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|
\catcode `\@ = 11 %%% we use commercial-at as a letter throughout;
\chardef \l@tter = 11 %%% and introduce synonyms for the \catcodes for
\chardef \@ther = 12 %%% <letter> and <other>;
\newcount \c@unt %%% a loop-counter;
\newcount \ch@rcode %%% this will hold the character-code of the
%%% escape character;
\newif \ifd@bugging %%% set <true> if you want to watch the
%%% finite-state automaton at work;
\newif \ifshewleadingspaces %%% set <true> if you want to see leading spaces
%%% shewn as inverted square cup (explicit);
\newif \ifshewembeddedspaces %%% set <false> if you want to see embedded
\shewembeddedspacestrue %%% spaces shewn as white space (implicit);
\ifd@bugging %%% if <debugging>,
\let \m@ssage = \message %%% \m@ssage is synonymous with \message
\else %%% otherwise
\def \m@ssage #1{}% %%% it simply throws its parameter away;
\fi
%
\def \verbatim %%% the \verbatim macro takes no parameter
{\begingroup %%% and immediately starts a nested group
\tracingonline = 0
\def \n@sted %%% within which \n@sted is defined
{\begingroup %%% to start a further group within which
\let \n@sted %%% \n@sted becomes a synonym for \endgroup
= \endgroup
\@nvironment %%% and the environment is restored to that
%%% which obtained two levels of nesting out;
\ignorespaces %%% for tidyness, we ignore any <lwsp>
}% %%% which follows the escape character;
\edef \@nvironment %%% we initialise \@nvironment
{\the \font %%% who forgot this ?????
\parindent = %%% to prepare to restore \parindent
\the \parindent
\parskip = %%% and \parskip;
\the \parskip
\space %%% and ensure that the value to be assigned to
}% %%% \parskip is properly terminated;
\displayverbatimfont %%% we assume Knuth's font-selectors and
%%% select the `typewriter' font;
\parskip = 0 pt %%% we then set \parindent and
\parindent = 0 pt %%% \parskip to 0 pt;
\c@unt = 0 %%% and initialise \count to 0;
\loop %%% this loop checks the \catcode of each
%%% character code in the range 0 .. 127
%%% (or 0 .. 255 for TeX V3) and if it
%%% is other than <letter> or <other>, as
%%% appropriate, saves the current value in
%%% \@nvironment for subsequent restoration
%%% within an inner group; it then sets the
%%% \catcode to either <letter> or <other>;
\ifnum \c@unt < `\A
\s@ve \catcode \c@unt = \@ther
\else \ifnum \c@unt > `\z
\s@ve \catcode \c@unt = \@ther
\else \ifnum \c@unt > `\Z
\ifnum \c@unt < `\a
\s@ve \catcode \c@unt = \@ther
\else \s@ve \catcode \c@unt = \l@tter
\fi
\else \s@ve \catcode \c@unt = \l@tter
\fi
\fi
\fi
\advance \c@unt by 1
\ifnum \c@unt < 256 % or 128 for the V2 sites ...
\repeat
\v@rbatim
}
%
\def \v@rbatim #1% %%%
{\if #1 %%%
\let \n@xt = \v@rb@tim %%%
\else %%%
\def \n@xt %%%
{\v@rb@tim #1}% %%%
\fi %%%
\n@xt %%%
} %%%
%
\def \v@rb@tim #1%
{\ch@rcode = `#1 %%%
\edef \@nvironment %%% and append code to \@nvironment
{\@nvironment %%% to make the escape character active;
\catcode \the \ch@rcode
= \active
\space %%% <space> separates list items in \@nvironment
}%
\catcode \ch@rcode %%% the escape character is made active;
= \active
\uccode `\^^M = \ch@rcode %%% and the upper-case code of <return> is made
%%% equal to the character-code of the escape
%%% character; this is necessary because only
%%% <return> can be guaranteed to be active at
%%% this point, and we need an active character
%%% to form the primary operand of \def;
%%% the \@x's below are \expandafter's,
%%% and the effect is to upper-case <return>
%%% (yielding the escape character), then \def
%%% (an active instance of) this character as
%%% \n@sted, which has been defined above;
%
\@x \uppercase \@x {\@x \def \r@turn {\n@sted}}%
%
\uccode `\^^M = 0 %%% the upper-case code of <return> is then re-
%%% instated (not strictly true; it is set to 0,
%%% which is assumed to be its previous value
%%% --- could be improved here);
\@ctivecr %%% <return> is made active;
\@ctivespace %%% and so is <space> (to avoid space-elision);
%%% finally, the finite-state automaton which
}% %%% processes <space>s is set to <????>;
%%% this ends the definition of \verbatim.
%
\def \s@ve #1#2=#3% %%% \s@ve minimises the \catcode restoration
{\ifnum #1#2 = #3% %%% work of \@nvironment by saving only the
%%% \catcode of characters whose \catcode
%%% is to be changed; it then changes the
%%% \catcode of those characters.
\else \edef \@nvironment
{\@nvironment #1\the #2=\the #1#2 }%
#1#2 = #3%
\fi
}%
%%% the code which follows implements the finite
%%% state automaton which determines whether
%%% <space>s are ignored, shewn explicitly or
%%% implied, and which ensures that blank
%%% lines are reproduced correctly.
%
\def \v@id {\futurelet \n@xt \v@idifspace}%
\def \l@ad {\l@adingspace \futurelet \n@xt \l@adifspace}%
\def \sk@p {\vskip \baselineskip \futurelet \n@xt \l@adifspace}%
\def \emb@d {\emb@ddedspace}%
\def \sh@wspace {\char 32\relax}%
\def \h@despace {\leavevmode \kern \fontdimen 2 \font}%
\def \l@adingspace {\ifshewleadingspaces \sh@wspace \else \h@despace \fi}%
\def \emb@ddedspace {\ifshewembeddedspaces \sh@wspace \else \h@despace \fi}%
\def \v@idifspace {\testn@xt {\afterassignment \v@id}}%
\def \l@adifspace {\testn@xt {\afterassignment \sk@p}}%
%
%%% \testn@xt provides a common look-ahead for
%%% \v@idifspace and \l@adifspace, and also
\def \testn@xt #1% %%% implements some essential debugging hooks.
{\ifx \n@xt \sp@c@
\m@ssage {Next character is a space}%
\let \n@xt = \relax
\else \ifx \n@xt \r@t@rn
\m@ssage {Next character is a return}%
\def \n@xt {#1\let \n@xt = }%
\else \m@ssage {Next character is \meaning \n@xt}%
\let \n@xt = \relax
\@x \let \sp@ce = \emb@d
\fi
\fi
\n@xt
}%
%
%%% We next tamper with the \catcode of <space>
%%% and <return>, while defining macros and
%%% synonyms which require them to be active;
%%% the \catcode is then restored to its default
%%% (not necessarily the previous value ---
%%% could be improved). \@ctivespace makes
%%% <space> active, then defines <space> as
\catcode `\ = \active% %%% \v@id with a synonym \sp@c@. This code is
\def\sp@ce{ }% %%% used by the finite-state automaton.
\def\@ctivespace%
{\catcode`\ =\active\def {\v@id}\let\sp@c@= }\catcode`\ =10\relax%
\catcode`\ =10\relax%
%
\catcode `\^^M = \active % %%% <return> is made active;
\def \r@turn {^^M}% %%% \r@turn defined as an active <return>;
\let \r@t@rn = ^^M% %%% \r@t@rn is made a synonym;
\def \@ctivecr % %%% and \@ctivecr is defined to
{\catcode `\^^M = \active % %%% make <return> active, then
\def ^^M% %%% define <return> to manipulate the
%%% finite-state automaton and ...
{\@x \def \sp@ce {\l@ad}%
\@x \let \@x \sp@c@ \@x =\sp@ce %
%
\endgraf % %%% insert a \par primitive (for blank lines).
%
\futurelet \n@xt \l@adifspace %
}%
\let \r@t@rn = ^^M% %%% \r@t@rn is synonymous with active <return>
}%
\catcode `\^^M = 5 % %%% finally, the \catcode of <return> is
%%% restored to its normal value;
%
%%% the \AfterGroup macro is intended for
%%% use within a nested normal environment,
%%% and causes (a concealed macro defined as)
%%% its parameter text to be inserted into
%%% TeX's input stream when the nested normal
%%% group terminates.
%
\def \AfterGroup #1{\global \def \@ftergroup {#1}\aftergroup \@ftergroup}%
%
\let \@x = \expandafter %%% \@x is a brief synonym for \expandafter;
%
%
\def \mitabrev %%% and \mitabrev defined as the closure for
{\endgroup \endgroup}% %%% \verbatim; any other name could be used,
%%% as the code performs no look-ahead for
%%% any particular string.
%
%%% Finally we announce to the world that we
%%% have been loaded, and gives some clues as
%%% to the usage.
%
\catcode `\Ý = \active
\catcode `\| = \active
\def Ý{\begingroup
\def \s@lidus ##1Ý{\inlineverbatimfont ##1\endgroup}%
\p@ssivate \activesp@ces \s@lidus
}
\def |{\begingroup
\def \s@lidus ##1|{\inlineverbatimfont ##1\endgroup}%
\p@ssivate \activesp@ces \s@lidus
}
\def \p@ssivate
{\tracingonline = 0
\c@unt = 0
\loop
\ifnum \catcode \c@unt = 11 {}%
\else \ifnum \catcode \c@unt = 12 {}%
\else \catcode \c@unt = 12
\fi
\fi
\ifnum
\c@unt < 255
\advance \c@unt by 1
\repeat
\catcode `\Ý = \active
\catcode `\| = \active
}
\begingroup
\catcode `\ = \active\gdef\activesp@ce{\def {\phantom{\char`\ }}}%
\endgroup
\def \activesp@ces {\catcode `\ = \active \activesp@ce}
\catcode `\@ = \@ther %%% commercial-at is restored to its normal
%%% <other> catcode (not necessarily the
%%% previous value --- could be improved);
\message {Verbatim environment loaded;}%
\message {usage: ``\noexpand \verbatim <char> ... <char> \noexpand \mitabrev''}%
\message {less functional short forms: \string Ý...\string Ý &
\string |...\string |}%
%%% ======================================================================== %%%
|
