path: root/Master/texmf-dist/source/latex/spalign/spalign.dtx

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% Copyright (C) 2016 by Joseph Rabinoff <rabinoff@math.gatech.edu>
% -------------------------------------------------------
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% conditions of the LaTeX Project Public License, either version 1.3
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%    http://www.latex-project.org/lppl.txt
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\documentclass{ltxdoc}
\usepackage{spalign}[2016/10/05]
\usepackage[charter,sfscaled,ttscaled,cal=cmcal]{mathdesign}
\usepackage{amsmath}

\def\usage#1#2{\textbf{Usage:} \texttt{\string#1} #2\vadjust{\vskip 1ex}\\}

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  }
\def\endopt{\par\vskip2pt}

\let\tvs=\textvisiblespace

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\end{document}
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%   Acute accent  \'     Left paren    \(     Right paren   \)
%   Asterisk      \*     Plus          \+     Comma         \,
%   Minus         \-     Point         \.     Solidus       \/
%   Colon         \:     Semicolon     \;     Less than     \<
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%   Grave accent  \`     Left brace    \{     Vertical bar  \|
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% \changes{v1.0}{2016/10/05}{Initial version}
%
% \GetFileInfo{spalign.dtx}
%
% \DoNotIndex{\newcommand,\newenvironment}
%
%
% \title{The \textsf{spalign} package\thanks{This document
%   corresponds to the version of \textsf{spalign} dated \filedate.}}
% \author{Joseph Rabinoff \\ \texttt{rabinoff@math.gatech.edu}}
%
% \maketitle
%
% \section{Introduction}
%
% The purpose of this package is to decrease the number of keystrokes needed to
% typeset small amounts of aligned material (matrices, arrays, etc.).  For
% instance, it is inconvenient to type (using the \textsf{amsmath} package)
% \begin{verbatim}
%    \[ \begin{matrix}
%          1 & 12 & -3 \\
%         24 & -2 &  2 \\
%          0 &  0 &  1
%       \end{matrix} \]\end{verbatim}
% in a document where several hundred such
% matrices must  be typeset.  Of course
% one can always define a macro |\mat| which puts its argument inside a
% |matrix| environment, but it is still necessary to type the align character
% |&| and the end-of-row control sequence |\\| many times for each matrix.
%
% This package provides a facility for typesetting matrices, and using other
% alignment environments and macros, with spaces as the
% alignment delimiter and semicolons (by default) as the end-of-row indicator.  So
% the above matrix could be produced using the command:
% \begin{verbatim}
%    \[ \spalignmat{1 12 -3; 24 -2 2; 0 0 1} \]\end{verbatim}
% This package also contains utility macros for typesetting augmented matrices,
% vectors, arrays, and more, and is easily extendable to other situations that use
% alignments.
%
% \section{Usage}
%
% In~\S\ref{sec:alignment} the simplified alignment format used by arguments to
% macros in this package is described.  In~\S\ref{sec:utility} the utility
% macros provided by the \textsf{spalign} package are presented; these are the
% macros that most users will need.  Section~\ref{sec:options} contains the
% package options.  The macros designed to allow the user to adapt the
% \textsf{spalign} package to other situations are presented
% in~\S\ref{sec:general}.
%
% \subsection{Alignment format}\label{sec:alignment}
% The core functionality of the \textsf{spalign} package is to convert spaces to
% alignment characters `|&|' and semicolons to end-of-row control sequences
% `|\\|'.  This process is called \textit{retokenization}.  The retokenization
% procedure is designed to work more or less how one would expect.
% Retokenization of a string \meta{text} proceeds as follows.
% \begin{enumerate}
% \item Spaces at the beginning and end of \meta{text} are ignored, as are
%   spaces at the beginning and end of a line, and spaces before and after a
%   semicolon or a comma.
% \item Multiple spaces are combined into one space.
% \item Spaces between non-space characters are converted to |&| (really, to
%   the contents of |\spalignaligntab|).
% \item Commas (really, the contents of |\spalignseparator|) are also converted to
% |&|.
% \item Semicolons (really, the contents of |\spalignendofrow|) are
%   converted to |\\| (really, to the contents of |\spalignendline|).
% \item Text in braces |{...}| is treated as a unit: the contents are not
%   retokenized, and the braces are preserved.
% \end{enumerate}
% These rules are best understood by example.
%
% \medskip\noindent\textbf{Example.} The command
% \begin{verbatim}
%    \[ \spalignmat{ 1
%         -2 3 ; 4
%         55 2^3;
%         \frac{1 1}2 {1
%         3} {1 0 1} } \]\end{verbatim}
% produces
% \[\spalignmat{ 1
%        -2 3 ; 4
%        55 2^3 ;
%        \frac{1 1}2 {1
%        3} {1 0 1} }.
% \]
%
% \medskip\noindent\textbf{Example.} The command
% \begin{verbatim}
%    \[ \spalignmat{ \cos\theta, \sin\theta;
%       -\sin\theta, \cos\theta} \]\end{verbatim}
% produces
% \[\spalignmat{ \cos\theta, \sin\theta;
%      -\sin\theta, \cos\theta}.
% \]
% Here the commas are necessary: \TeX\ will not tokenize spaces following a
% command sequence, so
% \begin{verbatim}
%    \[ \spalignmat{ \cos\theta \sin\theta;
%       -\sin\theta \cos\theta} \]\end{verbatim}
% produces the (presumably unexpected) result
% \[\spalignmat{ \cos\theta \sin\theta;
%      -\sin\theta \cos\theta}.
% \]
% Instead of commas, one could also type, for instance,
% \begin{verbatim}
%    \[ \spalignmat{ \cos\theta{} \sin\theta;
%       -\sin{\theta} \cos\theta} \]\end{verbatim}
% 
% \medskip\noindent\textbf{Example.} The fact that expressions between braces
% |{...}| are not retokenized allows for arbitrarily complex entries in
% \textsf{spalign} macros---although these macros are probably not terribly
% useful in such cases.  The \textsf{spalign} macros can even be nested: for
% instance, 
% \begin{verbatim}
%    \[ \spalignmat{ \spalignmat{a b; c d} \spalignmat{a' b'; c' d'};
%         \spalignmat{d e; f g} \spalignmat{d' e'; f' g'} } \] \end{verbatim}
% produces
% \[ \spalignmat{ \spalignmat{a b; c d} \spalignmat{a' b'; c' d'};
%       \spalignmat{d e; f g} \spalignmat{d' e'; f' g'} }. \]
% 
%
% \subsection{Utility macros}\label{sec:utility}
% Most math-mode utility macros use the |array| environment internally.  This
% can be the vanilla \LaTeX\ |array| environment, or the one from the
% \textsf{array} package; it makes no difference.  All math-mode utility macros
% have an un-starred version and a starred version.  The un-starred version
% produces arrays with the delimiters defined by the package options
% (see~\ref{sec:options}), and the starred version omits the delimiters (and the
% glue between the delimiters and the array).
%
% As the only purpose of this package is to save keystrokes, the user may want
% to put
% \begin{verbatim}
%    \let\mat=\spalignmat
%    \let\amat=\spalignaugmat
%    \let\vec=\spalignvector\end{verbatim}
% or something similar after |\usepackage{spalign}|.  Note that |\mat*| will now
% also be synonymous with |\spalignmat*|, etc.
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignarray}
% \DescribeMacro{\spalignarray*}
% \usage\spalignarray{\marg{alignment specifier}\marg{text}}
% Produces a (potentially delimited) |array| environment, passing it
% \meta{alignment specifier}, after retokenizing \meta{text}.  This is exactly
% like the matrix environments below, except that it is possible to specify the
% alignment of each column separately, add vertical bars, etc.
% For example,
% \begin{verbatim}
%    \[ \spalignarray{l|c|r}{1 1 1; 100 100 100} \]\end{verbatim}
% produces
% \[ \DeleteShortVerb{\|}
%    \spalignarray{l|c|r}{1 1 1; 100 100 100}. 
%    \MakeShortVerb{\|}
% \]
% Note that |\spalignarray*| simply produces an |array| environment surrounding
% the retokenized \meta{text}.
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignmat}
% \DescribeMacro{\spalignmat*}
% \usage\spalignmat{\oarg{column alignment}\marg{text}}
% Produces a matrix whose columns are aligned according to the
% \meta{column alignment}, after retokenizing \meta{text}.  The \meta{column alignment}
% is an array environment alignment specifier for a single column (usually |l|,
% |c|, or |r|), which is used for each column.  The default is |c|.  For example,
% \begin{verbatim}
%    \[ \spalignmat[l]{1 1 1; 100 100 100} \]\end{verbatim}
% produces
% \[ \spalignmat[l]{1 1 1; 100 100 100}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignvector}
% \DescribeMacro{\spalignvector*}
% \usage\spalignvector{\oarg{column alignment}\marg{text}}
% Produces a matrix with one column.  Spaces, commas, and semicolons are all
% retokenized to the end-of-row control sequence `|\\|'.  The
% \meta{column alignment} is interpreted as in |\spalignmat|; the default is
% |c|.  For example,
% \begin{verbatim}
%    \[ \spalignvector[r]{1 100 1000} \]\end{verbatim}
% produces
% \[ \spalignvector[r]{1 100 1000}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignaugmatn}
% \DescribeMacro{\spalignaugmatn*}
% \usage\spalignaugmatn{\oarg{column alignment}\marg{augmented columns}\marg{text}}
% Produces a matrix with a vertical divider located \meta{augmented columns} from the
% right side of the matrix.  The \meta{column alignment} is interpreted as in
% |\spalignmat|; the default is |r|.  For example,
% \begin{verbatim}
%    \[ \spalignaugmatn[c]{3}{1 2 3 4; 10 20 30 40} \]\end{verbatim}
% produces
% \[ \spalignaugmatn[c]{3}{1 2 3 4; 10 20 30 40}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignaugmat}
% \DescribeMacro{\spalignaugmat*}
% \usage\spalignaugmat{\oarg{column alignment}\marg{text}}
% This is the same as |\spalignaugmatn|, with \meta{augmented columns} equal to
% $1$.  For example,
% \begin{verbatim}
%    \[ \spalignaugmat{1 2 3 4; 10 20 30 40} \]\end{verbatim}
% produces
% \[ \spalignaugmat{1 2 3 4; 10 20 30 40}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignaugmathalf}
% \DescribeMacro{\spalignaugmathalf*}
% \usage\spalignaugmathalf{\oarg{column alignment}\marg{text}}
% This is the same as |\spalignaugmatn|, with \meta{augmented columns} equal to
% the largest integer less or equal to half of the total number of columns
% parsed from \meta{text}.  For example,
% \begin{verbatim}
%    \[ \spalignaugmathalf[l]{1 2 3 4; 10 20 30 40} \]\end{verbatim}
% produces
% \[ \spalignaugmathalf[l]{1 2 3 4; 10 20 30 40}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignsys}
% \DescribeMacro{\spalignsys*}
% \usage\spalignsys{\marg{text}}
% Typesets systems of simple equations so that binary operators and relations
% are aligned vertically, and variables are right-justified.  This macro assumes
% that variables are in odd columns and that binary operators and relations are
% in even columns.  For example,
% \begin{verbatim}
%    \[ \spalignsys{2x + y = 4; x - 3y = -17} \]\end{verbatim}
% produces
% \[ \spalignsys{2x + y = 4; x - 3y = -17\rlap.} \]
% Within \marg{text} the macro |\+| is defined to be an empty box with the size
% and spacing of a binary operator, the macro |\=| is defined to be an empty box
% with the size and spacing of a relation, and the macro |\.| is defined to be
% empty.  (Ordinarily, the latter two macros produce th\=ese acc\.ents, but they
% cannot be used in math mode.)  This allows one to deal with empty columns in
% an easy-to-read way: for example,
% \begin{verbatim}
%    \[ \spalignsys{
%         2x \+ \. - 3z =  1; 
%         \. \+ 4y +  z = -4}
%    \]\end{verbatim}
% produces
%    \[ \spalignsys{
%         2x \+ \. - 3z = 1; 
%         \. \+ 4y +  z = -4\rlap.} 
%    \]
% As with the matrix macros, delimiters can be changed with the package options.
%
% \bigskip
% \noindent
% \DescribeMacro{\spaligntabular}
% \usage\spaligntabular{\marg{alignment specifier}\marg{text}}
% Produces an (undelimited) |tabular| environment, passing it
% \meta{alignment specifier}, after retokenizing \meta{text}.  This macro may be
% used outside of math mode, and therefore is undelimited.
% For example,
% \begin{verbatim}
%    \spaligntabular{lrc}{a b c; aa bb cc}\end{verbatim}
% produces
% \[ \spaligntabular{lcr}{a b c; aa bb cc} \]
%
% \subsection{Package options}\label{sec:options}
% The following package options can be specified as key-value pairs when the
% package is loaded, as in
% \begin{verbatim}
%    \usepackage[sep={,},endofrow=;]{spalign} \end{verbatim}
% They can also be set directly with macros, which are described as well.
%
% \bigskip
% \noindent
% \DescribeMacro{delims}
% \DescribeMacro{\spaligndelims}
% \poption Use: Specifies the delimiters used by all matrix macros.\endopt
% \poption Format: Must contain exactly two delimiter tokens, the first for the left
%   delimiter, the second for the right.\endopt
% \poption Default: |delims=()|\endopt
% \poption Macro: |\spaligndelims|\marg{left-delim}\marg{right-delim}\endopt
% \smallskip
% It is easier to specify |\{\}| as delimiters using the macro form.
% For example,
% \begin{verbatim}
%    \[ \spaligndelims\vert\vert \spalignmat{a b; c d} \]\end{verbatim}
% produces
% \[ \spaligndelims\vert\vert \spalignmat{a b; c d}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{sysdelims}
% \DescribeMacro{\spalignsysdelims}
% These function the same way as |delims| and |\spaligndelims|, except they
% apply only to the |\spalignsys| macro.  The default is |\spalignsysdelims\{.|,
% i.e., left brace and no right delimiter.
%
% \bigskip
% \noindent
% \DescribeMacro{matdelimskip}
% \DescribeMacro{\spalignmatdelimskip}
% \poption Use: Specifies the glue to insert between delimiters and the internal
%   |array| environment in (un-starred) math-mode matrix macros, i.e., all
%   math-mode utility macros except |\spalignvector|.\endopt
% \poption Format: Should either be empty, or expand to a legal |\hskip|,
%   |\mskip|, or |\kern| command.  (Really any sequence of tokens can be
%   specified; they will dutifully be inserted between the delimiters and the
%   |array|, but this behavior may change in future versions.)\endopt
% \poption Default: |matdelimskip=\,|\endopt
% \poption Macro: |\def\spalignmatdelimskip|\marg{skip}\endopt
% \smallskip
% Actually, an additional skip of |\hskip-\arraycolsep| is always added; the
% effect is that if |matdimskip| is empty, then there is no extra space between
% the outer columns of the |array| and the delimiters.  This is how the
% \textsf{amsmath} package's |matrix| environment is defined.  It is this
% package author's opinion that matrices look better when a thin space is added
% between the outer columns of the |array| and the delimiters.  To keep the
% original array spacing inside the delimiters, specify
% |matdelimskip=\hskip\arraycolsep|.
%
% Here are four matrices typeset, respectively, with |matdelimskip|
% set to |{}|, |\,|, |\;|, and |{\hskip\arraycolsep}|.
% \[ \def\spalignmatdelimskip{}   \spalignmat{10 20; 30 40} \quad
%    \def\spalignmatdelimskip{\,} \spalignmat{10 20; 30 40} \quad
%    \def\spalignmatdelimskip{\;} \spalignmat{10 20; 30 40} \quad
%    \def\spalignmatdelimskip{\hskip\arraycolsep} \spalignmat{10 20; 30 40}
%  \]
%
% \bigskip
% \noindent
% \DescribeMacro{vecdelimskip}
% \DescribeMacro{\spalignvecdelimskip}
% These function the same way as |matdelimskip| and |\spalignmatdelimskip|,
% except they apply only to the |\spalignvector| macro.  The default is no extra
% skip in vectors, i.e., |vecdelimskip={}|.
%
% \bigskip
% \noindent
% \DescribeMacro{sysdelimskip}
% \DescribeMacro{\spalignsysdelimskip}
% These function the same way as |matdelimskip| and |\spalignmatdelimskip|,
% except they apply only to the |\spalignsys| macro.  The default is
% |sysdelimskip=\,|.
%
% Actually there is a slight difference: the |\halign| primitive used in the
% |\spalignsys| macro does not put glue on the outsides of the columns, so that
% it is unnecessary to subtract any |\arraycolsep| glue.
%
% \bigskip
% \noindent
% \DescribeMacro{systabspace}
% \DescribeMacro{\spalignsystabspace}
% \poption Use: Specifies the amount of glue between columns in
%   |\spsysalign|.\endopt 
% \poption Format: Must be a legal glue specification.\endopt
% \poption Default: |systabspace=1pt|\endopt
% \poption Macro: |\spalignsystabspace=|\meta{glue}\endopt
% \smallskip
% Equations with operators, relations, and variables all aligned look a 
% better with a bit of extra spacing between these three.  Setting |systabspace|
% to zero will cause the equations to use their natural spacing, subject to
% the alignment. For example, the following systems of equations were typeset,
% respectively, with |systabspace| set to |0pt|, |1pt|, and |5pt|.
%   \[ 
%      \spalignsystabspace=0pt \spalignsys{2x + y = 4; x - 3y = -17} \qquad
%      \spalignsystabspace=1pt \spalignsys{2x + y = 4; x - 3y = -17} \qquad
%      \spalignsystabspace=5pt \spalignsys{2x + y = 4; x - 3y = -17\rlap.}
%   \]
%
% \bigskip
% \noindent
% \DescribeMacro{endofrow}
% \DescribeMacro{\spalignendofrow}
% \poption Use: Specifies the token to convert into the end-of-row
%   control sequence |\\| (really into the contents of |\spalignendline|) during
%   retokenization.\endopt
% \poption Format: Must consist of a single token.\endopt
% \poption Default: |endofrow=;|\endopt
% \poption Macro: |\def\spalignendofrow|\marg{token}\endopt
% \smallskip
% For example,
% \begin{verbatim}
%   \[ \def\spalignendofrow{|} 
%      \spalignmat{1;2 3;4 | 5;6 7;8} \]\end{verbatim}
% produces
% \[ \def\spalignendofrow{|} \spalignmat{1;2 3;4 | 5;6 7;8}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{separator}
% \DescribeMacro{\spalignseparator}
% \poption Use: Specifies a token (in addition to space tokens) to convert into
%   the alignment character `|&|' (really the contents of |\spalignseparator|)
%   during  retokenization.\endopt
% \poption Format: Must consist of a single token.\endopt
% \poption Default: |separator={,}|\endopt
% \poption Macro: |\def\spalignseparator|\marg{token}\endopt
% \smallskip
% For example,
% \begin{verbatim}
%   \[ \def\spalignseparator{|} 
%      \spalignmat{(1,2)|(3,4);(5,6)|(7,8)} \]\end{verbatim}
% produces
%   \[ \def\spalignseparator{|} \spalignmat{(1,2)|(3,4);(5,6)|(7,8)}. \]
%
% \bigskip
% The following commands can be redefined to affect the behavior of the package,
% but cannot be specified as key-value pairs when the package is loaded.
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignendline}
% \poption Use: The end-of-row token is replaced by the top-level expansion of
%   this macro during retokenization.\endopt
% \poption Format: May contain any tokens.\endopt
% \poption Default: |\def\spalignendline{\\}|\endopt
% \smallskip
% This is useful, for instance, when using \textsf{spalign} in conjunction with
% plain \TeX-style alignment macros that use |\cr| as the end-of-row token.
% See the documentation for |\spalignrun| in~\S\ref{sec:general} and the
% implementation of |\spalignsys| for examples.
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignaligntab}
% \poption Use: Spaces and the contents of |\spalignseparator| are replaced by the
%   top-level expansion of this macro during retokenization.\endopt
% \poption Format: May contain any tokens.\endopt
% \poption Default: |\def\spalignaligntab{&}|\endopt
% \smallskip
% This is useful, for instance, in one-column alignments.  For example,
% \begin{verbatim}
%   \[ \def\spalignaligntab{\\} \spalignmat{12 1 2 13} \]\end{verbatim}
% produces
%   \[ \def\spalignaligntab{\\} \spalignmat{12 1 2 13}. \]
% The |\spalignvector| macro is defined in this way.
%
%
% \subsection{General macros}\label{sec:general}
% The following macros are meant to make it easy to make new utility macros
% in different situations using \textsf{spalign}.
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignretokenize}
% \usage\spalignretokenize{\marg{text}}
% Applies the retokenization procedure to \meta{text}, and expands to the
% retokenized version.  For instance, |\spalignretokenize{1 2; 3 4}| expands to
% |1&2\\3&4|.  
% For example, using the |split| environment from the
% \textsf{amsmath} package,
% \begin{verbatim}
%    \[ \begin{split}
%         \spalignretokenize{f_0 =1; f_1 =1; f_{n+2} =f_n+f_{n+1}}
%       \end{split} \]\end{verbatim}
% produces
%    \[ \begin{split}
%         \spalignretokenize{f_0 =1; f_1 =1; f_{n+2} =f_n+f_{n+1}}.
%       \end{split} \]
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignrun}
% \usage\spalignrun{\marg{tokens}\marg{text}}
% Applies the retokenization procedure to \meta{text}, saving the result into
% the token register |\spaligntoks| (see below).  Then executes \meta{tokens},
% which presumably makes reference to |\spaligntoks|.  For example,
% \begin{verbatim}
%    \[ \def\spalignendline{\cr}
%       \spalignrun{\bordermatrix{\the\spaligntoks}}
%           {, x y; u 1 2; v 3 4} \]\end{verbatim}
% produces
%    \[ \def\spalignendline{\cr}
%       \spalignrun{\bordermatrix{\the\spaligntoks}}
%           {, x y; u 1 2; v 3 4}. \]
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignenv}
% \usage\spalignenv{\marg{before-tokens}\marg{after-tokens}\marg{text}}
% Convenience macro that expands to 
% \[ \hbox{|\spalignrun{|\meta{before-tokens}
%    |\the\spaligntoks| \meta{after-tokens}|}{|\meta{text}|}|.} \]
% For example, using the |align*| environment from the
% \textsf{amsmath} package,
% \begin{verbatim}
%    \spalignenv{\begin{align*}}{\end{align*}}%
%      {x =y x' =y'; z =w z' =w'.}\end{verbatim} 
% produces
%    \spalignenv{\begin{align*}}{\end{align*}}%
%      {x =y x' =y'; z =w z' =w'.} 
%
% \bigskip
% The \meta{tokens} arguments of |\spalignrun| and |\spalignenv| have access to
% the following registers, which are defined locally in a group inside
% |\spalignrun| and |\spalignenv|.
%
% \bigskip
% \noindent
% \DescribeMacro{\spaligntoks}
% A tokens register that contains the result of the retokenizing procedure.
%
% \bigskip
% \noindent
% \DescribeMacro{\spalignmaxcols}
% A count register that contains the maximum number of columns in any given row,
% as parsed by the retokenizer.  This is used in |\spalignmat| and in the
% |\spalignaugmat| family of macros.

% \StopEventually{}
%
% \section{Implementation}
% 
% \subsection{Options processing}
%
%    \begin{macrocode}
\makeatletter

\RequirePackage{kvoptions}
%    \end{macrocode}
% With the following options, the key |foo| gets stored as |\spalign@foo|.
%    \smallskip
%    \begin{macrocode}
\SetupKeyvalOptions{family=spalign,prefix=spalign@}

\DeclareStringOption[()]{delims}
\DeclareStringOption[\{.]{sysdelims}
\DeclareStringOption[\,]{matdelimskip}
\DeclareStringOption[]{vecdelimskip}
\DeclareStringOption[\,]{sysdelimskip}
\DeclareStringOption[1pt]{systabspace}
\DeclareStringOption[;]{endofrow}
\DeclareStringOption[,]{separator}

\ProcessLocalKeyvalOptions*

\def\spaligndelims#1#2{%
  \def\spalign@leftdelim{#1}\def\spalign@rightdelim{#2}}
\expandafter\spaligndelims\spalign@delims
\def\spalignsysdelims#1#2{%
  \def\spalign@sysleftdelim{#1}\def\spalign@sysrightdelim{#2}}
\expandafter\spalignsysdelims\spalign@sysdelims
\let\spalignmatdelimskip=\spalign@matdelimskip
\let\spalignvecdelimskip=\spalign@vecdelimskip
\let\spalignsysdelimskip=\spalign@sysdelimskip
\newdimen\spalignsystabspace
\spalignsystabspace=\spalign@systabspace
\let\spalignendofrow=\spalign@endofrow
\let\spalignseparator=\spalign@separator
\def\spalignendline{\\}
\def\spalignaligntab{&}
%    \end{macrocode}
%
% \bigskip
% \subsection{Main retokenizing code}
% The retokenizer processes the input token list one ``item'' at a time,
% performing replacements as necessary, and saving the resulting tokens in
% |\spaligntoks|.  The difficulties arise because of the special treatment that
% \TeX\ gives to spaces and braces.  First let's review the rules of the game:
% \begin{enumerate}\itemsep=1\jot\parskip=0pt
% \item Spaces after a control sequence are not tokenized.
% \item Multiple spaces are tokenized into a single space.
% \item Space tokens between a control sequence and its argument are ignored:
%   undelimited spaces are never interpreted as a macro argument.
% \item Braces around a macro argument are stripped.
% \item The |\futurelet|\meta{control sequence}\meta{token1}\meta{token2} syntax
%   will |\let| the specified \meta{control sequence} be \meta{token2}, nomatter
%   what kind of token \meta{token2} is.
% \end{enumerate}
% Consider then a macro |\retokenize#1{...}| and the token sequence
% \[ \hbox{|\retokenize |\tvs|{\bf a}b|} \]
% The |\retokenize| macro needs to recognize both the space (as it should be
% replaced by an align token, if other non-space tokens have just been processed),
% and the braces (so |{\bf a}b| is not replaced by |\bf ab|).  However, the
% argument to |\retokenize| will be |\bf a|; the space and braces are ignored.
%
% The solution, of course, is judicious use of |\futurelet|.  (One could
% conceivably use |\let| and |\futurelet| exclusively, except then one would
% have the opposite problem: we \emph{want} the retokenizer to swallow whole
% arguments in braces.)  This is still somewhat tricky:
% \[ \hbox{|\futurelet\next\retokenize |\tvs|{\bf a}b|} \]
% will expand |\retokenize| with the argument set to |\bf a| and |\next|
% behaving like \tvs, but the braces will still disappear.  Hence one has to use
% the |\futurelet| in a macro which does not take any arguments.
%
% Here is the outline of the solution to the problem used in this package.  The
% |\spalign@gobble@spaces| macro has the effect of deleting the subsequent
% sequence of space tokens and replacing them with the token
% |\spalign@parsetoks|.  It sets |\spalign@saw@spacetrue| if it ate at least
% one space token, and in any case it sets |\spalign@nexttok| to the following
% token.  The |\spalign@parsetoks| macro takes one argument.  When it is
% executed, |\spalign@nexttok| represents a non-space token.  Now
% |\spalign@parsetoks| knows if the token beginning its argument is a brace, and
% it knows if there was a space preceding the brace as well, using
% |\ifspalign@saw@space|.  It can proceed to parse its argument in a
% straightforward manner, eventually expanding back into
% |\splign@gobble@spaces|, unless it sees |\spalign@end|, which signifies the
% end of input.
%
% See Appendix~D in the {\TeX}book for a discussion of these kinds of tricks.
%
% \begin{macro}{\spalign@makespace}
%   This macro expands to a single space token.  It is mildly tricky to
%   construct, since \TeX\ allows one optional space token after |\let\foo| or
%   |\let\foo=|, but multiple spaces are combined into one space token.  Here is
%   one trick for producing two consecutive space tokens.  See Exercise~24.6 in
%   the {\TeX}book.
%    \begin{macrocode}
\begingroup
\def\\{\global\let\spalign@space= } \\ %
\endgroup
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@end}
%   Sentinel macro that is used to mark the end-of-input for
%   |\spalign@parsetoks|.  Defining it recursively like this has the
%   disadvantage that \LaTeX\ will hang if it tries to expand |\spalign@end|.
%   On the other hand, one can test whether a token is |\spalign@end| using
%   |\ifx| without using some other sentinel expansion of the macro, and the
%   only reason |\spalign@end| would be executed is if there is a bug in this
%   package. 
%    \begin{macrocode}
\def\spalign@end{\spalign@end}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@bgroup}
%   This is just used to test whether a token is a literal |\bgroup| (as opposed
%   to an actual open brace |{|) using |\ifx|.
%    \begin{macrocode}
\def\spalign@bgroup{\bgroup}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@curcols}
%   This counter keeps track of how many columns are in the current row.
%    \begin{macrocode}
\newcount\spalign@curcols
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ifspalign@ignorespaces}
%   Boolean variable which keeps track of whether spaces should be ignored in
%   the current state, like after an end-of-row token.
%    \begin{macrocode}
\newif\ifspalign@ignorespaces
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ifspalign@saw@space}
%   Boolean variable which is true if the argument to |\spalign@parsetoks| was
%   preceded by at least one space token.
%    \begin{macrocode}
\newif\ifspalign@saw@space
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@gobble@spaces}
%   This macro has the effect of deleting any subsequent space tokens, replacing
%   them with |\spalign@parsetoks|.  It sets |\spalign@nexttok| to the next
%   (non-space) token, and sets |\spalign@saw@spacetrue| if it ate at least one
%   space.  The boolean variable |\ifspalign@saw@space| should be false before
%   |\spalign@gobble@spaces| is first executed.
%
%   The macro |\spalign@gobble@next| has the effect of replacing the following
%   token with |\spalign@gobble@spaces|.
%    \begin{macrocode}
\def\spalign@gobble@next{%
  \afterassignment\spalign@gobble@spaces\let\spalign@atoken= }
\def\spalign@check@space{%
  \ifx\spalign@nexttok\spalign@space%
    \spalign@saw@spacetrue%
    \let\spalign@next=\spalign@gobble@next%
  \else%
%    \end{macrocode}
%   Don't set |\spalign@saw@spacefalse| here: eventually we will run
%   into a non-space token.
%    \begin{macrocode}
    \let\spalign@next=\spalign@parsetoks%
  \fi%
  \spalign@next%
  }
\def\spalign@gobble@spaces{%
  \futurelet\spalign@nexttok\spalign@check@space}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@append}
%   Convenience macro that appends its argument, unexpanded, onto the token
%   register |\spaligntoks|.
%    \begin{macrocode}
\def\spalign@append#1{%
  \begingroup%
  \toks255={#1}%
%    \end{macrocode}
%   The |\edef| and |\xdef| macros do not expand tokens obtained by expanding a
%   token register.
%    \begin{macrocode}
  \xdef\spalign@settok{%
    \spaligntoks={\the\spaligntoks\the\toks255}}%
  \endgroup%
  \spalign@settok%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@addcol}
%   Convenience macro to take care of housekeeping when an align column has been
%   parsed but the row is not complete.  Note that it appends the top-level
%   expansion of |\spaligntab| to |\spaligntoks|, not the token |\spaligntab|
%   itself.
%    \begin{macrocode}
\def\spalign@addcol{%
  \expandafter\spalign@append\expandafter{\spalignaligntab}%
  \advance\spalign@curcols by 1 %
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@endrow}
%   Convenience macro to take care of housekeeping when a row has been ended,
%   either by an end-of-row token or an end-of-input token.
%    \begin{macrocode}
\def\spalign@endrow{%
  \advance\spalign@curcols by 1 %
  \ifnum\spalign@curcols>\spalignmaxcols%
    \spalignmaxcols=\spalign@curcols%
  \fi%
  \spalign@curcols=0%
  \spalign@ignorespacestrue%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@normaltok}
%   Convenience macro to take care of housekeeping when a non-special token (not
%   a space, end-of-row token, separator token, or end-of-input token) has been
%   parsed.  The boolean variable |\ifspalign@saw@space| will be true if the token
%   preceding the non-special token was a space.
%    \begin{macrocode}
\def\spalign@normaltok{%
  \ifspalign@saw@space%
    \ifspalign@ignorespaces%
    \else%
      \spalign@addcol%
    \fi%
  \fi%
  \spalign@ignorespacesfalse%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@parsetoks}
%   This is the main retokenizing routine.  It is only called by
%   |\spalign@gobble@spaces|.  When it is expanded, |\spalign@nexttok| is the
%   token that immediately follows the |\spalign@parsetoks| token itself; this
%   is not a space.  The value of the boolean variable |\ifspalign@saw@space| is
%   true if there was a space before the argument of |\spalign@parsetoks| in the
%   token list.
%    \begin{macrocode}
\def\spalign@parsetoks#1{%
  \let\spalign@next=\spalign@gobble@spaces%
%    \end{macrocode}
%   This is for |\ifx| comparisons:
%    \begin{macrocode}
  \def\spalign@arg{#1}%
%    \end{macrocode}
%   Anything in braces is passed through untouched:
%    \begin{macrocode}
  \ifx\spalign@nexttok\bgroup%
    \spalign@normaltok%
    \ifx\spalign@arg\spalign@bgroup%
%    \end{macrocode}
%   The argument is a literal |\bgroup|, not a brace.
%    \begin{macrocode}
      \spalign@append{#1}%
    \else%
%    \end{macrocode}
%   Re-wrap the argument in braces and append.
%    \begin{macrocode}
      \spalign@append{{#1}}%
    \fi%
  \else%
%    \end{macrocode}
%   The argument is not wrapped in braces.
%    \begin{macrocode}
    \ifx\spalign@arg\spalignendofrow%
%    \end{macrocode}
%   End-of-row token.  Append the top-level expansion of |\spalignendline|.
%   (Ignore previous spaces.)
%    \begin{macrocode}
      \expandafter\spalign@append\expandafter{\spalignendline}%
      \spalign@endrow%
    \else%
      \ifx\spalign@arg\spalignseparator%
%    \end{macrocode}
%   Separator token.  (Ignore previous spaces.)
%    \begin{macrocode}
        \spalign@addcol%
        \spalign@ignorespacestrue%
      \else%
        \ifx\spalign@arg\spalign@end%
%    \end{macrocode}
%   End-of-input token.  End the current row to record |\spalign@maxcols|.
%   (Ignore previous spaces.)
%    \begin{macrocode}
          \let\spalign@next=\relax%
          \spalign@endrow%
        \else%
%    \end{macrocode}
%   Non-special token.
%    \begin{macrocode}
          \spalign@normaltok%
          \spalign@append{#1}%
        \fi%
      \fi%
    \fi%
  \fi%
%    \end{macrocode}
%   Reset |\ifspalign@saw@space| for the next |\spalign@gobble@spaces|.
%    \begin{macrocode}
  \spalign@saw@spacefalse%
  \spalign@next%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@process}
%   This is a wrapper for |\spalign@parsetoks|.  It initializes registers and
%   boolean variables, then starts the parsing routine with
%   |\spalign@gobble@spaces|.  It should be run in a local group.  It stops
%   processing at |\spalign@end|.  It fills |\spalignmaxcols| and |\spaligntoks|
%   with the results of the retokenization.  It replaces everything in the token
%   list up through |\spalign@end| with |\relax|.
%    \begin{macrocode}
\def\spalign@process{%
  \spaligntoks={}%
  \spalignmaxcols=0%
  \spalign@curcols=0%
  \spalign@ignorespacestrue%
  \spalign@saw@spacefalse%
  \spalign@gobble@spaces%
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{Poor man's starred commands}
% There are several excellent packages that allow for flexible command
% specifications.  However, the needs of this package are minimal as regards
% starred commands, so in order to reduce dependencies, this package contains
% its own simple implimentation.
%
% \begin{macro}{\ifspalign@star}
%   Boolean variable which records whether or not the current command has a star
%   on it.
%    \begin{macrocode}
\newif\ifspalign@star
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@def@star}
%   Used like |\def|, the command |\spalign@def@star\foo{...}| defines a macro
%   |\foo| which can be called as |\foo| or |\foo*|.  In the body of |\foo|,
%   the boolean variable |\ifspalign@star| indicates whether the command was
%   called with a star.
%
%   This command actually defines three commands: |\foo|, |\foo@x|, and
%   |\foo@star|.  The first calls the second with |\spalign@nexttok| defined via
%   |\futurelet| to the token following |\foo|.  The command |\foo@x| checks
%   whether or not the next token is a star, and if it is, it is removed from
%   the token list.  It then sets |\ifspalign@star| appropriately and calls
%   |\foo@star|, which contains the original command definition.  Of course,
%   |\foo@star| can then be redefined, for instance using |\newcommand|, to take
%   advantage of \LaTeX's optional argument parsing.
%    \begin{macrocode}
\def\spalign@gobble@one#1{}

\def\spalign@def@star#1{%
%    \end{macrocode}
%   If |#1| is |\foo|, then |\spalign@cmd| expands to |\foo|,
%   |\spalign@cmd@x| expands to |\foo@x|, and |\spalign@cmd@star| expands to
%   |\foo@star|.
%    \begin{macrocode}
  \def\spalign@cmd{#1}%
  \edef\spalign@cmd@x{%
    \csname\expandafter\spalign@gobble@one\string#1@x\endcsname}%
  \edef\spalign@cmd@star{%
    \csname\expandafter\spalign@gobble@one\string#1@star\endcsname}%
%    \end{macrocode}
%   Make |\foo@x| unexpandable.  (The |\csname...\endcsname| construction
%   already does this, but only if |\foo@x| was previously undefined.)  This
%   makes it easier to define |\foo|.
%    \begin{macrocode}
  \expandafter\let\spalign@cmd@x=\relax
  \expandafter\edef\spalign@cmd{%
    \futurelet\noexpand\spalign@nexttok\spalign@cmd@x}%
%    \end{macrocode}
%   I don't know a less annoying but still short way of defining a token list
%   where only one token in the middle is to be expanded, and that one token only
%   once (not recursively).
%    \begin{macrocode}
  \def\spalign@mkcmd##1{%
    \expandafter\def\spalign@cmd@x{%
      \ifx\spalign@nexttok*%
        \spalign@startrue%
        \let\spalign@next=\spalign@gobble@one%
      \else%
        \spalign@starfalse%
        \def\spalign@next{}%
      \fi%
%    \end{macrocode}
%   Expanding |\spalign@gobble@one| before |##1| (which is |\foo@star|) eats the
%   star before parsing the arguments for |\foo@star|.
%    \begin{macrocode}
      \expandafter##1\spalign@next%
      }%
    }%
  \expandafter\spalign@mkcmd\spalign@cmd@star%
  \expandafter\def\spalign@cmd@star%
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{General macros}
%
% Here are the definitions of the macros presented in~\S\ref{sec:general}.
%    \begin{macrocode}
\newtoks\spaligntoks
\newcount\spalignmaxcols
%    \end{macrocode}
% \begin{macro}{\spalignrun}
%   Calls |\spalign@process| on |#2|, then inserts |#1|, in a group.
%   Presumably |#1| will refer to |\spaligntoks| and/or |\spalignmaxcols|.
%    \begin{macrocode}
\def\spalignrun#1#2{%
  \begingroup%
  \spalign@process#2\spalign@end%
  %\showthe\spaligntoks%  For debugging
  #1%
  \endgroup%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignenv}
%   This effectively calls |\spalign@process| on |#3|, then puts the resulting
%   token list between |#1| and |#2|.  Both |#1| and |#2| have access to
%   |\spaligntoks| and |\spalignmaxcols|.
%    \begin{macrocode}
\def\spalignenv#1#2{%
  \spalignrun{%
    #1%
    \the\spaligntoks%
    #2%
    }%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignretokenize}
%   This calls |\spalign@process| on |#1|, then expands to |\the\spaligntoks|.
%    \begin{macrocode}
\def\spalignretokenize#1{%
  \begingroup%
  \spalign@process#1\spalign@end%
  \expandafter\endgroup\the\spaligntoks%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spaligntabular}
%   Tabular utility macro.
%    \begin{macrocode}
\def\spaligntabular#1#2{%
  \begin{tabular}{#1}\spalignretokenize{#2}\end{tabular}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@maybedelim}
%   This is like |\spalignenv|, but it adds delimiters and the glue specified in
%   |#3| before |#1| and after |#2|, if |\ifspalign@star| is false.
%    \begin{macrocode}
\def\spalign@maybedelim#1#2#3{%
  \spalignenv%
    {\ifspalign@star\else\left\spalign@leftdelim#3\fi#1}%
    {#2\ifspalign@star\else#3\right\spalign@rightdelim\fi}%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignarray}
%   Array utility macro with delimiters.
%    \begin{macrocode}
\spalign@def@star\spalignarray#1{%
  \spalign@maybedelim%
    {\begin{array}{#1}}%
    {\end{array}}%
    {\hskip-\arraycolsep\spalignmatdelimskip}%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignvector}
%   Vector utility macro: an array with one column, with |\spaligntab| set to
%   |\\| so that spaces produce new rows.
%    \begin{macrocode}
\spalign@def@star\spalignvector{}
\renewcommand\spalignvector@star[2][c]{%
  \begingroup%
  \def\spalignaligntab{\\}%
  \spalign@maybedelim%
    {\begin{array}{#1}}%
    {\end{array}}%
%    \end{macrocode}
%   Note the use of |\spalignvecdelimskip| here.
%    \begin{macrocode}
    {\hskip-\arraycolsep\spalignvecdelimskip}%
    {#2}%
  \endgroup%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalign@repeat}
%   Sets |\spalign@repeated| to |#1|, repeated |#2| times.  Used for
%   auto-constructing |array| alignment specifications from |\spalignmaxcols|.
%    \begin{macrocode}
\def\spalign@repeat#1#2{%
  \begingroup%
  \count255=0 %
  \toks255={}%
  \loop\ifnum\count255<#2%
    \edef\spalign@settok{\toks255={\the\toks255 #1}}%
    \spalign@settok%
    \advance\count255 by 1 %
  \repeat%
  \xdef\spalign@repeated{\the\toks255}%
  \endgroup
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignmat}
%   Matrix utility macro.  Uses |\spalignmaxcols| and |\spalign@repeat| to
%   construct the |array| align specification.
%    \begin{macrocode}
\spalign@def@star\spalignmat{}
\renewcommand\spalignmat@star[1][c]{%
  \spalign@maybedelim{%
    \spalign@repeat{#1}{\spalignmaxcols}%
    \edef\spalign@barray{\noexpand\begin{array}{%
        \spalign@repeated}}%
    \spalign@barray%
    }{\end{array}%
    }{\hskip-\arraycolsep\spalignmatdelimskip}%
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignaugmatn}
%   Augmented matrix with |#2| columns on the right of the vertical bar.  Uses
%   |\spalignmaxcols| and |\spalign@repeat| to construct the |array| align
%   specification.
%    \begin{macrocode}
\spalign@def@star\spalignaugmatn{}
\renewcommand\spalignaugmatn@star[2][r]{%
  \spalign@maybedelim{%
    \advance\spalignmaxcols by -#2 %
    \spalign@repeat{#1}{\spalignmaxcols}%
    \let\spalign@repeated@one=\spalign@repeated%
    \spalign@repeat{#1}{#2}%
    \let\spalign@repeated@two=\spalign@repeated%
    \edef\spalign@barray{\noexpand\begin{array}{%
        \spalign@repeated@one|\spalign@repeated@two}}%
    \spalign@barray%
    }{\end{array}%
    }{\hskip-\arraycolsep\spalignmatdelimskip}%
  }%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignaugmat}
%   Augmented matrix with one column on the right of the vertical bar.
%    \begin{macrocode}
\spalign@def@star\spalignaugmat{}
\renewcommand\spalignaugmat@star[1][r]{%
  \spalignaugmatn@star[#1]{1}%
  }%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignaugmathalf}
%   Augmented matrix with (ceiling of) half the columns on the right.
%    \begin{macrocode}
\spalign@def@star\spalignaugmathalf{}
\renewcommand\spalignaugmathalf@star[1][r]{%
  \spalign@maybedelim{%
    \count255=\spalignmaxcols%
    \divide\spalignmaxcols by 2 %
    \advance\count255 by -\spalignmaxcols%
    \spalign@repeat{#1}{\spalignmaxcols}%
    \let\spalign@repeated@one=\spalign@repeated%
    \spalignmaxcols=\count255%
    \spalign@repeat{#1}{\spalignmaxcols}%
    \let\spalign@repeated@two=\spalign@repeated%
    \edef\spalign@barray{\noexpand\begin{array}{%
      \spalign@repeated@one|\spalign@repeated@two}}%
    \spalign@barray%
    }{\end{array}%
    }{\hskip-\arraycolsep\spalignmatdelimskip}%
  }%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\spalignsys}
%   System of equations with aligned operators and variables.
%    \begin{macrocode}
\spalign@def@star\spalignsys#1{%
  \ifspalign@star\else%
    \left\spalign@sysleftdelim\spalignsysdelimskip%
  \fi%
  \vcenter{%
    \def\spalignendline{\cr}%
    \openup1pt%
    \tabskip=0pt%
    \def\+{\mathbin{\phantom{+}}}%
    \def\={\mathrel{\phantom{=}}}%
    \def\.{}%
    \halign{%
%    \end{macrocode}
% Adding |{}| to each side of the align argument in the even columns causes
% binary operators ($+$, $-$, $\ldots$) and relations ($=$, $<$, $\ldots$) to
% use their natural spacing.  Assuming the even columns contain only binary
% operators (resp.\ only relations), these columns will all be the same width.
% The |\hfil| in the odd columns right-justifies.  There should be no spaces in
% the templates.
%    \begin{macrocode}
      \tabskip=\spalignsystabspace%      
      &$\hfil##$&${}##{}$\cr%
      \spalignretokenize{#1}\crcr%
      }%
%    \end{macrocode}
% It seems that one can't specify tabskip glue for after the last column when
% there are repeated templates.
%    \begin{macrocode}
    }\hskip-\spalignsystabspace%
  \ifspalign@star\else%
    \spalignsysdelimskip\right\spalign@sysrightdelim%
  \fi%
  }
%    \end{macrocode}
% \end{macro}
%    \begin{macrocode}
\makeatother
%    \end{macrocode}
% \Finale
\endinput