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|
% \iffalse meta-comment
%
%% File: l3tl.dtx Copyright (C) 1990-2012 The LaTeX3 Project
%%
%% It may be distributed and/or modified under the conditions of the
%% LaTeX Project Public License (LPPL), either version 1.3c of this
%% license or (at your option) any later version. The latest version
%% of this license is in the file
%%
%% http://www.latex-project.org/lppl.txt
%%
%% This file is part of the "l3kernel bundle" (The Work in LPPL)
%% and all files in that bundle must be distributed together.
%%
%% The released version of this bundle is available from CTAN.
%%
%% -----------------------------------------------------------------------
%%
%% The development version of the bundle can be found at
%%
%% http://www.latex-project.org/svnroot/experimental/trunk/
%%
%% for those people who are interested.
%%
%%%%%%%%%%%
%% NOTE: %%
%%%%%%%%%%%
%%
%% Snapshots taken from the repository represent work in progress and may
%% not work or may contain conflicting material! We therefore ask
%% people _not_ to put them into distributions, archives, etc. without
%% prior consultation with the LaTeX3 Project.
%%
%% -----------------------------------------------------------------------
%
%<*driver|package>
\RequirePackage{l3bootstrap}
\GetIdInfo$Id: l3tl.dtx 3991 2012-07-16 19:00:35Z joseph $
{L3 Token lists}
%</driver|package>
%<*driver>
\documentclass[full]{l3doc}
\begin{document}
\DocInput{\jobname.dtx}
\end{document}
%</driver>
% \fi
%
% \title{^^A
% The \pkg{l3tl} package\\ Token lists^^A
% \thanks{This file describes v\ExplFileVersion,
% last revised \ExplFileDate.}^^A
% }
%
% \author{^^A
% The \LaTeX3 Project\thanks
% {^^A
% E-mail:
% \href{mailto:latex-team@latex-project.org}
% {latex-team@latex-project.org}^^A
% }^^A
% }
%
% \date{Released \ExplFileDate}
%
% \maketitle
%
% \begin{documentation}
%
% \TeX{} works with tokens, and \LaTeX3 therefore provides a number of
% functions to deal with token lists. Token lists may be present directly in
% the argument to a function:
% \begin{verbatim}
% \foo:n { a collection of \tokens }
% \end{verbatim}
% or may be stored for processing in a so-called \enquote{token list
% variable}, which have the suffix \texttt{tl}:
% the argument to a function:
% \begin{verbatim}
% \foo:N \l_some_tl
% \end{verbatim}
% In both cases, functions are available to test an manipulate the lists
% of tokens, and these have the module prefix \texttt{tl}.
% In many cases, function which can be applied to token list variables
% are paired with similar functions for application to explicit lists
% of tokens: the two \enquote{views} of a token list are therefore collected
% together here.
%
% A token list can be seen either as a list of \enquote{items},
% or a list of \enquote{tokens}. An item is whatever \cs{use_none:n}
% grabs as its argument: either a single token or a brace group,
% with optional leading explicit space characters (each item is thus
% itself a token list). A token is either a normal \texttt{N} argument,
% or | |, |{|, or |}| (assuming normal \TeX{} category codes).
% Thus for example
% \begin{verbatim}
% { Hello } ~ world
% \end{verbatim}
% contains six items (\texttt{Hello}, \texttt{w}, \texttt{o}, \texttt{r},
% \texttt{l} and \texttt{d}), but thirteen tokens (|{|, \texttt{H}, \texttt{e},
% \texttt{l}, \texttt{l}, \texttt{o}, |}|, \verb*| |, \texttt{w}, \texttt{o},
% \texttt{r}, \texttt{l} and \texttt{d}).
% Functions which act on items are often faster than their analogue acting
% directly on tokens.
%
% \section{Creating and initialising token list variables}
%
% \begin{function}{\tl_new:N, \tl_new:c}
% \begin{syntax}
% \cs{tl_new:N} \meta{tl~var}
% \end{syntax}
% Creates a new \meta{tl~var} or raises an error if the
% name is already taken. The declaration is global. The
% \meta{tl~var} will initially be empty.
% \end{function}
%
% \begin{function}{\tl_const:Nn, \tl_const:Nx, \tl_const:cn, \tl_const:cx}
% \begin{syntax}
% \cs{tl_const:Nn} \meta{tl~var} \Arg{token list}
% \end{syntax}
% Creates a new constant \meta{tl~var} or raises an error
% if the name is already taken. The value of the
% \meta{tl~var} will be set globally to the
% \meta{token list}.
% \end{function}
%
% \begin{function}{\tl_clear:N, \tl_clear:c, \tl_gclear:N, \tl_gclear:c}
% \begin{syntax}
% \cs{tl_clear:N} \meta{tl~var}
% \end{syntax}
% Clears all entries from the \meta{tl~var} within the scope of
% the current \TeX{} group.
% \end{function}
%
% \begin{function}
% {\tl_clear_new:N, \tl_clear_new:c, \tl_gclear_new:N, \tl_gclear_new:c}
% \begin{syntax}
% \cs{tl_clear_new:N} \meta{tl~var}
% \end{syntax}
% Ensures that the \meta{tl~var} exists globally by applying
% \cs{tl_new:N} if necessary, then applies \cs{tl_(g)clear:N} to leave
% the \meta{tl~var} empty.
% \end{function}
%
% \begin{function}
% {
% \tl_set_eq:NN, \tl_set_eq:cN, \tl_set_eq:Nc, \tl_set_eq:cc,
% \tl_gset_eq:NN, \tl_gset_eq:cN, \tl_gset_eq:Nc, \tl_gset_eq:cc
% }
% \begin{syntax}
% \cs{tl_set_eq:NN} \meta{tl~var_1} \meta{tl~var_2}
% \end{syntax}
% Sets the content of \meta{tl~var_1} equal to that of
% \meta{tl~var_2}.
% \end{function}
%
% \begin{function}[added = 2012-05-18]
% {
% \tl_concat:NNN, \tl_concat:ccc,
% \tl_gconcat:NNN, \tl_gconcat:ccc
% }
% \begin{syntax}
% \cs{tl_concat:NNN} \meta{tl~var_1} \meta{tl~var_2} \meta{tl~var_3}
% \end{syntax}
% Concatenates the content of \meta{tl~var_2} and \meta{tl~var_3}
% together and saves the result in \meta{tl~var_1}. The \meta{tl~var_2}
% will be placed at the left side of the new token list.
% \end{function}
%
% \begin{function}[EXP, pTF, added=2012-03-03]{\tl_if_exist:N, \tl_if_exist:c}
% \begin{syntax}
% \cs{tl_if_exist_p:N} \meta{tl~var}
% \cs{tl_if_exist:NTF} \meta{tl~var} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests whether the \meta{tl~var} is currently defined. This does not
% check that the \meta{tl~var} really is a token list variable.
% \end{function}
%
% \section{Adding data to token list variables}
%
% \begin{function}
% {
% \tl_set:Nn, \tl_set:NV, \tl_set:Nv, \tl_set:No, \tl_set:Nf, \tl_set:Nx,
% \tl_set:cn, \tl_set:NV, \tl_set:Nv, \tl_set:co, \tl_set:cf, \tl_set:cx,
% \tl_gset:Nn, \tl_gset:NV, \tl_gset:Nv,
% \tl_gset:No, \tl_gset:Nf, \tl_gset:Nx,
% \tl_gset:cn, \tl_gset:cV, \tl_gset:cv,
% \tl_gset:co, \tl_gset:cf, \tl_gset:cx
% }
% \begin{syntax}
% \cs{tl_set:Nn} \meta{tl~var} \Arg{tokens}
% \end{syntax}
% Sets \meta{tl~var} to contain \meta{tokens},
% removing any previous content from the variable.
% \end{function}
%
% \begin{function}
% {
% \tl_put_left:Nn, \tl_put_left:NV, \tl_put_left:No, \tl_put_left:Nx,
% \tl_put_left:cn, \tl_put_left:cV, \tl_put_left:co, \tl_put_left:cx,
% \tl_gput_left:Nn, \tl_gput_left:NV, \tl_gput_left:No, \tl_gput_left:Nx,
% \tl_gput_left:cn, \tl_gput_left:cV, \tl_gput_left:co, \tl_gput_left:cx
% }
% \begin{syntax}
% \cs{tl_put_left:Nn} \meta{tl~var} \Arg{tokens}
% \end{syntax}
% Appends \meta{tokens} to the left side of the current content of
% \meta{tl~var}.
% \end{function}
%
% \begin{function}
% {
% \tl_put_right:Nn, \tl_put_right:NV, \tl_put_right:No, \tl_put_right:Nx,
% \tl_put_right:cn, \tl_put_right:cV, \tl_put_right:co, \tl_put_right:cx,
% \tl_gput_right:Nn, \tl_gput_right:NV, \tl_gput_right:No,
% \tl_gput_right:Nx,
% \tl_gput_right:cn, \tl_gput_right:cV, \tl_gput_right:co,
% \tl_gput_right:cx
% }
% \begin{syntax}
% \cs{tl_put_right:Nn} \meta{tl~var} \Arg{tokens}
% \end{syntax}
% Appends \meta{tokens} to the right side of the current content of
% \meta{tl~var}.
% \end{function}
%
% \section{Modifying token list variables}
%
% \begin{function}[updated = 2011-08-11]
% {
% \tl_replace_once:Nnn, \tl_replace_once:cnn,
% \tl_greplace_once:Nnn, \tl_greplace_once:cnn
% }
% \begin{syntax}
% \cs{tl_replace_once:Nnn} \meta{tl~var} \Arg{old tokens} \Arg{new tokens}
% \end{syntax}
% Replaces the first (leftmost) occurrence of \meta{old tokens} in the
% \meta{tl~var} with \meta{new tokens}. \meta{Old tokens}
% cannot contain |{|, |}| or |#|
% (assuming normal \TeX{} category codes).
% \end{function}
%
% \begin{function}[updated = 2011-08-11]
% {
% \tl_replace_all:Nnn, \tl_replace_all:cnn,
% \tl_greplace_all:Nnn, \tl_greplace_all:cnn
% }
% \begin{syntax}
% \cs{tl_replace_all:Nnn} \meta{tl~var} \Arg{old tokens} \Arg{new tokens}
% \end{syntax}
% Replaces all occurrences of \meta{old tokens} in the
% \meta{tl~var} with \meta{new tokens}. \meta{Old tokens}
% cannot contain |{|, |}| or |#|
% (assuming normal \TeX{} category codes). As this function
% operates from left to right, the pattern \meta{old tokens}
% may remain after the replacement (see \cs{tl_remove_all:Nn}
% for an example). The assignment is
% restricted to the current \TeX{} group.
% \end{function}
%
% \begin{function}[updated = 2011-08-11]
% {
% \tl_remove_once:Nn, \tl_remove_once:cn,
% \tl_gremove_once:Nn, \tl_gremove_once:cn
% }
% \begin{syntax}
% \cs{tl_remove_once:Nn} \meta{tl~var} \Arg{tokens}
% \end{syntax}
% Removes the first (leftmost) occurrence of \meta{tokens} from the
% \meta{tl~var}. \meta{Tokens} cannot contain |{|, |}| or
% |#| (assuming normal \TeX{} category codes).
% \end{function}
%
% \begin{function}[updated = 2011-08-11]
% {
% \tl_remove_all:Nn, \tl_remove_all:cn,
% \tl_gremove_all:Nn, \tl_gremove_all:cn
% }
% \begin{syntax}
% \cs{tl_remove_all:Nn} \meta{tl~var} \Arg{tokens}
% \end{syntax}
% Removes all occurrences of \meta{tokens} from the
% \meta{tl~var}. \meta{Tokens} cannot contain |{|, |}| or
% |#| (assuming normal \TeX{} category codes). As this function
% operates from left to right, the pattern \meta{tokens}
% may remain after the removal, for instance,
% \begin{quote}
% \cs{tl_set:Nn} \cs{l_tmpa_tl} |{abbccd}|
% \cs{tl_remove_all:Nn} \cs{l_tmpa_tl} |{bc}|
% \end{quote}
% will result in \cs{l_tmpa_tl} containing \texttt{abcd}.
% \end{function}
%
% \section{Reassigning token list category codes}
%
% \begin{function}[updated = 2011-12-18]
% {
% \tl_set_rescan:Nnn, \tl_set_rescan:Nno, \tl_set_rescan:Nnx,
% \tl_set_rescan:cnn, \tl_set_rescan:cno, \tl_set_rescan:cnx,
% \tl_gset_rescan:Nnn, \tl_gset_rescan:Nno, \tl_gset_rescan:Nnx,
% \tl_gset_rescan:cnn, \tl_gset_rescan:cno, \tl_gset_rescan:cnx
% }
% \begin{syntax}
% \cs{tl_set_rescan:Nnn} \meta{tl~var} \Arg{setup} \Arg{tokens}
% \end{syntax}
% Sets \meta{tl~var} to contain \meta{tokens},
% applying the category code r{\'e}gime specified in the
% \meta{setup} before carrying out the assignment. This allows the
% \meta{tl~var} to contain material with category codes
% other than those that apply when \meta{tokens} are absorbed. See also
% \cs{tl_rescan:nn}.
% \end{function}
%
% \begin{function}[updated = 2011-12-18]{\tl_rescan:nn}
% \begin{syntax}
% \cs{tl_rescan:nn} \Arg{setup} \Arg{tokens}
% \end{syntax}
% Rescans \meta{tokens} applying the category code r\'egime specified
% in the \meta{setup}, and leaves the resulting tokens in the input
% stream. See also \cs{tl_set_rescan:Nnn}.
% \end{function}
%
% \section{Reassigning token list character codes}
%
% \begin{function}{\tl_to_lowercase:n}
% \begin{syntax}
% \cs{tl_to_lowercase:n} \Arg{tokens}
% \end{syntax}
% Works through all of the \meta{tokens}, replacing each character
% with the lower case equivalent as defined by \cs{char_set_lccode:nn}.
% Characters with no defined lower case character code are left
% unchanged. This process does not alter the category code assigned
% to the \meta{tokens}.
% \begin{texnote}
% This is the \TeX{} primitive \tn{lowercase} renamed.
% As a result, this function takes place on execution and
% not on expansion.
% \end{texnote}
% \end{function}
%
% \begin{function}{\tl_to_uppercase:n}
% \begin{syntax}
% \cs{tl_to_uppercase:n} \Arg{tokens}
% \end{syntax}
% Works through all of the \meta{tokens}, replacing each character
% with the upper case equivalent as defined by \cs{char_set_uccode:nn}.
% Characters with no defined lower case character code are left
% unchanged. This process does not alter the category code assigned
% to the \meta{tokens}.
% \begin{texnote}
% This is the \TeX{} primitive \tn{uppercase} renamed.
% As a result, this function takes place on execution and
% not on expansion.
% \end{texnote}
% \end{function}
%
% \section{Token list conditionals}
%
% \begin{function}[EXP,pTF]{\tl_if_blank:n, \tl_if_blank:V, \tl_if_blank:o}
% \begin{syntax}
% \cs{tl_if_blank_p:n} \Arg{token list}
% \cs{tl_if_blank:nTF} \Arg{token list} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the \meta{token list} consists only of blank spaces
% (\emph{i.e.}~contains no item). The test is \texttt{true} if
% \meta{token list} is zero or more explicit tokens of character code~$32$
% and category code~$10$, and is \texttt{false} otherwise.
% \end{function}
%
% \begin{function}[EXP,pTF]{\tl_if_empty:N, \tl_if_empty:c}
% \begin{syntax}
% \cs{tl_if_empty_p:N} \meta{tl var}
% \cs{tl_if_empty:NTF} \meta{tl var} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the \meta{token list variable} is entirely empty
% (\emph{i.e.}~contains no tokens at all).
% \end{function}
%
% \begin{function}[added = 2012-05-24, updated = 2012-06-05, EXP,pTF]
% {\tl_if_empty:n, \tl_if_empty:V, \tl_if_empty:o}
% \begin{syntax}
% \cs{tl_if_empty_p:n} \Arg{token list}
% \cs{tl_if_empty:nTF} \Arg{token list} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the \meta{token list} is entirely empty
% (\emph{i.e.}~contains no tokens at all).
% \end{function}
%
% \begin{function}[EXP,pTF]
% {\tl_if_eq:NN, \tl_if_eq:Nc, \tl_if_eq:cN, \tl_if_eq:cc}
% \begin{syntax}
% \cs{tl_if_eq_p:NN} \Arg{tl var_1} \Arg{tl var_2}
% \cs{tl_if_eq:NNTF} \Arg{tl var_1} \Arg{tl var_2} \Arg{true code} \Arg{false code}
% \end{syntax}
% Compares the content of two \meta{token list variables} and
% is logically \texttt{true} if the two contain the same list of
% tokens (\emph{i.e.}~identical in both the list of characters they
% contain and the category codes of those characters). Thus for example
% \begin{verbatim}
% \tl_set:Nn \l_tmpa_tl { abc }
% \tl_set:Nx \l_tmpb_tl { \tl_to_str:n { abc } }
% \tl_if_eq_p:NN \l_tmpa_tl \l_tmpb_tl
% \end{verbatim}
% is logically \texttt{false}.
% \end{function}
%
% \begin{function}[TF]{\tl_if_eq:nn}
% \begin{syntax}
% \cs{tl_if_eq:nnTF} \meta{token list_1} \Arg{token list_2} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if \meta{token list_1} and \meta{token list_2} are equal, both in
% respect of character codes and category codes.
% \end{function}
%
% \begin{function}[TF]{\tl_if_in:Nn, \tl_if_in:cn}
% \begin{syntax}
% \cs{tl_if_in:NnTF} \meta{tl~var} \Arg{token list} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the \meta{token list} is found in the content of the
% \meta{token list variable}. The \meta{token list} cannot contain
% the tokens |{|, |}| or |#| (assuming the usual \TeX{} category
% codes apply).
% \end{function}
%
% \begin{function}[TF]
% {\tl_if_in:nn, \tl_if_in:Vn, \tl_if_in:on, \tl_if_in:no}
% \begin{syntax}
% \cs{tl_if_in:nnTF} \Arg{token list_1} \Arg{token list_2} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if <token list_2> is found inside <token list_1>.
% The \meta{token list} cannot contain the tokens |{|, |}| or |#|
% (assuming the usual \TeX{} category codes apply).
% \end{function}
%
% \begin{function}[updated = 2011-08-13, EXP,pTF]
% {\tl_if_single:N, \tl_if_single:c}
% \begin{syntax}
% \cs{tl_if_single_p:N} \Arg{tl~var}
% \cs{tl_if_single:NTF} \Arg{tl~var} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the content of the \meta{tl~var} consists of a single item,
% \emph{i.e.}~is either a single normal token (excluding spaces,
% and brace tokens) or a single brace group, surrounded by optional
% spaces on both sides. In other words, such a token list has token count
% $1$ according to \cs{tl_count:N}.
% \end{function}
%
% \begin{function}[updated = 2011-08-13, EXP,pTF]{\tl_if_single:n}
% \begin{syntax}
% \cs{tl_if_single_p:n} \Arg{token list}
% \cs{tl_if_single:nTF} \Arg{token list} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the token list has exactly one item, \emph{i.e.}~is either
% a single normal token or a single brace group, surrounded by
% optional spaces on both sides. In other words, such a token list
% has token count $1$ according to \cs{tl_count:n}.
% \end{function}
%
% \begin{function}[added = 2012-06-03, EXP]{\tl_case:Nnn, \tl_case:cnn}
% \begin{syntax}
% \cs{tl_case:Nnn} \meta{test token list variable} \\
% ~~"{" \\
% ~~~~\meta{token list variable case_1} \Arg{code case_1} \\
% ~~~~\meta{token list variable case_2} \Arg{code case_2} \\
% ~~~~\ldots \\
% ~~~~\meta{token list variable case_n} \Arg{code case_n} \\
% ~~"}" \\
% ~~\Arg{else code}
% \end{syntax}
% This function compares the \meta{test token list variable} in turn
% with each of the \meta{token list variable cases}. If the two
% are equal (as described for
% \cs{tl_if_eq:nnTF}
% then the associated \meta{code} is left in the input
% stream. If none of the tests are \texttt{true} then the
% \texttt{else code} will be left in the input stream.
% \end{function}
%
% \section{Mapping to token lists}
%
% \begin{function}[updated = 2012-06-29, rEXP]
% {\tl_map_function:NN, \tl_map_function:cN}
% \begin{syntax}
% \cs{tl_map_function:NN} \meta{tl~var} \meta{function}
% \end{syntax}
% Applies \meta{function} to every \meta{item} in the \meta{tl~var}.
% The \meta{function} will receive one argument for each iteration.
% This may be a number of tokens if the \meta{item} was stored within
% braces. Hence the \meta{function} should anticipate receiving
% \texttt{n}-type arguments. See also \cs{tl_map_function:nN}.
% \end{function}
%
% \begin{function}[updated = 2012-06-29, rEXP]{\tl_map_function:nN}
% \begin{syntax}
% \cs{tl_map_function:nN} \meta{token list} \meta{function}
% \end{syntax}
% Applies \meta{function} to every \meta{item} in the \meta{token list},
% The \meta{function} will receive one argument for each iteration.
% This may be a number of tokens if the \meta{item} was stored within
% braces. Hence the \meta{function} should anticipate receiving
% \texttt{n}-type arguments. See also \cs{tl_map_function:NN}.
% \end{function}
%
% \begin{function}[updated = 2012-06-29]
% {\tl_map_inline:Nn, \tl_map_inline:cn}
% \begin{syntax}
% \cs{tl_map_inline:Nn} \meta{tl~var} \Arg{inline function}
% \end{syntax}
% Applies the \meta{inline function} to every \meta{item} stored within the
% \meta{tl~var}. The \meta{inline function} should consist of code which
% will receive the \meta{item} as |#1|. One in line mapping can be nested
% inside another. See also \cs{tl_map_function:Nn}.
% \end{function}
%
% \begin{function}[updated = 2012-06-29]{\tl_map_inline:nn}
% \begin{syntax}
% \cs{tl_map_inline:nn} \meta{token list} \Arg{inline function}
% \end{syntax}
% Applies the \meta{inline function} to every \meta{item} stored within the
% \meta{token list}. The \meta{inline function} should consist of code which
% will receive the \meta{item} as |#1|. One in line mapping can be nested
% inside another. See also \cs{tl_map_function:nn}.
% \end{function}
%
% \begin{function}[updated = 2012-06-29]
% {\tl_map_variable:NNn, \tl_map_variable:cNn}
% \begin{syntax}
% \cs{tl_map_variable:NNn} \meta{tl~var} \meta{variable} \Arg{function}
% \end{syntax}
% Applies the \meta{function} to every \meta{item} stored
% within the \meta{tl~var}. The \meta{function} should consist of code
% which will receive the \meta{item} stored in the \meta{variable}.
% One variable mapping can be nested inside another. See also
% \cs{tl_map_inline:Nn}.
% \end{function}
%
% \begin{function}[updated = 2012-06-29]{\tl_map_variable:nNn}
% \begin{syntax}
% \cs{tl_map_variable:nNn} \meta{token list} \meta{variable} \Arg{function}
% \end{syntax}
% Applies the \meta{function} to every \meta{item} stored
% within the \meta{token list}. The \meta{function} should consist of code
% which will receive the \meta{item} stored in the \meta{variable}.
% One variable mapping can be nested inside another. See also
% \cs{tl_map_inline:nn}.
% \end{function}
%
% \begin{function}[updated = 2012-06-29, rEXP]{\tl_map_break:}
% \begin{syntax}
% \cs{tl_map_break:}
% \end{syntax}
% Used to terminate a \cs{tl_map_\ldots} function before all
% entries in the \meta{token list variable} have been processed. This
% will normally take place within a conditional statement, for example
% \begin{verbatim}
% \tl_map_inline:Nn \l_my_tl
% {
% \str_if_eq:nnTF { #1 } { bingo }
% { \tl_map_break: }
% {
% % Do something useful
% }
% }
% \end{verbatim}
% Use outside of a \cs{tl_map_\ldots} scenario will lead low
% level \TeX{} errors.
% \begin{texnote}
% When the mapping is broken, additional tokens may be inserted by the
% internal macro \cs{__prg_break_point:Nn} before the \meta{tokens} are
% inserted into the input stream.
% This will depend on the design of the mapping function.
% \end{texnote}
% \end{function}
%
% \begin{function}[updated = 2012-06-29, rEXP]{\tl_map_break:n}
% \begin{syntax}
% \cs{tl_map_break:n} \Arg{tokens}
% \end{syntax}
% Used to terminate a \cs{tl_map_\ldots} function before all
% entries in the \meta{token list variable} have been processed, inserting
% the \meta{tokens} after the mapping has ended. This will
% normally take place within a conditional statement, for example
% \begin{verbatim}
% \tl_map_inline:Nn \l_my_tl
% {
% \str_if_eq:nnTF { #1 } { bingo }
% { \tl_map_break:n { <tokens> } }
% {
% % Do something useful
% }
% }
% \end{verbatim}
% Use outside of a \cs{tl_map_\ldots} scenario will lead to low
% level \TeX{} errors.
% \begin{texnote}
% When the mapping is broken, additional tokens may be inserted by the
% internal macro \cs{__prg_break_point:Nn} before the \meta{tokens} are
% inserted into the input stream.
% This will depend on the design of the mapping function.
% \end{texnote}
% \end{function}
%
% \section{Using token lists}
%
% \begin{function}[EXP]{\tl_to_str:N, \tl_to_str:c}
% \begin{syntax}
% \cs{tl_to_str:N} \meta{tl~var}
% \end{syntax}
% Converts the content of the \meta{tl~var} into a series of characters
% with category code $12$ (other) with the exception of spaces, which
% retain category code $10$ (space). This \meta{string} is then left
% in the input stream.
% \end{function}
%
% \begin{function}[EXP]{\tl_to_str:n}
% \begin{syntax}
% \cs{tl_to_str:n} \Arg{tokens}
% \end{syntax}
% Converts the given \meta{tokens} into a series of characters with
% category code $12$ (other) with the exception of spaces, which
% retain category code $10$ (space). This \meta{string} is then left
% in the input stream. Note that this function requires only a single
% expansion.
% \begin{texnote}
% This is the \eTeX{} primitive \tn{detokenize}. Hence its argument
% \emph{must} be given within braces.
% \end{texnote}
% \end{function}
%
% \begin{function}[EXP]{\tl_use:N, \tl_use:c}
% \begin{syntax}
% \cs{tl_use:N} \meta{tl~var}
% \end{syntax}
% Recovers the content of a \meta{tl~var} and places it
% directly in the input stream. An error will be raised if the variable
% does not exist or if it is invalid. Note that it is possible to use
% a \meta{tl~var} directly without an accessor function.
% \end{function}
%
% \section{Working with the content of token lists}
%
% \begin{function}[added = 2012-05-13, EXP]
% {\tl_count:n, \tl_count:V, \tl_count:o}
% \begin{syntax}
% \cs{tl_count:n} \Arg{tokens}
% \end{syntax}
% Counts the number of \meta{items} in \meta{tokens} and leaves this
% information in the input stream. Unbraced tokens count as one
% element as do each token group (|{|\ldots|}|). This process will
% ignore any unprotected spaces within \meta{tokens}. See also
% \cs{tl_count:N}. This function requires three expansions,
% giving an \meta{integer denotation}.
% \end{function}
%
% \begin{function}[added = 2012-05-13, EXP]{\tl_count:N, \tl_count:c}
% \begin{syntax}
% \cs{tl_count:N} \Arg{tl~var}
% \end{syntax}
% Counts the number of token groups in the \meta{tl~var}
% and leaves this information in the input stream. Unbraced tokens
% count as one element as do each token group (|{|\ldots|}|). This
% process will ignore any unprotected spaces within \meta{tokens}.
% See also \cs{tl_count:n}. This function requires three expansions,
% giving an \meta{integer denotation}.
% \end{function}
%
% \begin{function}[updated = 2012-01-08, EXP]
% {\tl_reverse:n, \tl_reverse:V, \tl_reverse:o}
% \begin{syntax}
% \cs{tl_reverse:n} \Arg{token list}
% \end{syntax}
% Reverses the order of the \meta{items} in the \meta{token list},
% so that \meta{item_1}\meta{item_2}\meta{item_3} \ldots \meta{item_n}
% becomes \meta{item_n}\ldots \meta{item_3}\meta{item_2}\meta{item_1}.
% This process will preserve unprotected space within the
% \meta{token list}. Tokens are not reversed within braced token
% groups, which keep their outer set of braces.
% In situations where performance is important,
% consider \cs{tl_reverse_items:n}.
% See also \cs{tl_reverse:N}.
% \begin{texnote}
% The result is returned within the \tn{unexpanded}
% primitive (\cs{exp_not:n}), which means that the token
% list will not expand further when appearing in an x-type
% argument expansion.
% \end{texnote}
% \end{function}
%
% \begin{function}[updated = 2012-01-08]
% {\tl_reverse:N, \tl_reverse:c, \tl_greverse:N, \tl_greverse:c}
% \begin{syntax}
% \cs{tl_reverse:N} \Arg{tl~var}
% \end{syntax}
% Reverses the order of the \meta{items} stored in \meta{tl~var}, so
% that \meta{item_1}\meta{item_2}\meta{item_3} \ldots \meta{item_n}
% becomes \meta{item_n}\ldots \meta{item_3}\meta{item_2}\meta{item_1}.
% This process will preserve unprotected spaces within the
% \meta{token list variable}. Braced token groups are copied without
% reversing the order of tokens, but keep the outer set of braces.
% See also \cs{tl_reverse:n}.
% \end{function}
%
% \begin{function}[added = 2012-01-08, EXP]{\tl_reverse_items:n}
% \begin{syntax}
% \cs{tl_reverse_items:n} \Arg{token list}
% \end{syntax}
% Reverses the order of the \meta{items} stored in \meta{tl~var},
% so that \Arg{item_1}\Arg{item_2}\Arg{item_3} \ldots \Arg{item_n}
% becomes \Arg{item_n} \ldots{} \Arg{item_3}\Arg{item_2}\Arg{item_1}.
% This process will remove any unprotected space within the
% \meta{token list}. Braced token groups are copied without
% reversing the order of tokens, and keep the outer set of braces.
% Items which are initially not braced are copied with braces in
% the result. In cases where preserving spaces is important,
% consider \cs{tl_reverse:n} or \cs{tl_reverse_tokens:n}.
% \begin{texnote}
% The result is returned within the \tn{unexpanded}
% primitive (\cs{exp_not:n}), which means that the token
% list will not expand further when appearing in an x-type
% argument expansion.
% \end{texnote}
% \end{function}
%
% \begin{function}[added = 2011-07-09, updated = 2012-06-25, EXP]
% {\tl_trim_spaces:n}
% \begin{syntax}
% \cs{tl_trim_spaces:n} \meta{token list}
% \end{syntax}
% Removes any leading and trailing explicit space characters
% from the \meta{token list} and leaves the result in the input
% stream.
% \begin{texnote}
% The result is returned within the \tn{unexpanded}
% primitive (\cs{exp_not:n}), which means that the token
% list will not expand further when appearing in an x-type
% argument expansion.
% \end{texnote}
% \end{function}
%
% \begin{function}[added = 2011-07-09]
% {
% \tl_trim_spaces:N, \tl_trim_spaces:c,
% \tl_gtrim_spaces:N, \tl_gtrim_spaces:c
% }
% \begin{syntax}
% \cs{tl_trim_spaces:N} \meta{tl~var}
% \end{syntax}
% Removes any leading and trailing explicit space characters
% from the content of the \meta{tl~var}.
% \end{function}
%
% \section{The first token from a token list}
%
% Functions which deal with either only the very first token of a
% token list or everything except the first token.
%
% \begin{function}[updated = 2012-02-08, EXP]
% {\tl_head:N, \tl_head:n, \tl_head:V, \tl_head:v, \tl_head:f}
% \begin{syntax}
% \cs{tl_head:n} \Arg{tokens}
% \end{syntax}
% Leaves in the input stream the first non-space token from the
% \meta{tokens}. Any leading space tokens will be discarded, and thus for
% example
% \begin{verbatim}
% \tl_head:n { abc }
% \end{verbatim}
% and
% \begin{verbatim}
% \tl_head:n { ~ abc }
% \end{verbatim}
% will both leave |a| in the input stream.
% An empty list of \meta{tokens} or one which consists
% only of space (category code $10$) tokens will result in \cs{tl_head:n}
% leaving nothing in the input stream.
% \begin{texnote}
% The result is returned within the \tn{unexpanded}
% primitive (\cs{exp_not:n}), which means that the token
% list will not expand further when appearing in an x-type
% argument expansion.
% \end{texnote}
% \end{function}
%
% \begin{function}[EXP]{\tl_head:w}
% \begin{syntax}
% \cs{tl_head:w} \meta{tokens} \cs{q_stop}
% \end{syntax}
% Leaves in the input stream the first non-space token from the
% \meta{tokens}. An empty list of \meta{tokens} or one which consists
% only of space (category code $10$) tokens will result in an error, and
% thus \meta{tokens} must \emph{not} be \enquote{blank} as determined by
% \cs{tl_if_blank:n(TF)}. This function requires only a single expansion,
% and thus is suitable for use within an \texttt{o}-type expansion. In
% general, \cs{tl_head:n} should be preferred if the number of expansions
% is not critical.
% \end{function}
%
% \begin{function}[updated = 2012-02-08, EXP]
% {\tl_tail:N, \tl_tail:n, \tl_tail:V, \tl_tail:v, \tl_tail:f}
% \begin{syntax}
% \cs{tl_tail:n} \Arg{tokens}
% \end{syntax}
% Discards the all leading space tokens and the first non-space token
% in the \meta{tokens}, and leaves the remaining tokens in the
% input stream. Thus for example
% \begin{verbatim}
% \tl_tail:n { abc }
% \end{verbatim}
% and
% \begin{verbatim}
% \tl_tail:n { ~ abc }
% \end{verbatim}
% will both leave |bc| in the input stream.
% An empty list of \meta{tokens} or one which consists
% only of space (category code $10$) tokens will result in \cs{tl_tail:n}
% leaving nothing in the input stream.
% \begin{texnote}
% The result is returned within the \tn{unexpanded}
% primitive (\cs{exp_not:n}), which means that the token
% list will not expand further when appearing in an x-type
% argument expansion.
% \end{texnote}
% \end{function}
%
% \begin{function}[EXP]{\tl_tail:w}
% \begin{syntax}
% \cs{tl_tail:w} \Arg{tokens} \cs{q_stop}
% \end{syntax}
% Discards the all leading space tokens and the first non-space token
% in the \meta{tokens}, and leaves the remaining tokens in the
% input stream.
% An empty list of \meta{tokens} or one which consists
% only of space (category code $10$) tokens will result in an error, and
% thus \meta{tokens} must \emph{not} be \enquote{blank} as determined by
% \cs{tl_if_blank:n(TF)}. This function requires only a single expansion,
% and thus is suitable for use within an \texttt{o}-type expansion. In
% general, \cs{tl_tail:n} should be preferred if the number of expansions
% is not critical.
% \end{function}
%
% \begin{function}[added = 2011-08-10, EXP]{\str_head:n,\str_tail:n}
% \begin{syntax}
% \cs{str_head:n} \Arg{tokens}
% \cs{str_tail:n} \Arg{tokens}
% \end{syntax}
% Converts the \meta{tokens} into a string, as described for
% \cs{tl_to_str:n}. The \cs{str_head:n} function then leaves
% the first character of this string in the input stream.
% The \cs{str_tail:n} function leaves all characters except
% the first in the input stream. The first character may be
% a space. If the \meta{tokens} argument is entirely empty,
% nothing is left in the input stream.
% \end{function}
%
% \begin{function}[updated = 2012-07-09, EXP, pTF]{\tl_if_head_eq_catcode:nN}
% \begin{syntax}
% \cs{tl_if_head_eq_catcode_p:nN} \Arg{token list} \meta{test token}
% \cs{tl_if_head_eq_catcode:nNTF} \Arg{token list} \meta{test token}
% ~~\Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the first \meta{token} in the \meta{token list} has the
% same category code as the \meta{test token}. In the case where the
% \meta{token list} is empty, the test will always be \texttt{false}.
% \end{function}
%
% \begin{function}[updated = 2012-07-09, EXP, pTF]
% {\tl_if_head_eq_charcode:nN, \tl_if_head_eq_charcode:fN}
% \begin{syntax}
% \cs{tl_if_head_eq_charcode_p:nN} \Arg{token list} \meta{test token}
% \cs{tl_if_head_eq_charcode:nNTF} \Arg{token list} \meta{test token}
% ~~\Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the first \meta{token} in the \meta{token list} has the
% same character code as the \meta{test token}. In the case where the
% \meta{token list} is empty, the test will always be \texttt{false}.
% \end{function}
%
% \begin{function}[updated = 2012-07-09, EXP, pTF]{\tl_if_head_eq_meaning:nN}
% \begin{syntax}
% \cs{tl_if_head_eq_meaning_p:nN} \Arg{token list} \meta{test token}
% \cs{tl_if_head_eq_meaning:nNTF} \Arg{token list} \meta{test token}
% ~~\Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the first \meta{token} in the \meta{token list} has the
% same meaning as the \meta{test token}. In the case where
% \meta{token list} is empty, the test will always be \texttt{false}.
% \end{function}
%
% \begin{function}[added = 2012-07-08, EXP, pTF]{\tl_if_head_is_group:n}
% \begin{syntax}
% \cs{tl_if_head_is_group_p:n} \Arg{token list}
% \cs{tl_if_head_is_group:nTF} \Arg{token list} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the first \meta{token} in the \meta{token list}
% is an explicit begin-group character (with category code~1
% and any character code), in other words, if the \meta{token list}
% starts with a brace group. In particular, the test is \texttt{false}
% if the \meta{token list} starts with an implicit token such as
% \cs{c_group_begin_token}, or if it empty.
% This function is useful to implement actions on token lists on
% a token by token basis.
% \end{function}
%
% \begin{function}[added = 2012-07-08, EXP, pTF]{\tl_if_head_is_N_type:n}
% \begin{syntax}
% \cs{tl_if_head_is_N_type_p:n} \Arg{token list}
% \cs{tl_if_head_is_N_type:nTF} \Arg{token list} \Arg{true code} \Arg{false code}
% \end{syntax}
% Tests if the first \meta{token} in the \meta{token list}
% is a normal \texttt{N}-type argument. In other words,
% it is neither an explicit space character (with category code~10
% and character code~32) nor an explicit begin-group character
% (with category code~1 and any character code). An empty
% argument yields \texttt{false}, as it does not have a \enquote{normal}
% first token.
% This function is useful to implement actions on token lists on
% a token by token basis.
% \end{function}
%
% \begin{function}[updated = 2012-07-08, EXP, pTF]{\tl_if_head_is_space:n}
% \begin{syntax}
% \cs{tl_if_head_is_space_p:n} \Arg{token list}
% \cs{tl_if_head_is_space:nTF} \Arg{token list} \Arg{true code} \Arg{false code}
% \end{syntax}
%^^A We need to add a discussion of
%^^A explicit vs implicit tokens somewhere in the doc.
% Tests if the first \meta{token} in the \meta{token list}
% is an explicit space character (with category code~$10$
% and character code~$32$). If \meta{token list} starts with
% an implicit token such as \cs{c_space_token}, the test
% will yield \texttt{false}, as well as if the argument is empty.
% This function is useful to implement actions on token lists on
% a token by token basis.
% \begin{texnote}
% When \TeX{} reads a character of category code $10$ for the
% first time, it is converted to an explicit space token, with
% character code $32$, regardless of the initial character code.
% \enquote{Funny} spaces with a different category code, can be produced
% using \tn{lowercase}. Explicit spaces are also produced
% as a result of \cs{token_to_str:N}, \cs{tl_to_str:n}, etc.
% \end{texnote}
% \end{function}
%
% \section{Viewing token lists}
%
% \begin{function}{\tl_show:N, \tl_show:c}
% \begin{syntax}
% \cs{tl_show:N} \meta{tl~var}
% \end{syntax}
% Displays the content of the \meta{tl~var} on the terminal.
% \begin{texnote}
% \cs{tl_show:N} is the \TeX{} primitive \tn{show}.
% \end{texnote}
% \end{function}
%
% \begin{function}{\tl_show:n}
% \begin{syntax}
% \cs{tl_show:n} \meta{token list}
% \end{syntax}
% Displays the \meta{token list} on the terminal.
% \begin{texnote}
% \cs{tl_show:n} is the \eTeX{} primitive \tn{showtokens}.
% \end{texnote}
% \end{function}
%
% \section{Constant token lists}
%
% \begin{variable}[updated = 2011-08-18]{\c_job_name_tl}
% Constant that gets the \enquote{job name} assigned when \TeX{} starts.
% \begin{texnote}
% This is the new name for the primitive \tn{jobname}. It is a constant
% that is set by \TeX{} and should not be overwritten by the package.
% \end{texnote}
% \end{variable}
%
% \begin{variable}{\c_empty_tl}
% Constant that is always empty.
% \end{variable}
%
% \begin{variable}{\c_space_tl}
% A space token contained in a token list (compare this with
% \cs{c_space_token}). For use where an explicit space is required.
% \end{variable}
%
% \section{Scratch token lists}
%
% \begin{variable}{\l_tmpa_tl, \l_tmpb_tl}
% Scratch token lists for local assignment. These are never used by
% the kernel code, and so are safe for use with any \LaTeX3-defined
% function. However, they may be overwritten by other non-kernel
% code and so should only be used for short-term storage.
% \end{variable}
%
% \begin{variable}{\g_tmpa_tl, \g_tmpb_tl}
% Scratch token lists for global assignment. These are never used by
% the kernel code, and so are safe for use with any \LaTeX3-defined
% function. However, they may be overwritten by other non-kernel
% code and so should only be used for short-term storage.
% \end{variable}
%
% \section{Internal functions}
%
% \begin{function}{\__tl_trim_spaces:nn}
% \begin{syntax}
% \cs{__tl_trim_spaces:nn} |{ \q_mark| \meta{token list} |}| \Arg{continuation}
% \end{syntax}
% This function removes all leading and trailing explicit space
% characters from the \meta{token list}, and expands to the
% \meta{continuation}, followed by a brace group containing
% \cs{use_none:n} \cs{q_mark} \meta{trimmed token list}. For
% instance, \cs{tl_trim_spaces:n} is implemented by taking the
% \meta{continuation} to be \cs{exp_not:o}, and the \texttt{o}-type
% expansion removes the \cs{q_mark}. This function is also used in
% \pkg{l3clist}.
% \end{function}
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3tl} implementation}
%
% \begin{macrocode}
%<*initex|package>
% \end{macrocode}
%
% \begin{macrocode}
%<@@=tl>
% \end{macrocode}
%
% \begin{macrocode}
%<*package>
\ProvidesExplPackage
{\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}
\__expl_package_check:
%</package>
% \end{macrocode}
%
% A token list variable is a \TeX{} macro that holds tokens. By using the
% \eTeX{} primitive \tn{unexpanded} inside a \TeX{} \tn{edef} it is
% possible to store any tokens, including |#|, in this way.
%
% \subsection{Functions}
%
% \begin{macro}{\tl_new:N, \tl_new:c}
% Creating new token list variables is a case of checking for an
% existing definition and if free doing the definition.
% \begin{macrocode}
\cs_new_protected:Npn \tl_new:N #1
{
\__chk_if_free_cs:N #1
\cs_gset_eq:NN #1 \c_empty_tl
}
\cs_generate_variant:Nn \tl_new:N { c }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\tl_const:Nn, \tl_const:Nx, \tl_const:cn, \tl_const:cx}
% Constants are also easy to generate.
% \begin{macrocode}
\cs_new_protected:Npn \tl_const:Nn #1#2
{
\__chk_if_free_cs:N #1
\cs_gset_nopar:Npx #1 { \exp_not:n {#2} }
}
\cs_new_protected:Npn \tl_const:Nx #1#2
{
\__chk_if_free_cs:N #1
\cs_gset_nopar:Npx #1 {#2}
}
\cs_generate_variant:Nn \tl_const:Nn { c }
\cs_generate_variant:Nn \tl_const:Nx { c }
% \end{macrocode}
% \end{macro}
%
% \begin{variable}{\c_empty_tl}
% Never full. We need to define that constant early
% for \cs{tl_new:N} to work properly.
% \begin{macrocode}
\tl_const:Nn \c_empty_tl { }
% \end{macrocode}
% \end{variable}
%
% \begin{macro}{\tl_clear:N, \tl_clear:c}
% \begin{macro}{\tl_gclear:N, \tl_gclear:c}
% Clearing a token list variable means setting it to an empty value.
% Error checking will be sorted out by the parent function.
% \begin{macrocode}
\cs_new_protected:Npn \tl_clear:N #1
{ \tl_set_eq:NN #1 \c_empty_tl }
\cs_new_protected:Npn \tl_gclear:N #1
{ \tl_gset_eq:NN #1 \c_empty_tl }
\cs_generate_variant:Nn \tl_clear:N { c }
\cs_generate_variant:Nn \tl_gclear:N { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_clear_new:N, \tl_clear_new:c}
% \begin{macro}{\tl_gclear_new:N, \tl_gclear_new:c}
% Clearing a token list variable means setting it to an empty value.
% Error checking will be sorted out by the parent function.
% \begin{macrocode}
\cs_new_protected:Npn \tl_clear_new:N #1
{ \tl_if_exist:NTF #1 { \tl_clear:N #1 } { \tl_new:N #1 } }
\cs_new_protected:Npn \tl_gclear_new:N #1
{ \tl_if_exist:NTF #1 { \tl_gclear:N #1 } { \tl_new:N #1 } }
\cs_generate_variant:Nn \tl_clear_new:N { c }
\cs_generate_variant:Nn \tl_gclear_new:N { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_set_eq:NN, \tl_set_eq:Nc, \tl_set_eq:cN, \tl_set_eq:cc}
% \begin{macro}{\tl_gset_eq:NN, \tl_gset_eq:Nc, \tl_gset_eq:cN, \tl_gset_eq:cc}
% For setting token list variables equal to each other.
% \begin{macrocode}
\cs_new_eq:NN \tl_set_eq:NN \cs_set_eq:NN
\cs_new_eq:NN \tl_set_eq:cN \cs_set_eq:cN
\cs_new_eq:NN \tl_set_eq:Nc \cs_set_eq:Nc
\cs_new_eq:NN \tl_set_eq:cc \cs_set_eq:cc
\cs_new_eq:NN \tl_gset_eq:NN \cs_gset_eq:NN
\cs_new_eq:NN \tl_gset_eq:cN \cs_gset_eq:cN
\cs_new_eq:NN \tl_gset_eq:Nc \cs_gset_eq:Nc
\cs_new_eq:NN \tl_gset_eq:cc \cs_gset_eq:cc
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_concat:NNN, \tl_concat:ccc}
% \begin{macro}{\tl_gconcat:NNN, \tl_gconcat:ccc}
% Concatenating token lists is easy.
% \begin{macrocode}
\cs_new_protected:Npn \tl_concat:NNN #1#2#3
{ \tl_set:Nx #1 { \exp_not:o {#2} \exp_not:o {#3} } }
\cs_new_protected:Npn \tl_gconcat:NNN #1#2#3
{ \tl_gset:Nx #1 { \exp_not:o {#2} \exp_not:o {#3} } }
\cs_generate_variant:Nn \tl_concat:NNN { ccc }
\cs_generate_variant:Nn \tl_gconcat:NNN { ccc }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}[pTF]{\tl_if_exist:N, \tl_if_exist:c}
% Copies of the \texttt{cs} functions defined in \pkg{l3basics}.
% \begin{macrocode}
\cs_new_eq:NN \tl_if_exist:NTF \cs_if_exist:NTF
\cs_new_eq:NN \tl_if_exist:NT \cs_if_exist:NT
\cs_new_eq:NN \tl_if_exist:NF \cs_if_exist:NF
\cs_new_eq:NN \tl_if_exist_p:N \cs_if_exist_p:N
\cs_new_eq:NN \tl_if_exist:cTF \cs_if_exist:cTF
\cs_new_eq:NN \tl_if_exist:cT \cs_if_exist:cT
\cs_new_eq:NN \tl_if_exist:cF \cs_if_exist:cF
\cs_new_eq:NN \tl_if_exist_p:c \cs_if_exist_p:c
% \end{macrocode}
% \end{macro}
%
% \subsection{Constant token lists}
%
% \begin{variable}{\c_job_name_tl}
% Inherited from the \LaTeX3 name for the primitive: this needs to
% actually contain the text of the job name rather than the name of
% the primitive, of course. \LuaTeX{} does not quote file names containing
% spaces, whereas \pdfTeX{} and \XeTeX{} do. So there may be a correction to
% make in the \LuaTeX{} case.
% \begin{macrocode}
%<*initex>
\tex_everyjob:D \exp_after:wN
{
\tex_the:D \tex_everyjob:D
\luatex_if_engine:T
{
\lua_now:x
{ dofile ( assert ( kpse.find_file ("lualatexquotejobname.lua" ) ) ) }
}
}
%</initex>
\tl_const:Nx \c_job_name_tl { \tex_jobname:D }
% \end{macrocode}
% \end{variable}
%
% \begin{variable}{\c_space_tl}
% A space as a token list (as opposed to as a character).
% \begin{macrocode}
\tl_const:Nn \c_space_tl { ~ }
% \end{macrocode}
% \end{variable}
%
% \subsection{Adding to token list variables}
%
% \begin{macro}
% {
% \tl_set:Nn, \tl_set:NV, \tl_set:Nv, \tl_set:No, \tl_set:Nf, \tl_set:Nx,
% \tl_set:cn, \tl_set:NV, \tl_set:Nv, \tl_set:co, \tl_set:cf, \tl_set:cx
% }
% \begin{macro}
% {
% \tl_gset:Nn, \tl_gset:NV, \tl_gset:Nv,
% \tl_gset:No, \tl_gset:Nf, \tl_gset:Nx,
% \tl_gset:cn, \tl_gset:NV, \tl_gset:Nv,
% \tl_gset:co, \tl_gset:cf, \tl_gset:cx
% }
% By using \cs{exp_not:n} token list variables can contain |#| tokens,
% which makes the token list registers provided by \TeX{}
% more or less redundant. The \cs{tl_set:No} version is done
% \enquote{by hand} as it is used quite a lot.
% \begin{macrocode}
\cs_new_protected:Npn \tl_set:Nn #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:n {#2} } }
\cs_new_protected:Npn \tl_set:No #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:o {#2} } }
\cs_new_protected:Npn \tl_set:Nx #1#2
{ \cs_set_nopar:Npx #1 {#2} }
\cs_new_protected:Npn \tl_gset:Nn #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:n {#2} } }
\cs_new_protected:Npn \tl_gset:No #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:o {#2} } }
\cs_new_protected:Npn \tl_gset:Nx #1#2
{ \cs_gset_nopar:Npx #1 {#2} }
\cs_generate_variant:Nn \tl_set:Nn { NV , Nv , Nf }
\cs_generate_variant:Nn \tl_set:Nx { c }
\cs_generate_variant:Nn \tl_set:Nn { c, co , cV , cv , cf }
\cs_generate_variant:Nn \tl_gset:Nn { NV , Nv , Nf }
\cs_generate_variant:Nn \tl_gset:Nx { c }
\cs_generate_variant:Nn \tl_gset:Nn { c, co , cV , cv , cf }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}
% {
% \tl_put_left:Nn, \tl_put_left:NV, \tl_put_left:No, \tl_put_left:Nx,
% \tl_put_left:cn, \tl_put_left:cV, \tl_put_left:co, \tl_put_left:cx
% }
% \begin{macro}
% {
% \tl_gput_left:Nn, \tl_gput_left:NV, \tl_gput_left:No, \tl_gput_left:Nx,
% \tl_gput_left:cn, \tl_gput_left:cV, \tl_gput_left:co, \tl_gput_left:cx
% }
% Adding to the left is done directly to gain a little performance.
% \begin{macrocode}
\cs_new_protected:Npn \tl_put_left:Nn #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:n {#2} \exp_not:o #1 } }
\cs_new_protected:Npn \tl_put_left:NV #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:V #2 \exp_not:o #1 } }
\cs_new_protected:Npn \tl_put_left:No #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:o {#2} \exp_not:o #1 } }
\cs_new_protected:Npn \tl_put_left:Nx #1#2
{ \cs_set_nopar:Npx #1 { #2 \exp_not:o #1 } }
\cs_new_protected:Npn \tl_gput_left:Nn #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:n {#2} \exp_not:o #1 } }
\cs_new_protected:Npn \tl_gput_left:NV #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:V #2 \exp_not:o #1 } }
\cs_new_protected:Npn \tl_gput_left:No #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:o {#2} \exp_not:o #1 } }
\cs_new_protected:Npn \tl_gput_left:Nx #1#2
{ \cs_gset_nopar:Npx #1 { #2 \exp_not:o {#1} } }
\cs_generate_variant:Nn \tl_put_left:Nn { c }
\cs_generate_variant:Nn \tl_put_left:NV { c }
\cs_generate_variant:Nn \tl_put_left:No { c }
\cs_generate_variant:Nn \tl_put_left:Nx { c }
\cs_generate_variant:Nn \tl_gput_left:Nn { c }
\cs_generate_variant:Nn \tl_gput_left:NV { c }
\cs_generate_variant:Nn \tl_gput_left:No { c }
\cs_generate_variant:Nn \tl_gput_left:Nx { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}
% {
% \tl_put_right:Nn, \tl_put_right:NV, \tl_put_right:No, \tl_put_right:Nx,
% \tl_put_right:cn, \tl_put_right:cV, \tl_put_right:co, \tl_put_right:cx
% }
% \begin{macro}
% {
% \tl_gput_right:Nn, \tl_gput_right:NV, \tl_gput_right:No,
% \tl_gput_right:Nx,
% \tl_gput_right:cn, \tl_gput_right:cV, \tl_gput_right:co,
% \tl_gput_right:cx
% }
% The same on the right.
% \begin{macrocode}
\cs_new_protected:Npn \tl_put_right:Nn #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:o #1 \exp_not:n {#2} } }
\cs_new_protected:Npn \tl_put_right:NV #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:o #1 \exp_not:V #2 } }
\cs_new_protected:Npn \tl_put_right:No #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:o #1 \exp_not:o {#2} } }
\cs_new_protected:Npn \tl_put_right:Nx #1#2
{ \cs_set_nopar:Npx #1 { \exp_not:o #1 #2 } }
\cs_new_protected:Npn \tl_gput_right:Nn #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:o #1 \exp_not:n {#2} } }
\cs_new_protected:Npn \tl_gput_right:NV #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:o #1 \exp_not:V #2 } }
\cs_new_protected:Npn \tl_gput_right:No #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:o #1 \exp_not:o {#2} } }
\cs_new_protected:Npn \tl_gput_right:Nx #1#2
{ \cs_gset_nopar:Npx #1 { \exp_not:o {#1} #2 } }
\cs_generate_variant:Nn \tl_put_right:Nn { c }
\cs_generate_variant:Nn \tl_put_right:NV { c }
\cs_generate_variant:Nn \tl_put_right:No { c }
\cs_generate_variant:Nn \tl_put_right:Nx { c }
\cs_generate_variant:Nn \tl_gput_right:Nn { c }
\cs_generate_variant:Nn \tl_gput_right:NV { c }
\cs_generate_variant:Nn \tl_gput_right:No { c }
\cs_generate_variant:Nn \tl_gput_right:Nx { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \subsection{Reassigning token list category codes}
%
% \begin{variable}{\c_@@_rescan_marker_tl}
% The rescanning code needs a special token list containing the same
% character with two different category codes. This is set up here,
% while the detail is described below.
% \begin{macrocode}
\group_begin:
\tex_lccode:D `\A = `\@ \scan_stop:
\tex_lccode:D `\B = `\@ \scan_stop:
\tex_catcode:D `\A = 8 \scan_stop:
\tex_catcode:D `\B = 3 \scan_stop:
\tex_lowercase:D
{
\group_end:
\tl_const:Nn \c_@@_rescan_marker_tl { A B }
}
% \end{macrocode}
% \end{variable}
%
% \begin{macro}
% {
% \tl_set_rescan:Nnn, \tl_set_rescan:Nno, \tl_set_rescan:Nnx,
% \tl_set_rescan:cnn, \tl_set_rescan:cno, \tl_set_rescan:cnx
% }
% \begin{macro}
% {
% \tl_gset_rescan:Nnn, \tl_gset_rescan:Nno, \tl_gset_rescan:Nnx,
% \tl_gset_rescan:cnn, \tl_gset_rescan:cno, \tl_gset_rescan:cnx
% }
% \begin{macro}{\tl_rescan:nn}
% \begin{macro}[aux]{\@@_set_rescan:NNnn}
% \begin{macro}[aux]{\@@_rescan:w}
% The idea here is to deal cleanly with the problem that
% \tn{scantokens} treats the argument as a file, and without
% the correct settings a \TeX{} error occurs:
% \begin{verbatim}
% ! File ended while scanning definition of ...
% \end{verbatim}
% When expanding a token list this can be handled using \cs{exp_not:N}
% but this fails if the token list is not being expanded. So instead
% a delimited argument is used with an end marker which cannot appear
% within the token list which is scanned: two |@| symbols with different
% category codes. The rescanned token list cannot contain the end marker,
% because all |@| present in the token list are read with the same category
% code. As every character with charcode \tn{newlinechar} is replaced
% by the \tn{endlinechar}, and an extra \tn{endlinechar} is
% added at the end, we need to set both of those to $-1$,
% \enquote{unprintable}.
% \begin{macrocode}
\cs_new_protected_nopar:Npn \tl_set_rescan:Nnn
{ \@@_set_rescan:NNnn \tl_set:Nn }
\cs_new_protected_nopar:Npn \tl_gset_rescan:Nnn
{ \@@_set_rescan:NNnn \tl_gset:Nn }
\cs_new_protected_nopar:Npn \tl_rescan:nn
{ \@@_set_rescan:NNnn \prg_do_nothing: \use:n }
\cs_new_protected:Npn \@@_set_rescan:NNnn #1#2#3#4
{
\group_begin:
\exp_args:No \etex_everyeof:D { \c_@@_rescan_marker_tl \exp_not:N }
\tex_endlinechar:D \c_minus_one
\tex_newlinechar:D \c_minus_one
#3
\use:x
{
\group_end:
#1 \exp_not:N #2
{
\exp_after:wN \@@_rescan:w
\exp_after:wN \prg_do_nothing:
\etex_scantokens:D {#4}
}
}
}
\use:x
{
\cs_new:Npn \exp_not:N \@@_rescan:w ##1
\c_@@_rescan_marker_tl
{ \exp_not:N \exp_not:o { ##1 } }
}
\cs_generate_variant:Nn \tl_set_rescan:Nnn { Nno , Nnx }
\cs_generate_variant:Nn \tl_set_rescan:Nnn { c , cno , cnx }
\cs_generate_variant:Nn \tl_gset_rescan:Nnn { Nno , Nnx }
\cs_generate_variant:Nn \tl_gset_rescan:Nnn { c , cno }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \subsection{Reassigning token list character codes}
%
% \begin{macro}{\tl_to_lowercase:n}
% \begin{macro}{\tl_to_uppercase:n}
% Just some names for a few primitives.
% \begin{macrocode}
\cs_new_eq:NN \tl_to_lowercase:n \tex_lowercase:D
\cs_new_eq:NN \tl_to_uppercase:n \tex_uppercase:D
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \subsection{Modifying token list variables}
%
% \begin{macro}{\tl_replace_all:Nnn, \tl_replace_all:cnn}
% \begin{macro}{\tl_greplace_all:Nnn, \tl_greplace_all:cnn}
% \begin{macro}{\tl_replace_once:Nnn, \tl_replace_once:cnn}
% \begin{macro}{\tl_greplace_once:Nnn, \tl_greplace_once:cnn}
% \begin{macro}[aux]{\@@_replace:NNNnn, \@@_replace:w}
% \begin{macro}[aux]{\@@_replace_all:, \@@_replace_once:}
% \begin{macro}[aux]{\@@_replace_once_end:w}
% All of the replace functions are based on \cs{@@_replace:NNNnn},
% whose arguments are: \meta{function}, \cs{tl_(g)set:Nx}, \meta{tl~var},
% \meta{search tokens}, \meta{replacement tokens}.
% \begin{macrocode}
\cs_new_protected_nopar:Npn \tl_replace_once:Nnn
{ \@@_replace:NNNnn \@@_replace_once: \tl_set:Nx }
\cs_new_protected_nopar:Npn \tl_greplace_once:Nnn
{ \@@_replace:NNNnn \@@_replace_once: \tl_gset:Nx }
\cs_new_protected_nopar:Npn \tl_replace_all:Nnn
{ \@@_replace:NNNnn \@@_replace_all: \tl_set:Nx }
\cs_new_protected_nopar:Npn \tl_greplace_all:Nnn
{ \@@_replace:NNNnn \@@_replace_all: \tl_gset:Nx }
\cs_generate_variant:Nn \tl_replace_once:Nnn { c }
\cs_generate_variant:Nn \tl_greplace_once:Nnn { c }
\cs_generate_variant:Nn \tl_replace_all:Nnn { c }
\cs_generate_variant:Nn \tl_greplace_all:Nnn { c }
% \end{macrocode}
% The idea is easier to understand by considering the case of
% \cs{tl_replace_all:Nnn}. The replacement happens within an
% \texttt{x}-type expansion. We use an auxiliary function \cs{@@_tmp:w},
% which essentially replaces the next \meta{search tokens} by
% \meta{replacement tokens}. To avoid runaway arguments,
% we expand something like \cs{@@_tmp:w} \meta{token list} \cs{q_mark}
% \meta{search tokens} \cs{q_stop}, repeating until the end. How do we
% detect that we have reached the last occurrence of \meta{search tokens}?
% The last replacement is characterized by the fact that the argument of
% \cs{@@_tmp:w} contains \cs{q_mark}. In the code below,
% \cs{@@_replace:w} takes an argument delimited by \cs{q_mark},
% and removes the following token. Before we reach the end, this gobbles
% \cs{q_mark} \cs{use_none_delimit_by_q_stop:w} which appear in the
% definition of \cs{@@_tmp:w}, and leaves the \meta{replacement tokens},
% passed to \cs{exp_not:n}, to be included in the \texttt{x}-expanding
% definition. At the end, the first \cs{q_mark} is within the argument
% of \cs{@@_tmp:w}, and \cs{@@_replace:w} gobbles the second
% \cs{q_mark} as well, leaving \cs{use_none_delimit_by_q_stop:w},
% which ends the recursion cleanly.
% \begin{macrocode}
\cs_new_protected:Npn \@@_replace:NNNnn #1#2#3#4#5
{
\tl_if_empty:nTF {#4}
{
\__msg_kernel_error:nnx { kernel } { empty-search-pattern }
{ \tl_to_str:n {#5} }
}
{
\group_align_safe_begin:
\cs_set:Npx \@@_tmp:w ##1##2 #4
{
##2
\exp_not:N \q_mark
\exp_not:N \use_none_delimit_by_q_stop:w
\exp_not:n { \exp_not:n {#5} }
##1
}
\group_align_safe_end:
#2 #3
{
\exp_after:wN #1
#3 \q_mark #4 \q_stop
}
}
}
\cs_new:Npn \@@_replace:w #1 \q_mark #2 { \exp_not:o {#1} }
% \end{macrocode}
% The first argument of \cs{@@_tmp:w} is responsible for repeating
% the replacement in the case of \texttt{replace_all}, and stopping
% it early for \texttt{replace_once}. Note also that we build
% \cs{@@_tmp:w} within an \texttt{x}-expansion so that the
% \meta{replacement tokens} can contain |#|. The second
% \cs{exp_not:n} ensures that the \meta{replacement tokens}
% are not expanded by \cs{tl_(g)set:Nx}.
%
% Now on to the difference between \enquote{once} and \enquote{all}.
% The \cs{prg_do_nothing:} and accompanying \texttt{o}-expansion
% ensure that we don't lose braces in case the tokens between two
% occurrences of the \meta{search tokens} form a brace group.
% \begin{macrocode}
\cs_new_nopar:Npn \@@_replace_all:
{
\exp_after:wN \@@_replace:w
\@@_tmp:w \@@_replace_all: \prg_do_nothing:
}
\cs_new_nopar:Npn \@@_replace_once:
{
\exp_after:wN \@@_replace:w
\@@_tmp:w { \@@_replace_once_end:w \prg_do_nothing: } \prg_do_nothing:
}
\cs_new:Npn \@@_replace_once_end:w #1 \q_mark #2 \q_stop
{ \exp_not:o {#1} }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_remove_once:Nn, \tl_remove_once:cn}
% \begin{macro}{\tl_gremove_once:Nn, \tl_gremove_once:cn}
% Removal is just a special case of replacement.
% \begin{macrocode}
\cs_new_protected:Npn \tl_remove_once:Nn #1#2
{ \tl_replace_once:Nnn #1 {#2} { } }
\cs_new_protected:Npn \tl_gremove_once:Nn #1#2
{ \tl_greplace_once:Nnn #1 {#2} { } }
\cs_generate_variant:Nn \tl_remove_once:Nn { c }
\cs_generate_variant:Nn \tl_gremove_once:Nn { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_remove_all:Nn, \tl_remove_all:cn}
% \begin{macro}{\tl_gremove_all:Nn, \tl_gremove_all:cn}
% Removal is just a special case of replacement.
% \begin{macrocode}
\cs_new_protected:Npn \tl_remove_all:Nn #1#2
{ \tl_replace_all:Nnn #1 {#2} { } }
\cs_new_protected:Npn \tl_gremove_all:Nn #1#2
{ \tl_greplace_all:Nnn #1 {#2} { } }
\cs_generate_variant:Nn \tl_remove_all:Nn { c }
\cs_generate_variant:Nn \tl_gremove_all:Nn { c }
% \end{macrocode}
% \end{macro}
%
% \subsection{Token list conditionals}
%
% \begin{macro}[pTF]{\tl_if_blank:n,\tl_if_blank:V,\tl_if_blank:o}
% \begin{macro}[aux]{\@@_if_blank_p:NNw}
% \TeX{} skips spaces when reading a non-delimited arguments. Thus,
% a \meta{token list} is blank if and only if \cs{use_none:n}
% \meta{token list} |?| is empty. For performance reasons, we hard-code
% the emptyness test done in \cs{tl_if_empty:n(TF)}: convert to harmless
% characters with \cs{tl_to_str:n}, and then use
% \cs{if_meaning:w} \cs{q_nil} |...| \cs{q_nil}.
% Note that converting to a string is done after reading the delimited
% argument for \cs{use_none:n}. The similar construction
% \cs{exp_after:wN} \cs{use_none:n} \cs{tl_to_str:n} \Arg{token list} |?|
% would fail if the token list contains the control sequence \cs{ },
% while \tn{escapechar} is a space or is unprintable.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_blank:n #1 { p , T , F , TF }
{ \@@_if_empty_return:o { \use_none:n #1 ? } }
\cs_generate_variant:Nn \tl_if_blank_p:n { V }
\cs_generate_variant:Nn \tl_if_blank:nT { V }
\cs_generate_variant:Nn \tl_if_blank:nF { V }
\cs_generate_variant:Nn \tl_if_blank:nTF { V }
\cs_generate_variant:Nn \tl_if_blank_p:n { o }
\cs_generate_variant:Nn \tl_if_blank:nT { o }
\cs_generate_variant:Nn \tl_if_blank:nF { o }
\cs_generate_variant:Nn \tl_if_blank:nTF { o }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}[pTF]{\tl_if_empty:N,\tl_if_empty:c}
% These functions check whether the token list in the argument is
% empty and execute the proper code from their argument(s).
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_empty:N #1 { p , T , F , TF }
{
\if_meaning:w #1 \c_empty_tl
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
\cs_generate_variant:Nn \tl_if_empty_p:N { c }
\cs_generate_variant:Nn \tl_if_empty:NT { c }
\cs_generate_variant:Nn \tl_if_empty:NF { c }
\cs_generate_variant:Nn \tl_if_empty:NTF { c }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[pTF]{\tl_if_empty:n,\tl_if_empty:V}
% It would be tempting to just use |\if_meaning:w \q_nil #1 \q_nil| as
% a test since this works really well. However, it fails on a token
% list starting with \cs{q_nil} of course but more troubling is the
% case where argument is a complete conditional such as \cs{if_true:}
% a \cs{else:} b \cs{fi:} because then \cs{if_true:} is used by
% \cs{if_meaning:w}, the test turns out \texttt{false}, the \cs{else:}
% executes the \texttt{false} branch, the \cs{fi:} ends it and the
% \cs{q_nil} at the end
% starts executing\dots{} A safer route is to convert the entire
% token list into harmless characters first and then compare
% that. This way the test will even accept \cs{q_nil} as the first
% token.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_empty:n #1 { p , TF , T , F }
{
\exp_after:wN \if_meaning:w \exp_after:wN \q_nil \tl_to_str:n {#1} \q_nil
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
\cs_generate_variant:Nn \tl_if_empty_p:n { V }
\cs_generate_variant:Nn \tl_if_empty:nTF { V }
\cs_generate_variant:Nn \tl_if_empty:nT { V }
\cs_generate_variant:Nn \tl_if_empty:nF { V }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[pTF]{\tl_if_empty:o}
% \begin{macro}[EXP,aux]{\@@_if_empty_return:o}
% The auxiliary function \cs{@@_if_empty_return:o} is for use
% in conditionals on token lists, which mostly reduce to testing
% if a given token list is empty after applying a simple function
% to it.
% The test for emptiness is based on \cs{tl_if_empty:n(TF)}, but
% the expansion is hard-coded for efficiency, as this auxiliary
% function is used in many places.
% Note that this works because \cs{tl_to_str:n} expands tokens
% that follow until reading a catcode $1$ (begin-group) token.
% \begin{macrocode}
\cs_new:Npn \@@_if_empty_return:o #1
{
\exp_after:wN \if_meaning:w \exp_after:wN \q_nil
\tl_to_str:n \exp_after:wN {#1} \q_nil
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
\prg_new_conditional:Npnn \tl_if_empty:o #1 { p , TF , T , F }
{ \@@_if_empty_return:o {#1} }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}[pTF]{\tl_if_eq:NN, \tl_if_eq:Nc, \tl_if_eq:cN, \tl_if_eq:cc}
% Returns \cs{c_true_bool} if and only if the two token list variables are
% equal.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_eq:NN #1#2 { p , T , F , TF }
{
\if_meaning:w #1 #2
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
\cs_generate_variant:Nn \tl_if_eq_p:NN { Nc , c , cc }
\cs_generate_variant:Nn \tl_if_eq:NNTF { Nc , c , cc }
\cs_generate_variant:Nn \tl_if_eq:NNT { Nc , c , cc }
\cs_generate_variant:Nn \tl_if_eq:NNF { Nc , c , cc }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[TF]{\tl_if_eq:nn}
% \begin{variable}{\l_tl_internal_a_tl, \l_tl_internal_b_tl}
% A simple store and compare routine.
% \begin{macrocode}
\prg_new_protected_conditional:Npnn \tl_if_eq:nn #1#2 { T , F , TF }
{
\group_begin:
\tl_set:Nn \l_tl_internal_a_tl {#1}
\tl_set:Nn \l_tl_internal_b_tl {#2}
\if_meaning:w \l_tl_internal_a_tl \l_tl_internal_b_tl
\group_end:
\prg_return_true:
\else:
\group_end:
\prg_return_false:
\fi:
}
\tl_new:N \l_tl_internal_a_tl
\tl_new:N \l_tl_internal_b_tl
% \end{macrocode}
% \end{variable}
% \end{macro}
%
% \begin{macro}[TF]{\tl_if_in:Nn, \tl_if_in:cn}
% See \cs{tl_if_in:nn(TF)} for further comments. Here we simply
% expand the token list variable and pass it to \cs{tl_if_in:nn(TF)}.
% \begin{macrocode}
\cs_new_protected_nopar:Npn \tl_if_in:NnT { \exp_args:No \tl_if_in:nnT }
\cs_new_protected_nopar:Npn \tl_if_in:NnF { \exp_args:No \tl_if_in:nnF }
\cs_new_protected_nopar:Npn \tl_if_in:NnTF { \exp_args:No \tl_if_in:nnTF }
\cs_generate_variant:Nn \tl_if_in:NnT { c }
\cs_generate_variant:Nn \tl_if_in:NnF { c }
\cs_generate_variant:Nn \tl_if_in:NnTF { c }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[TF]{\tl_if_in:nn, \tl_if_in:Vn, \tl_if_in:on, \tl_if_in:no}
% Once more, the test relies on \cs{tl_to_str:n} for robustness.
% The function \cs{@@_tmp:w} removes tokens until the first occurrence
% of |#2|. If this does not appear in |#1|, then the final |#2| is removed,
% leaving an empty token list. Otherwise some tokens remain, and the
% test is \texttt{false}. See \cs{tl_if_empty:n(TF)} for details on
% the emptyness test.
%
% Special care is needed to treat correctly cases like
% |\tl_if_in:nnTF {a state}{states}|, where |#1#2| contains |#2| before
% the end. To cater for this case, we insert |{}{}| between the two token
% lists. This marker may not appear in |#2| because of \TeX{} limitations
% on what can delimit a parameter, hence we are safe. Using two brace
% groups makes the test work also for empty arguments.
% \begin{macrocode}
\prg_new_protected_conditional:Npnn \tl_if_in:nn #1#2 { T , F , TF }
{
\cs_set:Npn \@@_tmp:w ##1 #2 { }
\tl_if_empty:oTF { \@@_tmp:w #1 {} {} #2 }
{ \prg_return_false: } { \prg_return_true: }
}
\cs_generate_variant:Nn \tl_if_in:nnT { V , o , no }
\cs_generate_variant:Nn \tl_if_in:nnF { V , o , no }
\cs_generate_variant:Nn \tl_if_in:nnTF { V , o , no }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[EXP,pTF]{\tl_if_single:N}
% Expand the token list and feed it to \cs{tl_if_single:n}.
% \begin{macrocode}
\cs_new:Npn \tl_if_single_p:N { \exp_args:No \tl_if_single_p:n }
\cs_new:Npn \tl_if_single:NT { \exp_args:No \tl_if_single:nT }
\cs_new:Npn \tl_if_single:NF { \exp_args:No \tl_if_single:nF }
\cs_new:Npn \tl_if_single:NTF { \exp_args:No \tl_if_single:nTF }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[EXP,pTF]{\tl_if_single:n}
% A token list has exactly one item if it is either a single
% token surrounded by optional explicit spaces, or a single brace
% group surrounded by optional explicit spaces. The naive
% version of this test would do \cs{use_none:n} |#1|, and
% test if the result is empty. However, this will fail when
% the token list is empty. Furthermore, it does not allow optional
% trailing spaces.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_single:n #1 { p , T , F , TF }
{ \__str_if_eq_x_return:nn { \exp_not:o { \use_none:nn #1 ?? } } {?} }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[EXP]{\tl_case:Nnn, \tl_case:cnn}
% \begin{macro}[aux, EXP]{\@@_case:Nw}
% \begin{macro}[aux, EXP]{\@@_case_end:nw}
% \begin{macrocode}
\cs_new:Npn \tl_case:Nnn #1#2#3
{
\tex_romannumeral:D
\@@_case:Nw #1 #2 #1 {#3} \q_recursion_stop
}
\cs_new:Npn \@@_case:Nw #1#2#3
{
\tl_if_eq:NNTF #1 #2
{ \@@_case_end:nw {#3} }
{ \@@_case:Nw #1 }
}
\cs_generate_variant:Nn \tl_case:Nnn { c }
\cs_new_eq:NN \@@_case_end:nw \__prg_case_end:nw
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \subsection{Mapping to token lists}
%
% \begin{macro}{\tl_map_function:nN}
% \begin{macro}{\tl_map_function:NN, \tl_map_function:cN}
% \begin{macro}[aux]{\@@_map_function:Nn}
% Expandable loop macro for token lists. These have the advantage of not
% needing to test if the argument is empty, because if it is, the stop
% marker will be read immediately and the loop terminated.
% \begin{macrocode}
\cs_new:Npn \tl_map_function:nN #1#2
{
\@@_map_function:Nn #2 #1
\q_recursion_tail
\__prg_break_point:Nn \tl_map_break: { }
}
\cs_new_nopar:Npn \tl_map_function:NN
{ \exp_args:No \tl_map_function:nN }
\cs_new:Npn \@@_map_function:Nn #1#2
{
\__quark_if_recursion_tail_break:nN {#2} \tl_map_break:
#1 {#2} \@@_map_function:Nn #1
}
\cs_generate_variant:Nn \tl_map_function:NN { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_map_inline:nn}
% \begin{macro}{\tl_map_inline:Nn, \tl_map_inline:cn}
% The inline functions are straight forward by now. We use a little
% trick with the counter \cs{g__prg_map_int} to make
% them nestable. We can also make use of \cs{@@_map_function:Nn}
% from before.
% \begin{macrocode}
\cs_new_protected:Npn \tl_map_inline:nn #1#2
{
\int_gincr:N \g__prg_map_int
\cs_gset:cpn { __prg_map_ \int_use:N \g__prg_map_int :w } ##1 {#2}
\exp_args:Nc \@@_map_function:Nn
{ __prg_map_ \int_use:N \g__prg_map_int :w }
#1 \q_recursion_tail
\__prg_break_point:Nn \tl_map_break: { \int_gdecr:N \g__prg_map_int }
}
\cs_new_protected:Npn \tl_map_inline:Nn
{ \exp_args:No \tl_map_inline:nn }
\cs_generate_variant:Nn \tl_map_inline:Nn { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_map_variable:nNn}
% \begin{macro}{\tl_map_variable:NNn, \tl_map_variable:cNn}
% \begin{macro}[aux]{\@@_map_variable:Nnn}
% \cs{tl_map_variable:nNn} \meta{token list} \meta{temp} \meta{action}
% assigns
% \meta{temp} to each element and executes \meta{action}.
% \begin{macrocode}
\cs_new_protected:Npn \tl_map_variable:nNn #1#2#3
{
\@@_map_variable:Nnn #2 {#3} #1
\q_recursion_tail
\__prg_break_point:Nn \tl_map_break: { }
}
\cs_new_protected_nopar:Npn \tl_map_variable:NNn
{ \exp_args:No \tl_map_variable:nNn }
\cs_new_protected:Npn \@@_map_variable:Nnn #1#2#3
{
\tl_set:Nn #1 {#3}
\__quark_if_recursion_tail_break:NN #1 \tl_map_break:
\use:n {#2}
\@@_map_variable:Nnn #1 {#2}
}
\cs_generate_variant:Nn \tl_map_variable:NNn { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_map_break:}
% \begin{macro}{\tl_map_break:n}
% The break statements use the general \cs{__prg_map_break:Nn}.
% \begin{macrocode}
\cs_new_nopar:Npn \tl_map_break:
{ \__prg_map_break:Nn \tl_map_break: { } }
\cs_new_nopar:Npn \tl_map_break:n
{ \__prg_map_break:Nn \tl_map_break: }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \subsection{Using token lists}
%
% \begin{macro}{\tl_to_str:n}
% Another name for a primitive.
% \begin{macrocode}
\cs_new_eq:NN \tl_to_str:n \etex_detokenize:D
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\tl_to_str:N, \tl_to_str:c}
% These functions return the replacement text of a token list as a
% string.
% \begin{macrocode}
\cs_new:Npn \tl_to_str:N #1 { \etex_detokenize:D \exp_after:wN {#1} }
\cs_generate_variant:Nn \tl_to_str:N { c }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\tl_use:N, \tl_use:c}
% Token lists which are simply not defined will give a clear \TeX{}
% error here. No such luck for ones equal to \cs{scan_stop:} so
% instead a test is made and if there is an issue an error is forced.
% \begin{macrocode}
\cs_new:Npn \tl_use:N #1
{
\tl_if_exist:NTF #1 {#1}
{ \__msg_kernel_expandable_error:nnn { kernel } { bad-variable } {#1} }
}
\cs_generate_variant:Nn \tl_use:N { c }
% \end{macrocode}
% \end{macro}
%
% \subsection{Working with the contents of token lists}
%
% \begin{macro}{\tl_count:n, \tl_count:V, \tl_count:o}
% \begin{macro}{\tl_count:N, \tl_count:c}
% \begin{macro}[aux]{\@@_count:n}
% Count number of elements within a token list or token list
% variable. Brace groups within the list are read as a single
% element. Spaces are ignored.
% \cs{@@_count:n} grabs the element and replaces it by |+1|.
% The |0| to ensure it works on an empty list.
% \begin{macrocode}
\cs_new:Npn \tl_count:n #1
{
\int_eval:n
{ 0 \tl_map_function:nN {#1} \@@_count:n }
}
\cs_new:Npn \tl_count:N #1
{
\int_eval:n
{ 0 \tl_map_function:NN #1 \@@_count:n }
}
\cs_new:Npn \@@_count:n #1 { + \c_one }
\cs_generate_variant:Nn \tl_count:n { V , o }
\cs_generate_variant:Nn \tl_count:N { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_reverse_items:n}
% \begin{macro}[aux]{\@@_reverse_items:nwNwn}
% \begin{macro}[aux]{\@@_reverse_items:wn}
% Reversal of a token list is done by taking one item at a time
% and putting it after \cs{q_stop}.
% \begin{macrocode}
\cs_new:Npn \tl_reverse_items:n #1
{
\@@_reverse_items:nwNwn #1 ?
\q_mark \@@_reverse_items:nwNwn
\q_mark \@@_reverse_items:wn
\q_stop { }
}
\cs_new:Npn \@@_reverse_items:nwNwn #1 #2 \q_mark #3 #4 \q_stop #5
{
#3 #2
\q_mark \@@_reverse_items:nwNwn
\q_mark \@@_reverse_items:wn
\q_stop { {#1} #5 }
}
\cs_new:Npn \@@_reverse_items:wn #1 \q_stop #2
{ \exp_not:o { \use_none:nn #2 } }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_trim_spaces:n}
% \begin{macro}
% {
% \tl_trim_spaces:N, \tl_trim_spaces:c,
% \tl_gtrim_spaces:N, \tl_gtrim_spaces:c
% }
% Trimming spaces from around the input is deferred to an internal
% function whose first argument is the token list to trim, augmented
% by an initial \cs{q_mark}, and whose second argument is a
% \meta{continuation}, which will receive as a braced argument
% \cs{use_none:n} \cs{q_mark} \meta{trimmed token list}. In the case
% at hand, we take \cs{exp_not:o} as our continuation, so that space
% trimming will behave correctly within an \texttt{x}-type expansion.
% \begin{macrocode}
\cs_new:Npn \tl_trim_spaces:n #1
{ \@@_trim_spaces:nn { \q_mark #1 } \exp_not:o }
\cs_new_protected:Npn \tl_trim_spaces:N #1
{ \tl_set:Nx #1 { \exp_args:No \tl_trim_spaces:n {#1} } }
\cs_new_protected:Npn \tl_gtrim_spaces:N #1
{ \tl_gset:Nx #1 { \exp_args:No \tl_trim_spaces:n {#1} } }
\cs_generate_variant:Nn \tl_trim_spaces:N { c }
\cs_generate_variant:Nn \tl_gtrim_spaces:N { c }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}[int]{\@@_trim_spaces:nn}
% \begin{macro}[aux]
% {
% \@@_trim_spaces_i:w, \@@_trim_spaces_ii:w
% \@@_trim_spaces_iii:w, \@@_trim_spaces_iv:w
% }
% Trimming spaces from around the input is done using delimited
% arguments and quarks, and to get spaces at odd places in the
% definitions, we nest those in \cs{@@_tmp:w}, which then receives
% a single space as its argument: |#1| is \verb*+ +.
% Removing leading spaces is done with \cs{@@_trim_spaces_i:w},
% which loops until \cs{q_mark}\verb*+ + matches the end of the token
% list: then |##1| is the token list and |##3| is
% \cs{@@_trim_spaces_ii:w}. This hands the relevant tokens to the
% loop \cs{@@_trim_spaces_iii:w}, responsible for trimming
% trailing spaces. The end is reached when \verb*+ + \cs{q_nil}
% matches the one present in the definition of \cs{tl_trim_spacs:n}.
% Then \cs{@@_trim_spaces_iv:w} puts the token list into a group,
% with \cs{use_none:n} placed there to gobble a lingering \cs{q_mark},
% and feeds this to the \meta{continuation}.
% \begin{macrocode}
\cs_set:Npn \@@_tmp:w #1
{
\cs_new:Npn \@@_trim_spaces:nn ##1
{
\@@_trim_spaces_i:w
##1
\q_nil
\q_mark #1 { }
\q_mark \@@_trim_spaces_ii:w
\@@_trim_spaces_iii:w
#1 \q_nil
\@@_trim_spaces_iv:w
\q_stop
}
\cs_new:Npn \@@_trim_spaces_i:w ##1 \q_mark #1 ##2 \q_mark ##3
{
##3
\@@_trim_spaces_i:w
\q_mark
##2
\q_mark #1 {##1}
}
\cs_new:Npn \@@_trim_spaces_ii:w
\@@_trim_spaces_i:w \q_mark \q_mark ##1
{
\@@_trim_spaces_iii:w
##1
}
\cs_new:Npn \@@_trim_spaces_iii:w ##1 #1 \q_nil ##2
{
##2
##1 \q_nil
\@@_trim_spaces_iii:w
}
\cs_new:Npn \@@_trim_spaces_iv:w ##1 \q_nil ##2 \q_stop ##3
{ ##3 { \use_none:n ##1 } }
}
\@@_tmp:w { ~ }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \subsection{Token by token changes}
%
% \begin{variable}{\q__@@_act_mark,\q__@@_act_stop}
% The \cs{tl_act} functions may be applied to any token list.
% Hence, we use two private quarks, to allow any token, even quarks,
% in the token list.^^A in particular critical for future \::e.
% Only \cs{q__@@_act_mark} and \cs{q__@@_act_stop} may not appear
% in the token lists manipulated by \cs{@@_act:NNNnn} functions. The quarks
% are effectively defined in \pkg{l3quark}.
% \end{variable}
%
% \begin{macro}[EXP,int]{\@@_act:NNNnn}
% \begin{macro}[EXP,aux]{\@@_act_output:n, \@@_act_reverse_output:n}
% \begin{macro}[EXP,aux]{\@@_act_loop:w}
% \begin{macro}[EXP,aux]{\@@_act_normal:NwnNNN}
% \begin{macro}[EXP,aux]{\@@_act_group:nwnNNN}
% \begin{macro}[EXP,aux]{\@@_act_space:wwnNNN}
% \begin{macro}[EXP,aux]{\@@_act_end:w}
% To help control the expansion, \cs{@@_act:NNNnn} should always
% be proceeded by \tn{romannumeral} and ends by producing \cs{c_zero}
% once the result has been obtained. Then loop over tokens,
% groups, and spaces in |#5|. The marker \cs{q__@@_act_mark}
% is used both to avoid losing outer braces and to detect the
% end of the token list more easily. The result is stored
% as an argument for the dummy function \cs{@@_act_result:n}.
% \begin{macrocode}
\cs_new:Npn \@@_act:NNNnn #1#2#3#4#5
{
\group_align_safe_begin:
\@@_act_loop:w #5 \q__@@_act_mark \q__@@_act_stop
{#4} #1 #2 #3
\@@_act_result:n { }
}
% \end{macrocode}
% In the loop, we check how the token list begins and act
% accordingly. In the \enquote{normal} case, we may have
% reached \cs{q__@@_act_mark}, the end of the list. Then
% leave \cs{c_zero} and the result in the input stream,
% to terminate the expansion of \tn{romannumeral}.
% Otherwise, apply the relevant function to the
% \enquote{arguments}, |#3|
% and to the head of the token list. Then repeat the loop.
% The scheme is the same if the token list starts with a
% group or with a space. Some extra work is needed to
% make \cs{@@_act_space:wwnNNN} gobble the space.
% \begin{macrocode}
\cs_new:Npn \@@_act_loop:w #1 \q__@@_act_stop
{
\tl_if_head_is_N_type:nTF {#1}
{ \@@_act_normal:NwnNNN }
{
\tl_if_head_is_group:nTF {#1}
{ \@@_act_group:nwnNNN }
{ \@@_act_space:wwnNNN }
}
#1 \q__@@_act_stop
}
\cs_new:Npn \@@_act_normal:NwnNNN #1 #2 \q__@@_act_stop #3#4
{
\if_meaning:w \q__@@_act_mark #1
\exp_after:wN \@@_act_end:wn
\fi:
#4 {#3} #1
\@@_act_loop:w #2 \q__@@_act_stop
{#3} #4
}
\cs_new:Npn \@@_act_end:wn #1 \@@_act_result:n #2
{ \group_align_safe_end: \c_zero #2 }
\cs_new:Npn \@@_act_group:nwnNNN #1 #2 \q__@@_act_stop #3#4#5
{
#5 {#3} {#1}
\@@_act_loop:w #2 \q__@@_act_stop
{#3} #4 #5
}
\exp_last_unbraced:NNo
\cs_new:Npn \@@_act_space:wwnNNN \c_space_tl #1 \q__@@_act_stop #2#3#4#5
{
#5 {#2}
\@@_act_loop:w #1 \q__@@_act_stop
{#2} #3 #4 #5
}
% \end{macrocode}
% Typically, the output is done to the right of what was already output,
% using \cs{@@_act_output:n}, but for the \cs{@@_act_reverse} functions,
% it should be done to the left.
% \begin{macrocode}
\cs_new:Npn \@@_act_output:n #1 #2 \@@_act_result:n #3
{ #2 \@@_act_result:n { #3 #1 } }
\cs_new:Npn \@@_act_reverse_output:n #1 #2 \@@_act_result:n #3
{ #2 \@@_act_result:n { #1 #3 } }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}[EXP]{\tl_reverse:n, \tl_reverse:o, \tl_reverse:V}
% \begin{macro}[EXP,aux]{\@@_reverse_normal:nN}
% \begin{macro}[EXP,aux]{\@@_reverse_group_preserve:nn}
% \begin{macro}[EXP,aux]{\@@_reverse_space:n}
% The goal here is to reverse without losing spaces nor braces.
% This is done using the general internal function \cs{@@_act:NNNnn}.
% Spaces and \enquote{normal} tokens are output on the left of the current
% output. Grouped tokens are output to the left but without any reversal
% within the group. All of the internal functions here drop one argument:
% this is needed by \cs{@@_act:NNNnn} when changing case (to record
% which direction the change is in), but not when reversing the tokens.
% \begin{macrocode}
\cs_new:Npn \tl_reverse:n #1
{
\etex_unexpanded:D \exp_after:wN
{
\tex_romannumeral:D
\@@_act:NNNnn
\@@_reverse_normal:nN
\@@_reverse_group_preserve:nn
\@@_reverse_space:n
{ }
{#1}
}
}
\cs_generate_variant:Nn \tl_reverse:n { o , V }
\cs_new:Npn \@@_reverse_normal:nN #1#2
{ \@@_act_reverse_output:n {#2} }
\cs_new:Npn \@@_reverse_group_preserve:nn #1#2
{ \@@_act_reverse_output:n { {#2} } }
\cs_new:Npn \@@_reverse_space:n #1
{ \@@_act_reverse_output:n { ~ } }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_reverse:N, \tl_reverse:c, \tl_greverse:N, \tl_greverse:c}
% This reverses the list, leaving \cs{exp_stop_f:} in front,
% which stops the \texttt{f}-expansion.
% \begin{macrocode}
\cs_new_protected:Npn \tl_reverse:N #1
{ \tl_set:Nx #1 { \exp_args:No \tl_reverse:n { #1 } } }
\cs_new_protected:Npn \tl_greverse:N #1
{ \tl_gset:Nx #1 { \exp_args:No \tl_reverse:n { #1 } } }
\cs_generate_variant:Nn \tl_reverse:N { c }
\cs_generate_variant:Nn \tl_greverse:N { c }
% \end{macrocode}
% \end{macro}
%
% \subsection{The first token from a token list}
%
% \begin{macro}{\tl_head:N, \tl_head:n, \tl_head:V, \tl_head:v, \tl_head:f}
% \begin{macro}{\tl_head:w}
% \begin{macro}{\tl_tail:N, \tl_tail:n, \tl_tail:V, \tl_tail:v, \tl_tail:f}
% \begin{macro}{\tl_tail:w}
% \begin{macro}[aux]{\@@_tail:w}
% These functions pick up either the head or the tail of a list. The
% empty brace groups in \cs{tl_head:n} and \cs{tl_tail:n} ensure that
% a blank argument gives an empty result. The result is returned within
% the \tn{unexpanded} primitive.
% \begin{macrocode}
\cs_new:Npn \tl_head:w #1#2 \q_stop {#1}
\cs_new:Npn \tl_tail:w #1#2 \q_stop {#2}
\cs_new:Npn \tl_head:n #1
{ \etex_unexpanded:D \exp_after:wN { \tl_head:w #1 { } \q_stop } }
\cs_new:Npn \tl_tail:n #1
{ \etex_unexpanded:D \@@_tail:w #1 \q_mark { } \q_mark \q_stop }
\cs_new:Npn \@@_tail:w #1 #2 \q_mark #3 \q_stop { {#2} }
\cs_new_nopar:Npn \tl_head:N { \exp_args:No \tl_head:n }
\cs_generate_variant:Nn \tl_head:n { V , v , f }
\cs_new_nopar:Npn \tl_tail:N { \exp_args:No \tl_tail:n }
\cs_generate_variant:Nn \tl_tail:n { V , v , f }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\str_head:n, \str_tail:n}
% \begin{macro}[aux]{\__str_head:w}
% \begin{macro}[aux]{\__str_tail:w}
% After \cs{tl_to_str:n}, we have a list of character tokens,
% all with category code 12, except the space, which has category
% code 10. Directly using \cs{tl_head:w} would thus lose leading spaces.
% Instead, we take an argument delimited by an explicit space, and
% then only use \cs{tl_head:w}. If the string started with a
% space, then the argument of \cs{__str_head:w} is empty, and
% the function correctly returns a space character. Otherwise,
% it returns the first token of |#1|, which is the first token
% of the string. If the string is empty, we return an empty result.
%
% To remove the first character of \cs{tl_to_str:n} |{#1}|,
% we test it using \cs{if_charcode:w} \cs{scan_stop:},
% always \texttt{false} for characters. If the argument was non-empty,
% then \cs{__str_tail:w} returns everything until the first
% \texttt{X} (with category code letter, no risk of confusing
% with the user input). If the argument was empty, the first
% \texttt{X} is taken by \cs{if_charcode:w}, and nothing
% is returned. We use \texttt{X} as a \meta{marker}, rather than
% a quark because the test \cs{if_charcode:w} \cs{scan_stop:}
% \meta{marker} has to be \texttt{false}.
% \begin{macrocode}
\cs_new:Npn \str_head:n #1
{
\exp_after:wN \__str_head:w
\tl_to_str:n {#1}
{ { } } ~ \q_stop
}
\cs_new:Npn \__str_head:w #1 ~ %
{ \tl_head:w #1 { ~ } }
\cs_new:Npn \str_tail:n #1
{
\exp_after:wN \__str_tail:w
\reverse_if:N \if_charcode:w
\scan_stop: \tl_to_str:n {#1} X X \q_stop
}
\cs_new:Npn \__str_tail:w #1 X #2 \q_stop { \fi: #1 }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}[pTF]{\tl_if_head_eq_meaning:nN}
% \begin{macro}[pTF]{\tl_if_head_eq_charcode:nN}
% \begin{macro}[pTF]{\tl_if_head_eq_charcode:fN}
% \begin{macro}[pTF]{\tl_if_head_eq_catcode:nN}
% Accessing the first token of a token list is tricky in three cases:
% when it has category code $1$ (begin-group token), when it is an
% explicit space, with category code $10$ and character code $32$, or
% when the token list is empty (obviously).
%
% Forgetting temporarily about this issue we would use the following
% test in \cs{tl_if_head_eq_charcode:nN}. Here, \cs{tl_head:w} yields
% the first token of the token list, then passed to \cs{exp_not:N}.
% \begin{verbatim}
% \if_charcode:w
% \exp_after:wN \exp_not:N \tl_head:w #1 \q_nil \q_stop
% \exp_not:N #2
% \end{verbatim}
% The two first special cases are detected by testing if the token
% list starts with an \texttt{N}-type token (the extra |?| sends empty
% token lists to the \texttt{true} branch of this test). In those
% cases, the first token is a character, and since we only care about
% its character code, we can use \cs{str_head:n} to access it (this
% works even if it is a space character). An empty argument will
% result in \cs{tl_head:w} leaving two tokens: |?| which is taken in
% the \cs{if_charcode:w} test, and \cs{use_none:nn}, which ensures
% that \cs{prg_return_false:} is returned regardless of whether the
% charcode test was \texttt{true} or \texttt{false}.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_head_eq_charcode:nN #1#2 { p , T , F , TF }
{
\if_charcode:w
\exp_not:N #2
\tl_if_head_is_N_type:nTF { #1 ? }
{
\exp_after:wN \exp_not:N
\tl_head:w #1 { ? \use_none:nn } \q_stop
}
{ \str_head:n {#1} }
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
\cs_generate_variant:Nn \tl_if_head_eq_charcode_p:nN { f }
\cs_generate_variant:Nn \tl_if_head_eq_charcode:nNTF { f }
\cs_generate_variant:Nn \tl_if_head_eq_charcode:nNT { f }
\cs_generate_variant:Nn \tl_if_head_eq_charcode:nNF { f }
% \end{macrocode}
% For \cs{tl_if_head_eq_catcode:nN}, again we detect special cases
% with a \cs{tl_if_head_is_N_type:n}. Then we need to test if the
% first token is a begin-group token or an explicit space token, and
% produce the relevant token, either \cs{c_group_begin_token} or
% \cs{c_space_token}. Again, for an empty argument, a hack is used,
% removing \cs{prg_return_true:} and \cs{else:} with \cs{use_none:nn}
% in case the catcode test with the (arbitrarily chosen) |?| is
% \texttt{true}.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_head_eq_catcode:nN #1 #2 { p , T , F , TF }
{
\if_catcode:w
\exp_not:N #2
\tl_if_head_is_N_type:nTF { #1 ? }
{
\exp_after:wN \exp_not:N
\tl_head:w #1 { ? \use_none:nn } \q_stop
}
{
\tl_if_head_is_group:nTF {#1}
{ \c_group_begin_token }
{ \c_space_token }
}
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
% \end{macrocode}
% For \cs{tl_if_head_eq_meaning:nN}, again, detect special cases. In
% the normal case, use \cs{tl_head:w}, with no \cs{exp_not:N} this
% time, since \cs{if_meaning:w} causes no expansion. With an empty
% argument, the test is \texttt{true}, and \cs{use_none:nnn} removes
% |#2| and the usual \cs{prg_return_true:} and \cs{else:}.
% In the special cases, we know that the first token is a character,
% hence \cs{if_charcode:w} and \cs{if_catcode:w} together are enough.
% We combine them in some order, hopefully faster than the reverse.
% Tests are not nested because the arguments may contain unmatched
% primitive conditionals.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_head_eq_meaning:nN #1#2 { p , T , F , TF }
{
\tl_if_head_is_N_type:nTF { #1 ? }
{ \@@_if_head_eq_meaning_normal:nN }
{ \@@_if_head_eq_meaning_special:nN }
{#1} #2
}
\cs_new:Npn \@@_if_head_eq_meaning_normal:nN #1 #2
{
\exp_after:wN \if_meaning:w
\tl_head:w #1 { ?? \use_none:nnn } \q_stop #2
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
\cs_new:Npn \@@_if_head_eq_meaning_special:nN #1 #2
{
\if_charcode:w \str_head:n {#1} \exp_not:N #2
\exp_after:wN \use:n
\else:
\prg_return_false:
\exp_after:wN \use_none:n
\fi:
{
\if_catcode:w \exp_not:N #2
\tl_if_head_is_group:nTF {#1}
{ \c_group_begin_token }
{ \c_space_token }
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}[pTF]{\tl_if_head_is_N_type:n}
% The first token of a token list can be either an N-type argument,
% a begin-group token (catcode 1), or an explicit space token
% (catcode 10 and charcode 32). These two cases are characterized
% by the fact that \cs{use:n} removes some tokens from |#1|, hence
% changing its string representation (no token can have an empty
% string representation). The extra brace group covers the case of
% an empty argument, whose head is not \enquote{normal}.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_head_is_N_type:n #1 { p , T , F , TF }
{
\__str_if_eq_x_return:nn
{ \exp_not:o { \use:n #1 { } } }
{ \exp_not:n { #1 { } } }
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[EXP,pTF]{\tl_if_head_is_group:n}
% Pass the first token of |#1| through \cs{token_to_str:N},
% then check for the brace balance. The extra \texttt{?}
% caters for an empty argument.\footnote{Bruno: this could
% be made faster, but we don't: if we hope to ever have
% an e-type argument, we need all brace \enquote{tricks}
% to happen in one step of expansion, keeping the token
% list brace balanced at all times.}
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_head_is_group:n #1 { p , T , F , TF }
{
\if_catcode:w *
\exp_after:wN \use_none:n
\exp_after:wN {
\exp_after:wN {
\token_to_str:N #1 ?
}
}
*
\prg_return_false:
\else:
\prg_return_true:
\fi:
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[EXP,pTF]{\tl_if_head_is_space:n}
% \begin{macro}[EXP,aux]{\@@_if_head_is_space:w}
% If the first token of the token list is an explicit space, i.e.,
% a character token with character code $32$ and category code $10$,
% then this test will be \texttt{true}. It is \texttt{false} if the token
% list is empty, if the first token is an implicit space token,
% such as \cs{c_space_token}, or any token other than an explicit space.
% The slightly convoluted approach with \tn{romannumeral} ensures that
% each expansion step gives a balanced token list.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_head_is_space:n #1 { p , T , F , TF }
{
\tex_romannumeral:D \if_false: { \fi:
\@@_if_head_is_space:w ? #1 ? ~ }
}
\cs_new:Npn \@@_if_head_is_space:w #1 ~
{
\tl_if_empty:oTF { \use_none:n #1 }
{ \exp_after:wN \c_zero \exp_after:wN \prg_return_true: }
{ \exp_after:wN \c_zero \exp_after:wN \prg_return_false: }
\exp_after:wN \use_none:n \exp_after:wN { \if_false: } \fi:
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \subsection{Viewing token lists}
%
% \begin{macro}{\tl_show:N, \tl_show:c}
% Showing token list variables is done directly: at the moment do not
% worry if they are defined.
% \begin{macrocode}
\cs_new_protected:Npn \tl_show:N #1 { \cs_show:N #1 }
\cs_generate_variant:Nn \tl_show:N { c }
% \end{macrocode}
%\end{macro}
%
% \begin{macro}{\tl_show:n}
% For literal token lists, life is easy.
% \begin{macrocode}
\cs_new_eq:NN \tl_show:n \etex_showtokens:D
% \end{macrocode}
%\end{macro}
%
% \subsection{Scratch token lists}
%
% \begin{variable}{\g_tmpa_tl, \g_tmpb_tl}
% Global temporary token list variables.
% They are supposed to be set and used immediately,
% with no delay between the definition and the use because you
% can't count on other macros not to redefine them from under you.
% \begin{macrocode}
\tl_new:N \g_tmpa_tl
\tl_new:N \g_tmpb_tl
% \end{macrocode}
% \end{variable}
%
% \begin{variable}{\l_tmpa_tl, \l_tmpb_tl}
% These are local temporary token list variables. Be sure not to assume
% that the value you put into them will survive for
% long---see discussion above.
% \begin{macrocode}
\tl_new:N \l_tmpa_tl
\tl_new:N \l_tmpb_tl
% \end{macrocode}
% \end{variable}
%
% \subsection{Deprecated functions}
%
% \begin{macro}{\tl_new:Nn, \tl_new:cn, \tl_new:Nx}
% Use either \cs{tl_const:Nn} or \cs{tl_new:N}.
% \begin{macrocode}
%<*deprecated>
\cs_new_protected:Npn \tl_new:Nn #1#2
{
\tl_new:N #1
\tl_gset:Nn #1 {#2}
}
\cs_generate_variant:Nn \tl_new:Nn { c }
\cs_generate_variant:Nn \tl_new:Nn { Nx }
%</deprecated>
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\tl_gset:Nc}
% \begin{macro}{\tl_set:Nc}
% This was useful once, but nowadays does not make much sense.
% \begin{macrocode}
%<*deprecated>
\cs_new_protected_nopar:Npn \tl_gset:Nc
{ \tex_global:D \tl_set:Nc }
\cs_new_protected:Npn \tl_set:Nc #1#2
{ \tl_set:No #1 { \cs:w #2 \cs_end: } }
%</deprecated>
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_replace_in:Nnn, \tl_replace_in:cnn}
% \begin{macro}{\tl_greplace_in:Nnn, \tl_greplace_in:cnn}
% \begin{macro}{\tl_replace_all_in:Nnn, \tl_replace_all_in:cnn}
% \begin{macro}{\tl_greplace_all_in:Nnn, \tl_greplace_all_in:cnn}
% These are renamed.
% \begin{macrocode}
%<*deprecated>
\cs_new_eq:NN \tl_replace_in:Nnn \tl_replace_once:Nnn
\cs_new_eq:NN \tl_replace_in:cnn \tl_replace_once:cnn
\cs_new_eq:NN \tl_greplace_in:Nnn \tl_greplace_once:Nnn
\cs_new_eq:NN \tl_greplace_in:cnn \tl_greplace_once:cnn
\cs_new_eq:NN \tl_replace_all_in:Nnn \tl_replace_all:Nnn
\cs_new_eq:NN \tl_replace_all_in:cnn \tl_replace_all:cnn
\cs_new_eq:NN \tl_greplace_all_in:Nnn \tl_greplace_all:Nnn
\cs_new_eq:NN \tl_greplace_all_in:cnn \tl_greplace_all:cnn
%</deprecated>
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_remove_in:Nn, \tl_remove_in:cn}
% \begin{macro}{\tl_gremove_in:Nn, \tl_gremove_in:cn}
% \begin{macro}{\tl_remove_all_in:Nn, \tl_remove_all_in:cn}
% \begin{macro}{\tl_gremove_all_in:Nn, \tl_gremove_all_in:cn}
% Also renamed.
% \begin{macrocode}
%<*deprecated>
\cs_new_eq:NN \tl_remove_in:Nn \tl_remove_once:Nn
\cs_new_eq:NN \tl_remove_in:cn \tl_remove_once:cn
\cs_new_eq:NN \tl_gremove_in:Nn \tl_gremove_once:Nn
\cs_new_eq:NN \tl_gremove_in:cn \tl_gremove_once:cn
\cs_new_eq:NN \tl_remove_all_in:Nn \tl_remove_all:Nn
\cs_new_eq:NN \tl_remove_all_in:cn \tl_remove_all:cn
\cs_new_eq:NN \tl_gremove_all_in:Nn \tl_gremove_all:Nn
\cs_new_eq:NN \tl_gremove_all_in:cn \tl_gremove_all:cn
%</deprecated>
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_elt_count:n, \tl_elt_count:V, \tl_elt_count:o}
% \begin{macro}{\tl_elt_count:N, \tl_elt_count:c}
% Another renaming job.
% \begin{macrocode}
%<*deprecated>
\cs_new_eq:NN \tl_elt_count:n \tl_count:n
\cs_new_eq:NN \tl_elt_count:V \tl_count:V
\cs_new_eq:NN \tl_elt_count:o \tl_count:o
\cs_new_eq:NN \tl_elt_count:N \tl_count:N
\cs_new_eq:NN \tl_elt_count:c \tl_count:c
%</deprecated>
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\tl_head_i:n}
% \begin{macro}{\tl_head_i:w}
% \begin{macro}{\tl_head_iii:n}
% \begin{macro}{\tl_head_iii:f}
% \begin{macro}{\tl_head_iii:w}
% Two renames, and a few that are rather too specialised.
% \begin{macrocode}
%<*deprecated>
\cs_new_eq:NN \tl_head_i:n \tl_head:n
\cs_new_eq:NN \tl_head_i:w \tl_head:w
\cs_new:Npn \tl_head_iii:n #1 { \tl_head_iii:w #1 \q_stop }
\cs_generate_variant:Nn \tl_head_iii:n { f }
\cs_new:Npn \tl_head_iii:w #1#2#3#4 \q_stop {#1#2#3}
%</deprecated>
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% Deprecated on 2012-05-13 for removal by 2012-08-31.
%
% \begin{macro}{\tl_length_tokens:n}
% \begin{macrocode}
\cs_new_eq:NN \tl_length_tokens:n \tl_count_tokens:n
% \end{macrocode}
% \end{macro}
%
% Deprecated 2012-05-13 for removal by 2012-11-31.
%
% \begin{macro}
% {\tl_length:N, \tl_length:c, \tl_length:n, \tl_length:V, \tl_length:o}
% Renames.
% \begin{macrocode}
\cs_new_eq:NN \tl_length:N \tl_count:N
\cs_new_eq:NN \tl_length:c \tl_count:c
\cs_new_eq:NN \tl_length:n \tl_count:n
\cs_new_eq:NN \tl_length:V \tl_count:V
\cs_new_eq:NN \tl_length:o \tl_count:o
% \end{macrocode}
% \end{macro}
%
% Deprecated 2012-06-05 for removal after 2012-12-31.
%
% \begin{macro}[pTF]{\tl_if_empty:x}
% We can test expandably the emptiness of an expanded token list
% thanks to the primitive \tn{pdfstrcmp} which expands its argument:
% a token list is empty if and only if its string representation is
% empty.
% \begin{macrocode}
\prg_new_conditional:Npnn \tl_if_empty:x #1 { p , T , F , TF }
{ \__str_if_eq_x_return:nn { } {#1} }
% \end{macrocode}
% \end{macro}
%
% Deprecated 2012-07-08 for removal after 2012-10-31.
%
% \begin{macro}[EXP, pTF]{\tl_if_head_group:n}
% \begin{macro}[EXP, pTF]{\tl_if_head_N_type:n}
% \begin{macro}[EXP, pTF]{\tl_if_head_space:n}
% \begin{macrocode}
\prg_new_eq_conditional:NNn \tl_if_head_group:n \tl_if_head_is_group:n
{ p , T , F , TF }
\prg_new_eq_conditional:NNn \tl_if_head_N_type:n \tl_if_head_is_N_type:n
{ p , T , F , TF }
\prg_new_eq_conditional:NNn \tl_if_head_space:n \tl_if_head_is_space:n
{ p , T , F , TF }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</initex|package>
% \end{macrocode}
%
% \end{implementation}
%
% \PrintIndex
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