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\def\argremovec#1\c#2\relax{\toks0 = {#1}}
\def\argremovecomment#1\comment#2\relax{\toks0 = {#1}}
% \argremovec{,omment} might leave us with trailing spaces, though; e.g.,
% @end itemize @c foo
% will have two active spaces as part of the argument with the
% `itemize'. Here we remove all active spaces from #1, and assign the
% result to \toks0.
%
% This loses if there are any *other* active characters besides spaces
% in the argument -- _ ^ +, for example -- since they get expanded.
% Fortunately, Texinfo does not define any such commands. (If it ever
% does, the catcode of the characters in questionwill have to be changed
% here.) But this means we cannot call \removeactivespaces as part of
% \argremovec{,omment}, since @c uses \parsearg, and thus the argument
% that \parsearg gets might well have any character at all in it.
%
\def\removeactivespaces#1{%
\begingroup
\ignoreactivespaces
\edef\temp{#1}%
\global\toks0 = \expandafter{\temp}%
\endgroup
}
% Change the active space to expand to nothing.
%
\begingroup
\obeyspaces
\gdef\ignoreactivespaces{\obeyspaces\let =\empty}
\endgroup
\def\flushcr{\ifx\par\lisppar \def\next##1{}\else \let\next=\relax \fi \next}
%% These are used to keep @begin/@end levels from running away
%% Call \inENV within environments (after a \begingroup)
\newif\ifENV \ENVfalse \def\inENV{\ifENV\relax\else\ENVtrue\fi}
\def\ENVcheck{%
\ifENV\errmessage{Still within an environment; press RETURN to continue}
\endgroup\fi} % This is not perfect, but it should reduce lossage
% @begin foo is the same as @foo, for now.
\newhelp\EMsimple{Press RETURN to continue.}
\outer\def\begin{\parsearg\beginxxx}
\def\beginxxx #1{%
\expandafter\ifx\csname #1\endcsname\relax
{\errhelp=\EMsimple \errmessage{Undefined command @begin #1}}\else
\csname #1\endcsname\fi}
% @end foo executes the definition of \Efoo.
%
\def\end{\parsearg\endxxx}
\def\endxxx #1{%
\removeactivespaces{#1}%
\edef\endthing{\the\toks0}%
%
\expandafter\ifx\csname E\endthing\endcsname\relax
\expandafter\ifx\csname \endthing\endcsname\relax
% There's no \foo, i.e., no ``environment'' foo.
\errhelp = \EMsimple
\errmessage{Undefined command `@end \endthing'}%
\else
\unmatchedenderror\endthing
\fi
\else
% Everything's ok; the right environment has been started.
\csname E\endthing\endcsname
\fi
}
% There is an environment #1, but it hasn't been started. Give an error.
%
\def\unmatchedenderror#1{%
\errhelp = \EMsimple
\errmessage{This `@end #1' doesn't have a matching `@#1'}%
}
% Define the control sequence \E#1 to give an unmatched @end error.
%
\def\defineunmatchedend#1{%
\expandafter\def\csname E#1\endcsname{\unmatchedenderror{#1}}%
}
%% Simple single-character @ commands
% @@ prints an @
% Kludge this until the fonts are right (grr).
\def\@{{\tt\char64}}
% This is turned off because it was never documented
% and you can use @w{...} around a quote to suppress ligatures.
%% Define @` and @' to be the same as ` and '
%% but suppressing ligatures.
%\def\`{{`}}
%\def\'{{'}}
% Used to generate quoted braces.
\def\mylbrace {{\tt\char123}}
\def\myrbrace {{\tt\char125}}
\let\{=\mylbrace
\let\}=\myrbrace
\begingroup
% Definitions to produce \{ and \} commands for indices,
% and @{ and @} for the aux file.
\catcode`\{ = \other \catcode`\} = \other
\catcode`\[ = 1 \catcode`\] = 2
\catcode`\! = 0 \catcode`\\ = \other
!gdef!lbracecmd[\{]%
!gdef!rbracecmd[\}]%
!gdef!lbraceatcmd[@{]%
!gdef!rbraceatcmd[@}]%
!endgroup
% Accents: @, @dotaccent @ringaccent @ubaraccent @udotaccent
% Others are defined by plain TeX: @` @' @" @^ @~ @= @u @v @H.
\let\, = \c
\let\dotaccent = \.
\def\ringaccent#1{{\accent23 #1}}
\let\tieaccent = \t
\let\ubaraccent = \b
\let\udotaccent = \d
% Other special characters: @questiondown @exclamdown
% Plain TeX defines: @AA @AE @O @OE @L (plus lowercase versions) @ss.
\def\questiondown{?`}
\def\exclamdown{!`}
% Dotless i and dotless j, used for accents.
\def\imacro{i}
\def\jmacro{j}
\def\dotless#1{%
\def\temp{#1}%
\ifx\temp\imacro \ptexi
\else\ifx\temp\jmacro \j
\else \errmessage{@dotless can be used only with i or j}%
\fi\fi
}
% Be sure we're in horizontal mode when doing a tie, since we make space
% equivalent to this in @example-like environments. Otherwise, a space
% at the beginning of a line will start with \penalty -- and
% since \penalty is valid in vertical mode, we'd end up putting the
% penalty on the vertical list instead of in the new paragraph.
{\catcode`@ = 11
% Avoid using \@M directly, because that causes trouble
% if the definition is written into an index file.
\global\let\tiepenalty = \@M
\gdef\tie{\leavevmode\penalty\tiepenalty\ }
}
% @: forces normal size whitespace following.
\def\:{\spacefactor=1000 }
% @* forces a line break.
\def\*{\hfil\break\hbox{}\ignorespaces}
% @/ allows a line break.
\let\/=\allowbreak
% @. is an end-of-sentence period.
\def\.{.\spacefactor=3000 }
% @! is an end-of-sentence bang.
\def\!{!\spacefactor=3000 }
% @? is an end-of-sentence query.
\def\?{?\spacefactor=3000 }
% @w prevents a word break. Without the \leavevmode, @w at the
% beginning of a paragraph, when TeX is still in vertical mode, would
% produce a whole line of output instead of starting the paragraph.
\def\w#1{\leavevmode\hbox{#1}}
% @group ... @end group forces ... to be all on one page, by enclosing
% it in a TeX vbox. We use \vtop instead of \vbox to construct the box
% to keep its height that of a normal line. According to the rules for
% \topskip (p.114 of the TeXbook), the glue inserted is
% max (\topskip - \ht (first item), 0). If that height is large,
% therefore, no glue is inserted, and the space between the headline and
% the text is small, which looks bad.
%
% Another complication is that the group might be very large. This can
% cause the glue on the previous page to be unduly stretched, because it
% does not have much material. In this case, it's better to add an
% explicit \vfill so that the extra space is at the bottom. The
% threshold for doing this is if the group is more than \vfilllimit
% percent of a page (\vfilllimit can be changed inside of @tex).
%
\newbox\groupbox
\def\vfilllimit{0.7}
%
\def\group{\begingroup
\ifnum\catcode13=\active \else
\errhelp = \groupinvalidhelp
\errmessage{@group invalid in context where filling is enabled}%
\fi
%
% The \vtop we start below produces a box with normal height and large
% depth; thus, TeX puts \baselineskip glue before it, and (when the
% next line of text is done) \lineskip glue after it. (See p.82 of
% the TeXbook.) Thus, space below is not quite equal to space
% above. But it's pretty close.
\def\Egroup{%
\egroup % End the \vtop.
% \dimen0 is the vertical size of the group's box.
\dimen0 = \ht\groupbox \advance\dimen0 by \dp\groupbox
% \dimen2 is how much space is left on the page (more or less).
\dimen2 = \pageheight \advance\dimen2 by -\pagetotal
% if the group doesn't fit on the current page, and it's a big big
% group, force a page break.
\ifdim \dimen0 > \dimen2
\ifdim \pagetotal < \vfilllimit\pageheight
\page
\fi
\fi
\copy\groupbox
\endgroup % End the \group.
}%
%
\setbox\groupbox = \vtop\bgroup
% We have to put a strut on the last line in case the @group is in
% the midst of an example, rather than completely enclosing it.
% Otherwise, the interline space between the last line of the group
% and the first line afterwards is too small. But we can't put the
% strut in \Egroup, since there it would be on a line by itself.
% Hence this just inserts a strut at the beginning of each line.
\everypar = {\strut}%
%
% Since we have a strut on every line, we don't need any of TeX's
% normal interline spacing.
\offinterlineskip
%
% OK, but now we have to do something about blank
% lines in the input in @example-like environments, which normally
% just turn into \lisppar, which will insert no space now that we've
% turned off the interline space. Simplest is to make them be an
% empty paragraph.
\ifx\par\lisppar
\edef\par{\leavevmode \par}%
%
% Reset ^^M's definition to new definition of \par.
\obeylines
\fi
%
% Do @comment since we are called inside an environment such as
% @example, where each end-of-line in the input causes an
% end-of-line in the output. We don't want the end-of-line after
% the `@group' to put extra space in the output. Since @group
% should appear on a line by itself (according to the Texinfo
% manual), we don't worry about eating any user text.
\comment
}
%
% TeX puts in an \escapechar (i.e., `@') at the beginning of the help
% message, so this ends up printing `@group can only ...'.
%
\newhelp\groupinvalidhelp{%
group can only be used in environments such as @example,^^J%
where each line of input produces a line of output.}
% @need space-in-mils
% forces a page break if there is not space-in-mils remaining.
\newdimen\mil \mil=0.001in
\def\need{\parsearg\needx}
% Old definition--didn't work.
%\def\needx #1{\par %
%% This method tries to make TeX break the page naturally
%% if the depth of the box does not fit.
%{\baselineskip=0pt%
%\vtop to #1\mil{\vfil}\kern -#1\mil\nobreak
%\prevdepth=-1000pt
%}}
\def\needx#1{%
% Ensure vertical mode, so we don't make a big box in the middle of a
% paragraph.
\par
%
% If the @need value is less than one line space, it's useless.
\dimen0 = #1\mil
\dimen2 = \ht\strutbox
\advance\dimen2 by \dp\strutbox
\ifdim\dimen0 > \dimen2
%
% Do a \strut just to make the height of this box be normal, so the
% normal leading is inserted relative to the preceding line.
% And a page break here is fine.
\vtop to #1\mil{\strut\vfil}%
%
% TeX does not even consider page breaks if a penalty added to the
% main vertical list is 10000 or more. But in order to see if the
% empty box we just added fits on the page, we must make it consider
% page breaks. On the other hand, we don't want to actually break the
% page after the empty box. So we use a penalty of 9999.
%
% There is an extremely small chance that TeX will actually break the
% page at this \penalty, if there are no other feasible breakpoints in
% sight. (If the user is using lots of big @group commands, which
% almost-but-not-quite fill up a page, TeX will have a hard time doing
% good page breaking, for example.) However, I could not construct an
% example where a page broke at this \penalty; if it happens in a real
% document, then we can reconsider our strategy.
\penalty9999
%
% Back up by the size of the box, whether we did a page break or not.
\kern -#1\mil
%
% Do not allow a page break right after this kern.
\nobreak
\fi
}
% @br forces paragraph break
\let\br = \par
% @dots{} output an ellipsis using the current font.
% We do .5em per period so that it has the same spacing in a typewriter
% font as three actual period characters.
%
\def\dots{%
\leavevmode
\hbox to 1.5em{%
\hskip 0pt plus 0.25fil minus 0.25fil
.\hss.\hss.%
\hskip 0pt plus 0.5fil minus 0.5fil
}%
}
% @enddots{} is an end-of-sentence ellipsis.
%
\def\enddots{%
\leavevmode
\hbox to 2em{%
\hskip 0pt plus 0.25fil minus 0.25fil
.\hss.\hss.\hss.%
\hskip 0pt plus 0.5fil minus 0.5fil
}%
\spacefactor=3000
}
% @page forces the start of a new page.
%
\def\page{\par\vfill\supereject}
% @exdent text....
% outputs text on separate line in roman font, starting at standard page margin
% This records the amount of indent in the innermost environment.
% That's how much \exdent should take out.
\newskip\exdentamount
% This defn is used inside fill environments such as @defun.
\def\exdent{\parsearg\exdentyyy}
\def\exdentyyy #1{{\hfil\break\hbox{\kern -\exdentamount{\rm#1}}\hfil\break}}
% This defn is used inside nofill environments such as @example.
\def\nofillexdent{\parsearg\nofillexdentyyy}
\def\nofillexdentyyy #1{{\advance \leftskip by -\exdentamount
\leftline{\hskip\leftskip{\rm#1}}}}
% @inmargin{WHICH}{TEXT} puts TEXT in the WHICH margin next to the current
% paragraph. For more general purposes, use the \margin insertion
% class. WHICH is `l' or `r'.
%
\newskip\inmarginspacing \inmarginspacing=1cm
\def\strutdepth{\dp\strutbox}
%
\def\doinmargin#1#2{\strut\vadjust{%
\nobreak
\kern-\strutdepth
\vtop to \strutdepth{%
\baselineskip=\strutdepth
\vss
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