%D \module
%D   [     file=t-syntax-highlight,
%D      version=2021.12.13,
%D        title=\CONTEXT\ User Module,
%D     subtitle=Code syntax highlighting,
%D       author=Aditya Mahajan,
%D         date=\currentdate,
%D    copyright=Aditya Mahajan,
%D        email=adityam <at> ieee <dot> org,
%D      license=Simplified BSD License]

\writestatus{loading}{Code syntax highlighting (ver: 2021.12.13)}

\startmodule    [syntax-highlight]
\usemodule      [syntax-groups]
\usemodule      [filter] % loads module-catcodes

\unprotectmodulecatcodes

\startinterface all
  \setinterfaceconstant {syntax}          {syntax}
  \setinterfaceconstant {highlight}       {highlight}
  \setinterfaceconstant {highlightcolor}  {highlightcolor}
\stopinterface

%D Name space

\definenamespace
    [syntaxhighlighting]
    [\c!type=module,
     \c!name=syntaxhighlighting,
     \c!command=\v!yes,
     setup=\v!list,
     \c!style=\v!no,
     \s!parent=syntaxhighlighting]

\appendtoks
    \defineexternalfilter[\currentsyntaxhighlighting]
                         [\s!parent=\????syntaxhighlighting\currentexternalfilter,
                          \c!taglabel=\vimtyping@id,
                          \c!tagdetail={\externalfilterparameter\c!alternative},
                        ]%
    \normalexpanded{\definelinenumbering [\currentsyntaxhighlighting]}%
    \setevalue{type\currentsyntaxhighlighting file}{\getvalue{process\currentsyntaxhighlighting file}}%
\to\everydefinesyntaxhighlighting

\define[1]\syntaxhighlighting@set_linenumbers
    {\def\syntaxhighlighting@linenumbering{\getvalue{current#1}}%
     \def\syntaxhighlighting@parameter{\getvalue{#1parameter}}%
     \normalexpanded{\setuplinenumbering[\syntaxhighlighting@linenumbering]
          [
                \c!method=\syntaxhighlighting@parameter{\c!number\c!method},
            \c!conversion=\syntaxhighlighting@parameter\c!numberconversion,
              \c!location=\syntaxhighlighting@parameter{\c!number\c!location},
                 \c!style=\syntaxhighlighting@parameter\c!numberstyle,
                 \c!color=\syntaxhighlighting@parameter\c!numbercolor,
                 \c!width=\syntaxhighlighting@parameter{\c!number\c!width},
                  \c!left=\syntaxhighlighting@parameter{\c!number\c!left},
                 \c!right=\syntaxhighlighting@parameter{\c!number\c!right},
               \c!command=\syntaxhighlighting@parameter\c!numbercommand,
              \c!distance=\syntaxhighlighting@parameter{\c!number\c!distance},
                 \c!align=\syntaxhighlighting@parameter{\c!number\c!align},
           ]}}

\appendtoks
  \syntaxhighlighting@set_linenumbers\syntaxhighlighting@id
\to\everysetupsyntaxhighlighting

\def\syntaxhighlighting@id {syntaxhighlighting}

%D Helper macro

\def\syntaxhighlighting@yes{\v!yes,\v!on}

\startsetups syntaxhighlighting@setup

  \edef\currentsyntaxhighlighting{\currentexternalfilter}
  \edef\colorscheme@name{\externalfilterparameter\c!alternative}

  \let\SYN\syntaxgroup
  \edef\HGL{\externalfilterparameter{\c!highlight\c!command}}
  \let\\\textbackslash
  \let\{\textbraceleft
  \let\}\textbraceright
  \let\SYNBOL\donothing
  \let\SYNEOL\donothing

  \setupbar[syntaxhighlightline][color=\externalfilterparameter\c!highlightcolor]

  \def\tab##1%
      {\dorecurse{##1}{\obeyedspace}}%

  \forgetall
  \the\everyinitializeverbatim
  \usealignparameter\externalfilterparameter
  \doifinset{\v!packed}{\externalfilterparameter\c!option}
      {\setupwhitespace[\v!none,\v!flexible]}%

  \doadaptleftskip{\externalfilterparameter\c!margin}%

  \doifinsetelse{\v!hyphenated}{\externalfilterparameter\c!option}
      {\setbreakpoints[compound]}
      {\language\minusone
       \resetbreakpoints}%

  \def\obeyedline{\strut\par}%
  \activatespacehandler{\????syntaxhighlighting\externalfilterparameter\c!space:\externalfilterparameter\c!lines}
  \setcatcodetable\externalfilter@minimal_catcodes%
  \letcharcode\endoflineasciicode\obeyedline
  \letcharcode\spaceasciicode\obeyedspace
  \raggedright
\stopsetups

\starttexdefinition syntaxhighlighting@read_command #1
    \syntaxhighlighting@linenumbering_start
    \ReadFile{#1}
    \syntaxhighlighting@linenumbering_stop
\stoptexdefinition

\starttexdefinition syntaxhighlighting@linenumbering_start
   \doifinsetelse{\externalfilterparameter\c!numbering}\syntaxhighlighting@yes
       {\let\SYNBOL=\syntaxhighlighting_begin_number_lines
        \let\SYNEOL=\syntaxhighlighting_end_number_lines
        \startlinenumbering
          [\currentsyntaxhighlighting]
          [
              \c!method=\v!type,
               \c!start=\externalfilterparameter{\c!number\c!start},
                \c!step=\externalfilterparameter{\c!number\c!step},
            \c!continue=\externalfilterparameter{\c!number\c!continue},
          ]}
        {\let\SYNBOL=\syntaxhighlighting_begin_lines
         \let\SYNEOL=\syntaxhighlighting_end_lines}
\stoptexdefinition

\starttexdefinition syntaxhighlighting@linenumbering_stop
   \doifinset{\externalfilterparameter\c!numbering}\syntaxhighlighting@yes
      {\stoplinenumbering}
\stoptexdefinition

\newcount\nofsyntaxhighlightinglines

\starttexdefinition syntaxhighlighting_begin_lines
  \dostarttaggednodetail\t!verbatimline
\stoptexdefinition

\starttexdefinition syntaxhighlighting_end_lines
  \dostoptagged
\stoptexdefinition

\starttexdefinition syntaxhighlighting_begin_number_lines
  \global\advance\nofsyntaxhighlightinglines\plusone
  \dostarttaggednodetail\t!verbatimline
  \attribute\verbatimlineattribute\nofsyntaxhighlightinglines
\stoptexdefinition

\starttexdefinition syntaxhighlighting_end_number_lines
  \attribute\verbatimlineattribute\attributeunsetvalue
  \dostoptagged
\stoptexdefinition


\setupsyntaxhighlighting
  [\c!tab=4,
   \c!space=\v!off,
   \c!lines=\v!fixed,
   \c!margin=\zeropoint,
   \c!start=1,
   \c!stop=0,
   % \c!syntax=context,
   \c!alternative=pscolor,
   \c!before=,
   \c!after=,
   \c!spacebefore=\v!none,
   \c!spaceafter=\v!none,
   \c!location=\v!paragraph,
   \c!style=\tttf,
   \c!color=,
   \c!align={\v!flushleft,\v!nothyphenated}, 
   \c!filtercommand=echo, % placeholder
   \c!continue=yes,
   \c!read=\v!yes,
   \c!readcommand=\syntaxhighlighting@read_command,
   \c!output=\externalfilterinputfile, % placeholder
   \c!setups=syntaxhighlighting@setup,
   \c!option=\v!packed, % \v!hyphenated
   \s!parent=\????externalfilter,
   % Numbering options
   \c!numbering=\v!no,
   \c!number\c!start=1,
   \c!number\c!step=1,
   \c!number\c!continue=\v!no,
   \c!numberconversion=\v!numbers,
   \c!number\c!method=\v!type, 
   \c!number\c!location=\v!left,
   \c!numberstyle=\ttx,
   \c!numbercolor=,
   \c!number\c!width=2em,
   \c!number\c!left=,
   \c!number\c!right=,
   \c!numbercommand=,
   \c!number\c!distance=0.5em,
   \c!number\c!align=\v!flushright,
   %Highlight options
   \c!highlight=,
   \c!highlightcolor=lightgray,
   \c!highlight\c!command=\syntaxhighlightline,
  ]

% Space handler

% Invisible space, don't split
\installspacemethod {\????syntaxhighlighting\v!off:\v!fixed}
  {\def\obeyedspace{\mathortext\normalspace\explicitfixedspace}}

% Invisible space, allow split
\installspacemethod {\????syntaxhighlighting\v!off:\v!split}
  {\def\obeyedspace{\mathortext\normalspace\explicitobeyedspace}}

% Visible space, don't split
\installspacemethod {\????syntaxhighlighting\v!on:\v!fixed}
  {\def\obeyedspace{\mathortext\normalspace\optionalcontrolspace}}

% Visible space, allow split
\installspacemethod {\????syntaxhighlighting\v!on:\v!split}
  {\def\obeyedspace{\mathortext\normalspace\explicitcontrolspace}}

% Default: line=empty
\installspacemethod {\????syntaxhighlighting\v!off:}
  {\activatespacehandler {\????syntaxhighlighting\v!off:\v!fixed}}

\installspacemethod {\????syntaxhighlighting\v!on}
  {\activatespacehandler {\????syntaxhighlighting\v!on:\v!fixed}}

% space=empty, line=something
\installspacemethod {\????syntaxhighlighting:\v!fixed}
  {\activatespacehandler {\????syntaxhighlighting\v!off:\v!fixed}}

\installspacemethod {\????syntaxhighlighting:\v!split}
  {\activatespacehandler {\????syntaxhighlighting\v!off:\v!split}}

% Both empty
\installspacemethod {\????syntaxhighlighting:}
  {\activatespacehandler {\????syntaxhighlighting\v!off:\v!fixed}}

\definebar[syntaxhighlightline]
          [\c!order=\v!background,
   \c!rulethickness=2.5,
           \c!method=0,
          \c!offset=1.375,
        \c!continue=\v!yes,
           \c!color=\externalfilterparameter\c!highlightcolor,
          ]

% For backward compatibility
\def\syntaxhighlighting@namespace {\????syntaxhighlighting}
\def\syntaxhighlighting@name      {\currentsyntaxhighlighting}

\protectmodulecatcodes

\stopmodule