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%D \module
%D [ file=catc-sym,
%D version=1997.01.03, % moved code
%D title=\CONTEXT\ Catcode Macros,
%D subtitle=Some Handy Constants,
%D author=Hans Hagen,
%D date=\currentdate,
%D copyright=\PRAGMA]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.
% we now have loaded syst-* so we have all @@catcode constants
%D We want to have access to the raw alternatives of the
%D special characters. We use a \type {\xdef} instead of
%D \type {\let} because we need an expandable token in a
%D \type {\write}.
\bgroup
\catcode`B=\begingroupcatcode
\catcode`E=\endgroupcatcode
\catcode`.=\escapecatcode
.catcode `.{ 12 .xdef .letteropenbrace B.string{E
.catcode `.} 12 .xdef .letterclosebrace B.string}E
.catcode `.& 12 .xdef .letterampersand B.string&E
.catcode `.< 12 .xdef .letterless B.string<E
.catcode `.> 12 .xdef .lettermore B.string>E
.catcode `.# 12 .xdef .letterhash B.string#E
.catcode `." 12 .xdef .letterdoublequote B.string"E
.catcode `.' 12 .xdef .lettersinglequote B.string'E
.catcode `.$ 12 .xdef .letterdollar B.string$E
.catcode `.% 12 .xdef .letterpercent B.string%E
.catcode `.^ 12 .xdef .letterhat B.string^E
.catcode `._ 12 .xdef .letterunderscore B.string_E
.catcode `.| 12 .xdef .letterbar B.string|E
.catcode `.~ 12 .xdef .lettertilde B.string~E
.catcode `.\ 12 .xdef .letterbackslash B.string\E
.catcode `./ 12 .xdef .letterslash B.string/E
.catcode `.? 12 .xdef .letterquestionmark B.string?E
.catcode `.! 12 .xdef .letterexclamationmark B.string!E
.catcode `.@ 12 .xdef .letterat B.string@E
.catcode `.: 12 .xdef .lettercolon B.string:E
.global .let .letterescape .letterbackslash
.global .let .letterbgroup .letteropenbrace
.global .let .letteregroup .letterclosebrace
.global .let .letterleftbrace .letteropenbrace
.global .let .letterrightbrace .letterclosebrace
.egroup
%D \macros
%D {uncatcodespecials,setnaturalcatcodes,setnormalcatcodes,
%D uncatcodecharacters,uncatcodeallcharacters,
%D uncatcodespacetokens}
%D
%D The following macros are more or less replaced by switching
%D to a catcode table (which we simulate in \MKII) but we keep
%D them for convenience and compatibility. Some old engine code
%D has been removed.
\def\uncatcodespecials {\setcatcodetable\nilcatcodes \uncatcodespacetokens}
\def\setnaturalcatcodes {\setcatcodetable\nilcatcodes}
\def\setnormalcatcodes {\setcatcodetable\ctxcatcodes} % maybe \texcatcodes
\def\uncatcodecharacters {\setcatcodetable\nilcatcodes} % was fast version, gone now
\def\uncatcodeallcharacters{\setcatcodetable\nilcatcodes} % was slow one, with restore
\def\uncatcodespacetokens
{\catcode\spaceasciicode \spacecatcode
\catcode\formfeedasciicode \ignorecatcode
\catcode\endoflineasciicode\endoflinecatcode
\catcode\delasciicode \ignorecatcode}
%D \macros
%D {setverbosecharacter,setverbosecscharacters}
%D
%D Next follows a definition that lets some shortcuts expand to
%D themselves. This macro is meant for \POSTSCRIPT\ and \PDF\
%D code passed on to the backend.
\newtoks\everyverbosechacters
\def\setverbosecscharacter#1%
{\edef#1{\string#1}}
\def\setverbosecscharacters
{\the\everyverbosechacters}
\bgroup
% if used often we can move the code inline
\catcode\barasciicode \activecatcode
\catcode\tildeasciicode\activecatcode
\global \everyverbosechacters =
{\setverbosecscharacter |\setverbosecscharacter ~% context specific
\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\/}
\egroup
%D (Inspired by a discussion on the \CONTEXT\ mailing list)
%D
%D In \TEX\ each character can have one of 16 catcodes. This way the
%D backslash, dollar, ampersand, hash and some more characters get
%D their special meaning. If you want to process tokens under a
%D certain catcode regime, passing arguments can interfere badly.
%D
%D \startbuffer[a]
%D \def\whatever#1{[#1]}
%D \whatever{whatever \type {\whatever{you want}} $or$ not!}
%D \stopbuffer
%D
%D \typebuffer[a]
%D
%D Here we pass an argument to \type {\whatever} but part of that
%D argument is to be processed under a different catcode regime, i.e.\
%D all characters that need to be typeset verbatim need to get
%D the catcode that makes it a letter. This is what we get when we typeset
%D the text verbatim:
%D
%D \starttyping
%D whatever \type {\whatever{you want}} $or$ not!
%D \stoptyping
%D
%D However, when passed to \type {\whatever} we get:
%D
%D \getbuffer[a]
%D
%D In \ETEX\ one can use \type {\scantokens} to circumvent this problem.
%D
%D \startbuffer[b]
%D \def\rescan#1{\scantokens{#1}}
%D \def\whatever#1{[\rescan{#1}]}
%D \whatever{whatever \type {\whatever{you want}} $or$ not!}
%D \stopbuffer
%D
%D \getbuffer[b] \typebuffer[b]
%D
%D This time the \type {\whatever} call gives:
%D
%D \getbuffer[b]
%D
%D In this example, two spaces have crept in. The first one, after the
%D macro name, is inserted by \TEX\ and cannot be avoided. The last space
%D is inserted by \type {\scantokens}, and is the consequence of the fact
%D that this macro mimics reading from a file. You can avoid the last
%D space by a slightly different definition:
%D
%D \startbuffer[c]
%D \def\rescan#1{\scantokens{#1\ignorespaces}}
%D \def\whatever#1{[\rescan{#1}]}
%D \whatever{whatever \type {\whatever{you want}} $or$ not!}
%D \stopbuffer
%D
%D \typebuffer[c]
%D
%D Unfortunately we still keep the first space, but at least it's better than
%D a failure:
%D
%D \getbuffer[c]
\long\def\rescan#1{\scantokens{#1\ignorespaces}}
\long\def\rescanwithsetup#1#2{\begingroup\directsetup{#1}\scantokens{#2\ignorespaces}\endgroup}
\ifx\scantextokens\undefined \else
\long\def\rescan#1{\scantextokens{#1}}
\long\def\rescanwithsetup#1#2{\begingroup\directsetup{#1}\scantextokens{#2}\endgroup}
\fi
\endinput
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