%D \module
%D   [       file=java-ini,
%D        version=1998.01.30,
%D          title=\CONTEXT\ JavaScript Macros,
%D       subtitle=Initialization,
%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 JavaScript Macros / Initialization}

% BUG: preamble zonder used/used en split

% JavaScript support is under development. In the near future
% a slightly different model will be used. The JScode stuff
% will probably become just auto function inclusion and the
% JS_* things will disappear. First I have to find a way to
% deal with global variables so the 'uses' thing will remain.

% ook p{ref}
% documentation should be corrected to JS(

% Also, obeylines will be supported.

\unprotect

%D \JAVA\ support is not implemented as a generic support
%D module. The main reason for this is that passing system
%D variables to a \JAVASCRIPT\ is closely related to other core
%D macros. First some messages:

\startmessages  dutch  library: javascript
  title: javascript
      1: script set -- wordt geladen
      2: onbekende preamble --
\stopmessages

\startmessages  english  library: javascript
  title: javascript
      1: loading script set --
      2: unknown preamble --
\stopmessages

\startmessages  german  library: javascript
  title: javascript
      1: Lade Scriptdatei --
      2: unbekannte Preamble --
\stopmessages

\startmessages  czech  library: javascript
  title: javascript
      1: nacita se soubor skriptu --
      2: neznama preambule --
\stopmessages

\startmessages  italian  library: javascript
  title: javascript
      1: caricamento dello script set --
      2: preambolo sconosciuto --
\stopmessages

\startmessages  norwegian library: javascript
  title: javascript
      1: leser inn scriptsett --
      2: ukjent 'preamble' --
\stopmessages

\startmessages  romanian  library: javascript
  title: javascript
      1: se incarca scriptul --
      2: preambul necunoscut --
\stopmessages

%D \TEX\ is not the right tool to check the \JAVA\ code; the
%D most we can do is reporting some passed variables:

\newif\iftraceJScode \traceJScodefalse

\let\traceJScode\traceJScodetrue

%D A bit out of place, but not dangerous:

\bgroup
\catcode127=\@@letter
\gdef\delcharacter{^^7f}
\egroup

%D The number of passed variables is minimalized by setting the
%D next switch.

\newif\ifminimalizeJScode    \minimalizeJScodetrue

%D \macros
%D   {JS*}
%D
%D Because \JAVASCRIPT's are activated by the user, for
%D instance by activating on a button, their support is closely
%D related to the referencing mechanism. Integration takes
%D place by
%D
%D \starttyping
%D \goto{calculate total}[Sum()]
%D \stoptyping
%D
%D The \type{()} classify this as a script. If they are absent,
%D the keyword is treated as a normal reference.
%D
%D One can pass arguments to such a script by saying:
%D
%D \starttyping
%D \goto{calculate total}[Sum(1.5,2.3)]
%D \stoptyping
%D
%D References are passed by using the \type{R{}} classifier.
%D
%D \starttyping
%D \goto{calculate total}[Sum(1.5,2.3,R{overflow})]
%D \stoptyping
%D
%D The last call calls the script \type{Sum} and passes the
%D next set of variables:
%D
%D \starttyping
%D JS_S_1="1.5";
%D JS_S_2="2.3";
%D JS_R_3="overflow";
%D JS_P_3=3;
%D \stoptyping
%D
%D The first two parameters are just strings, the third one
%D however is treated as a reference and results in passing the
%D reference (if needed this references is prefixed) and the
%D (real) page number. The alternative:
%D
%D \starttyping
%D \goto{calculate total}[JS(Sum{V{1.5},V{2.3},R{overflow}})]
%D \stoptyping
%D
%D does a verbose passing:
%D
%D \starttyping
%D JS_V_1=1.5;
%D JS_V_2=2.3;
%D JS_R_3="overflow";
%D JS_P_3=3;
%D \stoptyping
% %D
% %D Finally we have a counter that tells\JAVA\ how many
% %D arguments were passed,
% %D
% %D \starttyping
% %D JS_N
% %D \stoptyping

%D We will also support direct function calls. In that case
%D no intermediate variables are used.

%D \macros
%D   {startJScode}
%D
%D A piece of \JAVASCRIPT\ code is defined by saying:
%D
%D \starttyping
%D \startJScode{SomeScript}
%D   var Item=this.getField("item");
%D          N=Item.getArray();
%D      Total=this.getField("total");
%D   Total.value=0;
%D   for (j=0; j<N.length; j++)
%D     { if (N[j].value!="")
%D       { Total.value += N[j].value } } ;
%D   if ((JS_N>0) && (JS_R_1!=""))
%D     { gotoNamedDest(JS_R_1) };
%D \stopJScode
%D \stoptyping
%D
%D Such a piece of code is closely related to the interpreter
%D used. Watch the last two lines, here the script adapts
%D itself to the presence of a reference.
%D
%D While
%D
%D \starttyping
%D \startJScode{name}
%D   name = 4 ;
%D \stopJScode
%D \stoptyping
%D
%D assumes uses no preamble or presumes that the preamble is
%D always loaded, the next definition also tells \CONTEXT\ to
%D actually include the preamble needed.
%D
%D \starttyping
%D \startJScode{uses} uses {later}
%D   uses = 6 ;
%D \stopJScode
%D \stoptyping

\long\def\startJScode#1 #2
  {\doifelse{#2}{uses}
     {\dostartJScodeA{#1}}
     {\dostartJScodeB{#1} #2 }}

\long\def\dostartJScodeA#1#2 #3\stopJScode
  {\long\setgvalue{\r!java#1}{\do{#2}{#3}}}

\long\def\dostartJScodeB#1#2\stopJScode
  {\long\setgvalue{\r!java#1}{\do{}{#2}}}

\let\stopJScode\relax

%D \macros
%D   {presetJScode}
%D
%D The code can be retrieved by saying
%D
%D \starttyping
%D \presetJScode{SomeScript}{template}
%D \stoptyping
%D
%D Such a template is a comma separated list, where
%D individual entries can optionally be transformed by
%D \type{R{}} and \type{V{}}.
%D
%D After this call, the code is available in \type{\JScode}.

\def\setverbosecscharacter#1%
  {\edef#1{\string#1}}

\def\setverbosecscharacters % temporary hack
  {\setverbosecscharacter |\setverbosecscharacter ~%
   \setverbosecscharacter\:\setverbosecscharacter\;%
   \setverbosecscharacter\+\setverbosecscharacter\-%
   \setverbosecscharacter\[\setverbosecscharacter\]%
   \setverbosecscharacter\.\setverbosecscharacter\\%
   \setverbosecscharacter\)\setverbosecscharacter\(%
   \setverbosecscharacter\0\setverbosecscharacter\1%
   \setverbosecscharacter\2\setverbosecscharacter\3%
   \setverbosecscharacter\4\setverbosecscharacter\5%
   \setverbosecscharacter\6\setverbosecscharacter\7%
   \setverbosecscharacter\8\setverbosecscharacter\9%
   \setverbosecscharacter\n\setverbosecscharacter\s%
   \setverbosecscharacter\/}

\newif\ifdirectJScode

\def\presetJScode#1#2% #1=operation #2=arguments
  {\setverbosecscharacters
   \def\par{\delcharacter}% was: { }
   \scratchcounter\zerocount
   \globallet\JScode\empty
   \def\do##1##2%
     {\doifelse{##2}{!}\directJScodetrue\directJScodefalse}%
   \getvalue{\r!java#1}%
   \edef\!!stringa{#2}%
   \ifx\!!stringa\empty \else
     \processcommacommand[\!!stringa]\dopresetJSvariables
   \fi
   \def\docommando##1%
     {\doifundefinedelse{\r!java\r!java##1}
        {\showmessage\m!javascript2{##1}}
        {\useJSpreamblenow{##1}}}%
%        {\doglobal\increment\currentJSpreamble
%         \doglobal\addtocommalist{##1}\allJSpreambles}}%
   \def\do##1##2%
     {\xdef\JScode{\ifdirectJScode#1(\JScode)\else\JScode##2\fi}%
     %\xdef\JScode{JS\string_N=\the\scratchcounter;\JScode}%
      \processcommalist[##1]\docommando}%
   \getvalue{\r!java#1}}

\def\dopresetJSvariables#1%
  {\advance\scratchcounter \plusone
   \donefalse
   \dodopresetJSvariables#1\end}%

\def\dodopresetJSvariables
  {\doifnextcharelse R\dodopresetJSrefvariables
  {\doifnextcharelse V\dodopresetJSvervariables
  {\doifnextcharelse S\dodopresetJSstrvariables
                      \dodopresetJSrawvariables}}}

\def\dodopresetJSrefvariables R#1\end
  {\doifreferencefoundelse{#1}
     {\donetrue \dododopresetJSvariables R{\referenceprefix#1}%
      \donefalse\dododopresetJSvariables P{\currentrealreference}}
     {\unknownreference{#1}}%
   \ifminimalizeJScode \else
     \donetrue\dododopresetJSvariables S{#1}%
   \fi}

\def\dodopresetJSvervariables V#1\end
  {\donefalse\dododopresetJSvariables V{#1}%
   \ifminimalizeJScode \else
     \donetrue\dododopresetJSvariables S{#1}%
   \fi}

\def\dodopresetJSstrvariables S#1\end
  {\donetrue\dododopresetJSvariables S{#1}}

\def\dodopresetJSrawvariables #1\end
  {\donetrue\dododopresetJSvariables S{#1}}

\def\JSprefix#1%
  {JS\string_#1\string_\the\scratchcounter}

\def\dododopresetJSvariables#1#2%
  {\iftraceJScode
     \writestatus{JavaScript}{\JSprefix#1=#2}
     \xdef\JScode{\JScode console.println("\JSprefix#1=#2"); }%
   \fi
   \ifdirectJScode
     \xdef\JScode{\ifx\JScode\empty\else\JScode,\fi\ifdone"#2"\else#2\fi}%
   \else
     \xdef\JScode{\JScode\JSprefix#1=\ifdone"#2"\else#2\fi; }%
   \fi}

%D \macros
%D   {startJSpreamble, flushJSpreamble}
%D
%D One can define insert \JAVASCRIPT\ code at the document level
%D by using:
%D
%D \starttyping
%D \startJSpreamble{oeps}
%D   oeps = 1 ;
%D \stopJSpreamble
%D \stoptyping
%D
%D which is the same as:
%D
%D \starttyping
%D \startJSpreamble{now} used now
%D   now = 2 ;
%D \stopJSpreamble
%D \stoptyping
%D
%D while the next definition is only included when actually
%D used.
%D
%D \starttyping
%D \startJSpreamble{later} used later
%D   later = 3 ;
%D \stopJSpreamble
%D \stoptyping
%D
%D This command may be used more that once, but always before
%D the first page is shipped out.

\newif\ifoneJSpreamble \oneJSpreamblefalse

\let\allJSpreambles\empty
\newcounter\nofJSpreambles
\newcounter\currentJSpreamble

\long\def\startJSpreamble#1 #2 %
  {\bgroup           % we need to restore the catcodes
   \restoreendofline % just in case it happens while reading lists
   \doifelse{#2}{used}
     {\dostartJSpreamble#1 }
     {\dostartJSpreamble#1 now #2 }}

\long\def\dostartJSpreamble#1 #2 %
  {\processaction
     [#2]
     [     later=>\chardef\JSstatus\zerocount,%
             now=>\chardef\JSstatus\plusone  ,%
      \s!default=>\chardef\JSstatus\plustwo  ,%
      \s!unknown=>\chardef\JSstatus\plustwo  ]%
    \ifaddJSlinebreaks
      \obeylines  \let\obeyedline \normalpar
      \obeyspaces \let\obeyedspace\normalspace
    \fi
    \dodostartJSpreamble{#1}}

\long\def\dodostartJSpreamble#1#2\stopJSpreamble
  {\presetJSfunctions #2function ()\end
   \long\setgvalue{\r!java\r!java#1}{#2}%
   \ifcase\JSstatus \else
     \useJSpreamblenow{#1}%
   \fi
   \egroup}

%D \macros
%D   {setJSpreamble, addtoJSpreamble}
%D
%D In addition to the previous preamble definitions, we can
%D set a preamble \quote {in||line} and add tokens to a
%D preamble.

\def\setJSpreamble#1#2%
  {\doifundefined{\r!java\r!java#1}
     {\setgvalue{\r!java\r!java#1}{#2;}%
      \doglobal\increment\currentJSpreamble
      \doglobal\addtocommalist{#1}\allJSpreambles}}

\def\addtoJSpreamble#1#2%
  {\doifdefinedelse{\r!java\r!java#1}
     {\edef\!!stringa{\r!java\r!java#1}%
      \edef\!!stringb{\csname\!!stringa\endcsname}%
      \@EA\setgvalue\@EA\!!stringa\@EA{\!!stringb #2;}}
     {\setJSpreamble{#1}{#2}}}

%D \macros
%D   {useJSpreamblenow}
%D
%D The next macro can be used to force inclusion of postponed
%D \JAVASCRIPT\ preambles.

\def\useJSpreamblenow#1%
  {\doglobal\increment\currentJSpreamble
   \doglobal\addtocommalist{#1}\allJSpreambles}

%D Because we want to check for valid calls, we preload the
%D functions. This means that we can call them directly as
%D well as indirectly when defined by \type {\startJScode} etc.

% \long\def\presetJSfunctions#1function #2(#3)%
%   {\doifelsenothing{#2}
%      {\long\def\presetJSfunctions##1\end{}}
%      {\stripspaces\from#2\to\ascii
%       \doifundefined{\r!java\ascii}{\setgvalue{\r!java\ascii}{\do{}{!}}}}%
%    \presetJSfunctions}

\long\def\presetJSfunctions#1function#2(#3)%
  {\doifelse{#2}\space
     {\long\def\presetJSfunctions##1\end{}}
     {\stripspaces\from#2\to\ascii
      \doifundefined{\r!java\ascii}{\setgvalue{\r!java\ascii}{\do{}{!}}}}%
   \presetJSfunctions}

\def\getJSpreamble#1%
  {\getvalue{\r!java\r!java#1}}

\def\presetJSpreamble
  {\ifx\allJSpreambles\empty\else
     \bgroup
     \setverbosecscharacters
     \def\par{\delcharacter}% was: { }
     \globallet\JSpreamble\empty
     \def\@@collectedJSpreamble{\r!java\r!java collected}%
     \letvalue{\@@collectedJSpreamble}=\empty
     \def\docommando##1%
       {\xdef\JScode{\getvalue{\r!java\r!java##1}}%
        \ifoneJSpreamble % \global\letcdcsname
          \@EA\setxvalue\@EA\@@collectedJSpreamble\@EA
            {\csname\@@collectedJSpreamble\endcsname\JScode}%
        \else
          \setxvalue{\r!java\r!java##1}{\JScode}%
        \fi}%
     \processcommacommand[\allJSpreambles]\docommando
     \ifoneJSpreamble
       \gdef\allJSpreambles{collected}%
     \fi
     \globallet\presetJSpreamble\relax
     \egroup
   \fi}

\def\flushJSpreamble
  {\iflocation\ifx\allJSpreambles\empty\else
     \ifcase\nofJSpreambles\else\ifnum\nofJSpreambles=\currentJSpreamble
       \bgroup
       \presetJSpreamble
       \expanded{\doflushJSpreamble{\allJSpreambles}}%
       \globallet\flushJSpreamble\relax
       \globallet\allJSpreambles\empty
       \egroup
     \fi\fi
   \fi\fi}

\def\finalflushJSpreamble
  {\iflocation
     \flushJSpreamble
     \ifcase\currentJSpreamble\relax\else
       \savecurrentvalue\nofJSpreambles\currentJSpreamble
       \globallet\currentJSpreamble\nofJSpreambles
     \fi
   \fi}

\prependtoks \flushJSpreamble      \to \everyshipout
\prependtoks \finalflushJSpreamble \to \everylastshipout

%D \macros
%D   {doPSsanitizeJScode}
%D
%D Before the code can be passed to the (\POSTSCRIPT\ or \PDF)
%D output file, some precautions must be made concerning the
%D use of \type{(} and~\type{)}. Here we use a beautiful
%D \type{\aftergroup} trick I discovered in the \TABLE\ format.

\def\doPSsanitizeJScode#1\to#2%
  {\begingroup
   \scratchcounter\zerocount % \aftergroup counter
   \aftergroup\xdef
   \aftergroup#2%
   \aftergroup{%
   \expanded{\convertargument#1\noexpand\to\noexpand\JScode}%
   \expandafter\handletokens\JScode\with\dodoPSsanitizeJScode
   \aftergroup}%
   \endgroup
   \iftraceJScode
     \writestatus{JS trace}{#2}%
   \fi}

%D I started with:
%D
%D \starttyping
%D \def\dodoPSsanitizeJScode#1%
%D   {\aftergroup\string
%D    \if#1(%
%D      \expandafter\aftergroup\csname#1\endcsname
%D    \else\if#1)%
%D      \expandafter\aftergroup\csname#1\endcsname
%D    \else\if#1;%
%D      \aftergroup;\aftergroup\string\expandafter\aftergroup\
%D    \else
%D      \expandafter\aftergroup#1%
%D    \fi\fi\fi
%D    \advance\scratchcounter by 1
%D    \ifnum\scratchcounter=500
%D      \expandafter\dododoPSsanitizeJScode
%D    \fi}
%D \stoptyping
%D
%D For pretty printing purposes, we need some way to signal
%D \TEX\ macros. Therefore we introduce a special keyword
%D \type{TEX}. When followed by a space, this keyword is
%D ignored, that is, filtered from the stream. Now we have:

\chardef\JSisTEX  \zerocount
\chardef\JScomment\zerocount

\newif\ifaddJSlinebreaks \addJSlinebreakstrue

\def\flushJSisTEX
  {\ifcase\JSisTEX
   \or \aftergroup T%
   \or \aftergroup T\aftergroup E%
   \or \aftergroup T\aftergroup E\aftergroup X%
   \fi
   \chardef\JSisTEX\zerocount}

% \def\doJSlinebreak
%  {\ifaddJSlinebreaks
%     \aftergroup\string\aftergroup\n%
%   \fi}
%
% \def\dodoPSsanitizeJScode#1%  % input stack>500 & TEX check
%   {\if#1/%
%      \ifnum\JScomment=0
%        \chardef\JScomment\plusone
%      \else\ifnum\JScomment=1
%        \chardef\JScomment\plustwo
%      \fi\fi
%    \else
%      \ifnum\JScomment=1
%        \aftergroup/%
%        \chardef\JScomment\zerocount
%      \fi
%      \ifnum\JScomment=2
%        \if#1\delcharacter
%          \chardef\JScomment\zerocount
%        \fi
%      \else
%        \if#1\delcharacter
%          \flushJSisTEX\doJSlinebreak
%        \else\if#1(%
%          \flushJSisTEX\aftergroup\string\expandafter\aftergroup\csname#1\endcsname
%        \else\if#1)%
%          \flushJSisTEX\aftergroup\string\expandafter\aftergroup\csname#1\endcsname
%        \else\if#1;%
%          \flushJSisTEX\aftergroup;\doJSlinebreak
%        \else\if#1T%
%          \ifnum\JSisTEX=0 \chardef\JSisTEX\plusone   \else\flushJSisTEX\aftergroup T\fi
%        \else\if#1E%
%          \ifnum\JSisTEX=1 \chardef\JSisTEX\plustwo   \else\flushJSisTEX\aftergroup E\fi
%        \else\if#1X%
%          \ifnum\JSisTEX=2 \chardef\JSisTEX\plusthree \else\flushJSisTEX\aftergroup X\fi
%        \else\if#1\normalspace
%          \ifnum\JSisTEX=3 \chardef\JSisTEX\zerocount \else\flushJSisTEX\aftergroup#1\fi
%        \else
%          \flushJSisTEX\aftergroup\string\expandafter\aftergroup#1%
%        \fi\fi\fi\fi\fi\fi\fi\fi
%      \fi
%    \fi
%    \dododoPSsanitizeJScode}

% todo: "http:\\" -> simple. maar wel \" afvangen
%
% use new pdftex escape mechanism or make fully expandable version, not used that often btw

\chardef\JSstring\zerocount

\def\doJSlinebreak
 {\chardef\JScomment\zerocount
  \chardef\JSstring\zerocount
  \ifaddJSlinebreaks
    \aftergroup\string\aftergroup\n%
  \fi}

\def\dodoPSsanitizeJScode#1%  % input stack>500 & TEX check
  {\if#1/%
     \ifnum\JSstring=0
       \ifnum\JScomment=0
         \chardef\JScomment\plusone
       \else\ifnum\JScomment=1
         \chardef\JScomment\plustwo
       \fi\fi
     \else
       \aftergroup/%
     \fi
   \else
     \ifnum\JScomment=1
       \aftergroup/%
       \chardef\JScomment\zerocount
     \fi
     % is the delchar trick still needed?
     \ifnum\JScomment=2
       \ifnum`#1=13 % brrr
         \doJSlinebreak
       \else\if#1\par
         \doJSlinebreak
       \else\if#1\delcharacter
         \doJSlinebreak
       \fi\fi\fi
     \else
       \ifnum`#1=13 % brrr
         \flushJSisTEX\doJSlinebreak
       \else\if#1\par
         \flushJSisTEX\doJSlinebreak
       \else\if#1\delcharacter
         \flushJSisTEX\doJSlinebreak
       \else\if#1(%
         \flushJSisTEX\aftergroup\string\expandafter\aftergroup\csname#1\endcsname
       \else\if#1)%
         \flushJSisTEX\aftergroup\string\expandafter\aftergroup\csname#1\endcsname
       %\else\if#1;%
       %  \flushJSisTEX\aftergroup;\doJSlinebreak
       \else\if#1T%
         \ifnum\JSisTEX=0 \chardef\JSisTEX\plusone   \else\flushJSisTEX\aftergroup T\fi
       \else\if#1E%
         \ifnum\JSisTEX=1 \chardef\JSisTEX\plustwo   \else\flushJSisTEX\aftergroup E\fi
       \else\if#1X%
         \ifnum\JSisTEX=2 \chardef\JSisTEX\plusthree \else\flushJSisTEX\aftergroup X\fi
       \else\if#1\normalspace
         \ifnum\JSisTEX=3 \chardef\JSisTEX\zerocount \else\flushJSisTEX\aftergroup#1\fi
       \else
          % todo: "test\"test"
         \if#1"%
           \ifcase\JSstring
             \chardef\JSstring\plusone
           \else
             \chardef\JSstring\zerocount
           \fi
         \fi
         \flushJSisTEX\aftergroup\string\expandafter\aftergroup#1%
       \fi\fi\fi\fi\fi\fi\fi\fi\fi % \fi
     \fi
   \fi
   \dododoPSsanitizeJScode}

%D Close reading learns that one line comments (\type{// ...})
%D are removed from the stream. This permits switching in
%D pretty printing \JAVASCRIPT\ sources as well as saves
%D some bytes.

%D The magic 500 in the next hack prevents the input stack from
%D overflowing when large scripts are sanitized.

%\beginTEX

\def\dododoPSsanitizeJScode
  {\ifcase\JSisTEX\ifcase\JScomment
     \advance\scratchcounter \plusone
   \fi\fi
   \ifnum\scratchcounter=500
     \expandafter\dodododoPSsanitizeJScode
   \fi}

\def\dodododoPSsanitizeJScode
  {\let\next={%
   \aftergroup}%
   \endgroup
   \begingroup
   \aftergroup\xdef
   \aftergroup\sanitizedJScode
   \aftergroup{%
   \aftergroup\sanitizedJScode
   \let\next=}}

%\endTEX
%
% Why is \aftergroup not doing what I expect?
%
% \beginETEX \aftergroup
%
% \let\dododoPSsanitizeJScode\relax
%
% \endETEX

%D The macro \type{\doPSsanitizeJScode} converts its argument
%D into the macro \type{\sanitizedJScode}, thereby prefixing
%D each \type{(} and \type{)} by a slash.

%D Hooking this mechanism into the general \CONTEXT\ reference
%D mechanism does not take much effort:

\definespecialtest{JS}%
  {\doifdefinedelse{\r!java\currentreferenceoperation}}

\definespeciallocation{JS}#1#2%
  {\iflocation
     \bgroup
       \bgroup
         \presetJScode
           \currentreferenceoperation
           \currentreferencearguments
       \egroup
       \dostartgoto
         \data
           {#2}%
         \start
           \dostartgotoJS\buttonwidth\buttonheight\JScode
         \stop
           \dostopgotoJS
       \dostopgoto
     \egroup
   \else
     {#2}%
   \fi}

%D \macros
%D   {useJSscripts}
%D
%D In due time, users will build their collections of scripts,
%D which can be used (loaded) when applicable. Although not all
%D public, we will provide some general purpose scripts,
%D collected in files with names like \type{java-...}. One can
%D load these scripts with \type{\useJSscripts}, like:
%D
%D \starttyping
%D \useJSscripts[fld]
%D \stoptyping
%D
%D The not so complicated implementation of this macro is:

\def\dodouseJSscripts#1%
  {\doifelse{#1}\v!reset
     {\let\allJSpreambles\empty}
     {\doifundefined{\c!file\f!javascriptprefix#1}
        {\startnointerference
           \letgvalueempty{\c!file\f!javascriptprefix#1}%
           \makeshortfilename[\f!javascriptprefix#1]%
           \showmessage\m!javascript1{#1}%
           \startreadingfile
           \readsysfile\shortfilename\donothing\donothing
           \stopreadingfile
         \stopnointerference}}}

\def\douseJSscripts[#1][#2]%
  {\processcommalist[#1]\dodouseJSscripts
   \processcommalist[#2]\useJSpreamblenow}

\def\useJSscripts
  {\dodoubleempty\douseJSscripts}

\protect \endinput
