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%D \module
%D [ file=syst-etx,
%D version=1999.03.17, % some time ...
%D title=\CONTEXT\ System Macros,
%D subtitle=Efficient \PLAIN\ \TEX\ loading,
%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.
%D This module prepares \CONTEXT\ for \ETEX. We don't use
%D the definition files that come with this useful \TEX\
%D extension, but implement our own alternatives.
%D \CONTEXT\ was one of the first systems that had support for \ETEX\
%D built in. In the process we found out that the extensions were not
%D as bug free as the rest of \TEX. Especially the bugs in \type
%D {lastnode}, flushing of token lists with an index in the extension
%D range, and spurious box behaviour of boxes adressed in the extended
%D box space made us a bit careful. It's hard to to track down such
%D bugs, especially if one has a mind set of \TEX\ being bug free. If
%D you encounter unexpected behaviour let me know. Currently the
%D scantokens mechanism can handle only one||liners, but Taco will
%D provide an alternative some day.
%D
%D \starttyping
%D \bgroup
%D \lccode`a=12\lowercase{\xdef\whatever{a}}\egroup
%D \def\whatever{test \whatever test}
%D \scantokens\expandafter{\whatever}
%D \egroup
%D \stoptyping
\unprotect
%D \ETEX\ has a not so handy way of telling you the version number,
%D i.e. the revision number has a period in it:
\long\def\gobbleoneargument#1{}
\beginETEX
\mathchardef\etexversion=\numexpr\eTeXversion*100+\expandafter\gobbleoneargument\eTeXrevision\relax
\endETEX
\beginTEX
\mathchardef\etexversion=0
\endTEX
%D Constants to be used with \type {\grouptype}.
\chardef\@@bottomlevelgroup = 0
\chardef\@@simplegroup = 1
\chardef\@@hboxgroup = 2
\chardef\@@adjustedhboxgroup = 3
\chardef\@@vboxgroup = 4
\chardef\@@vtopgroup = 5
\chardef\@@aligngroup = 6
\chardef\@@noaligngroup = 7
\chardef\@@outputgroup = 8
\chardef\@@mathgroup = 9
\chardef\@@discretionarygroup = 10
\chardef\@@insertgroup = 11
\chardef\@@vcentergroup = 12
\chardef\@@mathchoicegroup = 13
\chardef\@@semisimplegroup = 14
\chardef\@@mathshiftgroup = 15
\chardef\@@mathleftgroup = 16
\chardef\@@vadjustgroup = \@@insertgroup
%D Constants to be used with \type {\interactionmode}.
\chardef\@@batchmode = 0
\chardef\@@nonstopmode = 1
\chardef\@@scrollmode = 2
\chardef\@@errorstopmode = 3
%D Constants to be used with \type {\lastnodetype}.
\chardef\@@charnode = 0
\chardef\@@hlistnode = 1
\chardef\@@vlistnode = 2
\chardef\@@rulenode = 3
\chardef\@@insertnode = 4
\chardef\@@marknode = 5
\chardef\@@adjustnode = 6
\chardef\@@ligaturenode = 7
\chardef\@@discretionarynode = 8
\chardef\@@whatsitnode = 9
\chardef\@@mathnode = 10
\chardef\@@gluenode = 11
\chardef\@@kernnode = 12
\chardef\@@penaltynode = 13
\chardef\@@unsetnode = 14
\chardef\@@mathsnode = 15
%D Constants to be used with \type {\iftype}.
\chardef\@@charif = 1
\chardef\@@catif = 2
\chardef\@@numif = 3
\chardef\@@dimif = 4
\chardef\@@oddif = 5
\chardef\@@vmodeif = 6
\chardef\@@hmodeif = 7
\chardef\@@mmodeif = 8
\chardef\@@innerif = 9
\chardef\@@voidif = 10
\chardef\@@hboxif = 11
\chardef\@@vboxif = 12
\chardef\@@xif = 13
\chardef\@@eofif = 14
\chardef\@@trueif = 15
\chardef\@@falseif = 16
\chardef\@@caseif = 17
\chardef\@@definedif = 18
\chardef\@@csnameif = 19
\chardef\@@fontcharif = 20
%D Just in case we are not using \ETEX, we define some out of
%D range constants.
\beginTEX
\chardef\grouptype = 255
\chardef\interactionmode = 255
\chardef\nodetype = 255
\chardef\iftype = 255
\endTEX
%D Of course we want even bigger log files, so we copied this
%D from the \ETEX\ source files.
\beginETEX \tracing...
\def\tracingall
{\tracingonline \@ne
\tracingcommands \thr@@
\tracingstats \tw@
\tracingpages \@ne
\tracingoutput \@ne
\tracinglostchars \tw@
\tracingmacros \tw@
\tracingparagraphs\@ne
\tracingrestores \@ne
\showboxbreadth \maxdimen
\showboxdepth \maxdimen
\tracinggroups \@ne
\tracingifs \@ne
\tracingscantokens\@ne
\tracingnesting \@ne
\tracingassigns \tw@
\errorstopmode}
\def\loggingall
{\tracingall
\tracingonline \z@}
\def\tracingnone
{\tracingassigns \z@
\tracingnesting \z@
\tracingscantokens\z@
\tracingifs \z@
\tracinggroups \z@
\showboxdepth \thr@@
\showboxbreadth 5
\tracingrestores \z@
\tracingparagraphs\z@
\tracingmacros \z@
\tracinglostchars \@ne
\tracingoutput \z@
\tracingpages \z@
\tracingstats \z@
\tracingcommands \z@
\tracingonline \z@ }
\endETEX
%D Just to be sure:
\ifx\eTeX\undefined
\def\eTeX{$\varepsilon$-\TeX}
\fi
%D In \ETEX\ we have lots of registers, so we redefine a few
%D low level macros. We reserve some extra space for inserts
%D and as soon as we near the end of the first register
%D memory bank (often some 10 less than 255), we switch to the
%D slower range \type {\@@medallocation}||\type {\@@maxallocation}.
\beginETEX \new...
%D First we redefine the plain \TEX\ register allocation macros.
\def\newcount {\myalloc@0\count \countdef \@@maxallocation}
\def\newdimen {\myalloc@1\dimen \dimendef \@@maxallocation}
\def\newskip {\myalloc@2\skip \skipdef \@@maxallocation}
\def\newmuskip {\myalloc@3\muskip \muskipdef \@@maxallocation}
\def\newbox {\myalloc@4\box \mathchardef\@@maxallocation}
\def\newtoks {\myalloc@5\toks \toksdef \@@maxallocation}
\def\newread {\myalloc@6\read \chardef \@@minallocation}
\def\newwrite {\myalloc@7\write \chardef \@@minallocation}
\def\newmarks {\myalloc@8\marks \mathchardef\@@maxallocation}
\def\newlanguage{\myalloc@9\language\chardef \@@minallocation}
%D Since in \CONTEXT\ we only have one math family left we
%D redefine \type {\newfam}.
\def\newfam#1{\chardef#1=15 }
%D Therefore we should reset the related counter.
\count18=1
%D We use some constants in the tests.
\mathchardef\@@minallocation = 16
\mathchardef\@@medallocation = 256
\mathchardef\@@maxallocation = 32767
%D I cannot imagine that more than~8 extra insert classes
%D are needed, but, for critical editions, we may need many
%D more, so:
\chardef\@@insallocation=32
%D However, there's a bug in \ETEX\ versions smaller than 2.2,
%D so we need to play safe:
\ifnum\etexversion<202 \chardef\@@insallocation=8 \fi
%D My low level allocation macro now comes down to:
\def\myalloc@#1#2#3#4#5%
{\global\advance\count1#1by\@ne
\ifnum\count1#1>\@@medallocation \else
\global\advance\insc@unt by -\@@insallocation
\ifnum\count1#1<\insc@unt \else
\global\count1#1=\@@medallocation % \wait
\fi
\global\advance\insc@unt by +\@@insallocation
\fi
\ifnum\count1#1>#4%
\global\count1#1=#4%
\errmessage{No room for (\string#2) \string#5}%
\fi
\allocationnumber=\count1#1%
\global#3#5=\allocationnumber
\wlog{\string#5=\string#2\the\allocationnumber}}
\endETEX
%D These macros can be checked by tests like:
%D
%D \starttyping
%D \let\wlog\message \dorecurse{1000}{\newcount\dummy}
%D \stoptyping
%D A few bonus bindings.
\let\normalprotected = \protected
\let\normalunexpanded = \unexpanded
%D \macros
%D {begcsname}
%D
%D Handy for \ETEX-only usage:
\beginETEX \ifcsname
\def\begcsname#1\endcsname{\ifcsname#1\endcsname\csname#1\endcsname\fi}
\endETEX
\beginTEX
\def\begcsname#1\endcsname{\csname#1\endcsname}
\endTEX
\protect \endinput
|
