/
l3text.dtx
2931 lines (2931 loc) · 89.8 KB
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l3text.dtx
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% \iffalse meta-comment
%
%% File: l3text.dtx
%
% Copyright (C) 2019 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
%
% https://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 development version of the bundle can be found at
%
% https://github.com/latex3/latex3
%
% for those people who are interested.
%
%<*driver>
\documentclass[full,kernel]{l3doc}
\begin{document}
\DocInput{\jobname.dtx}
\end{document}
%</driver>
% \fi
%
%
% \title{^^A
% The \textsf{l3text} package: text processing^^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 2019-11-07}
%
% \maketitle
%
% \begin{documentation}
%
% \section{\pkg{l3text} documentation}
%
% This module deals with manipulation of (formatted) text; such material is
% comprised of a restricted set of token list content. The functions provided
% here concern conversion of textual content for example in case changing,
% generation of bookmarks and extraction to tags.
%
% \begin{function}[EXP, added = 2019-11-20]{\text_expand:n}
% \begin{syntax}
% \cs{text_expand:n} \Arg{text}
% \end{syntax}
% Takes user input \meta{text} and transforms expandable and implicit
% content to the explicit equivalent. Protected commands (typically
% formatting) are left in place, and no processing takes place of
% math mode material (as delimited by pairs given in
% \cs{l_text_math_delims_tl} or as the argument to commands listed
% in \cs{l_text_math_arg_tl}). Commands which are neither engine-
% nor \LaTeX{} protected are expanded exhaustively. Implicit tokens,
% including implicit groups, are converted to their explicit equivalent.
% The argument to any command listed in \cs{l_text_exclude_arg_tl} are
% excluded from expansion. Any commands listed in \cs{l_text_accents_tl}
% and \cs{l_text_letterlike_tl} are excluded from expansion.
% \end{function}
%
% \begin{function}[EXP, added = 2019-11-20]
% {
% \text_lowercase:n, \text_uppercase:n, \text_titlecase:n,
% \text_titlecase_first:n,
% \text_lowercase:nn, \text_uppercase:nn, \text_titlecase:nn,
% \text_titlecase_first:nn
% }
% \begin{syntax}
% \cs{text_uppercase:n} \Arg{tokens}
% \cs{text_uppercase:nn} \Arg{language} \Arg{tokens}
% \end{syntax}
% Takes user input \meta{text} first applies \cs{text_expand}, then
% transforms the case of character tokens as specified by the
% function name. The category code of letters are not changed by this
% process (at least where they can be represented by the engine as a single
% token: $8$-bit engines may require active characters).
%
% Upper- and lowercase have the obvious meanings. Titlecasing may be regarded
% informally as converting the first character of the \meta{tokens} to
% uppercase and the rest to lowercase. However, the process is more complex
% than this as there are some situations where a single lower case character
% maps to a special form, for example \texttt{ij} in Dutch which becomes
% \texttt{IJ}. The \texttt{titlecase_first} variant does not attempt
% any case changing at all after the first letter has been processed.
%
% Importantly, notice that these functions are intended for working with
% user \emph{text for typesetting}. For case changing programmatic data see
% the \pkg{l3str} module and discussion there of \cs{str_lowercase:n},
% \cs{str_uppercase:n} and \cs{str_foldcase:n}.
%
% Case changing does not take place within math mode material so for example
% \begin{verbatim}
% \text_uppercase:n { Some~text~$y = mx + c$~with~{Braces} }
% \end{verbatim}
% becomes
% \begin{verbatim}
% SOME TEXT $y = mx + c$ WITH {BRACES}
% \end{verbatim}
%
% The arguments of commands listed in \cs{l_text_case_exclude_arg_tl}
% and \cs{l_text_exclude_arg_tl} are exlcuded from case changing; the
% latter are entirely non-textual content (such as labels).
%
% As is generally true for \pkg{expl3}, these functions are designed to
% work with Unicode input only. As such, UTF-8 input is assumed for
% \emph{all} engines. When used with \XeTeX{} or \LuaTeX{} a full range of
% Unicode transformations are enabled. Specifically, the standard mappings
% here follow those defined by the \href{http://www.unicode.org}^^A
% {Unicode Consortium} in \texttt{UnicodeData.txt} and
% \texttt{SpecialCasing.txt}. In the case of $8$-bit engines, mappings
% are provided for characters which can be represented in output typeset
% using the |T1| font encoding. Thus for example \texttt{ä} can be
% case-changed using \pdfTeX{}. For \pTeX{} only the ASCII range is
% covered as the engine treats input outside of this range as east Asian.
%
% Language-sensitive conversions are enabled using the \meta{language}
% argument, and follow Unicode Consortium guidelines. Currently, the
% languages recognised for special handling are as follows.
% \begin{itemize}
% \item Azeri and Turkish (\texttt{az} and \texttt{tr}).
% The case pairs I/i-dotless and I-dot/i are activated for these
% languages. The combining dot mark is removed when lowercasing
% I-dot and introduced when upper casing i-dotless.
% \item German (\texttt{de-alt}).
% An alternative mapping for German in which the lowercase
% \emph{Eszett} maps to a \emph{gro\ss{}es Eszett}.
% \item Greek (\texttt{el}).
% Removes accents from Greek letters when uppercasing; titlecasing
% leaves accents in place.
% \item Lithuanian (\texttt{lt}).
% The lowercase letters i and j should retain a dot above when the
% accents grave, acute or tilde are present. This is implemented for
% lowercasing of the relevant uppercase letters both when input as
% single Unicode codepoints and when using combining accents. The
% combining dot is removed when uppercasing in these cases. Note that
% \emph{only} the accents used in Lithuanian are covered: the behaviour
% of other accents are not modified.
% \item Dutch (\texttt{nl}).
% Capitalisation of \texttt{ij} at the beginning of titlecased
% input produces \texttt{IJ} rather than \texttt{Ij}. The output
% retains two separate letters, thus this transformation \emph{is}
% available using \pdfTeX{}.
% \end{itemize}
% \end{function}
%
% \begin{function}[rEXP, added = 2019-12-05]{\text_purify:n}
% \begin{syntax}
% \cs{text_purify:n} \Arg{text}
% \end{syntax}
% Takes user input \meta{text} and expands as described for
% \cs{text_expand:n}, then removes all functions from the resulting
% text. No processing takes place of math mode material (as delimited by
% pairs given in \cs{l_text_math_delims_tl} or as the argument to commands
% listed in \cs{l_text_math_arg_tl}); these tokens and functions are left
% in-place. Non-expandable functions present in the \meta{text} must either
% have a defined equivalent (see \cs{text_declare_purify_equivalent:Nn})
% or will be removed from the result.
% \end{function}
%
% \begin{function}[added = 2019-12-05]
% {
% \text_declare_purify_equivalent:Nn ,
% \text_declare_purify_equivalent:Nx
% }
% \begin{syntax}
% \cs{text_declare_purify_equivalent:Nn} \meta{cmd} \Arg{replacement}
% \end{syntax}
% Declares that the \meta{replacement} tokens should be used whenever the
% \meta{cmd} (a single token) is encountered. The \meta{replacement} tokens
% should be expandable.
% \end{function}
%
% \begin{variable}{\l_text_accents_tl}
% Lists commands which represent accents, and which are left unchanged
% by expansion.
% \end{variable}
%
% \begin{variable}{\l_text_case_exclude_arg_tl}
% Lists commands present in the \meta{text} where the argument of the
% command should be excluded from case changing.
% \end{variable}
%
% \begin{variable}{\l_text_exclude_arg_tl}
% Lists commands present in the \meta{text} where the argument of the
% command should be excluded from expansion, etc. The argument is regarded
% as non-textual by all functions in the module: depending on the treatment
% of non-text, the command and its argument may be left unchanged, or
% removed entirely.
% \end{variable}
%
% \begin{variable}{\l_text_letterlike_tl}
% Lists commands which represent letters; these are left unchanged by
% expansion.
% \end{variable}
%
% \begin{variable}{\l_text_math_arg_tl}
% Lists commands present in the \meta{text} where the argument of the
% command should be treated as math mode material. The treatment here is
% similar to \cs{l_text_math_delims_tl} but for a command rather than
% paired delimiters.
% \end{variable}
%
% \begin{variable}{\l_text_math_delims_tl}
% Lists pairs of tokens which delimit (in-line) math mode content; such
% content \emph{may} be excluded from processing.
% \end{variable}
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3text} implementation}
%
% \begin{macrocode}
%<*initex|package>
% \end{macrocode}
%
% \begin{macrocode}
%<@@=text>
% \end{macrocode}
%
% \subsection{Utilities}
%
% \begin{macro}[EXP]
% {
% \@@_token_to_explicit:N ,
% \@@_token_to_explicit_char:N ,
% \@@_token_to_explicit_cs:N ,
% \@@_token_to_explicit_cs_aux:N
% }
% \begin{macro}[EXP]{\@@_token_to_explicit:n}
% \begin{macro}[EXP]
% {
% \@@_token_to_explicit_auxi:w ,
% \@@_token_to_explicit_auxii:w ,
% \@@_token_to_explicit_auxiii:w
% }
% The idea here is to take a token and ensure that if it's an implicit
% char, we output the explicit version. Otherwise, the token needs to be
% unchanged. First, we have to split between control sequences and everything
% else.
% \begin{macrocode}
\group_begin:
\char_set_catcode_active:n { 0 }
\cs_new:Npn \@@_token_to_explicit:N #1
{
\if_catcode:w \exp_not:N #1
\if_catcode:w \scan_stop: \exp_not:N #1
\scan_stop:
\else:
\exp_not:N ^^@
\fi:
\exp_after:wN \@@_token_to_explicit_cs:N
\else:
\exp_after:wN \@@_token_to_explicit_char:N
\fi:
#1
}
\group_end:
% \end{macrocode}
% For control sequences, we can check for macros versus other cases using
% \cs{if_meaning:w}, then explicitly check for \tn{chardef} and
% \tn{mathchardef}.
% \begin{macrocode}
\cs_new:Npn \@@_token_to_explicit_cs:N #1
{
\exp_after:wN \if_meaning:w \exp_not:N #1 #1
\exp_after:wN \use:nn \exp_after:wN
\@@_token_to_explicit_cs_aux:N
\else:
\exp_after:wN \exp_not:n
\fi:
{#1}
}
\cs_new:Npn \@@_token_to_explicit_cs_aux:N #1
{
\bool_lazy_or:nnTF
{ \token_if_chardef_p:N #1 }
{ \token_if_mathchardef_p:N #1 }
{
\char_generate:nn {#1}
{ \char_value_catcode:n {#1} }
}
{#1}
}
% \end{macrocode}
% For character tokens, we need to filter out the implicit characters from
% those that are explicit. That's done here, then if necessary we work out
% the category code and generate the char. To avoid issues with alignment
% tabs, that one is done by elimination rather than looking up the code
% explicitly. The trick with finding the charcode is that the \TeX{}
% messages are either \texttt{the \meta{something} character \meta{char}}
% or \texttt{the \meta{type} \meta{char}}.
% \begin{macrocode}
\cs_new:Npn \@@_token_to_explicit_char:N #1
{
\if:w
\if_catcode:w ^ \exp_args:No \str_tail:n { \token_to_str:N #1 } ^
\token_to_str:N #1 #1
\else:
AB
\fi:
\exp_after:wN \exp_not:n
\else:
\exp_after:wN \@@_token_to_explicit:n
\fi:
{#1}
}
\cs_new:Npn \@@_token_to_explicit:n #1
{
\exp_after:wN \@@_token_to_explicit_auxi:w
\int_value:w
\if_catcode:w \c_group_begin_token #1 1 \else:
\if_catcode:w \c_group_end_token #1 2 \else:
\if_catcode:w \c_math_toggle_token #1 3 \else:
\if_catcode:w ## #1 6 \else:
\if_catcode:w ^ #1 7 \else:
\if_catcode:w \c_math_subscript_token #1 8 \else:
\if_catcode:w \c_space_token #1 10 \else:
\if_catcode:w A #1 11 \else:
\if_catcode:w + #1 12 \else:
4 \fi: \fi: \fi: \fi: \fi: \fi: \fi: \fi: \fi:
\exp_after:wN ;
\token_to_meaning:N #1 \q_stop
}
\cs_new:Npn \@@_token_to_explicit_auxi:w #1 ; #2 \q_stop
{
\char_generate:nn
{
\if_int_compare:w #1 < 9 \exp_stop_f:
\exp_after:wN \@@_token_to_explicit_auxii:w
\else:
\exp_after:wN \@@_token_to_explicit_auxiii:w
\fi:
#2
}
{#1}
}
\exp_last_unbraced:NNNNo \cs_new:Npn \@@_token_to_explicit_auxii:w
#1 { \tl_to_str:n { character ~ } } { ` }
\cs_new:Npn \@@_token_to_explicit_auxiii:w #1 ~ #2 ~ { ` }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}[EXP]{\@@_char_catcode:N}
% An idea from \pkg{l3char}: we need to get the category code of
% a specific token, not the general case.
% \begin{macrocode}
\cs_new:Npn \@@_char_catcode:N #1
{
\if_catcode:w \exp_not:N #1 \c_math_toggle_token
3
\else:
\if_catcode:w \exp_not:N #1 \c_alignment_token
4
\else:
\if_catcode:w \exp_not:N #1 \c_math_superscript_token
7
\else:
\if_catcode:w \exp_not:N #1 \c_math_subscript_token
8
\else:
\if_catcode:w \exp_not:N #1 \c_space_token
10
\else:
\if_catcode:w \exp_not:N #1 \c_catcode_letter_token
11
\else:
\if_catcode:w \exp_not:N #1 \c_catcode_other_token
12
\else:
13
\fi:
\fi:
\fi:
\fi:
\fi:
\fi:
\fi:
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}[EXP, TF]{\@@_if_expandable:N}
% Test for tokens that make sense to expand here: that is more
% restrictive than the engine view.
% \begin{macrocode}
\prg_new_conditional:Npnn \@@_if_expandable:N #1 { T , F , TF }
{
\token_if_expandable:NTF #1
{
\bool_lazy_any:nTF
{
{ \token_if_protected_macro_p:N #1 }
{ \token_if_protected_long_macro_p:N #1 }
{ \token_if_eq_meaning_p:NN \q_recursion_tail #1 }
}
{ \prg_return_false: }
{ \prg_return_true: }
}
{ \prg_return_false: }
}
% \end{macrocode}
% \end{macro}
%
% \subsection{Configuration variables}
%
% \begin{variable}{\l_text_accents_tl, \l_text_letterlike_tl}
% Special cases for accents and letter-like symbols, which in some cases will
% need to be converted further.
% \begin{macrocode}
\tl_new:N \l_text_accents_tl
\tl_set:Nn \l_text_accents_tl
{ \` \' \^ \~ \= \u \. \" \r \H \v \d \c \k \b \t }
\tl_new:N \l_text_letterlike_tl
\tl_set:Nn \l_text_letterlike_tl
{
\AA \aa
\AE \ae
\DH \dh
\DJ \dj
\IJ \ij
\L \l
\NG \ng
\O \o
\OE \oe
\SS \ss
\TH \th
}
% \end{macrocode}
% \end{variable}
%
% \begin{variable}{\l_text_case_exclude_arg_tl}
% Excluded specifically from case changing.
% \begin{macrocode}
\tl_new:N \l_text_case_exclude_arg_tl
% \end{macrocode}
% \end{variable}
%
% \begin{variable}{\l_text_exclude_arg_tl}
% Non-textual arguments.
% \begin{macrocode}
\tl_new:N \l_text_exclude_arg_tl
\tl_set:Nn \l_text_exclude_arg_tl { \cite \label \ref }
% \end{macrocode}
% \end{variable}
%
% \begin{variable}{\l_text_math_arg_tl}
% Math mode as arguments.
% \begin{macrocode}
\tl_new:N \l_text_math_arg_tl
\tl_set:Nn \l_text_math_arg_tl { \ensuremath }
% \end{macrocode}
% \end{variable}
%
% \begin{variable}{\l_text_math_delims_tl}
% Paired math mode delimiters.
% \begin{macrocode}
\tl_new:N \l_text_math_delims_tl
\tl_set:Nn \l_text_math_delims_tl { $ $ \( \) }
% \end{macrocode}
% \end{variable}
%
% \subsection{Expansion to formatted text}
%
% \begin{variable}{\c_@@_chardef_space_token, \c_@@_mathchardef_space_token}
% \begin{variable}
% {\c_@@_chardef_group_begin_token, \c_@@_mathchardef_group_begin_token}
% \begin{variable}
% {\c_@@_chardef_group_end_token, \c_@@_mathchardef_group_end_token}
% Markers for implict char handling.
% \begin{macrocode}
\tex_chardef:D \c_@@_chardef_space_token = `\ %
\tex_mathchardef:D \c_@@_mathchardef_space_token = `\ %
\tex_chardef:D \c_@@_chardef_group_begin_token = `\{ % `\}
\tex_mathchardef:D \c_@@_mathchardef_group_begin_token = `\{ % `\} `\{
\tex_chardef:D \c_@@_chardef_group_end_token = `\} % `\{
\tex_mathchardef:D \c_@@_mathchardef_group_end_token = `\} %
% \end{macrocode}
% \end{variable}
% \end{variable}
% \end{variable}
%
% \begin{macro}[EXP]{\text_expand:n, \@@_expand:n}
% \begin{macro}[EXP]{\@@_expand_result:n}
% \begin{macro}[EXP]{\@@_expand_store:n, \@@_expand_store:o}
% \begin{macro}[EXP]{\@@_expand_store:nw}
% \begin{macro}[EXP]{\@@_expand_end:w}
% \begin{macro}[EXP]{\@@_expand_loop:w}
% \begin{macro}[EXP]{\@@_expand_group:n}
% \begin{macro}[EXP]{\@@_expand_space:w}
% \begin{macro}[EXP]
% {
% \@@_expand_N_type:N ,
% \@@_expand_N_type_auxi:N ,
% \@@_expand_N_type_auxii:N ,
% \@@_expand_N_type_auxiii:N
% }
% \begin{macro}[EXP]{\@@_expand_math_search:NNN}
% \begin{macro}[EXP]{\@@_expand_math_loop:Nw}
% \begin{macro}[EXP]{\@@_expand_math_N_type:NN}
% \begin{macro}[EXP]{\@@_expand_math_group:Nn}
% \begin{macro}[EXP]{\@@_expand_math_space:Nw}
% \begin{macro}[EXP]{\@@_expand_exclude:N}
% \begin{macro}[EXP]{\@@_expand_exclude:nN}
% \begin{macro}[EXP]{\@@_expand_exclude:NN}
% \begin{macro}[EXP]{\@@_expand_exclude:Nn}
% \begin{macro}[EXP]{\@@_expand_letterlike:N}
% \begin{macro}[EXP]{\@@_expand_letterlike:NN}
% \begin{macro}[EXP]
% {
% \@@_expand_implicit:N ,
% \@@_expand_explicit:N ,
% \@@_expand_cs:N ,
% \@@_expand_protect:N
% }
% \begin{macro}[EXP]{\@@_expand_protect:nN}
% \begin{macro}[EXP]{\@@_expand_protect:Nw}
% \begin{macro}[EXP]{\@@_expand_cs_expand:N}
% After precautions against |&| tokens, start a simple loop: that of
% course means that \enquote{text} cannot contain the two recursion
% quarks. The loop here must be \texttt{f}-type expandable; we have
% arbitrary user commands which might be protected \emph{and} take
% arguments, and if the expansion code is used in a typesetting
% context, that will otherwise explode. (The same issue applies more
% clearly to case changing: see the example there.)
% \begin{macrocode}
\cs_new:Npn \text_expand:n #1
{
\__kernel_exp_not:w \exp_after:wN
{
\exp:w
\@@_expand:n {#1}
}
}
\cs_new:Npn \@@_expand:n #1
{
\group_align_safe_begin:
\@@_expand_loop:w #1
\q_recursion_tail \q_recursion_stop
\@@_expand_result:n { }
}
% \end{macrocode}
% The approach to making the code \texttt{f}-type expandable is to usee
% a marker result token and to shuffle the collected tokens
% \begin{macrocode}
\cs_new:Npn \@@_expand_store:n #1
{ \@@_expand_store:nw {#1} }
\cs_generate_variant:Nn \@@_expand_store:n { o }
\cs_new:Npn \@@_expand_store:nw #1#2 \@@_expand_result:n #3
{ #2 \@@_expand_result:n { #3 #1 } }
\cs_new:Npn \@@_expand_end:w #1 \@@_expand_result:n #2
{
\group_align_safe_end:
\exp_end:
#2
}
% \end{macrocode}
% The main loop is a standard \enquote{tl action}; groups are handled
% recursively, while spaces are just passed through. Thus all of the
% action is in handling \texttt{N}-type tokens.
% \begin{macrocode}
\cs_new:Npn \@@_expand_loop:w #1 \q_recursion_stop
{
\tl_if_head_is_N_type:nTF {#1}
{ \@@_expand_N_type:N }
{
\tl_if_head_is_group:nTF {#1}
{ \@@_expand_group:n }
{ \@@_expand_space:w }
}
#1 \q_recursion_stop
}
\cs_new:Npn \@@_expand_group:n #1
{
\@@_expand_store:o
{
\exp_after:wN
{
\exp:w
\@@_expand:n {#1}
}
}
\@@_expand_loop:w
}
\exp_last_unbraced:NNo \cs_new:Npn \@@_expand_space:w \c_space_tl
{
\@@_expand_store:n { ~ }
\@@_expand_loop:w
}
% \end{macrocode}
% Before we get into the real work, we have to watch out for problematic
% implicit characters: spaces and grouping tokens. Converting these to
% explicit characters later would lead to real issues as they are \emph{not}
% \texttt{N}-type. A space is the easy case, so it's dealt with first:
% just insert the explicit token and continue the loop.
% \begin{macrocode}
\cs_new:Npx \@@_expand_N_type:N #1
{
\exp_not:N \quark_if_recursion_tail_stop_do:Nn #1
{ \exp_not:N \@@_expand_end:w }
\exp_not:N \bool_lazy_any:nTF
{
{ \exp_not:N \token_if_eq_meaning_p:NN #1 \c_space_token }
{
\exp_not:N \token_if_eq_meaning_p:NN #1
\c_@@_chardef_space_token
}
{
\exp_not:N \token_if_eq_meaning_p:NN #1
\c_@@_mathchardef_space_token
}
}
{ \exp_not:N \@@_expand_space:w \c_space_tl }
{ \exp_not:N \@@_expand_N_type_auxi:N #1 }
}
% \end{macrocode}
% Implicit |{|/|}| offer two issues. First, the token could be an implicit
% brace character: we need to avoid turning that into a brace group, so filter
% out the cases manually. Then we handle the case where an implicit group is
% present. That is done in an \enquote{open-ended} way: there's the possibility
% the closing token is hidden somewhere.
% \begin{macrocode}
\cs_new:Npn \@@_expand_N_type_auxi:N #1
{
\bool_lazy_or:nnTF
{ \token_if_eq_meaning_p:NN #1 \c_@@_chardef_group_begin_token }
{ \token_if_eq_meaning_p:NN #1 \c_@@_mathchardef_group_begin_token }
{
\@@_expand_store:o \c_left_brace_str
\@@_expand_loop:w
}
{
\bool_lazy_or:nnTF
{ \token_if_eq_meaning_p:NN #1 \c_@@_chardef_group_end_token }
{ \token_if_eq_meaning_p:NN #1 \c_@@_mathchardef_group_end_token }
{
\@@_expand_store:o \c_right_brace_str
\@@_expand_loop:w
}
{ \@@_expand_N_type_auxii:N #1 }
}
}
\cs_new:Npn \@@_expand_N_type_auxii:N #1
{
\token_if_eq_meaning:NNTF #1 \c_group_begin_token
{
{ \if_false: } \fi:
\@@_expand_loop:w
}
{
\token_if_eq_meaning:NNTF #1 \c_group_end_token
{
\if_false: { \fi: }
\@@_expand_loop:w
}
{ \@@_expand_N_type_auxiii:N #1 }
}
}
% \end{macrocode}
% The first step in dealing with \texttt{N}-type tokens is to look for
% math mode material: that needs to be left alone. The starting function
% has to be split into two as we need \cs{quark_if_recursion_tail_stop:N}
% first before we can trigger the search. We then look for matching
% pairs of delimiters, allowing for the case where math mode starts
% but does not end. Within math mode, we simply pass all the tokens
% through unchanged, just checking the \texttt{N}-type ones against the
% end marker.
% \begin{macrocode}
\cs_new:Npn \@@_expand_N_type_auxiii:N #1
{
\exp_after:wN \@@_expand_math_search:NNN
\exp_after:wN #1 \l_text_math_delims_tl
\q_recursion_tail \q_recursion_tail
\q_recursion_stop
}
\cs_new:Npn \@@_expand_math_search:NNN #1#2#3
{
\quark_if_recursion_tail_stop_do:Nn #2
{ \@@_expand_exclude:N #1 }
\token_if_eq_meaning:NNTF #1 #2
{
\use_i_delimit_by_q_recursion_stop:nw
{
\@@_expand_store:n {#1}
\@@_expand_math_loop:Nw #3
}
}
{ \@@_expand_math_search:NNN #1 }
}
\cs_new:Npn \@@_expand_math_loop:Nw #1#2 \q_recursion_stop
{
\tl_if_head_is_N_type:nTF {#2}
{ \@@_expand_math_N_type:NN }
{
\tl_if_head_is_group:nTF {#2}
{ \@@_expand_math_group:Nn }
{ \@@_expand_math_space:Nw }
}
#1#2 \q_recursion_stop
}
\cs_new:Npn \@@_expand_math_N_type:NN #1#2
{
\quark_if_recursion_tail_stop_do:Nn #2
{ \@@_expand_end:w }
\@@_expand_store:n {#2}
\token_if_eq_meaning:NNTF #2 #1
{ \@@_expand_loop:w }
{ \@@_expand_math_loop:Nw #1 }
}
\cs_new:Npn \@@_expand_math_group:Nn #1#2
{
\@@_expand_store:n { {#2} }
\@@_expand_math_loop:Nw #1
}
\exp_after:wN \cs_new:Npn \exp_after:wN \@@_expand_math_space:Nw
\exp_after:wN # \exp_after:wN 1 \c_space_tl
{
\@@_expand_store:n { ~ }
\@@_expand_math_loop:Nw #1
}
% \end{macrocode}
% Next we exclude any commands with one argument that are explicitly
% listed. This is mainly as there \emph{might} be an \cs{ensuremath},
% but one never knows about for example accents in labels too. We also deal
% with accents here: they are effectively the same situation.
% \begin{macrocode}
\cs_new:Npn \@@_expand_exclude:N #1
{
\exp_args:Ne \@@_expand_exclude:nN
{
\exp_not:V \l_text_exclude_arg_tl
\exp_not:V \l_text_math_arg_tl
\exp_not:V \l_text_accents_tl
}
#1
}
\cs_new:Npn \@@_expand_exclude:nN #1#2
{
\@@_expand_exclude:NN #2 #1
\q_recursion_tail \q_recursion_stop
}
\cs_new:Npn \@@_expand_exclude:NN #1#2
{
\quark_if_recursion_tail_stop_do:Nn #2
{ \@@_expand_letterlike:N #1 }
\cs_if_eq:NNTF #2 #1
{
\use_i_delimit_by_q_recursion_stop:nw
{ \@@_expand_exclude:Nn #1 }
}
{ \@@_expand_exclude:NN #1 }
}
\cs_new:Npn \@@_expand_exclude:Nn #1#2
{
\@@_expand_store:n { #1 {#2} }
\@@_expand_loop:w
}
% \end{macrocode}
% Another list of exceptions: these ones take no arguments so are
% easier to handle.
% \begin{macrocode}
\cs_new:Npn \@@_expand_letterlike:N #1
{
\exp_after:wN \@@_expand_letterlike:NN \exp_after:wN
#1 \l_text_letterlike_tl
\q_recursion_tail \q_recursion_stop
}
\cs_new:Npn \@@_expand_letterlike:NN #1#2
{
\quark_if_recursion_tail_stop_do:Nn #2
{ \@@_expand_implicit:N #1 }
\cs_if_eq:NNTF #2 #1
{
\use_i_delimit_by_q_recursion_stop:nw
{
\@@_expand_store:n {#1}
\@@_expand_loop:w
}
}
{ \@@_expand_letterlike:NN #1 }
}
% \end{macrocode}
% Conversion of implicit to explicit tokens does not have to account for
% spaces or brace groups: they are already fixed above. So we can assume that
% the result of this conversion is still an \texttt{N}-type token.
% \begin{macrocode}
\cs_new:Npn \@@_expand_implicit:N #1
{
\exp_args:NNe \use:nn \@@_expand_explicit:N
{ \@@_token_to_explicit:N #1 }
}
% \end{macrocode}
% At this stage, either we have a control sequence or a simple character:
% split and handle.
% \begin{macrocode}
\cs_new:Npn \@@_expand_explicit:N #1
{
\token_if_cs:NTF #1
{ \@@_expand_cs:N #1 }
{
\@@_expand_store:n {#1}
\@@_expand_loop:w
}
}
% \end{macrocode}
% \LaTeXe{}'s \cs{protect} makes life interesting. Where possible, we
% simply remove it and replace with the \enquote{parent} command; of course,
% the \cs{protect} might be explicit, in which case we need to leave it alone
% if it's required.
% \begin{macrocode}
\cs_new:Npn \@@_expand_cs:N #1
{
\str_if_eq:nnTF {#1} { \protect }
{ \@@_expand_protect:N }
{ \@@_expand_cs_expand:N #1 }
}
\cs_new:Npn \@@_expand_protect:N #1
{
\exp_args:Ne \@@_expand_protect:nN
{ \cs_to_str:N #1 } #1
}
\cs_new:Npn \@@_expand_protect:nN #1#2
{ \@@_expand_protect:Nw #2 #1 \q_nil #1 ~ \q_nil \q_nil \q_stop }
\cs_new:Npn \@@_expand_protect:Nw #1 #2 ~ \q_nil #3 \q_nil #4 \q_stop
{
\quark_if_nil:nTF {#4}
{
\cs_if_exist:cTF {#2}
{ \exp_args:Ne \@@_expand_store:n { \exp_not:c {#2} } }
{ \@@_expand_store:n { \protect #1 } }
}
{ \@@_expand_store:n { \protect #1 } }
\@@_expand_loop:w
}
% \end{macrocode}
% Finally, expand any macros which can be: this then loops back around to
% deal with what they produce.
% \begin{macrocode}
\cs_new:Npn \@@_expand_cs_expand:N #1
{
\@@_if_expandable:NTF #1
{ \exp_after:wN \@@_expand_loop:w #1 }
{
\@@_expand_store:n {#1}
\@@_expand_loop:w
}
}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \subsection{Case changing}
%
% \begin{macro}[EXP]
% {
% \text_lowercase:n,
% \text_uppercase:n,
% \text_titlecase:n,
% \text_titlecase_first:n
% }
% \begin{macro}[EXP]
% {
% \text_lowercase:nn,
% \text_uppercase:nn,
% \text_titlecase:nn,
% \text_titlecase_first:nn
% }
% The user level functions here are all wrappers around the internal
% functions for case changing.
% \begin{macrocode}
\cs_new:Npn \text_lowercase:n #1
{ \@@_change_case:nnn { lower } { } {#1} }
\cs_new:Npn \text_uppercase:n #1
{ \@@_change_case:nnn { upper } { } {#1} }
\cs_new:Npn \text_titlecase:n #1
{ \@@_change_case:nnn { title } { } {#1} }
\cs_new:Npn \text_titlecase_first:n #1
{ \@@_change_case:nnn { titleonly } { } {#1} }
\cs_new:Npn \text_lowercase:nn #1#2
{ \@@_change_case:nnn { lower } {#1} {#2} }
\cs_new:Npn \text_uppercase:nn #1#2
{ \@@_change_case:nnn { upper } {#1} {#2} }
\cs_new:Npn \text_titlecase:nn #1#2
{ \@@_change_case:nnn { title } {#1} {#2} }
\cs_new:Npn \text_titlecase_first:nn #1#2
{ \@@_change_case:nnn { titleonly } {#1} {#2} }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}[EXP]{\@@_change_case:nnn, \@@_change_case_aux:nnn}
% \begin{macro}[EXP]{\@@_change_case_store:n}
% \begin{macro}[EXP]{\@@_change_case_store:nw}
% \begin{macro}[EXP]{\@@_change_case_result:n}
% \begin{macro}[EXP]{\@@_change_case_end:w}
% \begin{macro}[EXP]{\@@_change_case_loop:nnw}
% \begin{macro}[EXP]{\@@_change_case_break:w}
% \begin{macro}[EXP]
% {
% \@@_change_case_group_lower:nnn ,
% \@@_change_case_group_upper:nnn ,
% \@@_change_case_group_title:nnn ,
% \@@_change_case_group_titleonly:nnn
% }
% \begin{macro}[EXP]{\@@_change_case_space:nnw}
% \begin{macro}[EXP]{\@@_change_case_N_type:nnN, \@@_change_case_N_type_aux:nnN}
% \begin{macro}[EXP]{\@@_change_case_N_type:nnnN}
% \begin{macro}[EXP]{\@@_change_case_math_search:nnNNN}
% \begin{macro}[EXP]{\@@_change_case_math_loop:nnNw}
% \begin{macro}[EXP]{\@@_change_case_math_N_type:nnNN}
% \begin{macro}[EXP]{\@@_change_case_math_group:nnNn}
% \begin{macro}[EXP]{\@@_change_case_math_space:nnNw}
% \begin{macro}[EXP]{\@@_change_case_cs_check:nnN}
% \begin{macro}[EXP]{\@@_change_case_exclude:nnN}
% \begin{macro}[EXP]{\@@_change_case_exclude:nnnN}
% \begin{macro}[EXP]{\@@_change_case_exclude:nnNN}
% \begin{macro}[EXP]{\@@_change_case_exclude:nnNn}
% \begin{macro}[EXP]
% {
% \@@_change_case_letterlike_lower:nnN ,
% \@@_change_case_letterlike_upper:nnN ,
% \@@_change_case_letterlike_title:nnN ,
% \@@_change_case_letterlike_titleonly:nnN
% }
% \begin{macro}[EXP]{\@@_change_case_letterlike:nnnnN}
% \begin{macro}[EXP]
% {\@@_change_case_char_lower:nnN, \@@_change_case_char_upper:nnN}
% \begin{macro}[EXP]{\@@_change_case_lower_sigma:nnnN}
% \begin{macro}[EXP]{\@@_change_case_lower_sigma:nnNw}
% \begin{macro}[EXP]{\@@_change_case_lower_sigma:NnnN}
% \begin{macro}[EXP]
% {\@@_change_case_char_title:nnN, \@@_change_case_char_titleonly:nnN}
% \begin{macro}[EXP]
% {\@@_change_case_char_title:nN, \@@_change_case_char_titleonly:nN}
% \begin{macro}[EXP]{\@@_change_case_char_title:nnnN}
% \begin{macro}[EXP]{\@@_change_case_char_char:nnnN}
% \begin{macro}[EXP]{\@@_change_case_char_UTFviii:nnnNN}
% \begin{macro}[EXP]{\@@_change_case_char_UTFviii:nnnNNN}
% \begin{macro}[EXP]{\@@_change_case_char_UTFviii:nnnNNNNN}
% \begin{macro}[EXP]{\@@_change_case_char_UTFviii:nnnn}
% \begin{macro}[EXP]
% {
% \@@_change_case_char_next_lower:nn ,
% \@@_change_case_char_next_upper:nn ,
% \@@_change_case_char_next_title:nn ,
% \@@_change_case_char_next_titleonly:nn
% }
% \begin{macro}[EXP]{\@@_change_case_char_next_end:nn}
% As for the expansion code, the business end of case changing is the
% handling of \texttt{N}-type tokens. First, we expand the input fully
% (so the loops here don't need to worry about awkward look-aheads and the
% like). Then we split into the different paths.
%
% The code here needs to be \texttt{f}-type expandable to deal with the
% situation where case changing is applied in running text. There, we
% might have case changing as a document command and the text containing
% other non-expandable document commands.
% \begin{verbatim}
% \cs_set_eq:NN \MakeLowercase \text_lowercase