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+% \iffalse meta-comment
+%
+%% File: l3keys.dtx
+%
+% Copyright (C) 2006-2024 The LaTeX Project
+%
+% It may be distributed and/or modified under the conditions of the
+% LaTeX Project Public License (LPPL), either version 1.3c of this
+% license or (at your option) any later version. The latest version
+% of this license is in the file
+%
+% https://www.latex-project.org/lppl.txt
+%
+% This file is part of the "l3kernel bundle" (The Work in LPPL)
+% and all files in that bundle must be distributed together.
+%
+% -----------------------------------------------------------------------
+%
+% The development version of the bundle can be found at
+%
+% https://github.com/latex3/latex3
+%
+% for those people who are interested.
+%
+%<*driver>
+\documentclass[full,kernel]{l3doc}
+\begin{document}
+ \DocInput{\jobname.dtx}
+\end{document}
+%</driver>
+% \fi
+%
+% \title{^^A
+% The \pkg{l3keys} module\\ Key--value interfaces^^A
+% }
+%
+% \author{^^A
+% The \LaTeX{} Project\thanks
+% {^^A
+% E-mail:
+% \href{mailto:latex-team@latex-project.org}
+% {latex-team@latex-project.org}^^A
+% }^^A
+% }
+%
+% \date{Released 2024-04-11}
+%
+% \maketitle
+%
+% \begin{documentation}
+%
+% The key--value method is a popular system for creating large numbers
+% of settings for controlling function or package behaviour. The
+% system normally results in input of the form
+% \begin{verbatim}
+% \MyModuleSetup{
+% key-one = value one,
+% key-two = value two
+% }
+% \end{verbatim}
+% or
+% \begin{verbatim}
+% \MyModuleMacro[
+% key-one = value one,
+% key-two = value two
+% ]{argument}
+% \end{verbatim}
+% for the user.
+%
+% The high level functions here are intended as a method to create
+% key--value controls. Keys are themselves created using a key--value
+% interface, minimising the number of functions and arguments
+% required. Each key is created by setting one or more \emph{properties}
+% of the key:
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key-one .code:n = code including parameter #1,
+% key-two .tl_set:N = \l_mymodule_store_tl
+% }
+% \end{verbatim}
+% These values can then be set as with other key--value approaches:
+% \begin{verbatim}
+% \keys_set:nn { mymodule }
+% {
+% key-one = value one,
+% key-two = value two
+% }
+% \end{verbatim}
+% As illustrated, keys are created inside a \meta{module}: a set of related
+% keys, typically those for a single module/\LaTeXe{} package. See
+% Section~\ref{sec:l3keys:subdivision} for suggestions on how to divide
+% large numbers of keys for a single module.
+%
+% At a document level, \cs{keys_set:nn} is used within a
+% document function, for example
+% \begin{verbatim}
+% \DeclareDocumentCommand \MyModuleSetup { m }
+% { \keys_set:nn { mymodule } { #1 } }
+% \DeclareDocumentCommand \MyModuleMacro { o m }
+% {
+% \group_begin:
+% \keys_set:nn { mymodule } { #1 }
+% % Main code for \MyModuleMacro
+% \group_end:
+% }
+% \end{verbatim}
+%
+% Key names may contain any tokens, as they are handled internally
+% using \cs{tl_to_str:n}. As discussed in
+% section~\ref{sec:l3keys:subdivision}, it is suggested that the character
+% |/| is reserved for sub-division of keys into different subsets.
+% Functions and variables are \emph{not} expanded when creating
+% key names, and so
+% \begin{verbatim}
+% \tl_set:Nn \l_mymodule_tmp_tl { key }
+% \keys_define:nn { mymodule }
+% {
+% \l_mymodule_tmp_tl .code:n = code
+% }
+% \end{verbatim}
+% creates a key called |\l_mymodule_tmp_tl|, and not one called
+% \texttt{key}.
+%
+% \section{Creating keys}
+%
+% \begin{function}[updated = 2017-11-14]
+% {\keys_define:nn, \keys_define:ne}
+% \begin{syntax}
+% \cs{keys_define:nn} \Arg{module} \Arg{keyval list}
+% \end{syntax}
+% Parses the \meta{keyval list} and defines the keys listed there for
+% \meta{module}. The \meta{module} name is treated as a string.
+% In practice the
+% \meta{module} should be chosen to be unique to the module in question
+% (unless deliberately adding keys to an existing module).
+%
+% The \meta{keyval list} should consist of one or more key names along
+% with an associated key \emph{property}. The properties of a key
+% determine how it acts. The individual properties are described
+% in the following text; a typical use of \cs{keys_define:nn} might
+% read
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% keyname .code:n = Some~code~using~#1,
+% keyname .value_required:n = true
+% }
+% \end{verbatim}
+% where the properties of the key begin from the |.| after the key
+% name.
+% \end{function}
+%
+% The various properties available take either no arguments at
+% all, or require one or more arguments. This is indicated in the
+% name of the property using an argument specification. In the following
+% discussion, each property is illustrated attached to an
+% arbitrary \meta{key}, which when used may be supplied with a
+% \meta{value}. All key \emph{definitions} are local.
+%
+% Key properties are applied in the reading order and so the ordering
+% is significant. Key properties which define \enquote{actions}, such
+% as |.code:n|, |.tl_set:N|, \emph{etc.}, override one another.
+% Some other properties are mutually exclusive, notably |.value_required:n|
+% and |.value_forbidden:n|, and so they replace one another. However,
+% properties covering non-exclusive behaviours may be given in any order. Thus
+% for example the following definitions are equivalent.
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% keyname .code:n = Some~code~using~#1,
+% keyname .value_required:n = true
+% }
+% \keys_define:nn { mymodule }
+% {
+% keyname .value_required:n = true,
+% keyname .code:n = Some~code~using~#1
+% }
+% \end{verbatim}
+% Note that all key properties define the key within the current \TeX{} group,
+% with an exception that the special |.undefine:| property \emph{undefines} the
+% key within the current \TeX{} group.
+%
+% \begin{function}[updated = 2013-07-08]
+% {.bool_set:N, .bool_set:c, .bool_gset:N, .bool_gset:c}
+% \begin{syntax}
+% \meta{key} .bool_set:N = \meta{boolean variable}
+% \end{syntax}
+% Defines \meta{key} to set \meta{boolean variable} to \meta{value} (which
+% must be either \enquote{\texttt{true}} or \enquote{\texttt{false}}). If the variable
+% does not exist, it will be created globally at the point that
+% the key is set up.
+% \end{function}
+%
+% \begin{function}[added = 2011-08-28, updated = 2013-07-08]
+% {
+% .bool_set_inverse:N, .bool_set_inverse:c,
+% .bool_gset_inverse:N, .bool_gset_inverse:c
+% }
+% \begin{syntax}
+% \meta{key} .bool_set_inverse:N = \meta{boolean variable}
+% \end{syntax}
+% Defines \meta{key} to set \meta{boolean variable} to the logical
+% inverse of \meta{value} (which must be either \enquote{\texttt{true}} or
+% \enquote{\texttt{false}}).
+% If the \meta{boolean variable} does not exist, it will be created globally
+% at the point that the key is set up.
+% \end{function}
+%
+% \begin{function}{.choice:}
+% \begin{syntax}
+% \meta{key} .choice:
+% \end{syntax}
+% Sets \meta{key} to act as a choice key. Each valid choice
+% for \meta{key} must then be created, as discussed in
+% section~\ref{sec:l3keys:choice}.
+% \end{function}
+%
+% \begin{function}[added = 2011-08-21, updated = 2013-07-10]
+% {.choices:nn, .choices:Vn, .choices:en, .choices:on}
+% \begin{syntax}
+% \meta{key} .choices:nn = \Arg{choices} \Arg{code}
+% \end{syntax}
+% Sets \meta{key} to act as a choice key, and defines a series \meta{choices}
+% which are implemented using the \meta{code}. Inside \meta{code},
+% \cs{l_keys_choice_tl} will be the name of the choice made, and
+% \cs{l_keys_choice_int} will be the position of the choice in the list
+% of \meta{choices} (indexed from~$1$).
+% Choices are discussed in detail in section~\ref{sec:l3keys:choice}.
+% \end{function}
+%
+% \begin{function}[added = 2011-09-11]
+% {.clist_set:N, .clist_set:c, .clist_gset:N, .clist_gset:c}
+% \begin{syntax}
+% \meta{key} .clist_set:N = \meta{comma list variable}
+% \end{syntax}
+% Defines \meta{key} to set \meta{comma list variable} to \meta{value}.
+% Spaces around commas and empty items will be stripped.
+% If the variable does not exist, it
+% is created globally at the point that the key is set up.
+% \end{function}
+%
+% \begin{function}[updated = 2013-07-10]{.code:n}
+% \begin{syntax}
+% \meta{key} .code:n = \Arg{code}
+% \end{syntax}
+% Stores the \meta{code} for execution when \meta{key} is used.
+% The \meta{code} can include one parameter (|#1|), which will be the
+% \meta{value} given for the \meta{key}.
+% \end{function}
+%
+% \begin{function}[added = 2020-01-11]
+% {
+% .cs_set:Np, .cs_set:cp,
+% .cs_set_protected:Np, .cs_set_protected:cp,
+% .cs_gset:Np, .cs_gset:cp,
+% .cs_gset_protected:Np, .cs_gset_protected:cp,
+% }
+% \begin{syntax}
+% \meta{key} .cs_set:Np = \meta{control sequence} \meta{arg.~spec.}
+% \end{syntax}
+% Defines \meta{key} to set \meta{control sequence} to have \meta{arg.~spec.}
+% and replacement text \meta{value}.
+% \end{function}
+%
+% \begin{function}[updated = 2013-07-09]
+% {.default:n, .default:V, .default:e, .default:o}
+% \begin{syntax}
+% \meta{key} .default:n = \Arg{default}
+% \end{syntax}
+% Creates a \meta{default} value for \meta{key}, which is used if no
+% value is given. This will be used if only the key name is given,
+% but not if a blank \meta{value} is given:
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key .code:n = Hello~#1,
+% key .default:n = World
+% }
+% \keys_set:nn { mymodule }
+% {
+% key = Fred, % Prints 'Hello Fred'
+% key, % Prints 'Hello World'
+% key = , % Prints 'Hello '
+% }
+% \end{verbatim}
+% The default does not affect keys where values are required or
+% forbidden. Thus a required value cannot be supplied by a default
+% value, and giving a default value for a key which cannot take a value
+% does not trigger an error.
+%
+% When no value is given for a key as part of \cs{keys_set:nn}, the
+% \texttt{.default:n} value provides the value before key properties are
+% considered. The only exception is when the \texttt{.value_required:n}
+% property is active: a required value cannot be supplied by the default,
+% and must be explicitly given as part of \cs{keys_set:nn}.
+% \end{function}
+%
+% \begin{function}[updated = 2020-01-17]
+% {.dim_set:N, .dim_set:c, .dim_gset:N, .dim_gset:c}
+% \begin{syntax}
+% \meta{key} .dim_set:N = \meta{dimension}
+% \end{syntax}
+% Defines \meta{key} to set \meta{dimension} to \meta{value} (which
+% must a dimension expression). If the variable does not exist, it
+% is created globally at the point that the key is set up. The key will
+% require a value at point-of-use unless a default is set.
+% \end{function}
+%
+% \begin{function}[updated = 2020-01-17]
+% {.fp_set:N, .fp_set:c, .fp_gset:N, .fp_gset:c}
+% \begin{syntax}
+% \meta{key} .fp_set:N = \meta{floating point}
+% \end{syntax}
+% Defines \meta{key} to set \meta{floating point} to \meta{value}
+% (which must a floating point expression). If the variable does not exist,
+% it is created globally at the point that the key is set up. The key will
+% require a value at point-of-use unless a default is set.
+% \end{function}
+%
+% \begin{function}[added = 2013-07-14]
+% {.groups:n}
+% \begin{syntax}
+% \meta{key} .groups:n = \Arg{groups}
+% \end{syntax}
+% Defines \meta{key} as belonging to the \meta{groups} (a
+% comma-separated list). Groups
+% provide a \enquote{secondary axis} for selectively setting keys, and are
+% described in Section~\ref{sec:l3keys:selective}.
+% \begin{texnote}
+% The \meta{groups} argument is turned into a string then
+% interpreted as a comma-separated list, so group names cannot
+% contain commas nor start or end with a space character.
+% \end{texnote}
+% \end{function}
+%
+% \begin{function}[added = 2016-11-22]{.inherit:n}
+% \begin{syntax}
+% \meta{key} .inherit:n = \Arg{parents}
+% \end{syntax}
+% Specifies that the \meta{key} path should inherit the keys listed
+% as any of the \meta{parents} (a comma list), which can be a module
+% or a sub-division thereof. For example, after setting
+% \begin{verbatim}
+% \keys_define:nn { foo } { test .code:n = \tl_show:n {#1} }
+% \keys_define:nn { } { bar .inherit:n = foo }
+% \end{verbatim}
+% setting
+% \begin{verbatim}
+% \keys_set:nn { bar } { test = a }
+% \end{verbatim}
+% will be equivalent to
+% \begin{verbatim}
+% \keys_set:nn { foo } { test = a }
+% \end{verbatim}
+% Inheritance applies at point of use, not at definition, thus keys may
+% be added to the \meta{parent} after the use of \texttt{.inherit:n}
+% and will be active.
+% If more than one \meta{parent} is specified, the presence of the
+% \meta{key} will be tested for each in turn, with the first successful
+% hit taking priority.
+% \end{function}
+%
+% \begin{function}[updated = 2013-07-09]
+% {.initial:n, .initial:V, .initial:e, .initial:o}
+% \begin{syntax}
+% \meta{key} .initial:n = \Arg{value}
+% \end{syntax}
+% Initialises the \meta{key} with the \meta{value}, equivalent to
+% \begin{quote}
+% \cs{keys_set:nn} \Arg{module} \{ \meta{key} = \meta{value} \}
+% \end{quote}
+% \end{function}
+%
+% \begin{function}[updated = 2020-01-17]
+% {.int_set:N, .int_set:c, .int_gset:N, .int_gset:c}
+% \begin{syntax}
+% \meta{key} .int_set:N = \meta{integer}
+% \end{syntax}
+% Defines \meta{key} to set \meta{integer} to \meta{value} (which
+% must be an integer expression). If the variable does not exist, it
+% is created globally at the point that the key is set up. The key will
+% require a value at point-of-use unless a default is set.
+% \end{function}
+%
+% \begin{function}[updated = 2022-01-15]
+% {
+% .legacy_if_set:n, .legacy_if_gset:n,
+% .legacy_if_set_inverse:n, .legacy_if_gset_inverse:n
+% }
+% \begin{syntax}
+% \meta{key} .legacy_if_set:n = \meta{switch}
+% \end{syntax}
+% Defines \meta{key} to set legacy \cs[no-index]{if\meta{switch}} to \meta{value}
+% (which must be either \enquote{\texttt{true}} or \enquote{\texttt{false}}).
+% The \meta{switch} is the name of the switch \emph{without the leading
+% \texttt{if}}.
+%
+% The \texttt{inverse} versions will set the \meta{switch} to the logical
+% opposite of the \meta{value}.
+% \end{function}
+%
+% \begin{function}[updated = 2013-07-10]{.meta:n}
+% \begin{syntax}
+% \meta{key} .meta:n = \Arg{keyval list}
+% \end{syntax}
+% Makes \meta{key} a meta-key, which will set \meta{keyval list} in
+% one go. The \meta{keyval list} can refer as |#1| to the value given
+% at the time the \meta{key} is used (or, if no value is given, the
+% \meta{key}'s default value).
+% \end{function}
+%
+% \begin{function}[added = 2013-07-10]{.meta:nn}
+% \begin{syntax}
+% \meta{key} .meta:nn = \Arg{path} \Arg{keyval list}
+% \end{syntax}
+% Makes \meta{key} a meta-key, which will set \meta{keyval list} in
+% one go using the \meta{path} in place of the current one. The
+% \meta{keyval list} can refer as |#1| to the value given at the time
+% the \meta{key} is used (or, if no value is given, the \meta{key}'s
+% default value).
+% \end{function}
+%
+% \begin{function}[added = 2011-08-21]{.multichoice:}
+% \begin{syntax}
+% \meta{key} .multichoice:
+% \end{syntax}
+% Sets \meta{key} to act as a multiple choice key. Each valid choice
+% for \meta{key} must then be created, as discussed in
+% section~\ref{sec:l3keys:choice}.
+% \end{function}
+%
+% \begin{function}[added = 2011-08-21, updated = 2013-07-10]
+% {.multichoices:nn, .multichoices:Vn, .multichoices:en, .multichoices:on}
+% \begin{syntax}
+% \meta{key} .multichoices:nn \Arg{choices} \Arg{code}
+% \end{syntax}
+% Sets \meta{key} to act as a multiple choice key, and defines a series
+% \meta{choices}
+% which are implemented using the \meta{code}. Inside \meta{code},
+% \cs{l_keys_choice_tl} will be the name of the choice made, and
+% \cs{l_keys_choice_int} will be the position of the choice in the list
+% of \meta{choices} (indexed from~$1$).
+% Choices are discussed in detail in section~\ref{sec:l3keys:choice}.
+% \end{function}
+%
+% \begin{function}[added = 2019-05-05, updated = 2020-01-17]
+% {.muskip_set:N, .muskip_set:c, .muskip_gset:N, .muskip_gset:c}
+% \begin{syntax}
+% \meta{key} .muskip_set:N = \meta{muskip}
+% \end{syntax}
+% Defines \meta{key} to set \meta{muskip} to \meta{value} (which
+% must be a muskip expression). If the variable does not exist, it
+% is created globally at the point that the key is set up. The key will
+% require a value at point-of-use unless a default is set.
+% \end{function}
+%
+% \begin{function}[added = 2019-01-31]
+% {.prop_put:N, .prop_put:c, .prop_gput:N, .prop_gput:c}
+% \begin{syntax}
+% \meta{key} .prop_put:N = \meta{property list}
+% \end{syntax}
+% Defines \meta{key} to put the \meta{value} onto the \meta{property list}
+% stored under the \meta{key}.
+% If the variable does not exist, it
+% is created globally at the point that the key is set up.
+% \end{function}
+%
+% \begin{function}[updated = 2020-01-17]
+% {.skip_set:N, .skip_set:c, .skip_gset:N, .skip_gset:c}
+% \begin{syntax}
+% \meta{key} .skip_set:N = \meta{skip}
+% \end{syntax}
+% Defines \meta{key} to set \meta{skip} to \meta{value} (which
+% must be a skip expression). If the variable does not exist, it
+% is created globally at the point that the key is set up. The key will
+% require a value at point-of-use unless a default is set.
+% \end{function}
+%
+% \begin{function}[added = 2021-10-30]
+% {.str_set:N, .str_set:c, .str_gset:N, .str_gset:c}
+% \begin{syntax}
+% \meta{key} .str_set:N = \meta{string variable}
+% \end{syntax}
+% Defines \meta{key} to set \meta{string variable} to \meta{value}.
+% If the variable does not exist, it is created globally
+% at the point that the key is set up.
+% \end{function}
+%
+% \begin{function}[added = 2023-09-18]
+% {.str_set_e:N, .str_set_e:c, .str_gset_e:N, .str_gset_e:c}
+% \begin{syntax}
+% \meta{key} .str_set_e:N = \meta{string variable}
+% \end{syntax}
+% Defines \meta{key} to set \meta{string variable} to \meta{value},
+% which will be subjected to an \texttt{e}-type expansion
+% (\emph{i.e.}~using \cs{str_set:Ne}). If the variable does not exist,
+% it is created globally at the point that the key is set up.
+% \end{function}
+%
+% \begin{function}{.tl_set:N, .tl_set:c, .tl_gset:N, .tl_gset:c}
+% \begin{syntax}
+% \meta{key} .tl_set:N = \meta{token list variable}
+% \end{syntax}
+% Defines \meta{key} to set \meta{token list variable} to \meta{value}.
+% If the variable does not exist, it is created globally
+% at the point that the key is set up.
+% \end{function}
+%
+% \begin{function}[added = 2023-09-18]
+% {.tl_set_e:N, .tl_set_e:c, .tl_gset_e:N, .tl_gset_e:c}
+% \begin{syntax}
+% \meta{key} .tl_set_e:N = \meta{token list variable}
+% \end{syntax}
+% Defines \meta{key} to set \meta{token list variable} to \meta{value},
+% which will be subjected to an \texttt{e}-type expansion
+% (\emph{i.e.}~using \cs{tl_set:Ne}). If the variable does not exist,
+% it is created globally at the point that the key is set up.
+% \end{function}
+%
+% \begin{function}[added = 2015-07-14]{.undefine:}
+% \begin{syntax}
+% \meta{key} .undefine:
+% \end{syntax}
+% Removes the definition of the \meta{key} within the current \TeX{} group.
+% \end{function}
+%
+% \begin{function}[added = 2015-07-14]{.value_forbidden:n}
+% \begin{syntax}
+% \meta{key} .value_forbidden:n = \texttt{true\string|false}
+% \end{syntax}
+% Specifies that \meta{key} cannot receive a \meta{value} when used.
+% If a \meta{value} is given then an error will be issued. Setting
+% the property \enquote{\texttt{false}} cancels the restriction.
+% \end{function}
+%
+% \begin{function}[added = 2015-07-14]{.value_required:n}
+% \begin{syntax}
+% \meta{key} .value_required:n = \texttt{true\string|false}
+% \end{syntax}
+% Specifies that \meta{key} must receive a \meta{value} when used.
+% If a \meta{value} is not given then an error will be issued. Setting
+% the property \enquote{\texttt{false}} cancels the restriction.
+% \end{function}
+%
+% \section{Sub-dividing keys}
+% \label{sec:l3keys:subdivision}
+%
+% When creating large numbers of keys, it may be desirable to divide
+% them into several subsets for a given module. This can be achieved
+% either by adding a sub-division to the module name:
+% \begin{verbatim}
+% \keys_define:nn { mymodule / subset }
+% { key .code:n = code }
+% \end{verbatim}
+% or to the key name:
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% { subset / key .code:n = code }
+% \end{verbatim}
+% As illustrated, the best choice of token for sub-dividing keys in
+% this way is |/|. This is because of the method that is
+% used to represent keys internally. Both of the above code fragments
+% set the same key, which has full name \texttt{mymodule/subset/key}.
+%
+% As illustrated in the next section, this subdivision is
+% particularly relevant to making multiple choices.
+%
+% \section{Choice and multiple choice keys}
+% \label{sec:l3keys:choice}
+%
+% The \pkg{l3keys} system supports two types of choice key, in which a series
+% of pre-defined input values are linked to varying implementations. Choice
+% keys are usually created so that the various values are mutually-exclusive:
+% only one can apply at any one time. \enquote{Multiple} choice keys are also
+% supported: these allow a selection of values to be chosen at the same time.
+%
+% Mutually-exclusive choices are created by setting the \texttt{.choice:}
+% property:
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% { key .choice: }
+% \end{verbatim}
+% For keys which are set up as choices, the valid choices are generated
+% by creating sub-keys of the choice key. This can be carried out in
+% two ways.
+%
+% In many cases, choices execute similar code which is dependant only
+% on the name of the choice or the position of the choice in the
+% list of all possibilities. Here, the keys can share the same code, and can
+% be rapidly created using the \texttt{.choices:nn} property.
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key .choices:nn =
+% { choice-a, choice-b, choice-c }
+% {
+% You~gave~choice~'\tl_use:N \l_keys_choice_tl',~
+% which~is~in~position~\int_use:N \l_keys_choice_int \c_space_tl
+% in~the~list.
+% }
+% }
+% \end{verbatim}
+% The index \cs{l_keys_choice_int} in the list of choices starts at~$1$.
+%
+% \begin{variable}{\l_keys_choice_int, \l_keys_choice_tl}
+% Inside the code block for a choice generated using \texttt{.choices:nn},
+% the variables \cs{l_keys_choice_tl} and \cs{l_keys_choice_int} are
+% available to indicate the name of the current choice, and its position in
+% the comma list. The position is indexed from~$1$. Note that, as with
+% standard key code generated using \texttt{.code:n}, the value passed to
+% the key (i.e.~the choice name) is also available as |#1|.
+% \end{variable}
+%
+% On the other hand, it is sometimes useful to create choices which
+% use entirely different code from one another. This can be achieved
+% by setting the \texttt{.choice:} property of a key, then manually
+% defining sub-keys.
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key .choice:,
+% key / choice-a .code:n = code-a,
+% key / choice-b .code:n = code-b,
+% key / choice-c .code:n = code-c,
+% }
+% \end{verbatim}
+%
+% It is possible to mix the two methods, but manually-created choices
+% should \emph{not} use \cs{l_keys_choice_tl} or \cs{l_keys_choice_int}.
+% These variables do not have defined behaviour when used outside of
+% code created using \texttt{.choices:nn}
+% (\emph{i.e.}~anything might happen).
+%
+% It is possible to allow choice keys to take values which have not previously
+% been defined by adding code for the special \texttt{unknown} choice. The
+% general behavior of the \texttt{unknown} key is described in
+% Section~\ref{sec:l3keys:unknown}. A typical example in the case of a choice
+% would be to issue a custom error message:
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key .choice:,
+% key / choice-a .code:n = code-a,
+% key / choice-b .code:n = code-b,
+% key / choice-c .code:n = code-c,
+% key / unknown .code:n =
+% \msg_error:nneee { mymodule } { unknown-choice }
+% { key } % Name of choice key
+% { choice-a , choice-b , choice-c } % Valid choices
+% { \exp_not:n {#1} } % Invalid choice given
+% %
+% %
+% }
+% \end{verbatim}
+%
+% Multiple choices are created in a very similar manner to mutually-exclusive
+% choices, using the properties \texttt{.multichoice:} and
+% \texttt{.multichoices:nn}. As with mutually exclusive choices, multiple
+% choices are define as sub-keys. Thus both
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key .multichoices:nn =
+% { choice-a, choice-b, choice-c }
+% {
+% You~gave~choice~'\tl_use:N \l_keys_choice_tl',~
+% which~is~in~position~
+% \int_use:N \l_keys_choice_int \c_space_tl
+% in~the~list.
+% }
+% }
+% \end{verbatim}
+% and
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key .multichoice:,
+% key / choice-a .code:n = code-a,
+% key / choice-b .code:n = code-b,
+% key / choice-c .code:n = code-c,
+% }
+% \end{verbatim}
+% are valid.
+%
+% When a multiple choice key is set
+% \begin{verbatim}
+% \keys_set:nn { mymodule }
+% {
+% key = { a , b , c } % 'key' defined as a multiple choice
+% }
+% \end{verbatim}
+% each choice is applied in turn, equivalent to a \texttt{clist} mapping or
+% to applying each value individually:
+% \begin{verbatim}
+% \keys_set:nn { mymodule }
+% {
+% key = a ,
+% key = b ,
+% key = c ,
+% }
+% \end{verbatim}
+% Thus each separate choice will have passed to it the
+% \cs{l_keys_choice_tl} and \cs{l_keys_choice_int} in exactly
+% the same way as described for \texttt{.choices:nn}.
+%
+% \section{Key usage scope}
+%
+% Some keys will be used as settings which have a strictly limited scope
+% of usage. Some will be only available once, others will only be valid
+% until typesetting begins. To allow formats to support this in a structured
+% way, \pkg{l3keys} allows this information to be specified using the
+% \texttt{.usage:n} property.
+%
+% \begin{function}[added = 2022-01-10]{.usage:n}
+% \begin{syntax}
+% \meta{key} .usage:n = \meta{scope}
+% \end{syntax}
+% Defines the \meta{key} to have usage within the \meta{scope}, which
+% should be one of \texttt{general}, \texttt{preamble} or \texttt{load}.
+% \end{function}
+%
+% \begin{variable}[added = 2022-01-10]
+% {\l_keys_usage_load_prop, \l_keys_usage_preamble_prop}
+% \pkg{l3keys} itself does \emph{not} attempt to redefine keys based on the
+% usage scope. Rather, this information is made available with these
+% two property lists. These hold an entry for each module (prefix); the
+% value of each entry is a comma-separated list of the usage-restricted
+% key(s).
+% \end{variable}
+%
+% \section{Setting keys}
+%
+% \begin{function}[updated = 2017-11-14]
+% {
+% \keys_set:nn, \keys_set:nV, \keys_set:nv, \keys_set:ne,
+% \keys_set:no,
+% }
+% \begin{syntax}
+% \cs{keys_set:nn} \Arg{module} \Arg{keyval list}
+% \end{syntax}
+% Parses the \meta{keyval list}, and sets those keys which are defined
+% for \meta{module}. The behaviour on finding an unknown key can be set
+% by defining a special \texttt{unknown} key: this is illustrated
+% later.
+% \end{function}
+%
+% \begin{variable}[updated = 2020-02-08]
+% {\l_keys_path_str, \l_keys_key_str, \l_keys_value_tl}
+% For each key processed, information of the full \emph{path} of the
+% key, the \emph{name} of the key and the \emph{value} of the key is
+% available within two string and one token list variables.
+% These may be used within the code of the key.
+%
+% The \emph{path} of the key is a \enquote{full} description of the key,
+% and is unique for each key. It consists of the module and full key name,
+% thus for example
+% \begin{verbatim}
+% \keys_set:nn { mymodule } { key-a = some-value }
+% \end{verbatim}
+% has path \texttt{mymodule/key-a} while
+% \begin{verbatim}
+% \keys_set:nn { mymodule } { subset / key-a = some-value }
+% \end{verbatim}
+% has path \texttt{mymodule/subset/key-a}. This information is stored in
+% \cs{l_keys_path_str}.
+%
+% The \emph{name} of the key is the part of the path after the last
+% \texttt{/}, and thus is not unique. In the preceding examples, both keys
+% have name \texttt{key-a} despite having different paths. This information
+% is stored in \cs{l_keys_key_str}.
+%
+% The \emph{value} is everything after the \texttt{=}, which may be
+% empty if no value was given. This is stored in \cs{l_keys_value_tl}, and
+% is not processed in any way by \cs{keys_set:nn}.
+% \end{variable}
+%
+% \section{Handling of unknown keys}
+% \label{sec:l3keys:unknown}
+%
+% If a key has not previously been defined (is unknown), \cs{keys_set:nn}
+% looks for a special \texttt{unknown} key for the same module, and if this is
+% not defined raises an error indicating that the key name was unknown. This
+% mechanism can be used for example to issue custom error texts. The
+% \texttt{unknown} key also supports the \texttt{.default:n} property.
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% unknown .code:n =
+% You~tried~to~set~key~'\l_keys_key_str'~to~'#1'. ,
+% unknown .default:V = \c_novalue_tl
+% }
+% \end{verbatim}
+%
+% \begin{function}[added = 2011-08-23, updated = 2019-01-29]
+% {
+% \keys_set_known:nn, \keys_set_known:nV,
+% \keys_set_known:nv, \keys_set_known:ne,
+% \keys_set_known:no,
+% \keys_set_known:nnN, \keys_set_known:nVN,
+% \keys_set_known:nvN, \keys_set_known:neN,
+% \keys_set_known:noN,
+% \keys_set_known:nnnN, \keys_set_known:nVnN,
+% \keys_set_known:nvnN, \keys_set_known:nenN,
+% \keys_set_known:nonN
+% }
+% \begin{syntax}
+% \cs{keys_set_known:nn} \Arg{module} \Arg{keyval list}
+% \cs{keys_set_known:nnN} \Arg{module} \Arg{keyval list} \meta{tl}
+% \cs{keys_set_known:nnnN} \Arg{module} \Arg{keyval list} \Arg{root} \meta{tl}
+% \end{syntax}
+% These functions set keys which are known for the \meta{module}, and
+% simply ignore other keys. The \cs{keys_set_known:nn} function parses the
+% \meta{keyval list}, and sets those keys which are defined for
+% \meta{module}. Any keys which are unknown are not processed further by
+% the parser. In addition, \cs{keys_set_known:nnN} stores the key--value
+% pairs in the \meta{tl} in comma-separated form (\emph{i.e.}~an edited
+% version of the \meta{keyval list}). When a \meta{root} is given
+% (\cs{keys_set_known:nnnN}), the key--value entries are returned
+% relative to this point in the key tree. When it is absent, only the
+% key name and value are provided. The correct list is returned by
+% nested calls.
+% \end{function}
+%
+% \section{Selective key setting}
+% \label{sec:l3keys:selective}
+%
+% In some cases it may be useful to be able to select only some keys for
+% setting, even though these keys have the same path. For example, with
+% a set of keys defined using
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key-one .code:n = { \my_func:n {#1} } ,
+% key-two .tl_set:N = \l_my_a_tl ,
+% key-three .tl_set:N = \l_my_b_tl ,
+% key-four .fp_set:N = \l_my_a_fp ,
+% }
+% \end{verbatim}
+% the use of \cs{keys_set:nn} attempts to set all four keys. However, in
+% some contexts it may only be sensible to set some keys, or to control the
+% order of setting. To do this, keys may be assigned to \emph{groups}:
+% arbitrary sets which are independent of the key tree. Thus modifying the
+% example to read
+% \begin{verbatim}
+% \keys_define:nn { mymodule }
+% {
+% key-one .code:n = { \my_func:n {#1} } ,
+% key-one .groups:n = { first } ,
+% key-two .tl_set:N = \l_my_a_tl ,
+% key-two .groups:n = { first } ,
+% key-three .tl_set:N = \l_my_b_tl ,
+% key-three .groups:n = { second } ,
+% key-four .fp_set:N = \l_my_a_fp ,
+% }
+% \end{verbatim}
+% assigns \texttt{key-one} and \texttt{key-two} to group \texttt{first},
+% \texttt{key-three} to group \texttt{second}, while \texttt{key-four} is
+% not assigned to a group.
+%
+% Selective key setting may be achieved either by selecting one or more
+% groups to be made \enquote{active}, or by marking one or more groups to
+% be ignored in key setting.
+%
+% \begin{function}[added = 2024-01-10]
+% {
+% \keys_set_exclude_groups:nnn, \keys_set_exclude_groups:nnV,
+% \keys_set_exclude_groups:nnv, \keys_set_exclude_groups:nno,
+% \keys_set_exclude_groups:nnnN, \keys_set_exclude_groups:nnVN,
+% \keys_set_exclude_groups:nnvN, \keys_set_exclude_groups:nnoN,
+% \keys_set_exclude_groups:nnnnN, \keys_set_exclude_groups:nnVnN,
+% \keys_set_exclude_groups:nnvnN, \keys_set_exclude_groups:nnonN,
+% }
+% \begin{syntax}
+% \cs{keys_set_exclude_groups:nnn} \Arg{module} \Arg{groups} \Arg{keyval list}
+% \cs{keys_set_exclude_groups:nnnN} \Arg{module} \Arg{groups} \Arg{keyval list} \meta{tl}
+% \cs{keys_set_exclude_groups:nnnnN} \Arg{module} \Arg{groups} \Arg{keyval list} \meta{root} \meta{tl}
+% \end{syntax}
+% Sets keys by excluding those in the specificied \meta{groups}.
+% The \meta{groups} are
+% given as a comma-separated list. Unknown keys are not assigned to any
+% group and are thus always set. The key--value pairs for each
+% key which is filtered out are stored in the \meta{tl} in a
+% comma-separated form (\emph{i.e.}~an edited version of the \meta{keyval
+% list}). The \cs{keys_set_exclude_groups:nnn} version skips this stage.
+%
+% Use of \cs{keys_set_exclude_groups:nnnN} can be nested, with the correct residual
+% \meta{keyval list} returned at each stage. In the version which takes
+% a \meta{root} argument, the key list is returned relative to that point
+% in the key tree. In the cases without a \meta{root} argument, only
+% the key names and values are returned.
+% \end{function}
+%
+% \begin{function}[added = 2013-07-14, updated = 2017-05-27]
+% {
+% \keys_set_groups:nnn, \keys_set_groups:nnV,
+% \keys_set_groups:nnv, \keys_set_groups:nno
+% }
+% \begin{syntax}
+% \cs{keys_set_groups:nnn} \Arg{module} \Arg{groups} \Arg{keyval list}
+% \end{syntax}
+% Activates key filtering in an \enquote{opt-in} sense: only keys assigned to
+% one or more of the \meta{groups} specified are set. The \meta{groups} are
+% given as a comma-separated list. Unknown keys are not assigned to any
+% group and are thus never set.
+% \end{function}
+%
+% \section{Digesting keys}
+%
+% \begin{function}[added = 2022-03-09]{\keys_precompile:nnN}
+% \begin{syntax}
+% \cs{keys_precompile:nnN} \Arg{module} \Arg{keyval list} \meta{tl}
+% \end{syntax}
+% Parses the \meta{keyval list} as for \cs{keys_set:nn}, placing the
+% resulting code for those which set variables or functions into the
+% \meta{tl}. Thus this function \enquote{precompiles} the keyval list into
+% a set of results which can be applied rapidly.
+% \end{function}
+%
+% \section{Utility functions for keys}
+%
+% \begin{function}[EXP, pTF, updated = 2022-01-10]
+% {\keys_if_exist:nn, \keys_if_exist:ne}
+% \begin{syntax}
+% \cs{keys_if_exist_p:nn} \Arg{module} \Arg{key} \\
+% \cs{keys_if_exist:nnTF} \Arg{module} \Arg{key} \Arg{true code} \Arg{false code}
+% \end{syntax}
+% Tests if the \meta{key} exists for \meta{module}, \emph{i.e.}~if any code
+% has been defined for \meta{key}.
+% \end{function}
+%
+% \begin{function}[added = 2011-08-21,EXP,pTF, updated = 2017-11-14]
+% {\keys_if_choice_exist:nnn}
+% \begin{syntax}
+% \cs{keys_if_choice_exist_p:nnn} \Arg{module} \Arg{key} \Arg{choice} \\
+% \cs{keys_if_choice_exist:nnnTF} \Arg{module} \Arg{key} \Arg{choice} \Arg{true code} \Arg{false code}
+% \end{syntax}
+% Tests if the \meta{choice} is defined for the \meta{key} within the
+% \meta{module}, \emph{i.e.}~if any code has been defined for
+% \meta{key}/\meta{choice}. The test is \texttt{false} if the \meta{key}
+% itself is not defined.
+% \end{function}
+%
+% \begin{function}[updated = 2015-08-09]{\keys_show:nn}
+% \begin{syntax}
+% \cs{keys_show:nn} \Arg{module} \Arg{key}
+% \end{syntax}
+% Displays in the terminal
+% the information associated to the \meta{key} for a \meta{module},
+% including the function which is used to actually implement it.
+% \end{function}
+%
+% \begin{function}[added = 2014-08-22, updated = 2015-08-09]{\keys_log:nn}
+% \begin{syntax}
+% \cs{keys_log:nn} \Arg{module} \Arg{key}
+% \end{syntax}
+% Writes in the log file the information associated to the \meta{key}
+% for a \meta{module}. See also \cs{keys_show:nn} which displays the
+% result in the terminal.
+% \end{function}
+%
+% \section{Low-level interface for parsing key--val lists}
+%
+% To re-cap from earlier, a key--value list is input of the form
+% \begin{verbatim}
+% KeyOne = ValueOne ,
+% KeyTwo = ValueTwo ,
+% KeyThree
+% \end{verbatim}
+% where each key--value pair is separated by a comma from the rest of
+% the list, and each key--value pair does not necessarily contain an
+% equals sign or a value! Processing this type of input correctly
+% requires a number of careful steps, to correctly account for
+% braces, spaces and the category codes of separators.
+%
+% While the functions described earlier are used as a high-level interface
+% for processing such input, in special circumstances you may wish to use
+% a lower-level approach.
+% The low-level parsing system converts a \meta{key--value list}
+% into \meta{keys} and associated \meta{values}. After the parsing phase
+% is completed, the resulting keys and values (or keys alone) are
+% available for further processing. This processing is not carried out by the
+% low-level parser itself, and so the parser requires the names of
+% two functions along with the key--value list. One function is
+% needed to process key--value pairs (it receives two arguments),
+% and a second function is required for keys given without any value
+% (it is called with a single argument).
+%
+% The parser does not double |#| tokens or expand any input. Active
+% tokens |=| and |,| appearing at the outer level of braces are converted
+% to category \enquote{other} (12) so that the parser does not \enquote{miss}
+% any due to category code changes. Spaces are removed from the ends
+% of the keys and values. Keys and values which are given in braces
+% have exactly one set removed (after space trimming), thus
+% \begin{verbatim}
+% key = {value here},
+% \end{verbatim}
+% and
+% \begin{verbatim}
+% key = value here,
+% \end{verbatim}
+% are treated identically.
+%
+% \begin{function}[rEXP, added=2020-12-19, updated = 2021-05-10]
+% {\keyval_parse:nnn, \keyval_parse:nnV, \keyval_parse:nnv}
+% \begin{syntax}
+% \cs{keyval_parse:nnn} \Arg{code_1} \Arg{code_2} \Arg{key--value list}
+% \end{syntax}
+% Parses the \meta{key--value list} into a series of \meta{keys} and
+% associated \meta{values}, or keys alone (if no \meta{value} was
+% given). \meta{code_1} receives each \meta{key} (with no \meta{value}) as a
+% trailing brace group, whereas \meta{code_2} is appended by two brace groups,
+% the \meta{key} and \meta{value}.
+% The order of the \meta{keys} in the \meta{key--value list}
+% is preserved. Thus
+% \begin{verbatim}
+% \keyval_parse:nnn
+% { \use_none:nn { code 1 } }
+% { \use_none:nnn { code 2 } }
+% { key1 = value1 , key2 = value2, key3 = , key4 }
+% \end{verbatim}
+% is converted into an input stream
+% \begin{verbatim}
+% \use_none:nnn { code 2 } { key1 } { value1 }
+% \use_none:nnn { code 2 } { key2 } { value2 }
+% \use_none:nnn { code 2 } { key3 } { }
+% \use_none:nn { code 1 } { key4 }
+% \end{verbatim}
+% Note that there is a difference between an empty value (an equals
+% sign followed by nothing) and a missing value (no equals sign at
+% all). Spaces are trimmed from the ends of the \meta{key} and \meta{value},
+% then one \emph{outer} set of braces is removed from the \meta{key}
+% and \meta{value} as part of the processing. If you need exactly the output
+% shown above, you'll need to either \texttt{e}-type or \texttt{x}-type expand
+% the function.
+% \begin{texnote}
+% The result of each list element is returned within \cs{exp_not:n}, which
+% means that the converted input stream does not expand further when
+% appearing in an \texttt{e}-type or \texttt{x}-type argument expansion.
+% \end{texnote}
+% \end{function}
+%
+% \begin{function}[rEXP, updated = 2021-05-10]
+% {\keyval_parse:NNn, \keyval_parse:NNV, \keyval_parse:NNv}
+% \begin{syntax}
+% \cs{keyval_parse:NNn} \meta{function_1} \meta{function_2} \Arg{key--value list}
+% \end{syntax}
+% Parses the \meta{key--value list} into a series of \meta{keys} and
+% associated \meta{values}, or keys alone (if no \meta{value} was
+% given). \meta{function_1} should take one argument, while
+% \meta{function_2} should absorb two arguments. After
+% \cs{keyval_parse:NNn} has parsed the \meta{key--value list},
+% \meta{function_1} is used to process keys given with no value
+% and \meta{function_2} is used to process keys given with a
+% value. The order of the \meta{keys} in the \meta{key--value list}
+% is preserved. Thus
+% \begin{verbatim}
+% \keyval_parse:NNn \function:n \function:nn
+% { key1 = value1 , key2 = value2, key3 = , key4 }
+% \end{verbatim}
+% is converted into an input stream
+% \begin{verbatim}
+% \function:nn { key1 } { value1 }
+% \function:nn { key2 } { value2 }
+% \function:nn { key3 } { }
+% \function:n { key4 }
+% \end{verbatim}
+% Note that there is a difference between an empty value (an equals
+% sign followed by nothing) and a missing value (no equals sign at
+% all). Spaces are trimmed from the ends of the \meta{key} and \meta{value},
+% then one \emph{outer} set of braces is removed from the \meta{key}
+% and \meta{value} as part of the processing.
+%
+% This shares the implementation of \cs{keyval_parse:nnn}, the difference is
+% only semantically.
+% \begin{texnote}
+% The result is returned within \cs{exp_not:n}, which means that the
+% converted input stream does not expand further when appearing in an
+% \texttt{e}-type or \texttt{x}-type argument expansion.
+% \end{texnote}
+% \end{function}
+%
+% \end{documentation}
+%
+% \begin{implementation}
+%
+% \section{\pkg{l3keys} implementation}
+%
+% \begin{macrocode}
+%<*package>
+% \end{macrocode}
+%
+% \subsection{Low-level interface}
+%
+% The low-level key parser's implementation is based heavily on \pkg{expkv}.
+% Compared to \pkg{keyval} it adds a number of additional \enquote{safety}
+% requirements and allows to process the parsed list of key--value pairs in a
+% variety of ways. The net result is that this code needs around one and a half
+% the amount of time as \pkg{keyval} to parse the same list of keys. To optimise
+% speed as far as reasonably practical, a number of lower-level approaches are
+% taken rather than using the higher-level \pkg{expl3} interfaces.
+%
+% \begin{macrocode}
+%<@@=keyval>
+% \end{macrocode}
+%
+% \begin{variable}{\s_@@_nil,\s_@@_mark,\s_@@_stop,\s_@@_tail}
+% \begin{macrocode}
+\scan_new:N \s_@@_nil
+\scan_new:N \s_@@_mark
+\scan_new:N \s_@@_stop
+\scan_new:N \s_@@_tail
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l__kernel_keyval_allow_blank_keys_bool}
+% The general behavior of the \pkg{l3keys} module is to throw an error on
+% blank key names. However to support the usage of \cs{keyval_parse:nnn} in
+% the \pkg{l3prop} module we allow this error to be switched off temporarily
+% and just ignore blank names.
+% \begin{macrocode}
+\bool_new:N \l__kernel_keyval_allow_blank_keys_bool
+% \end{macrocode}
+% \end{variable}
+%
+% This temporary macro will be used since some of the definitions will need an
+% active comma or equals sign. Inside of this macro |#1| will be the active
+% comma and |#2| will be the active equals sign.
+% \begin{macrocode}
+\group_begin:
+ \cs_set_protected:Npn \@@_tmp:w #1#2
+ {
+% \end{macrocode}
+%
+% \begin{macro}[EXP]
+% {
+% \keyval_parse:nnn, \keyval_parse:nnV, \keyval_parse:nnv,
+% \keyval_parse:NNn, \keyval_parse:NNV, \keyval_parse:NNv
+% }
+% The main function starts the first of two loops. The outer loop splits the
+% key--value list at active commas, the inner loop will do so at other commas.
+% The use of \cs{s_@@_mark} here prevents loss of braces from the key
+% argument.
+% \begin{macrocode}
+ \cs_new:Npn \keyval_parse:nnn ##1 ##2 ##3
+ {
+ \__kernel_exp_not:w \tex_expanded:D
+ {
+ {
+ \@@_loop_active:nnw {##1} {##2}
+ \s_@@_mark ##3 #1 \s_@@_tail #1
+ }
+ }
+ }
+ \cs_new_eq:NN \keyval_parse:NNn \keyval_parse:nnn
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_loop_active:nnw}
+% First a fast test for the end of the loop is done, it'll gobble everything
+% up to a \cs{s_@@_tail}. The loop ending macro will gobble everything to the
+% last comma in this definition.
+% If the end isn't reached yet, start the second loop splitting at other
+% commas, the next iteration of this first loop will be inserted by the end of
+% \cs{@@_loop_other:nnw}.
+% \begin{macrocode}
+ \cs_new:Npn \@@_loop_active:nnw ##1 ##2 ##3 #1
+ {
+ \@@_if_recursion_tail:w ##3
+ \@@_end_loop_active:w \s_@@_tail
+ \@@_loop_other:nnw {##1} {##2} ##3 , \s_@@_tail ,
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_split_other:w, \@@_split_active:w}
+% These two macros allow to split at the first equals sign of category 12 or
+% 13. At the same time they also execute branching by inserting the first
+% token following \cs{s_@@_mark} that followed the equals sign. Hence they
+% also test for the presence of such an equals sign simultaneously.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_other:w ##1 = ##2 \s_@@_mark ##3
+ { ##3 ##1 \s_@@_stop \s_@@_mark ##2 }
+ \cs_new:Npn \@@_split_active:w ##1 #2 ##2 \s_@@_mark ##3
+ { ##3 ##1 \s_@@_stop \s_@@_mark ##2 }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_loop_other:nnw}
+% The second loop uses the same test for its end as the first loop, next it
+% splits at the first active equals sign using \cs{@@_split_active:w}. The
+% \cs{s_@@_nil} prevents accidental brace stripping and acts as a delimiter in
+% the next steps. First testing for an active equals sign will reduce the
+% number of necessary expansion steps for the expected average use case of
+% other equals signs and hence perform better on average.
+% \begin{macrocode}
+ \cs_new:Npn \@@_loop_other:nnw ##1 ##2 ##3 ,
+ {
+ \@@_if_recursion_tail:w ##3
+ \@@_end_loop_other:w \s_@@_tail
+ \@@_split_active:w ##3 \s_@@_nil
+ \s_@@_mark \@@_split_active_auxi:w
+ #2 \s_@@_mark \@@_clean_up_active:w
+ {##1} {##2}
+ \s_@@_mark
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_split_active_auxi:w}
+% \begin{macro}[EXP]{\@@_split_active_auxii:w}
+% \begin{macro}[EXP]{\@@_split_active_auxiii:w}
+% \begin{macro}[EXP]{\@@_split_active_auxiv:w}
+% \begin{macro}[EXP]{\@@_split_active_auxv:w}
+% After \cs{@@_split_active:w} the following will only be called if there was
+% at least one active equals sign in the current key--value pair. Therefore
+% this is the execution branch for a key--value pair with an active equals
+% sign. |##1| will be everything up to the first active equals sign. First it
+% tests for other equals signs in the key name, which will eventually throw an
+% error via \cs{@@_misplaced_equal_after_active_error:w}. If none was found we
+% forward the key to \cs{@@_split_active_auxii:w}.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_active_auxi:w ##1 \s_@@_stop
+ {
+ \@@_split_other:w ##1 \s_@@_nil
+ \s_@@_mark \@@_misplaced_equal_after_active_error:w
+ = \s_@@_mark \@@_split_active_auxii:w
+ }
+% \end{macrocode}
+% \cs{@@_split_active_auxii:w} gets the correct key name with a leading
+% \cs{s_@@_mark} as |##1|. It has to sanitise the remainder of the previous
+% test and trims the key name which will be forwarded to
+% \cs{@@_split_active_auxiii:w}.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_active_auxii:w
+ ##1 \s_@@_nil \s_@@_mark \@@_misplaced_equal_after_active_error:w
+ \s_@@_stop \s_@@_mark
+ ##2 \s_@@_nil #2 \s_@@_mark \@@_clean_up_active:w
+ { \@@_trim:nN {##1} \@@_split_active_auxiii:w ##2 \s_@@_nil }
+% \end{macrocode}
+% Next we test for a misplaced active equals sign in the value, if none is
+% found \cs{@@_split_active_auxiv:w} will be called.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_active_auxiii:w ##1 ##2 \s_@@_nil
+ {
+ \@@_split_active:w ##2 \s_@@_nil
+ \s_@@_mark \@@_misplaced_equal_in_split_error:w
+ #2 \s_@@_mark \@@_split_active_auxiv:w
+ {##1}
+ }
+% \end{macrocode}
+% This runs the last test after sanitising the remainder of the previous one.
+% This time test for a misplaced equals sign of category 12 in the value.
+% Finally the last auxiliary macro will be called.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_active_auxiv:w
+ ##1 \s_@@_nil \s_@@_mark \@@_misplaced_equal_in_split_error:w
+ \s_@@_stop \s_@@_mark
+ {
+ \@@_split_other:w ##1 \s_@@_nil
+ \s_@@_mark \@@_misplaced_equal_in_split_error:w
+ = \s_@@_mark \@@_split_active_auxv:w
+ }
+% \end{macrocode}
+% This last macro in this execution branch sanitises the last test, trims the
+% value and passes it to \cs{@@_pair:nnnn}.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_active_auxv:w
+ ##1 \s_@@_nil \s_@@_mark \@@_misplaced_equal_in_split_error:w
+ \s_@@_stop \s_@@_mark
+ { \@@_trim:nN { ##1 } \@@_pair:nnnn }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_clean_up_active:w}
+% The following is the branch taken if the key--value pair doesn't contain an
+% active equals sign. The remainder of that test will be cleaned up by
+% \cs{@@_clean_up_active:w} which will then split at an equals sign of
+% category other.
+% \begin{macrocode}
+ \cs_new:Npn \@@_clean_up_active:w
+ ##1 \s_@@_nil \s_@@_mark \@@_split_active_auxi:w \s_@@_stop \s_@@_mark
+ {
+ \@@_split_other:w ##1 \s_@@_nil
+ \s_@@_mark \@@_split_other_auxi:w
+ = \s_@@_mark \@@_clean_up_other:w
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_split_other_auxi:w}
+% \begin{macro}[EXP]{\@@_split_other_auxii:w}
+% \begin{macro}[EXP]{\@@_split_other_auxiii:w}
+% This is executed if the key--value pair doesn't contain an active equals
+% sign but at least one other. |##1| of \cs{@@_split_other_auxi:w} will
+% contain the complete key name, which is trimmed and forwarded to the next
+% auxiliary macro.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_other_auxi:w ##1 \s_@@_stop
+ { \@@_trim:nN { ##1 } \@@_split_other_auxii:w }
+% \end{macrocode}
+% We know that the value doesn't contain misplaced active equals signs but we
+% have to test for others. Also we need to sanitise the previous test, which
+% is done here and not earlier to avoid superfluous argument grabbing.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_other_auxii:w
+ ##1 ##2 \s_@@_nil = \s_@@_mark \@@_clean_up_other:w
+ {
+ \@@_split_other:w ##2 \s_@@_nil
+ \s_@@_mark \@@_misplaced_equal_in_split_error:w
+ = \s_@@_mark \@@_split_other_auxiii:w
+ { ##1 }
+ }
+% \end{macrocode}
+% \cs{@@_split_other_auxiii:w} sanitises the test for other equals signs,
+% trims the value and forwards it to \cs{@@_pair:nnnn}.
+% \begin{macrocode}
+ \cs_new:Npn \@@_split_other_auxiii:w
+ ##1 \s_@@_nil \s_@@_mark \@@_misplaced_equal_in_split_error:w
+ \s_@@_stop \s_@@_mark
+ { \@@_trim:nN { ##1 } \@@_pair:nnnn }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_clean_up_other:w}
+% \cs{@@_clean_up_other:w} is the last branch that might exist. It is called
+% if no equals sign was found, hence the only possibilities left are a blank
+% list element, which is to be skipped, or a lonely key. If it's no empty list
+% element this will trim the key name and forward it to \cs{@@_key:nn}.
+% \begin{macrocode}
+ \cs_new:Npn \@@_clean_up_other:w
+ ##1 \s_@@_nil \s_@@_mark \@@_split_other_auxi:w \s_@@_stop \s_@@_mark
+ {
+ \@@_if_blank:w ##1 \s_@@_nil \s_@@_stop \@@_blank_true:w
+ \s_@@_mark \s_@@_stop
+ \@@_trim:nN { ##1 } \@@_key:nn
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_misplaced_equal_after_active_error:w}
+% \begin{macro}[EXP]{\@@_misplaced_equal_in_split_error:w}
+% All these two macros do is gobble the remainder of the current other loop
+% execution and throw an error. Afterwards they have to insert the next loop
+% iteration.
+% \begin{macrocode}
+ \cs_new:Npn \@@_misplaced_equal_after_active_error:w
+ \s_@@_mark ##1 \s_@@_stop \s_@@_mark ##2 \s_@@_nil
+ = \s_@@_mark \@@_split_active_auxii:w
+ \s_@@_mark ##3 \s_@@_nil
+ #2 \s_@@_mark \@@_clean_up_active:w
+ {
+ \msg_expandable_error:nn
+ { keyval } { misplaced-equals-sign }
+ \@@_loop_other:nnw
+ }
+ \cs_new:Npn \@@_misplaced_equal_in_split_error:w
+ \s_@@_mark ##1 \s_@@_stop \s_@@_mark ##2 \s_@@_nil
+ ##3 \s_@@_mark ##4 ##5
+ {
+ \msg_expandable_error:nn
+ { keyval } { misplaced-equals-sign }
+ \@@_loop_other:nnw
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_end_loop_other:w, \@@_end_loop_active:w}
+% All that's left for the parsing loops are the macros which end the
+% recursion. Both just gobble the remaining tokens of the respective loop
+% including the next recursion call. \cs{@@_end_loop_other:w} also has to
+% insert the next iteration of the active loop.
+% \begin{macrocode}
+ \cs_new:Npn \@@_end_loop_other:w
+ \s_@@_tail
+ \@@_split_active:w
+ \s_@@_mark \s_@@_tail
+ \s_@@_nil \s_@@_mark
+ \@@_split_active_auxi:w
+ #2 \s_@@_mark \@@_clean_up_active:w
+ { \@@_loop_active:nnw }
+ \cs_new:Npn \@@_end_loop_active:w
+ \s_@@_tail
+ \@@_loop_other:nnw ##1 \s_@@_mark \s_@@_tail , \s_@@_tail ,
+ { }
+% \end{macrocode}
+% \end{macro}
+%
+% The parsing loops are done, so here ends the definition of \cs{@@_tmp:w},
+% which will finally set up the macros.
+% \begin{macrocode}
+ }
+ \char_set_catcode_active:n { `\, }
+ \char_set_catcode_active:n { `\= }
+ \@@_tmp:w , =
+\group_end:
+\cs_generate_variant:Nn \keyval_parse:NNn { NNV , NNv }
+\cs_generate_variant:Nn \keyval_parse:nnn { nnV , nnv }
+% \end{macrocode}
+%
+% \begin{macro}[EXP]{\@@_pair:nnnn, \@@_key:nn}
+% These macros will be called on the parsed keys and values of the key--value
+% list. All arguments are completely trimmed. They test for blank key names
+% and call the functions passed to \cs{keyval_parse:nnn} inside of
+% \cs{exp_not:n} with the correct arguments. Afterwards they insert the next
+% iteration of the other loop.
+% \begin{macrocode}
+\group_begin:
+ \cs_set_protected:Npn \@@_tmp:w #1#2
+ {
+ \cs_new:Npn \@@_pair:nnnn ##1 ##2 ##3 ##4
+ {
+ \@@_if_blank:w \s_@@_mark ##2 \s_@@_nil \s_@@_stop \@@_blank_key_error:w
+ \s_@@_mark \s_@@_stop
+ #1
+ \exp_not:n { ##4 {##2} {##1} }
+ #2
+ \@@_loop_other:nnw {##3} {##4}
+ }
+ \cs_new:Npn \@@_key:nn ##1 ##2
+ {
+ \@@_if_blank:w \s_@@_mark ##1 \s_@@_nil \s_@@_stop \@@_blank_key_error:w
+ \s_@@_mark \s_@@_stop
+ #1
+ \exp_not:n { ##2 {##1} }
+ #2
+ \@@_loop_other:nnw {##2}
+ }
+ }
+ \@@_tmp:w { } { }
+\group_end:
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_if_empty:w,\@@_if_blank:w,\@@_if_recursion_tail:w}
+% All these tests work by gobbling tokens until a certain combination is met,
+% which makes them pretty fast. The test for a blank argument should be called
+% with an arbitrary token following the argument. Each of these utilize the
+% fact that the argument will contain a leading \cs{s_@@_mark}.
+% \begin{macrocode}
+\cs_new:Npn \@@_if_empty:w #1 \s_@@_mark \s_@@_stop { }
+\cs_new:Npn \@@_if_blank:w \s_@@_mark #1 { \@@_if_empty:w \s_@@_mark }
+\cs_new:Npn \@@_if_recursion_tail:w \s_@@_mark #1 \s_@@_tail { }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_blank_true:w,\@@_blank_key_error:w}
+% These macros will be called if the tests above didn't gobble them, they
+% execute the branching.
+% \begin{macrocode}
+\cs_new:Npn \@@_blank_true:w \s_@@_mark \s_@@_stop \@@_trim:nN #1 \@@_key:nn
+ { \@@_loop_other:nnw }
+\cs_new:Npn \@@_blank_key_error:w \s_@@_mark \s_@@_stop #1 \@@_loop_other:nnw
+ {
+ \bool_if:NTF \l__kernel_keyval_allow_blank_keys_bool
+ { #1 }
+ { \msg_expandable_error:nn { keyval } { blank-key-name } }
+ \@@_loop_other:nnw
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% Two messages for the low level parsing system.
+% \begin{macrocode}
+\msg_new:nnn { keyval } { misplaced-equals-sign }
+ { Misplaced~'='~in~key-value~input~\msg_line_context: }
+\msg_new:nnn { keyval } { blank-key-name }
+ { Blank~key~name~in~key-value~input~\msg_line_context: }
+\prop_gput:Nnn \g_msg_module_name_prop { keyval } { LaTeX }
+\prop_gput:Nnn \g_msg_module_type_prop { keyval } { }
+% \end{macrocode}
+%
+% \begin{macro}[EXP]{\@@_trim:nN}
+% \begin{macro}[EXP]
+% {\@@_trim_auxi:w,\@@_trim_auxii:w,\@@_trim_auxiii:w,\@@_trim_auxiv:w}
+% And an adapted version of \cs{__tl_trim_spaces:nn} which is a bit faster for
+% our use case, as it can strip the braces at the end. This is pretty much the
+% same concept, so I won't comment on it here. The speed gain by using this
+% instead of \cs{tl_trim_spaces_apply:nN} is about 10\,\% of the total time for
+% \cs{keyval_parse:NNn} with one key and one key--value pair, so I think it's
+% worth it.
+% \begin{macrocode}
+\group_begin:
+ \cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new:Npn \@@_trim:nN ##1
+ {
+ \@@_trim_auxi:w
+ ##1
+ \s_@@_nil
+ \s_@@_mark #1 { }
+ \s_@@_mark \@@_trim_auxii:w
+ \@@_trim_auxiii:w
+ #1 \s_@@_nil
+ \@@_trim_auxiv:w
+ }
+ \cs_new:Npn \@@_trim_auxi:w ##1 \s_@@_mark #1 ##2 \s_@@_mark ##3
+ {
+ ##3
+ \@@_trim_auxi:w
+ \s_@@_mark
+ ##2
+ \s_@@_mark #1 {##1}
+ }
+ \cs_new:Npn \@@_trim_auxii:w \@@_trim_auxi:w \s_@@_mark \s_@@_mark ##1
+ {
+ \@@_trim_auxiii:w
+ ##1
+ }
+ \cs_new:Npn \@@_trim_auxiii:w ##1 #1 \s_@@_nil ##2
+ {
+ ##2
+ ##1 \s_@@_nil
+ \@@_trim_auxiii:w
+ }
+% \end{macrocode}
+% This is the one macro which differs from the original definition.
+% \begin{macrocode}
+ \cs_new:Npn \@@_trim_auxiv:w
+ \s_@@_mark ##1 \s_@@_nil
+ \@@_trim_auxiii:w \s_@@_nil \@@_trim_auxiii:w
+ ##2
+ { ##2 { ##1 } }
+ }
+ \@@_tmp:w { ~ }
+\group_end:
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Constants and variables}
+%
+% \begin{macrocode}
+%<@@=keys>
+% \end{macrocode}
+%
+% \begin{variable}
+% {
+% \c_@@_code_root_str ,
+% \c_@@_check_root_str ,
+% \c_@@_default_root_str ,
+% \c_@@_groups_root_str ,
+% \c_@@_inherit_root_str ,
+% \c_@@_type_root_str
+% }
+% Various storage areas for the different data which make up keys.
+% \begin{macrocode}
+\str_const:Nn \c_@@_code_root_str { key~code~>~ }
+\str_const:Nn \c_@@_check_root_str { key~check~>~ }
+\str_const:Nn \c_@@_default_root_str { key~default~>~ }
+\str_const:Nn \c_@@_groups_root_str { key~groups~>~ }
+\str_const:Nn \c_@@_inherit_root_str { key~inherit~>~ }
+\str_const:Nn \c_@@_type_root_str { key~type~>~ }
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\c_@@_props_root_str}
+% The prefix for storing properties.
+% \begin{macrocode}
+\str_const:Nn \c_@@_props_root_str { key~prop~>~ }
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_keys_choice_int, \l_keys_choice_tl}
+% Publicly accessible data on which choice is being used when several
+% are generated as a set.
+% \begin{macrocode}
+\int_new:N \l_keys_choice_int
+\tl_new:N \l_keys_choice_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_groups_clist}
+% Used for storing and recovering the list of groups which apply to a key:
+% set as a comma list but at one point we have to use this for a token
+% list recovery.
+% \begin{macrocode}
+\clist_new:N \l_@@_groups_clist
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_inherit_clist}
+% For normalisation.
+% \begin{macrocode}
+\clist_new:N \l_@@_inherit_clist
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_keys_key_str}
+% The name of a key itself: needed when setting keys.
+% \begin{macrocode}
+\str_new:N \l_keys_key_str
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}[deprecated]{\l_keys_key_tl}
+% The |tl| version is deprecated but has to be handled manually.
+% \begin{macrocode}
+\tl_new:N \l_keys_key_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_module_str}
+% The module for an entire set of keys.
+% \begin{macrocode}
+\str_new:N \l_@@_module_str
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_no_value_bool}
+% A marker is needed internally to show if only a key or a key plus a
+% value was seen: this is recorded here.
+% \begin{macrocode}
+\bool_new:N \l_@@_no_value_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_only_known_bool}
+% Used to track if only \enquote{known} keys are being set.
+% \begin{macrocode}
+\bool_new:N \l_@@_only_known_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_keys_path_str}
+% The \enquote{path} of the current key is stored here: this is
+% available to the programmer and so is public.
+% \begin{macrocode}
+\str_new:N \l_keys_path_str
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}[deprecated]{\l_keys_path_tl}
+% The older version is deprecated but has to be handled manually.
+% \begin{macrocode}
+\tl_new:N \l_keys_path_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_inherit_str}
+% \begin{macrocode}
+\str_new:N \l_@@_inherit_str
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_relative_tl}
+% The relative path for passing keys back to the user. As this can
+% be explicitly no-value, it must be a token list.
+% \begin{macrocode}
+\tl_new:N \l_@@_relative_tl
+\tl_set:Nn \l_@@_relative_tl { \q_@@_no_value }
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_property_str}
+% The \enquote{property} begin set for a key at definition time is
+% stored here.
+% \begin{macrocode}
+\str_new:N \l_@@_property_str
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_selective_bool, \l_@@_filtered_bool}
+% Two booleans for using key groups: one to indicate that \enquote{selective}
+% setting is active, a second to specify which type (\enquote{opt-in}
+% or \enquote{opt-out}).
+% \begin{macrocode}
+\bool_new:N \l_@@_selective_bool
+\bool_new:N \l_@@_filtered_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_selective_seq}
+% The list of key groups being filtered in or out during selective setting.
+% \begin{macrocode}
+\seq_new:N \l_@@_selective_seq
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_unused_clist}
+% Used when setting only some keys to store those left over.
+% \begin{macrocode}
+\clist_new:N \l_@@_unused_clist
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_keys_value_tl}
+% The value given for a key: may be empty if no value was given.
+% \begin{macrocode}
+\tl_new:N \l_keys_value_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_tmp_bool, \l_@@_tmpa_tl, \l_@@_tmpb_tl}
+% Scratch space.
+% \begin{macrocode}
+\bool_new:N \l_@@_tmp_bool
+\tl_new:N \l_@@_tmpa_tl
+\tl_new:N \l_@@_tmpb_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_precompile_bool, \l_@@_precompile_tl}
+% For digesting keys.
+% \begin{macrocode}
+\bool_new:N \l_@@_precompile_bool
+\tl_new:N \l_@@_precompile_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_keys_usage_load_prop, \l_keys_usage_preamble_prop}
+% Global data for document-level information.
+% \begin{macrocode}
+\prop_new:N \l_keys_usage_load_prop
+\prop_new:N \l_keys_usage_preamble_prop
+% \end{macrocode}
+% \end{variable}
+%
+% \subsubsection{Internal auxiliaries}
+%
+% \begin{variable}{\s_@@_nil,\s_@@_mark,\s_@@_stop}
+% Internal scan marks.
+% \begin{macrocode}
+\scan_new:N \s_@@_nil
+\scan_new:N \s_@@_mark
+\scan_new:N \s_@@_stop
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\q_@@_no_value}
+% Internal quarks.
+% \begin{macrocode}
+\quark_new:N \q_@@_no_value
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}[pTF]{\@@_quark_if_no_value:N}
+% Branching quark conditional.
+% \begin{macrocode}
+\__kernel_quark_new_conditional:Nn \@@_quark_if_no_value:N { TF }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_precompile:n}
+% An auxiliary to allow cleaner showing of code.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_precompile:n #1
+ {
+ \bool_if:NTF \l_@@_precompile_bool
+ { \tl_put_right:Nn \l_@@_precompile_tl }
+ { \use:n }
+ {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_cs_undefine:c}
+% Local version of \cs{cs_undefine:c} to avoid sprinkling
+% \cs{tex_undefined:D} everywhere.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_cs_undefine:c #1
+ {
+ \if_cs_exist:w #1 \cs_end:
+ \else:
+ \use_i:nnnn
+ \fi:
+ \cs_set_eq:cN {#1} \tex_undefined:D
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{The key defining mechanism}
+%
+% \begin{macro}{\keys_define:nn, \keys_define:ne, \keys_define:nx}
+% \begin{macro}{\@@_define:nnn, \@@_define:onn}
+% The public function for definitions is just a wrapper for the lower
+% level mechanism, more or less. The outer function is designed to
+% keep a track of the current module, to allow safe nesting. The module is set
+% removing any leading |/| (which is not needed here).
+% \begin{macrocode}
+\cs_new_protected:Npn \keys_define:nn
+ { \@@_define:onn \l_@@_module_str }
+\cs_generate_variant:Nn \keys_define:nn { ne , nx }
+\cs_new_protected:Npn \@@_define:nnn #1#2#3
+ {
+ \str_set:Ne \l_@@_module_str { \@@_trim_spaces:n {#2} }
+ \keyval_parse:NNn \@@_define:n \@@_define:nn {#3}
+ \str_set:Nn \l_@@_module_str {#1}
+ }
+\cs_generate_variant:Nn \@@_define:nnn { o }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_define:n}
+% \begin{macro}{\@@_define:nn}
+% \begin{macro}{\@@_define_aux:nn}
+% The outer functions here record whether a value was given and then
+% converge on a common internal mechanism. There is first a search for
+% a property in the current key name, then a check to make sure it is
+% known before the code hands off to the next step.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_define:n #1
+ {
+ \bool_set_true:N \l_@@_no_value_bool
+ \@@_define_aux:nn {#1} { }
+ }
+\cs_new_protected:Npn \@@_define:nn #1#2
+ {
+ \bool_set_false:N \l_@@_no_value_bool
+ \@@_define_aux:nn {#1} {#2}
+ }
+\cs_new_protected:Npn \@@_define_aux:nn #1#2
+ {
+ \@@_property_find:n {#1}
+ \cs_if_exist:cTF { \c_@@_props_root_str \l_@@_property_str }
+ { \@@_define_code:n {#2} }
+ {
+ \str_if_empty:NF \l_@@_property_str
+ {
+ \msg_error:nnee { keys } { property-unknown }
+ \l_@@_property_str \l_keys_path_str
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_property_find:n}
+% \begin{macro}[EXP]{\@@_property_find_auxi:w}
+% \begin{macro}{\@@_property_find_auxii:w}
+% \begin{macro}[EXP]
+% {
+% \@@_property_find_auxiii:w ,
+% \@@_property_find_auxiv:w
+% }
+% \begin{macro}{\@@_property_find_err:w}
+% Searching for a property means finding the last |.| in the input,
+% and storing the text before and after it. Everything is first turned into
+% strings, so there is no problem using \cs{cs_set_nopar:Npe} instead of
+% \cs{str_set:Ne} to set \cs{l_keys_path_str}. To gain further speed, brace
+% tricks are used and \cs{@@_property_find_auxiv:w} is defined as expandable.
+% Since spaces will already be trimmed from the module we can omit it from the
+% argument to \cs{@@_trim_spaces:n}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_property_find:n #1
+ {
+ \exp_after:wN \@@_property_find_auxi:w \tl_to_str:n {#1}
+ \s_@@_nil \@@_property_find_auxii:w
+ . \s_@@_nil \@@_property_find_err:w
+ }
+\cs_new:Npn \@@_property_find_auxi:w #1 . #2 \s_@@_nil #3
+ {
+ #3 #1 \s_@@_mark #2 \s_@@_nil #3
+ }
+\cs_new_protected:Npn \@@_property_find_auxii:w
+ #1 \s_@@_mark #2 \s_@@_nil \@@_property_find_auxii:w . \s_@@_nil
+ \@@_property_find_err:w
+ {
+ \cs_set_nopar:Npe \l_keys_path_str
+ {
+ \str_if_empty:NF \l_@@_module_str { \l_@@_module_str / }
+ \exp_after:wN \@@_trim_spaces:n \tex_expanded:D {{
+ #1
+ \if_false: }}} \fi:
+ \@@_property_find_auxi:w #2 \s_@@_nil \@@_property_find_auxiii:w
+ . \s_@@_nil \@@_property_find_auxiv:w
+ }
+\cs_new:Npn \@@_property_find_auxiii:w #1 \s_@@_mark #2 . #3 \s_@@_nil #4
+ {
+ . #1 #4 #2 \s_@@_mark #3 \s_@@_nil #4
+ }
+\cs_new:Npn \@@_property_find_auxiv:w
+ #1 \s_@@_nil \@@_property_find_auxiii:w
+ \s_@@_mark \s_@@_nil \@@_property_find_auxiv:w
+ {
+ \if_false: {{{ \fi: }}}
+ \cs_set_nopar:Npe \l_@@_property_str { . #1 }
+ \tl_set_eq:NN \l_keys_path_tl \l_keys_path_str
+ }
+\cs_new_protected:Npn \@@_property_find_err:w
+ #1 \s_@@_nil #2 \@@_property_find_err:w
+ {
+ \str_clear:N \l_@@_property_str
+ \msg_error:nnn { keys } { no-property } {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_define_code:n}
+% \begin{macro}[EXP]{\@@_define_code:w}
+% Two possible cases. If there is a value for the key, then just use
+% the function. If not, then a check to make sure there is no need for
+% a value with the property. If there should be one then complain,
+% otherwise execute it. There is no need to check for a |:| as if it
+% was missing the earlier tests would have failed.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_define_code:n #1
+ {
+ \bool_if:NTF \l_@@_no_value_bool
+ {
+ \exp_after:wN \@@_define_code:w
+ \l_@@_property_str \s_@@_stop
+ { \use:c { \c_@@_props_root_str \l_@@_property_str } }
+ {
+ \msg_error:nnee { keys } { property-requires-value }
+ \l_@@_property_str \l_keys_path_str
+ }
+ }
+ { \use:c { \c_@@_props_root_str \l_@@_property_str } {#1} }
+ }
+\exp_last_unbraced:NNNNo
+ \cs_new:Npn \@@_define_code:w #1 \c_colon_str #2 \s_@@_stop
+ { \tl_if_empty:nTF {#2} }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Turning properties into actions}
+%
+% \begin{macro}
+% {
+% \@@_bool_set:Nn, \@@_bool_set:cn,
+% \@@_bool_set_inverse:Nn, \@@_bool_set_inverse:cn
+% }
+% \begin{macro}{\@@_bool_set:Nnnn}
+% Boolean keys are really just choices, but all done by hand. The
+% second argument here is the scope: either empty or \texttt{ g } for
+% global.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_bool_set:Nn #1#2
+ { \@@_bool_set:Nnnn #1 {#2} { true } { false } }
+\cs_generate_variant:Nn \@@_bool_set:Nn { c }
+\cs_new_protected:Npn \@@_bool_set_inverse:Nn #1#2
+ { \@@_bool_set:Nnnn #1 {#2} { false } { true } }
+\cs_generate_variant:Nn \@@_bool_set_inverse:Nn { c }
+\cs_new_protected:Npn \@@_bool_set:Nnnn #1#2#3#4
+ {
+ \bool_if_exist:NF #1 { \bool_new:N #1 }
+ \@@_choice_make:
+ \@@_cmd_set:ne { \l_keys_path_str / true }
+ { \exp_not:c { bool_ #2 set_ #3 :N } \exp_not:N #1 }
+ \@@_cmd_set:ne { \l_keys_path_str / false }
+ { \exp_not:c { bool_ #2 set_ #4 :N } \exp_not:N #1 }
+ \@@_cmd_set_direct:nn { \l_keys_path_str / unknown }
+ {
+ \msg_error:nne { keys } { boolean-values-only }
+ \l_keys_path_str
+ }
+ \@@_default_set:n { true }
+ }
+\cs_generate_variant:Nn \@@_bool_set:Nn { c }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_choice_make:, \@@_multichoice_make:}
+% \begin{macro}{\@@_choice_make:N}
+% \begin{macro}{\@@_choice_make_aux:N}
+% To make a choice from a key, two steps: set the code, and set the
+% unknown key. As multichoices and choices are essentially the same bar one
+% function, the code is given together.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_choice_make:
+ { \@@_choice_make:N \@@_choice_find:n }
+\cs_new_protected:Npn \@@_multichoice_make:
+ { \@@_choice_make:N \@@_multichoice_find:n }
+\cs_new_protected:Npn \@@_choice_make:N #1
+ {
+ \cs_if_exist:cTF
+ { \c_@@_type_root_str \@@_parent:o \l_keys_path_str }
+ {
+ \str_if_eq:vnTF
+ { \c_@@_type_root_str \@@_parent:o \l_keys_path_str }
+ { choice }
+ {
+ \msg_error:nnee { keys } { nested-choice-key }
+ \l_keys_path_tl { \@@_parent:o \l_keys_path_str }
+ }
+ { \@@_choice_make_aux:N #1 }
+ }
+ { \@@_choice_make_aux:N #1 }
+ }
+\cs_new_protected:Npn \@@_choice_make_aux:N #1
+ {
+ \cs_set_nopar:cpn { \c_@@_type_root_str \l_keys_path_str }
+ { choice }
+ \@@_cmd_set_direct:nn \l_keys_path_str { #1 {##1} }
+ \@@_cmd_set_direct:nn { \l_keys_path_str / unknown }
+ {
+ \msg_error:nnee { keys } { choice-unknown }
+ \l_keys_path_str {##1}
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_choices_make:nn, \@@_multichoices_make:nn}
+% \begin{macro}{\@@_choices_make:Nnn}
+% Auto-generating choices means setting up the root key as a choice, then
+% defining each choice in turn.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_choices_make:nn
+ { \@@_choices_make:Nnn \@@_choice_make: }
+\cs_new_protected:Npn \@@_multichoices_make:nn
+ { \@@_choices_make:Nnn \@@_multichoice_make: }
+\cs_new_protected:Npn \@@_choices_make:Nnn #1#2#3
+ {
+ #1
+ \int_zero:N \l_keys_choice_int
+ \clist_map_inline:nn {#2}
+ {
+ \int_incr:N \l_keys_choice_int
+ \@@_cmd_set:ne
+ { \l_keys_path_str / \@@_trim_spaces:n {##1} }
+ {
+ \tl_set:Nn \exp_not:N \l_keys_choice_tl {##1}
+ \int_set:Nn \exp_not:N \l_keys_choice_int
+ { \int_use:N \l_keys_choice_int }
+ \exp_not:n {#3}
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_cmd_set:nn, \@@_cmd_set:Vn, \@@_cmd_set:ne, \@@_cmd_set:Vo,
+% \@@_cmd_set_direct:nn
+% }
+% Setting the code for a key first logs if appropriate that we are
+% defining a new key, then saves the code.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_cmd_set:nn #1#2
+ { \@@_cmd_set_direct:nn {#1} { \@@_precompile:n {#2} } }
+\cs_generate_variant:Nn \@@_cmd_set:nn { ne , Vn , Vo }
+\cs_new_protected:Npn \@@_cmd_set_direct:nn #1#2
+ { \cs_set_protected:cpn { \c_@@_code_root_str #1 } ##1 {#2} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_cs_set:NNpn, \@@_cs_set:Ncpn}
+% Creating control sequences is a bit more tricky than other cases as
+% we need to pick up the |p| argument. To make the internals look clearer,
+% the trailing |n| argument here is just for appearance.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_cs_set:NNpn #1#2#3#
+ {
+ \cs_set_protected:cpe { \c_@@_code_root_str \l_keys_path_str } ##1
+ {
+ \@@_precompile:n
+ { #1 \exp_not:N #2 \exp_not:n {#3} {##1} }
+ }
+ \use_none:n
+ }
+\cs_generate_variant:Nn \@@_cs_set:NNpn { Nc }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_default_set:n}
+% Setting a default value is easy. These are stored using \cs{cs_set_nopar:cpe} as this
+% avoids any worries about whether a token list exists.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_default_set:n #1
+ {
+ \tl_if_empty:nTF {#1}
+ {
+ \@@_cs_undefine:c
+ { \c_@@_default_root_str \l_keys_path_str }
+ }
+ {
+ \cs_set_nopar:cpe
+ { \c_@@_default_root_str \l_keys_path_str }
+ { \exp_not:n {#1} }
+ \@@_value_requirement:nn { required } { false }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_groups_set:n}
+% Assigning a key to one or more groups uses comma lists. As the list of
+% groups only exists if there is anything to do, the setting is done using
+% a scratch list. For the usual grouping reasons we use the low-level
+% approach to undefining a list. We also use the low-level approach for
+% the other case to avoid tripping up the |check-declarations| code.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_groups_set:n #1
+ {
+ \clist_set:Ne \l_@@_groups_clist { \tl_to_str:n {#1} }
+ \clist_if_empty:NTF \l_@@_groups_clist
+ {
+ \@@_cs_undefine:c
+ { \c_@@_groups_root_str \l_keys_path_str }
+ }
+ {
+ \cs_set_eq:cN { \c_@@_groups_root_str \l_keys_path_str }
+ \l_@@_groups_clist
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_inherit:n}
+% Inheritance means ignoring anything already said about the key:
+% zap the lot and set up.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_inherit:n #1
+ {
+ \@@_undefine:
+ \clist_set:Nn \l_@@_inherit_clist {#1}
+ \cs_set_eq:cN { \c_@@_inherit_root_str \l_keys_path_str }
+ \l_@@_inherit_clist
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_initialise:n}
+% A set up for initialisation: just run the code if it exists.
+% We need to set the key string here, using the deprecated \texttt{tl}
+% as a piece of scratch space.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_initialise:n #1
+ {
+ \cs_if_exist:cTF
+ { \c_@@_inherit_root_str \@@_parent:o \l_keys_path_str }
+ { \@@_execute_inherit: }
+ {
+ \str_clear:N \l_@@_inherit_str
+ \cs_if_exist:cT { \c_@@_code_root_str \l_keys_path_str }
+ {
+ \exp_after:wN \@@_find_key_module:wNN
+ \l_keys_path_str \s_@@_stop
+ \l_keys_key_tl \l_keys_key_str
+ \tl_set_eq:NN \l_keys_key_tl \l_keys_key_str
+ \tl_set:Nn \l_keys_value_tl {#1}
+ \@@_execute:no \l_keys_path_str \l_keys_value_tl
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_legacy_if_set:nn, \@@_legacy_if_inverse:nn}
+% \begin{macro}{\@@_legacy_if_inverse:nnnn}
+% Much the same as \pkg{expl3} booleans, except we assume that the switch
+% exists.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_legacy_if_set:nn #1#2
+ { \@@_legacy_if_set:nnnn {#1} {#2} { true } { false } }
+\cs_new_protected:Npn \@@_legacy_if_set_inverse:nn #1#2
+ { \@@_legacy_if_set:nnnn {#1} {#2} { false } { true } }
+\cs_new_protected:Npn \@@_legacy_if_set:nnnn #1#2#3#4
+ {
+ \@@_choice_make:
+ \@@_cmd_set:ne { \l_keys_path_str / true }
+ { \exp_not:c { legacy_if_#2 set_ #3 :n } { \exp_not:n {#1} } }
+ \@@_cmd_set:ne { \l_keys_path_str / false }
+ { \exp_not:c { legacy_if_#2 set_ #4 :n } { \exp_not:n {#1} } }
+ \@@_cmd_set:nn { \l_keys_path_str / unknown }
+ {
+ \msg_error:nne { keys } { boolean-values-only }
+ \l_keys_path_str
+ }
+ \@@_default_set:n { true }
+ \cs_if_exist:cF { if#1 }
+ {
+ \cs:w newif \exp_after:wN \cs_end:
+ \cs:w if#1 \cs_end:
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_meta_make:n}
+% \begin{macro}{\@@_meta_make:nn}
+% To create a meta-key, simply set up to pass data through. The internal
+% function is used here as a meta key should respect the prevailing
+% filtering, etc.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_meta_make:n #1
+ {
+ \exp_args:NVo \@@_cmd_set_direct:nn \l_keys_path_str
+ {
+ \exp_after:wN \@@_set:nn \exp_after:wN
+ { \l_@@_module_str } {#1}
+ }
+ }
+\cs_new_protected:Npn \@@_meta_make:nn #1#2
+ {
+ \exp_args:NV \@@_cmd_set_direct:nn
+ \l_keys_path_str { \@@_set:nn {#1} {#2} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_prop_put:Nn, \@@_prop_put:cn}
+% Much the same as other variables, but needs a dedicated auxiliary.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_prop_put:Nn #1#2
+ {
+ \prop_if_exist:NF #1 { \prop_new:N #1 }
+ \exp_after:wN \@@_find_key_module:wNN \l_keys_path_str \s_@@_stop
+ \l_@@_tmpa_tl \l_@@_tmpb_tl
+ \@@_cmd_set:ne \l_keys_path_str
+ {
+ \exp_not:c { prop_ #2 put:Nnn }
+ \exp_not:N #1
+ { \l_@@_tmpb_tl }
+ \exp_not:n { {##1} }
+ }
+ }
+\cs_generate_variant:Nn \@@_prop_put:Nn { c }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_undefine:}
+% Undefining a key has to be done without \cs{cs_undefine:c} as that
+% function acts globally.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_undefine:
+ {
+ \clist_map_inline:nn
+ { code , default , groups , inherit , type , check }
+ {
+ \@@_cs_undefine:c
+ { \tl_use:c { c_@@_ ##1 _root_str } \l_keys_path_str }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_value_requirement:nn}
+% \begin{macro}{\@@_check_forbidden:, \@@_check_required:}
+% Validating key input is done using a second function which runs before
+% the main key code. Setting that up means setting it equal to a generic
+% stub which does the check. This approach makes the lookup very fast at
+% the cost of one additional csname per key that needs it. The cleanup here
+% has to know the structure of the following code.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_value_requirement:nn #1#2
+ {
+ \str_case:nnF {#2}
+ {
+ { true }
+ {
+ \cs_set_eq:cc
+ { \c_@@_check_root_str \l_keys_path_str }
+ { @@_check_ #1 : }
+ }
+ { false }
+ {
+ \cs_if_eq:ccT
+ { \c_@@_check_root_str \l_keys_path_str }
+ { @@_check_ #1 : }
+ {
+ \@@_cs_undefine:c
+ { \c_@@_check_root_str \l_keys_path_str }
+ }
+ }
+ }
+ {
+ \msg_error:nne { keys }
+ { boolean-values-only }
+ { .value_ #1 :n }
+ }
+ }
+\cs_new_protected:Npn \@@_check_forbidden:
+ {
+ \bool_if:NF \l_@@_no_value_bool
+ {
+ \msg_error:nnee { keys } { value-forbidden }
+ \l_keys_path_str \l_keys_value_tl
+ \use_none:nnn
+ }
+ }
+\cs_new_protected:Npn \@@_check_required:
+ {
+ \bool_if:NT \l_@@_no_value_bool
+ {
+ \msg_error:nne { keys } { value-required }
+ \l_keys_path_str
+ \use_none:nnn
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_usage:n}
+% \begin{macro}{\@@_usage:NN}
+% \begin{macro}{\@@_usage:w}
+% Save the relevant data.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_usage:n #1
+ {
+ \str_case:nnF {#1}
+ {
+ { general }
+ {
+ \@@_usage:NN \l_keys_usage_load_prop
+ \c_false_bool
+ \@@_usage:NN \l_keys_usage_preamble_prop
+ \c_false_bool
+ }
+ { load }
+ {
+ \@@_usage:NN \l_keys_usage_load_prop
+ \c_true_bool
+ \@@_usage:NN \l_keys_usage_preamble_prop
+ \c_false_bool
+ }
+ { preamble }
+ {
+ \@@_usage:NN \l_keys_usage_load_prop
+ \c_false_bool
+ \@@_usage:NN \l_keys_usage_preamble_prop
+ \c_true_bool
+ }
+ }
+ {
+ \msg_error:nnnn { keys }
+ { choice-unknown }
+ { .usage:n }
+ {#1}
+ }
+ }
+\cs_new_protected:Npn \@@_usage:NN #1#2
+ {
+ \prop_get:NVNF #1 \l_@@_module_str \l_@@_tmpa_tl
+ { \tl_clear:N \l_@@_tmpa_tl }
+ \tl_set:Ne \l_@@_tmpb_tl
+ { \exp_after:wN \@@_usage:w \l_keys_path_str \s_@@_stop }
+ \bool_if:NTF #2
+ { \clist_put_right:NV \l_@@_tmpa_tl \l_@@_tmpb_tl }
+ { \clist_remove_all:NV \l_@@_tmpa_tl \l_@@_tmpb_tl }
+ \prop_put:NVV #1 \l_@@_module_str
+ \l_@@_tmpa_tl
+ }
+\cs_new:Npn \@@_usage:w #1 / #2 \s_@@_stop {#2}
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_variable_set:NnnN, \@@_variable_set:cnnN}
+% \begin{macro}{\@@_variable_set_required:NnnN, \@@_variable_set_required:cnnN}
+% Setting a variable takes the type and scope separately so that
+% it is easy to make a new variable if needed.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_variable_set:NnnN #1#2#3#4
+ {
+ \use:c { #2_if_exist:NF } #1 { \use:c { #2 _new:N } #1 }
+ \@@_cmd_set:ne \l_keys_path_str
+ {
+ \exp_not:c { #2 _ #3 set:N #4 }
+ \exp_not:N #1
+ \exp_not:n { {##1} }
+ }
+ }
+\cs_generate_variant:Nn \@@_variable_set:NnnN { c }
+\cs_new_protected:Npn \@@_variable_set_required:NnnN #1#2#3#4
+ {
+ \@@_variable_set:NnnN #1 {#2} {#3} #4
+ \@@_value_requirement:nn { required } { true }
+ }
+\cs_generate_variant:Nn \@@_variable_set_required:NnnN { c }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Creating key properties}
+%
+% The key property functions are all wrappers for internal functions,
+% meaning that things stay readable and can also be altered later on.
+%
+% Importantly, while key properties have \enquote{normal} argument specs, the
+% underlying code always supplies one braced argument to these. As such, argument
+% expansion is handled by hand rather than using the standard tools. This shows
+% up particularly for the two-argument properties, where things would otherwise
+% go badly wrong.
+%
+% \begin{macro}{.bool_set:N, .bool_set:c}
+% \begin{macro}{.bool_gset:N, .bool_gset:c}
+% One function for this.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_set:N } #1
+ { \@@_bool_set:Nn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_set:c } #1
+ { \@@_bool_set:cn {#1} { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_gset:N } #1
+ { \@@_bool_set:Nn #1 { g } }
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_gset:c } #1
+ { \@@_bool_set:cn {#1} { g } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.bool_set_inverse:N, .bool_set_inverse:c}
+% \begin{macro}{.bool_gset_inverse:N, .bool_gset_inverse:c}
+% One function for this.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_set_inverse:N } #1
+ { \@@_bool_set_inverse:Nn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_set_inverse:c } #1
+ { \@@_bool_set_inverse:cn {#1} { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_gset_inverse:N } #1
+ { \@@_bool_set_inverse:Nn #1 { g } }
+\cs_new_protected:cpn { \c_@@_props_root_str .bool_gset_inverse:c } #1
+ { \@@_bool_set_inverse:cn {#1} { g } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.choice:}
+% Making a choice is handled internally, as it is also needed by
+% \texttt{.generate_choices:n}.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .choice: }
+ { \@@_choice_make: }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.choices:nn, .choices:Vn, .choices:en, .choices:on, .choices:xn}
+% For auto-generation of a series of mutually-exclusive choices.
+% Here, |#1| consists of two separate
+% arguments, hence the slightly odd-looking implementation.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .choices:nn } #1
+ { \@@_choices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .choices:Vn } #1
+ { \exp_args:NV \@@_choices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .choices:en } #1
+ { \exp_args:Ne \@@_choices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .choices:on } #1
+ { \exp_args:No \@@_choices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .choices:xn } #1
+ { \exp_args:Nx \@@_choices_make:nn #1 }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.code:n}
+% Creating code is simply a case of passing through to the underlying
+% \texttt{set} function.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .code:n } #1
+ { \@@_cmd_set:nn \l_keys_path_str {#1} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.clist_set:N, .clist_set:c}
+% \begin{macro}{.clist_gset:N, .clist_gset:c}
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .clist_set:N } #1
+ { \@@_variable_set:NnnN #1 { clist } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .clist_set:c } #1
+ { \@@_variable_set:cnnN {#1} { clist } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .clist_gset:N } #1
+ { \@@_variable_set:NnnN #1 { clist } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .clist_gset:c } #1
+ { \@@_variable_set:cnnN {#1} { clist } { g } n }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {.cs_set:Np, .cs_set:cp, .cs_set_protected:Np, .cs_set_protected:cp}
+% \begin{macro}
+% {.cs_gset:Np, .cs_gset:cp, .cs_gset_protected:Np, .cs_gset_protected:cp}
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_set:Np } #1
+ { \@@_cs_set:NNpn \cs_set:Npn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_set:cp } #1
+ { \@@_cs_set:Ncpn \cs_set:Npn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_set_protected:Np } #1
+ { \@@_cs_set:NNpn \cs_set_protected:Npn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_set_protected:cp } #1
+ { \@@_cs_set:Ncpn \cs_set_protected:Npn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_gset:Np } #1
+ { \@@_cs_set:NNpn \cs_gset:Npn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_gset:cp } #1
+ { \@@_cs_set:Ncpn \cs_gset:Npn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_gset_protected:Np } #1
+ { \@@_cs_set:NNpn \cs_gset_protected:Npn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .cs_gset_protected:cp } #1
+ { \@@_cs_set:Ncpn \cs_gset_protected:Npn #1 { } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.default:n, .default:V, .default:e, .default:o, .default:x}
+% Expansion is left to the internal functions.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .default:n } #1
+ { \@@_default_set:n {#1} }
+\cs_new_protected:cpn { \c_@@_props_root_str .default:V } #1
+ { \exp_args:NV \@@_default_set:n #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .default:e } #1
+ { \exp_args:Ne \@@_default_set:n {#1} }
+\cs_new_protected:cpn { \c_@@_props_root_str .default:o } #1
+ { \exp_args:No \@@_default_set:n {#1} }
+\cs_new_protected:cpn { \c_@@_props_root_str .default:x } #1
+ { \exp_args:Nx \@@_default_set:n {#1} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.dim_set:N, .dim_set:c}
+% \begin{macro}{.dim_gset:N, .dim_gset:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .dim_set:N } #1
+ { \@@_variable_set_required:NnnN #1 { dim } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .dim_set:c } #1
+ { \@@_variable_set_required:cnnN {#1} { dim } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .dim_gset:N } #1
+ { \@@_variable_set_required:NnnN #1 { dim } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .dim_gset:c } #1
+ { \@@_variable_set_required:cnnN {#1} { dim } { g } n }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.fp_set:N, .fp_set:c}
+% \begin{macro}{.fp_gset:N, .fp_gset:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .fp_set:N } #1
+ { \@@_variable_set_required:NnnN #1 { fp } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .fp_set:c } #1
+ { \@@_variable_set_required:cnnN {#1} { fp } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .fp_gset:N } #1
+ { \@@_variable_set_required:NnnN #1 { fp } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .fp_gset:c } #1
+ { \@@_variable_set_required:cnnN {#1} { fp } { g } n }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.groups:n}
+% A single property to create groups of keys.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .groups:n } #1
+ { \@@_groups_set:n {#1} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.inherit:n}
+% Nothing complex: only one variant at the moment!
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .inherit:n } #1
+ { \@@_inherit:n {#1} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.initial:n, .initial:V, .initial:e, .initial:o, .initial:x}
+% The standard hand-off approach.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .initial:n } #1
+ { \@@_initialise:n {#1} }
+\cs_new_protected:cpn { \c_@@_props_root_str .initial:V } #1
+ { \exp_args:NV \@@_initialise:n #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .initial:e } #1
+ { \exp_args:Ne \@@_initialise:n {#1} }
+\cs_new_protected:cpn { \c_@@_props_root_str .initial:o } #1
+ { \exp_args:No \@@_initialise:n {#1} }
+\cs_new_protected:cpn { \c_@@_props_root_str .initial:x } #1
+ { \exp_args:Nx \@@_initialise:n {#1} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.int_set:N, .int_set:c}
+% \begin{macro}{.int_gset:N, .int_gset:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .int_set:N } #1
+ { \@@_variable_set_required:NnnN #1 { int } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .int_set:c } #1
+ { \@@_variable_set_required:cnnN {#1} { int } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .int_gset:N } #1
+ { \@@_variable_set_required:NnnN #1 { int } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .int_gset:c } #1
+ { \@@_variable_set_required:cnnN {#1} { int } { g } n }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% .legacy_if_set:n, .legacy_if_gset:n,
+% .legacy_if_set_inverse:n, .legacy_if_gset_inverse:n
+% }
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .legacy_if_set:n } #1
+ { \@@_legacy_if_set:nn {#1} { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .legacy_if_gset:n } #1
+ { \@@_legacy_if_set:nn {#1} { g } }
+\cs_new_protected:cpn { \c_@@_props_root_str .legacy_if_set_inverse:n } #1
+ { \@@_legacy_if_set_inverse:nn {#1} { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .legacy_if_gset_inverse:n } #1
+ { \@@_legacy_if_set_inverse:nn {#1} { g } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.meta:n}
+% Making a meta is handled internally.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .meta:n } #1
+ { \@@_meta_make:n {#1} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.meta:nn}
+% Meta with path: potentially lots of variants, but for the moment
+% no so many defined.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .meta:nn } #1
+ { \@@_meta_make:nn #1 }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.multichoice:}
+% \begin{macro}{.multichoices:nn, .multichoices:Vn, .multichoices:en, .multichoices:on, .multichoices:xn}
+% The same idea as \texttt{.choice:} and \texttt{.choices:nn}, but
+% where more than one choice is allowed.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .multichoice: }
+ { \@@_multichoice_make: }
+\cs_new_protected:cpn { \c_@@_props_root_str .multichoices:nn } #1
+ { \@@_multichoices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .multichoices:Vn } #1
+ { \exp_args:NV \@@_multichoices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .multichoices:en } #1
+ { \exp_args:Ne \@@_multichoices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .multichoices:on } #1
+ { \exp_args:No \@@_multichoices_make:nn #1 }
+\cs_new_protected:cpn { \c_@@_props_root_str .multichoices:xn } #1
+ { \exp_args:Nx \@@_multichoices_make:nn #1 }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.muskip_set:N, .muskip_set:c, .muskip_gset:N, .muskip_gset:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .muskip_set:N } #1
+ { \@@_variable_set_required:NnnN #1 { muskip } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .muskip_set:c } #1
+ { \@@_variable_set_required:cnnN {#1} { muskip } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .muskip_gset:N } #1
+ { \@@_variable_set_required:NnnN #1 { muskip } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .muskip_gset:c } #1
+ { \@@_variable_set_required:cnnN {#1} { muskip } { g } n }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.prop_put:N, .prop_put:c, .prop_gput:N, .prop_gput:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .prop_put:N } #1
+ { \@@_prop_put:Nn #1 { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .prop_put:c } #1
+ { \@@_prop_put:cn {#1} { } }
+\cs_new_protected:cpn { \c_@@_props_root_str .prop_gput:N } #1
+ { \@@_prop_put:Nn #1 { g } }
+\cs_new_protected:cpn { \c_@@_props_root_str .prop_gput:c } #1
+ { \@@_prop_put:cn {#1} { g } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.skip_set:N, .skip_set:c}
+% \begin{macro}{.skip_gset:N, .skip_gset:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .skip_set:N } #1
+ { \@@_variable_set_required:NnnN #1 { skip } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .skip_set:c } #1
+ { \@@_variable_set_required:cnnN {#1} { skip } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .skip_gset:N } #1
+ { \@@_variable_set_required:NnnN #1 { skip } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .skip_gset:c } #1
+ { \@@_variable_set_required:cnnN {#1} { skip } { g } n }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.str_set:N, .str_set:c}
+% \begin{macro}{.str_gset:N, .str_gset:c}
+% \begin{macro}{.str_set_e:N, .str_set_e:c}
+% \begin{macro}{.str_gset_e:N, .str_gset_e:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .str_set:N } #1
+ { \@@_variable_set:NnnN #1 { str } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .str_set:c } #1
+ { \@@_variable_set:cnnN {#1} { str } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .str_set_e:N } #1
+ { \@@_variable_set:NnnN #1 { str } { } e }
+\cs_new_protected:cpn { \c_@@_props_root_str .str_set_e:c } #1
+ { \@@_variable_set:cnnN {#1} { str } { } e }
+\cs_new_protected:cpn { \c_@@_props_root_str .str_gset:N } #1
+ { \@@_variable_set:NnnN #1 { str } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .str_gset:c } #1
+ { \@@_variable_set:cnnN {#1} { str } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .str_gset_e:N } #1
+ { \@@_variable_set:NnnN #1 { str } { g } e }
+\cs_new_protected:cpn { \c_@@_props_root_str .str_gset_e:c } #1
+ { \@@_variable_set:cnnN {#1} { str } { g } e }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.tl_set:N, .tl_set:c}
+% \begin{macro}{.tl_gset:N, .tl_gset:c}
+% \begin{macro}{.tl_set_e:N, .tl_set_e:c}
+% \begin{macro}{.tl_gset_e:N, .tl_gset_e:c}
+% Setting a variable is very easy: just pass the data along.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_set:N } #1
+ { \@@_variable_set:NnnN #1 { tl } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_set:c } #1
+ { \@@_variable_set:cnnN {#1} { tl } { } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_set_e:N } #1
+ { \@@_variable_set:NnnN #1 { tl } { } e }
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_set_e:c } #1
+ { \@@_variable_set:cnnN {#1} { tl } { } e }
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_gset:N } #1
+ { \@@_variable_set:NnnN #1 { tl } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_gset:c } #1
+ { \@@_variable_set:cnnN {#1} { tl } { g } n }
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_gset_e:N } #1
+ { \@@_variable_set:NnnN #1 { tl } { g } e }
+\cs_new_protected:cpn { \c_@@_props_root_str .tl_gset_e:c } #1
+ { \@@_variable_set:cnnN {#1} { tl } { g } e }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{.undefine:}
+% Another simple wrapper.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .undefine: }
+ { \@@_undefine: }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.usage:n}
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .usage:n } #1
+ { \@@_usage:n {#1} }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{.value_forbidden:n}
+% \begin{macro}{.value_required:n}
+% These are very similar, so both call the same function.
+% \begin{macrocode}
+\cs_new_protected:cpn { \c_@@_props_root_str .value_forbidden:n } #1
+ { \@@_value_requirement:nn { forbidden } {#1} }
+\cs_new_protected:cpn { \c_@@_props_root_str .value_required:n } #1
+ { \@@_value_requirement:nn { required } {#1} }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Setting keys}
+%
+% \begin{macro}
+% {
+% \keys_set:nn, \keys_set:nV, \keys_set:nv, \keys_set:ne,
+% \keys_set:no, \keys_set:nx,
+% \@@_set:nn
+% }
+% \begin{macro}{\@@_set:nnn}
+% A simple wrapper allowing for nesting.
+% \begin{macrocode}
+\cs_new_protected:Npn \keys_set:nn #1#2
+ {
+ \use:e
+ {
+ \bool_set_false:N \exp_not:N \l_@@_only_known_bool
+ \bool_set_false:N \exp_not:N \l_@@_filtered_bool
+ \bool_set_false:N \exp_not:N \l_@@_selective_bool
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl
+ { \exp_not:N \q_@@_no_value }
+ \@@_set:nn \exp_not:n { {#1} {#2} }
+ \bool_if:NT \l_@@_only_known_bool
+ { \bool_set_true:N \exp_not:N \l_@@_only_known_bool }
+ \bool_if:NT \l_@@_filtered_bool
+ { \bool_set_true:N \exp_not:N \l_@@_filtered_bool }
+ \bool_if:NT \l_@@_selective_bool
+ { \bool_set_true:N \exp_not:N \l_@@_selective_bool }
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl
+ { \exp_not:o \l_@@_relative_tl }
+ }
+ }
+\cs_generate_variant:Nn \keys_set:nn { nV , nv , ne , no , nx }
+\cs_new_protected:Npn \@@_set:nn #1#2
+ { \exp_args:No \@@_set:nnn \l_@@_module_str {#1} {#2} }
+\cs_new_protected:Npn \@@_set:nnn #1#2#3
+ {
+ \str_set:Ne \l_@@_module_str { \@@_trim_spaces:n {#2} }
+ \keyval_parse:NNn \@@_set_keyval:n \@@_set_keyval:nn {#3}
+ \str_set:Nn \l_@@_module_str {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \keys_set_known:nnN, \keys_set_known:nVN,
+% \keys_set_known:nvN, \keys_set_known:neN,
+% \keys_set_known:noN
+% }
+% \begin{macro}
+% {
+% \keys_set_known:nnnN, \keys_set_known:nVnN,
+% \keys_set_known:nvnN, \keys_set_known:nenN,
+% \keys_set_known:nonN
+% }
+% \begin{macro}{\@@_set_known:nnnnN}
+% \begin{macro}
+% {
+% \keys_set_known:nn, \keys_set_known:nV,
+% \keys_set_known:nv, \keys_set_known:ne,
+% \keys_set_known:no
+% }
+% \begin{macro}{\@@_set_known:nnn}
+% Setting known keys simply means setting the appropriate boolean, then
+% running the standard code. To allow for nested setting, any existing
+% value of \cs{l_@@_unused_clist} is saved on the stack and reset
+% afterwards. Note that for speed/simplicity reasons we use a \texttt{tl}
+% operation to set the \texttt{clist} here!
+% \begin{macrocode}
+\cs_new_protected:Npn \keys_set_known:nnN #1#2#3
+ {
+ \exp_args:No \@@_set_known:nnnnN
+ \l_@@_unused_clist \q_@@_no_value {#1} {#2} #3
+ }
+\cs_generate_variant:Nn \keys_set_known:nnN { nV , nv , ne , no }
+\cs_new_protected:Npn \keys_set_known:nnnN #1#2#3#4
+ {
+ \exp_args:No \@@_set_known:nnnnN
+ \l_@@_unused_clist {#3} {#1} {#2} #4
+ }
+\cs_generate_variant:Nn \keys_set_known:nnnN { nV , nv , ne , no }
+\cs_new_protected:Npn \@@_set_known:nnnnN #1#2#3#4#5
+ {
+ \clist_clear:N \l_@@_unused_clist
+ \@@_set_known:nnn {#2} {#3} {#4}
+ \__kernel_tl_set:Nx #5 { \exp_not:o \l_@@_unused_clist }
+ \__kernel_tl_set:Nx \l_@@_unused_clist { \exp_not:n {#1} }
+ }
+\cs_new_protected:Npn \keys_set_known:nn #1#2
+ { \@@_set_known:nnn \q_@@_no_value {#1} {#2} }
+\cs_generate_variant:Nn \keys_set_known:nn { nV , nv , ne , no }
+\cs_new_protected:Npn \@@_set_known:nnn #1#2#3
+ {
+ \use:e
+ {
+ \bool_set_true:N \exp_not:N \l_@@_only_known_bool
+ \bool_set_false:N \exp_not:N \l_@@_filtered_bool
+ \bool_set_false:N \exp_not:N \l_@@_selective_bool
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl { \exp_not:n {#1} }
+ \@@_set:nn \exp_not:n { {#2} {#3} }
+ \bool_if:NF \l_@@_only_known_bool
+ { \bool_set_false:N \exp_not:N \l_@@_only_known_bool }
+ \bool_if:NT \l_@@_filtered_bool
+ { \bool_set_true:N \exp_not:N \l_@@_filtered_bool }
+ \bool_if:NT \l_@@_selective_bool
+ { \bool_set_true:N \exp_not:N \l_@@_selective_bool }
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl
+ { \exp_not:o \l_@@_relative_tl }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \keys_set_exclude_groups:nnnN, \keys_set_exclude_groups:nnVN,
+% \keys_set_exclude_groups:nnvN, \keys_set_exclude_groups:nnoN
+% }
+% \begin{macro}
+% {
+% \keys_set_exclude_groups:nnnnN, \keys_set_exclude_groups:nnVnN,
+% \keys_set_exclude_groups:nnvnN, \keys_set_exclude_groups:nnonN
+% }
+% \begin{macro}{\@@_set_exclude_groups:nnnnnN}
+% \begin{macro}
+% {
+% \keys_set_exclude_groups:nnn, \keys_set_exclude_groups:nnV,
+% \keys_set_exclude_groups:nnv, \keys_set_exclude_groups:nno
+% }
+% \begin{macro}{\@@_set_exclude_groups:nnnn}
+% \begin{macro}
+% {
+% \keys_set_groups:nnn, \keys_set_groups:nnV, \keys_set_groups:nnv,
+% \keys_set_groups:nno
+% }
+% \begin{macro}{\@@_set_selective:nnn}
+% \begin{macro}{\@@_set_selective:nnnn}
+% The idea of setting keys in a selective manner again uses booleans
+% wrapped around the basic code. The comments on \cs{keys_set_known:nnN}
+% also apply here. We have a bit more shuffling to do to keep everything
+% nestable.
+% \begin{macrocode}
+\cs_new_protected:Npn \keys_set_exclude_groups:nnnN #1#2#3#4
+ {
+ \exp_args:No \@@_set_exclude_groups:nnnnnN
+ \l_@@_unused_clist
+ \q_@@_no_value {#1} {#2} {#3} #4
+ }
+\cs_generate_variant:Nn \keys_set_exclude_groups:nnnN { nnV , nnv , nno }
+\cs_new_protected:Npn \keys_set_exclude_groups:nnnnN #1#2#3#4#5
+ {
+ \exp_args:No \@@_set_exclude_groups:nnnnnN
+ \l_@@_unused_clist {#4} {#1} {#2} {#3} #5
+ }
+\cs_generate_variant:Nn \keys_set_exclude_groups:nnnnN { nnV , nnv , nno }
+\cs_new_protected:Npn \@@_set_exclude_groups:nnnnnN #1#2#3#4#5#6
+ {
+ \clist_clear:N \l_@@_unused_clist
+ \@@_set_exclude_groups:nnnn {#2} {#3} {#4} {#5}
+ \__kernel_tl_set:Nx #6 { \exp_not:o \l_@@_unused_clist }
+ \__kernel_tl_set:Nx \l_@@_unused_clist { \exp_not:n {#1} }
+ }
+\cs_new_protected:Npn \keys_set_exclude_groups:nnn #1#2#3
+ {\@@_set_exclude_groups:nnnn \q_@@_no_value {#1} {#2} {#3} }
+\cs_generate_variant:Nn \keys_set_exclude_groups:nnn { nnV , nnv , nno }
+\cs_new_protected:Npn \@@_set_exclude_groups:nnnn #1#2#3#4
+ {
+ \use:e
+ {
+ \bool_set_false:N \exp_not:N \l_@@_only_known_bool
+ \bool_set_true:N \exp_not:N \l_@@_filtered_bool
+ \bool_set_true:N \exp_not:N \l_@@_selective_bool
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl { \exp_not:n {#1} }
+ \@@_set_selective:nnn \exp_not:n { {#2} {#3} {#4} }
+ \bool_if:NT \l_@@_only_known_bool
+ { \bool_set_true:N \exp_not:N \l_@@_only_known_bool }
+ \bool_if:NF \l_@@_filtered_bool
+ { \bool_set_false:N \exp_not:N \l_@@_filtered_bool }
+ \bool_if:NF \l_@@_selective_bool
+ { \bool_set_false:N \exp_not:N \l_@@_selective_bool }
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl
+ { \exp_not:o \l_@@_relative_tl }
+ }
+ }
+\cs_new_protected:Npn \keys_set_groups:nnn #1#2#3
+ {
+ \use:e
+ {
+ \bool_set_false:N \exp_not:N \l_@@_only_known_bool
+ \bool_set_false:N \exp_not:N \l_@@_filtered_bool
+ \bool_set_true:N \exp_not:N \l_@@_selective_bool
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl
+ { \exp_not:N \q_@@_no_value }
+ \@@_set_selective:nnn \exp_not:n { {#1} {#2} {#3} }
+ \bool_if:NT \l_@@_only_known_bool
+ { \bool_set_true:N \exp_not:N \l_@@_only_known_bool }
+ \bool_if:NF \l_@@_filtered_bool
+ { \bool_set_true:N \exp_not:N \l_@@_filtered_bool }
+ \bool_if:NF \l_@@_selective_bool
+ { \bool_set_false:N \exp_not:N \l_@@_selective_bool }
+ \tl_set:Nn \exp_not:N \l_@@_relative_tl
+ { \exp_not:o \l_@@_relative_tl }
+ }
+ }
+\cs_generate_variant:Nn \keys_set_groups:nnn { nnV , nnv , nno }
+\cs_new_protected:Npn \@@_set_selective:nnn
+ { \exp_args:No \@@_set_selective:nnnn \l_@@_selective_seq }
+\cs_new_protected:Npn \@@_set_selective:nnnn #1#2#3#4
+ {
+ \exp_args:NNe \seq_set_from_clist:Nn
+ \l_@@_selective_seq { \tl_to_str:n {#3} }
+ \@@_set:nn {#2} {#4}
+ \tl_set:Nn \l_@@_selective_seq {#1}
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\keys_precompile:nnN}
+% A simple wrapper.
+% \begin{macrocode}
+\cs_new_protected:Npn \keys_precompile:nnN #1#2#3
+ {
+ \bool_set_true:N \l_@@_precompile_bool
+ \tl_clear:N \l_@@_precompile_tl
+ \keys_set:nn {#1} {#2}
+ \bool_set_false:N \l_@@_precompile_bool
+ \tl_set_eq:NN #3 \l_@@_precompile_tl
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_set_keyval:n, \@@_set_keyval:nn}
+% \begin{macro}{\@@_set_keyval:nnn, \@@_set_keyval:onn}
+% \begin{macro}{\@@_find_key_module:wNN}
+% \begin{macro}
+% {
+% \@@_find_key_module_auxi:Nw ,
+% \@@_find_key_module_auxii:Nw ,
+% \@@_find_key_module_auxiii:Nn ,
+% \@@_find_key_module_auxiv:Nw
+% }
+% \begin{macro}{\@@_set_selective:}
+% A shared system once again. First, set the current path and add a
+% default if needed. There are then checks to see if a value is
+% required or forbidden. If everything passes, move on to execute the
+% code.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_set_keyval:n #1
+ {
+ \bool_set_true:N \l_@@_no_value_bool
+ \@@_set_keyval:onn \l_@@_module_str {#1} { }
+ }
+\cs_new_protected:Npn \@@_set_keyval:nn #1#2
+ {
+ \bool_set_false:N \l_@@_no_value_bool
+ \@@_set_keyval:onn \l_@@_module_str {#1} {#2}
+ }
+% \end{macrocode}
+% The key path here can be fully defined, after which there is a search
+% for the key and module names: the user may have passed them with part
+% of what is actually the module (for our purposes) in the key name. As
+% that happens on a per-key basis, we use the stack approach to restore
+% the module name without a group.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_set_keyval:nnn #1#2#3
+ {
+ \__kernel_tl_set:Nx \l_keys_path_str
+ {
+ \tl_if_blank:nF {#1}
+ { #1 / }
+ \@@_trim_spaces:n {#2}
+ }
+ \str_clear:N \l_@@_module_str
+ \str_clear:N \l_@@_inherit_str
+ \exp_after:wN \@@_find_key_module:wNN \l_keys_path_str \s_@@_stop
+ \l_@@_module_str \l_keys_key_str
+ \tl_set_eq:NN \l_keys_key_tl \l_keys_key_str
+ \@@_value_or_default:n {#3}
+ \bool_if:NTF \l_@@_selective_bool
+ \@@_set_selective:
+ \@@_execute:
+ \str_set:Nn \l_@@_module_str {#1}
+ }
+\cs_generate_variant:Nn \@@_set_keyval:nnn { o }
+% \end{macrocode}
+% This function uses \cs{cs_set_nopar:Npe} internally for performance reasons,
+% the argument |#1| is already a string in every usage, so turning it into a
+% string again seems unnecessary.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_find_key_module:wNN #1 \s_@@_stop #2 #3
+ {
+ \@@_find_key_module_auxi:Nw #2 #1 \s_@@_nil \@@_find_key_module_auxii:Nw
+ / \s_@@_nil \@@_find_key_module_auxiv:Nw #3
+ }
+\cs_new_protected:Npn \@@_find_key_module_auxi:Nw #1 #2 / #3 \s_@@_nil #4
+ {
+ #4 #1 #2 \s_@@_mark #3 \s_@@_nil #4
+ }
+\cs_new_protected:Npn \@@_find_key_module_auxii:Nw
+ #1 #2 \s_@@_mark #3 \s_@@_nil \@@_find_key_module_auxii:Nw
+ {
+ \cs_set_nopar:Npe #1 { \tl_if_empty:NF #1 { #1 / } #2 }
+ \@@_find_key_module_auxi:Nw #1 #3 \s_@@_nil \@@_find_key_module_auxiii:Nw
+ }
+\cs_new_protected:Npn \@@_find_key_module_auxiii:Nw #1 #2 \s_@@_mark
+ {
+ \cs_set_nopar:Npe #1 { \tl_if_empty:NF #1 { #1 / } #2 }
+ \@@_find_key_module_auxi:Nw #1
+ }
+\cs_new_protected:Npn \@@_find_key_module_auxiv:Nw
+ #1 #2 \s_@@_nil #3 \s_@@_mark
+ \s_@@_nil \@@_find_key_module_auxiv:Nw #4
+ {
+ \cs_set_nopar:Npn #4 { #2 }
+ }
+% \end{macrocode}
+% If selective setting is active, there are a number of possible sub-cases
+% to consider. The key name may not be known at all or if it is, it may not
+% have any groups assigned. There is then the question of whether the
+% selection is opt-in or opt-out.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_set_selective:
+ {
+ \cs_if_exist:cTF { \c_@@_groups_root_str \l_keys_path_str }
+ {
+ \clist_set_eq:Nc \l_@@_groups_clist
+ { \c_@@_groups_root_str \l_keys_path_str }
+ \@@_check_groups:
+ }
+ {
+ \bool_if:NTF \l_@@_filtered_bool
+ \@@_execute:
+ \@@_store_unused:
+ }
+ }
+% \end{macrocode}
+% In the case where selective setting requires a comparison of the list
+% of groups which apply to a key with the list of those which have been
+% set active. That requires two mappings, and again a different outcome
+% depending on whether opt-in or opt-out is set.
+% It is safe to use \cs{clist_if_in:NnTF} because
+% both \cs{l_@@_selective_seq} and \cs{l_@@_groups_clist} contain the
+% groups as strings, without leading/trailing spaces in any item,
+% since the \pkg{l3clist} functions were applied to the result of
+% applying \cs{tl_to_str:n}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_check_groups:
+ {
+ \bool_set_false:N \l_@@_tmp_bool
+ \seq_map_inline:Nn \l_@@_selective_seq
+ {
+ \clist_if_in:NnT \l_@@_groups_clist {##1}
+ {
+ \bool_set_true:N \l_@@_tmp_bool
+ \seq_map_break:
+ }
+ }
+ \bool_if:NTF \l_@@_tmp_bool
+ {
+ \bool_if:NTF \l_@@_filtered_bool
+ \@@_store_unused:
+ \@@_execute:
+ }
+ {
+ \bool_if:NTF \l_@@_filtered_bool
+ \@@_execute:
+ \@@_store_unused:
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_value_or_default:n}
+% \begin{macro}{\@@_default_inherit:}
+% If a value is given, return it as |#1|, otherwise send a default if
+% available.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_value_or_default:n #1
+ {
+ \bool_if:NTF \l_@@_no_value_bool
+ {
+ \cs_if_exist:cTF { \c_@@_default_root_str \l_keys_path_str }
+ {
+ \tl_set_eq:Nc
+ \l_keys_value_tl
+ { \c_@@_default_root_str \l_keys_path_str }
+ }
+ {
+ \tl_clear:N \l_keys_value_tl
+ \cs_if_exist:cT
+ { \c_@@_inherit_root_str \@@_parent:o \l_keys_path_str }
+ { \@@_default_inherit: }
+ }
+ }
+ { \tl_set:Nn \l_keys_value_tl {#1} }
+ }
+\cs_new_protected:Npn \@@_default_inherit:
+ {
+ \clist_map_inline:cn
+ { \c_@@_inherit_root_str \@@_parent:o \l_keys_path_str }
+ {
+ \cs_if_exist:cT
+ { \c_@@_default_root_str ##1 / \l_keys_key_str }
+ {
+ \tl_set_eq:Nc
+ \l_keys_value_tl
+ { \c_@@_default_root_str ##1 / \l_keys_key_str }
+ \clist_map_break:
+ }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_execute:, \@@_execute_inherit:, \@@_execute_unknown:}
+% \begin{macro}[EXP]{\@@_execute:nn, \@@_execute:no}
+% \begin{macro}{\@@_store_unused:,\@@_store_unused_aux:}
+% Actually executing a key is done in two parts. First, look for the
+% key itself, then look for the \texttt{unknown} key with the same
+% path. If both of these fail, complain. What exactly happens if a key
+% is unknown depends on whether unknown keys are being skipped or if
+% an error should be raised.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_execute:
+ {
+ \cs_if_exist:cTF { \c_@@_code_root_str \l_keys_path_str }
+ {
+ \cs_if_exist_use:c { \c_@@_check_root_str \l_keys_path_str }
+ \@@_execute:no \l_keys_path_str \l_keys_value_tl
+ }
+ {
+ \cs_if_exist:cTF
+ { \c_@@_inherit_root_str \@@_parent:o \l_keys_path_str }
+ { \@@_execute_inherit: }
+ { \@@_execute_unknown: }
+ }
+ }
+% \end{macrocode}
+% To deal with the case where there is no hit, we leave
+% \cs{@@_execute_unknown:} in the input stream and clean it up using the
+% break function: that avoids needing a boolean.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_execute_inherit:
+ {
+ \clist_map_inline:cn
+ { \c_@@_inherit_root_str \@@_parent:o \l_keys_path_str }
+ {
+ \cs_if_exist:cT
+ { \c_@@_code_root_str ##1 / \l_keys_key_str }
+ {
+ \str_set:Nn \l_@@_inherit_str {##1}
+ \cs_if_exist_use:c { \c_@@_check_root_str ##1 / \l_keys_key_str }
+ \@@_execute:no { ##1 / \l_keys_key_str } \l_keys_value_tl
+ \clist_map_break:n \use_none:n
+ }
+ }
+ \@@_execute_unknown:
+ }
+\cs_new_protected:Npn \@@_execute_unknown:
+ {
+ \bool_if:NTF \l_@@_only_known_bool
+ { \@@_store_unused: }
+ {
+ \cs_if_exist:cTF
+ { \c_@@_code_root_str \l_@@_module_str / unknown }
+ {
+ \bool_if:NT \l_@@_no_value_bool
+ {
+ \cs_if_exist:cT
+ { \c_@@_default_root_str \l_@@_module_str / unknown }
+ {
+ \tl_set_eq:Nc
+ \l_keys_value_tl
+ { \c_@@_default_root_str \l_@@_module_str / unknown }
+ }
+ }
+ \@@_execute:no { \l_@@_module_str / unknown } \l_keys_value_tl
+ }
+ {
+ \msg_error:nnee { keys } { unknown }
+ \l_keys_path_str \l_@@_module_str
+ }
+ }
+ }
+% \end{macrocode}
+% A key's code is in the control sequence with csname
+% \cs{c_@@_code_root_str} |#1|. We expand it once to get the
+% replacement text (with argument |#2|) and call \cs{use:n}
+% with this replacement as its argument. This ensures that any
+% undefined control sequence error in the key's code will lead to an
+% error message of the form |<argument>|\ldots{}\meta{control
+% sequence} in which one can read the (undefined) \meta{control
+% sequence} in full, rather than an error message that starts with the
+% potentially very long key name, which would make the (undefined)
+% \meta{control sequence} be truncated or sometimes completely hidden.
+% See \url{https://github.com/latex3/latex2e/issues/351}.
+% \begin{macrocode}
+\cs_new:Npn \@@_execute:nn #1#2
+ { \@@_execute:no {#1} { \prg_do_nothing: #2 } }
+\cs_new:Npn \@@_execute:no #1#2
+ {
+ \exp_args:NNo \exp_args:No \use:n
+ {
+ \cs:w \c_@@_code_root_str #1 \exp_after:wN \cs_end:
+ \exp_after:wN {#2}
+ }
+ }
+% \end{macrocode}
+% When there is no relative path, things here are easy: just save the key
+% name and value. When we are working with a relative path, first we
+% need to turn it into a string: that can't happen earlier as we need
+% to store \cs{q_@@_no_value}. Then, use a standard delimited approach to fish
+% out the partial path.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_store_unused:
+ {
+ \@@_quark_if_no_value:NTF \l_@@_relative_tl
+ {
+ \clist_put_right:Ne \l_@@_unused_clist
+ {
+ \l_keys_key_str
+ \bool_if:NF \l_@@_no_value_bool
+ { = { \exp_not:o \l_keys_value_tl } }
+ }
+ }
+ {
+ \tl_if_empty:NTF \l_@@_relative_tl
+ {
+ \clist_put_right:Ne \l_@@_unused_clist
+ {
+ \l_keys_path_str
+ \bool_if:NF \l_@@_no_value_bool
+ { = { \exp_not:o \l_keys_value_tl } }
+ }
+ }
+ { \@@_store_unused_aux: }
+ }
+ }
+\cs_new_protected:Npn \@@_store_unused_aux:
+ {
+ \__kernel_tl_set:Nx \l_@@_relative_tl
+ { \exp_args:No \@@_trim_spaces:n \l_@@_relative_tl }
+ \use:e
+ {
+ \cs_set_protected:Npn \@@_store_unused:w
+ ##1 \l_@@_relative_tl /
+ ##2 \l_@@_relative_tl /
+ ##3 \s_@@_stop
+ }
+ {
+ \tl_if_blank:nF {##1}
+ {
+ \msg_error:nnee { keys } { bad-relative-key-path }
+ \l_keys_path_str
+ \l_@@_relative_tl
+ }
+ \clist_put_right:Ne \l_@@_unused_clist
+ {
+ \exp_not:n {##2}
+ \bool_if:NF \l_@@_no_value_bool
+ { = { \exp_not:o \l_keys_value_tl } }
+ }
+ }
+ \use:e
+ {
+ \@@_store_unused:w \l_keys_path_str
+ \l_@@_relative_tl / \l_@@_relative_tl /
+ \s_@@_stop
+ }
+ }
+\cs_new_protected:Npn \@@_store_unused:w { }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_choice_find:n}
+% \begin{macro}[EXP]{\@@_choice_find:nn}
+% \begin{macro}[EXP]{\@@_multichoice_find:n}
+% Executing a choice has two parts. First, try the choice given, then
+% if that fails call the unknown key. That always exists, as it is created
+% when a choice is first made. So there is no need for any escape code.
+% For multiple choices, the same code ends up used in a mapping.
+% \begin{macrocode}
+\cs_new:Npn \@@_choice_find:n #1
+ {
+ \str_if_empty:NTF \l_@@_inherit_str
+ { \@@_choice_find:nn \l_keys_path_str {#1} }
+ {
+ \@@_choice_find:nn
+ { \l_@@_inherit_str / \l_keys_key_str } {#1}
+ }
+ }
+\cs_new:Npn \@@_choice_find:nn #1#2
+ {
+ \cs_if_exist:cTF { \c_@@_code_root_str #1 / \@@_trim_spaces:n {#2} }
+ { \@@_execute:nn { #1 / \@@_trim_spaces:n {#2} } {#2} }
+ { \@@_execute:nn { #1 / unknown } {#2} }
+ }
+\cs_new:Npn \@@_multichoice_find:n #1
+ { \clist_map_function:nN {#1} \@@_choice_find:n }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Utilities}
+%
+% \begin{macro}[EXP]{\@@_parent:o}
+% \begin{macro}[EXP]
+% {
+% \@@_parent_auxi:w ,
+% \@@_parent_auxii:w ,
+% \@@_parent_auxiii:n ,
+% \@@_parent_auxiv:w
+% }
+% Used to strip off the ending part of the key path after the last~|/|.
+% \begin{macrocode}
+\cs_new:Npn \@@_parent:o #1
+ {
+ \exp_after:wN \@@_parent_auxi:w #1 \q_nil \@@_parent_auxii:w
+ / \q_nil \@@_parent_auxiv:w
+ }
+\cs_new:Npn \@@_parent_auxi:w #1 / #2 \q_nil #3
+ {
+ #3 { #1 } #2 \q_nil #3
+ }
+\cs_new:Npn \@@_parent_auxii:w #1 #2 \q_nil \@@_parent_auxii:w
+ {
+ #1 \@@_parent_auxi:w #2 \q_nil \@@_parent_auxiii:n
+ }
+\cs_new:Npn \@@_parent_auxiii:n #1
+ {
+ / #1 \@@_parent_auxi:w
+ }
+\cs_new:Npn \@@_parent_auxiv:w #1 \q_nil \@@_parent_auxiv:w
+ {
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_trim_spaces:n}
+% \begin{macro}[EXP]
+% {
+% \@@_trim_spaces_auxi:w ,
+% \@@_trim_spaces_auxii:w ,
+% \@@_trim_spaces_auxiii:w
+% }
+% Space stripping has to allow for the fact that the key here might have
+% several parts, and spaces need to be stripped from each part. Since the key
+% name is turned into a string groups can't be stripped accidentally and the
+% precautions of \cs{tl_trim_spaces:n} aren't necessary, in this case it is
+% much faster to just directly strip spaces around |/|.
+% \begin{macrocode}
+\group_begin:
+ \cs_set:Npn \@@_tmp:w #1
+ {
+ \cs_new:Npn \@@_trim_spaces:n ##1
+ {
+ \exp_after:wN \@@_trim_spaces_auxi:w \tl_to_str:n { / ##1 } /
+ \s_@@_nil \@@_trim_spaces_auxi:w
+ \s_@@_mark \@@_trim_spaces_auxii:w
+ #1 / #1
+ \s_@@_nil \@@_trim_spaces_auxii:w
+ \s_@@_mark \@@_trim_spaces_auxiii:w
+ }
+ }
+ \@@_tmp:w { ~ }
+\group_end:
+\cs_new:Npn \@@_trim_spaces_auxi:w #1 ~ / #2 \s_@@_nil #3
+ {
+ #3 #1 / #2 \s_@@_nil #3
+ }
+\cs_new:Npn \@@_trim_spaces_auxii:w #1 / ~ #2 \s_@@_mark #3
+ {
+ #3 #1 / #2 \s_@@_mark #3
+ }
+\cs_new:Npn \@@_trim_spaces_auxiii:w
+ / #1 /
+ \s_@@_nil \@@_trim_spaces_auxi:w
+ \s_@@_mark \@@_trim_spaces_auxii:w
+ /
+ \s_@@_nil \@@_trim_spaces_auxii:w
+ \s_@@_mark \@@_trim_spaces_auxiii:w
+ {
+ #1
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP,pTF]{\keys_if_exist:nn}
+% A utility for others to see if a key exists.
+% \begin{macrocode}
+\prg_new_conditional:Npnn \keys_if_exist:nn #1#2 { p , T , F , TF }
+ {
+ \cs_if_exist:cTF
+ { \c_@@_code_root_str \@@_trim_spaces:n { #1 / #2 } }
+ { \prg_return_true: }
+ { \prg_return_false: }
+ }
+\prg_generate_conditional_variant:Nnn \keys_if_exist:nn { ne } { p , T , F , TF }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP,pTF]{\keys_if_choice_exist:nnn}
+% Just an alternative view on \cs{keys_if_exist:nnTF}.
+% \begin{macrocode}
+\prg_new_conditional:Npnn \keys_if_choice_exist:nnn #1#2#3
+ { p , T , F , TF }
+ {
+ \cs_if_exist:cTF
+ { \c_@@_code_root_str \@@_trim_spaces:n { #1 / #2 / #3 } }
+ { \prg_return_true: }
+ { \prg_return_false: }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\keys_show:nn, \keys_log:nn}
+% \begin{macro}{\@@_show:Nnn}
+% \begin{macro}{\@@_show:n}
+% \begin{macro}{\@@_show:w}
+% \begin{macro}{\@@_show:Nw}
+% To show a key, show its code using a message.
+% \begin{macrocode}
+\cs_new_protected:Npn \keys_show:nn
+ { \@@_show:Nnn \msg_show:nneeee }
+\cs_new_protected:Npn \keys_log:nn
+ { \@@_show:Nnn \msg_log:nneeee }
+\cs_new_protected:Npn \@@_show:Nnn #1#2#3
+ {
+ #1 { keys } { show-key }
+ { \@@_trim_spaces:n { #2 / #3 } }
+ {
+ \keys_if_exist:nnT {#2} {#3}
+ {
+ \exp_args:Nnf \msg_show_item_unbraced:nn { code }
+ {
+ \exp_args:Ne \@@_show:n
+ {
+ \exp_args:Nc \cs_replacement_spec:N
+ {
+ \c_@@_code_root_str
+ \@@_trim_spaces:n { #2 / #3 }
+ }
+ }
+ }
+ }
+ }
+ { } { }
+ }
+\cs_new:Npe \@@_show:n #1
+ {
+ \exp_not:N \@@_show:w
+ #1
+ \tl_to_str:n { \@@_precompile:n }
+ #1
+ \tl_to_str:n { \@@_precompile:n }
+ \exp_not:N \s_@@_stop
+ }
+\use:e
+ {
+ \cs_new:Npn \exp_not:N \@@_show:w
+ #1 \tl_to_str:n { \@@_precompile:n }
+ #2 \tl_to_str:n { \@@_precompile:n }
+ #3 \exp_not:N \s_@@_stop
+ }
+ {
+ \tl_if_blank:nTF {#2}
+ {#1}
+ { \@@_show:Nw #2 \s_@@_stop }
+ }
+\use:e
+ {
+ \cs_new:Npn \exp_not:N \@@_show:Nw #1#2
+ \c_right_brace_str \exp_not:N \s_@@_stop
+ }
+ {#2}
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Messages}
+%
+% For when there is a need to complain.
+% \begin{macrocode}
+\msg_new:nnnn { keys } { bad-relative-key-path }
+ { The~key~'#1'~is~not~inside~the~'#2'~path. }
+ { The~key~'#1'~cannot~be~expressed~relative~to~path~'#2'. }
+\msg_new:nnnn { keys } { boolean-values-only }
+ { Key~'#1'~accepts~boolean~values~only. }
+ { The~key~'#1'~only~accepts~the~values~'true'~and~'false'. }
+\msg_new:nnnn { keys } { choice-unknown }
+ { Key~'#1'~accepts~only~a~fixed~set~of~choices. }
+ {
+ The~key~'#1'~only~accepts~predefined~values,~
+ and~'#2'~is~not~one~of~these.
+ }
+\msg_new:nnnn { keys } { unknown }
+ { The~key~'#1'~is~unknown~and~is~being~ignored. }
+ {
+ The~module~'#2'~does~not~have~a~key~called~'#1'.\\
+ Check~that~you~have~spelled~the~key~name~correctly.
+ }
+\msg_new:nnnn { keys } { nested-choice-key }
+ { Attempt~to~define~'#1'~as~a~nested~choice~key. }
+ {
+ The~key~'#1'~cannot~be~defined~as~a~choice~as~the~parent~key~'#2'~is~
+ itself~a~choice.
+ }
+\msg_new:nnnn { keys } { value-forbidden }
+ { The~key~'#1'~does~not~take~a~value. }
+ {
+ The~key~'#1'~should~be~given~without~a~value.\\
+ The~value~'#2'~was~present:~the~key~will~be~ignored.
+ }
+\msg_new:nnnn { keys } { value-required }
+ { The~key~'#1'~requires~a~value. }
+ {
+ The~key~'#1'~must~have~a~value.\\
+ No~value~was~present:~the~key~will~be~ignored.
+ }
+\msg_new:nnn { keys } { show-key }
+ {
+ The~key~#1~
+ \tl_if_empty:nTF {#2}
+ { is~undefined. }
+ { has~the~properties: #2 . }
+ }
+\prop_gput:Nnn \g_msg_module_name_prop { keys } { LaTeX }
+\prop_gput:Nnn \g_msg_module_type_prop { keys } { }
+% \end{macrocode}
+%
+% \begin{macrocode}
+%</package>
+% \end{macrocode}
+%
+%\end{implementation}
+%
+%\PrintIndex