%D \module
%D   [       file=font-sty,
%D        version=2011.01.13, % (copied fron font-ini)
%D          title=\CONTEXT\ Font Macros,
%D       subtitle=Styles,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

\writestatus{loading}{ConTeXt Font Macros / Styles}

\unprotect

%D \macros
%D   {definealternativestyle}
%D
%D In the main modules we are going to implement lots of
%D parameterized commands and one of these parameters will
%D concern the font to use. To suit consistent use of fonts we
%D here implement a mechanism for defining the keywords that
%D present a particular style or alternative.
%D
%D \starttyping
%D \definealternativestyle [keywords] [\style] [\nostyle]
%D \stoptyping
%D
%D The first command is used in the normal textflow, while the
%D second command takes care of headings and alike. Consider
%D the next two definitions:
%D
%D \starttyping
%D \definealternativestyle [bold] [\bf]  []
%D \definealternativestyle [cap]  [\cap] [\cap]
%D \stoptyping
%D
%D A change \type{\bf} in a heading which is to be set in
%D \type{\tfd} does not look that well, so therefore we leave
%D the second argument of \type{\definealternativestyle} empty.
%D When we capatalize characters using the pseudo small cap
%D command \type{\cap}, we want this to take effect in both
%D text and headings, which is accomplished by assigning both
%D arguments.

\installcorenamespace{alternativestyles}

\setnewconstant \c_font_current_alternative_style_index \plusone

\unexpanded\def\definealternativestyle
  {\dotripleempty\font_basics_define_alternative_style}

\def\font_basics_define_alternative_style[#commands][#variantone][#varianttwo]%
  {\processcommalist[#commands]{\font_basics_define_alternative_style_indeed{#variantone}{#varianttwo}}}

\let\definestyle\definealternativestyle % later redefined

\def\font_basics_define_alternative_style_indeed#variantone#varianttwo#command%
  {\ifcsname#command\endcsname
     % no redefinition
   \else
     \setuvalue{#command}{\groupedcommand{#variantone}{}}%
   \fi
   \setvalue{\??alternativestyles#command}{\font_helpers_apply_alternative_style{#variantone}{#varianttwo}}}%

\def\font_helpers_apply_alternative_style
  {\ifcase\c_font_current_alternative_style_index
     \expandafter\gobbletwoarguments
   \or
     \expandafter\firstoftwoarguments
   \or
     \expandafter\secondoftwoarguments
   \else
     \expandafter\firstoftwoarguments
   \fi}

\def\applyalternativestyle#name% public
  {\begincsname\??alternativestyles#name\endcsname}

%D Maybe too geneneric, but probably ok is the following. (Maybe one
%D day we will use a dedicated grouped command for styles.)

% \appendtoks
%     \let\groupedcommand\thirdofthreearguments
% \to \everysimplifycommands

%D This command also defines the keyword as command. This means
%D that the example definition of \type{bold} we gave before,
%D results in a command \type{\bold} which can be used as:
%D
%D \startbuffer
%D He's a \bold{bold} man with a {\bold head}.
%D \stopbuffer
%D
%D \typebuffer
%D
%D or
%D
%D \startexample
%D \definealternativestyle[bold][\bf][]\getbuffer
%D \stopexample
%D
%D Such definitions are of course unwanted for \type{\cap}
%D because this would result in an endless recursive call.
%D Therefore we check on the existance of both the command and
%D the substitution. The latter is needed because for instance
%D \type{\type} is an entirely diferent command. That command
%D handles verbatim, while the style command would just switch
%D to teletype font. This is just an example of a tricky
%D naming coincidence.

%D \macros
%D   {doconvertfont,noconvertfont,
%D    dontconvertfont,redoconvertfont}
%D
%D After having defined such keywords, we can call for them by
%D using
%D
%D \starttyping
%D \doconvertfont{keyword}{text}
%D \stoptyping
%D
%D We deliberately pass an argument. This enables us to
%D assign converters that handle one argument, like
%D \type{\cap}.
%D
%D By default the first specification is used to set the style,
%D exept when we say \type{\dontconvertfont}, after which the
%D second specification is used. We can also directly call for
%D \type{\noconvertfont}. In nested calls, we can restore the
%D conversion by saying \type{\redoconvertfont}.

%D These commands are not grouped! Grouping is most probably
%D done by the calling macro's and would lead to unnecessary
%D overhead.

\let\m_current_convert_font   \empty
\let\m_current_convert_font_dt\empty

\unexpanded\def\doconvertfont#specification% takes second argument / this command is obsolete
  {\edef\m_current_convert_font{#specification}%
   \ifx\m_current_convert_font\empty
    %\expandafter\firstofoneargument
   \else
     \expandafter\font_helpers_do_convert_font
   \fi}

\def\font_helpers_do_convert_font
  {\edef\m_current_convert_font_dt{\detokenize\expandafter{\m_current_convert_font}}%
   \ifcsname\??alternativestyles\m_current_convert_font_dt\endcsname
     \expandafter\lastnamedcs
   \else\ifcsname\m_current_convert_font_dt\endcsname
     \doubleexpandafter\lastnamedcs
   \else
     \doubleexpandafter\m_current_convert_font
   \fi\fi}

%D Low level switches (downward compatible, but we keep them as one can use
%D them in styles):
%D
%D \starttyping
%D \usemodule[abr-02]
%D \setuphead[chapter][style=\bfb]
%D \setupfooter[style=\dontconvertfont\bf]
%D \chapter{This is \TEX}
%D \stoptyping

\unexpanded\def\dontconvertfont{\c_font_current_alternative_style_index\plustwo} % needs checking in usage
\unexpanded\def\redoconvertfont{\c_font_current_alternative_style_index\plusone} % needs checking in usage

%D The new one:

\setfalse\fontattributeisset

\unexpanded\def\dousestyleparameter#value%
  {\edef\currentstyleparameter{#value}%
   \ifx\currentstyleparameter\empty\else
     \expandafter\dousecurrentstyleparameter
   \fi}

\unexpanded\def\dousestylehashparameter#hash#parameter%
  {\ifcsname#hash#parameter\endcsname
     \expandafter\dousestyleparameter\lastnamedcs
   \fi}

\unexpanded\def\dousecurrentstyleparameter % empty check outside here
  {\edef\detokenizedstyleparameter{\detokenize\expandafter{\currentstyleparameter}}%
   \settrue\fontattributeisset % reset is done elsewhere
   \ifcsname\??alternativestyles\detokenizedstyleparameter\endcsname
     \lastnamedcs
   \else\ifcsname\detokenizedstyleparameter\endcsname
     \lastnamedcs
   \else
     \currentstyleparameter
   \fi\fi}

\let\dosetfontattribute\dousestylehashparameter % for a while

%D New commands (not yet interfaced):
%D
%D \startbuffer
%D \definestyle[one][style=bold,color=darkblue]
%D
%D test \one{test} test
%D test \style[one]{test} test
%D test \style[color=red]{test} test
%D test \style[Serif at 20pt]{test} test
%D \stopbuffer
%D
%D \typebuffer \startlines \getbuffer \stoplines

% definitions .. no tagging here

\installcorenamespace{style}
\installcorenamespace{stylecheck}

\installcommandhandler \??style {style} \??style

\setupstyle
  [%\c!style=,
   %\c!color=,
   \c!method=\v!command]

\appendtoks
    \letvalue{\??stylecheck\currentstyle}\relax
    \edef\p_method{\styleparameter\c!method}%
    \ifx\p_method\v!command
        \setuevalue{\e!start\currentstyle}{\font_styles_apply_start{\currentstyle}}%
        \setuevalue{\e!stop \currentstyle}{\font_styles_apply_stop}%
        \setuevalue        {\currentstyle}{\font_styles_apply_grouped{\currentstyle}}% no longer groupedcommand here
    \fi
\to \everydefinestyle

\unexpanded\def\font_styles_apply_start#name%
  {\begingroup
   \font_styles_use_defined{#name}}

\unexpanded\def\font_styles_apply_stop
  {\endgroup}

\unexpanded\def\font_styles_apply_grouped#name% assumes that the next is { or \bgroup
  {\bgroup
   \def\g_style{\font_styles_use_defined{#name}}%
   \afterassignment\g_style
   \let\nexttoken}

\unexpanded\def\font_styles_use_defined#name%
  {\edef\currentstyle{#name}%
   \usestylestyleandcolor\c!style\c!color}

\unexpanded\def\font_styles_use_generic#specification%
  {\let\currentstyle\s!unknown % reasonable generic tag
   \letstyleparameter\c!style\empty
   \letstyleparameter\c!color\empty
   \setupcurrentstyle[#specification]%
   \usestylestyleandcolor\c!style\c!color}

% commands

\installcorenamespace{styleargument}

\unexpanded\def\style[#name]% as this is can be a switch we use groupedcommand
  {\csname\??styleargument
     \ifcsname\??stylecheck#name\endcsname
       2% defined as style
     \else\ifcsname#name\endcsname
       1% defined as command
     \else
       3% specification
     \fi\fi
   \endcsname{#name}}

\setvalue{\??styleargument1}#name%
  {\groupedcommand{\csname#name\endcsname}{}}

\setvalue{\??styleargument2}#name%
  {\groupedcommand{\font_styles_use_defined{#name}}{}} % or {\font_styles_apply_grouped{#name}}

\setvalue{\??styleargument3}#specification%
  {\doifelseassignment{#specification}\font_styles_assignment\font_styles_direct{#specification}}

\def\font_styles_assignment#specification{\groupedcommand{\font_styles_use_generic{#specification}}{}}
\def\font_styles_direct    #specification{\groupedcommand{\definedfont[#specification]}{}}

% environments

\installcorenamespace{styleenvironment}

\unexpanded\def\startstyle[#name]%
  {\begingroup
   \csname\??styleenvironment
     \ifcsname\??stylecheck#name\endcsname
       2% defined as style
     \else\ifcsname#name\endcsname
       1% defined as command
     \else
       3% specification
     \fi\fi
   \endcsname{#name}}

\unexpanded\def\stopstyle
  {\endgroup
   \autoinsertnextspace} % will be configurable, maybe also in \definestartstop

\setvalue{\??styleenvironment1}#name%
  {\csname#name\endcsname}

\setvalue{\??styleenvironment2}#name%
  {\font_styles_use_defined{#name}}

\setvalue{\??styleenvironment3}#specification%
  {\doifelseassignment{#specification}\font_styles_start_assignment\font_styles_start_direct{#specification}}

\def\font_styles_start_assignment#specification{\font_styles_use_generic{#specification}}
\def\font_styles_start_direct    #specification{\definedfont[#specification]\relax}

%D Still experimental (might even go away).

% \definestylecollection[mine]

% \definestyleinstance[mine][default][sorry]
% \definestyleinstance[mine][tt][bs][ttbs:\rm\sl]
% \definestyleinstance[mine][tt][bf][ttbf:\rm\sl]
% \definestyleinstance[mine][bf][\sl]
% \definestyleinstance[mine][sl][\tt]

% {\bf test \mine test \sl test \mine test \bs oeps \mine oeps {\tt test \mine \bf test}}

\installcorenamespace{stylecollection}

\unexpanded\def\definestylecollection
  {\dosingleargument\font_styles_define_style_collection}

\def\font_styles_define_style_collection[#name]%
  {\iffirstargument
     \setuvalue{#name}{\styleinstance[#name]}%
     \def\font_styles_define_style_collection_a#style%
       {\def\font_styles_define_style_collection_b#alternative{\undefinevalue{\??stylecollection#name:#style:#alternative}}%
        \font_helpers_process_alternative_list\font_styles_define_style_collection_b
        \font_styles_define_style_collection_b\s!default}%
     \font_helpers_process_style_list\font_styles_define_style_collection_a
     \font_styles_define_style_collection_a\s!default
  \fi}

\let\font_styles_define_style_collection_a\relax
\let\font_styles_define_style_collection_b\relax

\unexpanded\def\definestyleinstance
  {\doquadrupleargument\font_styles_define_style_instance}

\def\font_styles_define_style_instance[#instance][#2][#3][#4]% [name] [rm|ss|tt|..] [sl|bf|...] [whatever]
  {\iffirstargument
     \ifcsname#instance\endcsname\else\font_styles_define_style_collection[#instance]\fi
   \fi
   \iffourthargument
     \setvalue{\??stylecollection#instance:#2:#3}{#4}%
   \else\ifthirdargument
     \setvalue{\??stylecollection#instance::#2}{#3}%
   \else\ifsecondargument
     \letvalueempty{\??stylecollection#instance::#2}%
   \fi\fi\fi}

% \unexpanded\def\styleinstance[#instance]% will be made faster
%   {%\begingroup\normalexpanded{\noexpand\infofont[#1:\fontstyle:\fontalternative]}\endgroup
%    \executeifdefined{\??stylecollection#instance:\fontstyle:\fontalternative}%
%   {\executeifdefined{\??stylecollection#instance:\fontstyle:\s!default}%
%   {\executeifdefined{\??stylecollection#instance::\fontalternative}
%   {\getvalue        {\??stylecollection#instance::\s!default}}}}}

\unexpanded\def\styleinstance[#instance]% maybe \lastnamedcs here too
  {\csname\??stylecollection#instance:%
     \ifcsname\??stylecollection#instance:\fontstyle:\fontalternative\endcsname
       \fontstyle:\fontalternative
     \else\ifcsname\??stylecollection#instance:\fontstyle:\s!default\endcsname
       \fontstyle:\s!default
     \else\ifcsname\??stylecollection#instance::\fontalternative\endcsname
       :\fontalternative
     \else
       :\s!default
     \fi\fi\fi
   \endcsname}

%D Variant selectors
%D
%D \starttyping
%D \mathematics {\vsone{\utfchar{0x2229}}}
%D \mathematics {\utfchar{0x2229}\vsone{}}
%D \stoptyping

\unexpanded\edef\vsone#character{#character\normalUchar"FE00 } % used
\unexpanded\edef\vstwo#character{#character\normalUchar"FE01 } % not used but handy for testing

%D For historic reasons we keep the following around but they are no longer
%D that relevant for \MKIV.

\unexpanded\def\doattributes#1#2#3#4%
  {\begingroup  % geen \bgroup, anders in mathmode lege \hbox
   \dousestylehashparameter{#1}{#2}%
   \dousecolorhashparameter{#1}{#3}%
   #4%
   \endgroup}

\unexpanded\def\dostartattributes#1#2#3%
  {\begingroup  % geen \bgroup, anders in mathmode lege \hbox
   \dousestylehashparameter{#1}{#2}%
   \dousecolorhashparameter{#1}{#3}}

\let\dostopattributes\endgroup

%D New but it needs to be supported explicitly (as in natural tables).

\newconditional\c_font_styles_math

\unexpanded\def\font_styles_math_reset
  {\setfalse\c_font_styles_math}

\unexpanded\def\font_styles_math_start
  {\ifconditional\c_font_styles_math
     \startimath
   \fi
   \relax}

\unexpanded\def\font_styles_math_stop
  {\relax
   \ifconditional\c_font_styles_math
     \stopimath
   \fi}

\definealternativestyle[\v!math][\settrue\c_font_styles_math]

\protect \endinput
