =
+ \int_compare:nTF { #1 > 0 }
+ { \int_set:Nn \l_@@_jump_int { #1 } }
+ { \@@_error:n { Negative~jump } } ,
+ jump .value_required:n = true,
+ rr .code:n = \@@_set_independent: ,
+ ll .code:n = \@@_set_independent: ,
+ rl .code:n = \@@_set_independent: ,
+ lr .code:n = \@@_set_independent: ,
+ i .code:n = \@@_set_independent: ,
+ rr .default:n = NoValue ,
+ ll .default:n = NoValue ,
+ rl .default:n = NoValue ,
+ lr .default:n = NoValue ,
+ i .default:n = NoValue ,
+ new-group .value_forbidden:n = true,
+ new-group .code:n =
+ \int_compare:nTF { \l_@@_pos_arrow_int = 6 }
+ { \str_set:Nn \l_@@_status_arrow_str { new-group } }
+ { \@@_error:n { new-group~without~groups } } ,
+% \end{macrocode}
+%
+% \medskip
+% The other keys don't give any information necessary during the scan of the
+% arrows. However, you try to detect errors and that's why all the keys are
+% listed in this keys set. An unknown key will be detected at the point of the
+% command |\Arrow| and not at the end of the environment.
+% \begin{macrocode}
+ tikz-code .code:n = \prg_do_nothing: ,
+ tikz-code .value_required:n = true ,
+ tikz .code:n = \prg_do_nothing: ,
+ tikz .value_required:n = true ,
+% \end{macrocode}
+%
+% \medskip
+% The option |xoffset| is not allowed when the option |group| or the option
+% |groups| is used (since it would be meaningless).
+% \begin{macrocode}
+ xoffset .code:n =
+ \int_compare:nNnT \l_@@_pos_arrow_int > 5
+ { \@@_error:n { Option~xoffset~forbidden } } ,
+ xoffset .value_required:n = true ,
+ start-adjust .code:n = \prg_do_nothing: ,
+ start-adjust .value_required:n = true ,
+ end-adjust .code:n = \prg_do_nothing: ,
+ end-adjust .value_required:n = true ,
+ adjust .code:n = \prg_do_nothing: ,
+ adjust .value_required:n = true ,
+ unknown .code:n =
+ \@@_sort_seq:N \l_@@_options_Arrow_seq
+ \seq_if_in:NVTF \l_@@_options_WithArrows_seq \l_keys_key_tl
+ {
+ \str_set:Nn \l_tmpa_str
+ { ~However,~this~key~can~be~used~in~the~options~of~\{WithArrows\}. }
+ }
+ { \str_clear:N \l_tmpa_str }
+ \@@_error:n { Unknown~option~in~Arrow }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% A sequence of the options available in |\Arrow|. This sequence will be used in
+% the error messages and can be modified dynamically.
+% \begin{macrocode}
+\seq_new:N \l_@@_options_Arrow_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_Arrow_seq
+ {
+ adjust, end-adjust, i, jump, ll, lr, rl, rr, start-adjust, tikz, tikz-code,
+ xoffset
+ }
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_fix_pos_arrow:n #1
+ {
+ \str_if_empty:NT \l_@@_previous_key_str
+ {
+ \str_set_eq:NN \l_@@_previous_key_str \l_keys_key_tl
+ \int_set:Nn \l_@@_pos_arrow_int { #1 }
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The options of the individual commands |\Arrows| are scanned twice. The second
+% pass is just before the drawing of the arrow. In this set of keys, we don't
+% put an item for the unknown keys because an unknown key would have been
+% already detected during the first pass.
+%
+% \begin{macrocode}
+\keys_define:nn {WithArrows / Arrow / SecondPass }
+ {
+ tikz-code .tl_set:N = \l_@@_tikz_code_tl ,
+ tikz-code .initial:n = \draw~(#1)~to~node{#3}~(#2)~; ,
+ tikz .code:n = \tikzset { WithArrows / arrow / .append~style = { #1 } } ,
+ tikz .initial:n = \c_empty_tl ,
+ rr .code:n = \@@_fix_pos_arrow:n 3 ,
+ ll .code:n = \@@_fix_pos_arrow:n 1 ,
+ rl .code:n = \@@_fix_pos_arrow:n 2 ,
+ lr .code:n = \@@_fix_pos_arrow:n 0 ,
+ i .code:n = \@@_fix_pos_arrow:n 5 ,
+% \end{macrocode}
+%
+% \medskip
+% The option |xoffset| is not allowed when the option |group| or the option
+% |groups| is used (since it would be meaningless). An error has been raised
+% during the first pass. Here, we manage to avoid a second error which
+% would be redundant.
+% \begin{macrocode}
+ xoffset .code:n =
+ \int_compare:nNnF \l_@@_pos_arrow_int > 5
+ { \dim_set:Nn \l_@@_xoffset_dim { #1 } } ,
+ start-adjust .dim_set:N = \l_@@_start_adjust_dim,
+ end-adjust .dim_set:N = \l_@@_end_adjust_dim,
+ adjust .code:n =
+ \dim_set:Nn \l_@@_start_adjust_dim { #1 }
+ \dim_set:Nn \l_@@_end_adjust_dim { #1 } ,
+ }
+% \end{macrocode}
+%
+% \bigskip
+% |\WithArrowsOptions| is the command of the \pkg{witharrows} package to fix
+% options at the document level. It's possible to fix in |\WithArrowsOptions|
+% some options specific to |{WithArrows}| (in contrast with |{DispWithArrows}|)
+% or specific to |{DispWithArrows}| (in contrast with |{WithArrows}|). That's
+% why we have constructed a set of keys specific to |\WithArrowsOptions|.
+% \begin{macrocode}
+%<*LaTeX>
+\NewDocumentCommand \WithArrowsOptions { m }
+%</LaTeX>
+%<*plain-TeX>
+\cs_set_protected:Npn \WithArrowsOptions #1
+%</plain-TeX>
+ {
+ \str_clear_new:N \l_@@_previous_key_str
+ \keys_set:nn { WithArrows / WithArrowsOptions } { #1 }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% \subsection{The command \textbackslash Arrow}
+%
+% In fact, the internal command is not named |\Arrow| but |\@@_Arrow|. Usually,
+% at the beginning of an environment |{WithArrows}|, |\Arrow| is set to be
+% equivalent to |\@@_Arrow|. However, the user can change the name with the
+% option |command-name| and the user command for |\@@_Arrow| will be different.
+% This mechanism can be useful when the user has already a command named
+% |\Arrow| he still wants to use in the environments |{WithArrows}| or
+% |{DispWithArrows}|.
+%
+% \medskip
+% \begin{macrocode}
+%<*LaTeX>
+\NewDocumentCommand \@@_Arrow { O { } m ! O { } }
+%</LaTeX>
+%<*plain-TeX>
+\cs_new_protected:Npn \@@_Arrow
+ {
+ \peek_meaning:NTF [
+ { \@@_Arrow_i }
+ { \@@_Arrow_i [ ] }
+ }
+\cs_new_protected:Npn \@@_Arrow_i [ #1 ] #2
+ {
+ \peek_meaning:NTF [
+ { \@@_Arrow_ii [ #1 ] { #2 } }
+ { \@@_Arrow_ii [ #1 ] { #2 } [ ] }
+ }
+\cs_new_protected:Npn \@@_Arrow_ii [ #1 ] #2 [ #3 ]
+%</plain-TeX>
+ {
+% \end{macrocode}
+%
+% The counter |\g_@@_arrow_int| counts the arrows in the environment. The
+% incrementation must be global (|gincr|) because the command |\Arrow| will be
+% used in the cell of a |\halign|. It's recalled that we manage a stack for this
+% counter.
+% \begin{macrocode}
+ \int_gincr:N \g_@@_arrow_int
+% \end{macrocode}
+%
+% \medskip
+% We will construct a global property list to store the informations of the
+% considered arrow. The six fields of this property list are ``initial'',
+% ``final'', ``status'', ``options'', ``label'' and ``input-line''. In order to
+% compute the value of ``final'' (the destination row of the arrow), we have to
+% take into account a potential option |jump|. In order to compute the value of
+% the field ``status'', we have to take into account options as |ll|, |rl|,
+% |rr|, |lr|, etc. or |new-group|.
+%
+% We will do that job with a first analyze of the options of the command
+% |\Arrow| with a dedicated set of keys called |WithArrows/Arrow/FirstPass|.
+%
+% \begin{macrocode}
+ \str_clear_new:N \l_@@_previous_key_str
+ \keys_set:nn { WithArrows / Arrow / FirstPass } { #1 , #3 }
+% \end{macrocode}
+%
+% \medskip
+% We construct now a global property list to store the informations of the
+% considered arrow with the six fields ``initial'', ``final'', ``status'',
+% ``options'', ``label'' and ``input-line''.
+%
+% \smallskip
+% \begin{enumerate}
+% \item First, the row from which the arrow starts:
+% \begin{macrocode}
+ \prop_put:NnV \l_tmpa_prop { initial } \g_@@_line_int
+% \end{macrocode}
+%
+% \item The row where the arrow ends (that's why it was necessary to analyze the
+% key |jump|):
+% \begin{macrocode}
+ \int_set:Nn \l_tmpa_int { \g_@@_line_int + \l_@@_jump_int }
+ \prop_put:NnV \l_tmpa_prop { final } \l_tmpa_int
+% \end{macrocode}
+%
+% \item The ``status'' of the arrow, with 3 possible values: empty,
+% |independent|, or |new-group|.
+% \begin{macrocode}
+ \prop_put:NnV \l_tmpa_prop { status } \l_@@_status_arrow_str
+% \end{macrocode}
+%
+% \item The options of the arrow (it's a token list):
+% \begin{macrocode}
+ \prop_put:Nnn \l_tmpa_prop { options } { #1 , #3 }
+% \end{macrocode}
+%
+% \item The label of the arrow (it's also a token list):
+% \begin{macrocode}
+ \prop_put:Nnn \l_tmpa_prop { label } { #2 }
+% \end{macrocode}
+%
+% \item The number of the line where the command |\Arrow| is issued in the TeX
+% source (as of now, this is only useful for an error message).
+% \begin{macrocode}
+ \prop_put:Nnx \l_tmpa_prop { input-line } \msg_line_number:
+% \end{macrocode}
+% \end{enumerate}
+%
+% The property list has been created in a local variable for convenience. Now,
+% it will be stored in a global variable indicating both the
+% position-in-the-tree and the number of the arrow.
+%
+% \begin{macrocode}
+ \prop_gclear_new:c
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \g_@@_arrow_int _ prop }
+ \prop_gset_eq:cN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \g_@@_arrow_int _ prop }
+ \l_tmpa_prop
+ }
+% \end{macrocode}
+%
+% \medskip
+% The command |\Arrow| (or the corresponding command with a name given by the
+% user with the option |command-name|) will be available only in the last column of
+% the environments |{WithArrows}| and |{DispWithArrows}|. In the other columns,
+% the command will be linked to the following command |\@@_Arrow_first_columns:|
+% which will raise an error.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_Arrow_first_columns:
+ { \@@_error:n { Arrow~not~in~last~column } \@@_Arrow }
+% \end{macrocode}
+%
+%
+% \bigskip
+% \subsection{The environments \{WithArrows\} and \{DispWithArrows\}}
+%
+% \subsubsection{Code before the \textbackslash halign}
+%
+% The command |\@@_pre_halign:n| is a code common to the environments
+% |{WithArrows}| and |{DispWithArrows}|. The argument is the list of options
+% given to the environment.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_pre_halign:n #1
+% \end{macrocode}
+%
+% First, the initialisation of |\l_@@_type_env_str| which is the name of the
+% encompassing environment. In fact, this token list is used only in the error
+% messages.
+% \begin{macrocode}
+ {
+%<*LaTeX>
+ \str_clear_new:N \l_@@_type_env_str
+ \str_set:NV \l_@@_type_env_str \@currenvir
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% We deactivate the potential externalization of Tikz. The Tikz elements created
+% by \pkg{witharrows} can't be externalized since they are created in Tikz
+% pictures with |overlay| and |remember picture|.
+% \begin{macrocode}
+ \cs_if_exist:NT \tikz@library@external@loaded
+ { \tikzset { external / export = false } }
+% \end{macrocode}
+%
+% \bigskip
+% The token list |\l_@@_name_str| will contain the potential name of the
+% environment (given with the option |name|). This name will be used to create
+% aliases for the names of the nodes.
+% \begin{macrocode}
+ \str_clear_new:N \l_@@_name_str
+% \end{macrocode}
+%
+% \bigskip
+% The parameter |\l_@@_status_arrow_str| will be used to store the ``status'' of
+% an individual arrow. It will be used to fill the field ``status'' in the
+% property list describing an arrow.
+% \begin{macrocode}
+ \str_clear_new:N \l_@@_status_arrow_str
+% \end{macrocode}
+%
+% \bigskip
+% The dimension |\l_@@_x_dim| will be used to compute the $x$-value for some
+% vertical arrows when one of the options |i|, |group| and |groups| (values 5, 6
+% and 7 of |\l_@@_pos_arrow_int|) is used.
+% \begin{macrocode}
+ \dim_zero_new:N \l_@@_x_dim
+% \end{macrocode}
+%
+% \medskip
+% The variable |\l_@@_input_line_str| will be used only to store, for each
+% command |\Arrow| the line (in the TeX file) where the command is issued. This
+% information will be stored in the field ``input-line'' of the arrow. As of
+% now, this information is used only in the error message of a arrow impossible
+% to draw (because it arrives after the last row of the environment).
+% \begin{macrocode}
+ \str_clear_new:N \l_@@_input_line_str
+% \end{macrocode}
+%
+%
+% The initialisation of the counters |\g_@@_arrow_int|, |\g_@@_line_int| and
+% |\g_@@_col_int|. However, we have to save their previous values with the
+% stacks created for this end.
+% \begin{macrocode}
+ \seq_gput_right:NV \g_@@_arrow_int_seq \g_@@_arrow_int
+ \int_gzero:N \g_@@_arrow_int
+ \seq_gput_right:NV \g_@@_line_int_seq \g_@@_line_int
+ \int_gzero:N \g_@@_line_int
+ \seq_gput_right:NV \g_@@_col_int_seq \g_@@_col_int
+ \int_gzero:N \g_@@_col_int
+% \end{macrocode}
+%
+% In the preamble of the |\halign|, there will be \emph{two} counters of the
+% columns. The aim of this programmation is to detect the utilisation of a
+% command |\omit| in a cell of the |\halign| (it should be forbidden).
+% For example, in the part of the preamble concerning the third column (if there
+% is a third column in the environment), we will have the following instructions :
+% \begin{Verbatim}
+% \int_gincr:N \g_~@~@_col_int
+% \int_gset:Nn \g_~@~@_static_col_int 3
+% \end{Verbatim}
+% The counter |\g_@@_col_int| is incremented dynamically and the second is
+% static. If the user has used a command |\omit|, the dynamic incrementation is
+% not done in the cell and, at this end of the row, the difference between the
+% counters may infer the presence of |\omit| at least once.
+% \begin{macrocode}
+ \int_gzero_new:N \g_@@_static_col_int
+% \end{macrocode}
+%
+% \bigskip
+% We also have to update the position on the nesting tree.
+% \begin{macrocode}
+ \seq_gput_right:Nn \g_@@_position_in_the_tree_seq 1
+% \end{macrocode}
+%
+% The nesting tree is used to create a prefix which will be used in the names of
+% the Tikz nodes and in the names of the arrows (each arrow is a property list
+% of six fields). If we are in the second environment |{WithArrows}| nested in
+% the third environment |{WithArrows}| of the document, the prefix will be |3-2|
+% (although the position in the tree is $[3,2,1]$ since such a position always
+% ends with a~$1$). First, we do a copy of the position-in-the-tree and then we
+% pop the last element of this copy (in order to drop the last~$1$).
+% \begin{macrocode}
+ \seq_set_eq:NN \l_tmpa_seq \g_@@_position_in_the_tree_seq
+ \seq_pop_right:NN \l_tmpa_seq \l_tmpa_tl
+ \str_clear_new:N \l_@@_prefix_str
+ \str_set:Nx \l_@@_prefix_str { \seq_use:Nnnn \l_tmpa_seq - - - }
+% \end{macrocode}
+%
+% \bigskip
+% We define the command |\\| to be the command |\@@_cr:| (defined below).
+% \begin{macrocode}
+ \cs_set_eq:NN \\ \@@_cr:
+ \dim_zero:N \mathsurround
+% \end{macrocode}
+%
+% \bigskip
+% These counters will be used later as variables.
+% \begin{macrocode}
+ \int_zero_new:N \l_@@_initial_int
+ \int_zero_new:N \l_@@_final_int
+ \int_zero_new:N \l_@@_arrow_int
+ \int_zero_new:N \l_@@_pos_of_arrow_int
+ \int_zero_new:N \l_@@_jump_int
+% \end{macrocode}
+%
+% \medskip
+% The counter |\l_@@_jump_int| corresponds to the option |jump|. Now, we set the
+% default value for this option.
+% \begin{macrocode}
+ \int_set:Nn \l_@@_jump_int \c_one_int
+% \end{macrocode}
+%
+% \medskip
+% The string |\l_@@_format_str| corresponds to the option |format|. Now, we set
+% the default value for this option.
+% \begin{macrocode}
+ \str_set:Nn \l_@@_format_str { rl }
+% \end{macrocode}
+%
+%
+%
+% \bigskip
+% In (the last column of) |{DispWithArrows}|, it's possible to put several
+% labels (for the same number of equation). That's why these labels will be
+% stored in a sequence |\l_@@_labels_seq|.
+% \begin{macrocode}
+%<*LaTeX>
+ \seq_clear_new:N \l_@@_labels_seq
+% \end{macrocode}
+%
+% \begin{macrocode}
+ \bool_set_false:N \l_@@_tag_next_line_bool
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% The value corresponding to the key |interline| is put to zero before the
+% treatment of the options of the environment.\footnote{It's recalled that, by
+% design, the option |interline| of an environment doesn't apply in the nested
+% environments.}
+% \begin{macrocode}
+ \skip_zero:N \l_@@_interline_skip
+% \end{macrocode}
+%
+% \bigskip
+% The value corresponding to the key |code-before| is put to nil before the
+% treatment of the options of the environment, because, of course, we don't want
+% the code executed at the beginning of all the nested
+% environments~|{WithArrows}|. Idem for |code-after|.
+% \begin{macrocode}
+ \tl_clear_new:N \l_@@_code_before_tl
+ \tl_clear_new:N \l_@@_code_after_tl
+% \end{macrocode}
+%
+% \bigskip
+% We process the options given to the environment |{WithArrows}| or
+% |{DispWithArrows}|.
+% \begin{macrocode}
+ \str_clear_new:N \l_@@_previous_key_str
+ \bool_if:NT \l_@@_in_WithArrows_bool
+ { \keys_set:nn { WithArrows / WithArrows } { #1 } }
+ \bool_if:NT \l_@@_in_DispWithArrows_bool
+ { \keys_set:nn { WithArrows / DispWithArrows } { #1 } }
+% \end{macrocode}
+%
+% \medskip
+% Now we link the command |\Arrow| (or the corresponding command with a name
+% given by the user with the option |command-name|: that's why the following line
+% must be after the loading of the options) to the command
+% |\@@_Arrow_first_columns:| which will raise an error.
+% \begin{macrocode}
+ \cs_set_eq:cN \l_@@_command_name_str \@@_Arrow_first_columns:
+% \end{macrocode}
+% It's only in the last column of the environment that it will be linked to the
+% command |\@@_Arrow:|.
+%
+% \medskip
+% The counter |\l_@@_nb_cols_int| is the number of columns in the
+% |\halign| (excepted the column for the labels of equations in
+% |{DispWithArrows}| and excepted eventuals other columns in |{WithArrows}| allowed
+% by the option |more-columns|).
+% \begin{macrocode}
+ \int_set:Nn \l_@@_nb_cols_int { \str_count:N \l_@@_format_str }
+% \end{macrocode}
+%
+% \medskip
+% Be careful! The following counter |\g_@@_col_int| will be used for two usages:
+% \begin{itemize}
+% \item during, the construction of the preamble of the |\halign|, it will be
+% used as counter for the number of the column under construction in the
+% preamble (since the preamble is constructed backwards, |\g_@@_col_int| will go
+% decreasing from |\l_@@_nb_cols_int| to $1$) ;
+% \item once the preamble constructed, the primitive |\halign| is executed, and,
+% in each row of the |\halign|, the counter |\g_@@_col_int| will be increased
+% from column to column.
+% \end{itemize}
+%
+% \begin{macrocode}
+ \int_gset_eq:NN \g_@@_col_int \l_@@_nb_cols_int
+% \end{macrocode}
+%
+% \medskip
+% We convert the format in a sequence because we use it as a stack (with the top
+% of the stack at the end of the sequence) in the construction of the preamble.
+% \begin{macrocode}
+ \seq_clear_new:N \l_@@_format_seq
+ \seq_set_split:NnV \l_@@_format_seq { } \l_@@_format_str
+% \end{macrocode}
+%
+% \bigskip
+% If the option |footnote| or the option |footnotehyper| is used, then we
+% extract the footnotes with an environment |{savenotes}| (of the package
+% \pkg{footnote} or the package \pkg{footnotehyper}).
+% \begin{macrocode}
+%<*LaTeX>
+ \bool_if:NT \g_@@_footnote_bool { \begin { savenotes } }
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% We execute the code |\l_@@_code_before_tl| of the option |code-before| of the
+% environment after the eventual |\begin{savenotes}| and, symetrically, we will
+% execute the |\l_@@_code_after_tl| before the eventual |\end{savenotes}| (we
+% have a good reason for the last point: we want to extract the footnotes of the
+% arrows executed in the |code-after|).
+% \begin{macrocode}
+ \l_@@_code_before_tl
+% \end{macrocode}
+%
+% \bigskip
+% The command |\spread@equation| is the command used by \pkg{amsmath} in the
+% beginning of an alignment to fix the interline. When used, it becomes no-op.
+% However, it's possible to use \pkg{witharrows} without \pkg{amsmath} since we
+% have redefined |\spread@equation| (if it is not defined yet).
+% \begin{macrocode}
+ \spread@equation
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+%<*LaTeX>
+ \cs_set_eq:NN \notag \@@_notag:
+ \cs_set_eq:NN \nonumber \@@_nonumber:
+ \cs_set_eq:NN \tag \@@_tag
+ \cs_set_eq:NN \@@_old_label \label
+ \cs_set_eq:NN \label \@@_label:n
+ \cs_set_eq:NN \tagnextline \@@_tagnextline:
+%</LaTeX>
+ }
+% \end{macrocode}
+% This is the end of |\@@_pre_halign:n|.
+%
+% \bigskip
+% \subsubsection{The construction of the preamble of the \textbackslash halign}
+%
+% The control sequence |\@@_construct_halign:| will ``start'' the |\halign| and
+% the preamble. In fact, it constructs all the preamble excepted the end of
+% the last column (more precisely: except the part concerning the construction
+% of the left node and the right node).
+%
+% The same function |\@@_construct_halign:| will be used both for the
+% environment |{WithArrows}| and the environment |{DispWithArrows}|.
+%
+% Several important points must be noted concerning that construction of the
+% preamble.
+% \begin{itemize}
+% \item The construction of the preamble is done by reading backwards the
+% format |\l_@@_format_str| and adding the corresponding tokens in the input
+% stream of TeX. That means that the part of the preamble concerning the last
+% cell will be constructed first.
+% \item The function |\@@_construct_halign:| is recursive in order to treat
+% succesively all the letters of the preamble.
+% \item Each part of the preamble is created with a |\use:x| function. This
+% expansion of the preamble gives the ability of controlling which parts of the
+% code will be expanded during the construction of the preamble (other parts
+% will be expanded and executed only during the execution of the |\halign|).
+% \item The counter |\g_@@_col_int| is used during the loop of the construction
+% of the preamble but, it will also appears in the preamble (we could have
+% chosen two differents counters but this way saves a counter).
+% \end{itemize}
+%
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_construct_halign:
+ {
+ \seq_pop_right:NNTF \l_@@_format_seq \l_@@_type_col_str
+ {
+% \end{macrocode}
+% Here is the |\use:x| which is fundamental: it will really construct the part
+% of the preamble corresponding to a column by expanding only some parts of the
+% following code.
+% \begin{macrocode}
+ \use:x
+ {
+% \end{macrocode}
+% Before the recursive call of |\@@_construct_halign:|, we decrease the integer
+% |\g_@@_col_bool|. But, during the construction of the column which is
+% constructed first (that is to say which is the last column of the |\halign|),
+% it is \emph{not} lowered because |\int_decr:N|, which is protected, won't be
+% expanded by the |\use:x|.
+%
+% We begin the construction of a generic column.
+% \begin{macrocode}
+ \int_gdecr:N \g_@@_col_int
+ \@@_construct_halign:
+ \int_compare:nNnT \g_@@_col_int = \l_@@_nb_cols_int
+ {
+% \end{macrocode}
+% We redefine the command |\Arrow| (or the name given to the corresponding
+% command by the option |command-name|) in each cell of the last column.
+% The braces around |\l_@@_command_name_str| are mandatory because
+% |\l_@@_command_name_str| will be expanded by the |\use:x| and the command
+% |\cs_set_eq:cN| must still be efficient during the execution of the |\halign|.
+% \begin{macrocode}
+ \cs_set_eq:cN { \l_@@_command_name_str } \@@_Arrow
+%<*LaTeX>
+ \bool_if:NT \l_@@_in_DispWithArrows_bool
+ {
+% \end{macrocode}
+% The command |\@@_test_if_to_tag:| (which is protected and, thus, will not be
+% expanded during the construction of the preamble) will test, at each row,
+% whether the current row must be tagged (and the tag will be put in the very
+% last column).
+% \begin{macrocode}
+ \@@_test_if_to_tag:
+% \end{macrocode}
+% The command |\@@_set_qedhere:| will do a redefinition of |\qedhere| in each
+% cell of the last column.
+% \begin{macrocode}
+ \bool_if:NT \c_@@_amsthm_loaded_bool \@@_set_qedhere:
+ }
+%</LaTeX>
+ }
+ \str_if_eq:VnT \l_@@_type_col_str { c } \hfil
+ \str_if_eq:VnT \l_@@_type_col_str { r } \hfill
+ \int_gincr:N \g_@@_col_int
+ \int_gset:Nn \g_@@_static_col_int { \int_use:N \g_@@_col_int }
+ \c_math_toggle_token
+ {
+ { }
+ \bool_if:NT \l_@@_displaystyle_bool \displaystyle
+ ####
+ }
+ \c_math_toggle_token
+ \int_compare:nNnTF \g_@@_col_int = \l_@@_nb_cols_int
+ { \@@_construct_nodes: }
+ {
+% \end{macrocode}
+% The following glue (|\hfil|) will be added only if we are not in the last cell
+% because, in the last cell, a glue (=skip) is added between the nodes (in
+% |\@@_construct_nodes:|).
+% \begin{macrocode}
+ \str_if_eq:VnT \l_@@_type_col_str { l } \hfil
+ \str_if_eq:VnT \l_@@_type_col_str { c } \hfil
+ \bool_if:NT \l_@@_in_DispWithArrows_bool { \tabskip = \c_zero_skip }
+ &
+ }
+ }
+ }
+% \end{macrocode}
+% Now the tokens that will be inserted after the analyze of all the tokens of
+% the format: here is the token |\halign|.
+% \begin{macrocode}
+ {
+ \bool_if:NTF \l_@@_in_WithArrows_bool
+ {
+ \ialign
+ \bgroup
+ }
+ {
+ \halign to \l_@@_linewidth_dim
+ \bgroup
+ \bool_if:NT \l_@@_fleqn_bool
+ { \skip_horizontal:N \l_@@_mathindent_dim }
+ }
+ \int_gincr:N \g_@@_line_int
+ \int_gzero:N \g_@@_col_int
+ \tl_if_eq:NNF \l_@@_left_brace_tl \c_novalue_tl
+ {
+ \skip_horizontal:n
+ { \box_wd:N \l_@@_left_brace_box + \l_@@_delim_wd_dim }
+ }
+ \strut
+ }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% The command |\@@_construct_nodes:| is only for the lisibility of the code
+% because, in fact, it is used only once. It constructs the ``left node'' and
+% the ``right node'' at the end of each row of the arrow.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_construct_nodes:
+ {
+% \end{macrocode}
+% We create the ``left node'' of the line (when using macros in Tikz node names,
+% the macros have to be fully expandable: here, |\int_use:N| is fully
+% expandable).
+% \begin{macrocode}
+ \tikz [ remember~picture , overlay ]
+ \node
+ [
+ node~contents = { } ,
+ @@_node_style ,
+ name = wa - \l_@@_prefix_str - \int_use:N \g_@@_line_int - l ,
+ alias =
+ {
+ \str_if_empty:NF \l_@@_name_str
+ { \l_@@_name_str - \int_use:N \g_@@_line_int - l }
+ }
+ ]
+ ;
+ \hfil
+% \end{macrocode}
+%
+% \bigskip
+% Now, after the |\hfil|, we create the ``right node'' and, if the option
+% |show-node-names| is raised, the name of the node is written in the document
+% (useful for debugging).
+% \begin{macrocode}
+ \tikz [ remember~picture , overlay ]
+ \node
+ [
+ node~contents = { } ,
+ @@_node_style ,
+ name = wa - \l_@@_prefix_str - \int_use:N \g_@@_line_int - r ,
+ alias =
+ {
+ \str_if_empty:NF \l_@@_name_str
+ { \l_@@_name_str - \int_use:N \g_@@_line_int - r }
+ }
+ ]
+ ;
+ \bool_if:NT \l_@@_show_node_names_bool
+ {
+ \hbox_overlap_right:n
+ { \small wa - \l_@@_prefix_str - \int_use:N \g_@@_line_int - r }
+ }
+ }
+% \end{macrocode}
+%
+%
+%
+% \bigskip
+% \subsubsection{The environment \{WithArrows\}}
+%
+%
+% \begin{macrocode}
+%<*LaTeX>
+\NewDocumentEnvironment { WithArrows } { ! O { } }
+%</LaTeX>
+%<*plain-TeX>
+\cs_new_protected:Npn \WithArrows
+ {
+ \group_begin:
+ \peek_meaning:NTF [
+ { \WithArrows_i }
+ { \WithArrows_i [ ] }
+ }
+\cs_new_protected:Npn \WithArrows_i [ #1 ]
+%</plain-TeX>
+ {
+ \bool_set_true:N \l_@@_in_WithArrows_bool
+ \bool_set_false:N \l_@@_in_DispWithArrows_bool
+%<*plain-TeX>
+ \str_clear_new:N \l_@@_type_env_str
+ \str_set:Nn \l_@@_type_env_str { WithArrows }
+%</plain-TeX>
+ \@@_pre_halign:n { #1 }
+ \if_mode_math: \else:
+ \@@_error:n { WithArrows~outside~math~mode }
+ \fi:
+% \end{macrocode}
+%
+% \bigskip
+% The environment begins with a |\vtop|, a |\vcenter| or a
+% |\vbox|\footnote{Notice that the use of |\vtop| seems color-safe here...}
+% depending of the value of |\l_@@_pos_env_int| (fixed by the options |t|, |c|
+% or |b|). The environment |{WithArrows}| must be used in math mode\footnote{An
+% error is raised if the environment is used outside math mode.} and therefore,
+% we can use |\vcenter|.
+% \begin{macrocode}
+ \int_case:nn \l_@@_pos_env_int { 0 \vtop 1 \vcenter 2 \vbox }
+ \bgroup
+% \end{macrocode}
+%
+% \bigskip
+% We begin the |\halign| and the preamble. During the construction of the
+% preamble, |\l_tmpa_int| will be incremented during each column constructed.
+% \begin{macrocode}
+ \@@_construct_halign:
+% \end{macrocode}
+%
+%
+% \medskip
+% In fact, the construction of the preamble is not finished. We add a little more.
+%
+% \medskip
+% An environmemnt |{WithArrows}| should have a number of columns equal to the
+% length of its format (by default, 2 since the default format is |rl|).
+% Nevertheless, if the user wants to use more columns (without arrows)
+% it's possible with the option |more-columns|.
+% \begin{macrocode}
+ &&
+ \@@_error:n { Too~much~columns~in~WithArrows }
+ \c_math_toggle_token
+ \bool_if:NT \l_@@_displaystyle_bool \displaystyle
+ { ## }
+ \c_math_toggle_token
+ \cr
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% We begin the second part of the environment |{WithArrows}|. We have two
+% |\egroup|\,: one for the |\halign| and one for the |\vtop| (or |\vcenter| or
+% |\vbox|).
+% \begin{macrocode}
+%<*plain-TeX>
+\cs_new_protected:Npn \endWithArrows
+%</plain-TeX>
+ {
+ \\
+ \egroup
+ \egroup
+ \@@_post_halign:
+% \end{macrocode}
+%
+% \bigskip
+% If the option |footnote| or the option |footnotehyper| is used, then we
+% extract the footnotes with an environment |{footnote}| (of the package
+% \pkg{footnote} or the package \pkg{footnotehyper}).
+% \begin{macrocode}
+%<*LaTeX>
+ \bool_if:NT \g_@@_footnote_bool { \end { savenotes } }
+%</LaTeX>
+%<*plain-TeX>
+ \group_end:
+%</plain-TeX>
+ }
+% \end{macrocode}
+% This is the end of the environment |{WithArrows}|.
+%
+%
+% \bigskip
+% \subsubsection{After the construction of the \textbackslash halign}
+%
+% The command |\@@_post_halign:| is a code common to the second part of the
+% environment |{WithArrows}| and the environment |{DispWithArrows}|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_post_halign:
+% \end{macrocode}
+%
+% \bigskip
+% The command |\WithArrowsRightX| is not used by \pkg{witharrows}. It's only a
+% convenience given to the user.
+% \begin{macrocode}
+ {
+ \cs_set:Npn \WithArrowsRightX { \g_@@_right_x_dim }
+% \end{macrocode}
+%
+% \bigskip
+% It there is really arrows in the environment, we draw the arrows.
+% \begin{macrocode}
+ \int_compare:nNnT \g_@@_arrow_int > 0 \@@_scan_arrows:
+% \end{macrocode}
+%
+% \bigskip
+% We will execute the code specified in the option |code-after|, after some
+% settings.
+% \begin{macrocode}
+ \group_begin:
+ \tikzset { every~picture / .style = @@_standard }
+% \end{macrocode}
+% The command |\WithArrowsNbLines| is not used by \pkg{witharrows}. It's only a
+% convenience given to the user.
+% \begin{macrocode}
+ \cs_set:Npn \WithArrowsNbLines { \int_use:N \g_@@_line_int }
+% \end{macrocode}
+% The command |\MultiArrow| is available in |code-after|, and we have a special
+% version of |\Arrow|, called ``|\Arrow| in |code-after|'' in the
+% documentation.\footnote{As for now, |\MultiArrow| has no option, and that's
+% why its internal name is a name of \pkg{expl3} with the signature |:nn|
+% whereas |\Arrow| in |code-after| provides options and has the name of a
+% function defined with |\NewDocumentCommand|.}
+% \begin{macrocode}
+ \cs_set_eq:NN \MultiArrow \@@_MultiArrow:nn
+ \cs_set_eq:cN \l_@@_command_name_str \@@_Arrow_code_after
+ \bool_set_true:N \l_@@_in_code_after_bool
+ \l_@@_code_after_tl
+ \group_end:
+% \end{macrocode}
+%
+% \bigskip
+% We update the position-in-the-tree. First, we drop the last component and then
+% we increment the last element.
+% \begin{macrocode}
+ \seq_gpop_right:NN \g_@@_position_in_the_tree_seq \l_tmpa_tl
+ \seq_gpop_right:NN \g_@@_position_in_the_tree_seq \l_tmpa_tl
+ \seq_gput_right:Nx \g_@@_position_in_the_tree_seq
+ { \int_eval:n { \l_tmpa_tl + 1 } }
+% \end{macrocode}
+%
+% \bigskip
+% We update the value of the counter |\g_@@_last_env_int|. This counter is used
+% only by the user function |\WithArrowsLastEnv|.
+% \begin{macrocode}
+ \int_compare:nNnT { \seq_count:N \g_@@_position_in_the_tree_seq } = 1
+ { \int_gincr:N \g_@@_last_env_int }
+% \end{macrocode}
+%
+% \bigskip
+% Finally, we restore the previous values of the counters |\g_@@_arrow_int|,
+% |\g_@@_line_int| and |\g_@@_col_int|. It is recalled that we manage three
+% stacks in order to be able to do such a restoration.
+% \begin{macrocode}
+ \seq_gpop_right:NN \g_@@_arrow_int_seq \l_tmpa_tl
+ \int_gset:Nn \g_@@_arrow_int \l_tmpa_tl
+ \seq_gpop_right:NN \g_@@_line_int_seq \l_tmpa_tl
+ \int_gset:Nn \g_@@_line_int \l_tmpa_tl
+ \seq_gpop_right:NN \g_@@_col_int_seq \l_tmpa_tl
+ \int_gset:Nn \g_@@_col_int \l_tmpa_tl
+ }
+% \end{macrocode}
+% That's the end of the command |\@@_post_halign:|.
+%
+% \bigskip
+% \subsubsection{The command of end of row}
+%
+% We give now the definition of |\@@_cr:| which is the definition of |\\| in an
+% environment |{WithArrows}|. The two \pkg{expl3} commands
+% |\group_align_safe_begin:| and |\group_align_safe_end:| are specifically
+% designed for this purpose: test the token that follows in an |\halign|
+% structure.
+%
+% First, we remove an eventual token |*| (just after the |\\|: there should not
+% be space between the two) since the commands |\\| and |\\*| are equivalent in
+% an environment |{WithArrows}| (an environment |{WithArrows}|, like an
+% environment |{aligned}| of \pkg{amsmath}, is always unbreakable).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_cr:
+ {
+ \scan_stop:
+% \end{macrocode}
+% We try to detect some |\omit| (as of now, an |\omit| in the last column is
+% not detected).
+% \begin{macrocode}
+ \int_compare:nNnF \g_@@_col_int = \g_@@_static_col_int
+ { \@@_error:n { omit~probably~used } }
+ \prg_replicate:nn { \l_@@_nb_cols_int - \g_@@_static_col_int } { & { } }
+ \group_align_safe_begin:
+ \peek_meaning_remove:NTF * \@@_cr_i: \@@_cr_i:
+ }
+% \end{macrocode}
+%
+% \medskip
+% Then, we peek the next token to see if it's a |[|. In this case, the command
+% |\\| has an optional argument which is the vertical skip (=glue) to put.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_cr_i:
+ { \peek_meaning:NTF [ \@@_cr_ii: { \@@_cr_ii: [ \c_zero_dim ] } }
+% \end{macrocode}
+%
+% \bigskip
+% Now, we test if the next token is the token |\end|. Indeed, we want to test if
+% the following tokens are |\end{WithArrows}| (or |\end{DispWithArrows}|, etc).
+% In this case, we raise an error because the user must not put "\\" at the end
+% of its alignment.
+% \begin{macrocode}
+%<*LaTeX>
+\cs_new_protected:Npn \@@_cr_ii: [ #1 ]
+ {
+ \peek_meaning_ignore_spaces:NTF \end
+ {
+ \@@_cr_iii:n { #1 }
+% \end{macrocode}
+% The analyse of the argument of the token |\end| must be after the
+% |\group_align_safe_end:| which is the beginning of |\@@_cr_iii:n|.
+% \begin{macrocode}
+ \@@_analyze_end:Nn
+ }
+ { \@@_cr_iii:n { #1 } }
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_cr_iii:n #1
+%</LaTeX>
+%<*plain-TeX>
+\cs_new_protected:Npn \@@_cr_ii: [ #1 ]
+%</plain-TeX>
+ {
+ \group_align_safe_end:
+% \end{macrocode}
+% For the environment |{DispWithArrows}|, the behaviour of |\\| is different
+% because we add the last column which is the column for the tag (number of the
+% equation). Even if there is no tag, this column is used for the
+% |v|-nodes.\footnote{The |v|-nodes are used to compute the abscissa of the
+% right margin, used by the option |wrap-lines|.}
+% \begin{macrocode}
+ \bool_if:NT \l_@@_in_DispWithArrows_bool
+% \end{macrocode}
+% At this stage, we know that we have a tag to put if (and only if) the value of
+% |\l_@@_tags_clist| is the comma list |all| (only one element). Maybe,
+% previously, the value of |\l_@@_tags_clist| was, for example, |1,last| (which
+% means that only the first line and the last line must be tagged). However, in
+% this case, the comparison with the number of line has be done before and, now,
+% if we are in a line to tag, the value of |\l_@@_tags_clist| is |all|.
+% \begin{macrocode}
+ {
+%<*LaTeX>
+ \clist_if_in:NnTF \l_@@_tags_clist { all }
+ {
+% \end{macrocode}
+% Here, we can't use |\refstepcounter{equation}| because if the user has issued
+% a |\tag| command, we have to use |\l_@@_tag_tl| and not |\theequation|. That's
+% why we have to do the job done by |\refstepcounter| manually.
+%
+% First, the incrementation of the counter (potentially).
+% \begin{macrocode}
+ \tl_if_empty:NT \l_@@_tag_tl { \int_gincr:N \c@equation }
+% \end{macrocode}
+%
+% We store in |\g_tmpa_tl| the tag we will have to compose at the end of the
+% line. We use a global variable because we will use it in the \emph{next} cell
+% (after the |&|).
+% \begin{macrocode}
+ \cs_gset:Npx \g_tmpa_tl
+ { \tl_if_empty:NTF \l_@@_tag_tl \theequation \l_@@_tag_tl }
+% \end{macrocode}
+% It's possible to put several labels for the same line (it's not possible in
+% the environments of \pkg{amsmath}). That's why the differents labels of a same
+% line are stored in a sequence |\l_@@_labels_seq|.
+% \begin{macrocode}
+ \seq_if_empty:NF \l_@@_labels_seq
+ {
+% \end{macrocode}
+% Now, we do the job done by |\refstepcounter| and by the redefinitions of
+% |\refstepcounter| done by some packages (the incrementation of the counter has
+% been done yet).
+%
+% First an action which is in the definition of |\refstepcounter|. The command
+% |\p@equation| is redefined by some extensions like \pkg{fncylab}.
+% \begin{macrocode}
+ \cs_set:Npx \@currentlabel { \p@equation \g_tmpa_tl }
+% \end{macrocode}
+% Then, an action done by \pkg{hyperref} in its redefinition of
+% |\refstepcounter|.
+% \begin{macrocode}
+ \bool_if:NT \c_@@_hyperref_loaded_bool
+ {
+ \str_set:Nn \This@name { equation }
+ \hyper@refstepcounter { equation }
+ }
+% \end{macrocode}
+% Then, an action done by \pkg{cleveref} in its redefinition of
+% |\refstepcounter|. The package \pkg{cleveref} creates in the |aux| file a
+% command |\cref@currentlabel| similar to |\@currentlabel| but with more
+% informations.
+% \begin{macrocode}
+ \bool_if:NT \c_@@_cleveref_loaded_bool
+ {
+ \cref@constructprefix { equation } \cref@result
+ \protected@edef \cref@currentlabel
+ {
+ [
+ \cs_if_exist:NTF \cref@equation@alias
+ \cref@equation@alias
+ { equation }
+ ]
+ [ \arabic { equation } ] [ \cref@result ]
+ \p@equation \g_tmpa_tl
+ }
+ }
+% \end{macrocode}
+% Now, we can issue the command |\label| (some packages may have redefined
+% |\label|, for example \pkg{typedref}) for each item in the sequence of the
+% labels (it's possible with \pkg{witharrows} to put several labels to the same
+% line and that's why the labels are in the sequence |\l_@@_labels_seq|).
+% \begin{macrocode}
+ \seq_map_function:NN \l_@@_labels_seq \@@_old_label
+ }
+% \end{macrocode}
+% We save the booleans |\l_@@_tag_star_bool| and |\l_@@_qedhere_bool| because
+% they will be used in the \emph{next} cell (after the |&|). We recall that the
+% cells of a |\halign| are TeX groups.
+% \begin{macrocode}
+ \@@_save:N \l_@@_tag_star_bool
+ \@@_save:N \l_@@_qedhere_bool
+ \bool_if:NT \l_@@_tag_next_line_bool
+ {
+ \openup -\jot
+ \bool_set_false:N \l_@@_tag_next_line_bool
+ \notag \\ &
+ }
+ &
+ \@@_restore:N \l_@@_tag_star_bool
+ \@@_restore:N \l_@@_qedhere_bool
+ \bool_if:NT \l_@@_qedhere_bool
+ { \hbox_overlap_left:n \@@_qedhere_i: }
+ \cs_set_eq:NN \theequation \g_tmpa_tl
+ \bool_if:NT \l_@@_tag_star_bool
+ { \cs_set_eq:NN \tagform@ \prg_do_nothing: }
+% \end{macrocode}
+% We use |\@eqnnum| (we recall that there are two definitions of |\@eqnnum|, a
+% standard definition and another, loaded if the class option |leqno| is used).
+% However, of course, the position of the |v|-node is not the same whether the
+% option |leqno| is used or not. That's here that we use the flag
+% |\c_@@_leqno_bool|.
+% \begin{macrocode}
+ \hbox_overlap_left:n
+ {
+ \bool_if:NF \c_@@_leqno_bool
+ {
+ \tikz [ @@_standard ]
+ \coordinate ( \int_use:N \g_@@_line_int - v ) ;
+ }
+ \quad
+ \@eqnnum
+ }
+ \bool_if:NT \c_@@_leqno_bool
+ {
+ \tikz [ @@_standard ]
+ \coordinate ( \int_use:N \g_@@_line_int - v ) ;
+ }
+ }
+ {
+ \@@_save:N \l_@@_qedhere_bool
+%</LaTeX>
+ &
+%<*LaTeX>
+ \@@_restore:N \l_@@_qedhere_bool
+ \bool_if:NT \l_@@_qedhere_bool
+ { \hbox_overlap_left:n \@@_qedhere_i: }
+%</LaTeX>
+ \tikz [ @@_standard ]
+ \coordinate ( \int_use:N \g_@@_line_int - v ) ;
+%<*LaTeX>
+ }
+%</LaTeX>
+ }
+ \dim_compare:nNnT { #1 } < \c_zero_dim
+ { \@@_error:n { option~of~cr~negative } }
+
+ \cr
+ \noalign
+ {
+ \dim_set:Nn \l_tmpa_dim { \dim_max:nn { #1 } \c_zero_dim }
+ \skip_vertical:n { \l_tmpa_dim + \l_@@_interline_skip }
+ \scan_stop:
+ }
+ }
+% \end{macrocode}
+% According to the documentation of \pkg{expl3}, the previous addition in
+% ``|#1 + \l_@@_interline_skip|'' is really an addition of skips (=glues).
+%
+%
+% The following command will be used when, after a |\\| (and its optional
+% arguments) there is a |\end|. You want to known if this is the end of the
+% environment |{WithArrows}| (or |{DispWithArrows}|, etc.) because, in this
+% case, we will explain that the environment must not be ended by |\\|. If it is
+% not the case, that means it's a classical situation of LaTeX environments not
+% correctly imbricated and there will be a LaTeX error.
+% \begin{macrocode}
+%<*LaTeX>
+\cs_new_protected:Npn \@@_analyze_end:Nn #1 #2
+ {
+ \exp_args:NV \str_if_eq:nnT \l_@@_type_env_str { #2 }
+ { \@@_warning:n { newline~at~the~end~of~env } }
+% \end{macrocode}
+% We reput in the stream the |\end{...}| we have extracted.
+% \begin{macrocode}
+ \end { #2 }
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+% \bigskip
+% \subsubsection{The environment \{DispWithArrows\}}
+%
+% For the environment |{DispWithArrows}|, the general form of the construction
+% is of the type:
+%
+% |\[\vtop{\halign to \displaywidth {...}}\]|
+%
+% The purpose of the |\vtop| is to have an environment unbreakable.
+%
+% However, if we are juste after an item of a LaTeX list or at the beginning of
+% a |{minipage}|, the construction is slightly different:
+%
+% |\[\vtop{\halign to \linewidth {...}}\]|
+%
+%
+% \bigskip
+% The boolean |\l_@@_in_label_or_minipage_bool| will be raised if we are just after a |\item|
+% of a list of LaTeX or at the beginning of a |{minipage}|.
+% \begin{macrocode}
+%<*LaTeX>
+\bool_new:N \l_@@_in_label_or_minipage_bool
+%</LaTeX>
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+%<*LaTeX>
+\NewDocumentEnvironment { DispWithArrows } { ! d < > ! O { } }
+%</LaTeX>
+%<*plain-TeX>
+\cs_new_protected:Npn \DispWithArrows
+ {
+ \group_begin:
+ \peek_meaning:NTF <
+ { \DispWithArrows_i }
+ { \DispWithArrows_i < \c_novalue_tl > }
+ }
+\cs_new_protected:Npn \DispWithArrows_i < #1 >
+ {
+ \peek_meaning:NTF [
+ { \DispWithArrows_ii < #1 > }
+ { \DispWithArrows_ii < #1 > [ ] }
+ }
+\cs_new_protected:Npn \DispWithArrows_ii < #1 > [ #2 ]
+%</plain-TeX>
+ {
+ \bool_set_true:N \l_@@_in_DispWithArrows_bool
+%<*plain-TeX>
+ \str_clear_new:N \l_@@_type_env_str
+ \str_set:Nn \l_@@_type_env_str { DispWithArrows }
+%</plain-TeX>
+% \end{macrocode}
+% If \pkg{mathtools} has been loaded with the option |showonlyrefs|, we disable
+% the code of \pkg{mathtools} for the option |showonlyrefs| with the command
+% |\MT_showonlyrefs_false:| (it will be reactivated at the end of the
+% environment).
+% \begin{macrocode}
+%<*LaTeX>
+ \bool_if:nT \c_@@_mathtools_loaded_bool
+ {
+ \MH_if_boolean:nT { show_only_refs }
+ {
+ \MT_showonlyrefs_false:
+% \end{macrocode}
+% However, we have to re-raise the flag |{show_only_refs}| of \pkg{mhsetup}
+% because it has been switched off by |\MT_showonlyrefs_false:| and we will use
+% it in the code of the new version of |\label|.
+% \begin{macrocode}
+ \MH_set_boolean_T:n { show_only_refs }
+ }
+ }
+% \end{macrocode}
+%
+% An action done by \pkg{typedref} in its redefinition of |\refstepcounter|. The
+% command |\sr@name| is a prefix added to the name of the label by the
+% redefinition of |\label| done by \pkg{typedref}.
+% \begin{macrocode}
+ \bool_if:NT \c_@@_typedref_loaded_bool { \str_set:Nn \sr@name { equation } }
+% \end{macrocode}
+%
+% The command |\intertext@| is a command of \pkg{amsmath} which loads the
+% definition of |\intertext|.
+% \begin{macrocode}
+ \bool_if:NT \c_@@_amsmath_loaded_bool \intertext@
+%</LaTeX>
+ \exp_args:No \tl_if_novalue:nF { #1 } { \tl_set:Nn \l_@@_left_brace_tl { #1 } }
+ \@@_pre_halign:n { #2 }
+% \end{macrocode}
+%
+% If |subequations| is used, we encapsulate the environment in an
+% environment |{subequations}| of \pkg{amsmath}.
+% \begin{macrocode}
+%<*LaTeX>
+ \bool_if:NT \l_@@_subequations_bool { \begin { subequations } }
+%</LaTeX>
+% \end{macrocode}
+% Since the version 1.16 of \pkg{witharrows}, no space is added between an
+% |\item| of a LaTeX list and an environment |{DispWithArrows}| except with the
+% option |standard-behaviour-with-items| stored in the boolean
+% |\l_@@_sbwi_bool|. We have to know if we are just after an |\item| and this
+% information will be stored in |\l_@@_in_label_or_minipage_bool|.
+% \begin{macrocode}
+%<*LaTeX>
+ \bool_if:NF \l_@@_sbwi_bool
+ {
+ \if@inlabel
+ \bool_set_true:N \l_@@_in_label_or_minipage_bool
+ \fi
+ \if@minipage
+ \bool_set_true:N \l_@@_in_label_or_minipage_bool
+ \fi
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+ \tl_if_eq:NNF \l_@@_left_brace_tl \c_novalue_tl
+ {
+% \end{macrocode}
+% We compute the value of the width of the left delimiter.
+% \begin{macrocode}
+ \hbox_set:Nn \l_tmpa_box
+ {
+% \end{macrocode}
+% Even if the default value of |\nulldelimiterspace| is 1.2~pt, we take it into account.
+% \begin{macrocode}
+ \group_begin:
+ \dim_set_eq:NN \nulldelimiterspace \c_zero_dim
+ \c_math_toggle_token
+ \left \l_@@_replace_left_brace_by_tl \vcenter to 1 cm { } \right.
+ \c_math_toggle_token
+ \group_end:
+ }
+ \dim_zero_new:N \l_@@_delim_wd_dim
+ \dim_set:Nn \l_@@_delim_wd_dim { \box_wd:N \l_tmpa_box }
+ \box_clear_new:N \l_@@_left_brace_box
+ \hbox_set:Nn \l_@@_left_brace_box
+ {
+ \group_begin:
+ \cs_set_eq:NN \label \@@_old_label
+ \c_math_toggle_token
+ \bool_if:NT \l_@@_displaystyle_bool \displaystyle
+ \l_@@_left_brace_tl
+ { }
+ \c_math_toggle_token
+ \group_end:
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The token list |\l_@@_tag_tl| will contain the argument of the command |\tag|.
+% \begin{macrocode}
+%<*LaTeX>
+ \tl_clear_new:N \l_@@_tag_tl
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+ \bool_set_false:N \l_@@_qedhere_bool
+% \end{macrocode}
+%
+% \bigskip
+% The boolean |\l_@@_tag_star_bool| will be raised if the user uses the command
+% |\tag| with a star.
+% \begin{macrocode}
+ \bool_set_false:N \l_@@_tag_star_bool
+%</LaTeX>
+% \end{macrocode}
+%
+% \begin{macrocode}
+ \if_mode_math:
+ \@@_fatal:n { DispWithArrows~in~math~mode }
+ \fi:
+% \end{macrocode}
+%
+% \bigskip
+% The construction is not exactly the same whether we are just after an |\item|
+% of a LaTeX list or not. We know if we are after an |\item| thanks to the
+% boolean |\l_@@_in_label_or_minipage_bool|.
+% \begin{macrocode}
+%<*plain-TeX>
+ \dim_zero_new:N \linewidth
+ \dim_set_eq:NN \linewidth \displaywidth
+%</plain-TeX>
+%<*LaTeX>
+ \bool_if:NTF \l_@@_in_label_or_minipage_bool
+ { \c_math_toggle_token }
+ {
+%</LaTeX>
+% \end{macrocode}
+% We don't use |\[| of LaTeX because some extensions, like \pkg{autonum}, do a
+% redefinition of |\[|. However, we put the following lines which are in the
+% definition of |\[| even though they are in case of misuse.
+% \begin{macrocode}
+ \if_mode_vertical:
+ \nointerlineskip
+ \hbox_to_wd:nn { .6 \linewidth } { }
+ \fi:
+ \c_math_toggle_token \c_math_toggle_token
+%<*LaTeX>
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+% \begin{macrocode}
+ \dim_zero_new:N \l_@@_linewidth_dim
+%<*LaTeX>
+ \bool_if:NTF \l_@@_in_label_or_minipage_bool
+ { \dim_set_eq:NN \l_@@_linewidth_dim \linewidth }
+ { \dim_set_eq:NN \l_@@_linewidth_dim \displaywidth }
+%</LaTeX>
+%<*plain-TeX>
+ \dim_set_eq:NN \l_@@_linewidth_dim \displaywidth
+%</plain-TeX>
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+ \box_clear_new:N \l_@@_halign_box
+ \setbox \l_@@_halign_box \vtop \bgroup
+ \tabskip =
+ \bool_if:NTF \l_@@_fleqn_bool
+ \c_zero_skip
+ { 0 pt plus 1000 pt minus 1000 pt }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+ \@@_construct_halign:
+ \tabskip = 0 pt plus 1000 pt minus 1000 pt
+ &
+% \end{macrocode}
+%
+% If the user tries to use more columns than the length of the format, we have to
+% raise an error. However, the error won't be in the next column which is the
+% columns for the labels of the equations. The error will be after... and it
+% must be after. That means that we must not have an error in the next column
+% simply because we are not in math mode. That's why this column, even if it is
+% for the labels, is in math mode.
+% \begin{macrocode}
+ $ ## $
+ \tabskip = \c_zero_skip
+ &&
+ \@@_fatal:n { Too~much~columns~in~DispWithArrows }
+ \bool_if:nT \c_false_bool { ## }
+ \cr
+ }
+% \end{macrocode}
+%
+% \bigskip
+% We begin the second part of the environment |{DispWithArrows}|.
+% \begin{macrocode}
+%<*plain-TeX>
+\cs_new_protected:Npn \endDispWithArrows
+%</plain-TeX>
+ {
+%<*LaTeX>
+ \clist_if_in:NnT \l_@@_tags_clist { last }
+ { \clist_set:Nn \l_@@_tags_clist { all } }
+%</LaTeX>
+ \\
+% \end{macrocode}
+% The following |\egroup| is for the |\halign|.
+% \begin{macrocode}
+ \egroup
+ \unskip \unpenalty \unskip \unpenalty
+ \box_set_to_last:N \l_tmpa_box
+ \nointerlineskip
+ \box_use:N \l_tmpa_box
+ \dim_gzero_new:N \g_@@_alignment_dim
+ \dim_gset:Nn \g_@@_alignment_dim { \box_wd:N \l_tmpa_box }
+ \box_clear_new:N \l_@@_new_box
+ \hbox_set:Nn \l_@@_new_box { \hbox_unpack_clear:N \l_tmpa_box }
+ \dim_compare:nNnT
+ { \box_wd:N \l_@@_new_box } < \g_@@_alignment_dim
+ { \dim_gset:Nn \g_@@_alignment_dim { \box_wd:N \l_@@_new_box } }
+% \end{macrocode}
+% The |\egroup| is for the box |\l_@@_halign_box|.
+% \begin{macrocode}
+ \egroup
+% \end{macrocode}
+%
+% \begin{macrocode}
+ \tl_if_eq:NNTF \l_@@_left_brace_tl \c_novalue_tl
+ { \box_use_drop:N \l_@@_halign_box }
+ {
+ \hbox_to_wd:nn \l_@@_linewidth_dim
+ {
+ \bool_if:NTF \l_@@_fleqn_bool
+ { \skip_horizontal:n \l_@@_mathindent_dim }
+ \hfil
+ \hbox_to_wd:nn \g_@@_alignment_dim
+ {
+ \box_use_drop:N \l_@@_left_brace_box
+ \dim_set:Nn \l_tmpa_dim
+ {
+ \box_ht:N \l_@@_halign_box
+ + \box_dp:N \l_@@_halign_box
+ }
+ \group_begin:
+ \dim_set_eq:NN \nulldelimiterspace \c_zero_dim
+ \c_math_toggle_token
+ \left \l_@@_replace_left_brace_by_tl
+ \vcenter to \l_tmpa_dim { \vfil }
+ \right.
+ \c_math_toggle_token
+ \group_end:
+ \hfil
+ }
+ \hfil
+ }
+ \skip_horizontal:n { - \l_@@_linewidth_dim }
+ \vcenter { \box_use_drop:N \l_@@_halign_box }
+ }
+% \end{macrocode}
+%
+% We compute the dimension |\g_@@_right_x_dim|. As a first approximation,
+% |\g_@@_right_x_dim| is the $x$-value of the right side of the current
+% composition box. In fact, we must take into account the potential labels of
+% the equations. That's why we compute |\g_@@_right_x_dim| with the |v|-nodes of
+% each row specifically built in this goal. |\g_@@_right_x_dim| is the minimal
+% value of the $x$-value of these nodes.
+% \begin{macrocode}
+ \dim_gzero_new:N \g_@@_right_x_dim
+ \dim_gset_eq:NN \g_@@_right_x_dim \c_max_dim
+%<*LaTeX>
+ \begin { tikzpicture } [ @@_standard ]
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture [ @@_standard ]
+%</plain-TeX>
+ \int_step_variable:nNn \g_@@_line_int \l_tmpa_int
+ {
+ \cs_if_free:cTF
+ { pgf@sh@ns@wa - \l_@@_prefix_str - \l_tmpa_int - v }
+ { \@@_fatal:n { Inexistent~v-node } }
+ {
+ \tikz@parse@node\pgfutil@firstofone ( \l_tmpa_int - v )
+ \dim_set:Nn \l_tmpa_dim \pgf@x
+ \dim_compare:nNnT \l_tmpa_dim < \g_@@_right_x_dim
+ { \dim_gset:Nn \g_@@_right_x_dim \l_tmpa_dim }
+ }
+ }
+%<*LaTeX>
+ \end { tikzpicture }
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+% \end{macrocode}
+%
+%
+% \bigskip
+% The code in |\@@_post_halign:| is common to |{WithArrows}| and
+% |{DispWithArrows}|.
+% \begin{macrocode}
+ \@@_post_halign:
+% \end{macrocode}
+% If \pkg{mathtools} has been loaded with the option |showonlyrefs|, we
+% reactivate the code of \pkg{mathtools} for the option |showonlyrefs| with the
+% command |\MT_showonlyrefs_true:| (it has been deactivated in the beginning of
+% the environment).
+% \begin{macrocode}
+%<*LaTeX>
+ \bool_if:nT \c_@@_mathtools_loaded_bool
+ { \MH_if_boolean:nT { show_only_refs } \MT_showonlyrefs_true: }
+ \bool_if:NTF \l_@@_in_label_or_minipage_bool
+ {
+ \c_math_toggle_token
+ \skip_vertical:N \belowdisplayskip
+ }
+ { \c_math_toggle_token \c_math_toggle_token }
+%</LaTeX>
+%<*plain-TeX>
+ \c_math_toggle_token \c_math_toggle_token
+%</plain-TeX>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*LaTeX>
+ \bool_if:NT \l_@@_subequations_bool { \end { subequations } }
+% \end{macrocode}
+%
+% \bigskip
+% If the option |footnote| or the option |footnotehyper| is used, then we
+% extract the footnotes with an environment |{savenotes}| (of the package
+% \pkg{footnote} or the package \pkg{footnotehyper}).
+% \begin{macrocode}
+ \bool_if:NT \g_@@_footnote_bool { \end { savenotes } }
+%</LaTeX>
+%<*plain-TeX>
+ \group_end:
+%</plain-TeX>
+%<*LaTeX>
+ \ignorespacesafterend
+%</LaTeX>
+ }
+% \end{macrocode}
+%
+% \bigskip
+% With the environment |{DispWithArrows*}|, the equations are not numbered. We
+% don't put |\begin{DispWithArrows}| and |\end{DispWithArrows}| because there is
+% a |\@currenvir| in some error messages.
+% \begin{macrocode}
+%<*LaTeX>
+\NewDocumentEnvironment { DispWithArrows* } { }
+ {
+ \WithArrowsOptions { notag }
+ \DispWithArrows
+ }
+ \endDispWithArrows
+%</LaTeX>
+% \end{macrocode}
+%
+%
+% \bigskip
+% \subsection{The commands \textbackslash tag, \textbackslash notag,
+% \textbackslash label, \textbackslash tagnextline and \textbackslash qedhere for
+% \{DispWithArrows\}}
+%
+% Some commands are allowed only in the last column of the environment
+% |{DispWithArrows}|. We write a command |\@@_if_in_last_col_of_disp:Nn| to
+% execute this command only if we are in the last column. If we are in
+% another column, an error is raised. The first argument of
+% |\@@_if_in_last_col_of_disp:Nn| is the name of the command used in the error
+% message and the second is the code to execute.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_if_in_last_col_of_disp:Nn #1 #2
+ {
+ \bool_if:NTF \l_@@_in_WithArrows_bool
+ { \@@_error:nn { Not~allowed~in~WithArrows } { #1 } }
+ {
+ \int_compare:nNnTF \g_@@_col_int < \l_@@_nb_cols_int
+ { \@@_error:nn { Not~allowed~in~DispWithArrows } { #1 } }
+ { #2 }
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_notag:| will be linked to the command |\notag| and also to
+% in the environments |{WithArrows}| and |{DispWithArrows}|.
+% \begin{macrocode}
+%<*LaTeX>
+\cs_new_protected:Npn \@@_notag:
+ { \@@_if_in_last_col_of_disp:Nn \notag { \clist_clear:N \l_@@_tags_clist } }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_nonumber:| will be linked to the command |\nonumber| and also to
+% in the environments |{WithArrows}| and |{DispWithArrows}|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_nonumber:
+ { \@@_if_in_last_col_of_disp:Nn \nonumber { \clist_clear:N \l_@@_tags_clist } }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_tag| will be linked to |\tag| in |{WithArrows}| and
+% |{DispWithArrows}|. We do the definition with |\NewDocumentCommand| because this
+% command has a starred version.
+% \begin{macrocode}
+\NewDocumentCommand \@@_tag { s m }
+ {
+ \@@_if_in_last_col_of_disp:Nn \tag
+ {
+ \tl_if_empty:NF \l_@@_tag_tl
+ { \@@_error:nn { Multiple~tags } { #2 } }
+ \clist_set:Nn \l_@@_tags_clist { all }
+ \bool_if:nT \c_@@_mathtools_loaded_bool
+ {
+ \MH_if_boolean:nT { show_only_refs }
+ {
+ \MH_if_boolean:nF { show_manual_tags }
+ { \clist_clear:N \l_@@_tags_clist }
+ }
+ }
+ \tl_set:Nn \l_@@_tag_tl { #2 }
+ \bool_set:Nn \l_@@_tag_star_bool { #1 }
+% \end{macrocode}
+% The starred version |\tag*| can't be used if \pkg{amsmath} has not been loaded
+% because this version does the job by deactivating the command |\tagform@|
+% inserted by \pkg{amsmath} in the (two versions of the) command
+% |\@eqnnum|.\footnote{There are two versions of |@eqnnum|, a standard version
+% and a version for the option |leqno|.}
+% \begin{macrocode}
+ \bool_if:nT { #1 && ! \bool_if_p:N \c_@@_amsmath_loaded_bool }
+ { \@@_error:n { tag*~without~amsmath } }
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_label:n| will be linked to |\label| in the environments
+% |{WithArrows}| and |{DispWithArrows}|. In these environments, it's possible to
+% put several labels for the same line (it's not possible in the environments of
+% \pkg{amsmath}). That's why we store the differents labels of a same line in a
+% sequence |\l_@@_labels_seq|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_label:n #1
+ {
+ \@@_if_in_last_col_of_disp:Nn \label
+ {
+ \seq_if_empty:NF \l_@@_labels_seq
+ {
+ \bool_if:NTF \c_@@_cleveref_loaded_bool
+ { \@@_error:n { Multiple~labels~with~cleveref } }
+ { \@@_error:n { Multiple~labels } }
+ }
+ \seq_put_right:Nn \l_@@_labels_seq { #1 }
+ \bool_if:nT \c_@@_mathtools_loaded_bool
+ {
+ \MH_if_boolean:nT { show_only_refs }
+ {
+ \cs_if_exist:cTF { MT_r_#1 }
+ { \clist_set:Nn \l_@@_tags_clist { all } }
+ { \clist_clear:N \l_@@_tags_clist }
+ }
+ }
+ \bool_if:nT \c_@@_autonum_loaded_bool
+ {
+ \cs_if_exist:cTF { autonum@#1Referenced }
+ { \clist_set:Nn \l_@@_tags_clist { all } }
+ { \clist_clear:N \l_@@_tags_clist }
+ }
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_tagnextline:| will be linked to |\tagnextline| in
+% |{DispWithArrows}|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_tagnextline:
+ {
+ \@@_if_in_last_col_of_disp:Nn \tagnextline
+ { \bool_set_true:N \l_@@_tag_next_line_bool }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% The environments |{DispWithArrows}| and |{DispWithArrows*}| are compliant with
+% the command |\qedhere| of \pkg{amsthm}. However, this compatibility requires a
+% special version of |\qedhere|.
+%
+% This special version is called |\@@_qedhere:| and will be linked with
+% |\qedhere| in the last column of the environment |{DispWithArrows}| (only if
+% the package \pkg{amsthm} has been loaded). |\@@_qedhere:| raises the boolean
+% |\l_@@_qedhere_bool|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_qedhere: { \bool_set_true:N \l_@@_qedhere_bool }
+\cs_new_protected:Npn \@@_set_qedhere: { \cs_set_eq:NN \qedhere \@@_qedhere: }
+% \end{macrocode}
+%
+% In the last column of the |\halign| of |{DispWithArrows}| (column of the
+% labels, that is to say the numbers of the equations), a command
+% |\@@_qedhere_i:| will be issued if the flag |\l_@@_qedhere_bool| has been
+% raised. The code of this command is an adaptation of the code of |\qedhere| in
+% \pkg{amsthm}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_qedhere_i:
+ {
+ \group_begin:
+ \cs_set_eq:NN \qed \qedsymbol
+% \end{macrocode}
+% The line |\cs_set_eq:NN \qed@elt \setQED@elt| is a preparation for an action
+% on the \textsc{qed} stack. Despite its form, the instruction |\QED@stack|
+% executes an operation on the stack. This operation prints the \textsc{qed}
+% symbol and nullify the top of the stack.
+% \begin{macrocode}
+ \cs_set_eq:NN \qed@elt \setQED@elt
+ \QED@stack \relax \relax
+ \group_end:
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+%
+%
+%
+% \subsection{We draw the arrows}
+%
+% \bigskip
+% The arrows are divided in groups. There is two reasons for this division.
+% \begin{itemize}
+% \item If the option |group| or the option |groups| is used, all the arrows of
+% a group are drawn on a same vertical at an abscissa of |\l_@@_x_dim|.
+% \item For aesthetic reasons, the starting point of all the starting arrows of
+% a group is raised upwards by the value |\l_@@_start_adjust_dim|. Idem for the
+% ending arrows.
+% \end{itemize}
+%
+% \medskip
+% If the option |group| is used (|\l_@@_pos_arrow_int| = 7), we scan the arrows
+% twice: in the first step we only compute the value of |\l_@@_x_dim| for the
+% whole group, and, in the second step (|\l_@@_pos_arrow_int| is set to 8), we
+% divide the arrows in groups (for the vertical adjustement) and we actually
+% draw the arrows.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_scan_arrows:
+ {
+ \group_begin:
+ \int_compare:nNnT \l_@@_pos_arrow_int = 7
+ {
+ \@@_scan_arrows_i:
+ \int_set:Nn \l_@@_pos_arrow_int 8
+ }
+ \@@_scan_arrows_i:
+ \group_end:
+ }
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_scan_arrows_i:
+ {
+% \end{macrocode}
+%
+% \bigskip
+% |\l_@@_first_arrow_of_group_int| will be the first arrow of the current group.
+%
+% |\l_@@_first_line_of_group_int| will be the first line involved in the group
+% of arrows (equal to the initial line of the first arrow of the group because
+% the option |jump| is always positive).
+%
+% |\l_@@_first_arrows_seq| will be the list the arrows of the group starting at
+% the first line of the group (we may have several arrows starting from the same
+% line). We have to know all these arrows because of the adjustement by
+% |\l_@@_start_adjust_dim|.
+%
+% |\l_@@_last_line_of_group_int| will be the last line involved in the group
+% (impossible to guess in advance).
+%
+% |\l_@@_last_arrows_seq| will be the list of all the arrows of the group
+% ending at the last line of the group (impossible to guess in advance).
+% \begin{macrocode}
+ \int_zero_new:N \l_@@_first_arrow_of_group_int
+ \int_zero_new:N \l_@@_first_line_of_group_int
+ \int_zero_new:N \l_@@_last_line_of_group_int
+ \seq_clear_new:N \l_@@_first_arrows_seq
+ \seq_clear_new:N \l_@@_last_arrows_seq
+% \end{macrocode}
+%
+% \medskip
+% The boolean |\l_@@_new_group_bool| is a switch that we will use the indicate
+% that a group is finished (and the lines of that group have to be drawn). This
+% boolean is not directed connected to the option |new-group| of an individual
+% arrow.
+% \begin{macrocode}
+ \bool_set_true:N \l_@@_new_group_bool
+% \end{macrocode}
+%
+% \bigskip
+% We begin a loop over all the arrows of the environment. Inside this loop, if a
+% group is finished, we will draw the arrows of that group.
+% \begin{macrocode}
+ \int_set:Nn \l_@@_arrow_int \c_one_int
+ \int_until_do:nNnn \l_@@_arrow_int > \g_@@_arrow_int
+ {
+% \end{macrocode}
+%
+% \bigskip
+% We extract from the property list of the current arrow the fields ``initial'',
+% ``final'', ``status'' and ``input-line''. For the two former, we have to do
+% conversions to integers.
+% \begin{macrocode}
+ \prop_get:cnN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { initial } \l_tmpa_tl
+ \int_set:Nn \l_@@_initial_int \l_tmpa_tl
+ \prop_get:cnN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { final } \l_tmpa_tl
+ \int_set:Nn \l_@@_final_int \l_tmpa_tl
+ \prop_get:cnN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { status } \l_@@_status_arrow_str
+ \prop_get:cnN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { input-line } \l_@@_input_line_str
+% \end{macrocode}
+%
+% \bigskip
+% We recall that, after the construction of the |\halign|, |\g_@@_line_int| is
+% the total number of lines of the environment. Therefore, the conditionnal
+% |\l_@@_final_int > \g_@@_line_int| tests whether an arrow arrives after the
+% last line of the environment. In this case, we raise an error (except in the
+% second step of treatment for the option |group|). The arrow will be completely
+% ignored, even for the computation of |\l_@@_x_dim|.
+% \begin{macrocode}
+ \int_compare:nNnTF \l_@@_final_int > \g_@@_line_int
+ {
+ \int_compare:nNnF \l_@@_pos_arrow_int = 8
+ { \@@_error:n { Too~few~lines~for~an~arrow } }
+ }
+ \@@_code_for_possible_arrow:
+% \end{macrocode}
+%
+% \bigskip
+% Incrementation of the index of the loop (and end of the loop).
+% \begin{macrocode}
+ \int_incr:N \l_@@_arrow_int
+ }
+% \end{macrocode}
+%
+% \bigskip
+% After the last arrow of the environment, we have to draw the last group of
+% arrows. If we are in option |group| and in the first step of treatment
+% (|\l_@@_pos_arrow_int| = 7), we don't draw because, in the first step, we
+% don't draw anything. If there is no arrow in the group, we don't draw (this
+% situation occurs when all the arrows of the potential group arrive after the
+% last line of the environment).
+% \begin{macrocode}
+ \bool_if:nT
+ {
+ \int_compare_p:n { \l_@@_pos_arrow_int != 7 }
+ &&
+ \int_compare_p:nNn \l_@@_first_arrow_of_group_int > 0
+ }
+ { \@@_draw_arrows:nn \l_@@_first_arrow_of_group_int \g_@@_arrow_int }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_code_for_possible_arrow:
+ {
+% \end{macrocode}
+% We test whether the previous arrow was in fact the last arrow of a group. In
+% this case, we have to draw all the arrows of that group, except if we are with
+% the option |group| and in the first step of treatment (|\l_@@_pos_arrow_int| =
+% 7).
+% \begin{macrocode}
+ \bool_if:nT
+ {
+ \int_compare_p:nNn \l_@@_arrow_int > \c_one_int
+ &&
+ ( \int_compare_p:n { \l_@@_initial_int > \l_@@_last_line_of_group_int }
+ &&
+ \int_compare_p:n { \l_@@_pos_arrow_int != 7 }
+ ||
+ \str_if_eq_p:Vn \l_@@_status_arrow_str { new-group }
+ )
+ }
+ {
+ \int_compare:nNnF \l_@@_first_arrow_of_group_int = \c_zero_int
+ {
+ \@@_draw_arrows:nn
+ \l_@@_first_arrow_of_group_int
+ { \l_@@_arrow_int - 1 }
+ }
+ \bool_set_true:N \l_@@_new_group_bool
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The flag |\l_@@_new_group_bool| indicates if we have to begin a new group of
+% arrows. In fact, we have to begin a new group in three circonstancies: if we
+% are at the first arrow of the environment (that's why the flag is raised
+% before the beginning of the loop), if we have just finished a group (that's
+% why the flag is raised in the previous conditionnal, for topological reasons
+% or if the previous arrows had the status ``new-group''). At the beginning of a
+% group, we have to initialize the following variables: |\l_@@_first_arrow_int|,
+% |\l_@@_first_line_of_group_int|, |\l_@@_last_line_of_group|,
+% |\l_@@_first_arrows_seq|, |\l_@@_last_arrows_seq|.
+%
+% \begin{macrocode}
+ \bool_if:nTF \l_@@_new_group_bool
+ {
+ \bool_set_false:N \l_@@_new_group_bool
+ \int_set_eq:NN \l_@@_first_arrow_of_group_int \l_@@_arrow_int
+ \int_set_eq:NN \l_@@_first_line_of_group_int \l_@@_initial_int
+ \int_set_eq:NN \l_@@_last_line_of_group_int \l_@@_final_int
+ \seq_clear:N \l_@@_first_arrows_seq
+ \seq_put_left:NV \l_@@_first_arrows_seq \l_@@_arrow_int
+ \seq_clear:N \l_@@_last_arrows_seq
+ \seq_put_left:NV \l_@@_last_arrows_seq \l_@@_arrow_int
+% \end{macrocode}
+%
+% If we are in option |group| and in the second step of treatment
+% (|\l_@@_pos_arrow_int| = 8), we don't initialize |\l_@@_x_dim| because we want
+% to use the same value of |\l_@@_x_dim| (computed during the first step) for
+% all the groups.
+% \begin{macrocode}
+ \int_compare:nT { \l_@@_pos_arrow_int != 8 }
+ { \dim_set:Nn \l_@@_x_dim { - \c_max_dim } }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% If we are not at the beginning of a new group.
+% \begin{macrocode}
+ {
+% \end{macrocode}
+%
+% If the arrow is independent, we don't take into account this arrow for the
+% detection of the end of the group.
+% \begin{macrocode}
+ \bool_if:nF
+ { \str_if_eq_p:Vn \l_@@_status_arrow_str { independent } }
+ {
+% \end{macrocode}
+% If the arrow is not independant, the arrow belongs to the current group and we
+% have to take it into account in some variables.
+% \begin{macrocode}
+ \int_compare:nT
+ { \l_@@_initial_int = \l_@@_first_line_of_group_int }
+ { \seq_put_left:NV \l_@@_first_arrows_seq \l_@@_arrow_int }
+ \int_compare:nNnTF \l_@@_final_int > \l_@@_last_line_of_group_int
+ {
+ \int_set_eq:NN \l_@@_last_line_of_group_int \l_@@_final_int
+ \seq_clear:N \l_@@_last_arrows_seq
+ \seq_put_left:NV \l_@@_last_arrows_seq \l_@@_arrow_int
+ }
+ {
+ \int_compare:nNnT \l_@@_final_int = \l_@@_last_line_of_group_int
+ { \seq_put_left:NV \l_@@_last_arrows_seq \l_@@_arrow_int }
+ }
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% If the arrow is not independent, we update the current $x$-value (in
+% |\l_@@_x_dim|) with the dedicated command |\@@_update_x:nn|. If we are
+% in option |group| and in the second step of treatment (|\l_@@_pos_arrow_int| =
+% 8), we don't initialize |\l_@@_x_dim| because we want to use the same value of
+% |\l_@@_x_dim| (computed during the first step) for all the groups.
+% \begin{macrocode}
+ \bool_if:nF { \str_if_eq_p:Vn \l_@@_status_arrow_str { independent } }
+ {
+ \int_compare:nT { \l_@@_pos_arrow_int != 8 }
+ { \@@_update_x:nn \l_@@_initial_int \l_@@_final_int }
+ }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% The following code is necessary because we will have to expand an argument
+% exactly 3 times.
+% \begin{macrocode}
+\cs_generate_variant:Nn \keys_set:nn { n o }
+\cs_new_protected:Npn \@@_keys_set:
+ { \keys_set_known:no { WithArrows / Arrow / SecondPass } }
+% \end{macrocode}
+%
+% \bigskip
+% The macro |\@@_draw_arrows:nn| draws all the arrows whose numbers are between
+% |#1| and |#2|. |#1| and |#2| must be expressions that expands to an integer
+% (they are expanded in the beginning of the macro). This macro is nullified by
+% the option |no-arrows|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_draw_arrows:nn #1 #2
+ {
+ \group_begin:
+ \int_zero_new:N \l_@@_first_arrow_int
+ \int_set:Nn \l_@@_first_arrow_int { #1 }
+ \int_zero_new:N \l_@@_last_arrow_int
+ \int_set:Nn \l_@@_last_arrow_int { #2 }
+% \end{macrocode}
+%
+% \bigskip
+% We begin a loop over the arrows we have to draw. The variable
+% |\l_@@_arrow_int| (local in the environment |{WithArrows}|) will be used as
+% index for the loop.
+% \begin{macrocode}
+ \int_set:Nn \l_@@_arrow_int \l_@@_first_arrow_int
+ \int_until_do:nNnn \l_@@_arrow_int > \l_@@_last_arrow_int
+ {
+% \end{macrocode}
+%
+% \bigskip
+% We extract from the property list of the current arrow the fields ``initial''
+% and ``final'' and we store these values in |\l_@@_initial_int| and
+% |\l_@@_final_int|. However, we have to do a conversion because the components
+% of a property list are token lists.
+% \begin{macrocode}
+ \prop_get:cnN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { initial } \l_tmpa_tl
+ \int_set:Nn \l_@@_initial_int \l_tmpa_tl
+ \prop_get:cnN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { final } \l_tmpa_tl
+ \int_set:Nn \l_@@_final_int \l_tmpa_tl
+% \end{macrocode}
+%
+% \bigskip
+% If the arrow ends after the last line of the environment, we don't draw the
+% arrow (an error has already been raised in |\@@_scan_arrows:|). We recall
+% that, after the construction of the |\halign|, |\g_@@_line_int| is the total
+% number of lines of the environment).
+% \begin{macrocode}
+ \int_compare:nT { \l_@@_final_int <= \g_@@_line_int } \@@_draw_arrows_i:
+ \int_incr:N \l_@@_arrow_int
+ }
+ \group_end:
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The macro |\@@_draw_arrows_i:| is only for the lisibility of the code. The
+% first |\group_begin:| is for the options of the arrows (but we remind that the
+% options |ll|, |rr|, |rl|, |lr|, |i| and |jump| have already been extracted and
+% are not present in the field |options| of the property list of the arrow).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_draw_arrows_i:
+ {
+ \group_begin:
+% \end{macrocode}
+%
+% \bigskip
+% We process the options of the current arrow. The second argument of
+% |\keys_set:nn| must be expanded exactly three times. An x-expansion is not
+% possible because there can be tokens like |\bfseries| in the option |font| of
+% the option |tikz|. This expansion is a bit tricky.
+% \begin{macrocode}
+ \prop_get:cnN
+ { g_@@_arrow _\l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { options } \l_tmpa_tl
+ \str_clear_new:N \l_@@_previous_key_str
+ \exp_args:NNo \exp_args:No
+ \@@_keys_set: { \l_tmpa_tl , tikz = { xshift = \l_@@_xoffset_dim } }
+% \end{macrocode}
+%
+% We create two booleans to indicate the position of the initial node and final
+% node of the arrow in cases of options |rr|, |rl|, |lr| or |ll|:
+% \begin{macrocode}
+ \bool_set_false:N \l_@@_initial_r_bool
+ \bool_set_false:N \l_@@_final_r_bool
+ \int_case:nn \l_@@_pos_arrow_int
+ {
+ 0 { \bool_set_true:N \l_@@_final_r_bool }
+ 2 { \bool_set_true:N \l_@@_initial_r_bool }
+ 3
+ {
+ \bool_set_true:N \l_@@_initial_r_bool
+ \bool_set_true:N \l_@@_final_r_bool
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% \begin{center}
+% \begin{tabular}{l}
+% \begin{tabular}{@{}l*8c@{}}
+% \toprule
+% option & |lr| & |ll| & |rl| & |rr| & |v| & |i| & |groups| & |group| \\
+% \midrule
+% |\l_@@_pos_arrow_int| & $0$ & $1$ & $2$ & $3$ & $4$ & $5$ & $6$ & $7$ \\
+% \bottomrule
+% \end{tabular} \\
+% \footnotesize The option |v| can be used only in |\Arrow| in |code-after| (see
+% below).
+% \end{tabular}
+% \end{center}
+%
+% \bigskip
+% In case of option |i| at a local or global level (|\l_@@_pos_arrow_int| = 5),
+% we have to compute the $x$-value of the arrow (which is vertical). The
+% computed $x$-value is stored in |\l_@@_x_dim| (the same variable used when the
+% option |group| or the option |groups| is used).
+% \begin{macrocode}
+ \int_compare:nNnT \l_@@_pos_arrow_int = 5
+ {
+ \dim_set:Nn \l_@@_x_dim { - \c_max_dim }
+ \@@_update_x:nn \l_@@_initial_int \l_@@_final_int
+ }
+% \end{macrocode}
+%
+% \bigskip
+% |\l_@@_initial_tl| contains the name of the Tikz node from which the arrow
+% starts (in normal cases... because with the option |i|, |group| and |groups|,
+% the point will perhaps have another
+% $x$-value --- but always the same $y$-value). Idem for |\l_@@_final_tl|.
+% \begin{macrocode}
+ \tl_set:Nx \l_@@_initial_tl
+ {
+ \int_use:N \l_@@_initial_int - \bool_if:NTF \l_@@_initial_r_bool rl
+ .south
+ }
+ \tl_set:Nx \l_@@_final_tl
+ { \int_use:N \l_@@_final_int - \bool_if:NTF \l_@@_final_r_bool rl .north }
+% \end{macrocode}
+% We use ``|.south|'' and ``|.north|'' because we want a small gap between two
+% consecutive arrows (and the Tikz nodes created have the shape of small
+% vertical segments: use option |show-nodes| to visualize the nodes).
+%
+% \bigskip
+% The label of the arrow will be stored in |\l_tmpa_tl|.
+% \begin{macrocode}
+ \prop_get:cnN
+ { g_@@_arrow _ \l_@@_prefix_str _ \int_use:N \l_@@_arrow_int _ prop }
+ { label }
+ \l_tmpa_tl
+% \end{macrocode}
+%
+% \bigskip
+% Now, we have to know if the arrow starts at the first line of the group and/or
+% ends at the last line of the group. That's the reason why we have stored in
+% |\l_@@_first_arrows_seq| the list of all the arrows starting at the
+% first line of the group and in |\l_@@_last_arrows_seq| the list of
+% all the arrows ending at the last line of the group. We compute these values
+% in the booleans |\l_tmpa_bool| and |\l_tmpb_bool|. These computations can't be
+% done in the following |{tikzpicture}| because the command |\seq_if_in:NnTF|
+% which is \emph{not} expandable.
+% \begin{macrocode}
+ \seq_if_in:NxTF \l_@@_first_arrows_seq
+ { \int_use:N \l_@@_arrow_int }
+ { \bool_set_true:N \l_tmpa_bool }
+ { \bool_set_false:N \l_tmpa_bool }
+ \seq_if_in:NxTF \l_@@_last_arrows_seq
+ { \int_use:N \l_@@_arrow_int }
+ { \bool_set_true:N \l_tmpb_bool }
+ { \bool_set_false:N \l_tmpb_bool }
+ \int_compare:nNnT \l_@@_pos_arrow_int = 5
+ {
+ \bool_set_true:N \l_tmpa_bool
+ \bool_set_true:N \l_tmpb_bool
+ }
+% \end{macrocode}
+%
+% \bigskip
+% We compute and store in |\g_tmpa_tl| and |\g_tmpb_tl| the exact coordinates of
+% the extremities of the arrow.
+% \begin{itemize}
+% \item Concerning the
+% $x$-values, the abscissa computed in |\l_@@_x_dim| will be used if the option
+% of position is |i|, |group| or |groups|.
+% \item Concerning the
+% $y$-values, an adjustement is done for each arrow starting at the first line
+% of the group and each arrow ending at the last line of the group (with the
+% values of |\l_@@_start_adjust_dim| and |\l_@@_end_adjust_dim|).
+% \end{itemize}
+%
+% \begin{macrocode}
+%<*LaTeX>
+ \begin { tikzpicture } [ @@_standard ]
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture [ @@_standard ]
+%</plain-TeX>
+ \tikz@scan@one@point \pgfutil@firstofone ( \l_@@_initial_tl )
+ \tl_gset:Nx \g_tmpa_tl
+ {
+ \int_compare:nNnTF \l_@@_pos_arrow_int < 5
+ { \dim_use:N \pgf@x }
+ { \dim_use:N \l_@@_x_dim } ,
+ \bool_if:NTF \l_tmpa_bool
+ { \dim_eval:n { \pgf@y + \l_@@_start_adjust_dim } }
+ { \dim_use:N \pgf@y }
+ }
+ \tikz@scan@one@point \pgfutil@firstofone ( \l_@@_final_tl )
+ \tl_gset:Nx \g_tmpb_tl
+ {
+ \int_compare:nNnTF \l_@@_pos_arrow_int < 5
+ { \dim_use:N \pgf@x }
+ { \dim_use:N \l_@@_x_dim } ,
+ \bool_if:NTF \l_tmpb_bool
+ { \dim_eval:n { \pgf@y - \l_@@_end_adjust_dim } }
+ { \dim_use:N \pgf@y }
+ }
+%<*LaTeX>
+ \end { tikzpicture }
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+% \end{macrocode}
+%
+% \bigskip
+% Eventually, we can draw the arrow with the code in |\l_@@_tikz_code_tl|. We
+% recall that the value by default for this token list is :\enskip
+% ``\verb|\draw (#1) to node {#3} (#2) ;|''. This value can be modified with the
+% option |tikz-code|. We use the variant |\@@_draw_arrow:nno| of the macro
+% |\@@_draw_arrow:nnn| because of the characters \emph{underscore} in the name
+% |\l_tmpa_tl|: if the user uses the Tikz library |babel|, the third argument of
+% the command |\@@_draw_arrow:nno| will be rescanned because this third argument
+% will be in the argument of a command |node| of an instruction |\draw| of
+% Tikz... and we will have an error because of the characters
+% \emph{underscore}.\footnote{There were other solutions: use another name
+% without \emph{underscore} (like \Verb|\ltmpatl|) or use the package
+% \pkg{underscore} (with this package, the characters \emph{underscore} will be
+% rescanned without errors, even in text mode).}
+% \begin{macrocode}
+ \@@_draw_arrow:nno \g_tmpa_tl \g_tmpb_tl \l_tmpa_tl
+% \end{macrocode}
+%
+% \smallskip
+% We close the TeX group opened for the options given to |\Arrow[...]| (local
+% level of the options).
+% \begin{macrocode}
+ \group_end:
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% The function |@@_tmpa:nnn| will draw the arrow. It's merely an environment
+% |{tikzpicture}|. However, the Tikz instruction in this environment must be
+% inserted from |\l_@@_tikz_code_tl| with the markers |#1|, |#2| and |#3|.
+% That's why we create a function |\@@_def_function_tmpa:n| which will create
+% the function |\@@_tmpa:nnn|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_def_function_tmpa:n #1
+ {
+ \cs_set:Npn \@@_tmpa:nnn ##1 ##2 ##3
+ {
+%<*LaTeX>
+ \begin{tikzpicture}
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture
+%</plain-TeX>
+ [
+ @@_standard ,
+ every~path / .style = WithArrows / arrow
+ ]
+ #1
+%<*LaTeX>
+ \end{tikzpicture}
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+ }
+ }
+% \end{macrocode}
+%
+% \medskip
+% When we draw the arrow (with |\@@_draw_arrow:nnn|), we first create the
+% function |\@@_tmpa:nnn| and, then, we use the function |\@@_tmpa:nnn| :
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_draw_arrow:nnn #1 #2 #3
+ {
+% \end{macrocode}
+%
+% \medskip
+% If the option |wrap-lines| is used, we have to use a special version of
+% |\l_@@_tikz_code_tl| (which corresponds to the option |tikz-code|).
+% \begin{macrocode}
+ \bool_if:nT { \l_@@_wrap_lines_bool && \l_@@_in_DispWithArrows_bool }
+ { \tl_set_eq:NN \l_@@_tikz_code_tl \c_@@_tikz_code_wrap_lines_tl }
+% \end{macrocode}
+%
+% \medskip
+% Now, the main lines of this function |\@@_draw_arrow:nnn|.
+% \begin{macrocode}
+ \exp_args:NV \@@_def_function_tmpa:n \l_@@_tikz_code_tl
+ \@@_tmpa:nnn { #1 } { #2 } { #3 }
+ }
+\cs_generate_variant:Nn \@@_draw_arrow:nnn { n n o }
+% \end{macrocode}
+%
+% \bigskip
+% If the option |wrap-lines| is used, we have to use a special version of
+% |\l_@@_tikz_code_tl| (which corresponds to the option |tikz-code|).
+% \begin{macrocode}
+\tl_const:Nn \c_@@_tikz_code_wrap_lines_tl
+ {
+% \end{macrocode}
+% First, we draw the arrow without the label.
+% \begin{macrocode}
+ \draw ( #1 ) to node ( @@_label ) { } ( #2 ) ;
+% \end{macrocode}
+% We retrieve in |\pgf@x| the abscissa of the left-side of the label we will
+% put.
+% \begin{macrocode}
+ \tikz@parse@node \pgfutil@firstofone ( @@_label.west )
+% \end{macrocode}
+% We compute in |\l_tmpa_dim| the maximal width possible for the label.
+% Here is the use of |\g_@@_right_x_dim| which has been computed previously with
+% the |v|-nodes.
+% \begin{macrocode}
+ \dim_set:Nn \l_tmpa_dim
+ { \g_@@_right_x_dim - \pgf@x - \pgfkeysvalueof { / pgf / inner~xsep } }
+% \end{macrocode}
+% We retrieve in |\g_tmpa_tl| the current value of the Tikz parameter
+% ``|text width|''.\footnote{In fact, it's not the current value of
+% ``|text width|'': it's the value of ``|text width|'' set in the option |tikz|
+% provided by \pkg{witharrows}. These options are given to Tikz in a
+% ``|every path|''. That's why we have to retrieve it in a path.}
+% \begin{macrocode}
+ \path \pgfextra { \tl_gset:Nx \g_tmpa_tl \tikz@text@width } ;
+% \end{macrocode}
+% Maybe the current value of the parameter ``|text width|'' is shorter than
+% |\l_tmpa_dim|. In this case, we must use ``|text width|'' (we update
+% |\l_tmpa_dim|).
+% \begin{macrocode}
+ \tl_if_empty:NF \g_tmpa_tl
+ {
+ \dim_set:Nn \l_tmpb_dim \g_tmpa_tl
+ \dim_compare:nNnT \l_tmpb_dim < \l_tmpa_dim
+ { \dim_set_eq:NN \l_tmpa_dim \l_tmpb_dim }
+ }
+% \end{macrocode}
+% Now, we can put the label with the right value for ``|text width|''.
+% \begin{macrocode}
+ \dim_compare:nNnT \l_tmpa_dim > \c_zero_dim
+ {
+ \path ( @@_label.west )
+ node [ anchor = west , text~width = \dim_use:N \l_tmpa_dim ]
+ { #3 } ;
+ }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% The command |\@@_update_x:nn| will analyze the lines between |#1| and
+% |#2| in order to modify |\l_@@_x_dim| in consequence. More precisely,
+% |\l_@@_x_dim| is increased if a line longer than the current value of
+% |\l_@@_x_dim| is found. |\@@_update_x:nn| is used in |\@@_scan_arrows:|
+% (for options |group| and |groups|) and in |\@@_draw_arrows:nn| (for option
+% |i|).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_update_x:nn #1 #2
+ {
+ \int_step_inline:nnn { #1 } { #2 }
+ {
+%<*LaTeX>
+ \begin { tikzpicture } [ @@_standard ]
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture [ @@_standard ]
+%</plain-TeX>
+ \tikz@scan@one@point \pgfutil@firstofone ( ##1 - l )
+ \dim_gset:Nn \g_tmpa_dim { \dim_max:nn \l_@@_x_dim \pgf@x }
+%<*LaTeX>
+ \end { tikzpicture }
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+ \dim_set_eq:NN \l_@@_x_dim \g_tmpa_dim
+ }
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% The command |\WithArrowsLastEnv| is not used by the package \pkg{witharrows}.
+% It's only a facility given to the final user. It gives the number of the last
+% environment |{WithArrows}| at
+% level~$0$ (to the sense of the nested environments). This macro is fully
+% expandable and, thus, can be used directly in the name of a Tikz node.
+% \begin{macrocode}
+\cs_new:Npn \WithArrowsLastEnv { \int_use:N \g_@@_last_env_int }
+% \end{macrocode}
+%
+% \bigskip
+% \subsection{The command \textbackslash Arrow in code-after}
+%
+% The option |code-after| is an option of the environment |{WithArrows}| (this
+% option is only available at the environment level). In the option |code-after|,
+% one can use the command |Arrow| but it's a special version of the command
+% |Arrow|. For this special version (internally called |\@@_Arrow_code_after|),
+% we define a special set of keys called |WithArrows/Arrow/code-after|.
+%
+% \begin{macrocode}
+\keys_define:nn { WithArrows / Arrow / code-after }
+ {
+ tikz .code:n =
+ \tikzset { WithArrows / arrow / .append~style = { #1 } } ,
+ tikz .value_required:n = true ,
+ rr .value_forbidden:n = true ,
+ rr .code:n = \@@_fix_pos_option:n 0 ,
+ ll .value_forbidden:n = true,
+ ll .code:n = \@@_fix_pos_option:n 1 ,
+ rl .value_forbidden:n = true ,
+ rl .code:n = \@@_fix_pos_option:n 2 ,
+ lr .value_forbidden:n = true ,
+ lr .code:n = \@@_fix_pos_option:n 3 ,
+ v .value_forbidden:n = true ,
+ v .code:n = \@@_fix_pos_option:n 4 ,
+ tikz-code .tl_set:N = \l_@@_tikz_code_tl ,
+ tikz-code .value_required:n = true ,
+ xoffset .dim_set:N = \l_@@_xoffset_dim ,
+ xoffset .value_required:n = true ,
+ unknown .code:n =
+ \@@_sort_seq:N \l_@@_options_Arrow_code_after_seq
+ \@@_error:n { Unknown~option~Arrow~in~code-after }
+ }
+% \end{macrocode}
+%
+% \bigskip
+% A sequence of the options available in |\Arrow| in |code-after|. This sequence
+% will be used in the error messages and can be modified dynamically.
+% \begin{macrocode}
+\seq_new:N \l_@@_options_Arrow_code_after_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_Arrow_code_after_seq
+ { ll, lr, rl, rr, tikz, tikz-code, v, x, offset }
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+%<*LaTeX>
+\NewDocumentCommand \@@_Arrow_code_after { O { } m m m ! O { } }
+%</LaTeX>
+%<*plain-TeX>
+\cs_new_protected:Npn \@@_Arrow_code_after
+ {
+ \peek_meaning:NTF [
+ { \@@_Arrow_code_after_i }
+ { \@@_Arrow_code_after_i [ ] }
+ }
+\cs_new_protected:Npn \@@_Arrow_code_after_i [ #1 ] #2 #3 #4
+ {
+ \peek_meaning:NTF [
+ { \@@_Arrow_code_after_ii [ #1 ] { #2 } { #3 } { #4 } }
+ { \@@_Arrow_code_after_ii [ #1 ] { #2 } { #3 } { #4 } [ ] }
+ }
+\cs_new_protected:Npn \@@_Arrow_code_after_ii [ #1 ] #2 #3 #4 [ #5 ]
+%</plain-TeX>
+ {
+ \int_set:Nn \l_@@_pos_arrow_int 1
+ \str_clear_new:N \l_@@_previous_key_str
+ \group_begin:
+ \keys_set:nn { WithArrows / Arrow / code-after }
+ { #1, #5, tikz = { xshift = \l_@@_xoffset_dim } }
+ \bool_set_false:N \l_@@_initial_r_bool
+ \bool_set_false:N \l_@@_final_r_bool
+ \int_case:nn \l_@@_pos_arrow_int
+ {
+ 0
+ {
+ \bool_set_true:N \l_@@_initial_r_bool
+ \bool_set_true:N \l_@@_final_r_bool
+ }
+ 2 { \bool_set_true:N \l_@@_initial_r_bool }
+ 3 { \bool_set_true:N \l_@@_final_r_bool }
+ }
+% \end{macrocode}
+% We prevent drawing a arrow from a line to itself.
+% \begin{macrocode}
+ \tl_if_eq:nnTF { #2 } { #3 }
+ { \@@_error:nn { Both~lines~are~equal } { #2 } }
+% \end{macrocode}
+% We test whether the two Tikz nodes |(#2-l)| and |(#3-l)| really exist. If not,
+% the arrow won't be drawn.
+% \begin{macrocode}
+ {
+ \cs_if_free:cTF { pgf@sh@ns@wa - \l_@@_prefix_str - #2 - l }
+ { \@@_error:nx { Wrong~line~in~Arrow } { #2 } }
+ {
+ \cs_if_free:cTF { pgf@sh@ns@wa - \l_@@_prefix_str - #3 - l }
+ { \@@_error:nx { Wrong~line~in~Arrow } { #3 } }
+ {
+ \int_compare:nNnTF \l_@@_pos_arrow_int = 4
+ {
+%<*LaTeX>
+ \begin { tikzpicture } [ @@_standard ]
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture [ @@_standard ]
+%</plain-TeX>
+ \tikz@scan@one@point \pgfutil@firstofone (#2-l.south)
+ \dim_set_eq:NN \l_tmpa_dim \pgf@x
+ \dim_set_eq:NN \l_tmpb_dim \pgf@y
+ \tikz@scan@one@point \pgfutil@firstofone (#3-l.north)
+ \dim_set:Nn \l_tmpa_dim
+ { \dim_max:nn \l_tmpa_dim \pgf@x }
+ \tl_gset:Nx \g_tmpa_tl
+ { \dim_use:N \l_tmpa_dim , \dim_use:N \l_tmpb_dim }
+ \tl_gset:Nx \g_tmpb_tl
+ { \dim_use:N \l_tmpa_dim , \dim_use:N \pgf@y }
+%<*LaTeX>
+ \end { tikzpicture }
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+ }
+ {
+%<*LaTeX>
+ \begin { tikzpicture } [ @@_standard ]
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture [ @@_standard ]
+%</plain-TeX>
+ \tikz@scan@one@point \pgfutil@firstofone
+ ( #2-\bool_if:NTF\l_@@_initial_r_bool rl .south )
+ \tl_gset:Nx \g_tmpa_tl
+ { \dim_use:N \pgf@x , \dim_use:N \pgf@y }
+ \tikz@scan@one@point \pgfutil@firstofone
+ ( #3-\bool_if:NTF\l_@@_final_r_bool rl .north )
+ \tl_gset:Nx \g_tmpb_tl
+ { \dim_use:N \pgf@x , \dim_use:N \pgf@y }
+%<*LaTeX>
+ \end { tikzpicture }
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+ }
+ \@@_draw_arrow:nnn \g_tmpa_tl \g_tmpb_tl { #4 }
+ }
+ }
+ }
+ \group_end:
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% \subsection{The command \textbackslash MultiArrow in code-after}
+% The command |\@@_MultiArrow:nn| will be linked to |\MultiArrow| when the
+% |code-after| is executed.
+%
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_MultiArrow:nn #1 #2
+ {
+% \end{macrocode}
+% The user of the command |\MultiArrow| (in |code-after|) will be able to specify
+% the list of lines with the same syntax as the loop |\foreach| of \pkg{pgffor}.
+% That's why we construct a ``clist'' of \pkg{expl3} from the specification of
+% list given by the user. The construction of the ``clist'' must be global in
+% order to exit the |\foreach| and that's why we construct the list in
+% |\g_tmpa_clist|.
+% \begin{macrocode}
+ \foreach \x in { #1 }
+ {
+ \cs_if_free:cTF { pgf@sh@ns@wa - \l_@@_prefix_str - \x - l }
+ { \@@_error:nx { Wrong~line~specification~in~MultiArrow } \x }
+ { \clist_gput_right:Nx \g_tmpa_clist \x }
+ }
+% \end{macrocode}
+% We sort the list |\g_tmpa_clist| because we want to extract the minimum and
+% the maximum.
+% \begin{macrocode}
+ \int_compare:nTF { \clist_count:N \g_tmpa_clist < 2 }
+ { \@@_error:n { Too~small~specification~for~MultiArrow } }
+ {
+ \clist_sort:Nn \g_tmpa_clist
+ {
+ \int_compare:nTF { ##1 > ##2 }
+ \sort_return_swapped:
+ \sort_return_same:
+ }
+% \end{macrocode}
+% We extract the minimum in |\l_tmpa_tl| (it must be an integer but we store it
+% in a token list of \pkg{expl3}).
+% \begin{macrocode}
+ \clist_pop:NN \g_tmpa_clist \l_tmpa_tl
+% \end{macrocode}
+%
+% We extract the maximum in |\l_tmpb_tl|. The remaining list (in
+% |\g_tmpa_clist|) will be sorted in decreasing order but never mind...
+% \begin{macrocode}
+ \clist_reverse:N \g_tmpa_clist
+ \clist_pop:NN \g_tmpa_clist \l_tmpb_tl
+% \end{macrocode}
+%
+% We draw the teeth of the rak (except the first one and the last one) with the
+% auxiliary function |\@@_MultiArrow_i:n|. This auxiliary fonction is necessary
+% to expand the specification of the list in the |\foreach| loop. The first and
+% the last teeth of the rak can't be drawn the same way as the others (think,
+% for example, to the case of the option ``|rounded corners|'' is used).
+% \begin{macrocode}
+ \exp_args:NV \@@_MultiArrow_i:n \g_tmpa_clist
+% \end{macrocode}
+%
+% Now, we draw the rest of the structure.
+% \begin{macrocode}
+%<*LaTeX>
+ \begin { tikzpicture }
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture
+%</plain-TeX>
+ [
+ @@_standard ,
+ every~path / .style = { WithArrows / arrow }
+ ]
+ \draw [<->] ([xshift = \l_@@_xoffset_dim]\l_tmpa_tl-r.south)
+ -- ++(5mm,0)
+ -- node (@@_label) {}
+ ([xshift = \l_@@_xoffset_dim+5mm]\l_tmpb_tl-r.south)
+ -- ([xshift = \l_@@_xoffset_dim]\l_tmpb_tl-r.south) ;
+ \tikz@parse@node \pgfutil@firstofone (@@_label.west)
+ \dim_set:Nn \l_tmpa_dim { 20 cm }
+ \path \pgfextra { \tl_gset:Nx \g_tmpa_tl \tikz@text@width } ;
+ \tl_if_empty:NF \g_tmpa_tl { \dim_set:Nn \l_tmpa_dim \g_tmpa_tl }
+ \bool_if:nT { \l_@@_wrap_lines_bool && \l_@@_in_DispWithArrows_bool }
+ {
+ \dim_set:Nn \l_tmpb_dim
+ { \g_@@_right_x_dim - \pgf@x - 0.3333 em }
+ \dim_compare:nNnT \l_tmpb_dim < \l_tmpa_dim
+ { \dim_set_eq:NN \l_tmpa_dim \l_tmpb_dim }
+ }
+ \path (@@_label.west)
+ node [ anchor = west, text~width = \dim_use:N \l_tmpa_dim ] { #2 } ;
+%<*LaTeX>
+ \end{tikzpicture}
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+ }
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_MultiArrow_i:n #1
+ {
+%<*LaTeX>
+ \begin { tikzpicture }
+%</LaTeX>
+%<*plain-TeX>
+ \tikzpicture
+%</plain-TeX>
+ [
+ @@_standard ,
+ every~path / .style = { WithArrows / arrow }
+ ]
+ \foreach \k in { #1 }
+ {
+ \draw [ <- ]
+ ( [xshift = \l_@@_xoffset_dim]\k-r.south ) -- ++(5mm,0) ;
+ } ;
+%<*LaTeX>
+ \end{tikzpicture}
+%</LaTeX>
+%<*plain-TeX>
+ \endtikzpicture
+%</plain-TeX>
+ }
+% \end{macrocode}
+%
+%
+% \bigskip
+% \subsection{The error messages of the package}
+%
+% \begin{macrocode}
+\str_const:Nn \c_@@_option_ignored_str
+ { If~you~go~on,~this~option~will~be~ignored. }
+\str_const:Nn \c_@@_command_ignored_str
+ { If~you~go~on,~this~command~will~be~ignored. }
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*LaTeX>
+\@@_msg_new:nn { amsmath~not~loaded }
+ {
+ You~can't~use~the~option~'\l_keys_key_tl'~because~the~
+ package~'amsmath'~has~not~been~loaded.\\
+ If~you~go~on,~this~option~will~be~ignored~in~the~rest~
+ of~the~document.
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Bad~value~for~replace~brace~by }
+ {
+ Bad~value~for~the~option~'\l_keys_key_tl'.~The~value~must~begin~
+ with~an~extensible~left~delimiter.~The~possible~values~are:~.,
+ \token_to_str:N \{,~(,~[,~\token_to_str:N \lbrace,~
+ \token_to_str:N \lbrack,~\token_to_str:N \lgroup,~
+ \token_to_str:N \langle,~\token_to_str:N \lmoustache,~
+ \token_to_str:N \lfloor\ and~\token_to_str:N \lceil\
+ (and~\token_to_str:N \lvert\ and~\token_to_str:N \lVert\
+ if~amsmath~or~unicode-math~is~loaded~in~LaTeX).\\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { option~of~cr~negative }
+ {
+ The~argument~of~the~command~\token_to_str:N\\~
+ should~be~positive~in~the~row~\int_use:N \g_@@_line_int\
+ of~your~environment~\{\l_@@_type_env_str\}.\\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { omit~probably~used }
+ {
+ There~is~a~problem.~Maybe~you~have~used~a~command~
+ \token_to_str:N\omit\ in~the~line~\int_use:N \g_@@_line_int\
+ (or~another~line)~of~your~environment~\{\l_@@_type_env_str\}.\\
+ You~can~go~on~but~you~may~have~others~errors.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*LaTeX>
+\@@_msg_new:nn { newline~at~the~end~of~env }
+ {
+ Your~environment~\{\l_@@_type_env_str\}~should~not~end~with~
+ a~\token_to_str:N \\.\\
+ This~warning~might~become~an~error~in~a~future~version.
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Invalid~option~format }
+ {
+ The~key~'format'~should~contain~only~letters~r,~c~and~l~and~
+ must~not~be~empty.\\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Value~for~a~key }
+ {
+ The~key~'\l_keys_key_tl'~should~be~used~without~value. \\
+ However,~you~can~go~on~for~this~time.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~in~Arrow }
+ {
+ The~key~'\l_keys_key_tl'~is~unknown~for~the~command~
+ \l_@@_string_Arrow_for_msg_str\ in~the~row~
+ \int_use:N \g_@@_line_int\ of~your~environment~
+ \{\l_@@_type_env_str\}. \l_tmpa_str \\
+ \c_@@_option_ignored_str \\
+ For~a~list~of~the~available~keys,~type~H~<return>.
+ }
+ {
+ The~available~keys~are~(in~alphabetic~order):~
+ \seq_use:Nnnn \l_@@_options_Arrow_seq {~and~} {,~} {~and~}.
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~WithArrows }
+ {
+ The~key~'\l_keys_key_tl'~is~unknown~in~\{\l_@@_type_env_str\}. \\
+ \c_@@_option_ignored_str \\
+ For~a~list~of~the~available~keys,~type~H~<return>.
+ }
+ {
+ The~available~keys~are~(in~alphabetic~order):~
+ \seq_use:Nnnn \l_@@_options_WithArrows_seq {~and~} {,~} {~and~}.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~DispWithArrows }
+ {
+ The~key~'\l_keys_key_tl'~is~unknown~in~\{\l_@@_type_env_str\}. \\
+ \c_@@_option_ignored_str \\
+ For~a~list~of~the~available~keys,~type~H~<return>.
+ }
+ {
+ The~available~keys~are~(in~alphabetic~order):~
+ \seq_use:Nnnn \l_@@_options_DispWithArrows_seq {~and~} {,~} {~and~}.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~WithArrowsOptions }
+ {
+ The~key~'\l_keys_key_tl'~is~unknown~in~
+ \token_to_str:N \WithArrowsOptions. \\
+ \c_@@_option_ignored_str \\
+ For~a~list~of~the~available~keys,~type~H~<return>.
+ }
+ {
+ The~available~keys~are~(in~alphabetic~order):~
+ \seq_use:Nnnn \l_@@_options_WithArrowsOptions_seq {~and~} {,~} {~and~}.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~Arrow~in~code-after }
+ {
+ The~key~'\l_keys_key_tl'~is~unknown~in~
+ \token_to_str:N \Arrow\ in~code-after. \\
+ \c_@@_option_ignored_str \\
+ For~a~list~of~the~available~keys,~type~H~<return>.
+ }
+ {
+ The~available~keys~are~(in~alphabetic~order):~
+ \seq_use:Nnnn \l_@@_options_Arrow_code_after_seq {~and~} {,~} {~and~}.
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Too~much~columns~in~WithArrows }
+ {
+ Your~environment~\{\l_@@_type_env_str\}~has~\int_use:N
+ \l_@@_nb_cols_int\ columns~and~you~try~to~use~one~more.~
+ Maybe~you~have~forgotten~a~\c_backslash_str\c_backslash_str.~
+ If~you~really~want~to~use~more~columns~(after~the~arrows)~you~should~use~
+ the~option~'more-columns'~at~a~global~level~or~for~an~environment. \\
+ However,~you~can~go~one~for~this~time.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Too~much~columns~in~DispWithArrows }
+ {
+ Your~environment~\{\l_@@_type_env_str\}~has~\int_use:N
+ \l_@@_nb_cols_int\ columns~and~you~try~to~use~one~more.~
+ Maybe~you~have~forgotten~a~\c_backslash_str\c_backslash_str\
+ at~the~end~of~row~\int_use:N \g_@@_line_int. \\
+ This~error~is~fatal.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Negative~jump }
+ {
+ You~can't~use~a~negative~value~for~the~option~'jump'~of~command~
+ \l_@@_string_Arrow_for_msg_str\
+ in~the~row~\int_use:N \g_@@_line_int\
+ of~your~environment~\{\l_@@_type_env_str\}.~
+ You~can~create~an~arrow~going~backwards~with~the~option~'<-'~of~Tikz. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { new-group~without~groups }
+ {
+ You~can't~use~the~option~'new-group'~for~the~command~
+ \l_@@_string_Arrow_for_msg_str\
+ because~you~are~not~in~'groups'~mode.~Try~to~use~the~option~
+ 'groups'~in~your~environment~\{\l_@@_type_env_str\}. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nn
+ { Too~few~lines~for~an~arrow }
+ {
+ Line~\l_@@_input_line_str\
+ :~an~arrow~specified~in~the~row~\int_use:N \l_@@_initial_int\
+ of~your~environment~\{\l_@@_type_env_str\}~can't~be~drawn~
+ because~it~arrives~after~the~last~row~of~the~environment. \\
+ If~you~go~on,~this~arrow~will~be~ignored.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { WithArrows~outside~math~mode }
+ {
+ The~environment~\{\l_@@_type_env_str\}~should~be~used~only~in~math~mode~
+ like~the~environment~\{aligned\}~of~amsmath. \\
+ Nevertheless,~you~can~go~on.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { DispWithArrows~in~math~mode }
+ {
+ The~environment~\{\l_@@_type_env_str\}~should~be~used~only~outside~math~
+ mode~like~the~environment~\{align\}~of~amsmath. \\
+ This~error~is~fatal.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Incompatible~options~in~Arrow }
+ {
+ You~try~to~use~the~option~'\l_keys_key_tl'~but~
+ this~option~is~incompatible~or~redundant~with~the~option~
+ '\l_@@_previous_key_str'~set~in~the~same~command~
+ \l_@@_string_Arrow_for_msg_str. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Incompatible~options }
+ { You~try~to~use~the~option~'\l_keys_key_tl'~but~
+ this~option~is~incompatible~or~redundant~with~the~option~
+ '\l_@@_previous_key_str'~set~in~the~same~command~
+ \bool_if:NT \l_@@_in_code_after_bool
+ {
+ \l_@@_string_Arrow_for_msg_str\
+ in~the~code-after~of~your~environment~\{\l_@@_type_env_str\}
+ }. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Arrow~not~in~last~column }
+ {
+ You~should~use~the~command~\l_@@_string_Arrow_for_msg_str\
+ only~in~the~last~column~(column~\int_use:N\l_@@_nb_cols_int)~
+ of~your~environment~\{\l_@@_type_env_str\}.\\
+ However~you~can~go~on~for~this~time.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Wrong~line~in~Arrow }
+ {
+ The~specification~of~line~'#1'~you~use~in~the~command~
+ \l_@@_string_Arrow_for_msg_str\
+ in~the~'code-after'~of~\{\l_@@_type_env_str\}~doesn't~exist. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Both~lines~are~equal }
+ {
+ In~the~'code-after'~of~\{\l_@@_type_env_str\}~you~try~to~
+ draw~an~arrow~going~to~itself~from~the~line~'#1'.~This~is~not~possible. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Wrong~line~specification~in~MultiArrow }
+ {
+ The~specification~of~line~'#1'~doesn't~exist. \\
+ If~you~go~on,~it~will~be~ignored~for~\token_to_str:N \MultiArrow.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Too~small~specification~for~MultiArrow }
+ {
+ The~specification~of~lines~you~gave~to~\token_to_str:N \MultiArrow\
+ is~too~small:~you~need~at~least~two~lines. \\
+ \c_@@_command_ignored_str
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Not~allowed~in~DispWithArrows }
+ {
+ The~command~\token_to_str:N #1
+ is~allowed~only~in~the~last~column~
+ (column~\int_use:N\l_@@_nb_cols_int)~of~\{\l_@@_type_env_str\}. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Not~allowed~in~WithArrows }
+ {
+ The~command~\token_to_str:N #1 is~not~allowed~in~\{\l_@@_type_env_str\}~
+ (it's~allowed~in~the~last~column~of~\{DispWithArrows\}). \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*LaTeX>
+\@@_msg_new:nn { tag*~without~amsmath }
+ {
+ We~can't~use~\token_to_str:N\tag*~because~you~haven't~loaded~amsmath~
+ (or~mathtools). \\
+ If~you~go~on,~the~command~\token_to_str:N\tag\
+ will~be~used~instead.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Multiple~tags }
+ {
+ You~can't~use~twice~the~command~\token_to_str:N\tag\
+ in~a~line~of~the~environment~\{\l_@@_type_env_str\}. \\
+ If~you~go~on,~the~tag~'#1'~will~be~used.
+ }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Multiple~labels }
+ {
+ Normally,~we~can't~use~the~command~\token_to_str:N\label\
+ twice~in~a~line~of~the~environment~\{\l_@@_type_env_str\}. \\
+ However,~you~can~go~on.~
+ \bool_if:NT \c_@@_showlabels_loaded_bool
+ { However,~only~the~last~label~will~be~shown~by~showlabels.~ }
+ If~you~don't~want~to~see~this~message~again,~you~can~use~the~option~
+ 'allow-multiple-labels'~at~the~global~or~environment~level.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Multiple~labels~with~cleveref }
+ {
+ Since~you~use~cleveref,~you~can't~use~the~command~\token_to_str:N\label\
+ twice~in~a~line~of~the~environment~\{\l_@@_type_env_str\}. \\
+ If~you~go~on,~you~may~have~undefined~references.
+ }
+%</LaTeX>
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Inexistent~v-node }
+ {
+ There~is~a~problem.~Maybe~you~have~put~a~command~\token_to_str:N\cr\
+ instead~of~a~command~\token_to_str:N\\~at~the~end~of~
+ the~row~\l_tmpa_int\
+ of~your~environment~\{\l_@@_type_env_str\}. \\
+ This~error~is~fatal.
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Option~xoffset~forbidden }
+ {
+ You~can't~use~the~option~'xoffset'~in~the~command~
+ \l_@@_string_Arrow_for_msg_str\
+ while~you~are~using~the~option~
+ ' \int_compare:nNnTF \l_@@_pos_arrow_int = 7
+ { group }
+ { groups } '. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nnn { Duplicate~name }
+ {
+ The~name~'\l_keys_value_tl'~is~already~used~and~you~shouldn't~use~
+ the~same~environment~name~twice.~You~can~go~on,~but,~
+ maybe,~you~will~have~incorrect~results. \\
+ For~a~list~of~the~names~already~used,~type~H~<return>. \\
+ If~you~don't~want~to~see~this~message~again,~use~the~option~
+ 'allow-duplicate-names'.
+ }
+ {
+ The~names~already~defined~in~this~document~are:~
+ \seq_use:Nnnn \g_@@_names_seq { ,~ } { ,~ } { ~and~ }.
+ }
+% \end{macrocode}
+%
+%
+%
+% \subsection{The command \textbackslash WithArrowsNewStyle}
+%
+% A new key defined with |\WithArrowsNewStyle| will not be available at the
+% local level.
+% \begin{macrocode}
+%<*LaTeX>
+\NewDocumentCommand \WithArrowsNewStyle { m m }
+%</LaTeX>
+%<*plain-TeX>
+\cs_new_protected:Npn \WithArrowsNewStyle #1 #2
+%</plain-TeX>
+ {
+ \keys_if_exist:nnTF { WithArrows / Global } { #1 }
+ { \@@_error:nn { Key~already~defined } { #1 } }
+ {
+ \keys_define:nn { WithArrows / Global }
+ {
+ #1 .code:n =
+ { \keys_set_known:nn { WithArrows / WithArrowsOptions } { #2 } }
+ }
+ \seq_put_right:Nx \l_@@_options_WithArrows_seq { \tl_to_str:n { #1 } }
+ \seq_put_right:Nx \l_@@_options_DispWithArrows_seq
+ { \tl_to_str:n { #1 } }
+ \seq_put_right:Nx \l_@@_options_WithArrowsOptions_seq
+ { \tl_to_str:N { #1 } }
+% \end{macrocode}
+% We now set the options in a TeX group in order to detect if some keys in |#2|
+% are unknown. If a key is unknown, an error will be raised. However, the key
+% will, even so, be stored in the definition of key~|#1|.
+% \begin{macrocode}
+ \group_begin:
+ \msg_set:nnn { witharrows } { Unknown~option~WithArrowsOptions }
+ {
+ The~key~'\l_keys_key_tl'~can't~be~set~in~the~
+ definition~of~a~style.~You~can~go~on~for~this~time~
+ but~you~should~suppress~this~key.
+ }
+ \WithArrowsOptions { #2 }
+ \group_end:
+ }
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { Key~already~defined }
+ {
+ The~key~'#1'~is~already~defined. \\
+ If~you~go~on,~your~instruction~\token_to_str:N\WithArrowsNewStyle\
+ will~be~ignored.
+ }
+% \end{macrocode}
+%
+%
+% \subsection{The options up and down}
+%
+% The options |up| and |down| are available for individual arrows. The
+% corresponding code is given here. It is independent of the main code of the
+% extension \pkg{witharrows}.
+%
+% This code is the only part of the code of \pkg{witharrows} which uses the
+% package \pkg{varwidth} and also the Tikz library |calc|. That's why we have
+% decided not to load this package and this library. If they are not loaded, the
+% user will have an error only when using the option |up| or the option |down|.
+%
+% \medskip
+% The token list |\c_@@_tikz_code_up_tl| is the value of |tikz-code| which will
+% be used for an option |up|.
+% \begin{macrocode}
+\tl_const:Nn \c_@@_tikz_code_up_tl
+ {
+ \draw [ rounded~corners ]
+ let \p1 = (#1) ,
+ \p2 = (#2)
+ in (\p1) -- node {
+%<*LaTeX>
+ \dim_set:Nn \l_tmpa_dim { \x2 - \x1 }
+ \begin { varwidth } \l_tmpa_dim
+% \end{macrocode}
+% |\narrowragged| is a command of the package \pkg{varwidth}.
+% \begin{macrocode}
+ \narrowragged
+ #3
+ \end { varwidth }
+%</LaTeX>
+%<*plain-TeX>
+ #3
+%</plain-TeX>
+ }
+ (\x2,\y1) -- (\p2) ;
+ }
+% \end{macrocode}
+%
+%
+% \medskip
+% Idem for the option |down|.
+% \begin{macrocode}
+\tl_const:Nn \c_@@_tikz_code_down_tl
+ {
+ \draw [ rounded~corners ]
+ let \p1 = (#1) ,
+ \p2 = (#2)
+ in (\p1) -- (\x1,\y2) --
+ node {
+%<*LaTeX>
+ \dim_set:Nn \l_tmpa_dim { \x1 - \x2 }
+ \begin { varwidth } \l_tmpa_dim
+ \narrowragged
+ #3
+ \end { varwidth }
+%</LaTeX>
+%<*plain-TeX>
+ #3
+%</plain-TeX>
+ }
+ (\p2) ;
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\keys_define:nn { WithArrows / Arrow / FirstPass }
+ {
+ up .code:n = \@@_set_independent: ,
+ down .code:n = \@@_set_independent: ,
+ up .default:n = NoValue ,
+ down .default:n = NoValue
+ }
+% \end{macrocode}
+%
+% \bigskip
+% \begin{macrocode}
+\keys_define:nn { WithArrows / Arrow / SecondPass }
+ {
+ up .code:n =
+ \str_if_empty:NT \l_@@_previous_key_str
+ {
+ \str_set:Nn \l_@@_previous_key_str { up }
+%<*LaTeX>
+ \bool_if:NTF \c_@@_varwidth_loaded_bool
+ {
+%</LaTeX>
+ \cs_if_exist:cTF { tikz@library@calc@loaded }
+ {
+ \int_set:Nn \l_@@_pos_arrow_int \c_one_int
+% \end{macrocode}
+% We have to set |\l_@@_wrap_lines_bool| to |false| because, otherwise, if the
+% option |wrap_lines| is used at a higher level (global or environment), we will
+% have a special affectation to |tikz-code| that will overwrite our affectation.
+% \begin{macrocode}
+ \bool_set_false:N \l_@@_wrap_lines_bool
+ \tl_set_eq:NN \l_@@_tikz_code_tl
+ \c_@@_tikz_code_up_tl
+ }
+ { \@@_error:n { calc~not~loaded } }
+%<*LaTeX>
+ }
+ { \@@_error:n { varwidth~not~loaded } }
+%</LaTeX>
+ } ,
+ down .code:n =
+ \str_if_empty:NT \l_@@_previous_key_str
+ {
+ \str_set:Nn \l_@@_previous_key_str { down }
+%<*LaTeX>
+ \bool_if:NTF \c_@@_varwidth_loaded_bool
+ {
+%</LaTeX>
+ \cs_if_exist:cTF { tikz@library@calc@loaded }
+ {
+ \int_set:Nn \l_@@_pos_arrow_int \c_one_int
+ \bool_set_false:N \l_@@_wrap_lines_bool
+ \tl_set_eq:NN \l_@@_tikz_code_tl
+ \c_@@_tikz_code_down_tl
+ }
+ { \@@_error:n { calc~not~loaded } }
+%<*LaTeX>
+ }
+ { \@@_error:n { varwidth~not~loaded } }
+%</LaTeX>
+ }
+ }
+% \end{macrocode}
+%
+%
+%
+% \begin{macrocode}
+\seq_put_right:Nn \l_@@_options_Arrow_seq { down }
+\seq_put_right:Nn \l_@@_options_Arrow_seq { up }
+% \end{macrocode}
+%
+%
+% \begin{macrocode}
+\@@_msg_new:nn { varwidth~not~loaded }
+ {
+ You~can't~use~the~option~'\l_keys_key_tl'~because~
+ you~don't~have~loaded~the~package~'varwidth'. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+\@@_msg_new:nn { calc~not~loaded }
+ {
+ You~can't~use~the~option~'\l_keys_key_tl'~because~you~don't~have~loaded~the~
+ Tikz~library~'calc'.You~should~add~'\token_to_str:N\usetikzlibrary{calc}'~
+ ~in~the~preamble~of~your~document. \\
+ \c_@@_option_ignored_str
+ }
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*plain-TeX>
+\catcode `\@ = 12
+\ExplSyntaxOff
+%</plain-TeX>
+% \end{macrocode}
+%
+% \section{History}
+%
+% \subsection*{Changes between versions 1.0 and 1.1}
+%
+% Option for the command |\\| and option |interline|
+%
+% Compatibility with |\usetikzlibrary{babel}|
+%
+% Possibility of nested environments |{WithArrows}|
+%
+%
+% \subsection*{Changes between versions 1.1 and 1.2}
+%
+% The package \pkg{witharrows} can now be loaded without having loaded
+% previously \pkg{tikz} and the libraries |arrow.meta| and |bending| (this
+% extension and these libraries are loaded silently by \pkg{witharrows}).
+%
+% New option |groups| (with a \emph{s})
+%
+%
+% \subsection*{Changes between versions 1.2 and 1.3}
+%
+% New options |ygap| and |ystart| for fine tuning.
+%
+% \subsection*{Changes between versions 1.3 and 1.4}
+%
+% The package \pkg{footnote} is no longer loaded by default. Instead, two
+% options |footnote| and |footnotehyper| have been added. In particular,
+% \pkg{witharrows} becomes compatible with \cls{beamer}.
+%
+% \subsection*{Changes between versions 1.4 and 1.5}
+%
+% The Tikz code used to draw the arrows can be changed with the option
+% |tikz-code|.
+%
+% Two new options |code-before| and |code-after| have been added at the
+% environment level.
+%
+% A special version of |\Arrow| is available in |code-after| in order to draw
+% arrows in nested environments.
+%
+% A command |\MultiArrow| is available in |code-after| to draw arrows of other
+% shapes.
+%
+% \subsection*{Changes between versions 1.5 and 1.6}
+%
+% The code has been improved to be faster and the Tikz library |calc| is no
+% longer required.
+%
+% A new option |name| is available for the environments |{WithArrows}|.
+%
+% \subsection*{Changes between 1.6 and 1.7}
+%
+% New environments |{DispWithArrows}| and |{DispWithArrows*}|.
+%
+% \subsection*{Changes between 1.7 and 1.8}
+%
+% The numbers and tags of the environment |{DispWithArrows}| are now compatible
+% with all the major LaTeX packages concerning references (\pkg{autonum},
+% \pkg{cleveref}, \pkg{fancyref}, \pkg{hyperref}, \pkg{prettyref},
+% \pkg{refstyle}, \pkg{typedref} and \pkg{varioref}) and with the options
+% |showonlyrefs| and |showmanualtags| of \pkg{mathtools}.
+%
+% \subsection*{Changes between 1.8 and 1.9}
+%
+% New option |wrap-lines| for the environments |{DispWithArrows}| and
+% |{DispWithArrows*}|.
+%
+% \subsection*{Changes between 1.9 and 1.10}
+%
+% If the option |wrap-lines| is used, the option ``|text width|'' of Tikz is
+% still active: if the value given to ``|text width|'' is lower than the width
+% computed by |wrap-lines|, this value is used to wrap the lines.
+%
+% The option |wrap-lines| is now fully compatible with the class option |leqno|.
+%
+% Correction of a bug: |\nointerlineskip| and |\makebox[.6\linewidth]{}| should
+% be inserted in |{DispWithArrows}| only in vertical mode.
+%
+% \subsection*{Changes between 1.10 and 1.11}
+%
+% New commands |\WithArrowsNewStyle| and |\WithArrowsRightX|.
+%
+% \subsection*{Changes between 1.11 and 1.12}
+%
+% New command |\tagnextline|.
+%
+% New option |tagged-lines|.
+%
+% An option of position (|ll|, |lr|, |rl|, |rr| or |i|) is now allowed at the
+% local level even if the option |group| or the option |groups| is used at the
+% global or environment level.
+%
+% Compatibility of |{DispWithArrows}| with |\qedhere| of \pkg{amsthm}.
+%
+% Compatibility with the packages \pkg{refcheck}, \pkg{showlabels} and
+% \pkg{listlbls}.
+%
+% The option |\AllowLineWithoutAmpersand| is deprecated because lines without
+% ampersands are now always allowed.
+%
+% \subsection*{Changes between 1.12 and 1.13}
+%
+% Options |start-adjust|, |end-adjust| and |adjust|.
+%
+% This version is not stricty compatible with previous ones. To restore the
+% behaviour of the previous versions, one has to use the option |adjust| with
+% the value $0$~pt:
+%
+% \begin{Verbatim}
+% \WithArrowsOptions{adjust = 0pt}
+% \end{Verbatim}
+%
+% \subsection*{Changes between 1.13 and 1.14}
+%
+% New options |up| and |down| for the arrows.
+%
+% \smallskip
+% Replacement of some options |O { }| in commands and environments defined with
+% \pkg{xparse} by |! O { }| (a recent version of \pkg{xparse} introduced
+% the specifier |!| and modified the default behaviour of the last optional
+% arguments:
+% |//www.texdev.net/2018/04/21/xparse-optional-arguments-at-the-end|).
+%
+% \smallskip
+% Modification of the code of |\WithArrowsNewStyle| following a correction of a
+% bug in \pkg{l3keys} in the version of \pkg{l3kernel} of 2019/01/28.
+%
+% New error message |Inexistent~v-node| to avoid a \pkg{pgf} error.
+%
+% The error |Option incompatible with 'group(s)'| was suppressed in the version
+% 1.12 but this was a mistake since this error is used with the option |xoffset|
+% at the local level. The error is put back.
+%
+% \subsection*{Changes between 1.14 and 1.15}
+%
+% Option |new-group| to start a new group of arrows (only available when the
+% environment is composed with the option |groups|).
+%
+% Tikz externalization is now deactivated in the environments of the
+% extension \pkg{witharrows}.\footnote{Before this version, there was an error
+% when using \pkg{witharrows} with Tikz externalization. In any case, it's not
+% possible to externalize the Tikz elements constructed by \pkg{witharrows}
+% because they use the options |overlay| and |remember picture|.}
+%
+% \subsection*{Changes between 1.15 and 1.16}
+%
+% Option |no-arrows|
+%
+% The behaviour of |{DispWithArrows}| after an |\item| of a LaTeX list has been
+% changed : no vertical is added. The previous behaviour can be restored with
+% the option |standard-behaviour-with-items|.
+%
+% A given name can no longer be used for two distinct environments. However,
+% it's possible to deactivate this control with the option
+% |allow-duplicate-names|.
+%
+%
+% \subsection*{Changes between 1.16 and 1.17}
+%
+% Option |format|
+%
+% \subsection*{Changes between 1.17 and 1.18}
+%
+% New option |<...>| for |{DispWithArrows}|.
+%
+% Option |subequations|.
+%
+% Warning when |{WithArrows}| or |{DispWithArrows}| ends by "\\".
+%
+% No space before an environnement |{DispWithArrows}| if we are at the beginning
+% of a |{minipage}|.
+%
+% \subsection*{Changes between 1.18 and 2.0}
+%
+% A version of \pkg{witharrows} is available for plain-TeX.
+%
+% \PrintIndex
+%
+% \tableofcontents
+%
+% \endinput
+% Local Variables:
+% TeX-fold-mode: nil
+% fill-column: 80
+% End: