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+% \iffalse meta-comment
+%
+% Copyright (C) 1999 Frank Mittelbach, Chris Rowley, David Carlisle
+% Copyright (C) 2004-2008 Frank Mittelbach, The LaTeX3 Project
+% Copyright (C) 2009-2021
+% The LaTeX Project and any individual authors listed elsewhere
+% in this file.
+%
+% This file is part of the LaTeX base system.
+% -------------------------------------------
+%
+% It may be distributed and/or modified under the
+% conditions of the LaTeX Project Public License, either version 1.3c
+% of this license or (at your option) any later version.
+% The latest version of this license is in
+% https://www.latex-project.org/lppl.txt
+% and version 1.3c or later is part of all distributions of LaTeX
+% version 2008 or later.
+%
+% This file has the LPPL maintenance status "maintained".
+%
+% The list of all files belonging to the LaTeX base distribution is
+% given in the file `manifest.txt'. See also `legal.txt' for additional
+% information.
+%
+% The list of derived (unpacked) files belonging to the distribution
+% and covered by LPPL is defined by the unpacking scripts (with
+% extension .ins) which are part of the distribution.
+%
+% \fi
+%
+% \iffalse
+%
+%%% From File: ltcmd.dtx
+%
+% \begin{macrocode}
+\def\ltcmdversion{v1.0e}
+\def\ltcmddate{2021-05-24}
+% \end{macrocode}
+%
+%<*driver>
+% \fi
+\ProvidesFile{ltcmd.dtx}
+ [\ltcmddate\space \ltcmdversion\space
+ LaTeX Kernel (Document commands)]
+% \iffalse
+\documentclass{l3doc}
+\GetFileInfo{ltcmd.dtx}
+\title{\filename}
+\date{\filedate}
+\author{Frank Mittelbach, Chris Rowley, David Carlisle, \LaTeX{} Project Team}
+\begin{document}
+ \maketitle
+ \DocInput{ltcmd.dtx}
+\end{document}
+%</driver>
+% \fi
+%
+% \section{Creating document commands}
+%
+% \changes{v1.0a}{2020/11/20}{Initial version derived from \texttt{xparse.dtx}}
+%
+% Document commands should be created using the tools provided by this module:
+% \cs{NewDocumentCommand}, etc.\@, in almost all cases. This allows clean
+% separation of document-level syntax from code-level interfaces. Users have
+% a need to create new document commands, and as such a significant amount of
+% documentation for \pkg{ltcmd} is provided as part of \texttt{usrguide3}. Here,
+% additional material aimed at programmers is provided
+%
+% \StopEventually{}
+%
+% \begin{macrocode}
+%<@@=cmd>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*2ekernel>
+\message{document commands,}
+%</2ekernel>
+% \end{macrocode}
+%
+% \changes{v1.0b}{2021/03/18}{Use \cs{NewModuleRelease}.}
+% \changes{v1.0e}{2021/05/24}{Use \cs{msg_...} instead of \cs{__kernel_msg...}}
+%
+%
+% \pkg{ltcmd} code contains an |^^@| character, which usually has
+% catcode~15, so \cs{IncludeInRelease} will break when this code is
+% being skipped, so we'll save the catcode of |^^@| to restore later:
+% \begin{macrocode}
+%<*2ekernel|latexrelease>
+%<latexrelease>\edef\@latexrelease@catcode@null{\the\catcode`\^^@ }
+%<latexrelease>\catcode`\^^@=12
+\ExplSyntaxOn
+%<latexrelease>\NewModuleRelease{2020/10/01}{ltcmd}
+%<latexrelease> {Document~command~parser}%
+% \end{macrocode}
+%
+% \subsection{Variables and constants}
+%
+% \begin{variable}{\l_@@_arg_spec_tl}
+% Holds the argument specification after normalization of shorthands.
+% \begin{macrocode}
+\tl_new:N \l_@@_arg_spec_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_args_tl}
+% Token list variable for grabbed arguments.
+% \begin{macrocode}
+\tl_new:N \l_@@_args_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_args_i_tl, \l_@@_args_ii_tl}
+% Hold the modified arguments when dealing with default values or
+% processors.
+% \begin{macrocode}
+\tl_new:N \l_@@_args_i_tl
+\tl_new:N \l_@@_args_ii_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_current_arg_int}
+% The number of the current argument being set up: this is used to
+% make sure there are at most 9 arguments, then for creating the
+% expandable auxiliary functions and knowing how many arguments the
+% code function should take.
+% \begin{macrocode}
+\int_new:N \l_@@_current_arg_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_defaults_bool, \l_@@_defaults_tl}
+% The boolean indicates whether there are any argument with default
+% value other than |-NoValue-|; the token list holds the code to
+% determine these default values in terms of other arguments.
+% \begin{macrocode}
+\bool_new:N \l_@@_defaults_bool
+\tl_new:N \l_@@_defaults_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_environment_bool}
+% Generating environments uses the same mechanism as generating functions.
+% However, full processing of arguments is always needed for environments,
+% and so the function-generating code needs to know this.
+% This variable is also used at run time to give correct error messages.
+% \begin{macrocode}
+\bool_new:N \l_@@_environment_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_environment_str}
+% Name of the environment, used at definition time and at run time.
+% \begin{macrocode}
+\str_new:N \l_@@_environment_str
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_expandable_bool}
+% Used to indicate if an expandable command is begin generated, as this
+% affects both the acceptable argument types and how they are implemented.
+% \begin{macrocode}
+\bool_new:N \l_@@_expandable_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_expandable_aux_name_tl}
+% Used to create pretty-printing names for the auxiliaries: although the
+% immediate definition does not vary, the full expansion does and so it
+% does not count as a constant.
+% \begin{macrocode}
+\tl_new:N \l_@@_expandable_aux_name_tl
+\tl_set:Nn \l_@@_expandable_aux_name_tl
+ {
+ \l_@@_function_tl \c_space_tl
+ ( arg~ \int_use:N \l_@@_current_arg_int )
+ }
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_grabber_int}
+% Used (in exceptional cases) to get unique names for grabbers used by
+% expandable commands.
+% \begin{macrocode}
+\int_new:N \g_@@_grabber_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_fn_tl}
+% For passing the pre-formed name of the auxiliary to be used as the
+% parsing function.
+% \begin{macrocode}
+\tl_new:N \l_@@_fn_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_fn_code_tl}
+% For passing the pre-formed name of the auxiliary that contains the
+% actual code.
+% \begin{macrocode}
+\tl_new:N \l_@@_fn_code_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_function_tl}
+% Holds the control sequence name of the function currently being
+% defined: used to avoid passing this as an argument and to avoid repeated
+% use of \cs{cs_to_str:N}.
+% \begin{macrocode}
+\tl_new:N \l_@@_function_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_grab_expandably_bool}
+% When defining a non-expandable command, indicates whether the
+% arguments can all safely be grabbed by expandable grabbers. This is
+% to support abuses of \pkg{xparse} that use protected functions
+% inside csname constructions.
+% \begin{macrocode}
+\bool_new:N \l_@@_grab_expandably_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_obey_spaces_bool}
+% For trailing optionals.
+% \begin{macrocode}
+\bool_new:N \l_@@_obey_spaces_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_last_delimiters_tl}
+% Holds the delimiters (first tokens) of all optional arguments since
+% the previous mandatory argument, to warn about cases where it would
+% be impossible to omit optional arguments completely because the
+% following mandatory argument has the same delimiter as one of the
+% optional arguments.
+% \begin{macrocode}
+\tl_new:N \l_@@_last_delimiters_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_long_bool}
+% Used to indicate that an argument is long, on a per-argument basis.
+% \begin{macrocode}
+\bool_new:N \l_@@_long_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_m_args_int}
+% The number of \texttt{m} arguments: if this is the same as the total
+% number of arguments, then a short-cut can be taken in the creation of
+% the grabber code.
+% \begin{macrocode}
+\int_new:N \l_@@_m_args_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_prefixed_bool}
+% When preparing the signature of non-expandable commands, indicates
+% that the current argument is affected by a processor or by |+|
+% (namely is long).
+% \begin{macrocode}
+\bool_new:N \l_@@_prefixed_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_process_all_tl, \l_@@_process_one_tl, \l_@@_process_some_bool}
+% When preparing the signature, the processors that will be applied to
+% a given argument are collected in \cs{l_@@_process_one_tl}, while
+% \cs{l_@@_process_all_tl} contains processors for all arguments. The
+% boolean indicates whether there are any processors (to bypass the
+% whole endeavour otherwise).
+% \begin{macrocode}
+\tl_new:N \l_@@_process_all_tl
+\tl_new:N \l_@@_process_one_tl
+\bool_new:N \l_@@_process_some_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_saved_args_tl}
+% Stores \cs{l_@@_args_tl} to deal with space-trimming of
+% \texttt{b}-type arguments.
+% \begin{macrocode}
+\tl_new:N \l_@@_saved_args_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_signature_tl}
+% Used when constructing the signature (code for argument grabbing) to
+% hold what will become the implementation of the main function.
+% When arguments are grabbed (at point of use of the command/environment),
+% it also stores the code for grabbing the remaining arguments.
+% \begin{macrocode}
+\tl_new:N \l_@@_signature_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}
+% {\l_@@_some_obey_spaces_bool, \l_@@_some_long_bool, \l_@@_some_short_bool}
+% These flags are set while normalizing the argument specification.
+% The \texttt{obey_spaces} one is used to detect when |!| is used on
+% an argument that is not a trailing optional argument.
+% The other two are used to check whether all short arguments appear
+% before long arguments: this is needed to grab arguments expandably.
+% As soon as the first long argument is seen (other than
+% \texttt{t}-type, whose long status is ignored) the
+% \texttt{some_long} flag is set. The \texttt{some_short} flag is
+% used for expandable commands, to know whether to define a short
+% auxiliary too.
+% \begin{macrocode}
+\bool_new:N \l_@@_some_obey_spaces_bool
+\bool_new:N \l_@@_some_long_bool
+\bool_new:N \l_@@_some_short_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_tmp_prop, \l_@@_tmpa_tl, \l_@@_tmpb_tl}
+% \begin{macro}{\@@_tmp:w}
+% Scratch space.
+% \begin{macrocode}
+\prop_new:N \l_@@_tmp_prop
+\tl_new:N \l_@@_tmpa_tl
+\tl_new:N \l_@@_tmpb_tl
+\cs_new_eq:NN \@@_tmp:w ?
+% \end{macrocode}
+% \end{macro}
+% \end{variable}
+%
+% With \pkg{xparse}, information about commands being (re)defined was
+% switched off by default, unless the |log-declarations| package
+% option was used, so here we'll switch that off as well.
+% \begin{macrocode}
+\msg_redirect_module:nnn { cmd } { info } { none }
+% \end{macrocode}
+%
+% Also add \pkg{cmd} to the \pkg{LaTeX} messages.
+% \begin{macrocode}
+\prop_gput:Nnn \g_msg_module_type_prop { cmd } { LaTeX }
+% \end{macrocode}
+%
+% \subsection{Declaring commands and environments}
+%
+% \begin{macro}{\@@_declare_cmd:Nnn, \@@_declare_expandable_cmd:Nnn}
+% \begin{macro}{\@@_declare_cmd_aux:Nnn}
+% \begin{macro}
+% {\@@_declare_cmd_internal:Nnnn, \@@_declare_cmd_internal:cnxn}
+% The main functions for creating commands set the appropriate flag then
+% use the same internal code to do the definition.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd:Nnn
+ {
+ \bool_set_false:N \l_@@_expandable_bool
+ \@@_declare_cmd_aux:Nnn
+ }
+\cs_new_protected:Npn \@@_declare_expandable_cmd:Nnn
+ {
+ \bool_set_true:N \l_@@_expandable_bool
+ \@@_declare_cmd_aux:Nnn
+ }
+% \end{macrocode}
+% The first stage is to log information, both for the user in the log and
+% for programmatic use in a property list of all declared commands.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_aux:Nnn #1#2#3
+ {
+ \cs_if_exist:NTF #1
+ {
+ \msg_info:nnxx { cmd } { redefine-command }
+ { \token_to_str:N #1 } { \tl_to_str:n {#2} }
+ }
+ {
+ \bool_lazy_or:nnT
+ { \cs_if_exist_p:c { \cs_to_str:N #1 ~ code } }
+ { \cs_if_exist_p:c { \cs_to_str:N #1 ~ defaults } }
+ {
+ \msg_warning:nnx { cmd } { unsupported-let }
+ { \token_to_str:N #1 }
+ }
+ \msg_info:nnxx { cmd } { define-command }
+ { \token_to_str:N #1 } { \tl_to_str:n {#2} }
+ }
+ \bool_set_false:N \l_@@_environment_bool
+ \@@_declare_cmd_internal:Nnnn #1 {#2} {#3} { }
+ }
+% \end{macrocode}
+% At definition time, the variable \cs{l_@@_fn_tl} is only used for error messages.
+% The real business of defining a document command starts with setting up
+% the appropriate name, then normalizing the argument specification to get rid of
+% shorthands.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_internal:Nnnn #1#2#3#4
+ {
+ \tl_set:Nx \l_@@_function_tl { \cs_to_str:N #1 }
+ \tl_set:Nx \l_@@_fn_tl
+ { \exp_not:c { \l_@@_function_tl \c_space_tl } }
+ \@@_normalize_arg_spec:n {#2}
+ \exp_args:No \@@_prepare_signature:n \l_@@_arg_spec_tl
+ \@@_declare_cmd_code:Nnn #1 {#2} {#3}
+ #4
+ \@@_break_point:n {#2}
+ }
+\cs_generate_variant:Nn \@@_declare_cmd_internal:Nnnn { cnx }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_break_point:n}
+% A marker used to escape from creating a definition if necessary.
+% \begin{macrocode}
+\cs_new_eq:NN \@@_break_point:n \use_none:n
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_declare_cmd_code:Nnn}
+% \begin{macro}
+% {\@@_declare_cmd_code_aux:Nnn, \@@_declare_cmd_code_expandable:Nnn}
+% The appropriate auxiliary is called.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_code:Nnn
+ {
+ \bool_if:NTF \l_@@_grab_expandably_bool
+ { \@@_declare_cmd_code_expandable:Nnn }
+ { \@@_declare_cmd_code_aux:Nnn }
+ }
+% \end{macrocode}
+% Standard functions call \cs{@@_start:nNNnnn}, which receives the
+% argument specification, an auxiliary used for
+% grabbing arguments, an auxiliary containing the code, and then the
+% signature, default arguments, and processors.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_code_aux:Nnn #1#2#3
+ {
+ \cs_generate_from_arg_count:cNnn
+ { \l_@@_function_tl \c_space_tl code }
+ \cs_set_protected:Npn \l_@@_current_arg_int {#3}
+ \cs_set_protected_nopar:Npx #1
+ {
+ \bool_if:NTF \l_@@_environment_bool
+ {
+ \@@_start_env:nnnnn { \exp_not:n {#2} }
+ { \l_@@_environment_str }
+ }
+ {
+ \@@_start:nNNnnn { \exp_not:n {#2} }
+ \exp_not:c { \l_@@_function_tl \c_space_tl }
+ \exp_not:c { \l_@@_function_tl \c_space_tl code }
+ }
+ { \exp_not:o \l_@@_signature_tl }
+ {
+ \bool_if:NT \l_@@_defaults_bool
+ { \exp_not:o \l_@@_defaults_tl }
+ }
+ {
+ \bool_if:NT \l_@@_process_some_bool
+ { \exp_not:o \l_@@_process_all_tl }
+ }
+ }
+ }
+% \end{macrocode}
+% Expandable functions and functions whose arguments can be grabbed
+% expandably call \cs{@@_start_expandable:nNNNNn}, which receives the
+% argument specification, four auxiliaries (two for grabbing arguments, one for
+% the code, and one for default arguments), and finally the signature.
+% Non-expandable functions that take this branch should nevertheless
+% be protected, as well as their \texttt{code} function. They will
+% only be expanded in contexts such as constructing a csname.
+% The two grabbers (named after the function with one or two spaces)
+% are needed when there are both short and long arguments; otherwise
+% the same grabber is included twice in the definition. If all
+% arguments are long or all are short the (only) grabber is defined
+% correspondingly to be long/short. Otherwise two grabbers are
+% defined, one long, one short.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_code_expandable:Nnn #1#2#3
+ {
+ \exp_args:Ncc \cs_generate_from_arg_count:NNnn
+ { \l_@@_function_tl \c_space_tl code }
+ { cs_set \bool_if:NF \l_@@_expandable_bool { _protected } :Npn }
+ \l_@@_current_arg_int {#3}
+ \bool_if:NT \l_@@_defaults_bool
+ {
+ \use:x
+ {
+ \cs_generate_from_arg_count:cNnn
+ { \l_@@_function_tl \c_space_tl defaults }
+ \cs_set:Npn \l_@@_current_arg_int
+ { \exp_not:o \l_@@_defaults_tl }
+ }
+ }
+ \bool_if:NTF \l_@@_expandable_bool
+ { \cs_set_nopar:Npx } { \cs_set_protected_nopar:Npx } #1
+ {
+ \exp_not:N \@@_start_expandable:nNNNNn
+ { \exp_not:n {#2} }
+ \exp_not:c { \l_@@_function_tl \c_space_tl }
+ \exp_not:c
+ {
+ \l_@@_function_tl \c_space_tl
+ \bool_if:NT \l_@@_some_short_bool
+ { \bool_if:NT \l_@@_some_long_bool { \c_space_tl } }
+ }
+ \exp_not:c { \l_@@_function_tl \c_space_tl code }
+ \bool_if:NTF \l_@@_defaults_bool
+ { \exp_not:c { \l_@@_function_tl \c_space_tl defaults } }
+ { ? }
+ { \exp_not:o \l_@@_signature_tl }
+ }
+ \bool_if:NTF \l_@@_some_long_bool
+ {
+ \bool_if:NT \l_@@_some_short_bool
+ {
+ \cs_set_nopar:cpx { \l_@@_function_tl \c_space_tl \c_space_tl }
+ ##1##2 { ##1 {##2} }
+ }
+ \cs_set:cpx
+ }
+ { \cs_set_nopar:cpx }
+ { \l_@@_function_tl \c_space_tl } ##1##2 { ##1 {##2} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_declare_env:nnnn}
+% \begin{macro}{\@@_declare_env_internal:nnnn}
+% The lead-off to creating an environment is much the same as that for
+% creating a command: issue the appropriate message, store the argument
+% specification then hand off to an internal function.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_env:nnnn #1#2
+ {
+ \str_set:Nx \l_@@_environment_str {#1}
+ \str_set:Nx \l_@@_environment_str
+ { \tl_trim_spaces:o { \l_@@_environment_str } }
+ \cs_if_exist:cTF { \l_@@_environment_str }
+ {
+ \msg_info:nnxx { cmd } { redefine-environment }
+ { \l_@@_environment_str } { \tl_to_str:n {#2} }
+ }
+ {
+ \msg_info:nnxx { cmd } { define-environment }
+ { \l_@@_environment_str } { \tl_to_str:n {#2} }
+ }
+ \bool_set_false:N \l_@@_expandable_bool
+ \bool_set_true:N \l_@@_environment_bool
+ \exp_args:NV \@@_declare_env_internal:nnnn
+ \l_@@_environment_str {#2}
+ }
+% \end{macrocode}
+% Creating a document environment requires a few more steps than creating
+% a single command. In order to pass the arguments of the command to the
+% end of the function, it is necessary to store the grabbed arguments.
+% To do that, the function used at the end of the environment has to be
+% redefined to contain the appropriate information. To minimize the amount
+% of expansion at point of use, the code here is expanded now as well as
+% when used.
+% The last argument of \cs{@@_declare_cmd_internal:Nnnn} is only run
+% if the definition succeeded. In package mode this ensures that the
+% original definition of the environment is not changed if the
+% definition fails for any reason. This also avoids an error when
+% defining the \verb*|end aux | function when the user asks for more
+% than $9$ arguments.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_env_internal:nnnn #1#2#3#4
+ {
+ \@@_declare_cmd_internal:cnxn { environment~ #1 } {#2}
+ {
+ \cs_set_nopar:Npx \exp_not:c { environment~ #1 ~end~aux }
+ {
+ \exp_not:N \exp_not:N \exp_not:c { environment~ #1~end~aux~ }
+ \exp_not:n { \exp_not:o \l_@@_args_tl }
+ }
+ \exp_not:n {#3}
+ }
+ {
+ \cs_set_nopar:cpx { environment~ #1 ~end }
+ { \exp_not:c { environment~ #1 ~end~aux } }
+ \cs_generate_from_arg_count:cNnn
+ { environment~ #1 ~end~aux~ } \cs_set:Npn
+ \l_@@_current_arg_int {#4}
+ \cs_set_eq:cc {#1} { environment~ #1 }
+ \cs_set_eq:cc { end #1 } { environment~ #1 ~end }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Structure of \pkg{xparse} commands}
+%
+% \begin{macro}{\@@_start_env:nnnnn, \@@_start:nNNnnn}
+% For error messages that occur during run-time when getting arguments
+% of environments it is necessary to keep track of the environment
+% name. We begin non-expandable commands with a token equal to
+% \cs{scan_stop:}, whose name gives a reasonable error message if the
+% command is used inside a csname and protects against
+% \texttt{f}-expansion. This is useless for environments since
+% \cs{begin} is already not expandable. Both the command and
+% environment codes start with \cs{group_align_safe_begin:}, then
+% \cs{@@_run_code:} (used by both) does \cs{group_align_safe_end:}, so
+% that delimited arguments may be grabbed in alignments if they
+% contain and alignment tab token (see latex3/latex3/issues/839).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_start_env:nnnnn #1#2
+ {
+ \conditionally@traceoff
+ \group_align_safe_begin:
+ \str_set:Nn \l_@@_environment_str {#2}
+ \bool_set_true:N \l_@@_environment_bool
+ \@@_start_aux:ccnnnn
+ { environment~ \l_@@_environment_str \c_space_tl }
+ { environment~ \l_@@_environment_str \c_space_tl code }
+ {#1}
+ }
+\cs_new_protected:Npx \@@_start:nNNnnn #1#2#3
+ {
+ \exp_not:c { xparse~function~is~not~expandable }
+ \exp_not:N \conditionally@traceoff
+ \exp_not:N \group_align_safe_begin:
+ \exp_not:n { \bool_set_false:N \l_@@_environment_bool }
+ \exp_not:N \@@_start_aux:NNnnnn
+ #2 #3 {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_start_aux:NNnnnn, \@@_start_aux:ccnnnn}
+% This sets up a few variables to minimize the boilerplate code
+% included in all \pkg{xparse}-defined commands. It then runs the
+% grabbers~|#4|. Again, the argument specification |#1| is only for
+% diagnostics.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_start_aux:NNnnnn #1#2#3#4#5#6
+ {
+ \tl_clear:N \l_@@_args_tl
+ \tl_set:Nn \l_@@_fn_tl {#1}
+ \tl_set:Nn \l_@@_fn_code_tl {#2}
+ \tl_set:Nn \l_@@_defaults_tl {#5}
+ \tl_set:Nn \l_@@_process_all_tl {#6}
+ #4 \@@_run_code:
+ }
+\cs_generate_variant:Nn \@@_start_aux:NNnnnn { cc }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_run_code:}
+% After arguments are grabbed, this function is responsible for
+% inserting default values, running processors, and finally doing
+% \cs{group_align_safe_end:} as promised, and running the code.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_run_code:
+ {
+ \tl_if_empty:NF \l_@@_defaults_tl { \@@_defaults: }
+ \tl_if_empty:NF \l_@@_process_all_tl { \@@_args_process: }
+ \group_align_safe_end:
+ \conditionally@traceon
+ \exp_after:wN \l_@@_fn_code_tl \l_@@_args_tl
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_defaults:}
+% \begin{macro}{\@@_defaults_def:, \@@_defaults_def:nn, \@@_defaults_def:nnn}
+% \begin{macro}{\@@_defaults_aux:, \@@_defaults_error:w}
+% First construct \cs{@@_tmp:w} (see below) that will receive
+% the arguments found so far and determine default values for any
+% missing argument. Then call it repeatedly until the set of
+% arguments stabilizes. Since that could lead to an infinite loop we
+% only call it up to nine times, the maximal number needed for
+% stabilization if there is a chain of arguments that depend on each
+% other. If that fails to stabilize raise an error.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_defaults:
+ {
+ \@@_defaults_def:
+ \tl_set_eq:NN \l_@@_args_i_tl \l_@@_args_tl
+ \@@_defaults_aux: \@@_defaults_aux: \@@_defaults_aux:
+ \@@_defaults_aux: \@@_defaults_aux: \@@_defaults_aux:
+ \@@_defaults_aux: \@@_defaults_aux: \@@_defaults_aux:
+ \@@_defaults_error:w
+ \q_recursion_stop
+ \tl_set_eq:NN \l_@@_args_tl \l_@@_args_i_tl
+ }
+\cs_new_protected:Npn \@@_defaults_aux:
+ {
+ \tl_set:Nx \l_@@_args_ii_tl
+ { \exp_after:wN \@@_tmp:w \l_@@_args_i_tl }
+ \tl_if_eq:NNT \l_@@_args_ii_tl \l_@@_args_i_tl
+ { \use_none_delimit_by_q_recursion_stop:w }
+ \tl_set_eq:NN \l_@@_args_i_tl \l_@@_args_ii_tl
+ }
+\cs_new_protected:Npn \@@_defaults_error:w \q_recursion_stop
+ {
+ \msg_error:nnx { cmd } { loop-in-defaults }
+ { \@@_environment_or_command: }
+ }
+% \end{macrocode}
+% To construct \cs{@@_tmp:w}, first go through the arguments
+% found and the corresponding defaults, building a token list with
+% |{#|\meta{arg number}|}| for arguments found in the input (whose
+% default will not be used) and otherwise
+% |{|\cs{exp_not:n}\Arg{default}|}| for arguments whose default will
+% be used.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_defaults_def:
+ {
+ \tl_clear:N \l_@@_tmpa_tl
+ \int_zero:N \l_@@_current_arg_int
+ \@@_tl_mapthread_function:NNN \l_@@_args_tl \l_@@_defaults_tl
+ \@@_defaults_def:nn
+ \cs_generate_from_arg_count:NNVo \@@_tmp:w \cs_set:Npn
+ \l_@@_current_arg_int \l_@@_tmpa_tl
+ }
+\cs_generate_variant:Nn \cs_generate_from_arg_count:NNnn { NNVo }
+\cs_new_protected:Npn \@@_defaults_def:nn
+ {
+ \int_incr:N \l_@@_current_arg_int
+ \exp_args:NV \@@_defaults_def:nnn \l_@@_current_arg_int
+ }
+\cs_new_protected:Npn \@@_defaults_def:nnn #1#2#3
+ {
+ \tl_put_right:Nx \l_@@_tmpa_tl
+ {
+ {
+ \exp_not:N \exp_not:n
+ {
+ \tl_if_novalue:nTF {#2}
+ { \exp_not:o {#3} }
+ { \exp_not:n { ## #1 } }
+ }
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_args_process:}
+% \begin{macro}{\@@_args_process_loop:nn, \@@_args_process_aux:n}
+% Loop through arguments (stored in \cs{l_@@_args_tl}) and the
+% corresponding processors (in \cs{l_@@_process_all_tl})
+% simultaneously, apply all processors for each argument and store the
+% result back into \cs{l_@@_args_tl}. To allow processors to depend
+% on other arguments, for every processor define a temporary auxiliary
+% that receives all arguments \cs{l_@@_args_tl}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_args_process:
+ {
+ \tl_clear:N \l_@@_args_ii_tl
+ \@@_tl_mapthread_function:NNN
+ \l_@@_args_tl
+ \l_@@_process_all_tl
+ \@@_args_process_loop:nn
+ \tl_set_eq:NN \l_@@_args_tl \l_@@_args_ii_tl
+ }
+\cs_new_protected:Npn \@@_args_process_loop:nn #1#2
+ {
+ \tl_set:Nn \ProcessedArgument {#1}
+ \tl_if_novalue:nF {#1}
+ { \tl_map_function:nN {#2} \@@_args_process_aux:n }
+ \tl_put_right:No \l_@@_args_ii_tl
+ { \exp_after:wN { \ProcessedArgument } }
+ }
+\cs_new_protected:Npn \@@_args_process_aux:n #1
+ {
+ \cs_generate_from_arg_count:NNnn \@@_tmp:w \cs_set:Npn
+ { \tl_count:N \l_@@_args_tl } {#1}
+ \exp_args:NNNo \exp_after:wN \@@_tmp:w \l_@@_args_tl
+ { \ProcessedArgument }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_start_expandable:nNNNNn}
+% This is called for all expandable commands. |#6| is the signature,
+% responsible for grabbing arguments. |#5| is used to determine
+% default values (or is |?| if there are none). |#4| is the code to run.
+% |#2|~and~|#3| are functions (named after the command) that grab a single
+% argument in the input stream (|#3|~is~short). The argument specification |#1| is
+% only used by diagnostic functions. Same as for the non-expandable
+% version, this starts with \cs{group_align_safe_begin:}, which
+% expands to nothing, so may be safely used in an expandable context.
+% \begin{macrocode}
+\cs_new:Npn \@@_start_expandable:nNNNNn #1#2#3#4#5#6
+ {
+ \group_align_safe_begin:
+ #6 \@@_end_expandable:NNw #5 #4 \q_@@ #2#3
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_end_expandable:NNw}
+% \begin{macro}[EXP]{\@@_end_expandable_aux:w}
+% \begin{macro}[EXP]{\@@_end_expandable_aux:nNNNN}
+% \begin{macro}[EXP]{\@@_end_expandable_defaults:nnnNNn}
+% \begin{macro}[EXP]{\@@_end_expandable_defaults:nnw}
+% \begin{macro}[EXP]{\@@_end_expandable_defaults:nw}
+% Followed by a function |#1| to determine default values (or |?| if
+% there are no defaults), the code
+% |#2|, arguments that have been grabbed, then \cs{q_@@} and two generic
+% grabbers. The idea to find default values is similar to the
+% non-expandable case but we cannot define an auxiliary function, so
+% at every step in the loop we need to go through all arguments
+% searching for which ones started out as |-NoValue-| and replacing
+% these by the newly computed values. In fact we need to keep track
+% of three versions of all arguments: the original version, the
+% previous version with default values, and the currently built
+% version (first argument of \cs{@@_end_expandable_defaults:nnnNNn}).
+% \begin{macrocode}
+\cs_new:Npn \@@_end_expandable:NNw #1#2
+ { \@@_end_expandable_aux:w #1#2 \prg_do_nothing: }
+\cs_new:Npn \@@_end_expandable_aux:w #1#2#3 \q_@@
+ { \exp_args:No \@@_end_expandable_aux:nNNNN {#3} #1 #2 }
+\cs_new:Npn \@@_end_expandable_aux:nNNNN #1#2#3#4#5
+ {
+ \token_if_eq_charcode:NNT ? #2 { \exp_after:wN \use_iv:nnnn }
+ \@@_end_expandable_defaults:nnnNNn {#1} { } {#1} #2#3
+ { } { } { } { } { } { } { } { } { } { }
+ {
+ \msg_expandable_error:nnf { cmd } { loop-in-defaults }
+ { \exp_args:Nf \tl_trim_spaces:n { \token_to_str:N #4 } }
+ \use_iv:nnnn
+ }
+ \q_stop
+ }
+\cs_new:Npn \@@_end_expandable_defaults:nnnNNn #1#2#3#4#5#6
+ {
+ #6
+ \str_if_eq:nnTF {#1} {#2}
+ { \use_i_delimit_by_q_stop:nw { \group_align_safe_end: #5 #1 } }
+ {
+ \exp_args:No \@@_tl_mapthread_function:nnN
+ { #4 #1 } {#3}
+ \@@_end_expandable_defaults:nnw
+ \@@_end_expandable_defaults:nnnNNn { } {#1} {#3} #4 #5
+ }
+ }
+\cs_new:Npn \@@_end_expandable_defaults:nnw #1#2
+ {
+ \tl_if_novalue:nTF {#2}
+ { \exp_args:No \@@_end_expandable_defaults:nw {#1} }
+ { \@@_end_expandable_defaults:nw {#2} }
+ }
+\cs_new:Npn \@@_end_expandable_defaults:nw
+ #1#2 \@@_end_expandable_defaults:nnnNNn #3
+ { #2 \@@_end_expandable_defaults:nnnNNn { #3 {#1} } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Normalizing the argument specifications}
+%
+% The goal here is to expand aliases and check that the argument
+% specification is valid before the main parsing run. If it is not
+% valid the entire set up is abandoned to avoid any strange internal
+% errors. A function is provided for each argument type that will grab
+% any extra data items and call the loop function after performing the
+% following checks and tasks.
+% \begin{itemize}
+% \item Check that each argument has the correct number of data items
+% associated with it, and that where a single character is required,
+% one has actually been supplied.
+% \item Check that processors and the markers~|+| and~|!| are followed
+% by an argument for which they make sense, and are not redundant.
+% \item Check the absence of forbidden types for expandable commands,
+% namely \texttt{G}/\texttt{v} always, and \texttt{l}/\texttt{u}
+% after optional arguments (\pkg{xparse} may have inserted braces
+% due to a failed search for an optional argument).
+% \item Check that no optional argument is followed by a mandatory
+% argument with the same delimiter, as otherwise the optional
+% argument could never be omitted.
+% \item Keep track in \cs{l_@@_some_long_bool} and
+% \cs{l_@@_some_short_bool} of whether the command has some
+% long/short arguments.
+% \item Keep track in \cs{l_@@_grab_expandably_bool} of whether all
+% arguments are \texttt{m}/\texttt{l}/\texttt{u} type and short
+% arguments appear before long ones, in which case they can be
+% grabbed expandably just as safely as they could be grabbed
+% nonexpandably. Regardless of that, arguments of expandable
+% commands will be grabbed expandably and arguments of environments
+% will not (because the list of arguments built by non-expandable
+% grabbing is used to pass them to the end-environment code).
+% \end{itemize}
+% Further checks happen at the end of the loop:
+% \begin{itemize}
+% \item that there are at most $9$ arguments;
+% \item that an expandable command does not end with an optional
+% argument (this case is detected by using the fact that
+% \cs{l_@@_last_delimiters_tl} is cleared by every mandatory argument
+% and filled by every optional argument).
+% \end{itemize}
+%
+% \begin{macro}{\@@_normalize_arg_spec:n}
+% \begin{macro}{\@@_normalize_arg_spec_loop:n}
+% Loop through the argument specification, calling an auxiliary
+% specific to each argument type. If any argument is unknown stop the
+% definition.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_arg_spec:n #1
+ {
+ \int_zero:N \l_@@_current_arg_int
+ \tl_clear:N \l_@@_last_delimiters_tl
+ \tl_clear:N \l_@@_arg_spec_tl
+ \bool_set_true:N \l_@@_grab_expandably_bool
+ \bool_set_false:N \l_@@_obey_spaces_bool
+ \bool_set_false:N \l_@@_long_bool
+ \bool_set_false:N \l_@@_some_obey_spaces_bool
+ \bool_set_false:N \l_@@_some_long_bool
+ \bool_set_false:N \l_@@_some_short_bool
+ \@@_normalize_arg_spec_loop:n #1
+ \q_recursion_tail \q_recursion_tail \q_recursion_tail \q_recursion_stop
+ \int_compare:nNnT \l_@@_current_arg_int > 9
+ {
+ \msg_error:nnxx { cmd } { too-many-arguments }
+ { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+ \bool_if:NT \l_@@_expandable_bool
+ {
+ \tl_if_empty:NF \l_@@_last_delimiters_tl
+ {
+ \msg_error:nnxx { cmd } { expandable-ending-optional }
+ { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+ }
+ \bool_if:NT \l_@@_expandable_bool
+ { \bool_set_true:N \l_@@_grab_expandably_bool }
+ \bool_if:NT \l_@@_environment_bool
+ { \bool_set_false:N \l_@@_grab_expandably_bool }
+ }
+\cs_new_protected:Npn \@@_normalize_arg_spec_loop:n #1
+ {
+ \quark_if_recursion_tail_stop:n {#1}
+ \int_incr:N \l_@@_current_arg_int
+ \cs_if_exist_use:cF { @@_normalize_type_ \tl_to_str:n {#1} :w }
+ {
+ \bool_lazy_any:nTF
+ {
+ { \str_if_eq_p:nn {#1} { G } }
+ { \str_if_eq_p:nn {#1} { g } }
+ { \str_if_eq_p:nn {#1} { l } }
+ { \str_if_eq_p:nn {#1} { u } }
+ }
+ {
+ \msg_error:nnxx { cmd } { xparse-argument-type }
+ { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+ }
+ {
+ \msg_error:nnxx { cmd } { unknown-argument-type }
+ { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+ }
+ \@@_bad_def:wn
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_normalize_type_d:w,
+% \@@_normalize_type_e:w,
+% \@@_normalize_type_o:w,
+% \@@_normalize_type_O:w,
+% \@@_normalize_type_r:w,
+% \@@_normalize_type_s:w,
+% }
+% These argument types are aliases of more general ones, for example
+% with the default argument |-NoValue-|. To easily insert that marker
+% expanded in the definitions we call \cs{@@_tmp:w} with the argument
+% |-NoValue-|. For argument types that need additional data, check
+% that the data is present (not \cs{q_recursion_tail}) before
+% proceeding.
+% \begin{macrocode}
+\cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new_protected:Npn \@@_normalize_type_d:w ##1##2
+ {
+ \quark_if_recursion_tail_stop_do:nn {##2} { \@@_bad_arg_spec:wn }
+ \@@_normalize_type_D:w {##1} {##2} {#1}
+ }
+ \cs_new_protected:Npn \@@_normalize_type_e:w ##1
+ {
+ \quark_if_recursion_tail_stop_do:nn {##1} { \@@_bad_arg_spec:wn }
+ \@@_normalize_type_E:w {##1} { }
+ }
+ \cs_new_protected:Npn \@@_normalize_type_o:w
+ { \@@_normalize_type_D:w [ ] {#1} }
+ \cs_new_protected:Npn \@@_normalize_type_O:w
+ { \@@_normalize_type_D:w [ ] }
+ \cs_new_protected:Npn \@@_normalize_type_r:w ##1##2
+ {
+ \quark_if_recursion_tail_stop_do:nn {##2} { \@@_bad_arg_spec:wn }
+ \@@_normalize_type_R:w {##1} {##2} {#1}
+ }
+ \cs_new_protected:Npn \@@_normalize_type_s:w
+ { \@@_normalize_type_t:w * }
+ }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_normalize_type_>:w,
+% \@@_normalize_type_+:w,
+% \@@_normalize_type_!:w,
+% }
+% Check that these prefixes have arguments, namely that the next token
+% is not \cs{q_recursion_tail}, and remember to leave it after the
+% looping macro. Processors are forbidden in expandable commands.
+% If all is good, store the prefix in the cleaned up
+% \cs{l_@@_arg_spec_tl}, and decrement the argument number as prefixes
+% do not correspond to arguments.
+% \begin{macrocode}
+\cs_new_protected:cpn { @@_normalize_type_>:w } #1#2
+ {
+ \quark_if_recursion_tail_stop_do:nn {#2} { \@@_bad_arg_spec:wn }
+ \bool_if:NT \l_@@_expandable_bool
+ {
+ \msg_error:nnxx { cmd } { processor-in-expandable }
+ { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+ \tl_put_right:Nx \l_@@_arg_spec_tl { > { \tl_trim_spaces:n {#1} } }
+ \int_decr:N \l_@@_current_arg_int
+ \bool_set_false:N \l_@@_grab_expandably_bool
+ \@@_normalize_arg_spec_loop:n {#2}
+ }
+\cs_new_protected:cpn { @@_normalize_type_+:w } #1
+ {
+ \quark_if_recursion_tail_stop_do:nn {#1} { \@@_bad_arg_spec:wn }
+ \bool_if:NT \l_@@_long_bool
+ {
+ \msg_error:nnxx { cmd } { two-markers }
+ { \@@_environment_or_command: } { + }
+ \@@_bad_def:wn
+ }
+ \bool_set_true:N \l_@@_long_bool
+ \int_decr:N \l_@@_current_arg_int
+ \@@_normalize_arg_spec_loop:n {#1}
+ }
+\cs_new_protected:cpn { @@_normalize_type_!:w } #1
+ {
+ \quark_if_recursion_tail_stop_do:nn {#1} { \@@_bad_arg_spec:wn }
+ \bool_if:NT \l_@@_obey_spaces_bool
+ {
+ \msg_error:nnxx { cmd } { two-markers }
+ { \@@_environment_or_command: } { ! }
+ \@@_bad_def:wn
+ }
+ \bool_set_true:N \l_@@_obey_spaces_bool
+ \bool_set_true:N \l_@@_some_obey_spaces_bool
+ \int_decr:N \l_@@_current_arg_int
+ \@@_normalize_arg_spec_loop:n {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_normalize_type_D:w,
+% \@@_normalize_type_E:w,
+% \@@_normalize_type_t:w,
+% }
+% \begin{macro}{\@@_normalize_E_unique_check:w}
+% Optional argument types. Check that all required data is present
+% (and consists of single characters if applicable) and check for
+% forbidden types for expandable commands. For \texttt{E}-type
+% require that there is at least one embellishment, that each one is a
+% single character, and that there aren't more optional arguments than
+% embellishments; also remember that each embellishment counts as one
+% argument for \cs{l_@@_current_arg_int}. Then in each case
+% store the data in \cs{l_@@_arg_spec_tl}, and
+% for later checks store in \cs{l_@@_last_delimiters_tl} the tokens
+% whose presence determines whether there is an optional argument (for
+% braces store |{}|, seen later as an empty delimiter).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_type_D:w #1#2#3
+ {
+ \quark_if_recursion_tail_stop_do:nn {#3} { \@@_bad_arg_spec:wn }
+ \@@_single_token_check:n {#1} \@@_allowed_token_check:N #1
+ \@@_single_token_check:n {#2}
+ \@@_add_arg_spec:n { D #1 #2 {#3} }
+ \tl_put_right:Nn \l_@@_last_delimiters_tl {#1}
+ \bool_set_false:N \l_@@_grab_expandably_bool
+ \@@_normalize_arg_spec_loop:n
+ }
+\cs_new_protected:Npn \@@_normalize_type_E:w #1#2
+ {
+ \quark_if_recursion_tail_stop_do:nn {#2} { \@@_bad_arg_spec:wn }
+ \tl_if_blank:nT {#1} { \@@_bad_arg_spec:wn }
+ \tl_map_function:nN {#1} \@@_single_token_check:n
+ \tl_map_function:nN {#1} \@@_allowed_token_check:N
+ \@@_normalize_E_unique_check:w #1 \q_nil \q_stop
+ \int_compare:nNnT { \tl_count:n {#2} } > { \tl_count:n {#1} }
+ { \@@_bad_arg_spec:wn }
+ \@@_add_arg_spec:n { E {#1} {#2} }
+ \tl_put_right:Nn \l_@@_last_delimiters_tl {#1}
+ \bool_set_false:N \l_@@_grab_expandably_bool
+ \int_add:Nn \l_@@_current_arg_int { \tl_count:n {#1} - 1 }
+ \@@_normalize_arg_spec_loop:n
+ }
+\cs_new_protected:Npn \@@_normalize_E_unique_check:w #1#2 \q_stop
+ {
+ \quark_if_nil:NF #1
+ {
+ \tl_if_in:nnT {#2} {#1} { \@@_bad_arg_spec:wn }
+ \@@_normalize_E_unique_check:w #2 \q_stop
+ }
+ }
+\cs_new_protected:Npn \@@_normalize_type_t:w #1
+ {
+ \quark_if_recursion_tail_stop_do:Nn #1 { \@@_bad_arg_spec:wn }
+ \@@_single_token_check:n {#1} \@@_allowed_token_check:N #1
+ \tl_put_right:Nx \l_@@_arg_spec_tl
+ {
+ \bool_if:NT \l_@@_obey_spaces_bool { ! }
+ t \exp_not:n {#1}
+ }
+ \tl_put_right:Nn \l_@@_last_delimiters_tl {#1}
+ \bool_set_false:N \l_@@_grab_expandably_bool
+ \bool_set_false:N \l_@@_obey_spaces_bool
+ \bool_set_false:N \l_@@_long_bool
+ \@@_normalize_arg_spec_loop:n
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_normalize_type_m:w,
+% \@@_normalize_type_R:w,
+% \@@_normalize_type_v:w
+% }
+% Mandatory arguments. First check the required data is present,
+% consists of single characters where applicable, and that the argument
+% type is allowed for expandable commands if applicable. For the
+% \texttt{m} and \texttt{R} argument types check that they do not
+% follow some optional argument with that delimiter as otherwise the
+% optional argument could not be omitted. Then save data in
+% \cs{l_@@_arg_spec_tl}, count the mandatory argument, and empty the
+% list of last delimiters.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_type_m:w
+ {
+ \@@_delimiter_check:nnn { } { m } { \iow_char:N \{ }
+ \@@_add_arg_spec_mandatory:n { m }
+ \@@_normalize_arg_spec_loop:n
+ }
+\cs_new_protected:Npn \@@_normalize_type_R:w #1#2#3
+ {
+ \quark_if_recursion_tail_stop_do:nn {#3} { \@@_bad_arg_spec:wn }
+ \@@_single_token_check:n {#1} \@@_allowed_token_check:N #1
+ \@@_single_token_check:n {#2}
+ \@@_delimiter_check:nnn {#1} { R/r } { \tl_to_str:n {#1} }
+ \bool_set_false:N \l_@@_grab_expandably_bool
+ \@@_add_arg_spec_mandatory:n { R #1 #2 {#3} }
+ \@@_normalize_arg_spec_loop:n
+ }
+\cs_new_protected:Npn \@@_normalize_type_v:w
+ {
+ \@@_normalize_check_gv:N v
+ \@@_add_arg_spec_mandatory:n { v }
+ \@@_normalize_arg_spec_loop:n
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_normalize_type_b:w}
+% This argument type is not allowed for commands. This is only
+% allowed at the end of the argument specification, hence we check
+% that |#1| is the end.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_type_b:w #1
+ {
+ \bool_if:NF \l_@@_environment_bool
+ {
+ \msg_error:nnxx { cmd } { invalid-command-arg }
+ { \@@_environment_or_command: } { b }
+ \@@_bad_def:wn
+ }
+ \tl_clear:N \l_@@_last_delimiters_tl
+ \@@_add_arg_spec:n { b }
+ \quark_if_recursion_tail_stop:n {#1}
+ \msg_error:nnxx { cmd } { arg-after-body }
+ { \@@_environment_or_command: }
+ { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_single_token_check:n}
+% Checks that the argument is a single (non-space) token (possibly
+% surrounded by spaces), and aborts the definition otherwise.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_single_token_check:n #1
+ {
+ \tl_trim_spaces_apply:nN {#1} \tl_if_single_token:nF
+ {
+ \msg_error:nnxx { cmd } { not-single-token }
+ { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_allowed_token_check:N}
+% Some tokens are now allowed as delimiters for some argument types,
+% notably implicit begin/end-group tokens (|\bgroup|/|\egroup|).
+% The major problem with these tokens is that for |\peek_...| functions,
+% a literal~|{|$_1$. is virtually indistinguishable from a |\bgroup| or
+% other token which was |\let| to a~|{|$_1$, and the same goes
+% for~|}|$_2$. All other tokens can be easily distingushed from their
+% implicit counterparts by grabbing them and looking at the string
+% length (see \cs{@@_token_if_cs:NTF}), but for begin/end group tokens
+% that is not possible without the risk of mistakenly grabbing the
+% entire brace group (potentially leading to a~\texttt{!~Runaway argument}
+% error) or trying to grab a |}|$_2$, leading to
+% an~\verb|! Argument of \dots has an extra }| error.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_allowed_token_check:N #1
+ {
+ \token_if_eq_meaning:NNTF #1 \c_group_begin_token
+ { \use:n }
+ {
+ \token_if_eq_meaning:NNTF #1 \c_group_end_token
+ { \use:n }
+ { \use_none:n }
+ }
+ {
+ \msg_error:nnxxx { cmd } { forbidden-implicit-group-token }
+ { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+ {
+ \token_if_eq_meaning:NNTF #1 \c_group_begin_token
+ { begin } { end }
+ }
+ \@@_bad_def:wn
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_normalize_check_gv:N, \@@_normalize_check_lu:N}
+% Called for arguments that are always forbidden, or forbidden after
+% an optional argument, for expandable commands.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_check_gv:N #1
+ {
+ \bool_if:NT \l_@@_expandable_bool
+ {
+ \msg_error:nnxx { cmd } { invalid-expandable-argument-type }
+ { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+ \bool_set_false:N \l_@@_grab_expandably_bool
+ }
+\cs_new_protected:Npn \@@_normalize_check_lu:N #1
+ {
+ \bool_if:NT \l_@@_expandable_bool
+ {
+ \tl_if_empty:NF \l_@@_last_delimiters_tl
+ {
+ \msg_error:nnxx { cmd } { invalid-after-optional-expandably }
+ { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_delimiter_check:nnn}
+% Called for \texttt{m} and \texttt{R} arguments. Checks that the
+% leading token does not coincide with the token denoting the presence
+% of a previous optional argument. Instead of dealing with braces for
+% the \texttt{m}-type we use an empty delimiter to denote that case.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_delimiter_check:nnn #1#2#3
+ {
+ \tl_map_inline:Nn \l_@@_last_delimiters_tl
+ {
+ \tl_if_eq:nnT {##1} {#1}
+ {
+ \msg_warning:nnxx { cmd } { optional-mandatory }
+ {#2} {#3}
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_bad_arg_spec:wn, \@@_bad_def:wn}
+% If the argument specification is wrong, this provides an escape from
+% the entire definition process.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_bad_arg_spec:wn #1 \@@_break_point:n #2
+ {
+ \msg_error:nnxx { cmd } { bad-arg-spec }
+ { \@@_environment_or_command: } { \tl_to_str:n {#2} }
+ }
+\cs_new_protected:Npn \@@_bad_def:wn #1 \@@_break_point:n #2 { }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_arg_spec:n, \@@_add_arg_spec_mandatory:n}
+% When adding an argument to the argument specification, set the
+% \texttt{some_long} or \texttt{some_short} booleans as appropriate
+% and clear the booleans keeping track of |+| and |!| markers.
+% Before that, test for a short argument following some long
+% arguments: this is forbidden for expandable commands and prevents
+% grabbing arguments expandably.
+%
+% For mandatory arguments do some more work, in particular complain if
+% they were preceeded by~|!|.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_arg_spec:n #1
+ {
+ \bool_lazy_and:nnT
+ { ! \l_@@_long_bool }
+ { \l_@@_some_long_bool }
+ {
+ \bool_if:NT \l_@@_expandable_bool
+ {
+ \msg_error:nnx { cmd } { inconsistent-long }
+ { \iow_char:N \\ \l_@@_function_tl }
+ \@@_bad_def:wn
+ }
+ \bool_set_false:N \l_@@_grab_expandably_bool
+ }
+ \bool_if:NTF \l_@@_long_bool
+ { \bool_set_true:N \l_@@_some_long_bool }
+ { \bool_set_true:N \l_@@_some_short_bool }
+ \tl_put_right:Nx \l_@@_arg_spec_tl
+ {
+ \bool_if:NT \l_@@_long_bool { + }
+ \bool_if:NT \l_@@_obey_spaces_bool { ! }
+ \exp_not:n {#1}
+ }
+ \bool_set_false:N \l_@@_long_bool
+ \bool_set_false:N \l_@@_obey_spaces_bool
+ }
+\cs_new_protected:Npn \@@_add_arg_spec_mandatory:n #1
+ {
+ \bool_if:NT \l_@@_some_obey_spaces_bool
+ {
+ \msg_error:nnxx { cmd } { non-trailing-obey-spaces }
+ { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+ \@@_bad_def:wn
+ }
+ \tl_clear:N \l_@@_last_delimiters_tl
+ \@@_add_arg_spec:n {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Preparing the signature: general mechanism}
+%
+% \begin{macro}{\@@_prepare_signature:n}
+% \begin{macro}{\@@_prepare_signature:N}
+% \begin{macro}{\@@_prepare_signature_bypass:N}
+% Actually creating the signature uses the same loop approach as
+% normalizing the signature. There are first a number of variables which need
+% to be set to track what is going on. Many of these variables are unused
+% when defining expandable commands.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_prepare_signature:n #1
+ {
+ \int_zero:N \l_@@_current_arg_int
+ \bool_set_false:N \l_@@_long_bool
+ \bool_set_false:N \l_@@_obey_spaces_bool
+ \int_zero:N \l_@@_m_args_int
+ \bool_set_false:N \l_@@_defaults_bool
+ \tl_clear:N \l_@@_defaults_tl
+ \tl_clear:N \l_@@_process_all_tl
+ \tl_clear:N \l_@@_process_one_tl
+ \bool_set_false:N \l_@@_process_some_bool
+ \tl_clear:N \l_@@_signature_tl
+ \@@_prepare_signature:N #1 \q_recursion_tail \q_recursion_stop
+ \bool_if:NF \l_@@_expandable_bool { \@@_flush_m_args: }
+ }
+% \end{macrocode}
+% The main looping function does not take an argument, but carries out the
+% reset on the processor boolean. This is split off from the rest of the
+% process so that when actually setting up processors the flag-reset can
+% be bypassed.
+%
+% For each known argument type there is an appropriate function to actually
+% do the addition to the signature. These are separate for expandable and
+% standard functions, as the approaches are different.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_prepare_signature:N
+ {
+ \bool_set_false:N \l_@@_prefixed_bool
+ \@@_prepare_signature_bypass:N
+ }
+\cs_new_protected:Npn \@@_prepare_signature_bypass:N #1
+ {
+ \quark_if_recursion_tail_stop:N #1
+ \use:c
+ {
+ @@_add
+ \bool_if:NT \l_@@_grab_expandably_bool { _expandable }
+ _type_ \token_to_str:N #1 :w
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Setting up a standard signature}
+%
+% Each argument-adding function appends to the signature a grabber (and
+% for some types, the delimiters or default value), except the one for
+% \texttt{m} arguments. These are collected and added to the signature
+% all at once by \cs{@@_flush_m_args:}, called for every other argument
+% type. All of the functions then call the loop function
+% \cs{@@_prepare_signature:N}. Default values of arguments are
+% collected by \cs{@@_add_default:n} rather than being stored with the
+% argument; this function and \cs{@@_add_default:} are also responsible
+% for keeping track of \cs{l_@@_current_arg_int}.
+%
+% \begin{macro}{\@@_add_type_+:w}
+% Making the next argument long means setting the flag. The \texttt{m}
+% arguments are recorded here as
+% this has to be done for every case where there is then a long argument.
+% \begin{macrocode}
+\cs_new_protected:cpn { @@_add_type_+:w }
+ {
+ \@@_flush_m_args:
+ \bool_set_true:N \l_@@_long_bool
+ \bool_set_true:N \l_@@_prefixed_bool
+ \@@_prepare_signature_bypass:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_!:w}
+% Much the same for controlling trailing optional arguments.
+% \begin{macrocode}
+\cs_new_protected:cpn { @@_add_type_!:w }
+ {
+ \@@_flush_m_args:
+ \bool_set_true:N \l_@@_obey_spaces_bool
+ \bool_set_true:N \l_@@_prefixed_bool
+ \@@_prepare_signature_bypass:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_>:w}
+% When a processor is found, the processor code is stored. It will be
+% used by \cs{@@_args_process:} once arguments are all found. Here too
+% the loop calls \cs{@@_prepare_signature_bypass:N} rather than
+% \cs{@@_prepare_signature:N} so that the flag is not reset.
+% \begin{macrocode}
+\cs_new_protected:cpn { @@_add_type_>:w } #1
+ {
+ \@@_flush_m_args:
+ \bool_set_true:N \l_@@_prefixed_bool
+ \bool_set_true:N \l_@@_process_some_bool
+ \tl_put_left:Nn \l_@@_process_one_tl { {#1} }
+ \@@_prepare_signature_bypass:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_b:w}
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_b:w
+ {
+ \@@_flush_m_args:
+ \@@_add_default:
+ \@@_add_grabber:N b
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_D:w}
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_D:w #1#2#3
+ {
+ \@@_flush_m_args:
+ \@@_add_default:n {#3}
+ \@@_add_grabber:N D
+ \tl_put_right:Nn \l_@@_signature_tl { #1 #2 }
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_E:w}
+% The \texttt{E}-type argument needs a special handling of default
+% values.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_E:w #1#2
+ {
+ \@@_flush_m_args:
+ \@@_add_default_E:nn {#1} {#2}
+ \@@_add_grabber:N E
+ \tl_put_right:Nn \l_@@_signature_tl { {#1} }
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_m:w}
+% The \texttt{m} type is special as short arguments which are not
+% post-processed are simply counted at this stage. Thus there is a check
+% to see if either of these cases apply. If so, a one-argument grabber
+% is added to the signature. On the other hand, if a standard short
+% argument is required it is simply counted at this stage, to be
+% added later using \cs{@@_flush_m_args:}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_m:w
+ {
+ \@@_add_default:
+ \bool_if:NTF \l_@@_prefixed_bool
+ { \@@_add_grabber:N m }
+ { \int_incr:N \l_@@_m_args_int }
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_R:w}
+% The \texttt{R}-type argument is very similar to the \texttt{D}-type.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_R:w #1#2#3
+ {
+ \@@_flush_m_args:
+ \@@_add_default:n {#3}
+ \@@_add_grabber:N R
+ \tl_put_right:Nn \l_@@_signature_tl { #1 #2 }
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_t:w}
+% Setting up a \texttt{t} argument means collecting one token for the test,
+% and adding it along with the grabber to the signature.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_t:w #1
+ {
+ \@@_flush_m_args:
+ \@@_add_default:
+ \@@_add_grabber:N t
+ \tl_put_right:Nn \l_@@_signature_tl {#1}
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_v:w}
+% At this stage, the \texttt{v} argument is identical to \texttt{l}
+% except that since the grabber may fail to read a verbatim argument
+% we need a default value.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_v:w
+ {
+ \@@_flush_m_args:
+ \exp_args:No \@@_add_default:n \c_novalue_tl
+ \@@_add_grabber:N v
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_flush_m_args:}
+% As \texttt{m} arguments are simply counted, there is a need to add
+% them to the token register in a block. As this function can only
+% be called if something other than \texttt{m} turns up, the flag can
+% be switched here.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_flush_m_args:
+ {
+ \int_compare:nNnT \l_@@_m_args_int > 0
+ {
+ \tl_put_right:Nx \l_@@_signature_tl
+ { \exp_not:c { @@_grab_m_ \int_use:N \l_@@_m_args_int :w } }
+ \tl_put_right:Nx \l_@@_process_all_tl
+ { \prg_replicate:nn { \l_@@_m_args_int } { { } } }
+ }
+ \int_zero:N \l_@@_m_args_int
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_grabber:N}
+% To keep the various checks needed in one place, adding the grabber
+% to the signature is done here. The only questions are whether the
+% grabber should be long or not, and whether to obey spaces. The
+% \cs{l_@@_obey_spaces_bool} boolean can only be \texttt{true} for
+% trailing optional arguments. In that case spaces will not be
+% ignored when looking for that optional argument.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_grabber:N #1
+ {
+ \tl_put_right:Nx \l_@@_signature_tl
+ {
+ \exp_not:c
+ {
+ @@_grab_ #1
+ \bool_if:NT \l_@@_long_bool { _long }
+ \bool_if:NT \l_@@_obey_spaces_bool { _obey_spaces }
+ :w
+ }
+ }
+ \bool_set_false:N \l_@@_long_bool
+ \bool_set_false:N \l_@@_obey_spaces_bool
+ \tl_put_right:Nx \l_@@_process_all_tl
+ { { \exp_not:o \l_@@_process_one_tl } }
+ \tl_clear:N \l_@@_process_one_tl
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_default:n, \@@_add_default:, \@@_add_default_E:nn}
+% Store the default value of an argument, or rather code that gives
+% that default value (it may involve other arguments). This is
+% \cs{c_novalue_tl} for arguments with no actual default or with
+% default |-NoValue-|; and (in a brace group) \cs{prg_do_nothing:}
+% followed by a default value for others. For \texttt{E}-type
+% arguments, pad the defaults |#2| with some \cs{c_novalue_tl}
+% until there are as many as embellishments~|#1|. These functions are
+% also used when defining expandable commands.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_default:n #1
+ {
+ \tl_if_novalue:nTF {#1}
+ { \@@_add_default: }
+ {
+ \int_incr:N \l_@@_current_arg_int
+ \bool_set_true:N \l_@@_defaults_bool
+ \tl_put_right:Nn \l_@@_defaults_tl { { \prg_do_nothing: #1 } }
+ }
+ }
+\cs_new_protected:Npn \@@_add_default:
+ {
+ \int_incr:N \l_@@_current_arg_int
+ \tl_put_right:Nn \l_@@_defaults_tl { \c_novalue_tl }
+ }
+\cs_new_protected:Npn \@@_add_default_E:nn #1#2
+ {
+ \tl_map_function:nN {#2} \@@_add_default:n
+ \prg_replicate:nn
+ { \tl_count:n {#1} - \tl_count:n {#2} }
+ { \@@_add_default: }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Setting up expandable types}
+%
+% The approach here is not dissimilar to that for standard types, but fewer types
+% are supported. There is
+% also a need to define the per-function auxiliaries: this is done here, while
+% the general grabbers are dealt with later.
+%
+% \begin{macro}{\@@_add_expandable_type_+:w}
+% We have already checked that short arguments are before long
+% arguments, so \cs{l_@@_long_bool} only changes from \texttt{false}
+% to \texttt{true} once (and there is no need to reset it after each
+% argument). Also knock back the argument count because |+| is not an
+% argument. Continue the loop.
+% \begin{macrocode}
+\cs_new_protected:cpn { @@_add_expandable_type_+:w }
+ {
+ \bool_set_true:N \l_@@_long_bool
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_D:w}
+% \begin{macro}{\@@_add_expandable_type_D_aux:NNNn}
+% \begin{macro}{\@@_add_expandable_type_D_aux:NNN}
+% \begin{macro}{\@@_add_expandable_type_D_aux:NN}
+% The set up for \texttt{D}-type arguments involves constructing a
+% rather complex auxiliary which is used
+% repeatedly when grabbing. There is an auxiliary here so that the
+% \texttt{R}-type can share code readily: |#1| is |D| or~|R|.
+% The |_aux:NN| auxiliary is needed if the two delimiting tokens are
+% identical: in contrast to the non-expandable route, the grabber here
+% has to act differently for this case.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_D:w
+ { \@@_add_expandable_type_D_aux:NNNn D }
+\cs_new_protected:Npn \@@_add_expandable_type_D_aux:NNNn #1#2#3#4
+ {
+ \@@_add_default:n {#4}
+ \tl_if_eq:nnTF {#2} {#3}
+ { \@@_add_expandable_type_D_aux:NN #1 #2 }
+ { \@@_add_expandable_type_D_aux:NNN #1 #2 #3 }
+ \@@_prepare_signature:N
+ }
+\cs_new_protected:Npn \@@_add_expandable_type_D_aux:NNN #1#2#3
+ {
+ \bool_if:NTF \l_@@_long_bool
+ { \cs_set:cpx }
+ { \cs_set_nopar:cpx }
+ { \l_@@_expandable_aux_name_tl } ##1 ##2 #2 ##3 \q_@@ ##4 #3
+ { ##1 {##2} {##3} {##4} }
+ \@@_add_expandable_grabber:nn {#1}
+ {
+ \exp_not:c { \l_@@_expandable_aux_name_tl }
+ \exp_not:n { #2 #3 }
+ }
+ }
+\cs_new_protected:Npn \@@_add_expandable_type_D_aux:NN #1#2
+ {
+ \bool_if:NTF \l_@@_long_bool
+ { \cs_set:cpx }
+ { \cs_set_nopar:cpx }
+ { \l_@@_expandable_aux_name_tl } ##1 #2 ##2 #2
+ { ##1 {##2} }
+ \@@_add_expandable_grabber:nn { #1_alt }
+ {
+ \exp_not:c { \l_@@_expandable_aux_name_tl }
+ \exp_not:n {#2}
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_E:w}
+% \begin{macro}{\@@_add_expandable_type_E_aux:n}
+% For each embellishment, use \cs{@@_get_grabber:NN} to obtain an
+% auxiliary delimited by that token and store a pair constituted of
+% the auxiliary and the token in \cs{l_@@_tmpb_tl}, before appending
+% the whole set of these pairs to the signature, and an equal number
+% of |-NoValue-| markers (regardless of the default values of
+% arguments). Set the current argument appropriately.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_E:w #1#2
+ {
+ \@@_add_default_E:nn {#1} {#2}
+ \tl_clear:N \l_@@_tmpb_tl
+ \tl_map_function:nN {#1} \@@_add_expandable_type_E_aux:n
+ \@@_add_expandable_grabber:nn
+ { E \bool_if:NT \l_@@_long_bool { _long } }
+ {
+ { \exp_not:o \l_@@_tmpb_tl }
+ {
+ \prg_replicate:nn { \tl_count:n {#1} }
+ { { \c_novalue_tl } }
+ }
+ }
+ \@@_prepare_signature:N
+ }
+\cs_new_protected:Npn \@@_add_expandable_type_E_aux:n #1
+ {
+ \@@_get_grabber:NN #1 \l_@@_tmpa_tl
+ \tl_put_right:Nx \l_@@_tmpb_tl
+ { \exp_not:o \l_@@_tmpa_tl \exp_not:N #1 }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_m:w}
+% Unlike the standard case, when working expandably each argument is always
+% grabbed separately.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_m:w
+ {
+ \@@_add_default:
+ \@@_add_expandable_grabber:nn
+ { m \bool_if:NT \l_@@_long_bool { _long } } { }
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_R:w}
+% The \texttt{R}-type is very similar to the \texttt{D}-type
+% argument, and so the same internals are used.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_R:w
+ { \@@_add_expandable_type_D_aux:NNNn R }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_t:w}
+% An auxiliary delimited by |#1| is built now. It will be used to
+% test for the presence of that token.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_t:w #1
+ {
+ \@@_add_default:
+ \@@_get_grabber:NN #1 \l_@@_tmpa_tl
+ \@@_add_expandable_grabber:nn { t }
+ {
+ \exp_not:o \l_@@_tmpa_tl
+ \exp_not:N #1
+ }
+ \@@_prepare_signature:N
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_grabber:nn}
+% This is called for all arguments to place the right grabber in the
+% signature.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_grabber:nn #1#2
+ {
+ \tl_put_right:Nx \l_@@_signature_tl
+ { \exp_not:c { @@_expandable_grab_ #1 :w } #2 }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_get_grabber:NN}
+% \begin{macro}{\@@_get_grabber_auxi:NN}
+% \begin{macro}{\@@_get_grabber_auxii:NN}
+% Given a token |#1|, defines an expandable function delimited by that
+% token and stores it in the token list~|#2|. The function is named
+% after the token, unless that function name is already taken by some
+% other grabber (this can happen in the rare case where delimiters
+% with different category codes are used in the same document): in
+% that case use a global counter to get a unique name. Since the
+% grabbers are not named after \pkg{xparse} commands they should not
+% be used to get material from the input stream.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_get_grabber:NN #1#2
+ {
+ \cs_set:Npn \@@_tmp:w ##1 #1 {##1}
+ \exp_args:Nc \@@_get_grabber_auxi:NN
+ { @@_grabber_ \token_to_str:N #1 :w } #2
+ }
+\cs_new_protected:Npn \@@_get_grabber_auxi:NN #1#2
+ {
+ \cs_if_eq:NNTF \@@_tmp:w #1
+ { \tl_set:Nn #2 {#1} }
+ {
+ \cs_if_exist:NTF #1
+ {
+ \int_gincr:N \g_@@_grabber_int
+ \exp_args:Nc \@@_get_grabber_auxi:NN
+ {
+ @@_grabber_
+ - \int_use:N \g_@@_grabber_int :w
+ }
+ #2
+ }
+ { \@@_get_grabber_auxii:NN #1 #2 }
+ }
+ }
+\cs_new_protected:Npn \@@_get_grabber_auxii:NN #1#2
+ {
+ \cs_set_eq:NN #1 \@@_tmp:w
+ \tl_set:Nn #2 {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Grabbing arguments}
+%
+% All of the grabbers follow the same basic pattern. The initial
+% function stores in \cs{l_@@_signature_tl} the code to grab further
+% arguments, defines (the function in) \cs{l_@@_fn_tl} that will grab
+% the argument, and calls it.
+%
+% Defining \cs{l_@@_fn_tl} means determining whether to use
+% \cs{cs_set:Npn} or \cs{cs_set_nopar:Npn}, and for optional arguments
+% whether to skip spaces. Once the argument is found, \cs{l_@@_fn_tl}
+% calls \cs{@@_add_arg:n}, responsible for calling processors and
+% grabbing further arguments.
+%
+% \begin{macro}
+% {
+% \@@_grab_b:w,
+% \@@_grab_b_long:w,
+% \@@_grab_b_obey_spaces:w,
+% \@@_grab_b_long_obey_spaces:w,
+% \@@_grab_b_aux:NNw,
+% \@@_grab_b_end:Nw
+% }
+% This uses the well-tested code of \texttt{D}-type arguments,
+% skipping the peeking step because the \texttt{b}-type argument is
+% always present, and adding a cleanup stage at the end by hijacking
+% the signature. The clean-up consists of properly
+% dealing with \cs{l_@@_args_tl} and also putting back the \cs{end}
+% that served as an end-delimiter: this \cs{end} receives the
+% environment name as its argument and is run normally. The
+% \texttt{D}-type code stores the argument found (body of the
+% environment) as a brace group in \cs{l_@@_args_tl} and depending on
+% the presence of a prefix~|!| we trim spaces or not before adding
+% this braced argument into the saved \cs{l_@@_args_tl}.
+% The strange \verb*|\begin | control sequence is there for display
+% purposes only: it has to look like |\begin| in the terminal but
+% not to delimited arguments.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_b:w
+ { \@@_grab_b_aux:NNw \cs_set_protected_nopar:Npn \tl_trim_spaces:n }
+\cs_new_protected:Npn \@@_grab_b_long:w
+ { \@@_grab_b_aux:NNw \cs_set_protected:Npn \tl_trim_spaces:n }
+\cs_new_protected:Npn \@@_grab_b_obey_spaces:w
+ { \@@_grab_b_aux:NNw \cs_set_protected_nopar:Npn \exp_not:n }
+\cs_new_protected:Npn \@@_grab_b_long_obey_spaces:w
+ { \@@_grab_b_aux:NNw \cs_set_protected:Npn \exp_not:n }
+\cs_new_protected:Npn \@@_grab_b_aux:NNw #1#2#3 \@@_run_code:
+ {
+ \@@_grab_D_aux:NNnN \begin \end {#3} #1
+ \tl_put_left:Nn \l_@@_signature_tl { \@@_grab_b_end:Nw #2 }
+ \tl_set_eq:NN \l_@@_saved_args_tl \l_@@_args_tl
+ \tl_clear:N \l_@@_args_tl
+ \exp_args:Nc \l_@@_fn_tl { begin ~ }
+ }
+\cs_new_protected:Npn \@@_grab_b_end:Nw #1#2 \@@_run_code:
+ {
+ \tl_set:Nx \l_@@_args_tl
+ {
+ \exp_not:V \l_@@_saved_args_tl
+ { \exp_after:wN #1 \l_@@_args_tl }
+ }
+ #2
+ \@@_run_code:
+ \end
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_D:w}
+% \begin{macro}{\@@_grab_D_long:w}
+% \begin{macro}{\@@_grab_D_obey_spaces:w}
+% \begin{macro}{\@@_grab_D_long_obey_spaces:w}
+% The generic delimited argument grabber. The auxiliary function does
+% a peek test before calling \cs{@@_grab_D_call:Nw}, so that the
+% optional nature of the argument works as expected.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_D:w #1#2#3 \@@_run_code:
+ {
+ \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected_nopar:Npn
+ \@@_peek_nonspace_remove:NTF
+ }
+\cs_new_protected:Npn \@@_grab_D_long:w #1#2#3 \@@_run_code:
+ {
+ \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected:Npn
+ \@@_peek_nonspace_remove:NTF
+ }
+\cs_new_protected:Npn \@@_grab_D_obey_spaces:w #1#2#3 \@@_run_code:
+ {
+ \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected_nopar:Npn
+ \@@_peek_meaning_remove:NTF
+ }
+\cs_new_protected:Npn \@@_grab_D_long_obey_spaces:w #1#2#3 \@@_run_code:
+ {
+ \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected:Npn
+ \@@_peek_meaning_remove:NTF
+ }
+% \end{macrocode}
+% \begin{macro}{\@@_grab_D_aux:NNnNN}
+% \begin{macro}{\@@_grab_D_aux:NNnN}
+% This is a bit complicated. The idea is that, in order to check for
+% nested optional argument tokens (\texttt{[[...]]} and so on) the
+% argument needs to be grabbed without removing any braces at all. If
+% this is not done, then cases like |[{[}]| fail. So after testing for
+% an optional argument, it is collected piece-wise. Inserting a quark
+% prevents loss of braces, and there is then a test to see if there are
+% nested delimiters to handle.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_D_aux:NNnNN #1#2#3#4#5
+ {
+ \@@_grab_D_aux:NNnN #1#2 {#3} #4
+ #5 #1
+ { \@@_grab_D_call:Nw #1 }
+ { \@@_add_arg:o \c_novalue_tl }
+ }
+% \end{macrocode}
+% Inside the \enquote{standard} grabber, there is a test to see if the
+% grabbed argument is entirely enclosed by braces. There are a couple of
+% extra factors to allow for: the argument might be entirely empty, and
+% spaces at the start and end of the input must be retained around a brace
+% group. Also notice that a \emph{blank} argument might still contain
+% spaces.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_D_aux:NNnN #1#2#3#4
+ {
+ \tl_set:Nn \l_@@_signature_tl {#3}
+ \exp_after:wN #4 \l_@@_fn_tl ##1 #2
+ {
+ \tl_if_in:nnTF {##1} {#1}
+ { \@@_grab_D_nested:NNnN #1 #2 {##1} #4 }
+ {
+ \tl_if_blank:oTF { \use_none:n ##1 }
+ { \@@_add_arg:o { \use_none:n ##1 } }
+ {
+ \str_if_eq:eeTF
+ { \exp_not:o { \use_none:n ##1 } }
+ { { \exp_not:o { \use_ii:nnn ##1 \q_nil } } }
+ { \@@_add_arg:o { \use_ii:nn ##1 } }
+ { \@@_add_arg:o { \use_none:n ##1 } }
+ }
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \begin{macro}{\@@_grab_D_nested:NNnN}
+% \begin{macro}{\@@_grab_D_nested:w}
+% \begin{macro}{\l_@@_nesting_a_tl}
+% \begin{macro}{\l_@@_nesting_b_tl}
+% \begin{macro}{\q_@@}
+% Catching nested optional arguments means more work. The aim here is
+% to collect up each pair of optional tokens without \TeX{} helping out,
+% and without counting anything. The code above will already have
+% removed the leading opening token and a closing token, but the
+% wrong one. The aim is then to work through the material grabbed
+% so far and divide it up on each opening token, grabbing a closing
+% token to match (thus working in pairs). Once there are no opening
+% tokens, then there is a second check to see if there are any
+% opening tokens in the second part of the argument (for things
+% like |[][]|). Once everything has been found, the entire collected
+% material is added to the output as a single argument. The only tricky part
+% here is ensuring that any grabbing function that might run away is named
+% after the function currently being parsed and not after \pkg{xparse}. That
+% leads to some rather complex nesting! There is also a need to prevent the
+% loss of any braces, hence the insertion and removal of quarks along the
+% way.
+% \begin{macrocode}
+\tl_new:N \l_@@_nesting_a_tl
+\tl_new:N \l_@@_nesting_b_tl
+\quark_new:N \q_@@
+\cs_new_protected:Npn \@@_grab_D_nested:NNnN #1#2#3#4
+ {
+ \tl_clear:N \l_@@_nesting_a_tl
+ \tl_clear:N \l_@@_nesting_b_tl
+ \exp_after:wN #4 \l_@@_fn_tl ##1 #1 ##2 \q_@@ ##3 #2
+ {
+ \tl_put_right:No \l_@@_nesting_a_tl { \use_none:n ##1 #1 }
+ \tl_put_right:No \l_@@_nesting_b_tl { \use_i:nn #2 ##3 }
+ \tl_if_in:nnTF {##2} {#1}
+ {
+ \l_@@_fn_tl
+ \q_nil ##2 \q_@@ \ERROR
+ }
+ {
+ \tl_put_right:Nx \l_@@_nesting_a_tl
+ { \@@_grab_D_nested:w \q_nil ##2 \q_stop }
+ \tl_if_in:NnTF \l_@@_nesting_b_tl {#1}
+ {
+ \tl_set_eq:NN \l_@@_tmpa_tl \l_@@_nesting_b_tl
+ \tl_clear:N \l_@@_nesting_b_tl
+ \exp_after:wN \l_@@_fn_tl \exp_after:wN
+ \q_nil \l_@@_tmpa_tl \q_nil \q_@@ \ERROR
+ }
+ {
+ \tl_put_right:No \l_@@_nesting_a_tl
+ \l_@@_nesting_b_tl
+ \@@_add_arg:V \l_@@_nesting_a_tl
+ }
+ }
+ }
+ \l_@@_fn_tl #3 \q_nil \q_@@ \ERROR
+ }
+\cs_new:Npn \@@_grab_D_nested:w #1 \q_nil \q_stop
+ { \exp_not:o { \use_none:n #1 } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \begin{macro}{\@@_grab_D_call:Nw}
+% For \texttt{D} and \texttt{R}-type arguments, to avoid losing any
+% braces, a token needs to be inserted before the argument to be grabbed.
+% If the argument runs away because the closing token is missing then this
+% inserted token shows up in the terminal. Ideally, |#1| would therefore be
+% used directly, but that is no good as it will mess up the rest of the
+% grabber. Instead, a copy of |#1| with an altered category code is used,
+% as this will look right in the terminal but will not mess up the grabber.
+% The only issue then is that the category code of |#1| is unknown. So there
+% is a quick test to ensure that the inserted token can never be matched by
+% the grabber. (This assumes that the open and close delimiters are not the
+% same character with different category codes, but that really should not
+% happen in any sensible document-level syntax.)
+% An exception is when |#1| is a control sequence token, in which case the
+% character-token treatment is no good because if hit with \cs{token_to_str:N}
+% it would add sputios tokens to the argument. In this case a different
+% branch is taken. The token inserted is then the same \meta{csname} as |#1|,
+% but with a space appended, so that the grabber don't see it as another
+% of the same delimiter.
+% \begin{macrocode}
+\cs_new_protected_nopar:Npn \@@_grab_D_call:Nw #1
+ {
+ \token_if_eq_catcode:NNTF + #1
+ {
+ \exp_after:wN \exp_after:wN \exp_after:wN
+ \l_@@_fn_tl \char_generate:nn { `#1 } { 11 }
+ }
+ {
+ \@@_token_if_cs:NTF #1
+ {
+ \exp_after:wN \l_@@_fn_tl
+ \cs:w \cs_to_str:N #1 ~ \cs_end:
+ }
+ {
+ \exp_after:wN \l_@@_fn_tl
+ \token_to_str:N #1
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_grab_E:w, \@@_grab_E_long:w,
+% \@@_grab_E_obey_spaces:w, \@@_grab_E_long_obey_spaces:w
+% }
+% \begin{macro}{\@@_grab_E:nnNN}
+% \begin{macro}{\@@_grab_E_loop:NnN}
+% \begin{macro}{\@@_grab_E_finalise:}
+% Everything here needs to point to a loop.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_E:w #1#2 \@@_run_code:
+ {
+ \@@_grab_E:nnNN {#1} {#2}
+ \cs_set_protected_nopar:Npn
+ \@@_peek_nonspace_remove:NTF
+ }
+\cs_new_protected:Npn \@@_grab_E_long:w #1#2 \@@_run_code:
+ {
+ \@@_grab_E:nnNN {#1} {#2}
+ \cs_set_protected:Npn
+ \@@_peek_nonspace_remove:NTF
+ }
+\cs_new_protected:Npn \@@_grab_E_obey_spaces:w #1#2 \@@_run_code:
+ {
+ \@@_grab_E:nnNN {#1} {#2}
+ \cs_set_protected_nopar:Npn
+ \@@_peek_meaning_remove:NTF
+ }
+\cs_new_protected:Npn \@@_grab_E_long_obey_spaces:w #1#2 \@@_run_code:
+ {
+ \@@_grab_E:nnNN {#1} {#2}
+ \cs_set_protected:Npn
+ \@@_peek_meaning_remove:NTF
+ }
+% \end{macrocode}
+% A loop is needed here to allow a random ordering of keys. These are
+% searched for one at a time, with any not found needing to be tracked:
+% they can appear later. The grabbed values are held in a property list
+% which is then turned into an ordered list to be passed back to the user.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_E:nnNN #1#2#3#4
+ {
+ \exp_after:wN #3 \l_@@_fn_tl ##1##2##3
+ {
+ \prop_put:Nnn \l_@@_tmp_prop {##1} {##3}
+ \@@_grab_E_loop:NnN #4 { } ##2 \q_recursion_stop
+ }
+ \prop_clear:N \l_@@_tmp_prop
+ \tl_set:Nn \l_@@_signature_tl {#2}
+ \cs_set_protected:Npn \@@_grab_E_finalise:
+ {
+ \tl_map_inline:nn {#1}
+ {
+ \prop_get:NnNF \l_@@_tmp_prop {####1} \l_@@_tmpb_tl
+ { \tl_set_eq:NN \l_@@_tmpb_tl \c_novalue_tl }
+ \tl_put_right:Nx \l_@@_args_tl
+ { { \exp_not:V \l_@@_tmpb_tl } }
+ }
+ \l_@@_signature_tl \@@_run_code:
+ }
+ \@@_grab_E_loop:NnN #4 { } #1 \q_recursion_tail \q_recursion_stop
+ }
+\cs_new_protected:Npn \@@_grab_E_loop:NnN #1#2#3#4 \q_recursion_stop
+ {
+ \cs_if_eq:NNTF #3 \q_recursion_tail
+ { \@@_grab_E_finalise: }
+ {
+ #1 #3
+ { \l_@@_fn_tl #3 {#2#4} }
+ { \@@_grab_E_loop:NnN #1 {#2#3} #4 \q_recursion_stop }
+ }
+ }
+\cs_new_protected:Npn \@@_grab_E_finalise: { }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+%
+% \begin{macro}{\@@_grab_m:w}
+% \begin{macro}{\@@_grab_m_long:w}
+% Collecting a single mandatory argument is quite easy.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_m:w #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_protected_nopar:Npn \l_@@_fn_tl ##1
+ { \@@_add_arg:n {##1} }
+ \l_@@_fn_tl
+ }
+\cs_new_protected:Npn \@@_grab_m_long:w #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_protected:Npn \l_@@_fn_tl ##1
+ { \@@_add_arg:n {##1} }
+ \l_@@_fn_tl
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_m_1:w}
+% \begin{macro}{\@@_grab_m_2:w}
+% \begin{macro}{\@@_grab_m_3:w}
+% \begin{macro}{\@@_grab_m_4:w}
+% \begin{macro}{\@@_grab_m_5:w}
+% \begin{macro}{\@@_grab_m_6:w}
+% \begin{macro}{\@@_grab_m_7:w}
+% \begin{macro}{\@@_grab_m_8:w}
+% \begin{macro}{\@@_grab_m_9:w}
+% \begin{macro}{\@@_grab_m_aux:Nnnnnnnnn}
+% Grabbing 1--8 mandatory arguments is done by giving 8--1 known
+% arguments to a 9-argument function that stores them in
+% \cs{l_@@_args_tl}. For simplicity, grabbing 9 mandatory arguments
+% is done by grabbing 5 then 4 arguments.
+% \begin{macrocode}
+\cs_new_protected_nopar:Npn \@@_grab_m_aux:Nnnnnnnnn #1#2#3#4#5#6#7#8#9
+ {
+ \tl_put_right:No \l_@@_args_tl
+ { #1 {#2} {#3} {#4} {#5} {#6} {#7} {#8} {#9} }
+ \l_@@_signature_tl \@@_run_code:
+ }
+\cs_new_protected:cpn { @@_grab_m_1:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \use_none:nnnnnnn { } { } { } { } { } { } { }
+ }
+\cs_new_protected:cpn { @@_grab_m_2:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \use_none:nnnnnn { } { } { } { } { } { }
+ }
+\cs_new_protected:cpn { @@_grab_m_3:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \use_none:nnnnn { } { } { } { } { }
+ }
+\cs_new_protected:cpn { @@_grab_m_4:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \use_none:nnnn { } { } { } { }
+ }
+\cs_new_protected:cpn { @@_grab_m_5:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \use_none:nnn { } { } { }
+ }
+\cs_new_protected:cpn { @@_grab_m_6:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \use_none:nn { } { }
+ }
+\cs_new_protected:cpn { @@_grab_m_7:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \use_none:n { }
+ }
+\cs_new_protected:cpn { @@_grab_m_8:w } #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+ \l_@@_fn_tl \prg_do_nothing:
+ }
+\cs_new_protected:cpx { @@_grab_m_9:w }
+ {
+ \exp_not:c { @@_grab_m_5:w }
+ \exp_not:c { @@_grab_m_4:w }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_R:w, \@@_grab_R_long:w}
+% \begin{macro}{\@@_grab_R_aux:NNnN}
+% The grabber for \texttt{R}-type arguments is basically the same as
+% that for \texttt{D}-type ones, but always skips spaces (as it is mandatory)
+% and has a hard-coded error message.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_R:w #1#2#3 \@@_run_code:
+ { \@@_grab_R_aux:NNnN #1 #2 {#3} \cs_set_protected_nopar:Npn }
+\cs_new_protected:Npn \@@_grab_R_long:w #1#2#3 \@@_run_code:
+ { \@@_grab_R_aux:NNnN #1 #2 {#3} \cs_set_protected:Npn }
+\cs_new_protected:Npn \@@_grab_R_aux:NNnN #1#2#3#4
+ {
+ \@@_grab_D_aux:NNnN #1 #2 {#3} #4
+ \@@_peek_nonspace_remove:NTF #1
+ { \@@_grab_D_call:Nw #1 }
+ {
+ \msg_error:nnxx { cmd } { missing-required }
+ { \@@_environment_or_command: }
+ { \token_to_str:N #1 }
+ \@@_add_arg:o \c_novalue_tl
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_t:w}
+% \begin{macro}{\@@_grab_t_obey_spaces:w}
+% \begin{macro}{\@@_grab_t_aux:NNw}
+% Dealing with a token is quite easy. Check the match, remove the
+% token if needed and add a flag to the output.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_t:w
+ { \@@_grab_t_aux:NNw \@@_peek_nonspace_remove:NTF }
+\cs_new_protected:Npn \@@_grab_t_obey_spaces:w
+ { \@@_grab_t_aux:NNw \@@_peek_meaning_remove:NTF }
+\cs_new_protected:Npn \@@_grab_t_aux:NNw #1#2#3 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#3}
+ \exp_after:wN \cs_set_protected:Npn \l_@@_fn_tl
+ {
+ #1 #2
+ { \@@_add_arg:n { \BooleanTrue } }
+ { \@@_add_arg:n { \BooleanFalse } }
+ }
+ \l_@@_fn_tl
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{variable}{\l_@@_v_arg_tl}
+% \begin{macrocode}
+\tl_new:N \l_@@_v_arg_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_grab_v:w}
+% \begin{macro}{\@@_grab_v_long:w}
+% \begin{macro}{\@@_grab_v_aux:w}
+% \begin{macro}{\@@_grab_v_group_end:}
+% The opening delimiter is the first non-space token, and is never
+% read verbatim. This is required by consistency with the case where
+% the preceding argument was optional and absent: then \TeX{} has
+% already read and tokenized that token when looking for the optional
+% argument. The first thing is thus to check is that this delimiter
+% is a character, and to distinguish the case of a left brace (in that
+% case, \cs{group_align_safe_end:} is needed to compensate for the
+% begin-group character that was just seen). Then set verbatim
+% catcodes with \cs{@@_grab_v_aux_catcodes:}.
+%
+% The group keep catcode changes local, and
+% \cs{group_align_safe_begin/end:} allow to use a character
+% with category code~$4$ (normally |&|) as the delimiter (all commands
+% do \cs{group_align_safe_begin/end:}, so there's no need to do that
+% again here).
+% It is ended by \cs{@@_grab_v_group_end:}, which smuggles
+% the collected argument out of the group.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v:w
+ {
+ \bool_set_false:N \l_@@_long_bool
+ \@@_grab_v_aux:w
+ }
+\cs_new_protected:Npn \@@_grab_v_long:w
+ {
+ \bool_set_true:N \l_@@_long_bool
+ \@@_grab_v_aux:w
+ }
+\cs_new_protected:Npn \@@_grab_v_aux:w #1 \@@_run_code:
+ {
+ \tl_set:Nn \l_@@_signature_tl {#1}
+ \group_begin:
+ \tex_escapechar:D = 92 \scan_stop:
+ \tl_clear:N \l_@@_v_arg_tl
+ \peek_remove_spaces:n
+ {
+ \peek_meaning_remove:NTF \c_group_begin_token
+ {
+ \group_align_safe_end:
+ \@@_grab_v_bgroup:
+ }
+ {
+ \peek_N_type:TF
+ { \@@_grab_v_aux_test:N }
+ { \@@_grab_v_aux_abort:n { } }
+ }
+ }
+ }
+\cs_new_protected:Npn \@@_grab_v_group_end:
+ {
+ \exp_args:NNNo
+ \group_end:
+ \tl_set:Nn \l_@@_v_arg_tl { \l_@@_v_arg_tl }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_aux_test:N}
+% \begin{macro}
+% {
+% \@@_grab_v_aux_loop:N,
+% \@@_grab_v_aux_loop:NN,
+% \@@_grab_v_aux_loop_end:
+% }
+% Check that the opening delimiter is a character, setup category codes,
+% then start reading tokens one by one, keeping the delimiter as an argument.
+% If the verbatim was not nested, we will be grabbing one character
+% at each step. Unfortunately, it can happen that what follows the
+% verbatim argument is already tokenized. Thus, we check at each step
+% that the next token is indeed a \enquote{nice}
+% character, \emph{i.e.}, is not a character with
+% category code $1$ (begin-group), $2$ (end-group)
+% or $6$ (macro parameter), nor the space character,
+% with category code~$10$ and character code~$32$,
+% nor a control sequence.
+% The partially built argument is stored in \cs{l_@@_v_arg_tl}.
+% If we ever meet a token which we cannot grab (non-N-type),
+% or which is not a character according to
+% \cs{@@_grab_v_token_if_char:NTF}, then we bail out with
+% \cs{@@_grab_v_aux_abort:n}. Otherwise, we stop at the first
+% character matching the delimiter.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_aux_test:N #1
+ {
+ \@@_grab_v_token_if_char:NTF #1
+ {
+ \@@_grab_v_aux_put:N #1
+ \@@_grab_v_aux_catcodes:
+ \@@_grab_v_aux_loop:N #1
+ }
+ { \@@_grab_v_aux_abort:n {#1} #1 }
+ }
+\cs_new_protected:Npn \@@_grab_v_aux_loop:N #1
+ {
+ \peek_N_type:TF
+ { \@@_grab_v_aux_loop:NN #1 }
+ { \@@_grab_v_aux_abort:n { } }
+ }
+\cs_new_protected:Npn \@@_grab_v_aux_loop:NN #1#2
+ {
+ \@@_grab_v_token_if_char:NTF #2
+ {
+ \token_if_eq_charcode:NNTF #1 #2
+ { \@@_grab_v_aux_loop_end: }
+ {
+ \@@_grab_v_aux_put:N #2
+ \@@_grab_v_aux_loop:N #1
+ }
+ }
+ { \@@_grab_v_aux_abort:n {#2} #2 }
+ }
+\cs_new_protected:Npn \@@_grab_v_aux_loop_end:
+ {
+ \@@_grab_v_group_end:
+ \@@_add_arg:x { \tl_tail:N \l_@@_v_arg_tl }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{variable}{\l_@@_v_nesting_int}
+% \begin{macrocode}
+\int_new:N \l_@@_v_nesting_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_grab_v_bgroup:}
+% \begin{macro}{\@@_grab_v_bgroup_loop:}
+% \begin{macro}{\@@_grab_v_bgroup_loop:N}
+% If the opening delimiter is a left brace, we keep track of
+% how many left and right braces were encountered so far in
+% \cs{l_@@_v_nesting_int} (the methods used for optional
+% arguments cannot apply here), and stop as soon as it reaches~$0$.
+%
+% Some care was needed when removing the opening delimiter, which
+% has already been assigned category code~$1$: using
+% \cs{peek_meaning_remove:NTF} in the \cs{@@_grab_v_aux:w}
+% function would break within alignments. Instead, we first
+% convert that token to a string, and remove the result as a
+% normal undelimited argument.
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_grab_v_bgroup:
+ {
+ \exp_not:N \@@_grab_v_aux_catcodes:
+ \exp_not:n { \int_set:Nn \l_@@_v_nesting_int { 1 } }
+ \exp_not:N \@@_grab_v_aux_put:N \iow_char:N \{
+ \exp_not:N \@@_grab_v_bgroup_loop:
+ }
+\cs_new_protected:Npn \@@_grab_v_bgroup_loop:
+ {
+ \peek_N_type:TF
+ { \@@_grab_v_bgroup_loop:N }
+ { \@@_grab_v_aux_abort:n { } }
+ }
+\cs_new_protected:Npn \@@_grab_v_bgroup_loop:N #1
+ {
+ \@@_grab_v_token_if_char:NTF #1
+ {
+ \token_if_eq_charcode:NNTF \c_group_end_token #1
+ {
+ \int_decr:N \l_@@_v_nesting_int
+ \int_compare:nNnTF \l_@@_v_nesting_int > 0
+ {
+ \@@_grab_v_aux_put:N #1
+ \@@_grab_v_bgroup_loop:
+ }
+ { \@@_grab_v_aux_loop_end: }
+ }
+ {
+ \token_if_eq_charcode:NNT \c_group_begin_token #1
+ { \int_incr:N \l_@@_v_nesting_int }
+ \@@_grab_v_aux_put:N #1
+ \@@_grab_v_bgroup_loop:
+ }
+ }
+ { \@@_grab_v_aux_abort:n {#1} #1 }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_aux_catcodes:}
+% \begin{macro}{\@@_grab_v_aux_abort:n}
+% The approach for short verbatim arguments is to make the end-line
+% character a macro parameter character: this is forbidden by the
+% rest of the code. Then the error branch can check what caused the
+% bail out and give the appropriate error message.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_aux_catcodes:
+ {
+ \cs_set_eq:NN \do \char_set_catcode_other:N
+ \dospecials
+ \tex_endlinechar:D = `\^^M \scan_stop:
+ \bool_if:NTF \l_@@_long_bool
+ { \char_set_catcode_other:n { \tex_endlinechar:D } }
+ { \char_set_catcode_parameter:n { \tex_endlinechar:D } }
+ }
+\cs_new_protected:Npn \@@_grab_v_aux_abort:n #1
+ {
+ \@@_grab_v_group_end:
+ \exp_after:wN \exp_after:wN \exp_after:wN
+ \peek_meaning_remove:NTF \char_generate:nn { \tex_endlinechar:D } { 6 }
+ {
+ \msg_error:nnxxx { cmd } { verbatim-newline }
+ { \@@_environment_or_command: }
+ { \tl_to_str:N \l_@@_v_arg_tl }
+ { \tl_to_str:n {#1} }
+ \@@_add_arg:o \c_novalue_tl
+ }
+ {
+ \msg_error:nnxxx { cmd } { verbatim-tokenized }
+ { \@@_environment_or_command: }
+ { \tl_to_str:N \l_@@_v_arg_tl }
+ { \tl_to_str:n {#1} }
+ \@@_add_arg:o \c_novalue_tl
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_aux_put:N}
+% Storing one token in the collected argument. Most tokens are
+% converted to category code $12$, with the exception of active
+% characters, and spaces (not sure what should be done for those).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_aux_put:N #1
+ {
+ \tl_put_right:Nx \l_@@_v_arg_tl
+ {
+ \token_if_active:NTF #1
+ { \exp_not:N #1 } { \token_to_str:N #1 }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_token_if_char:NTF}
+% This function assumes that the escape character is printable.
+% Then the string representation of control sequences is at least
+% two characters, and \cs{str_tail:n} only removes the escape
+% character. Macro parameter characters are doubled by
+% \cs{tl_to_str:n}, and will also yield a non-empty result,
+% hence are not considered as characters.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_token_if_char:NTF #1
+ { \str_if_eq:eeTF { } { \str_tail:n {#1} } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_arg:n, \@@_add_arg:V, \@@_add_arg:o, \@@_add_arg:x}
+% When an argument is found it is stored, then further arguments are
+% grabbed by calling \cs{l_@@_signature_tl}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_add_arg:n #1
+ {
+ \tl_put_right:Nn \l_@@_args_tl { {#1} }
+ \l_@@_signature_tl \@@_run_code:
+ }
+\cs_generate_variant:Nn \@@_add_arg:n { V , o , x }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Grabbing arguments expandably}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_D:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:NNNwNNn}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:NNNwNNnnn}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:Nw}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:nnNNNwNN}
+% The first step is to grab the first token or group. The generic grabbers
+% \cs{\meta{function}}\verb*| | and \cs{\meta{function}}\verb*| | are just after \cs{q_@@}, we go and find
+% them (and use the long one).
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D:w #1 \q_@@ #2#3
+ { #2 { \@@_expandable_grab_D:NNNwNNn #1 \q_@@ #2 #3 } }
+% \end{macrocode}
+% We then wish to test whether |#7|, which we just grabbed, is exactly |#2|.
+% A preliminary test is whether their string representations coincide, then
+% expand the only grabber function we have, |#1|, once: the two strings below
+% are equal if and only if |#7| matches |#2| exactly.\footnote{It is obvious
+% that if \texttt{\#7} matches \texttt{\#2} then the strings are equal. We
+% must check the converse. The right-hand-side of \cs{str_if_eq:onTF} does
+% not end with \texttt{\#3}, implying that the grabber function took
+% everything as its arguments. The first brace group can only be empty if
+% \texttt{\#7} starts with \texttt{\#2}, otherwise the brace group preceding
+% \texttt{\#7} would not vanish. The third brace group is empty, thus the
+% \cs{q_@@} that was used by our grabber \texttt{\#1} must be the one
+% that we inserted (not some token in \texttt{\#7}), hence the second brace
+% group contains the end of \texttt{\#7} followed by \texttt{\#2}. Since this
+% is \texttt{\#2} on the right-hand-side, and no brace can be lost there,
+% \texttt{\#7} must contain nothing else than its leading \texttt{\#2}.}
+% The preliminary test is needed as |#7| could validly contain
+% \tn{par} (because a later mandatory argument could be long) and our
+% grabber may be short. If
+% |#7| does not match |#2|, then the optional argument is missing, we use the
+% default |-NoValue-|, and put back the argument |#7| in the input stream.
+%
+% If it does match, then interesting things need to be done. We will grab the
+% argument piece by piece, with the following pattern:
+% \begin{quote}
+% \meta{grabber} \Arg{tokens} \\
+% ~~\cs{q_nil} \Arg{piece 1} \meta{piece 2} \cs{ERROR} \cs{q_@@}\\
+% ~~\cs{q_nil} \meta{input stream}
+% \end{quote}
+% The \meta{grabber} will find an opening delimiter in \meta{piece 2}, take
+% the \cs{q_@@} as a second delimiter, and find more material delimited
+% by the closing delimiter in the \meta{input stream}. We then move the part
+% before the opening delimiter from \meta{piece 2} to \meta{piece 1}, and the
+% material taken from the \meta{input stream} to the \meta{piece 2}. Thus,
+% the argument moves gradually from the \meta{input stream} to the
+% \meta{piece 2}, then to the \meta{piece 1} when we have made sure to find
+% all opening and closing delimiters. This two-step process ensures that
+% nesting works: the number of opening delimiters minus closing delimiters in
+% \meta{piece 1} is always equal to the number of closing delimiters in
+% \meta{piece 2}. We stop grabbing arguments once the \meta{piece 2} contains
+% no opening delimiter any more, hence the balance is reached, and the final
+% argument is \meta{piece 1} \meta{piece 2}.
+% The indirection via \cs{@@_tmp:w} allows to insert |-NoValue-| expanded.
+% \begin{macrocode}
+\cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new:Npn \@@_expandable_grab_D:NNNwNNn ##1##2##3##4 \q_@@ ##5##6##7
+ {
+ \str_if_eq:nnTF {##2} {##7}
+ {
+ \str_if_eq:onTF
+ { ##1 { } { } ##7 ##2 \q_@@ ##3 }
+ { { } {##2} { } }
+ }
+ { \use_ii:nn }
+ {
+ ##1
+ { \@@_expandable_grab_D:NNNwNNnnn ##1##2##3##4 \q_@@ ##5##6 }
+ \q_nil { } ##2 \ERROR \q_@@ \ERROR
+ }
+ { ##4 {#1} \q_@@ ##5 ##6 {##7} }
+ }
+ }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+% \end{macrocode}
+% At this stage, |#7| is \cs{q_nil} \Arg{piece 1} \meta{more for piece 1},
+% and we want to concatenate all that, removing \cs{q_nil}, and keeping the
+% opening delimiter |#2|. Simply use \cs{use_ii:nn}. Also, |#8| is
+% \meta{remainder of piece 2} \cs{ERROR}, and |#9| is \cs{ERROR} \meta{more
+% for piece 2}. We concatenate those, replacing the two \cs{ERROR} by the
+% closing delimiter |#3|.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D:NNNwNNnnn #1#2#3#4 \q_@@ #5#6#7#8#9
+ {
+ \exp_args:Nof \@@_expandable_grab_D:nnNNNwNN
+ { \use_ii:nn #7 #2 }
+ { \@@_expandable_grab_D:Nw #3 \exp_stop_f: #8 #9 }
+ #1#2#3 #4 \q_@@ #5 #6
+ }
+\cs_new:Npn \@@_expandable_grab_D:Nw #1#2 \ERROR \ERROR { #2 #1 }
+% \end{macrocode}
+% Armed with our two new \meta{pieces}, we are ready to loop. However, we
+% must first see if \meta{piece 2} (here |#2|) contains any opening
+% delimiter |#4|. Again, we expand |#3|, this time removing its whole output
+% with \cs{use_none:nnn}. The test is similar to \cs{tl_if_in:nnTF}. The
+% token list is empty if and only if |#2| does not contain the opening
+% delimiter. In that case, we are done, and put the argument (from which we
+% remove a spurious pair of delimiters coming from how we started the loop).
+% Otherwise, we go back to looping with
+% \cs{@@_expandable_grab_D:NNNwNNnnn}. The code to deal with brace stripping
+% is much the same as for the non-expandable case.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D:nnNNNwNN #1#2#3#4#5#6 \q_@@ #7#8
+ {
+ \exp_args:No \tl_if_empty:oTF
+ { #3 { \use_none:nnn } #2 \q_@@ #5 #4 \q_@@ #5 }
+ {
+ \tl_if_blank:oTF { \use_none:nn #1#2 }
+ { \@@_put_arg_expandable:ow { \use_none:nn #1#2 } }
+ {
+ \str_if_eq:eeTF
+ { \exp_not:o { \use_none:nn #1#2 } }
+ { { \exp_not:o { \use_iii:nnnn #1#2 \q_nil } } }
+ { \@@_put_arg_expandable:ow { \use_iii:nnn #1#2 } }
+ { \@@_put_arg_expandable:ow { \use_none:nn #1#2 } }
+ }
+ #6 \q_@@ #7 #8
+ }
+ {
+ #3
+ { \@@_expandable_grab_D:NNNwNNnnn #3#4#5#6 \q_@@ #7 #8 }
+ \q_nil {#1} #2 \ERROR \q_@@ \ERROR
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_D_alt:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_D_alt:NNwNNn}
+% \begin{macro}[EXP]{\@@_expandable_grab_D_alt:Nwn}
+% When the delimiters are identical, nesting is not possible and a simplified
+% approach is used. The test concept here is the same as for the case where
+% the delimiters are different but there cannot be any nesting.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D_alt:w #1 \q_@@ #2#3
+ { #2 { \@@_expandable_grab_D_alt:NNwNNn #1 \q_@@ #2 #3 } }
+\cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new:Npn \@@_expandable_grab_D_alt:NNwNNn ##1##2##3 \q_@@ ##4##5##6
+ {
+ \str_if_eq:nnTF {##6} {##2}
+ {
+ \str_if_eq:onTF
+ { ##1 { } ##6 ##2 ##2 }
+ { { } ##2 }
+ }
+ { \use_ii:nn }
+ {
+ ##1
+ { \@@_expandable_grab_D_alt:NNwn ##4 ##5 ##3 \q_@@ }
+ ##6 \ERROR
+ }
+ { ##3 {#1} \q_@@ ##4 ##5 {##6} }
+ }
+ }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+\cs_new:Npn \@@_expandable_grab_D_alt:NNwn #1#2#3 \q_@@ #4
+ {
+ \tl_if_blank:oTF { \use_none:n #4 }
+ { \@@_put_arg_expandable:ow { \use_none:n #4 } }
+ {
+ \str_if_eq:eeTF
+ { \exp_not:o { \use_none:n #4 } }
+ { { \exp_not:o { \use_ii:nnn #4 \q_nil } } }
+ { \@@_put_arg_expandable:ow { \use_ii:nn #4 } }
+ { \@@_put_arg_expandable:ow { \use_none:n #4 } }
+ }
+ #3 \q_@@ #1 #2
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_E:w, \@@_expandable_grab_E_long:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_aux:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_test:nnw}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_loop:nnnNNw}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_find:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_find:nnw}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_end:nnw}
+% We keep track of long/short by placing the appropriate grabber as
+% the third token after \cs{q_@@}; it is eventually removed by the
+% \texttt{end:nnw} auxiliary. The \texttt{aux:w} auxiliary will be
+% called repeatedly with two arguments: the set
+% of pairs \meta{parser} \meta{token}, and the set of arguments found
+% so far (initially all |{-NoValue-}|). At each step, grab what
+% follows in the input stream then call the \texttt{loop:nnnNNw}
+% auxiliary to compare it with each possible embellishment in turn.
+% This auxiliary's |#1| is what was found in the input, |#2| collects
+% \meta{parser} \meta{token} pairs that did not match, |#3| collects
+% the corresponding arguments found previously, |#4| and |#5| is the
+% current pair, |#6| is the remaining pairs, |#7| is empty or two
+% \cs{q_nil}, and |#8| is the current argument. If none of the pairs
+% matched (determined by \cs{quark_if_nil:NTF}) then call the
+% \texttt{end} auxiliary to stop looking for embellishments,
+% remembering to put what was grabbed in the input back where it
+% belongs, and storing the arguments found just before \cs{q_@@}. If
+% the current argument |#8| is not |-NoValue-| or if the input |#1|
+% does not match |#5| (see \texttt{t}-type arguments below for a
+% similar \cs{str_if_eq:onTF} test) then carry on the loop.
+% Otherwise, we found a new embellishment: grab the corresponding
+% argument in the input using the \texttt{find:w} auxiliary. To avoid
+% losing braces around that auxiliary's argument we include a
+% space, which will be eliminated in the next loop through
+% embellishments.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_E:w #1 \q_@@ #2#3
+ { \@@_expandable_grab_E_aux:w #1 \q_@@ #2 #3 #3 }
+\cs_new:Npn \@@_expandable_grab_E_long:w #1 \q_@@ #2#3
+ { \@@_expandable_grab_E_aux:w #1 \q_@@ #2 #3 #2 }
+\cs_new:Npn \@@_expandable_grab_E_aux:w #1 \q_@@ #2#3#4
+ { #2 { \@@_expandable_grab_E_test:nnw #1 \q_@@ #2 #3 #4 } }
+\cs_new:Npn \@@_expandable_grab_E_test:nnw #1#2#3 \q_@@ #4#5#6#7
+ {
+ \@@_expandable_grab_E_loop:nnnNNw {#7} { } { }
+ #1 \q_nil \q_nil \q_nil \q_mark #2 \q_nil
+ #3 \q_@@ #4 #5 #6
+ }
+\cs_new:Npn \@@_expandable_grab_E_loop:nnnNNw
+ #1#2#3#4#5#6 \q_nil #7 \q_mark #8
+ {
+ \quark_if_nil:NTF #4
+ { \@@_expandable_grab_E_end:nnw {#1} {#3} }
+ {
+ \tl_if_novalue:nTF {#8}
+ { \str_if_eq:onTF { #4 { } #1 #5 } {#5} }
+ { \use_ii:nn }
+ { \@@_expandable_grab_E_find:w { #2 #4 #5 #6 } {#3} ~ }
+ {
+ \@@_expandable_grab_E_loop:nnnNNw
+ {#1} { #2 #4 #5 } { #3 {#8} }
+ #6 \q_nil #7 \q_mark
+ }
+ }
+ }
+\cs_new:Npn \@@_expandable_grab_E_find:w #1 \q_@@ #2#3#4
+ { #4 { \@@_expandable_grab_E_find:nnw #1 \q_@@ #2 #3 #4 } }
+\cs_new:Npn \@@_expandable_grab_E_find:nnw #1#2#3 \q_nil #4 \q_@@ #5#6#7#8
+ { \@@_expandable_grab_E_aux:w {#1} { #2 {#8} #3 } #4 \q_@@ #5 #6 #7 }
+\cs_new:Npn \@@_expandable_grab_E_end:nnw #1#2#3 \q_@@ #4#5#6
+ { #3 #2 \q_@@ #4 #5 {#1} }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_m:w, \@@_expandable_grab_m_long:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_m_aux:wNn}
+% The mandatory case is easy: find the auxiliary after the \cs{q_@@},
+% and use it directly to grab the argument, then correctly position
+% the argument before \cs{q_@@}.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_m:w #1 \q_@@ #2#3
+ { #3 { \@@_expandable_grab_m_aux:wNn #1 \q_@@ #2 #3 } }
+\cs_new:Npn \@@_expandable_grab_m_long:w #1 \q_@@ #2#3
+ { #2 { \@@_expandable_grab_m_aux:wNn #1 \q_@@ #2 #3 } }
+\cs_new:Npn \@@_expandable_grab_m_aux:wNn #1 \q_@@ #2#3#4
+ { #1 {#4} \q_@@ #2 #3 }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_R:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_R_aux:NNNwNNn}
+% Much the same as for the \texttt{D}-type argument, with only the lead-off
+% function varying.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_R:w #1 \q_@@ #2#3
+ { #2 { \@@_expandable_grab_R_aux:NNNwNNn #1 \q_@@ #2#3 } }
+\cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new:Npn \@@_expandable_grab_R_aux:NNNwNNn ##1##2##3##4 \q_@@ ##5##6##7
+ {
+ \str_if_eq:nnTF {##7} {##2}
+ {
+ \str_if_eq:onTF
+ { ##1 { } { } ##7 ##2 \q_@@ ##3 }
+ { { } {##2} { } }
+ }
+ { \use_ii:nn }
+ {
+ ##1
+ { \@@_expandable_grab_D:NNNwNNnnn ##1##2##3##4 \q_@@ ##5##6 }
+ \q_nil { } ##2 \ERROR \q_@@ \ERROR
+ }
+ {
+ \msg_expandable_error:nnff { cmd } { missing-required }
+ { \exp_args:Nf \tl_trim_spaces:n { \token_to_str:N ##5 } }
+ { \tl_to_str:n {##2} }
+ ##4 {#1} \q_@@ ##5 ##6 {##7}
+ }
+ }
+ }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_R_alt:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_R_alt_aux:NNwNNn}
+% When the delimiters are identical, nesting is not possible and a simplified
+% approach is used. The test concept here is the same as for the case where
+% the delimiters are different.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_R_alt:w #1 \q_@@ #2#3
+ { #2 { \@@_expandable_grab_R_alt_aux:NNwNNn #1 \q_@@ #2#3 } }
+\cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new:Npn \@@_expandable_grab_R_alt_aux:NNwNNn ##1##2##3 \q_@@ ##4##5##6
+ {
+ \str_if_eq:nnTF {##6} {##2}
+ {
+ \str_if_eq:onTF
+ { ##1 { } ##6 ##2 ##2 }
+ { { } ##2 }
+ }
+ { \use_ii:nn }
+ {
+ ##1
+ { \@@_expandable_grab_D_alt:NNwn ##4 ##5 ##3 \q_@@ }
+ ##6 \ERROR
+ }
+ {
+ \msg_expandable_error:nnff { cmd } { missing-required }
+ { \exp_args:Nf \tl_trim_spaces:n { \token_to_str:N ##4 } }
+ { \tl_to_str:n {##2} }
+ ##3 {#1} \q_@@ ##4 ##5 {##6}
+ }
+ }
+ }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_t:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_t_aux:NNwn}
+% As for a \texttt{D}-type argument, here we compare the grabbed tokens using
+% the only parser we have in order to work out if |#2| is exactly equal to
+% the output of the grabber.
+% \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_t:w #1 \q_@@ #2#3
+ { #2 { \@@_expandable_grab_t_aux:NNwn #1 \q_@@ #2 #3 } }
+\cs_new:Npn \@@_expandable_grab_t_aux:NNwn #1#2#3 \q_@@ #4#5#6
+ {
+ \str_if_eq:onTF { #1 { } #6 #2 } {#2}
+ { #3 { \BooleanTrue } \q_@@ #4 #5 }
+ { #3 { \BooleanFalse } \q_@@ #4 #5 {#6} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]
+% {\@@_put_arg_expandable:nw, \@@_put_arg_expandable:ow}
+% A useful helper, to store arguments when they are ready.
+% \begin{macrocode}
+\cs_new:Npn \@@_put_arg_expandable:nw #1#2 \q_@@ { #2 {#1} \q_@@ }
+\cs_generate_variant:Nn \@@_put_arg_expandable:nw { o }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Argument processors}
+%
+% \begin{macro}{\@@_bool_reverse:N}
+% A simple reversal.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_bool_reverse:N #1
+ {
+ \bool_if:NTF #1
+ { \tl_set:Nn \ProcessedArgument { \c_false_bool } }
+ { \tl_set:Nn \ProcessedArgument { \c_true_bool } }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{variable}{\l_@@_split_list_seq, \l_@@_split_list_tl}
+% \begin{macro}{\@@_split_list:nn}
+% \begin{macro}{\@@_split_list_multi:nn, \@@_split_list_multi:nV}
+% \begin{macro}{\@@_split_list_single:Nn}
+% Splitting can take place either at a single token or at a longer
+% identifier. To deal with single active tokens, a two-part procedure is
+% needed.
+% \begin{macrocode}
+\seq_new:N \l_@@_split_list_seq
+\tl_new:N \l_@@_split_list_tl
+\cs_new_protected:Npn \@@_split_list:nn #1#2
+ {
+ \tl_if_single:nTF {#1}
+ {
+ \token_if_cs:NTF #1
+ { \@@_split_list_multi:nn {#1} {#2} }
+ { \@@_split_list_single:Nn #1 {#2} }
+ }
+ { \@@_split_list_multi:nn {#1} {#2} }
+ }
+\cs_new_protected:Npn \@@_split_list_multi:nn #1#2
+ {
+ \seq_set_split:Nnn \l_@@_split_list_seq {#1} {#2}
+ \tl_clear:N \ProcessedArgument
+ \seq_map_inline:Nn \l_@@_split_list_seq
+ { \tl_put_right:Nn \ProcessedArgument { {##1} } }
+ }
+\cs_generate_variant:Nn \@@_split_list_multi:nn { nV }
+\group_begin:
+\char_set_catcode_active:N \^^@
+\cs_new_protected:Npn \@@_split_list_single:Nn #1#2
+ {
+ \tl_set:Nn \l_@@_split_list_tl {#2}
+ \group_begin:
+ \char_set_lccode:nn { `\^^@ } { `#1 }
+ \tex_lowercase:D
+ {
+ \group_end:
+ \tl_replace_all:Nnn \l_@@_split_list_tl { ^^@ }
+ } {#1}
+ \@@_split_list_multi:nV {#1} \l_@@_split_list_tl
+ }
+\group_end:
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{variable}
+%
+% \begin{macro}{\@@_split_argument:nnn}
+% \begin{macro}{\@@_split_argument_aux:nnnn}
+% \begin{macro}[EXP]{\@@_split_argument_aux:n}
+% \begin{macro}[rEXP]{\@@_split_argument_aux:wn}
+% Splitting to a known number of items is a special version of splitting
+% a list, in which the limit is hard-coded and where there will always be
+% exactly the correct number of output items. An auxiliary function is
+% used to save on working out the token list length several times.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_split_argument:nnn #1#2#3
+ {
+ \@@_split_list:nn {#2} {#3}
+ \exp_args:Nf \@@_split_argument_aux:nnnn
+ { \tl_count:N \ProcessedArgument }
+ {#1} {#2} {#3}
+ }
+\cs_new_protected:Npn \@@_split_argument_aux:nnnn #1#2#3#4
+ {
+ \int_compare:nNnF {#1} = { #2 + 1 }
+ {
+ \int_compare:nNnTF {#1} > { #2 + 1 }
+ {
+ \tl_set:Nx \ProcessedArgument
+ {
+ \exp_last_unbraced:NnNo
+ \@@_split_argument_aux:n
+ { #2 + 1 }
+ \use_none_delimit_by_q_stop:w
+ \ProcessedArgument
+ \q_stop
+ }
+ \msg_error:nnxxx { cmd } { split-excess-tokens }
+ { \tl_to_str:n {#3} } { \int_eval:n { #2 + 1 } }
+ { \tl_to_str:n {#4} }
+ }
+ {
+ \tl_put_right:Nx \ProcessedArgument
+ {
+ \prg_replicate:nn { #2 + 1 - (#1) }
+ { { \exp_not:V \c_novalue_tl } }
+ }
+ }
+ }
+ }
+% \end{macrocode}
+% Auxiliaries to leave exactly the correct number of arguments in
+% \cs{ProcessedArgument}.
+% \begin{macrocode}
+\cs_new:Npn \@@_split_argument_aux:n #1
+ { \prg_replicate:nn {#1} { \@@_split_argument_aux:wn } }
+\cs_new:Npn \@@_split_argument_aux:wn #1 \use_none_delimit_by_q_stop:w #2
+ {
+ \exp_not:n { {#2} }
+ #1
+ \use_none_delimit_by_q_stop:w
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_trim_spaces:n}
+% This one is almost trivial.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_trim_spaces:n #1
+ { \tl_set:Nx \ProcessedArgument { \tl_trim_spaces:n {#1} } }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Access to the argument specification}
+%
+% \begin{macro}{\@@_get_arg_spec_error:N, \@@_get_arg_spec_error:n}
+% \begin{macro}{\@@_get_arg_spec_error_aux:n}
+% Provide an informative error when trying to get the argument
+% specification of a non-\pkg{xparse} command or environment.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_get_arg_spec_error:N #1
+ {
+ \bool_set_false:N \l_@@_environment_bool
+ \tl_set:Nn \l_@@_fn_tl {#1}
+ \@@_get_arg_spec_error_aux:n { \cs_if_exist:NTF #1 }
+ }
+\cs_new_protected:Npn \@@_get_arg_spec_error:n #1
+ {
+ \bool_set_true:N \l_@@_environment_bool
+ \str_set:Nx \l_@@_environment_str {#1}
+ \@@_get_arg_spec_error_aux:n
+ { \cs_if_exist:cTF { \l_@@_environment_str } }
+ }
+\cs_new_protected:Npn \@@_get_arg_spec_error_aux:n #1
+ {
+ #1
+ {
+ \msg_error:nnx { cmd } { non-xparse }
+ { \@@_environment_or_command: }
+ }
+ {
+ \msg_error:nnx { cmd } { unknown }
+ { \@@_environment_or_command: }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_get_arg_spec:NTF}
+% If the command is not an \pkg{xparse} command, complain. If it is,
+% its second \enquote{item} is the argument specification.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_get_arg_spec:NTF #1#2#3
+ {
+ \__kernel_cmd_if_xparse:NTF #1
+ {
+ \tl_set:Nx \ArgumentSpecification { \tl_item:Nn #1 { 2 } }
+ #2
+ }
+ {#3}
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% Rolling forward from 2020-10-01 is tricky because the entire |ltcmd|
+% module is new, but the user-level commands have the same name, so only
+% these will clash. To work around that, in |latexrelease| mode we will
+% (temporarily) disable \cs{__kernel_chk_if_free_cs:N} for this final
+% part of the code, then restore at the end.
+% \begin{macrocode}
+%<latexrelease>\cs_new_eq:NN \@@_chk_if_free_cs:N \__kernel_chk_if_free_cs:N
+%<latexrelease>\cs_gset_eq:NN \__kernel_chk_if_free_cs:N \use_none:n
+% \end{macrocode}
+%
+% \begin{variable}{\ArgumentSpecification}
+% \begin{macrocode}
+\tl_new:N \ArgumentSpecification
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_get_arg_spec:N}
+% \begin{macro}{\@@_get_arg_spec:n}
+% Recovering the argument specification is now trivial.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_get_arg_spec:N #1
+ {
+ \@@_get_arg_spec:NTF #1 { }
+ { \@@_get_arg_spec_error:N #1 }
+ }
+\cs_new_protected:Npn \@@_get_arg_spec:n #1
+ {
+ \exp_args:Nc \@@_get_arg_spec:NTF
+ { environment~ \tl_to_str:n {#1} }
+ { }
+ { \@@_get_arg_spec_error:n {#1} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_show_arg_spec:N}
+% \begin{macro}{\@@_show_arg_spec:n}
+% Showing the argument specification simply means finding it and then
+% calling the \cs{tl_show:N} function.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_show_arg_spec:N #1
+ {
+ \@@_get_arg_spec:NTF #1
+ { \tl_show:N \ArgumentSpecification }
+ { \@@_get_arg_spec_error:N #1 }
+ }
+\cs_new_protected:Npn \@@_show_arg_spec:n #1
+ {
+ \exp_args:Nc \@@_get_arg_spec:NTF
+ { environment~ \tl_to_str:n {#1} }
+ { \tl_show:N \ArgumentSpecification }
+ { \@@_get_arg_spec_error:n {#1} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Utilities}
+%
+% \begin{macro}{\@@_check_definable:nNT, \@@_check_definable_aux:nN}
+% Check that a token list is appropriate as a first argument of
+% \cs{NewDocumentCommand} and similar functions and otherwise
+% produce an error. First trim whitespace to allow for spaces around
+% the actual command to be defined. If the result has multiple
+% tokens, it is not a valid argument. The single token is a control
+% sequence exactly if its string representation has more than one
+% character (using \cs{token_to_str:N} rather than \cs{tl_to_str:n}
+% to avoid problems with macro parameter characters, and setting
+% \cs{tex_escapechar:D} to prevent it from being non-printable).
+% Finally, check for an active character: this is done by lowercasing
+% the token to fix its character code (arbitrarily to that of~|?|)
+% and comparing the result to an active~|?|. Both control sequences
+% and active characters are valid arguments, and non-active character
+% tokens are not. In all cases, the group opened to keep assignments
+% local must be closed.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_check_definable:nNT #1
+ { \tl_trim_spaces_apply:nN {#1} \@@_check_definable_aux:nN }
+\group_begin:
+ \char_set_catcode_active:n { `? }
+ \cs_new_protected:Npn \@@_check_definable_aux:nN #1#2
+ {
+ \group_begin:
+ \tl_if_single_token:nTF {#1}
+ {
+ \int_set:Nn \tex_escapechar:D { 92 }
+ \exp_args:Nx \tl_if_empty:nTF
+ { \exp_args:No \str_tail:n { \token_to_str:N #1 } }
+ {
+ \exp_args:Nx \char_set_lccode:nn
+ { ` \str_head:n {#1} } { `? }
+ \tex_lowercase:D { \tl_if_eq:nnTF {#1} } { ? }
+ { \group_end: \use_iii:nnn }
+ { \group_end: \use_i:nnn }
+ }
+ { \group_end: \use_iii:nnn }
+ }
+ { \group_end: \use_ii:nnn }
+ {
+ \msg_error:nnxx { cmd } { not-definable }
+ { \tl_to_str:n {#1} } { \token_to_str:N #2 }
+ }
+ {
+ \msg_error:nnxx { cmd } { not-one-token }
+ { \tl_to_str:n {#1} } { \token_to_str:N #2 }
+ }
+ }
+\group_end:
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_token_if_cs:NTF}
+% Based on the definition of \cs{@@_check_definable_aux:nN} above, but
+% only checks for an actual control sequence (\emph{i.e.},
+% \cs[no-index]{\meta{anything}}). \cs{tex_escapechar:D} is
+% temporarily changed to a known value and then it checks if
+% |\string#1| contains more than one character: if it does, it's a
+% control sequence. This test differs from \cs{token_if_cs:NTF} for
+% example in \verb|\token_if_cs:NTF \c_group_begin_token {T}{F}|,
+% where \cs{token_if_cs:NTF} returns false.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_token_if_cs:NTF #1
+ {
+ \group_begin:
+ \int_set:Nn \tex_escapechar:D { 92 }
+ \exp_args:Nx \tl_if_empty:nTF
+ { \exp_args:No \str_tail:n { \token_to_str:N #1 } }
+ { \group_end: \use_ii:nn }
+ { \group_end: \use_i:nn }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_tl_mapthread_function:NNN, \@@_tl_mapthread_function:nnN}
+% \begin{macro}{\@@_tl_mapthread_loop:w}
+% Analogue of \cs{seq_mapthread_function:NNN} for token lists.
+% \begin{macrocode}
+\cs_new:Npn \@@_tl_mapthread_function:NNN #1#2#3
+ {
+ \exp_after:wN \exp_after:wN
+ \exp_after:wN \@@_tl_mapthread_loop:w
+ \exp_after:wN \exp_after:wN
+ \exp_after:wN #3
+ \exp_after:wN #1
+ \exp_after:wN \q_recursion_tail
+ \exp_after:wN \q_mark
+ #2
+ \q_recursion_tail
+ \q_recursion_stop
+ }
+\cs_new:Npn \@@_tl_mapthread_function:nnN #1#2#3
+ {
+ \@@_tl_mapthread_loop:w #3
+ #1 \q_recursion_tail \q_mark
+ #2 \q_recursion_tail \q_recursion_stop
+ }
+\cs_new:Npn \@@_tl_mapthread_loop:w #1#2#3 \q_mark #4
+ {
+ \quark_if_recursion_tail_stop:n {#2}
+ \quark_if_recursion_tail_stop:n {#4}
+ #1 {#2} {#4}
+ \@@_tl_mapthread_loop:w #1#3 \q_mark
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\__kernel_cmd_if_xparse:NTF}
+% \changes{v1.0d}{2021/04/19}{Renamed \cs{__cmd_cmd_if_xparse:NTF} to
+% \cs{__kernel_cmd_if_xparse:NTF} for cross-module usage}
+% \begin{macro}{\@@_cmd_if_xparse_aux:N}
+%
+% To determine whether the command is an \pkg{xparse} command check
+% that its |arg_spec| is empty (this also excludes non-macros) and
+% that its |replacement_spec| starts with either
+% \cs{@@_start:nNNnnn} (non-expandable command) or
+% \cs{@@_start_expandable:nNNNNn} (expandable command) or
+% \cs{@@_start_env:nnnnn} (environment).
+%
+% This conditional is needed in several kernel modules and is
+% therefore has a kernel-internal name.
+% \begin{macrocode}
+\cs_new_protected:Npn \__kernel_cmd_if_xparse:NTF #1
+ {
+ \exp_args:Nf \str_case_e:nnTF
+ {
+ \exp_args:Nf \tl_if_empty:nT { \cs_argument_spec:N #1 }
+ {
+ \exp_last_unbraced:Nf \@@_cmd_if_xparse_aux:w
+ { \cs_replacement_spec:N #1 } ~ \q_stop
+ }
+ }
+ {
+ { \token_to_str:N \@@_start:nNNnnn } { }
+ { \token_to_str:N \@@_start_expandable:nNNNNn } { }
+ { \token_to_str:N \@@_start_env:nnnnn } { }
+ }
+ }
+\cs_new:Npn \@@_cmd_if_xparse_aux:w #1 ~ #2 \q_stop {#1}
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_peek_nonspace:NTF, \@@_peek_nonspace_remove:NTF, \@@_peek_nonspace_aux:nNNTF}
+% Collect spaces in a loop, and put the collected spaces back in the
+% false branch of a call to \cs{peek_meaning:NTF} or
+% \cs{peek_meaning_remove:NTF}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_peek_nonspace:NTF
+ { \@@_peek_nonspace_aux:nNNTF { } \@@_peek_meaning:NTF }
+\cs_new_protected:Npn \@@_peek_nonspace_remove:NTF
+ { \@@_peek_nonspace_aux:nNNTF { } \@@_peek_meaning_remove:NTF }
+\cs_new_protected:Npn \@@_peek_nonspace_aux:nNNTF #1#2#3#4#5
+ {
+ \peek_meaning_remove:NTF \c_space_token
+ { \@@_peek_nonspace_aux:nNNTF { #1 ~ } #2 #3 {#4} {#5} }
+ { #2 #3 { #4 } { #5 #1 } }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_peek_meaning:NTF, \@@_peek_meaning_remove:NTF}
+% \begin{macro}{\@@_peek_cs_check_equal:NNN, \@@_peek_meaning_aux:NNTF, \@@_peek_true_remove:NNw}
+% Peek ahead for a token with a given meaning. In case the search
+% token is a control sequence, also check that the \meta{csname} is
+% the same as the control sequence peeked at. This extra verification
+% is necessary when the command is delimited by control sequence tokens
+% (as opposed to character tokens), and we want the the exact same
+% control sequence to match.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_peek_meaning:NTF
+ { \@@_peek_meaning_aux:NNTF \c_false_bool }
+\cs_new_protected:Npn \@@_peek_meaning_remove:NTF
+ { \@@_peek_meaning_aux:NNTF \c_true_bool }
+\cs_new_protected:Npn \@@_peek_meaning_aux:NNTF #1#2#3#4
+ {
+ \tl_set:Nn \l_@@_tmpa_tl {#3}
+ \tl_set:Nn \l_@@_tmpb_tl {#4}
+ \peek_meaning:NTF #2
+ {
+ \token_if_eq_meaning:NNTF #2 \c_group_begin_token
+ { \@@_peek_true_remove:Nw #1 }
+ {
+ \@@_token_if_cs:NTF #2
+ { \@@_peek_cs_check_equal:NNN #1 #2 }
+ { \@@_peek_true_remove:Nw #1 }
+ }
+ }
+ { \l_@@_tmpb_tl }
+ }
+\cs_new_protected:Npn \@@_peek_cs_check_equal:NNN #1#2#3
+ {
+ \str_if_eq:nnTF {#2} {#3}
+ { \@@_peek_true_remove:Nw #1 }
+ { \l_@@_tmpb_tl }
+ #3
+ }
+\cs_new_protected:Npn \@@_peek_true_remove:Nw #1
+ {
+ \bool_if:NTF #1
+ {
+ \tex_afterassignment:D \l_@@_tmpa_tl
+ \cs_set_eq:NN \@@_tmp:w
+ }
+ { \l_@@_tmpa_tl }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Messages}
+%
+% \begin{variable}{\c_@@_ignore_def_tl}
+% \begin{macrocode}
+\tl_const:Nn \c_@@_ignore_def_tl
+ { \\ \\ LaTeX~will~ignore~this~entire~definition. }
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_environment_or_command:}
+% Two texts used in several messages.
+% \begin{macrocode}
+\cs_new:Npn \@@_environment_or_command:
+ {
+ \bool_if:NTF \l_@@_environment_bool
+ { environment ~ ' \l_@@_environment_str ' }
+ {
+ command ~ '
+ \exp_args:Nf \tl_trim_spaces:n
+ { \exp_after:wN \token_to_str:N \l_@@_fn_tl }
+ '
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% Some messages intended as errors when defining commands/environments.
+% \begin{macrocode}
+\msg_new:nnnn { cmd } { arg-after-body }
+ { In~the~definition~of~#1,~b~(body)~argument~must~be~last. }
+ {
+ The~'body'~argument~type~is~followed~by~'#2'~in~the~argument~
+ specification~of~the~#1.~This~is~not~allowed.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { bad-arg-spec }
+ { Bad~argument~specification~'#2'~for~#1. }
+ {
+ The~argument~specification~provided~was~not~valid:~
+ one~or~more~mandatory~pieces~of~information~were~missing.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { command-already-defined }
+ { Command~'#1'~already~defined! }
+ {
+ You~have~used~#2~
+ with~a~command~that~already~has~a~definition. \\ \\
+ The~existing~definition~of~'#1'~will~not~be~altered.
+ }
+\msg_new:nnnn { cmd } { command-not-yet-defined }
+ { Command ~'#1'~not~yet~defined! }
+ {
+ You~have~used~#2~
+ with~a~command~that~was~never~defined.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { environment-already-defined }
+ { Environment~'#1'~already~defined! }
+ {
+ You~have~used~\NewDocumentEnvironment
+ with~an~environment~that~already~has~a~definition. \\ \\
+ The~existing~definition~of~'#1'~will~not~be~altered.
+ }
+\msg_new:nnnn { cmd } { environment-not-yet-defined }
+ { Environment~'#1'~not~yet~defined! }
+ {
+ You~have~used~\RenewDocumentEnvironment
+ with~an~environment~that~was~never~defined.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { expandable-ending-optional }
+ {
+ Argument~specification~'#2'~for~expandable~command~'#1'~
+ ends~with~optional~argument.
+ }
+ {
+ Expandable~commands~must~have~a~final~mandatory~argument~
+ (or~no~arguments~at~all).~You~cannot~have~a~terminal~optional~
+ argument~with~expandable~commands.
+ }
+\msg_new:nnnn { cmd } { inconsistent-long }
+ { Inconsistent~long~arguments~for~expandable~command~'#1'. }
+ {
+ The~arguments~for~an~expandable~command~must~not~involve~short~
+ arguments~after~long~arguments.~You~have~tried~to~mix~the~two~types.
+ }
+\msg_new:nnnn { cmd } { invalid-command-arg }
+ { Argument~type~'#2'~not~available~for~#1. }
+ {
+ The~letter~'#2'~can~only~be~used~in~environment~argument~
+ specifications,~not~for~commands.
+ \\ \\
+ LaTeX~will~ignore~this~entire~definition.
+ }
+\msg_new:nnnn { cmd } { invalid-expandable-argument-type }
+ { Argument~type~'#2'~not~available~for~expandable~command~'#1'. }
+ {
+ The~letter~'#2'~specifies~an~argument~type~which~cannot~be~used~
+ in~an~expandable~command.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { invalid-after-optional-expandably }
+ {
+ Argument~type~'#2'~not~available~after~optional~argument~
+ for~expandable~command~'#1'.
+ }
+ {
+ The~letter~'#2'~specifies~an~argument~type~which~cannot~be~used~
+ in~an~expandable~command~after~an~optional~argument.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { non-trailing-obey-spaces }
+ { Prefix~'!'~used~before~mandatory~argument~'#2'~of~#1. }
+ {
+ The~prefix~'!'~can~only~apply~to~trailing~optional~arguments.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { not-definable }
+ { First~argument~of~'#2'~must~be~a~command. }
+ {
+ The~first~argument~of~'#2'~should~be~the~document~command~that~will~
+ be~defined.~The~provided~argument~'#1'~is~a~character.~Perhaps~a~
+ backslash~is~missing?
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { not-one-token }
+ { First~argument~of~'#2'~must~be~a~command. }
+ {
+ The~first~argument~of~'#2'~should~be~the~document~command~that~will~
+ be~defined.~The~provided~argument~'#1'~contains~more~than~one~
+ token.~Perhaps~a~backslash~is~missing?
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { not-single-token }
+ {
+ Argument~delimiter~'#2'~for~the~#1~should~be~
+ a~single~non-space~token.
+ }
+ {
+ The~argument~specification~provided~was~not~valid:~in~a~place~
+ where~a~single~token~is~required,~LaTeX~found~'#2'.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { forbidden-implicit-group-token }
+ { Argument~delimiter~'#2'~for~the~#1~is~not~allowed. }
+ {
+ The~argument~specification~provided~was~not~valid:~the~implicit~
+ #3-group~token~'#2'~is~not~allowed~as~an~argument~delimiter.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { processor-in-expandable }
+ { Argument~processor~'>{#2}'~cannot~be~used~for~the~expandable~command~'#1'. }
+ {
+ The~argument~specification~for~#1~contains~a~processor~function:~
+ this~is~only~supported~for~standard~robust~commands.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { too-many-arguments }
+ { Too~many~arguments~in~argument~specification~'#2'~of~#1. }
+ {
+ The~argument~specification~provided~has~more~than~9~arguments.~
+ This~cannot~be~implemented.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { two-markers }
+ { Two~'#2'~apply~to~the~same~argument~in~argument~specification~of~#1. }
+ {
+ The~argument~specification~provided~has~two~markers~'#2'~applying~
+ to~the~same~argument;~these~are~redundant.
+ }
+\msg_new:nnnn { cmd } { unknown-argument-type }
+ { Unknown~argument~type~'#2'~for~the~#1. }
+ {
+ The~letter~'#2'~does~not~specify~a~known~argument~type.
+ \c_@@_ignore_def_tl
+ }
+\msg_new:nnnn { cmd } { xparse-argument-type }
+ { Deprecated~argument~type~'#2'~for~the~#1~requires~xparse. }
+ {
+ The~letter~'#2'~specifies~a~known~argument~type~that~requires~
+ the~xparse~package.
+ \c_@@_ignore_def_tl
+ }
+% \end{macrocode}
+%
+% Errors when using commands/environments. The \texttt{if-boolean}
+% message is always used in expandable errors. The
+% \texttt{loop-in-defaults} and \texttt{missing-required} messages can
+% be expandable or not expandable.
+% \begin{macrocode}
+\msg_new:nnn { cmd } { if-boolean }
+ { Invalid~use~\iow_char:N\\IfBooleanTF~{#1} }
+\msg_new:nnnn { cmd } { loop-in-defaults }
+ { Defaults~of~#1~have~circular~dependency. }
+ {
+ The~default~values~of~two~or~more~arguments~of~the~#1~
+ depend~on~each~other~in~a~way~that~cannot~be~resolved.
+ }
+\msg_new:nnnn { cmd } { missing-required }
+ { Missing~required~argument~for~#1. }
+ {
+ The~current~#1~expects~an~argument~starting~with~'#2'.~
+ LaTeX~did~not~find~it,~and~will~insert~a~default~value~to~be~processed.
+ }
+\msg_new:nnnn { cmd } { non-xparse }
+ { \str_uppercase:n #1~not~defined~using~xparse. }
+ {
+ You~have~asked~for~the~argument~specification~for~the~#1,~
+ but~this~was~not~defined~using~xparse.
+ }
+\msg_new:nnnn { cmd } { split-excess-tokens }
+ { Too~many~'#1'~tokens~when~trying~to~split~argument. }
+ {
+ LaTeX~was~asked~to~split~the~input~'#3'~
+ at~each~occurrence~of~the~token~'#1',~up~to~a~maximum~of~#2~parts.~
+ There~were~too~many~'#1'~tokens.
+ }
+\msg_new:nnnn { cmd } { unknown }
+ { Unknown~document~#1. }
+ {
+ You~have~asked~for~the~argument~specification~for~the~#1,~
+ but~it~is~not~defined.
+ }
+\msg_new:nnnn { cmd } { verbatim-newline }
+ { Verbatim~argument~of~#1~ended~by~end~of~line. }
+ {
+ The~verbatim~argument~of~the~#1~cannot~contain~more~than~one~line,~
+ but~the~end~
+ of~the~current~line~has~been~reached.~You~may~have~forgotten~the~
+ closing~delimiter.
+ \\ \\
+ LaTeX~will~ignore~'#2'.
+ }
+\msg_new:nnnn { cmd } { verbatim-tokenized }
+ { The~verbatim~#1~cannot~be~used~inside~an~argument. }
+ {
+ The~#1~takes~a~verbatim~argument.~
+ It~may~not~appear~within~the~argument~of~another~function.~
+ It~received~an~illegal~token \tl_if_empty:nF {#3} { ~'#3' } .
+ \\ \\
+ LaTeX~will~ignore~'#2'.
+ }
+% \end{macrocode}
+%
+% Intended more for information.
+% \begin{macrocode}
+\msg_new:nnn { cmd } { define-command }
+ {
+ Defining~command~#1~
+ with~sig.~'#2'~\msg_line_context:.
+ }
+\msg_new:nnn { cmd } { define-environment }
+ {
+ Defining~environment~'#1'~
+ with~sig.~'#2'~\msg_line_context:.
+ }
+\msg_new:nnn { cmd } { redefine-command }
+ {
+ Redefining~command~#1~
+ with~sig.~'#2'~\msg_line_context:.
+ }
+\msg_new:nnn { cmd } { redefine-environment }
+ {
+ Redefining~environment~'#1'~
+ with~sig.~'#2'~\msg_line_context:.
+ }
+\msg_new:nnn { cmd } { optional-mandatory }
+ {
+ Since~the~mandatory~argument~'#1'~has~the~same~delimiter~'#2'~
+ as~a~previous~optional~argument,~it~will~not~be~possible~to~
+ omit~all~optional~arguments~when~calling~this~command.
+ }
+\msg_new:nnn { cmd } { unsupported-let }
+ {
+ The~command~'#1'~was~undefined~but~not~the~associated~commands~
+ '#1~code'~and/or~'#1~defaults'.~Maybe~you~tried~using~
+ \iow_char:N\\let.~This~may~lead~to~an~infinite~loop.
+ }
+% \end{macrocode}
+%
+% \subsection{User functions}
+%
+% The user functions are more or less just the internal functions
+% renamed.
+%
+% \begin{macro}{\BooleanFalse}
+% \begin{macro}{\BooleanTrue}
+% Design-space names for the Boolean values.
+% \begin{macrocode}
+\cs_new_eq:NN \BooleanFalse \c_false_bool
+\cs_new_eq:NN \BooleanTrue \c_true_bool
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\NewDocumentCommand}
+% \begin{macro}{\RenewDocumentCommand}
+% \begin{macro}{\ProvideDocumentCommand}
+% \begin{macro}{\DeclareDocumentCommand}
+% The user macros are pretty simple wrappers around the internal ones.
+% There is however a check that the first argument is a single token,
+% possibly surrounded by spaces (hence the strange \cs{use:nnn}), and
+% is definable.
+% \begin{macrocode}
+\cs_new_protected:Npn \NewDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \NewDocumentCommand
+ {
+ \cs_if_exist:NTF #1
+ {
+ \msg_error:nnxx { cmd } { command-already-defined }
+ { \use:nnn \token_to_str:N #1 { } }
+ { \token_to_str:N \NewDocumentCommand }
+ }
+ { \@@_declare_cmd:Nnn #1 {#2} {#3} }
+ }
+ }
+\cs_new_protected:Npn \RenewDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \RenewDocumentCommand
+ {
+ \cs_if_exist:NTF #1
+ { \@@_declare_cmd:Nnn #1 {#2} {#3} }
+ {
+ \msg_error:nnxx { cmd } { command-not-yet-defined }
+ { \use:nnn \token_to_str:N #1 { } }
+ { \token_to_str:N \RenewDocumentCommand }
+ }
+ }
+ }
+\cs_new_protected:Npn \ProvideDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \ProvideDocumentCommand
+ { \cs_if_exist:NF #1 { \@@_declare_cmd:Nnn #1 {#2} {#3} } }
+ }
+\cs_new_protected:Npn \DeclareDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \DeclareDocumentCommand
+ { \@@_declare_cmd:Nnn #1 {#2} {#3} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\NewDocumentEnvironment}
+% \begin{macro}{\RenewDocumentEnvironment}
+% \begin{macro}{\ProvideDocumentEnvironment}
+% \begin{macro}{\DeclareDocumentEnvironment}
+% Very similar for environments.
+% \begin{macrocode}
+\cs_new_protected:Npn \NewDocumentEnvironment #1#2#3#4
+ {
+ \cs_if_exist:cTF {#1}
+ { \msg_error:nnx { cmd } { environment-already-defined } {#1} }
+ { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} }
+ }
+\cs_new_protected:Npn \RenewDocumentEnvironment #1#2#3#4
+ {
+ \cs_if_exist:cTF {#1}
+ { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} }
+ { \msg_error:nnx { cmd } { environment-not-yet-defined } {#1} }
+ }
+\cs_new_protected:Npn \ProvideDocumentEnvironment #1#2#3#4
+ { \cs_if_exist:cF {#1} { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} } }
+\cs_new_protected:Npn \DeclareDocumentEnvironment #1#2#3#4
+ { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\NewExpandableDocumentCommand}
+% \begin{macro}{\RenewExpandableDocumentCommand}
+% \begin{macro}{\ProvideExpandableDocumentCommand}
+% \begin{macro}{\DeclareExpandableDocumentCommand}
+% The expandable versions are essentially the same as the basic
+% functions. The strange \cs{use:nnn} is there in case |#1| is
+% surrounded with spaces, as can happen with usual document catcodes
+% in \cs{RenewExpandableDocumentCommand} |{| |\!| |}| \ldots{}
+% \begin{macrocode}
+\cs_new_protected:Npn \NewExpandableDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \NewExpandableDocumentCommand
+ {
+ \cs_if_exist:NTF #1
+ {
+ \msg_error:nnxx { cmd } { command-already-defined }
+ { \use:nnn \token_to_str:N #1 { } }
+ { \token_to_str:N \NewExpandableDocumentCommand }
+ }
+ { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+ }
+ }
+\cs_new_protected:Npn \RenewExpandableDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \RenewExpandableDocumentCommand
+ {
+ \cs_if_exist:NTF #1
+ { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+ {
+ \msg_error:nnxx { cmd } { command-not-yet-defined }
+ { \use:nnn \token_to_str:N #1 { } }
+ { \token_to_str:N \RenewExpandableDocumentCommand }
+ }
+ }
+ }
+\cs_new_protected:Npn \ProvideExpandableDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \ProvideExpandableDocumentCommand
+ {
+ \cs_if_exist:NF #1
+ { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+ }
+ }
+\cs_new_protected:Npn \DeclareExpandableDocumentCommand #1#2#3
+ {
+ \@@_check_definable:nNT {#1} \DeclareExpandableDocumentCommand
+ { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\IfBooleanT, \IfBooleanF, \IfBooleanTF}
+% The logical \meta{true} and \meta{false} statements are just the
+% normal \cs{c_true_bool} and \cs{c_false_bool} so \cs{bool_if:NTF} is
+% almost enough. However, this code-level function blows up badly
+% when passed invalid input. We want \cs{IfBooleanTF} to accept a
+% single (non-space) token equal to \cs{c_true_bool} or
+% \cs{c_false_bool}, possibly surrounded by spaces. If the input is
+% blank or multiple items, jump to the error and pick the false
+% branch. If the input, ignoring spaces (we do this by omitting
+% braces in the \cs{tl_if_single_token:nF} test), is not a single
+% token then jump to the error as well. It is then safe to compare
+% the token to the two booleans, picking the appropriate branch. If
+% neither matches, we jump to the error as well.
+% \begin{macrocode}
+\cs_new:Npn \IfBooleanTF #1
+ {
+ \tl_if_single:nF {#1}
+ { \prg_break:n { \use:n } }
+ \tl_if_single_token:nF #1
+ { \prg_break:n { \use:n } }
+ \token_if_eq_meaning:NNT #1 \c_true_bool
+ { \prg_break:n { \use_ii:nnn } }
+ \token_if_eq_meaning:NNT #1 \c_false_bool
+ { \prg_break:n { \use_iii:nnn } }
+ \prg_break:n { \use:n }
+ \prg_break_point:
+ {
+ \msg_expandable_error:nnn { cmd } { if-boolean } {#1}
+ \use_ii:nn
+ }
+ }
+\cs_new:Npn \IfBooleanT #1#2 { \IfBooleanTF {#1} {#2} { } }
+\cs_new:Npn \IfBooleanF #1 { \IfBooleanTF {#1} { } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\IfNoValueT, \IfNoValueF, \IfNoValueTF}
+% Simple re-naming.
+% \begin{macrocode}
+\cs_new_eq:NN \IfNoValueF \tl_if_novalue:nF
+\cs_new_eq:NN \IfNoValueT \tl_if_novalue:nT
+\cs_new_eq:NN \IfNoValueTF \tl_if_novalue:nTF
+% \end{macrocode}
+% \end{macro}
+% \begin{macro}{\IfValueT, \IfValueF, \IfValueTF}
+% Inverted logic.
+% \begin{macrocode}
+\cs_new:Npn \IfValueF { \tl_if_novalue:nT }
+\cs_new:Npn \IfValueT { \tl_if_novalue:nF }
+\cs_new:Npn \IfValueTF #1#2#3 { \tl_if_novalue:nTF {#1} {#3} {#2} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\ProcessedArgument}
+% Processed arguments are returned using this name, which is reserved
+% here although the definition will change.
+% \begin{macrocode}
+\tl_new:N \ProcessedArgument
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\ReverseBoolean, \SplitArgument, \SplitList, \TrimSpaces}
+% Simple copies.
+% \begin{macrocode}
+\cs_new_eq:NN \ReverseBoolean \@@_bool_reverse:N
+\cs_new_eq:NN \SplitArgument \@@_split_argument:nnn
+\cs_new_eq:NN \SplitList \@@_split_list:nn
+\cs_new_eq:NN \TrimSpaces \@@_trim_spaces:n
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\ProcessList}
+% To support \cs{SplitList}.
+% \begin{macrocode}
+\cs_new_eq:NN \ProcessList \tl_map_function:nN
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\GetDocumentCommandArgSpec}
+% \begin{macro}{\GetDocumentEnvironmentArgSpec}
+% \begin{macro}{\ShowDocumentCommandArgSpec}
+% \begin{macro}{\ShowDocumentEnvironmentArgSpec}
+% More simple mappings, with a check that the argument is a single
+% control sequence or active character.
+% \begin{macrocode}
+\cs_new_protected:Npn \GetDocumentCommandArgSpec #1
+ {
+ \@@_check_definable:nNT {#1} \GetDocumentCommandArgSpec
+ { \@@_get_arg_spec:N #1 }
+ }
+\cs_new_eq:NN \GetDocumentEnvironmentArgSpec \@@_get_arg_spec:n
+\cs_new_protected:Npn \ShowDocumentCommandArgSpec #1
+ {
+ \@@_check_definable:nNT {#1} \ShowDocumentCommandArgSpec
+ { \@@_show_arg_spec:N #1 }
+ }
+\cs_new_eq:NN \ShowDocumentEnvironmentArgSpec \@@_show_arg_spec:n
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% Finally as promised, restore \cs{__kernel_chk_if_free_cs:N}:
+% \begin{macrocode}
+%<latexrelease>\cs_gset_eq:NN \__kernel_chk_if_free_cs:N \@@_chk_if_free_cs:N
+%<latexrelease>\cs_undefine:N \@@_chk_if_free_cs:N
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<latexrelease>
+%<latexrelease>\IncludeInRelease{0000/00/00}{ltcmd}%
+%<latexrelease> {Document~command~parser}%
+%<latexrelease>
+%<latexrelease>\EndModuleRelease
+\ExplSyntaxOff
+%<latexrelease>\@ifundefined{ExplSyntaxOff}{}{\latexrelease@postexpl}
+%<latexrelease>\catcode`\^^@=\@latexrelease@catcode@null\relax
+%</2ekernel|latexrelease>
+% \end{macrocode}
+%
+% We need to stop DocStrip treating |@@| in a special way at this point.
+% \begin{macrocode}
+%<@@=>
+% \end{macrocode}
+%
+% \Finale