% SPDX-License-Identifier: MIT
% Copyright (c) 2026 import-citation-cff contributors
% Supports TeX Live 2025 and later; 2024-11-01 is the LaTeX release that
% TeX Live 2025 shipped with. CI tests TeX Live 2025 and 2026.
\NeedsTeXFormat{LaTeX2e}[2024-11-01]
\ProvidesExplPackage{import-citation-cff}{2026-11-08}{0.3.0}
  {Import Citation File Format metadata into LaTeX}
\RequirePackage{lt3luabridge}
\tl_const:Ne \c__cfflatex_package_path_tl { \@currpath }

% check (default true): warn unless the title page uses the fields of the
% citation that the author style of the document checks, by default the title
% and every author in \maketitle. See "Checking the title page".
% style: the author style of the document. \cffsetauthors uses it by default,
% and the check uses its check-fields and check-region keys.
\bool_new:N \g__cfflatex_check_bool
\tl_new:N \g__cfflatex_document_style_tl
\keys_define:nn { import-citation-cff }
  {
    check .bool_gset:N = \g__cfflatex_check_bool,
    check .initial:n = true,
    style .tl_gset:N = \g__cfflatex_document_style_tl,
    style .value_required:n = true,
  }
\ProcessKeyOptions [import-citation-cff]

\msg_new:nnn { import-citation-cff } { missing-file }
  { CFF~file~'#1'~was~not~found. }
\msg_new:nnn { import-citation-cff } { missing-helper }
  { Install~cfflatex.lua~alongside~import-citation-cff.sty. }
\msg_new:nnn { import-citation-cff } { invalid } { Cannot~read~CFF~file:~#1. }
\msg_new:nnn { import-citation-cff } { not-loaded }
  { Call~\iow_char:N\\includecff~first. }
\msg_new:nnn { import-citation-cff } { author-index }
  { Author~index~'#1'~is~out~of~range. }
\msg_new:nnn { import-citation-cff } { affiliation-index }
  { Affiliation~'#1'~is~out~of~range. }
\msg_new:nnn { import-citation-cff } { not-a-value } { Not~a~value:~#1. }
\msg_new:nnn { import-citation-cff } { not-a-list } { Not~a~list:~#1. }
\msg_new:nnn { import-citation-cff } { contact-index }
  { Contact~'#1'~is~out~of~range. }
\msg_new:nnn { import-citation-cff } { not-in-contact-loop }
  { Not~inside~\iow_char:N\\cffforeachcontact. }
\msg_new:nnn { import-citation-cff } { not-in-loop }
  { Not~inside~\iow_char:N\\cffforeachauthor. }
\msg_new:nnn { import-citation-cff } { not-in-affiliation-loop }
  { Not~inside~an~affiliation~loop. }
\msg_new:nnn { import-citation-cff } { not-in-author-affiliation-loop }
  { Not~in~an~author~affiliation~loop. }
\msg_new:nnn { import-citation-cff } { title-unused }
  {
    \iow_char:N\\title~does~not~use~the~title~of~the~citation.~
    Load~import-citation-cff~with~check=false~to~skip~this~check.
  }
\msg_new:nnn { import-citation-cff } { authors-unused }
  {
    \iow_char:N\\author~does~not~use~author(s)~#1~of~the~citation.~
    Load~import-citation-cff~with~check=false~to~skip~this~check.
  }
\msg_new:nnn { import-citation-cff } { field-unused }
  {
    The~title~page~does~not~use~'#1'~of~the~citation.~
    Load~import-citation-cff~with~check=false~to~skip~this~check.
  }
\msg_new:nnn { import-citation-cff } { region-authors-unused }
  {
    The~title~page~does~not~use~author(s)~#1~of~the~citation.~
    Load~import-citation-cff~with~check=false~to~skip~this~check.
  }
\msg_new:nnn { import-citation-cff } { check-fallback }
  {
    No~check~region~of~author~style~'#1'~was~found;~
    the~whole~document~was~checked.
  }
\msg_new:nnn { import-citation-cff } { check-region }
  { Invalid~check~region~'#1'. }
\msg_new:nnn { import-citation-cff } { style-only-key }
  { The~key~'#1'~is~only~allowed~in~an~author~style~definition. }
\msg_new:nnn { import-citation-cff } { style-package-missing }
  { style=#1~needs~the~#2~package. }
\msg_new:nnn { import-citation-cff } { style-name }
  { Invalid~author~style~name~'#1'. }
\msg_new:nnn { import-citation-cff } { style-duplicate }
  { Author~style~'#1'~is~already~registered. }
\msg_new:nnn { import-citation-cff } { style-missing }
  { Author~style~'#1'~is~not~registered;~cannot~find~cfflatex-style-#1.def. }
\msg_new:nnn { import-citation-cff } { style-not-registered }
  { Author~style~'#1'~was~not~registered~by~its~file. }
\msg_new:nnn { import-citation-cff } { shell-escape }
  {
    pdfLaTeX~requires~unrestricted~shell~escape~to~read~CFF~files.~
    Compile~with~--shell-escape,~or~use~LuaLaTeX.
  }

\prop_new:N \g__cfflatex_values_prop
% Every value of the citation by its path, such as "authors/1/name", and the
% kind of each mapping ("map") and sequence (its length) by its path, for \cff.
\prop_new:N \g__cfflatex_fields_prop
\prop_new:N \g__cfflatex_kinds_prop
\int_new:N \g__cfflatex_author_count_int
% The index of the current author in \cffforeachauthor; 0 outside the loop.
\int_new:N \g__cfflatex_author_index_int
% The number of the current affiliation in \cffforeachaffiliation, and the
% index of the current affiliation of the author in
% \cffforeachauthoraffiliation; 0 outside these loops.
\int_new:N \g__cfflatex_affiliation_index_int
\int_new:N \g__cfflatex_author_affiliation_index_int
% The index of the current contact in \cffforeachcontact; 0 outside the loop.
\int_new:N \g__cfflatex_contact_index_int
\bool_new:N \g__cfflatex_loaded_bool
\tl_new:N \l__cfflatex_source_tl
\tl_new:N \l__cfflatex_filename_tl
\tl_new:N \g__cfflatex_helper_tl
\str_new:N \l__cfflatex_file_lua_str
\str_new:N \l__cfflatex_helper_lua_str
\str_new:N \l__cfflatex_source_lua_str
\ior_new:N \g__cfflatex_dependency_ior
% For the check: whether a check region is open, the part of the title page
% being typeset (1: \title, 2: \author, 0: neither), the uses recorded as
% "<region>/<part>/<use>" and "<region>/*/<use>", and missing authors. <use>
% is <i> for author <i>, and the negative number of another checked field.
\bool_new:N \g__cfflatex_recording_bool
\tl_new:N \g__cfflatex_part_tl
\prop_new:N \g__cfflatex_used_prop
\clist_new:N \l__cfflatex_missing_clist
% The check of the document: the author style that gives it, the fields it
% checks and their numbers, its regions (maketitle and hooks<n>) and whether
% the whole document is the fallback region, the open regions, and whether a
% region has been checked.
\tl_new:N \g__cfflatex_check_style_tl
\clist_new:N \g__cfflatex_check_fields_clist
\prop_new:N \g__cfflatex_check_ids_prop
\seq_new:N \g__cfflatex_check_regions_seq
\bool_new:N \g__cfflatex_check_document_bool
\clist_new:N \g__cfflatex_check_open_clist
\bool_new:N \g__cfflatex_check_done_bool
\cs_generate_variant:Nn \ior_open:Nn { NV }

% Prefer the helper next to this package so both files share a version.
\file_get_full_name:nNF { \@currpath cfflatex.lua } \g__cfflatex_helper_tl
  {
    \file_get_full_name:nNF { cfflatex.lua } \g__cfflatex_helper_tl
      { \msg_fatal:nn { import-citation-cff } { missing-helper } }
  }

\keys_define:nn { import-citation-cff / include }
  {
    source .tl_set:N = \l__cfflatex_source_tl,
    source .value_required:n = true,
  }

% Quote a file name or a source key as a Lua string literal; the file contents
% are parsed as YAML and never become Lua source.
\cs_new_protected:Npn \__cfflatex_lua_quote:NN #1#2
  {
    \str_set:Ne #2 { \tl_to_str:V #1 }
    \regex_replace_all:nnN { [\\"] } { \\\0 } #2
    \regex_replace_all:nnN { \r } { \\r } #2
    \regex_replace_all:nnN { \n } { \\n } #2
    \str_put_left:Nn #2 { " }
    \str_put_right:Nn #2 { " }
  }

% Called by the TeX code that cfflatex.lua returns; explcheck cannot see these
% uses, so it would report the functions as unused (W401).
\cs_new_protected:Npn \__cfflatex_store:nn #1#2 % noqa: w401
  { \prop_gput:Nnn \g__cfflatex_values_prop {#1} {#2} }
\cs_new_protected:Npn \__cfflatex_store_field:nn #1#2 % noqa: w401
  { \prop_gput:Nnn \g__cfflatex_fields_prop {#1} {#2} }
\cs_new_protected:Npn \__cfflatex_store_kind:nn #1#2 % noqa: w401
  { \prop_gput:Nnn \g__cfflatex_kinds_prop {#1} {#2} }
\cs_new_protected:Npn \__cfflatex_finish:n #1 % noqa: w401
  {
    \int_gset:Nn \g__cfflatex_author_count_int {#1}
    \bool_gset_true:N \g__cfflatex_loaded_bool
  }
\cs_new_protected:Npn \__cfflatex_fail:n #1 % noqa: w401
  { \msg_fatal:nnn { import-citation-cff } { invalid } {#1} }

% \includecff[source=<key>]{<file>}
% Reads the top level of <file>, or the mapping under its top-level <key>, such
% as preferred-citation. Each call replaces the previously loaded metadata.
\NewDocumentCommand \includecff {O{} m}
  {
    \group_begin:
    \tl_clear:N \l__cfflatex_source_tl
    \keys_set:nn { import-citation-cff / include } {#1}
    \file_get_full_name:nNF {#2} \l__cfflatex_filename_tl
      { \msg_fatal:nnn { import-citation-cff } { missing-file } {#2} }
    \sys_if_engine_luatex:F
      {
        \sys_if_shell_unrestricted:F
          { \msg_fatal:nn { import-citation-cff } { shell-escape } }
      }
    % cfflatex.lua reads the file outside TeX. Opening it once through TeX
    % lists it in the .fls file of the -recorder option, which latexmk and
    % LaTeX Workshop use to rebuild when a dependency changes. Finding the file
    % above does not always do so: LuaLaTeX with shell escape does not record
    % it.
    \ior_open:NV \g__cfflatex_dependency_ior \l__cfflatex_filename_tl
    \ior_close:N \g__cfflatex_dependency_ior
    \bool_gset_false:N \g__cfflatex_loaded_bool
    \int_gzero:N \g__cfflatex_author_count_int
    \prop_gclear:N \g__cfflatex_values_prop
    \prop_gclear:N \g__cfflatex_fields_prop
    \prop_gclear:N \g__cfflatex_kinds_prop
    \__cfflatex_lua_quote:NN \l__cfflatex_filename_tl \l__cfflatex_file_lua_str
    \__cfflatex_lua_quote:NN \g__cfflatex_helper_tl \l__cfflatex_helper_lua_str
    \__cfflatex_lua_quote:NN \l__cfflatex_source_tl \l__cfflatex_source_lua_str
    \luabridge_now:e
      {
        local~kpse = require("kpse");
        local~helper = \exp_not:V \l__cfflatex_helper_lua_str;
        local~cfflatex = assert(loadfile(
        kpse.find_file(helper,~"tex")~or~helper))(helper);
        print(cfflatex.read(
        \exp_not:V \l__cfflatex_file_lua_str,
        \exp_not:V \l__cfflatex_source_lua_str
        ));
      }
    \group_end:
  }

% Checking the title page ----------------------------------------------------
%
% The author style of the document gives the fields to check and the regions
% of the document to check them in (see "Author styles" below). While a region
% is open, \cff and \cffauthor leave a record marker before the values of these
% fields. In the maketitle region, markers around the contents of \@title and
% \@author also tell which part of the title page is being typeset. The
% markers record when they are executed, which is when the title page is
% typeset; this sees uses in loops such as \cffforeachauthor and \foreach, whose
% indices are known only then, and in macros of the document. The markers carry
% only digits and "-", so case changes such as \MakeUppercase keep them intact,
% and their names contain no "_" or ":", so they stay readable if a class
% writes the title page to a file.
%
% The first region that closes is checked, and no region is checked after it.
% If the whole document is the fallback region, it is checked at its end when
% no other region has closed.

% <use> is <i> for author <i>, and the number of another checked field.
\cs_new_protected:cpn { cfflatex@mark } #1
  {
    \bool_if:NT \g__cfflatex_recording_bool
      {
        \clist_map_inline:Nn \g__cfflatex_check_open_clist
          {
            \prop_gput:Nen \g__cfflatex_used_prop
              { ##1 / \g__cfflatex_part_tl / #1 }
              {}
            \prop_gput:Nnn \g__cfflatex_used_prop { ##1 / * / #1 } {}
          }
      }
  }
% <part> is 1 for \title, 2 for \author, and 0 after them.
\cs_new_protected:cpn { cfflatex@part } #1
  { \tl_gset:Nn \g__cfflatex_part_tl {#1} }
\cs_new:Npn \__cfflatex_mark:n #1
  {
    % The marker is protected, so it stays a marker in expansion contexts.
    \bool_if:NT \g__cfflatex_recording_bool
      { \use:c { cfflatex@mark } {#1} }
  }
\cs_generate_variant:Nn \__cfflatex_mark:n { e }
\cs_generate_variant:Nn \prop_gput:Nnn { Nen }
\prg_generate_conditional_variant:Nnn \prop_if_in:Nn { Ne } { F }

% Opens the region #1, unless a region has already been checked.
\cs_new_protected:Npn \__cfflatex_region_begin:n #1
  {
    \bool_if:NF \g__cfflatex_check_done_bool
      {
        \clist_if_in:NnF \g__cfflatex_check_open_clist {#1}
          { \clist_gput_right:Nn \g__cfflatex_check_open_clist {#1} }
        \bool_gset_true:N \g__cfflatex_recording_bool
      }
  }
% Closes the region #1 if it is open, and checks it.
\cs_new_protected:Npn \__cfflatex_region_end:n #1
  {
    \clist_if_in:NnT \g__cfflatex_check_open_clist {#1}
      {
        \bool_gset_true:N \g__cfflatex_check_done_bool
        \bool_gset_false:N \g__cfflatex_recording_bool
        \clist_gclear:N \g__cfflatex_check_open_clist
        \bool_if:NT \g__cfflatex_loaded_bool
          {
            \clist_map_inline:Nn \g__cfflatex_check_fields_clist
              {
                \str_if_eq:nnTF {##1} { authors }
                  { \__cfflatex_check_authors:n {#1} }
                  { \__cfflatex_check_field:nn {#1} {##1} }
              }
          }
      }
  }
% Warns unless the region #1 uses the field #2. A field that the citation does
% not have cannot be used. In \maketitle, \title must use the title.
\cs_new_protected:Npn \__cfflatex_check_field:nn #1#2
  {
    \prop_if_in:NnT \g__cfflatex_fields_prop {#2}
      {
        \bool_lazy_and:nnTF { \str_if_eq_p:nn {#1} { maketitle } }
          { \str_if_eq_p:nn {#2} { title } }
          {
            \prop_if_in:NeF \g__cfflatex_used_prop
              { #1 / 1 / \prop_item:Nn \g__cfflatex_check_ids_prop {#2} }
              { \msg_warning:nn { import-citation-cff } { title-unused } }
          }
          {
            \prop_if_in:NeF \g__cfflatex_used_prop
              { #1 / * / \prop_item:Nn \g__cfflatex_check_ids_prop {#2} }
              { \msg_warning:nnn { import-citation-cff } { field-unused } {#2} }
          }
      }
  }
% Warns unless the region #1 uses every author. In \maketitle, \author must
% use them.
\cs_new_protected:Npn \__cfflatex_check_authors:n #1
  {
    \clist_clear:N \l__cfflatex_missing_clist
    \int_step_inline:nn { \g__cfflatex_author_count_int }
      {
        \prop_if_in:NeF \g__cfflatex_used_prop
          { #1 / \str_if_eq:nnTF {#1} { maketitle } { 2 } { * } / ##1 }
          { \clist_put_right:Nn \l__cfflatex_missing_clist {##1} }
      }
    \clist_if_empty:NF \l__cfflatex_missing_clist
      {
        \str_if_eq:nnTF {#1} { maketitle }
          {
            \msg_warning:nne { import-citation-cff } { authors-unused }
              { \clist_use:Nn \l__cfflatex_missing_clist { ,~ } }
          }
          {
            \msg_warning:nne { import-citation-cff } { region-authors-unused }
              { \clist_use:Nn \l__cfflatex_missing_clist { ,~ } }
          }
      }
  }

\cs_new_protected:Npn \__cfflatex_check_begin:
  {
    \seq_if_in:NnT \g__cfflatex_check_regions_seq { maketitle }
      {
        \bool_lazy_and:nnT { \g__cfflatex_loaded_bool }
          { ! \g__cfflatex_check_done_bool }
          {
            \tl_gset:Nn \g__cfflatex_part_tl { 0 }
            \__cfflatex_wrap_part:Nn \@title { 1 }
            \__cfflatex_wrap_part:Nn \@author { 2 }
            \__cfflatex_region_begin:n { maketitle }
          }
      }
  }
\cs_new_protected:Npn \__cfflatex_wrap_part:Nn #1#2
  {
    \cs_gset:Npe #1
      {
        \exp_not:c { cfflatex@part } {#2}
        \exp_not:o {#1}
        \exp_not:c { cfflatex@part } { 0 }
      }
  }
\AddToHook {cmd/maketitle/before} [import-citation-cff]
  {\__cfflatex_check_begin:}
\AddToHook {cmd/maketitle/after} [import-citation-cff]
  {\__cfflatex_region_end:n { maketitle }}
% The whole document is checked at its end, if no other region was checked.
\cs_new_protected:Npn \__cfflatex_check_fallback:
  {
    \bool_lazy_and:nnT { \g__cfflatex_check_document_bool }
      { ! \g__cfflatex_check_done_bool }
      {
        \bool_lazy_and:nnT { \g__cfflatex_loaded_bool }
          { ! \seq_if_empty_p:N \g__cfflatex_check_regions_seq }
          {
            \msg_info:nne { import-citation-cff } { check-fallback }
              { \tl_use:N \g__cfflatex_check_style_tl }
          }
        \__cfflatex_region_end:n { document }
      }
  }
\AddToHook {enddocument} [import-citation-cff] {\__cfflatex_check_fallback:}
% hyperref drops the markers from PDF strings, such as bookmarks.
\AddToHook {begindocument} [import-citation-cff]
  {
    \cs_if_exist:NT \pdfstringdefDisableCommands
      {
        \pdfstringdefDisableCommands
          {
            \cs_set_eq:cN { cfflatex@mark } \use_none:n
            \cs_set_eq:cN { cfflatex@part } \use_none:n
          }
      }
  }

% Getters --------------------------------------------------------------------

% Expands to the value stored under the key #1, or to nothing if it is absent.
\cs_new:Npn \__cfflatex_value:n #1
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      { \prop_item:Nn \g__cfflatex_values_prop {#1} }
      { \msg_expandable_error:nn { import-citation-cff } { not-loaded } }
  }

% Expands to #2 if a CFF file is loaded and #1 is the index of an author, and
% reports an error otherwise.
\cs_new:Npn \__cfflatex_if_author:nT #1#2
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \bool_lazy_or:nnTF { \int_compare_p:nNn {#1} < { 1 } }
          { \int_compare_p:nNn {#1} > { \g__cfflatex_author_count_int } }
          {
            \msg_expandable_error:nnn { import-citation-cff } { author-index }
              {#1}
          }
          {#2}
      }
      { \msg_expandable_error:nn { import-citation-cff } { not-loaded } }
  }

% \cffauthor{<index>}{<field>} expands to a field of the <index>-th author,
% counting from 1. An absent field expands to nothing.
\cs_generate_variant:Nn \prop_item:Nn { Ne }
\NewExpandableDocumentCommand \cffauthor {m m}
  {
    \__cfflatex_if_author:nT {#1}
      {
        \__cfflatex_mark:e { \int_eval:n {#1} }
        \prop_item:Ne \g__cfflatex_values_prop
          { authors / \int_eval:n {#1} / \tl_to_str:n {#2} }
      }
  }

% Any field ------------------------------------------------------------------
%
% \cff{<path>} expands to the value at <path>, the keys and indices that lead
% to it from the citation, separated by slashes, such as authors/1/name. A
% missing path expands to nothing, and a mapping or a sequence is an error.
% \cffcount{<path>} expands to the length of the sequence at <path>, 0 if it
% is missing; a value or a mapping is an error. \cff{<path>} counts for the
% check as a use of <path>, such as title, and \cff{authors/<i>/<field>} as a
% use of author <i>, like \cffauthor.
% The path is expanded first, so that it may contain \cffauthorindex.
\NewExpandableDocumentCommand \cff {m} {\exp_args:Ne \__cfflatex_cff:n {#1}}
\NewExpandableDocumentCommand \cffcount {m}
  {\exp_args:Ne \__cfflatex_cffcount:n {#1}}
\cs_new:Npn \__cfflatex_cff:n #1
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \prop_if_in:NnTF \g__cfflatex_fields_prop {#1}
          {
            \__cfflatex_path_mark:n {#1}
            \prop_item:Nn \g__cfflatex_fields_prop {#1}
          }
          {
            \prop_if_in:NnT \g__cfflatex_kinds_prop {#1}
              {
                \msg_expandable_error:nnn { import-citation-cff }
                  { not-a-value }
                  {#1}
              }
          }
      }
      { \msg_expandable_error:nn { import-citation-cff } { not-loaded } }
  }
\cs_new:Npn \__cfflatex_cffcount:n #1
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \prop_if_in:NnTF \g__cfflatex_kinds_prop {#1}
          {
            \str_if_eq:eeTF { \prop_item:Nn \g__cfflatex_kinds_prop {#1} }
              { map }
              {
                \msg_expandable_error:nnn { import-citation-cff } { not-a-list }
                  {#1}
              }
              { \prop_item:Nn \g__cfflatex_kinds_prop {#1} }
          }
          {
            \prop_if_in:NnTF \g__cfflatex_fields_prop {#1}
              {
                \msg_expandable_error:nnn { import-citation-cff } { not-a-list }
                  {#1}
              }
              { 0 }
          }
      }
      { \msg_expandable_error:nn { import-citation-cff } { not-loaded } }
  }
% Marks the use of the value at the path #1 for the check: a checked field,
% such as title, or a field of an author.
\cs_new:Npn \__cfflatex_path_mark:n #1
  {
    \prop_if_in:NnTF \g__cfflatex_check_ids_prop {#1}
      { \__cfflatex_mark:e { \prop_item:Nn \g__cfflatex_check_ids_prop {#1} } }
      { \__cfflatex_author_mark:w #1 / / \s__cfflatex_stop }
  }
% The index #2 of an author is a number since the value at #1/#2/#3 exists.
\scan_new:N \s__cfflatex_stop
\cs_new:Npn \__cfflatex_author_mark:w #1 / #2 / #3 \s__cfflatex_stop
  {
    \str_if_eq:nnT {#1} { authors }
      {
        \tl_if_blank:nF {#3}
          { \__cfflatex_mark:e { \int_eval:n {#2} } }
      }
  }

% Affiliations ---------------------------------------------------------------
%
% cfflatex.lua splits each affiliation string at semicolons and numbers the
% distinct affiliations of the citation in the order they first appear.

% Expands to the number stored under the key #1, or to 0 if it is absent.
\prg_generate_conditional_variant:Nnn \prop_if_in:Nn { Ne } { TF }
\cs_new:Npn \__cfflatex_count:n #1
  {
    \prop_if_in:NeTF \g__cfflatex_values_prop {#1}
      { \prop_item:Ne \g__cfflatex_values_prop {#1} }
      { 0 }
  }
% Expands to #3 if #1 is between 1 and #2, and reports an error otherwise.
\cs_new:Npn \__cfflatex_if_affiliation:nnT #1#2#3
  {
    \bool_lazy_or:nnTF { \int_compare_p:nNn {#1} < { 1 } }
      { \int_compare_p:nNn {#1} > {#2} }
      {
        \msg_expandable_error:nnn { import-citation-cff } { affiliation-index }
          {#1}
      }
      {#3}
  }
% Expands to the item of author #1 under "affiliation-#3/#2".
\cs_new:Npn \__cfflatex_author_affiliation:nnn #1#2#3
  {
    \__cfflatex_if_author:nT {#1}
      {
        \__cfflatex_if_affiliation:nnT {#2}
          {
            \__cfflatex_count:n
              { authors / \int_eval:n {#1} / affiliation-count }
          }
          {
            \prop_item:Ne \g__cfflatex_values_prop
              {
                authors / \int_eval:n {#1} / affiliation- #3 / \int_eval:n {#2}
              }
          }
      }
  }

% \cffauthoraffiliationcount{<i>} expands to the number of affiliations of
% author <i>, which is 0 if the author has none.
\NewExpandableDocumentCommand \cffauthoraffiliationcount {m}
  {
    \__cfflatex_if_author:nT {#1}
      { \__cfflatex_count:n { authors / \int_eval:n {#1} / affiliation-count } }
  }

% \cffauthoraffiliation{<i>}{<k>} expands to the <k>-th affiliation of author
% <i>.
\NewExpandableDocumentCommand \cffauthoraffiliation {m m}
  {\__cfflatex_author_affiliation:nnn {#1} {#2} { names }}

% \cffconvertaffiliationindex{<i>}{<k>} expands to the number of the <k>-th
% affiliation of author <i> among the distinct affiliations of the citation,
% the index that \cffforeachaffiliation and \cffaffiliation use.
\NewExpandableDocumentCommand \cffconvertaffiliationindex {m m}
  {\__cfflatex_author_affiliation:nnn {#1} {#2} { indices }}

% \cffaffiliationcount expands to the number of distinct affiliations of the
% citation, and \cffaffiliation{<n>} to the <n>-th of them.
\NewExpandableDocumentCommand \cffaffiliationcount {}
  {\__cfflatex_value:n { affiliation-count }}
\NewExpandableDocumentCommand \cffaffiliation {m}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \__cfflatex_if_affiliation:nnT {#1}
          { \__cfflatex_count:n { affiliation-count } }
          {
            \prop_item:Ne \g__cfflatex_values_prop
              { affiliations / \int_eval:n {#1} }
          }
      }
      { \msg_expandable_error:nn { import-citation-cff } { not-loaded } }
  }

% Contacts -------------------------------------------------------------------
%
% The contacts of the citation are optional; like the authors, each is a person
% or an entity.

% \cffcontact{<index>}{<field>} expands to a field of the <index>-th contact,
% counting from 1. An absent field expands to nothing.
\NewExpandableDocumentCommand \cffcontact {m m}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \bool_lazy_or:nnTF { \int_compare_p:nNn {#1} < { 1 } }
          {
            \int_compare_p:nNn {#1} > { \__cfflatex_count:n { contact-count } }
          }
          {
            \msg_expandable_error:nnn { import-citation-cff } { contact-index }
              {#1}
          }
          {
            \prop_item:Ne \g__cfflatex_values_prop
              { contact / \int_eval:n {#1} / \tl_to_str:n {#2} }
          }
      }
      { \msg_expandable_error:nn { import-citation-cff } { not-loaded } }
  }

% Loops ----------------------------------------------------------------------
%
% \__cfflatex_loop:nnnnn {<first>} {<last>} {<set>} {<code>} {<restore>} runs
% <set>{<value>} and then <code> for each <value> from <first> to <last>, and
% then <restore>. The loops below keep their state in global variables, set by
% <set> and restored by <restore> to that of an enclosing loop, and in the
% arguments of this function. They add no group, so <code> may close and
% reopen groups, as \and does between the authors in \author.
\cs_new_protected:Npn \__cfflatex_loop:nnnnn #1#2#3#4#5
  {
    \int_compare:nNnTF {#1} > {#2}
      {#5}
      {
        #3 {#1}
        #4
        \exp_args:Nf \__cfflatex_loop:nnnnn { \int_eval:n { #1 + 1 } } {#2} {#3}
          {#4}
          {#5}
      }
  }

% \cffforeachauthor{<code>} runs <code> once for each author, in order, with
% \cffauthorindex expanding to the index of the author.
\NewDocumentCommand \cffforeachauthor {+m}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \use:e
          {
            \__cfflatex_loop:nnnnn { 1 }
              { \int_use:N \g__cfflatex_author_count_int }
              { \int_gset:Nn \exp_not:N \g__cfflatex_author_index_int }
              { \exp_not:n {#1} }
              {
                \int_gset:Nn \exp_not:N \g__cfflatex_author_index_int
                  { \int_use:N \g__cfflatex_author_index_int }
              }
          }
      }
      { \msg_error:nn { import-citation-cff } { not-loaded } }
  }

% \cffauthorindex expands to the index of the current author in
% \cffforeachauthor.
\NewExpandableDocumentCommand \cffauthorindex {}
  {
    \int_compare:nNnTF { \g__cfflatex_author_index_int } = { 0 }
      { \msg_expandable_error:nn { import-citation-cff } { not-in-loop } }
      { \int_use:N \g__cfflatex_author_index_int }
  }

% \cffforeachaffiliation{<code>} runs <code> once for each distinct affiliation
% of the citation, in order, with \cffaffiliationindex expanding to the number
% of the affiliation.
\NewDocumentCommand \cffforeachaffiliation {+m}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \use:e
          {
            \__cfflatex_loop:nnnnn { 1 }
              { \__cfflatex_count:n { affiliation-count } }
              { \int_gset:Nn \exp_not:N \g__cfflatex_affiliation_index_int }
              { \exp_not:n {#1} }
              {
                \int_gset:Nn \exp_not:N \g__cfflatex_affiliation_index_int
                  { \int_use:N \g__cfflatex_affiliation_index_int }
              }
          }
      }
      { \msg_error:nn { import-citation-cff } { not-loaded } }
  }

% \cffforeachauthoraffiliation{<index>}{<code>} runs <code> once for each
% affiliation of the <index>-th author, in order, with
% \cffauthoraffiliationindex expanding to the index of the affiliation among
% those of the author, counting from 1.
\NewDocumentCommand \cffforeachauthoraffiliation {m +m}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \bool_lazy_or:nnTF { \int_compare_p:nNn {#1} < { 1 } }
          { \int_compare_p:nNn {#1} > { \g__cfflatex_author_count_int } }
          {
            \msg_error:nne { import-citation-cff } { author-index }
              { \int_eval:n {#1} }
          }
          {
            \exp_args:Ne \__cfflatex_foreach_author_affiliation:nn
              { \int_eval:n {#1} }
              {#2}
          }
      }
      { \msg_error:nn { import-citation-cff } { not-loaded } }
  }
% #1 is the index of the author, and #2 the code.
\cs_new_protected:Npn \__cfflatex_foreach_author_affiliation:nn #1#2
  {
    \use:e
      {
        \__cfflatex_loop:nnnnn { 1 }
          { \__cfflatex_count:n { authors / #1 / affiliation-count } }
          { \int_gset:Nn \exp_not:N \g__cfflatex_author_affiliation_index_int }
          { \exp_not:n {#2} }
          {
            \int_gset:Nn \exp_not:N \g__cfflatex_author_affiliation_index_int
              { \int_use:N \g__cfflatex_author_affiliation_index_int }
          }
      }
  }

% \cffaffiliationindex and \cffauthoraffiliationindex expand to the number of
% the current affiliation in \cffforeachaffiliation and to the index of the
% current affiliation of the author in \cffforeachauthoraffiliation.
% Expands to the value of the counter #1 if it is not 0, and to the code #2,
% an error, otherwise.
\cs_new:Npn \__cfflatex_loop_state:Nn #1#2
  {
    \int_compare:nNnTF {#1} = { 0 }
      {#2}
      { \int_use:N #1 }
  }
% \cffforeachcontact{<code>} runs <code> once for each contact of the citation,
% in order, with \cffcontactindex expanding to the index of the contact.
\NewDocumentCommand \cffforeachcontact {+m}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \use:e
          {
            \__cfflatex_loop:nnnnn { 1 }
              { \__cfflatex_count:n { contact-count } }
              { \int_gset:Nn \exp_not:N \g__cfflatex_contact_index_int }
              { \exp_not:n {#1} }
              {
                \int_gset:Nn \exp_not:N \g__cfflatex_contact_index_int
                  { \int_use:N \g__cfflatex_contact_index_int }
              }
          }
      }
      { \msg_error:nn { import-citation-cff } { not-loaded } }
  }

\NewExpandableDocumentCommand \cffaffiliationindex {}
  {
    \__cfflatex_loop_state:Nn \g__cfflatex_affiliation_index_int
      {
        \msg_expandable_error:nn { import-citation-cff }
          { not-in-affiliation-loop }
      }
  }
\NewExpandableDocumentCommand \cffauthoraffiliationindex {}
  {
    \__cfflatex_loop_state:Nn \g__cfflatex_author_affiliation_index_int
      {
        \msg_expandable_error:nn { import-citation-cff }
          { not-in-author-affiliation-loop }
      }
  }

% \cffcontactindex expands to the index of the current contact in
% \cffforeachcontact.
\NewExpandableDocumentCommand \cffcontactindex {}
  {
    \__cfflatex_loop_state:Nn \g__cfflatex_contact_index_int
      {
        \msg_expandable_error:nn { import-citation-cff } { not-in-contact-loop }
      }
  }

% Title page authors ---------------------------------------------------------
%
% \cffsetauthors[<keys>] declares the authors of the citation for \maketitle.
% Each author gets marks: the marks of their affiliations, numbered among the
% distinct affiliations of the citation, a footnote for each contact of the
% citation with the same names, and a footnote for each of their notes, given
% by the note key. The other keys give templates for the name, the footnote of
% a contact, and the commands that declare an author and an affiliation.

% Templates set by the keys; #1 of \__cfflatex_name:n and \__cfflatex_contact:n
% is a field getter, such as \cffauthor{2}, which takes a field.
\cs_new:Npn \__cfflatex_name:n #1 {}
\cs_new:Npn \__cfflatex_contact:n #1 {}
\cs_new:Npn \__cfflatex_affiliation_mark:n #1 {}
\cs_new_protected:Npn \__cfflatex_put_author:nn #1#2 {}
\cs_new_protected:Npn \__cfflatex_put_affiliation:nn #1#2 {}
% Styles perform their own preparation, then send declarations through this
% function. The exporter replaces only this output operation.
\cs_new_protected:Npn \__cfflatex_emit:n #1 {#1}
\NewDocumentCommand \cffemit {+m} {\__cfflatex_emit:n {#1}}
\tl_new:N \l__cfflatex_separator_tl
\bool_new:N \l__cfflatex_affiliations_bool
\bool_new:N \l__cfflatex_contacts_bool
\bool_new:N \l__cfflatex_style_valid_bool
\bool_new:N \g__cfflatex_export_bool
\prop_new:N \g__cfflatex_author_styles_prop
\tl_new:N \l__cfflatex_style_tl
\tl_new:N \l__cfflatex_style_keys_tl
\tl_new:N \l__cfflatex_style_file_tl
\tl_new:N \l__cfflatex_author_options_tl
\clist_new:N \l__cfflatex_style_requires_clist
\tl_new:N \l__cfflatex_style_validate_tl
\tl_new:N \l__cfflatex_style_begin_tl
\tl_new:N \l__cfflatex_style_end_tl
\tl_new:N \l__cfflatex_style_render_tl
\int_new:N \l__cfflatex_style_match_int
% Whether the keys being set come from a style definition, and the style that
% the last \cffsetauthors used.
\bool_new:N \l__cfflatex_style_keys_bool
\tl_new:N \g__cfflatex_last_style_tl
\regex_const:Nn \c__cfflatex_style_regex { \A [A-Za-z0-9] [-A-Za-z0-9_]* \Z }
\cs_new_protected:Npn \__cfflatex_prepare_author:n #1 {}

% Literal names are also used in filenames: do not accept paths or macros.
\prg_new_protected_conditional:Npnn \__cfflatex_if_style_name:n #1 { TF }
  {
    \regex_count:NnN \c__cfflatex_style_regex {#1} \l__cfflatex_style_match_int
    \int_compare:nNnTF { \l__cfflatex_style_match_int } = { 1 }
      { \prg_return_true: }
      { \prg_return_false: }
  }
\NewDocumentCommand \cffdeclareauthorstyle {m +m}
  {
    \__cfflatex_if_style_name:nTF {#1}
      {
        \prop_if_in:NnTF \g__cfflatex_author_styles_prop {#1}
          { \msg_error:nnn { import-citation-cff } { style-duplicate } {#1} }
          { \prop_gput:Nnn \g__cfflatex_author_styles_prop {#1} {#2} }
      }
      { \msg_error:nnn { import-citation-cff } { style-name } {#1} }
  }
% Read definition files with normal document catcodes, restoring the caller's
% expl3 syntax afterwards. Plugins may turn expl3 syntax on for their helpers.
\cs_new_protected:Npn \__cfflatex_input_style:n #1
  {
    \exp_args:Ne \__cfflatex_input_style:nn { \char_value_catcode:n { 58 } }
      {#1}
  }
\cs_new_protected:Npn \__cfflatex_input_style:nn #1#2
  {
    \ExplSyntaxOff
    \file_input:n {#2}
    \int_compare:nNnTF {#1} = { 11 }
      { \ExplSyntaxOn } { \ExplSyntaxOff }
  }
\cs_new_protected:Npn \__cfflatex_load_style:n #1
  {
    \__cfflatex_if_style_name:nTF {#1}
      {
        \prop_if_in:NnF \g__cfflatex_author_styles_prop {#1}
          {
            \file_get_full_name:nNF
              { \c__cfflatex_package_path_tl cfflatex-style-#1.def }
            \l__cfflatex_style_file_tl
              {
                \file_get_full_name:nNF { cfflatex-style-#1.def }
                \l__cfflatex_style_file_tl
                  { \tl_clear:N \l__cfflatex_style_file_tl }
              }
            \tl_if_empty:NTF \l__cfflatex_style_file_tl
              { \msg_error:nnn { import-citation-cff } { style-missing } {#1} }
              {
                \exp_args:NV \__cfflatex_input_style:n
                \l__cfflatex_style_file_tl
                \prop_if_in:NnF \g__cfflatex_author_styles_prop {#1}
                  {
                    \msg_error:nnn { import-citation-cff }
                      { style-not-registered } {#1}
                  }
              }
          }
      }
      { \msg_error:nnn { import-citation-cff } { style-name } {#1} }
  }
\keys_define:nn { import-citation-cff / author-style }
  {
    style .tl_set:N = \l__cfflatex_style_tl,
    style .value_required:n = true,
  }
\cs_new_protected:Npn \__cfflatex_style_only:n #1
  {
    \bool_if:NF \l__cfflatex_style_keys_bool
      { \msg_error:nnn { import-citation-cff } { style-only-key } {#1} }
  }
\keys_define:nn { import-citation-cff / authors }
  {
    % The check reads these keys from the style definition by itself.
    check-fields .code:n = { \__cfflatex_style_only:n { check-fields } },
    check-region .code:n = { \__cfflatex_style_only:n { check-region } },
    requires .clist_set:N = \l__cfflatex_style_requires_clist,
    validate .tl_set:N = \l__cfflatex_style_validate_tl,
    begin .tl_set:N = \l__cfflatex_style_begin_tl,
    end .tl_set:N = \l__cfflatex_style_end_tl,
    render .tl_set:N = \l__cfflatex_style_render_tl,
    prepare-author .code:n =
      { \cs_set_protected:Npn \__cfflatex_prepare_author:n ##1 {#1} },
    name .code:n = { \cs_set:Npn \__cfflatex_name:n ##1 {#1} },
    note .code:n = { \__cfflatex_add_note:nn #1 },
    contact .code:n =
      {
        \tl_if_blank:nTF {#1}
          { \bool_set_false:N \l__cfflatex_contacts_bool }
          {
            \bool_set_true:N \l__cfflatex_contacts_bool
            \cs_set:Npn \__cfflatex_contact:n ##1 {#1}
          }
      },
    separator .tl_set:N = \l__cfflatex_separator_tl,
    affiliation-mark .choice:,
    affiliation-mark / alph .code:n =
      { \cs_set_eq:NN \__cfflatex_affiliation_mark:n \int_to_alph:n },
    affiliation-mark / Alph .code:n =
      { \cs_set_eq:NN \__cfflatex_affiliation_mark:n \int_to_Alph:n },
    affiliation-mark / arabic .code:n =
      { \cs_set:Npn \__cfflatex_affiliation_mark:n ##1 { \int_eval:n {##1} } },
    affiliation-mark / roman .code:n =
      { \cs_set_eq:NN \__cfflatex_affiliation_mark:n \int_to_roman:n },
    affiliation-mark / Roman .code:n =
      { \cs_set_eq:NN \__cfflatex_affiliation_mark:n \int_to_Roman:n },
    author .code:n =
      {
        \cs_set_protected:Npn \__cfflatex_put_author:nn ##1##2
          { \cffemit {#1} }
      },
    author-code .code:n =
      { \cs_set_protected:Npn \__cfflatex_put_author:nn ##1##2 {#1} },
    affiliation .code:n =
      {
        \keys_set:nn { import-citation-cff / authors }
          { affiliation-code = { \cffemit {#1} } }
        \tl_if_blank:nT {#1}
          { \bool_set_false:N \l__cfflatex_affiliations_bool }
      },
    affiliation-code .code:n =
      {
        \bool_set:Nn \l__cfflatex_affiliations_bool { ! \tl_if_blank_p:n {#1} }
        \cs_set_protected:Npn \__cfflatex_put_affiliation:nn ##1##2 {#1}
      },
  }
% Reset every setting before applying a style and the user's overrides.
\tl_const:Nn \c__cfflatex_author_defaults_tl
  {
    requires = {}, validate = {}, begin = {}, end = {}, render = {},
    prepare-author = {}, author = {}, affiliation = {},
    name = { #1 { given-names } \nobreakspace #1 { family-names } },
    contact = { E-mail:~#1 { email } },
    separator = { , },
    affiliation-mark = alph,
  }

% Like \thanks in \maketitle, but typesets the footnote symbol as text among
% the marks of an author, so that it does not overlap them.
\cs_new_protected:Npn \__cfflatex_thanks:n #1
  {
    \stepcounter {footnote}
    \protected@xdef \@thefnmark {\thefootnote}
    \@thefnmark
    \protected@xdef \@thanks
      {\@thanks \protect \footnotetext [\int_use:N \c@footnote] {#1}}
  }

% The names of the #2-th entry of the authors or the contacts #1, which
% identify a contact with an author.
\cs_new:Npn \__cfflatex_names:nn #1#2
  {
    \prop_item:Nn \g__cfflatex_values_prop { #1 / #2 / given-names } |
    \prop_item:Nn \g__cfflatex_values_prop { #1 / #2 / family-names } |
    \prop_item:Nn \g__cfflatex_values_prop { #1 / #2 / name }
  }

\tl_new:N \g__cfflatex_author_names_tl
\cs_generate_variant:Nn \seq_use:Nn { NV }
\seq_new:N \l__cfflatex_marks_seq
\seq_new:N \l__cfflatex_names_seq
% The notes of the note key, as {<author>}{<text>} items.
\seq_new:N \l__cfflatex_notes_seq
\cs_new_protected:Npn \__cfflatex_add_note:nn #1#2
  {
    \bool_lazy_or:nnTF { \int_compare_p:nNn {#1} < { 1 } }
      { \int_compare_p:nNn {#1} > { \g__cfflatex_author_count_int } }
      {
        \msg_error:nne { import-citation-cff }
          { author-index } { \int_eval:n {#1} }
      }
      {
        \seq_put_right:Ne \l__cfflatex_notes_seq
          { { \int_eval:n {#1} } { \exp_not:n {#2} } }
      }
  }
% Adds a footnote with the text #3 to the marks of the #1-th author if the note
% is for the #2-th author.
\cs_new_protected:Npn \__cfflatex_add_note_mark:nnn #1#2#3
  {
    \int_compare:nNnT {#1} = {#2}
      { \seq_put_right:Nn \l__cfflatex_marks_seq { \__cfflatex_thanks:n {#3} } }
  }
\tl_new:N \l__cfflatex_marks_tl
\tl_new:N \l__cfflatex_name_tl
\tl_new:N \l__cfflatex_author_who_tl
\tl_new:N \l__cfflatex_contact_who_tl
\tl_new:N \l__cfflatex_contact_tl

\NewDocumentCommand \cffsetauthors {O{}}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      { \__cfflatex_setup_authors:n {#1} }
      { \msg_error:nn { import-citation-cff } { not-loaded } }
  }
\cs_new_protected:Npn \__cfflatex_setup_authors:n #1
  {
    \seq_clear:N \l__cfflatex_notes_seq
    \keys_set:nV { import-citation-cff / authors }
    \c__cfflatex_author_defaults_tl
    % The style of the document is the default, or else standard.
    \tl_if_empty:NTF \g__cfflatex_document_style_tl
      { \tl_set:Nn \l__cfflatex_style_tl { standard } }
      { \tl_set_eq:NN \l__cfflatex_style_tl \g__cfflatex_document_style_tl }
    % Select the style first, regardless of where style= occurs in the list.
    \keys_set_known:nnN { import-citation-cff / author-style } {#1}
    \l__cfflatex_author_options_tl
    \exp_args:NV \__cfflatex_load_style:n \l__cfflatex_style_tl
    \prop_get:NVNT \g__cfflatex_author_styles_prop \l__cfflatex_style_tl
    \l__cfflatex_style_keys_tl
      {
        \tl_gset_eq:NN \g__cfflatex_last_style_tl \l__cfflatex_style_tl
        \bool_set_true:N \l__cfflatex_style_keys_bool
        \keys_set:nV { import-citation-cff / authors }
        \l__cfflatex_style_keys_tl
        \bool_set_false:N \l__cfflatex_style_keys_bool
        \keys_set:nV { import-citation-cff / authors }
        \l__cfflatex_author_options_tl
        \bool_set_true:N \l__cfflatex_style_valid_bool
        \bool_if:NF \g__cfflatex_export_bool
          {
            \clist_map_inline:Nn \l__cfflatex_style_requires_clist
              {
                \IfPackageLoadedTF {##1} {}
                  {
                    \bool_set_false:N \l__cfflatex_style_valid_bool
                    \msg_error:nnee { import-citation-cff }
                      { style-package-missing }
                      { \l__cfflatex_style_tl } {##1}
                  }
              }
            \bool_if:NT \l__cfflatex_style_valid_bool
              { \tl_use:N \l__cfflatex_style_validate_tl }
          }
        \bool_if:NT \l__cfflatex_style_valid_bool { \__cfflatex_set_authors: }
      }
  }
\cs_new_protected:Npn \__cfflatex_set_authors:
  {
    % Name collection is independent of the renderer and declaration order.
    \seq_clear:N \l__cfflatex_names_seq
    \int_step_inline:nn { \g__cfflatex_author_count_int }
      {
        \tl_set:No \l__cfflatex_name_tl
          { \__cfflatex_name:n { \cffauthor {##1} } }
        \seq_put_right:NV \l__cfflatex_names_seq \l__cfflatex_name_tl
      }
    \__cfflatex_store_author_names:
    \tl_use:N \l__cfflatex_style_begin_tl
    \tl_if_empty:NTF \l__cfflatex_style_render_tl
      {
        \cffforeachauthor {\cffrenderauthor {\cffauthorindex}}
        \bool_if:NT \l__cfflatex_affiliations_bool
          {
            \cffforeachaffiliation
              {\cffrenderaffiliation {\cffaffiliationindex}}
          }
      }
      { \tl_use:N \l__cfflatex_style_render_tl }
    \tl_use:N \l__cfflatex_style_end_tl
  }
% A custom renderer can reuse the configured templates in another order.
\NewDocumentCommand \cffrenderauthor {m}
  {
    \__cfflatex_if_author:nT {#1}
      { \exp_args:Ne \__cfflatex_set_author:n { \int_eval:n {#1} } }
  }
\NewDocumentCommand \cffrenderaffiliation {m}
  {
    \bool_if:NTF \g__cfflatex_loaded_bool
      {
        \__cfflatex_if_affiliation:nnT {#1}
          { \__cfflatex_count:n { affiliation-count } }
          {
            \bool_if:NT \l__cfflatex_affiliations_bool
              {
                \exp_args:Nee \__cfflatex_put_affiliation:nn
                  { \__cfflatex_affiliation_mark:n {#1} }
                  { \exp_not:N \cffaffiliation {\int_eval:n {#1}} }
              }
          }
      }
      { \msg_error:nn { import-citation-cff } { not-loaded } }
  }
% Kept separate so export can preserve class-defined formatting commands
% while resolving CFF fields, rather than expanding arbitrary class code.
\cs_new_protected:Npn \__cfflatex_store_author_names:
  {
    \tl_gset:Ne \g__cfflatex_author_names_tl
      { \seq_use:Nn \l__cfflatex_names_seq { ,~ } }
  }
% Declares the #1-th author.
\cs_new_protected:Npn \__cfflatex_set_author:n #1
  {
    \seq_clear:N \l__cfflatex_marks_seq
    \bool_if:NT \l__cfflatex_affiliations_bool
      {
        \int_step_inline:nn
          { \__cfflatex_count:n { authors / #1 / affiliation-count } }
          {
            \seq_put_right:Ne \l__cfflatex_marks_seq
              {
                \__cfflatex_affiliation_mark:n
                  {
                    \prop_item:Nn \g__cfflatex_values_prop
                      { authors / #1 / affiliation-indices / ##1 }
                  }
              }
          }
      }
    \bool_if:NT \l__cfflatex_contacts_bool
      {
        \tl_set:Ne \l__cfflatex_author_who_tl
          { \__cfflatex_names:nn { authors } {#1} }
        \int_step_inline:nn { \__cfflatex_count:n { contact-count } }
          {
            \tl_set:Ne \l__cfflatex_contact_who_tl
              { \__cfflatex_names:nn { contact } {##1} }
            \tl_if_eq:NNT \l__cfflatex_author_who_tl \l__cfflatex_contact_who_tl
              {
                \tl_set:No \l__cfflatex_contact_tl
                  { \__cfflatex_contact:n { \cffcontact {##1} } }
                \seq_put_right:Ne \l__cfflatex_marks_seq
                  {
                    \exp_not:N \__cfflatex_thanks:n
                      { \exp_not:V \l__cfflatex_contact_tl }
                  }
              }
          }
      }
    \seq_map_inline:Nn \l__cfflatex_notes_seq
      { \__cfflatex_add_note_mark:nnn {#1} ##1 }
    \tl_set:Ne \l__cfflatex_marks_tl
      { \seq_use:NV \l__cfflatex_marks_seq \l__cfflatex_separator_tl }
    \__cfflatex_prepare_author:n {#1}
    % \protect keeps \cffauthor for \maketitle, where the check sees it, when
    % the template expands the name, as the \author of authblk does.
    \tl_set:No \l__cfflatex_name_tl
      { \__cfflatex_name:n { \protect \cffauthor {#1} } }
    \exp_args:NVV \__cfflatex_put_author:nn
    \l__cfflatex_marks_tl \l__cfflatex_name_tl
  }

% \cffauthornames expands to the names of the authors, separated by commas, as
% the name template of \cffsetauthors makes them.
\NewExpandableDocumentCommand \cffauthornames {}
  {\tl_use:N \g__cfflatex_author_names_tl}

% Built-ins use the same registration API as external definition files.
\__cfflatex_load_style:n { standard }
\__cfflatex_load_style:n { authblk }

% The check of the document --------------------------------------------------
%
% At \begin{document}, the check takes its fields and regions from the style
% option of the package, or else from the style of the last \cffsetauthors in
% the preamble, or else from standard. A style definition can give
% check-fields, a list of fields of the citation, where authors stands for
% every author, and check-region, a list of regions: maketitle, hooks =
% {<begin hook>}{<end hook>}, and document as the fallback.
\int_new:N \l__cfflatex_check_id_int
\tl_new:N \l__cfflatex_region_tl
\cs_generate_variant:Nn \hook_gput_code:nnn { nne }
\keys_define:nn { import-citation-cff / check }
  {
    check-fields .clist_gset:N = \g__cfflatex_check_fields_clist,
    check-region .code:n =
      {
        \seq_gclear:N \g__cfflatex_check_regions_seq
        \bool_gset_false:N \g__cfflatex_check_document_bool
        \keys_set:nn { import-citation-cff / check-region } {#1}
      },
  }
\keys_define:nn { import-citation-cff / check-region }
  {
    maketitle .code:n =
      { \seq_gput_right:Nn \g__cfflatex_check_regions_seq { maketitle } },
    maketitle .value_forbidden:n = true,
    document .code:n = { \bool_gset_true:N \g__cfflatex_check_document_bool },
    document .value_forbidden:n = true,
    hooks .code:n =
      {
        \int_compare:nNnTF { \tl_count:n {#1} } = { 2 }
          { \__cfflatex_check_hooks:nn #1 }
          {
            \msg_error:nnn { import-citation-cff }
              { check-region } { hooks~=~#1 }
          }
      },
    hooks .value_required:n = true,
    unknown .code:n =
      {
        \msg_error:nne { import-citation-cff }
          { check-region } { \l_keys_key_str }
      },
  }
% The region hooks<n> opens at the hook #1 and closes at the hook #2.
\cs_new_protected:Npn \__cfflatex_check_hooks:nn #1#2
  {
    \tl_set:Ne \l__cfflatex_region_tl
      { hooks \int_eval:n { \seq_count:N \g__cfflatex_check_regions_seq + 1 } }
    \seq_gput_right:NV \g__cfflatex_check_regions_seq \l__cfflatex_region_tl
    \hook_gput_code:nne {#1} { import-citation-cff }
      { \__cfflatex_region_begin:n { \l__cfflatex_region_tl } }
    \hook_gput_code:nne {#2} { import-citation-cff }
      { \__cfflatex_region_end:n { \l__cfflatex_region_tl } }
  }
\cs_new_protected:Npn \__cfflatex_check_setup:
  {
    \tl_if_empty:NF \g__cfflatex_document_style_tl
      { \exp_args:NV \__cfflatex_load_style:n \g__cfflatex_document_style_tl }
    \bool_if:NT \g__cfflatex_check_bool
      {
        \tl_gset:Ne \g__cfflatex_check_style_tl
          {
            \tl_if_empty:NTF \g__cfflatex_document_style_tl
              {
                \tl_if_empty:NTF \g__cfflatex_last_style_tl
                  { standard } { \exp_not:V \g__cfflatex_last_style_tl }
              }
              { \exp_not:V \g__cfflatex_document_style_tl }
          }
        \clist_gset:Nn \g__cfflatex_check_fields_clist { title, authors }
        \seq_gset_from_clist:Nn \g__cfflatex_check_regions_seq { maketitle }
        \bool_gset_false:N \g__cfflatex_check_document_bool
        \prop_get:NVNT \g__cfflatex_author_styles_prop
        \g__cfflatex_check_style_tl \l__cfflatex_style_keys_tl
          {
            \exp_args:NnV \keys_set_known:nn { import-citation-cff / check }
            \l__cfflatex_style_keys_tl
          }
        % Fields other than the authors are numbered -1, -2, and so on.
        \prop_gclear:N \g__cfflatex_check_ids_prop
        \int_zero:N \l__cfflatex_check_id_int
        \clist_map_inline:Nn \g__cfflatex_check_fields_clist
          {
            \str_if_eq:nnF {##1} { authors }
              {
                \int_decr:N \l__cfflatex_check_id_int
                \prop_gput:Nne \g__cfflatex_check_ids_prop {##1}
                  { \int_use:N \l__cfflatex_check_id_int }
              }
          }
        \bool_if:NT \g__cfflatex_check_document_bool
          { \__cfflatex_region_begin:n { document } }
      }
  }
\AddToHook {begindocument} [import-citation-cff] {\__cfflatex_check_setup:}
\tl_if_empty:NF \g__cfflatex_document_style_tl
  {
    \exp_args:NV \__cfflatex_if_style_name:nTF \g__cfflatex_document_style_tl
      {}
      {
        \msg_error:nne { import-citation-cff } { style-name }
          { \tl_use:N \g__cfflatex_document_style_tl }
        \tl_gclear:N \g__cfflatex_document_style_tl
      }
  }

\endinput