%D \module
%D   [       file=core-two, % moved from core-uti
%D        version=1997.03.31,
%D          title=\CONTEXT\ Core Macros,
%D       subtitle=Two Pass Data,
%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 Core Macros / Two Pass Data}

%D This is a rather old mechanism which has not changed much over
%D time, apart from adding a few more selectors. This code used
%D to be part of \type {core-uti}. The following examples demonstrate
%D the interface.
%D
%D \startbuffer
%D \definetwopasslist{test-1}
%D
%D \gettwopassdatalist{test-1} [\twopassdatalist=]
%D \checktwopassdata  {test-1} [\twopassdata=]
%D \checktwopassdata  {test-1} [\twopassdata=]
%D \gettwopassdata    {test-1} [\twopassdata=]
%D \gettwopassdata    {test-1} [\twopassdata=]
%D
%D \definetwopasslist{test-2}
%D
%D \lazysavetwopassdata{test-2}{1}{x}
%D \lazysavetwopassdata{test-2}{2}{y}
%D \lazysavetwopassdata{test-2}{3}{z}
%D
%D \gettwopassdatalist{test-2} [\twopassdatalist=x,y,z]
%D \checktwopassdata  {test-2} [\twopassdata=x]
%D \checktwopassdata  {test-2} [\twopassdata=x]
%D \gettwopassdata    {test-2} [\twopassdata=x]
%D \gettwopassdata    {test-2} [\twopassdata=y]
%D \gettwopassdata    {test-2} [\twopassdata=z]
%D \gettwopassdata    {test-2} [\twopassdata=]
%D
%D \definetwopasslist{test-3}
%D
%D \lazysavetaggedtwopassdata{test-3}{1}{x}{a}
%D \lazysavetaggedtwopassdata{test-3}{2}{y}{b}
%D \lazysavetaggedtwopassdata{test-3}{3}{z}{c}
%D
%D \findtwopassdata{test-3}{x} [\twopassdata=a]
%D \findtwopassdata{test-3}{y} [\twopassdata=b]
%D \findtwopassdata{test-3}{z} [\twopassdata=c]
%D \findtwopassdata{test-3}{w} [\twopassdata=]
%D
%D \definetwopasslist{test-4}
%D
%D \lazysavetwopassdata{test-4}{1}{A}
%D \lazysavetwopassdata{test-4}{2}{B}
%D \lazysavetwopassdata{test-4}{3}{C}
%D
%D \getfirsttwopassdata{test-4}    [\twopassdata=A]
%D \getlasttwopassdata {test-4}    [\twopassdata=C]
%D \getfirsttwopassdata{test-4}    [\twopassdata=A]
%D \getlasttwopassdata {test-4}    [\twopassdata=C]
%D \getfromtwopassdata {test-4}{1} [\twopassdata=A]
%D \getfromtwopassdata {test-4}{3} [\twopassdata=C]
%D \getfromtwopassdata {test-4}{2} [\twopassdata=B]
%D \stopbuffer
%D
%D \getbuffer \typebuffer

\unprotect

\let\alltwopasslists\empty
\let\twopassentry   \gobblethreearguments % permits loading a MK II file
\let\twopassdata    \empty
\let\twopassdatalist\empty

\newif\iftwopassdatafound

\addutilityreset{twopassentries}

\def\immediatesavetwopassdata   #1#2#3{\immediatewriteutilitycommand{\twopassentry{#1}{#2}{#3}}}
\def\savetwopassdata            #1#2#3{\writeutilitycommand{\twopassentry{#1}{#2}{#3}}}
\def\lazysavetwopassdata        #1#2#3{\expanded{\writeutilitycommand{\noexpand\twopassentry{#1}{#2}{#3}}}} % expanded !
\def\savetaggedtwopassdata    #1#2#3#4{\immediatewriteutilitycommand{\twopassentry{#1}{#2}{#3::#4}}}
\def\lazysavetaggedtwopassdata#1#2#3#4{\expanded{\writeutilitycommand{\noexpand\twopassentry{#1}{#2}{#3::#4}}}} % expanded !

\def\resettwopassentries
  {\let\twopassentry\gobblethreearguments}

\def\settwopassentries
  {\def\twopassentry##1{\executeifdefined{@@##1\s!pass}\gobbletwoarguments}}

\resettwopassentries

\def\appendtwopasselement#1#2#3% can sometimes become a large list
  {%\debuggerinfo{\m!systems}{twopass data #1 - #2 = #3}%
   \expandafter\xdef\csname#1:\s!list\endcsname
     {\@EA\ifx\csname#1:\s!list\endcsname\empty \else
        \csname#1:\s!list\endcsname,\fi#3}}

\def\dodefinetwopasslist#1%
  {\doifundefined{#1:\s!list}
     {%\debuggerinfo\m!systems{defining twopass class #1}%
      \doglobal\addutilityreset{#1\s!pass}%
      \setgvalue{\s!set  #1\s!pass}{\dosettwopasslist  {#1}}%
      \setgvalue{\s!reset#1\s!pass}{\doresettwopasslist{#1}}%
      \getvalue {\s!reset#1\s!pass}}}

\def\definetwopasslist#1%
  {\expanded{\dodefinetwopasslist{#1}}%
   \doglobal\addtocommalist{#1}\alltwopasslists}

\def\dosettwopasslist#1%
  {\letgvalue{\s!set#1\s!pass}\gobbletwoarguments
   \setgvalue{@@#1\s!pass}{\appendtwopasselement{#1}}}

\def\doresettwopasslist#1%
  {\letgvalue{@@#1\s!pass}\gobbletwoarguments}

\def\doloadtwopassdata#1%
  {\doifundefined{#1:\s!list}
     {\startnointerference
      \letgvalueempty{#1:\s!list}%
      \protectlabels
      \doutilities{twopassentries,#1\s!pass}\jobname\empty\relax\relax
      \stopnointerference}}

\def\loadtwopassdata
  {\ifx\alltwopasslists\empty\else
     \processcommacommand[\alltwopasslists]\doloadtwopassdata
     \globallet\alltwopasslists\empty
   \fi}

\def\dogettwopassdata[#1,#2]#3#4%
  {\edef\twopassdata{#1}%
   \ifx\twopassdata\empty
     \twopassdatafoundfalse
     \let\twopassdata\empty
   \else
     \twopassdatafoundtrue
     \ifcase#4\or\setxvalue{#3:\s!list}{#2}\fi
   \fi}

\def\gettwopassdata#1%
  {\loadtwopassdata \@EAEAEA\dogettwopassdata\@EA\@EA\@EA[\csname#1:\s!list\endcsname,]{#1}\plusone}

\def\checktwopassdata#1%
  {\loadtwopassdata \@EAEAEA\dogettwopassdata\@EA\@EA\@EA[\csname#1:\s!list\endcsname,]{#1}\zerocount}

\def\findtwopassdata#1#2%
  {\loadtwopassdata \expanded{\dofindtwopassdata{#1}{#2}}}

\def\dofindtwopassdata#1#2%
  {\def\dodofindtwopassdata[##1,##2#2::##3,##4]{\edef\twopassdata{##3}}%
   \@EAEAEA\dodofindtwopassdata\@EA\@EA\@EA[\@EA\@EA\@EA,\csname#1:\s!list\endcsname,#2,#2::,]%
   \ifx\twopassdata\empty
     \twopassdatafoundfalse
   \else
     \twopassdatafoundtrue
   \fi}

\let\getfirsttwopassdata\checktwopassdata

\def\getlasttwopassdata#1%
  {\loadtwopassdata
   \scratchcounter\zerocount
   \@EAEAEA\rawprocesscommalist\@EA\@EA\@EA[\csname#1:\s!list\endcsname]\dogetlasttwopassdata
   \edef\noftwopassitems{\the\scratchcounter}%
   \iftwopassdatafound\else
     \let\twopassdata\empty
   \fi}

\def\dogetlasttwopassdata#1%
  {\edef\nexttwopassdata{#1}%
   \ifx\nexttwopassdata\empty \else
     \let\twopassdata\nexttwopassdata
     \advance\scratchcounter \plusone
     \twopassdatafoundtrue
   \fi}

\def\getfromtwopassdata#1#2%
  {\loadtwopassdata
   \@EAEAEA\getfromcommalist\@EA\@EA\@EA[\csname#1:\s!list\endcsname][#2]%
   \ifx\commalistelement\empty
     \twopassdatafoundfalse
     \let\twopassdata\empty
   \else
     \twopassdatafoundtrue
     \let\twopassdata\commalistelement
   \fi}

\def\gettwopassdatalist#1%
  {\loadtwopassdata
   \letcscsname\twopassdatalist\csname#1:\s!list\endcsname
   \ifx\twopassdatalist\relax\let\twopassdatalist\empty\fi}

\def\gettwopassdatalist
  {\getnamedtwopassdatalist\twopassdatalist}

\def\doifelseintwopassdata#1#2% tag dat
  {\gettwopassdatalist{#1}%
   \expanded{\doifinsetelse{#2}{\twopassdatalist}}}

\protect \endinput