%D \module
%D   [       file=page-col,   % moved from page-ini
%D        version=2011.12.07, % 2000.10.20,
%D          title=\CONTEXT\ Page Macros,
%D       subtitle=Column Helpers,
%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 Page Macros / Column Helpers}

%D Here we implement a couple of helpers for dealing with columns. For
%D the moment we keep the names. When the mul and set modules are redone
%D these can be adapted or disappear.

%D DO WE STILL NEED THESE?

\unprotect

%D We reserve a counter for the number of columns as well as the current
%D column. Both are not to be changed by users!

%newinteger    \nofcolumns \nofcolumns\plusone % already in core-ini.mkiv
\newinteger    \mofcolumns \mofcolumns\plusone
\newdimension  \columnwidth
\newdimension  \columndistance
\newconstant   \columndirection % 0:lr 1:rl

\pushoverloadmode
    \newuserunit \columnwidth    cw % column width
    \newuserunit \columndistance cd % column distance
\popoverloadmode

\setnewconstant\maxnofcolumns       50
\setnewconstant\allocatednofcolumns  0

%D During initialization the temporary boxes are allocated. This enables us to
%D use as much columns as we want, without exhausting the pool of boxes too
%D fast. We could have packed them in one box, but we've got enough boxes.
%D
%D Two sets of boxes are declared, the txtboxes are used for the text, the
%D topboxes are for moved column floats.

\installcorenamespace{columntext}
\installcorenamespace{columnfooter}
\installcorenamespace{columntop}
\installcorenamespace{columnbottom}

\permanent\protected\def\initializecolumns#1%
  {\ifnum#1>\maxnofcolumns
     \showmessage\m!columns1\maxnofcolumns
     \nofcolumns\maxnofcolumns
   \else
     \nofcolumns#1\relax
   \fi
   \ifnum\nofcolumns>\allocatednofcolumns
     \page_columns_allocate
   \fi}

\def\page_columns_allocate
  {\dorecurse\nofcolumns
     {\ifnum\recurselevel>\allocatednofcolumns\relax
        \ifcsname\??columntext\recurselevel\endcsname \else
          \expandafter\newbox\csname\??columntext  \recurselevel\endcsname % text
          \expandafter\newbox\csname\??columnfooter\recurselevel\endcsname % footer
          \expandafter\newbox\csname\??columntop   \recurselevel\endcsname % top insert
          \expandafter\newbox\csname\??columnbottom\recurselevel\endcsname % bottom insert
        \fi
      \fi}%
   \global\allocatednofcolumns\nofcolumns}

\mutable  \def\currentcolumn      {1}

\permanent\def\firstcolumnbox     {\columntextbox\plusone}
\permanent\def\currentcolumnbox   {\columntextbox\mofcolumns}
\permanent\def\lastcolumnbox      {\columntextbox\nofcolumns}

\permanent\def\firsttopcolumnbox  {\columntopbox \plusone}
\permanent\def\currenttopcolumnbox{\columntopbox \mofcolumns}
\permanent\def\lasttopcolumnbox   {\columntopbox \nofcolumns}

\permanent\def\columntextbox#1{\csname\??columntext  \number#1\endcsname}
\permanent\def\columnfootbox#1{\csname\??columnfooter\number#1\endcsname}
\permanent\def\columntopbox #1{\csname\??columntop   \number#1\endcsname}
\permanent\def\columnbotbox #1{\csname\??columnbottom\number#1\endcsname}

\permanent\protected\def\columnsettextbox{\global\setbox\columntextbox}
\permanent\protected\def\columnsetfootbox{\global\setbox\columnfootbox}
\permanent\protected\def\columnsettopbox {\global\setbox\columntopbox}
\permanent\protected\def\columnsetbotbox {\global\setbox\columnbotbox}

\permanent\protected\def\columngettextbox    {\copy\columntextbox}
\permanent\protected\def\columngetfootbox    {\copy\columnfootbox}
\permanent\protected\def\columngettopbox     {\copy\columntopbox}
\permanent\protected\def\columngetbotbox     {\copy\columnbotbox}

\permanent\protected\def\columnerasetextboxes{\dorecurse\allocatednofcolumns{\columnsettextbox\recurselevel\emptybox}}
\permanent\protected\def\columnerasefootboxes{\dorecurse\allocatednofcolumns{\columnsetfootbox\recurselevel\emptybox}}
\permanent\protected\def\columnerasetopboxes {\dorecurse\allocatednofcolumns{\columnsettopbox \recurselevel\emptybox}}
\permanent\protected\def\columnerasebotboxes {\dorecurse\allocatednofcolumns{\columnsetbotbox \recurselevel\emptybox}}

%D Without going in details we present two macro's which handle the columns. The
%D action which is transfered by the the first and only parameter can do something
%D with \type {\currentcolumnbox}. In case of the mid columns, \type
%D {\firstcolumnbox} and \type {\lastcolumnbox} are handled outside these macro's.

\let\page_columns_action\relax

\permanent\protected\def\dohandleallcolumnscs#1{\let\page_columns_action  #1\page_columns_all_indeed}
\permanent\protected\def\dohandleallcolumns  #1{\def\page_columns_action{#1}\page_columns_all_indeed}

\permanent\protected\def\dohandlerevcolumnscs#1{\let\page_columns_action  #1\page_columns_rev_indeed}
\permanent\protected\def\dohandlerevcolumns  #1{\def\page_columns_action{#1}\page_columns_rev_indeed}

\permanent\protected\def\dohandlemidcolumnscs#1{\let\page_columns_action  #1\page_columns_mid_indeed}
\permanent\protected\def\dohandlemidcolumns  #1{\def\page_columns_action{#1}\page_columns_mid_indeed}

\protected\def\page_columns_all_indeed
  {\mofcolumns\plusone
   \edef\currentcolumn{\the\mofcolumns}%
   \page_columns_action\relax
   \ifnum\mofcolumns<\nofcolumns
     \expandafter\page_columns_all_next
   \fi}

\protected\def\page_columns_all_next
  {\advanceby\mofcolumns\plusone
   \edef\currentcolumn{\the\mofcolumns}%
   \page_columns_action\relax
   \ifnum\mofcolumns<\nofcolumns
     \expandafter\page_columns_all_next
   \fi}

\protected\def\page_columns_rev_indeed
  {\mofcolumns\nofcolumns
   \edef\currentcolumn{\the\mofcolumns}%
   \page_columns_action\relax
   \ifnum\mofcolumns>\plusone
     \expandafter\page_columns_rev_prev
   \fi}

\protected\def\page_columns_rev_prev
  {\advanceby\mofcolumns\minusone
   \edef\currentcolumn{\the\mofcolumns}%
   \page_columns_action\relax
   \ifnum\mofcolumns>\plusone
     \expandafter\page_columns_rev_prev
   \fi}

\protected\def\page_columns_mid_indeed
  {\mofcolumns\plustwo
   \ifnum\mofcolumns<\nofcolumns
     \expandafter\page_columns_mid_next
   \fi}

\protected\def\page_columns_mid_next
  {\edef\currentcolumn{\the\mofcolumns}%
   \page_columns_action\relax
   \advanceby\mofcolumns\plusone
   \ifnum\mofcolumns<\nofcolumns
     \expandafter\page_columns_mid_next
   \fi}

\protect \endinput