%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 / Hans Hagen \& Ton Otten}]
%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   \empty
\let\twopassdata    \empty
\let\twopassdatalist\empty

\newif\iftwopassdatafound

\let\savetwopassdata          \gobblethreearguments
\let\immediatesavetwopassdata \gobblethreearguments
\let\lazysavetwopassdata      \gobblethreearguments
\let\savetaggedtwopassdata    \gobblefourarguments
\let\lazysavetaggedtwopassdata\gobblefourarguments

\let\twopassentry   \gobblethreearguments % permits loading a MK II file
\let\loadtwopassdata\relax                % permits loading a MK II file

\let\definetwopasslist\gobbleoneargument

\def\gettwopassdata           #1{\let\twopassdata    \empty \twopassdatafoundfalse}
\def\checktwopassdata         #1{\let\twopassdata    \empty \twopassdatafoundfalse}
\def\findtwopassdata        #1#2{\let\twopassdata    \empty \twopassdatafoundfalse}
\def\getlasttwopassdata       #1{\let\twopassdata    \empty \twopassdatafoundfalse}
\def\getfromtwopassdata     #1#2{\let\twopassdata    \empty \twopassdatafoundfalse}
\def\gettwopassdatalist       #1{\let\twopassdatalist\empty \twopassdatafoundfalse}
\def\getnamedtwopassdatalist#1#2{\let#1              \empty \twopassdatafoundfalse}
\def\doifelseintwopassdata  #1#2{\secondoftwoarguments}

\loadmarkfile{core-two}

\protect \endinput