+% @value{foo} gets the text saved in variable foo.
+{
+ \catcode`\_ = \active
+ %
+ % We might end up with active _ or - characters in the argument if
+ % we're called from @code, as @code{@value{foo-bar_}}. So \let any
+ % such active characters to their normal equivalents.
+ \gdef\value{\begingroup
+ \catcode`\-=\other \catcode`\_=\other
+ \indexbreaks \let_\normalunderscore
+ \valuexxx}
+}
+\def\valuexxx#1{\expandablevalue{#1}\endgroup}
+
+% We have this subroutine so that we can handle at least some @value's
+% properly in indexes (we \let\value to this in \indexdummies). Ones
+% whose names contain - or _ still won't work, but we can't do anything
+% about that. The command has to be fully expandable (if the variable
+% is set), since the result winds up in the index file. This means that
+% if the variable's value contains other Texinfo commands, it's almost
+% certain it will fail (although perhaps we could fix that with
+% sufficient work to do a one-level expansion on the result, instead of
+% complete).
+%
+\def\expandablevalue#1{%
+ \expandafter\ifx\csname SET#1\endcsname\relax
+ {[No value for ``#1'']}%
+ \message{Variable `#1', used in @value, is not set.}%
+ \else
+ \csname SET#1\endcsname
+ \fi
+}
+
+% @ifset VAR ... @end ifset reads the `...' iff VAR has been defined
+% with @set.
+%
+\def\ifset{\parsearg\doifset}
+\def\doifset#1{%
+ \expandafter\ifx\csname SET#1\endcsname\relax
+ \let\next=\ifsetfail
+ \else
+ \let\next=\ifsetsucceed
+ \fi
+ \next
+}
+\def\ifsetsucceed{\conditionalsucceed{ifset}}
+\def\ifsetfail{\doignore{ifset}}
+\defineunmatchedend{ifset}
+
+% @ifclear VAR ... @end ifclear reads the `...' iff VAR has never been
+% defined with @set, or has been undefined with @clear.
+%
+\def\ifclear{\parsearg\doifclear}
+\def\doifclear#1{%
+ \expandafter\ifx\csname SET#1\endcsname\relax
+ \let\next=\ifclearsucceed
+ \else
+ \let\next=\ifclearfail
+ \fi
+ \next
+}
+\def\ifclearsucceed{\conditionalsucceed{ifclear}}
+\def\ifclearfail{\doignore{ifclear}}
+\defineunmatchedend{ifclear}
+
+% @iftex, @ifnothtml, @ifnotinfo, @ifnotplaintext always succeed; we
+% read the text following, through the first @end iftex (etc.). Make
+% `@end iftex' (etc.) valid only after an @iftex.
+%
+\def\iftex{\conditionalsucceed{iftex}}
+\def\ifnothtml{\conditionalsucceed{ifnothtml}}
+\def\ifnotinfo{\conditionalsucceed{ifnotinfo}}
+\def\ifnotplaintext{\conditionalsucceed{ifnotplaintext}}
+\defineunmatchedend{iftex}
+\defineunmatchedend{ifnothtml}
+\defineunmatchedend{ifnotinfo}
+\defineunmatchedend{ifnotplaintext}
+
+% True conditional. Since \set globally defines its variables, we can
+% just start and end a group (to keep the @end definition undefined at
+% the outer level).
+%
+\def\conditionalsucceed#1{\begingroup
+ \expandafter\def\csname E#1\endcsname{\endgroup}%
+}
+
+% @defininfoenclose.
+\let\definfoenclose=\comment
+
+
+\message{indexing,}
+% Index generation facilities
+
+% Define \newwrite to be identical to plain tex's \newwrite
+% except not \outer, so it can be used within \newindex.
+{\catcode`\@=11
+\gdef\newwrite{\alloc@7\write\chardef\sixt@@n}}
+
+% \newindex {foo} defines an index named foo.
+% It automatically defines \fooindex such that
+% \fooindex ...rest of line... puts an entry in the index foo.
+% It also defines \fooindfile to be the number of the output channel for
+% the file that accumulates this index. The file's extension is foo.
+% The name of an index should be no more than 2 characters long
+% for the sake of vms.
+%
+\def\newindex#1{%
+ \iflinks
+ \expandafter\newwrite \csname#1indfile\endcsname
+ \openout \csname#1indfile\endcsname \jobname.#1 % Open the file
+ \fi
+ \expandafter\xdef\csname#1index\endcsname{% % Define @#1index
+ \noexpand\doindex{#1}}
+}
+
+% @defindex foo == \newindex{foo}
+%
+\def\defindex{\parsearg\newindex}
+
+% Define @defcodeindex, like @defindex except put all entries in @code.
+%
+\def\defcodeindex{\parsearg\newcodeindex}
+%
+\def\newcodeindex#1{%
+ \iflinks
+ \expandafter\newwrite \csname#1indfile\endcsname
+ \openout \csname#1indfile\endcsname \jobname.#1
+ \fi
+ \expandafter\xdef\csname#1index\endcsname{%
+ \noexpand\docodeindex{#1}}%
+}
+
+
+% @synindex foo bar makes index foo feed into index bar.
+% Do this instead of @defindex foo if you don't want it as a separate index.
+%
+% @syncodeindex foo bar similar, but put all entries made for index foo
+% inside @code.
+%
+\def\synindex#1 #2 {\dosynindex\doindex{#1}{#2}}
+\def\syncodeindex#1 #2 {\dosynindex\docodeindex{#1}{#2}}
+
+% #1 is \doindex or \docodeindex, #2 the index getting redefined (foo),
+% #3 the target index (bar).
+\def\dosynindex#1#2#3{%
+ % Only do \closeout if we haven't already done it, else we'll end up
+ % closing the target index.
+ \expandafter \ifx\csname donesynindex#2\endcsname \undefined
+ % The \closeout helps reduce unnecessary open files; the limit on the
+ % Acorn RISC OS is a mere 16 files.
+ \expandafter\closeout\csname#2indfile\endcsname
+ \expandafter\let\csname\donesynindex#2\endcsname = 1
+ \fi
+ % redefine \fooindfile:
+ \expandafter\let\expandafter\temp\expandafter=\csname#3indfile\endcsname
+ \expandafter\let\csname#2indfile\endcsname=\temp
+ % redefine \fooindex:
+ \expandafter\xdef\csname#2index\endcsname{\noexpand#1{#3}}%
+}
+
+% Define \doindex, the driver for all \fooindex macros.
+% Argument #1 is generated by the calling \fooindex macro,
+% and it is "foo", the name of the index.
+
+% \doindex just uses \parsearg; it calls \doind for the actual work.
+% This is because \doind is more useful to call from other macros.
+
+% There is also \dosubind {index}{topic}{subtopic}
+% which makes an entry in a two-level index such as the operation index.
+
+\def\doindex#1{\edef\indexname{#1}\parsearg\singleindexer}
+\def\singleindexer #1{\doind{\indexname}{#1}}
+
+% like the previous two, but they put @code around the argument.
+\def\docodeindex#1{\edef\indexname{#1}\parsearg\singlecodeindexer}
+\def\singlecodeindexer #1{\doind{\indexname}{\code{#1}}}
+
+% Take care of Texinfo commands that can appear in an index entry.
+% Since there are some commands we want to expand, and others we don't,
+% we have to laboriously prevent expansion for those that we don't.
+%
+\def\indexdummies{%
+ \def\@{@}% change to @@ when we switch to @ as escape char in index files.
+ \def\ {\realbackslash\space }%
+ % Need these in case \tex is in effect and \{ is a \delimiter again.
+ % But can't use \lbracecmd and \rbracecmd because texindex assumes
+ % braces and backslashes are used only as delimiters.
+ \let\{ = \mylbrace
+ \let\} = \myrbrace
+ %
+ % \definedummyword defines \#1 as \realbackslash #1\space, thus
+ % effectively preventing its expansion. This is used only for control
+ % words, not control letters, because the \space would be incorrect
+ % for control characters, but is needed to separate the control word
+ % from whatever follows.
+ %
+ % For control letters, we have \definedummyletter, which omits the
+ % space.
+ %
+ % These can be used both for control words that take an argument and
+ % those that do not. If it is followed by {arg} in the input, then
+ % that will dutifully get written to the index (or wherever).
+ %
+ \def\definedummyword##1{%
+ \expandafter\def\csname ##1\endcsname{\realbackslash ##1\space}%
+ }%
+ \def\definedummyletter##1{%
+ \expandafter\def\csname ##1\endcsname{\realbackslash ##1}%
+ }%
+ %
+ % Do the redefinitions.
+ \commondummies
+}
+
+% For the aux file, @ is the escape character. So we want to redefine
+% everything using @ instead of \realbackslash. When everything uses
+% @, this will be simpler.
+%
+\def\atdummies{%
+ \def\@{@@}%
+ \def\ {@ }%
+ \let\{ = \lbraceatcmd
+ \let\} = \rbraceatcmd
+ %
+ % (See comments in \indexdummies.)
+ \def\definedummyword##1{%
+ \expandafter\def\csname ##1\endcsname{@##1\space}%
+ }%
+ \def\definedummyletter##1{%
+ \expandafter\def\csname ##1\endcsname{@##1}%
+ }%
+ %
+ % Do the redefinitions.
+ \commondummies
+}
+
+% Called from \indexdummies and \atdummies. \definedummyword and
+% \definedummyletter must be defined first.
+%
+\def\commondummies{%
+ %
+ \normalturnoffactive
+ %
+ % Control letters and accents.
+ \definedummyletter{_}%
+ \definedummyletter{,}%
+ \definedummyletter{"}%
+ \definedummyletter{`}%
+ \definedummyletter{'}%
+ \definedummyletter{^}%
+ \definedummyletter{~}%
+ \definedummyletter{=}%
+ \definedummyword{u}%
+ \definedummyword{v}%
+ \definedummyword{H}%
+ \definedummyword{dotaccent}%
+ \definedummyword{ringaccent}%
+ \definedummyword{tieaccent}%
+ \definedummyword{ubaraccent}%
+ \definedummyword{udotaccent}%
+ \definedummyword{dotless}%
+ %
+ % Other non-English letters.
+ \definedummyword{AA}%
+ \definedummyword{AE}%
+ \definedummyword{L}%
+ \definedummyword{OE}%
+ \definedummyword{O}%
+ \definedummyword{aa}%
+ \definedummyword{ae}%
+ \definedummyword{l}%
+ \definedummyword{oe}%
+ \definedummyword{o}%
+ \definedummyword{ss}%
+ %
+ % Although these internal commands shouldn't show up, sometimes they do.
+ \definedummyword{bf}%
+ \definedummyword{gtr}%
+ \definedummyword{hat}%
+ \definedummyword{less}%
+ \definedummyword{sf}%
+ \definedummyword{sl}%
+ \definedummyword{tclose}%
+ \definedummyword{tt}%
+ %
+ % Texinfo font commands.
+ \definedummyword{b}%
+ \definedummyword{i}%
+ \definedummyword{r}%
+ \definedummyword{sc}%
+ \definedummyword{t}%
+ %
+ \definedummyword{TeX}%
+ \definedummyword{acronym}%
+ \definedummyword{cite}%
+ \definedummyword{code}%
+ \definedummyword{command}%
+ \definedummyword{dfn}%
+ \definedummyword{dots}%
+ \definedummyword{emph}%
+ \definedummyword{env}%
+ \definedummyword{file}%
+ \definedummyword{kbd}%
+ \definedummyword{key}%
+ \definedummyword{math}%
+ \definedummyword{option}%
+ \definedummyword{samp}%
+ \definedummyword{strong}%
+ \definedummyword{uref}%
+ \definedummyword{url}%
+ \definedummyword{var}%
+ \definedummyword{verb}%
+ \definedummyword{w}%
+ %
+ % Assorted special characters.
+ \definedummyword{bullet}%
+ \definedummyword{copyright}%
+ \definedummyword{dots}%
+ \definedummyword{enddots}%
+ \definedummyword{equiv}%
+ \definedummyword{error}%
+ \definedummyword{expansion}%
+ \definedummyword{minus}%
+ \definedummyword{pounds}%
+ \definedummyword{point}%
+ \definedummyword{print}%
+ \definedummyword{result}%
+ %
+ % Handle some cases of @value -- where the variable name does not
+ % contain - or _, and the value does not contain any
+ % (non-fully-expandable) commands.
+ \let\value = \expandablevalue
+ %
+ % Normal spaces, not active ones.
+ \unsepspaces
+ %
+ % No macro expansion.
+ \turnoffmacros
+}
+
+% If an index command is used in an @example environment, any spaces
+% therein should become regular spaces in the raw index file, not the
+% expansion of \tie (\leavevmode \penalty \@M \ ).
+{\obeyspaces
+ \gdef\unsepspaces{\obeyspaces\let =\space}}
+
+
+% \indexnofonts is used when outputting the strings to sort the index
+% by, and when constructing control sequence names. It eliminates all
+% control sequences and just writes whatever the best ASCII sort string
+% would be for a given command (usually its argument).
+%
+\def\indexdummytex{TeX}
+\def\indexdummydots{...}
+%
+\def\indexnofonts{%
+ \def\ { }%
+ \def\@{@}%
+ % how to handle braces?
+ \def\_{\normalunderscore}%
+ %
+ \let\,=\asis
+ \let\"=\asis
+ \let\`=\asis
+ \let\'=\asis
+ \let\^=\asis
+ \let\~=\asis
+ \let\==\asis
+ \let\u=\asis
+ \let\v=\asis
+ \let\H=\asis
+ \let\dotaccent=\asis
+ \let\ringaccent=\asis
+ \let\tieaccent=\asis
+ \let\ubaraccent=\asis
+ \let\udotaccent=\asis
+ \let\dotless=\asis
+ %
+ % Other non-English letters.
+ \def\AA{AA}%
+ \def\AE{AE}%
+ \def\L{L}%
+ \def\OE{OE}%
+ \def\O{O}%
+ \def\aa{aa}%
+ \def\ae{ae}%
+ \def\l{l}%
+ \def\oe{oe}%
+ \def\o{o}%
+ \def\ss{ss}%
+ \def\exclamdown{!}%
+ \def\questiondown{?}%
+ %
+ % Don't no-op \tt, since it isn't a user-level command
+ % and is used in the definitions of the active chars like <, >, |, etc.
+ % Likewise with the other plain tex font commands.
+ %\let\tt=\asis
+ %
+ % Texinfo font commands.
+ \let\b=\asis
+ \let\i=\asis
+ \let\r=\asis
+ \let\sc=\asis
+ \let\t=\asis
+ %
+ \let\TeX=\indexdummytex
+ \let\acronym=\asis
+ \let\cite=\asis
+ \let\code=\asis
+ \let\command=\asis
+ \let\dfn=\asis
+ \let\dots=\indexdummydots
+ \let\emph=\asis
+ \let\env=\asis
+ \let\file=\asis
+ \let\kbd=\asis
+ \let\key=\asis
+ \let\math=\asis
+ \let\option=\asis
+ \let\samp=\asis
+ \let\strong=\asis
+ \let\uref=\asis
+ \let\url=\asis
+ \let\var=\asis
+ \let\verb=\asis
+ \let\w=\asis
+}