% \iffalse meta-comment
%
% Copyright 1994 the LaTeX3 project and the individual authors.
% All rights reserved. For further copyright information see the file
% legal.txt, and any other copyright indicated in this file.
% 
% This file is part of the LaTeX2e system.
% ----------------------------------------
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%  This system is distributed in the hope that it will be useful,
%  but WITHOUT ANY WARRANTY; without even the implied warranty of
%  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
% 
% 
% IMPORTANT NOTICE:
% 
% For error reports in case of UNCHANGED versions see bugs.txt.
% 
% Please do not request updates from us directly.  Distribution is
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% You are allowed to distribute this file under the condition that
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% You are NOT ALLOWED to distribute this file alone.  You are NOT
% ALLOWED to take money for the distribution or use of either this
% file or a changed version, except for a nominal charge for copying
% etc.
% \fi
%
% \iffalse
%%% File: ltcntrl.dtx
%<*driver>
% \fi
\ProvidesFile{ltcntrl.dtx}
             [1994/05/16 v1.1a LaTeX Kernel (program control)]
% \iffalse
\documentclass{ltxdoc}
\GetFileInfo{ltcntrl.dtx}
\title{\filename}
\date{\filedate}
 \author{%
  Johannes Braams\and
  David Carlisle\and
  Alan Jeffrey\and
  Leslie Lamport\and
  Frank Mittelbach\and
  Chris Rowley\and
  Rainer Sch\"opf}
\begin{document}
\maketitle
 \DocInput{\filename}
\end{document}
%</driver>
% \fi
%
% \CheckSum{202}
%
% \changes{v1.1a}{1994/05/16}{(ASAJ) Split from ltinit.dtx.}
%
% \section{Program control structure}
% 
% This section defines a number of control structure macros, such as
% while-loops and for-loops.
%
% \StopEventually{}
%
% \begin{oldcomments}
%    \begin{macrocode}
%<*2ekernel>
\message{control,}
%    \end{macrocode}
%      **********************************************
%      *     PROGRAM CONTROL STRUCTURE MACROS       *
%      **********************************************
%
% \@whilenum TEST \do {BODY}
% \@whiledim TEST \do {BODY}  : These implement the loop
%           while  TEST  do  BODY  od
%     where  TEST  is a TeX \ifnum or \ifdim test, respectively.
%     They are optimized for the normal case of TEST initially false.
%
% \@whilesw SWITCH \fi {BODY} : Implements the loop
%               while SWITCH do BODY od
%     where SWITCH is a command defined by \newswitch.
%     Optimized for normal case of SWITCH initially false.
%
% \@for NAME := LIST \do {BODY} : Assumes that LIST expands to A1,A2,
%      ... ,An . 
%      Executes  BODY  n  times, with  NAME = Ai  on the i-th iteration.
%      Optimized for the normal case of n = 1.  Works for n=0.
%
% \@tfor NAME := LIST \do {BODY}
%      if, before expansion, LIST = T1 ... Tn  where each Ti is a
%      token or {...}, then executes  BODY  n  times, with  NAME = Ti
%      on the i-th iteration.  Works for n=0.
%
%  NOTES: 1. These macros use no \@temp sequences.
%         2. These macros do not work if the body contains anything that
%         looks syntactically to TeX like an improperly balanced \if
%         \else \fi. 
%
% \@whilenum TEST \do {BODY} ==
%  BEGIN
%    if  TEST
%      then  BODY
%            \@iwhilenum{TEST \relax BODY}
%  END
%
% \@iwhilenum {TEST BODY} ==
%  BEGIN
%    if  TEST
%      then  BODY
%            \@nextwhile = def(\@iwhilenum)
%      else  \@nextwhile = def(\@whilenoop)
%    fi
%    \@nextwhile {TEST BODY}
%  END
%
% \@whilesw SWITCH \fi {BODY} ==
%  BEGIN
%    if SWITCH
%      then BODY
%           \@iwhilesw {SWITCH BODY}\fi
%    fi
%  END
%
% \@iwhilesw {SWITCH BODY} \fi ==
%  BEGIN
%    if SWITCH
%      then BODY
%           \@nextwhile = def(\@iwhilesw)
%      else \@nextwhile = def(\@whileswnoop)
%    fi
%    \@nextwhile {SWITCH BODY} \fi
%  END
%
%    \begin{macrocode}
\def\@whilenoop#1{}
\def\@whilenum#1\do #2{\ifnum #1\relax #2\relax\@iwhilenum{#1\relax
     #2\relax}\fi}
\def\@iwhilenum#1{\ifnum #1\let\@nextwhile\@iwhilenum
         \else\let\@nextwhile\@whilenoop\fi\@nextwhile{#1}}
%    \end{macrocode}
%
%    \begin{macrocode}
\def\@whiledim#1\do #2{\ifdim #1\relax#2\@iwhiledim{#1\relax#2}\fi}
\def\@iwhiledim#1{\ifdim #1\let\@nextwhile\@iwhiledim
        \else\let\@nextwhile\@whilenoop\fi\@nextwhile{#1}}
%    \end{macrocode}
%
%    \begin{macrocode}
\long\def\@whileswnoop#1\fi{}
\long\def\@whilesw#1\fi#2{#1#2\@iwhilesw{#1#2}\fi\fi}
\long\def\@iwhilesw#1\fi{#1\let\@nextwhile\@iwhilesw
         \else\let\@nextwhile\@whileswnoop\fi\@nextwhile{#1}\fi}
%    \end{macrocode}
%
% \@for NAME := LIST \do {BODY} ==
%    BEGIN \@forloop expand(LIST),\@nil,\@nil \@@ NAME {BODY} END
%
% \@forloop CAR, CARCDR, CDRCDR \@@ NAME {BODY} ==
%   BEGIN
%     NAME = CAR
%     if def(NAME) = def(\@nnil)
%       else BODY;
%            NAME = CARCDR
%            if def(NAME) = def(\@nnil)
%              else BODY
%                   \@iforloop CDRCDR \@@ NAME \do {BODY}
%            fi
%     fi
%   END
%
% \@iforloop CAR, CDR \@@ NAME {BODY} =
%     NAME = CAR
%     if def(NAME) = def(\@nnil)
%        then  \@nextwhile = def(\@fornoop)
%        else  BODY ;
%              \@nextwhile = def(\@iforloop)
%     fi
%     \@nextwhile name cdr {body}
%
% \@tfor NAME := LIST \do {BODY}
%    =  \@tforloop LIST \@nil \@@ NAME {BODY}
%
% \@tforloop car cdr \@@ name {body} =
%     name = car
%     if def(name) = def(\@nnil)
%        then  \@nextwhile == \@fornoop
%        else  body ;
%              \@nextwhile == \@forloop
%     fi
%     \@nextwhile name cdr {body}
%
%    \begin{macrocode}
\def\@nnil{\@nil}
\def\@empty{}
\def\@fornoop#1\@@#2#3{}
%    \end{macrocode}
%
%    \begin{macrocode}
\def\@for#1:=#2\do#3{\edef\@fortmp{#2}\ifx\@fortmp\@empty \else
    \expandafter\@forloop#2,\@nil,\@nil\@@#1{#3}\fi}
%    \end{macrocode}
%
%    \begin{macrocode}
\def\@forloop#1,#2,#3\@@#4#5{\def#4{#1}\ifx #4\@nnil \else
       #5\def#4{#2}\ifx #4\@nnil \else#5\@iforloop #3\@@#4{#5}\fi\fi}
%    \end{macrocode}
%
%    \begin{macrocode}
\def\@iforloop#1,#2\@@#3#4{\def#3{#1}\ifx #3\@nnil
       \let\@nextwhile\@fornoop \else
      #4\relax\let\@nextwhile\@iforloop\fi\@nextwhile#2\@@#3{#4}}
%    \end{macrocode}
% \end{oldcomments}
%
% \begin{macro}{\@tfor}
% \changes{LaTeX209}{1991/10/17}
%         {(Rms) \cmd{\xdef} replaced by \cmd{\def} 
%          (See FMi's array.doc)}
% \changes{v1.0c}{1994/03/13}
%         {(DPC) Add \cmd{\@tf@r} so a single group is
%           correctly treated.}
%    \begin{macrocode}
\def\@tfor#1:={\@tf@r#1 }
\def\@tf@r#1#2\do#3{\def\@fortmp{#2}\ifx\@fortmp\space\else
    \@tforloop#2\@nil\@nil\@@#1{#3}\fi}
\def\@tforloop#1#2\@@#3#4{\def#3{#1}\ifx #3\@nnil
       \let\@nextwhile\@fornoop \else
      #4\relax\let\@nextwhile\@tforloop\fi\@nextwhile#2\@@#3{#4}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@break@tfor}
% Break out of a |\@tfor| loop. This should be called \emph{inside}
% the scope of an |\if|. See |\@iffileonpath| for an example.
% \changes{v1.0l}{1994/05/02}{Macro added (from ltfiles.dtx)}
%    \begin{macrocode}
\def\@break@tfor#1\@@#2#3{\fi\fi}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@removeelement}
%
% Removes an element from a comma-separated list and put the result in 
% a control sequence, called as 
% |\@removeelement{|\meta{element}|}{|\meta{list}|}{|\meta{cs}|}|.
%
%  Added |\ifx,| to remove extra |,|'s.
%    \begin{macrocode}
\def\@removeelement#1#2#3{%
  \def\@tempa##1,#1,##2\@tempa{##1,##2\@tempb}%
  \def\@tempb##1,\@tempb##2\@tempb{\ifx,##1\@empty\else##1\fi}%
  \edef#3{\expandafter\@tempb\@tempa,#2,\@tempb,#1,\@tempa}}
%    \end{macrocode}
% \end{macro}
%
%    \begin{macrocode}
\let\protect=\relax
%    \end{macrocode}
%
%    \begin{macrocode}
\def\@setprotect{%
  \let\@@protect\protect
  \def\protect{\noexpand\protect\noexpand}}
\def\@resetprotect{\let\protect\@@protect}
%</2ekernel>
%    \end{macrocode}
%
%\Finale
\endinput

