% rail.sty - style file to support railroad diagrams

%

% 09-Jul-90 L. Rooijakkers

% 08-Oct-90 L. Rooijakkers	fixed centering bug when \rail@tmpc<0.

% 07-Feb-91 L. Rooijakkers	added \railoptions command, indexing

% 08-Feb-91 L. Rooijakkers	minor fixes

% 28-Jun-94 K. Barthelmann	turned into LaTeX2e package

% 08-Dec-96 K. Barthelmann	replaced \@writefile

% 13-Dec-96 K. Barthelmann	cleanup

%

% This style file needs to be used in conjunction with the 'rail'

% program. Running LaTeX as 'latex file' produces file.rai, which should be

% processed by Rail with 'rail file'. This produces file.rao, which will

% be picked up by LaTeX on the next 'latex file' run.

%

% LaTeX will warn if there is no file.rao or it's out of date.

%

% The macros in this file thus consist of two parts: those that read and

% write the .rai and .rao files, and those that do the actual formatting

% of the railroad diagrams.

\NeedsTeXFormat{LaTeX2e}

\ProvidesPackage{rail}[1996/12/13]

% railroad diagram formatting parameters (user level)

% all of these are copied into their internal versions by \railinit

%

% \railunit : \unitlength within railroad diagrams

% \railextra : extra length at outside of diagram

% \railboxheight : height of ovals and frames

% \railboxskip : vertical space between lines

% \railboxleft : space to the left of a box

% \railboxright : space to the right of a box

% \railovalspace : extra space around contents of oval

% \railframespace : extra space around contents of frame

% \railtextleft : space to the left of text

% \railtextright : space to the right of text

% \railtextup : space to lift text up

% \railjoinsize : circle size of join/split arcs

% \railjoinadjust : space to adjust join

%

% \railnamesep : separator between name and rule body

\newlength\railunit

\newlength\railextra

\newlength\railboxheight

\newlength\railboxskip

\newlength\railboxleft

\newlength\railboxright

\newlength\railovalspace

\newlength\railframespace

\newlength\railtextleft

\newlength\railtextright

\newlength\railtextup

\newlength\railjoinsize

\newlength\railjoinadjust

\newlength\railnamesep

% initialize the parameters

\setlength\railunit{1sp}

\setlength\railextra{4ex}

\setlength\railboxleft{1ex}

\setlength\railboxright{1ex}

\setlength\railovalspace{2ex}

\setlength\railframespace{2ex}

\setlength\railtextleft{1ex}

\setlength\railtextright{1ex}

\setlength\railjoinadjust{0pt}

\setlength\railnamesep{1ex}

\DeclareOption{10pt}{

  \setlength\railboxheight{16pt}

  \setlength\railboxskip{24pt}

  \setlength\railtextup{5pt}

  \setlength\railjoinsize{16pt}

}

\DeclareOption{11pt}{

  \setlength\railboxheight{16pt}

  \setlength\railboxskip{24pt}

  \setlength\railtextup{5pt}

  \setlength\railjoinsize{16pt}

}

\DeclareOption{12pt}{

  \setlength\railboxheight{20pt}

  \setlength\railboxskip{28pt}

  \setlength\railtextup{6pt}

  \setlength\railjoinsize{20pt}

}

\ExecuteOptions{10pt}

\ProcessOptions

% internal versions of the formatting parameters

%

% \rail@extra   : \railextra

% \rail@boxht   : \railboxheight

% \rail@boxsp   : \railboxskip

% \rail@boxlf   : \railboxleft

% \rail@boxrt   : \railboxright

% \rail@boxhht  : \railboxheight / 2

% \rail@ovalsp  : \railovalspace

% \rail@framesp : \railframespace

% \rail@textlf	: \railtextleft

% \rail@textrt	: \railtextright

% \rail@textup	: \railtextup

% \rail@joinsz  : \railjoinsize

% \rail@joinhsz : \railjoinsize / 2

% \rail@joinadj : \railjoinadjust

%

% \railinit : internalize all of the parameters.

\newcount\rail@extra

\newcount\rail@boxht

\newcount\rail@boxsp

\newcount\rail@boxlf

\newcount\rail@boxrt

\newcount\rail@boxhht

\newcount\rail@ovalsp

\newcount\rail@framesp

\newcount\rail@textlf

\newcount\rail@textrt

\newcount\rail@textup

\newcount\rail@joinsz

\newcount\rail@joinhsz

\newcount\rail@joinadj

\newcommand\railinit{

\rail@extra=\railextra

\divide\rail@extra by \railunit

\rail@boxht=\railboxheight

\divide\rail@boxht by \railunit

\rail@boxsp=\railboxskip

\divide\rail@boxsp by \railunit

\rail@boxlf=\railboxleft

\divide\rail@boxlf by \railunit

\rail@boxrt=\railboxright

\divide\rail@boxrt by \railunit

\rail@boxhht=\railboxheight

\divide\rail@boxhht by \railunit

\divide\rail@boxhht by 2

\rail@ovalsp=\railovalspace

\divide\rail@ovalsp by \railunit

\rail@framesp=\railframespace

\divide\rail@framesp by \railunit

\rail@textlf=\railtextleft

\divide\rail@textlf by \railunit

\rail@textrt=\railtextright

\divide\rail@textrt by \railunit

\rail@textup=\railtextup

\divide\rail@textup by \railunit

\rail@joinsz=\railjoinsize

\divide\rail@joinsz by \railunit

\rail@joinhsz=\railjoinsize

\divide\rail@joinhsz by \railunit

\divide\rail@joinhsz by 2

\rail@joinadj=\railjoinadjust

\divide\rail@joinadj by \railunit

}

\AtBeginDocument{\railinit}

% \rail@param : declarations for list environment

%

% \railparam{TEXT} : sets \rail@param to TEXT

\def\rail@param{}

\newcommand\railparam[1]{

\def\rail@param{#1}

}

% \rail@tokenfont : format setup for \railtoken identifiers

%

% \rail@termfont : format setup for terminals

%

% \rail@nontfont : format setup for nonterminals

%

% \rail@annofont : format setup for annotations

%

% \rail@rulefont : format setup for rule names

%

% \rail@indexfont : format setup for index entry

%

% \railtermfont{TEXT} : set terminal format setup to TEXT

%

% \railnontermfont{TEXT} : set nonterminal format setup to TEXT

%

% \railannotatefont{TEXT} : set annotation format setup to TEXT

%

% \railnamefont{TEXT} : set rule name format setup to TEXT

%

% \railindexfont{TEXT} : set index entry format setup to TEXT

\def\rail@termfont{\ttfamily\upshape}

\def\rail@nontfont{\rmfamily\upshape}

\def\rail@annofont{\rmfamily\itshape}

\def\rail@namefont{\rmfamily\itshape}

\def\rail@indexfont{\rmfamily\itshape}

\newcommand\railtermfont[1]{

\def\rail@termfont{#1}

}

\newcommand\railnontermfont[1]{

\def\rail@nontfont{#1}

}

\newcommand\railannotatefont[1]{

\def\rail@annofont{#1}

}

\newcommand\railnamefont[1]{

\def\rail@namefont{#1}

}

\newcommand\railindexfont[1]{

\def\rail@indexfont{#1}

}

% railroad read/write macros

%

% \begin{rail} TEXT \end{rail} : TEXT is written out to the .rai file,

%                                as \rail@i{NR}{TEXT}. Then the matching

%                                \rail@o{NR}{FMT} from the .rao file is

%                                executed (if defined).

%

% \railoptions{OPTIONS} : OPTIONS are written out to the .rai file,

%                         as \rail@p{OPTIONS}.

%

% \railterm{IDENT,IDENT,...} : format IDENT as terminals. writes out

%                              \rail@t{IDENT} to the .rai file

%

% \railalias{IDENT}{TEXT} : format IDENT as TEXT. defines \rail@t@IDENT as

%                           TEXT.

%

% \rail@nr : railroad diagram counter

%

% \ifrail@match : current \rail@i{NR}{TEXT} matches

%

% \rail@first :	actions to be done first. read in .rao file,

%               open .rai file if \@filesw true, undefine \rail@first.

%               executed from \begin{rail} and \railtoken.

%

% \rail@i{NR}{TEXT} : defines \rail@i@NR as TEXT. written to the .rai

%                     file by \rail, read from the .rao file by

%                     \rail@first

%

% \rail@t{IDENT} : tells Rail that IDENT is to be custom formatted,

%                  written to the .rai file by \railterm.

%

% \rail@o{NR}{TEXT} : defines \rail@o@NR as TEXT, read from the .rao

%                     file by \rail@first.

%

% \rail@p{OPTIONS} : pass options to rail, written to the .rai file by

%                    \railoptions

%

% \rail@write{TEXT} : write TEXT to the .rai file

%

% \rail@warn : warn user for mismatching diagrams

%

% \rail@endwarn : either \relax or \rail@warn

%

% \ifrail@all : checked at the end of the document

\newcount\rail@nr

\newif\ifrail@all

\rail@alltrue

\newif\ifrail@match

\def\rail@first{

\makeatletter

\InputIfFileExists{\jobname.rao}{}{\PackageInfo{rail}{No file \jobname.rao}}

\makeatother

\if@filesw

\newwrite\tf@rai

\immediate\openout\tf@rai=\jobname.rai

\fi

\global\let\rail@first=\relax

}

\long\def\rail@body#1\end{

\begingroup

\let\\=\relax

\xdef\rail@i@{#1}

\rail@write{\string\rail@i{\number\rail@nr}{\rail@i@}}

\endgroup

\end

}

\newenvironment{rail}{

\global\advance\rail@nr by 1

\rail@first

\rail@body

}{

\rail@matchtrue

\@ifundefined{rail@o@\number\rail@nr}{\rail@matchfalse}{}

\expandafter\ifx\csname rail@i@\number\rail@nr\endcsname\rail@i@

\else

\rail@matchfalse

\fi

\ifrail@match

\csname rail@o@\number\rail@nr\endcsname

\else

\PackageWarning{rail}{Railroad diagram {\number\rail@nr} doesn't match}

\global\let\rail@endwarn=\rail@warn

\begin{list}{}{\rail@param}

\rail@begin{1}{}

\rail@setbox{\bfseries ???}

\rail@oval

\rail@end

\end{list}

\fi

}

\newcommand\railoptions[1]{

\rail@first

\rail@write{\string\rail@p{#1}}

}

\newcommand\railterm[1]{

\rail@first

\@for\rail@@:=#1\do{

\rail@write{\string\rail@t{\rail@@}}

}

}

\newcommand\railalias[2]{

\expandafter\def\csname rail@t@#1\endcsname{#2}

}

\long\def\rail@i#1#2{

\expandafter\gdef\csname rail@i@#1\endcsname{#2}

}

\def\rail@o#1#2{

\expandafter\gdef\csname rail@o@#1\endcsname{

\begin{list}{}{\rail@param}#2\end{list}

}

}

\def\rail@t#1{}

\def\rail@p#1{}

\def\rail@write#1{\@ifundefined{tf@rai}{}{\immediate\write\tf@rai{#1}}}

\def\rail@warn{

\PackageWarningNoLine{rail}{Railroad diagram(s) may have changed.

                            Use 'rail' and rerun}

}

\let\rail@endwarn=\relax

\AtEndDocument{\rail@endwarn}

% index entry macro

%

% \rail@index{IDENT} : add index entry for IDENT

\def\rail@index#1{

\index{\rail@indexfont#1}

}

% railroad formatting primitives

%

% \rail@x : current x

% \rail@y : current y

% \rail@ex : current end x

% \rail@sx : starting x for \rail@cr

% \rail@rx : rightmost previous x for \rail@cr

%

% \rail@tmpa : temporary count

% \rail@tmpb : temporary count

% \rail@tmpc : temporary count

%

% \rail@put : put at (\rail@x,\rail@y)

%

% \rail@eline : end line by drawing from \rail@ex to \rail@x

%

% \rail@sety{LEVEL} : set \rail@y to level LEVEL

\newcount\rail@x

\newcount\rail@y

\newcount\rail@ex

\newcount\rail@sx

\newcount\rail@rx

\newcount\rail@tmpa

\newcount\rail@tmpb

\newcount\rail@tmpc

\def\rail@put{\put(\number\rail@x,\number\rail@y)}

\def\rail@eline{

\rail@tmpb=\rail@x

\advance\rail@tmpb by -\rail@ex

\rail@put{\line(-1,0){\number\rail@tmpb}}

}

\def\rail@sety#1{

\rail@y=#1

\multiply\rail@y by -\rail@boxsp

\advance\rail@y by -\rail@boxht

}

% \rail@begin{HEIGHT}{NAME} : begin a railroad diagram of height HEIGHT

%

% \rail@end : end a railroad diagram

%

% \rail@expand{IDENT} : expand IDENT

\def\rail@begin#1#2{

\item[]

\begin{minipage}[t]{\linewidth}

\ifx\@empty#2\else

{\rail@namefont \rail@expand{#2}}\\*[\railnamesep]

\fi

\unitlength=\railunit

\rail@tmpa=#1

\multiply\rail@tmpa by \rail@boxsp

\begin{picture}(0,\number\rail@tmpa)(0,-\number\rail@tmpa)

\rail@ex=0

\rail@rx=0

\rail@x=\rail@extra

\rail@sx=\rail@x

\rail@sety{0}

}

\def\rail@end{

\advance\rail@x by \rail@extra

\rail@eline

\end{picture}

\end{minipage}

}

\def\rail@expand#1{\@ifundefined{rail@t@#1}{#1}{\csname rail@t@#1\endcsname}}

% \rail@token{TEXT}[ANNOT] : format token TEXT with annotation

%

% \rail@ctoken{TEXT}[ANNOT] : format token TEXT centered with annotation

%

% \rail@nont{TEXT}[ANNOT] : format nonterminal TEXT with annotation

%

% \rail@cnont{TEXT}[ANNOT] : format nonterminal TEXT centered with annotation

%

% \rail@term{TEXT}[ANNOT] : format terminal TEXT with annotation

%

% \rail@cterm{TEXT}[ANNOT] : format terminal TEXT centered with annotation

%

% \rail@annote[TEXT] : format TEXT as annotation

\def\rail@token#1[#2]{

\rail@setbox{%

{\rail@termfont \rail@expand{#1}}\ifx\@empty#2\else\ {\rail@annofont #2}\fi

}

\rail@oval

}

\def\rail@ctoken#1[#2]{

\rail@setbox{%

{\rail@termfont \rail@expand{#1}}\ifx\@empty#2\else\ {\rail@annofont #2}\fi

}

\rail@coval

}

\def\rail@nont#1[#2]{

\rail@setbox{%

{\rail@nontfont \rail@expand{#1}}\ifx\@empty#2\else\ {\rail@annofont #2}\fi

}

\rail@frame

}

\def\rail@cnont#1[#2]{

\rail@setbox{%

{\rail@nontfont \rail@expand{#1}}\ifx\@empty#2\else\ {\rail@annofont #2}\fi

}

\rail@cframe

}

\def\rail@term#1[#2]{

\rail@setbox{%

{\rail@termfont #1}\ifx\@empty#2\else\ {\rail@annofont #2}\fi

}

\rail@oval

}

\def\rail@cterm#1[#2]{

\rail@setbox{%

{\rail@termfont #1}\ifx\@empty#2\else\ {\rail@annofont #2}\fi

}

\rail@coval

}

\def\rail@annote[#1]{

\rail@setbox{\rail@annofont #1}

\rail@text

}

% \rail@box : temporary box for \rail@oval and \rail@frame

%

% \rail@setbox{TEXT} : set \rail@box to TEXT, set \rail@tmpa to width

%

% \rail@oval : format \rail@box of width \rail@tmpa inside an oval

%

% \rail@coval : same as \rail@oval, but centered between \rail@x and

%               \rail@mx

%

% \rail@frame : format \rail@box of width \rail@tmpa inside a frame

%

% \rail@cframe : same as \rail@frame, but centered between \rail@x and

%                \rail@mx

%

% \rail@text : format \rail@box of width \rail@tmpa above the line

\newbox\rail@box

\def\rail@setbox#1{

\setbox\rail@box\hbox{\strut#1}

\rail@tmpa=\wd\rail@box

\divide\rail@tmpa by \railunit

}

\def\rail@oval{

\advance\rail@x by \rail@boxlf

\rail@eline

\advance\rail@tmpa by \rail@ovalsp

\ifnum\rail@tmpa<\rail@boxht\rail@tmpa=\rail@boxht\fi

\rail@tmpb=\rail@tmpa

\divide\rail@tmpb by 2

\advance\rail@y by -\rail@boxhht

\rail@put{\makebox(\number\rail@tmpa,\number\rail@boxht){\box\rail@box}}

\advance\rail@y by \rail@boxhht

\advance\rail@x by \rail@tmpb

\rail@put{\oval(\number\rail@tmpa,\number\rail@boxht)}

\advance\rail@x by \rail@tmpb

\rail@ex=\rail@x

\advance\rail@x by \rail@boxrt

}

\def\rail@coval{

\rail@tmpb=\rail@tmpa

\advance\rail@tmpb by \rail@ovalsp

\ifnum\rail@tmpb<\rail@boxht\rail@tmpb=\rail@boxht\fi

\advance\rail@tmpb by \rail@boxlf

\advance\rail@tmpb by \rail@boxrt

\rail@tmpc=\rail@mx

\advance\rail@tmpc by -\rail@x

\advance\rail@tmpc by -\rail@tmpb

\divide\rail@tmpc by 2

\ifnum\rail@tmpc>0

\advance\rail@x by \rail@tmpc

\fi

\rail@oval

}

\def\rail@frame{

\advance\rail@x by \rail@boxlf

\rail@eline

\advance\rail@tmpa by \rail@framesp

\ifnum\rail@tmpa<\rail@boxht\rail@tmpa=\rail@boxht\fi

\advance\rail@y by -\rail@boxhht

\rail@put{\framebox(\number\rail@tmpa,\number\rail@boxht){\box\rail@box}}

\advance\rail@y by \rail@boxhht

\advance\rail@x by \rail@tmpa

\rail@ex=\rail@x

\advance\rail@x by \rail@boxrt

}

\def\rail@cframe{

\rail@tmpb=\rail@tmpa

\advance\rail@tmpb by \rail@framesp

\ifnum\rail@tmpb<\rail@boxht\rail@tmpb=\rail@boxht\fi

\advance\rail@tmpb by \rail@boxlf

\advance\rail@tmpb by \rail@boxrt

\rail@tmpc=\rail@mx

\advance\rail@tmpc by -\rail@x

\advance\rail@tmpc by -\rail@tmpb

\divide\rail@tmpc by 2

\ifnum\rail@tmpc>0

\advance\rail@x by \rail@tmpc

\fi

\rail@frame

}

\def\rail@text{

\advance\rail@x by \rail@textlf

\advance\rail@y by \rail@textup

\rail@put{\box\rail@box}

\advance\rail@y by -\rail@textup

\advance\rail@x by \rail@tmpa

\advance\rail@x by \rail@textrt

}

% alternatives

%

% \rail@jx \rail@jy : current join point

%

% \rail@gx \rail@gy \rail@gex \rail@grx : global versions of \rail@x etc,

%                                         to pass values over group closings

%

% \rail@mx : maximum x so far

%

% \rail@sy : starting \rail@y for alternatives

%

% \rail@jput : put at (\rail@jx,\rail@jy)

%

% \rail@joval[PART] : put \oval[PART] with adjust

\newcount\rail@jx

\newcount\rail@jy

\newcount\rail@gx

\newcount\rail@gy

\newcount\rail@gex

\newcount\rail@grx

\newcount\rail@sy

\newcount\rail@mx

\def\rail@jput{

\put(\number\rail@jx,\number\rail@jy)

}

\def\rail@joval[#1]{

\advance\rail@jx by \rail@joinadj

\rail@jput{\oval(\number\rail@joinsz,\number\rail@joinsz)[#1]}

\advance\rail@jx by -\rail@joinadj

}

% \rail@barsplit : incoming split for '|'

%

% \rail@plussplit : incoming split for '+'

%

\def\rail@barsplit{

\advance\rail@jy by -\rail@joinhsz

\rail@joval[tr]

\advance\rail@jx by \rail@joinhsz

}

\def\rail@plussplit{

\advance\rail@jy by -\rail@joinhsz

\advance\rail@jx by \rail@joinsz

\rail@joval[tl]

\advance\rail@jx by -\rail@joinhsz

}

% \rail@alt{SPLIT} : start alternatives with incoming split SPLIT

%

\def\rail@alt#1{

\rail@sy=\rail@y

\rail@jx=\rail@x

\rail@jy=\rail@y

\advance\rail@x by \rail@joinsz

\rail@mx=0

\let\rail@list=\@empty

\let\rail@comma=\@empty

\let\rail@split=#1

\begingroup

\rail@sx=\rail@x

\rail@rx=0

}

% \rail@nextalt{FIX}{Y} : start next alternative at vertical position Y

%                         and fix-up FIX

%

\def\rail@nextalt#1#2{

\global\rail@gx=\rail@x

\global\rail@gy=\rail@y

\global\rail@gex=\rail@ex

\global\rail@grx=\rail@rx

\endgroup

#1

\ifnum\rail@gx>\rail@mx\rail@mx=\rail@gx\fi

\ifnum\rail@grx>\rail@mx\rail@mx=\rail@grx\fi

\edef\rail@list{\rail@list\rail@comma\number\rail@gex:\number\rail@gy}

\def\rail@comma{,}

\rail@split

\let\rail@split=\@empty

\rail@sety{#2}

\rail@tmpa=\rail@jy

\advance\rail@tmpa by -\rail@y

\advance\rail@tmpa by -\rail@joinhsz

\rail@jput{\line(0,-1){\number\rail@tmpa}}

\rail@jy=\rail@y

\advance\rail@jy by \rail@joinhsz

\advance\rail@jx by \rail@joinhsz

\rail@joval[bl]

\advance\rail@jx by -\rail@joinhsz

\rail@ex=\rail@x

\begingroup

\rail@sx=\rail@x

\rail@rx=0

}

% \rail@barjoin : outgoing join for first '|' alternative

%

% \rail@plusjoin : outgoing join for first '+' alternative

%

% \rail@altjoin : join for subsequent alternative

%

\def\rail@barjoin{

\ifnum\rail@y<\rail@sy

\global\rail@gex=\rail@jx

\else

\global\rail@gex=\rail@ex

\fi

\advance\rail@jy by -\rail@joinhsz

\rail@joval[tl]

\advance\rail@jx by -\rail@joinhsz

\ifnum\rail@y<\rail@sy

\rail@altjoin

\fi

}

\def\rail@plusjoin{

\global\rail@gex=\rail@ex

\advance\rail@jy by -\rail@joinhsz

\advance\rail@jx by -\rail@joinsz

\rail@joval[tr]

\advance\rail@jx by \rail@joinhsz

}

\def\rail@altjoin{

\rail@eline

\rail@tmpa=\rail@jy

\advance\rail@tmpa by -\rail@y

\advance\rail@tmpa by -\rail@joinhsz

\rail@jput{\line(0,-1){\number\rail@tmpa}}

\rail@jy=\rail@y

\advance\rail@jy by \rail@joinhsz

\advance\rail@jx by -\rail@joinhsz

\rail@joval[br]

\advance\rail@jx by \rail@joinhsz

}

% \rail@eltsplit EX:Y; : split EX:Y into \rail@ex \rail@y

%

% \rail@endalt{JOIN} : end alternatives with outgoing join JOIN

\def\rail@eltsplit#1:#2;{\rail@ex=#1\rail@y=#2}

\def\rail@endalt#1{

\global\rail@gx=\rail@x

\global\rail@gy=\rail@y

\global\rail@gex=\rail@ex

\global\rail@grx=\rail@rx

\endgroup

\ifnum\rail@gx>\rail@mx\rail@mx=\rail@gx\fi

\ifnum\rail@grx>\rail@mx\rail@mx=\rail@grx\fi

\edef\rail@list{\rail@list\rail@comma\number\rail@gex:\number\rail@gy}

\rail@x=\rail@mx

\rail@jx=\rail@x

\rail@jy=\rail@sy

\advance\rail@jx by \rail@joinsz

\let\rail@join=#1

\@for\rail@elt:=\rail@list\do{

\expandafter\rail@eltsplit\rail@elt;

\rail@join

\let\rail@join=\rail@altjoin

}

\rail@x=\rail@mx

\rail@y=\rail@sy

\rail@ex=\rail@gex

\advance\rail@x by \rail@joinsz

}

% \rail@bar : start '|' alternatives

%

% \rail@nextbar : next '|' alternative

%

% \rail@endbar : end '|' alternatives

%

\def\rail@bar{

\rail@alt\rail@barsplit

}

\def\rail@nextbar{

\rail@nextalt\relax

}

\def\rail@endbar{

\rail@endalt\rail@barjoin

}

% \rail@plus : start '+' alternatives

%

% \rail@nextplus: next '+' alternative

%

% \rail@endplus : end '+' alternatives

%

\def\rail@plus{

\rail@alt\rail@plussplit

}

\def\rail@nextplus{

\rail@nextalt\rail@fixplus

}

\def\rail@fixplus{

\ifnum\rail@gy<\rail@sy

\begingroup

\rail@x=\rail@gx

\rail@y=\rail@gy

\rail@ex=\rail@gex

\rail@rx=\rail@grx

\ifnum\rail@x<\rail@rx

\rail@x=\rail@rx

\fi

\rail@eline

\rail@jx=\rail@x

\rail@jy=\rail@y

\advance\rail@jy by \rail@joinhsz

\rail@joval[br]

\advance\rail@jx by \rail@joinhsz

\rail@tmpa=\rail@sy

\advance\rail@tmpa by -\rail@joinhsz

\advance\rail@tmpa by -\rail@jy

\rail@jput{\line(0,1){\number\rail@tmpa}}

\rail@jy=\rail@sy

\advance\rail@jy by -\rail@joinhsz

\advance\rail@jx by \rail@joinhsz

\rail@joval[tl]

\advance\rail@jy by \rail@joinhsz

\global\rail@gx=\rail@jx

\global\rail@gy=\rail@jy

\global\rail@gex=\rail@gx

\global\rail@grx=\rail@rx

\endgroup

\fi

}

\def\rail@endplus{

\rail@endalt\rail@plusjoin

}

% \rail@cr{Y} : carriage return to vertical position Y

\def\rail@cr#1{

\rail@tmpa=\rail@sx

\advance\rail@tmpa by \rail@joinsz

\ifnum\rail@x<\rail@tmpa\rail@x=\rail@tmpa\fi

\rail@eline

\rail@jx=\rail@x

\rail@jy=\rail@y

\advance\rail@x by \rail@joinsz

\ifnum\rail@x>\rail@rx\rail@rx=\rail@x\fi

\advance\rail@jy by -\rail@joinhsz

\rail@joval[tr]

\advance\rail@jx by \rail@joinhsz

\rail@sety{#1}

\rail@tmpa=\rail@jy

\advance\rail@tmpa by -\rail@y

\advance\rail@tmpa by -\rail@boxsp

\advance\rail@tmpa by -\rail@joinhsz

\rail@jput{\line(0,-1){\number\rail@tmpa}}

\rail@jy=\rail@y

\advance\rail@jy by \rail@boxsp

\advance\rail@jy by \rail@joinhsz

\advance\rail@jx by -\rail@joinhsz

\rail@joval[br]

\advance\rail@jy by -\rail@joinhsz

\rail@tmpa=\rail@jx

\advance\rail@tmpa by -\rail@sx

\advance\rail@tmpa by -\rail@joinhsz

\rail@jput{\line(-1,0){\number\rail@tmpa}}

\rail@jx=\rail@sx

\advance\rail@jx by \rail@joinhsz

\advance\rail@jy by -\rail@joinhsz

\rail@joval[tl]

\advance\rail@jx by -\rail@joinhsz

\rail@tmpa=\rail@boxsp

\advance\rail@tmpa by -\rail@joinsz

\rail@jput{\line(0,-1){\number\rail@tmpa}}

\advance\rail@jy by -\rail@tmpa

\advance\rail@jx by \rail@joinhsz

\rail@joval[bl]

\rail@x=\rail@jx

\rail@ex=\rail@x

}