%D \module
%D   [       file=typo-fln,
%D        version=2013.08.22, % comes from the few years older m-newstuff
%D          title=\CONTEXT\ Typesetting Macros,
%D       subtitle=First Lines,
%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 Typesetting Macros / First Lines}

%D I had this code laying around for a while \unknown\ probably as a side effect
%D of cleaning up the supp-fun modules. There is probably room for improvement
%D and more features.

% \setupbodyfont[pagella]
%
% \starttext
%
%     \setupindenting[medium,yes]
%
%     \definefirstline
%       [smallcaps]
%       [alternative=line,
%        color=darkred,
%        style=\setfontfeature{smallcaps}]
%
%     \setfirstline[smallcaps] \input tufte  \par
%     \setfirstline[smallcaps] \input ward   \par
%     \setfirstline[smallcaps] \input knuth  \par
%     \setfirstline[smallcaps] \input bryson \par
%
%     \definefirstline
%       [smallcaps]
%       [alternative=word,
%        color=darkblue,
%        style=bold,
%        n=2]
%
%     \setfirstline[smallcaps] \input tufte  \par
%     \setfirstline[smallcaps] \input ward   \par
%     \setfirstline[smallcaps] \input knuth  \par
%     \setfirstline[smallcaps] \input bryson \par
%
% \stoptext

\unprotect

\registerctxluafile{typo-fln}{1.001}

\definesystemattribute[firstline][public]

\installcorenamespace {firstline}

\installcommandhandler \??firstline {firstline} \??firstline

\setupfirstline
 [\c!alternative=\v!line,
  %\c!style=,
  %\c!color=,
   \c!n=0]

\appendtoks
   \begingroup
       \usefirstlinestyleandcolor\c!style\c!color
       \setxvalue{\??firstline:\currentfirstline}{\ctxlua{commands.definefirstline {
            alternative = "\firstlineparameter\c!alternative",
            ma          = \the\attribute\colormodelattribute,
            ca          = \the\attribute\colorattribute,
            ta          = \the\attribute\transparencyattribute,
            n           = \number\firstlineparameter\c!n,
            font        = \fontid\font,
            dynamic     = \number\attribute\zerocount,
       }}}%
   \endgroup
\to \everydefinefirstline

\unexpanded\def\setfirstline[#1]%
  {\ifcsname\??firstline:#1\endcsname
     \edef\typo_firstline_set{\typo_firstline_set_indeed{\number\csname\??firstline:#1\endcsname}}%
   \else
     \let\typo_firstline_set\relax
   \fi}

\unexpanded\def\typo_firstline_set_indeed#1%
  {\dontleavehmode
   \begingroup
   \attribute\firstlineattribute#1\relax
   \kern\zeropoint % we need a node
   \hskip\zeropoint\s!plus\emwidth\relax % can be an option
   \globallet\typo_firstline_set\relax
   \endgroup}

\let\typo_firstline_set\relax

% \appendtoks
%     \typo_firstline_set % has to be done later
% \to \everypar

\protect

\endinput