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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /macros/latex/contrib/fwlw/fwlw.sty
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+% F W L W . S T Y ( First Word, Last Word )
+%
+% Donald Arseneau (1993, 1995)
+%
+% The fwlw package provides a mechanism to determine the first and
+% last words on the current page, plus the first word on the *next*
+% page. These can be used in head-lines or foot-lines. The `words'
+% you see may not be real words, but any unbreakable object.
+%
+% Two pagestyles are defined to print these words: \pagestyle{NextWordFoot}
+% which helps you read ahead to the word on the next page; and \pagestyle
+% {fwlwhead} which is like the headers in a lexicon. Or you can use the
+% words in your own page-style. The words are made available in the box
+% registers:
+% \FirstWordBox - first word on this page
+% \NextWordBox - first word on next page
+% \LastWordBox - last word on this page
+% Use them in your header lines like: \usebox\LastWordBox.
+%
+% Such labelling does not make much sense when \chapter generates a page
+% break, so the last page before a \chapter (or any \clearpage) gets
+% a blank "next word", and the first page of the chapter gets a blank
+% "first word".
+%
+% Note that `words' may unfortunately be things like:
+% - two~words
+% - [ ]Word ( [ ] represents a parindent box)
+% - a whole displayed equation
+% - the first column of an aligned equation
+% - anomalously blank, if there are \writes or split footnotes etc.
+% - partial words like par- or -tial due to hyphenation.
+%
+% (Major digression...)
+% An entirely different approach is possible using \mark and \obeyspaces,
+% and would have different problems. The problems with catcode changes
+% may be more or less serious for your particular application. (You are
+% invited to write a package using that method!) The best solution would
+% involve \mark and an input filter program to
+% `\w{tag} \w{each} \w{word}, \w{in} \w{some} \w{way}.'
+% TeX has no \everyword hook to insert such tagging.
+%
+% Copyright (C) 1993,1995 by Donald Arseneau
+% Vancouver, Canada, email asnd@triumf.ca
+% This software package may be freely used, transmitted, reproduced,
+% or modified provided that this notice is left intact.
+%
+% Declare a "unique" penalty value as flag
+\mathchardef\LW@pen 12345
+
+% allocate box registers
+\newbox\FirstWordBox \global\setbox\FirstWordBox\hbox{}
+\newbox\NextWordBox \global\setbox\NextWordBox\hbox{}
+\newbox\LastWordBox \global\setbox\LastWordBox\hbox{}
+\newbox\LW@box \global\setbox\LW@box\hbox{}
+\newbox\LW@saved
+
+% pagestyle fwlwhead: header line hsa first word and last word
+\def\ps@fwlwhead{\let\@mkboth\@gobbletwo
+ \def\@oddhead{\if@fcolmade\else % no word-heads on float pages.
+ \usebox\FirstWordBox\hfil\usebox\LastWordBox\fi}%
+ \let\@evenhead\@oddhead
+ \let\@oddfoot\@empty\let\@evenfoot\@oddfoot
+ \let\chaptermark\@gobble\let\sectionmark\@gobble\let\subsectionmark\@gobble
+ }
+
+% pagestyle NextWordFoot: foot line has page number and next-page first word,
+% but only on odd pages
+\def\ps@NextWordFoot{\let\@mkboth\@gobbletwo
+ \let\@oddhead\@empty\let\@evenhead\@oddhead
+ \def\@oddfoot{\hfil\thepage\hfil\llap{\usebox\NextWordBox}}%
+ \let\@evenfoot\@empty
+ \let\chaptermark\@gobble\let\sectionmark\@gobble\let\subsectionmark\@gobble
+ }
+
+% Shell around old output routine. Gets first word from next page by
+% letting TeX continue with \vsize=0 to get a look at the next line.
+% Values of \outputpenalty for \specialoutput ( -10001 to -19999 ) are
+% simply run through the output routine.
+% \supereject and \clearpage give a blank "next word".
+% When called after making a stub-page the stub is returned to the
+% vertical list, the previous page is restored and shipped out normally,
+% but knowing what the next word will be.
+
+\edef\FWLWnorm@L@output{\the\output}
+
+\output{\@tempswafalse
+\ifnum \outputpenalty>-\@MM \ifnum\outputpenalty<-\@M \@tempswatrue\fi\fi
+\if@tempswa % special (float) output
+% \message{Float handler: penalty=\the\outputpenalty}%
+ \FWLWnorm@L@output
+\else
+ \ifvoid\LW@saved % end of real page
+% \message{End of real page}%
+ \global\setbox\LW@saved\copy\@cclv % save page
+ \setbox\@tempboxa\vbox{\unvbox\@cclv \unskip\unkern\unpenalty
+ \unskip\unkern\unpenalty \unskip\unkern\unpenalty
+ \setbox\@tempboxa\lastbox
+ \LW@getlast@word\@tempboxa\LastWordBox
+ }\ifnum\outputpenalty>-\@MM % not \supereject
+ \xdef\LW@vsize{\global\vsize\the\vsize
+ \global\holdinginserts\the\holdinginserts}%
+ \global\vsize\z@ \global\holdinginserts\@ne
+ \else % \supereject, just output, don't look for word on next page
+% \message{caused by super-eject.}
+ \global\setbox\@cclv\box\LW@saved
+ \global\setbox\NextWordBox\hbox{}%
+ \FWLWnorm@L@output
+ \global\setbox\FirstWordBox\box\NextWordBox
+ \fi
+ \else % saved page => just did tiny page to get next word
+% \message{Just got next line:}{\tracingall\showboxdepth2 \showbox\@cclv}%
+ \setbox\@tempboxa\vbox{\penalty\LW@pen\unvcopy\@cclv \LW@getall@boxes
+ \ifvbox\LW@box \penalty\LW@pen\unvbox\LW@box \LW@getall@boxes\fi
+ \ifvbox\LW@box \global\setbox\NextWordBox\hbox{}\else
+ \LW@getfirst@word\LW@box\NextWordBox
+ \fi}% Return tiny page to page list:
+ \unvbox\@cclv \ifnum\outputpenalty<\@M \penalty\outputpenalty\fi
+ \LW@vsize\relax
+ \global\setbox\@cclv\box\LW@saved
+ \FWLWnorm@L@output
+ \global\setbox\FirstWordBox\box\NextWordBox
+\fi\fi}
+
+% globally get last "word" from a box (#1) into another box (#2)
+\def\LW@getlast@word#1#2{\setbox\@tempboxa\vbox{\hsize\maxdimen \@parboxrestore
+ \hyphenpenalty\@M \exhyphenpenalty\@M
+ \rightskip\fill \looseness\@M \linepenalty\z@
+ \noindent\unhbox#1\endgraf
+ \unskip\unkern\unpenalty \global\setbox\LW@box\lastbox
+ }\LW@repack{#2}}
+
+% globally get first "word" from a box (#1) into another box (#2)
+\def\LW@getfirst@word#1#2{\setbox\@tempboxa\vbox{\@parboxrestore
+ \parshape\thr@@ \z@\z@ \z@\z@ \z@\maxdimen \parfillskip\fill
+ \hyphenpenalty\@M \exhyphenpenalty\@M
+ \hbadness\@MM \overfullrule\z@ \hfuzz\maxdimen
+ \ifhbox#1\noindent
+ \vadjust{\penalty\LW@pen}\penalty-\@M\unhbox#1% eliminate previous \leftskip
+ \else\ifvbox#1\penalty\LW@pen\unvbox#1\fi\fi
+ \endgraf
+ \@tempcnta\z@ \LW@getall@boxes}\LW@repack{#2}}
+
+% Go through a vertical list that starts with special penalty
+\def\LW@getall@boxes{\global\setbox\LW@box\lastbox \unskip\unkern \unskip\unkern
+ \let\@tempa\relax
+ \ifvoid \LW@box \advance\@tempcnta\@ne \else \@tempcnta\z@ \fi
+ \ifnum\lastpenalty=\LW@pen \else \unpenalty\fi
+ \ifnum\lastpenalty=\LW@pen \else \unpenalty\fi
+ \ifnum\lastpenalty=\LW@pen \else \ifnum\@tempcnta<5
+ \let\@tempa\LW@getall@boxes \fi \fi \unpenalty \@tempa}
+
+% Put contents of \LW@box into hbox #1
+\def\LW@repack#1{\global\setbox#1\hbox{\ifhbox\LW@box
+ \unhbox\LW@box\unskip\unskip\unpenalty\unskip
+ \else\ifvbox\LW@box\box\LW@box\fi\fi}}