added examiners

[lectures/latex.git] / nlsop / graphs.sty

\ProvidesPackage{graphs}[2000/12/19]
%
%
%_________________________________________________________________%%
% Draw graphs only if this is set to TRUE:
%_________________________________________________________________%%
%
\newif\ifdrawgraphs
\drawgraphstrue

\DeclareOption{draft}{\drawgraphsfalse}
\ProcessOptions

\typeout{}
\typeout{LaTeX2e package `graphs', version 1.53}
\typeout{Frank Drewes, University of Bremen, 19.12.2000}
\typeout{}

%
% \input the low-level commands that produce PostScript \special's.
%
\input{graphs_ps}
%
% \input the local configuration.
%
\input{graphs_config}
%
%
%_________________________________________________________________%%
% Initial value of \unitlength:
%
\newdimen\g@oldunitlength
\unitlength=1cm
%
%
%_________________________________________________________________%%
% Global settings and macros to change them (all lengths are numbers
% interpreted as multiples of \unitlength, except for the ones in
% \graphlinedash):
%
% - \graphlinewidth     define the width of lines (relevant
%                       for nodes and edges)
% - \graphlinedash      define the dash style of lines; the argument
%                       is a sequence of natural numbers delimited by
%                       blanks (relevant for nodes and edges). Is
%                       taken as input to the postscript setdash
%                       command.
% - \graphnodesize      define the size (= diameter) of nodes
% - \graphnodecolour    define the interior shading of nodes (a
%                       number between 0 (= black) and 1 (= white))
% - \fillednodestrue
%   \fillednodesfalse   determine whether the interior of nodes shall be
%                       filled or not
% - \graphlinecolour    define the `colour' of edges; similar to
%                       \graphnodecolour
% - \grapharrowlength   define the length from tip to basis of a
%                       directed edge's arrow head
% - \grapharrowwidth    define the width of the basis of a
%                       directed edge's arrow head (in multiples of
%                       \grapharrowlength)
% - \grapharrowtype     define the type of the arrow heads (argument
%                       should be 1 or 2)
% - \autodistance       define the factor that defines the distance
%                       of automatically placed text boxes from the
%                       centre of a node (1 means "placed on the
%                       edge").
% - \enlargeboxes       define the length that is added to
%                       text boxes (in x and y direction) in order
%                       to determine the size of the necessary
%                       white area underlying it.
% - \opaquetexttrue
%   \opaquetextfalse    determine whether text boxes shall be considered
%                       opaque or transparent (In the latter case
%                       \enlargeboxes doesn't have a (visible)
%                       effect.) Its initial value is true except
%                       for \autonodetext, which always has it set
%                       to false if it's not changed explicitely
%                       through the optional parameter. 
% - \filledareastrue
%   \filledareasfalse   determine whether areas shall be filled or not
%
% - \graphfillcolour    define the fill colour of areas (if filled
%                       at all).
%                       
%_________________________________________________________________%%
%
\def\g@defrel#1*#2{\edef#1{#1\ps@s #2 0 ge {#2 mul} if}}
\def\g@defplus#1+#2{\edef#1{
        #1\ps@s
        #2 1 gt
        {1 exch sub #2 div 1 exch sub}
        {#2 0 ge {#2 mul} if}
        ifelse}}
\def\g@defcolplus#1+#2{\edef#1{
        #1
        3 {
            3 1 roll
            #2 1 gt
            {1 exch sub #2 div 1 exch sub}
            {#2 0 ge {#2 mul} if}
            ifelse
          }
        repeat
}}
\def\g@defabs#1#2#3{\def#1{#3}\def#2{}}
\def\g@defcolabs#1#2{%
        \@ifnextchar({\g@defcolabsrgb{#1}{#2}}{\g@defcolabsbw{#1}{#2}}%
}
\def\g@defcolabsbw#1#2#3{\def#1{#3\ps@s #3\ps@s #3}\def#2{}}
\def\g@defcolabsrgb#1#2(#3,#4,#5){\def#1{#3\ps@s #4\ps@s #5}\def#2{}}
%
\def\graphlinewidth{%
        \@ifnextchar*{\g@defrel{\g@lwidthmod}}%
                        {\g@defabs{\g@lwidth}{\g@lwidthmod}}}
\graphlinewidth{.02}
%
\def\graphlinedash#1{\def\g@ldash{[ #1 ]}}
\graphlinedash{}
%
\def\graphnodesize#1{\def\g@nsize{#1}}
\graphnodesize{.2}
%
\def\graphnodecolour{%
        \@ifnextchar+{\g@defcolplus{\g@ncolourmod}}%
                        {\g@defcolabs{\g@ncolour}{\g@ncolourmod}}}
\graphnodecolour{0}
%
\newif\iffillednodes\fillednodestrue
%
\def\graphlinecolour{%
        \@ifnextchar+{\g@defcolplus{\g@lcolourmod}}%
                        {\g@defcolabs{\g@lcolour}{\g@lcolourmod}}}
\graphlinecolour{0}
%
\def\grapharrowlength{%
        \@ifnextchar*{\g@defrel{\g@alengthmod}}%
                        {\g@defabs{\g@alength}{\g@alengthmod}}}
\grapharrowlength{.3}
%
\def\grapharrowwidth{%
        \@ifnextchar*{\g@defrel{\g@awidthmod}}%
                        {\g@defabs{\g@awidth}{\g@awidthmod}}}
\grapharrowwidth{.5}
%
\def\grapharrowtype#1{\def\g@atype{#1}}
\grapharrowtype{1}
%
\def\autodistance#1{\def\g@autodistance{#1}}
\autodistance{1.3}
%
\def\enlargeboxes#1{\def\g@eboxes{#1}}
\enlargeboxes{.1}
%
\newif\ifopaquetext\opaquetexttrue
%
\newif\iffilledareas\filledareastrue
%
\def\graphfillcolour{%
        \@ifnextchar+{\g@defcolplus{\g@fcolourmod}}%
                        {\g@defcolabs{\g@fcolour}{\g@fcolourmod}}}
\graphfillcolour{.5}
%
%
%_________________________________________________________________%%
% Issue a warning if a command name defined in graphs.sty already has
% a meaning.
%_________________________________________________________________%%
%
\def\g@test#1{
        \@ifundefined{#1}{}{
          \typeout{}
          \typeout{Warning: command name `#1' already used;
                redefined in graphs.sty!}
          \typeout{}
        }
}
%
%
%_________________________________________________________________%%
% This is the environment in which the macros above can be used.
%
% Arguments:
%
% As for the LaTeX picture environment, i.e., it starts with
% \begin{graph}(x,y)(dx,dy) (where the second pair is optional) and
% ends with \end{graph}.
%
% Remark:
%
% The graph enviroment is imlemented on the basis of the picture
% environment. As a result, all commands allowed in pictures may be
% used (in addition to the graph commands). The picture commands'
% effects will always take place first, so subsequent AS WELL AS
% PRECEEDING graph commands will overlay the ordinary LaTeX
% picture. (This is one reason why a command like \freetext is NOT
% useless: its effect takes place after nodes and edges have been
% drawn.)
%_________________________________________________________________%%
%
\g@test{graph}\g@test{framegraph}
\def\framegraph(#1){\@ifnextchar({\g@graph f(#1)}{\g@graph f(#1)(0,0)}}
\def\graph(#1){\@ifnextchar({\g@graph n(#1)}{\g@graph n(#1)(0,0)}}
\def\g@graph#1(#2)(#3){%
        \begin{picture}(#2)(#3)%
        \if #1f%
          \put(#3){\framebox(#2){}}%
        \fi%
        \ifdrawgraphs\else%
          \put(#3){\framebox(#2){graph}}%
        \fi%
        \def\g@nodeinfo{}\def\g@specialeffects{}\def\g@nodes{}\def\g@texts{}%
        \def\g@edges{}%
}
\def\endgraph{%
        \ifdrawgraphs
          \g@nodeinfo\g@specialeffects\g@edges\g@nodes\g@texts%
        \fi%
        \end{picture}%
}
\def\endframegraph{\endgraph}
%
%
%_________________________________________________________________%%
% Types of nodes
%_________________________________________________________________%%
%
\def\g@circletype{0}
\def\g@rectangletype{1}
%
%
%_________________________________________________________________%%
% Definition of square nodes:
%
% Arguments:
%
% Nodename (a character sequence like abc)
% Position (x,y) = a pair of numbers
%_________________________________________________________________%%
%
\g@test{squarenode}
\def\squarenode#1(#2,#3){
        \@ifnextchar[{\g@squarenode{#1}(#2,#3)}{\g@squarenode{#1}(#2,#3)[]}
}
%
\def\g@squarenode#1(#2,#3)[#4]{
        \g@extendlist\g@nodeinfo{\g@node{#1}{\g@rectangletype}(#2,#3)[#4]}
        \g@extendlist\g@nodes{\g@drawsquarenode{#1}(#2,#3)[#4]}
}
%
% The actual drawing routine:
%
\def\g@drawsquarenode#1(#2,#3)[#4]{%
        \edef\g@size{\g@thenodesize{#1}}%
        {#4%
        \put(#2,#3){\expandafter\ps@rectangle\g@size}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of round nodes:
%
% Arguments:
%
% Nodename (a character sequence like abc)
% Position (x,y) = a pair of numbers
%_________________________________________________________________%%
%
\g@test{roundnode}
\def\roundnode#1(#2,#3){
        \@ifnextchar[{\g@roundnode{#1}(#2,#3)}{\g@roundnode{#1}(#2,#3)[]}
}
%
\def\g@roundnode#1(#2,#3)[#4]{
        \g@extendlist\g@nodeinfo{\g@node{#1}{\g@circletype}(#2,#3)[#4]}
        \g@extendlist\g@nodes{\g@drawroundnode{#1}(#2,#3)[#4]}
}
%
% The actual drawing routine:
%
\def\g@drawroundnode#1(#2,#3)[#4]{%
        \edef\g@size{\g@thenodesize{#1}}%
        {#4%%
        \put(#2,#3){\expandafter\ps@circle\g@size}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of rectangular nodes:
%
% Arguments:
%
% Nodename (a character sequence like abc)
% Size [width,height] (in multiples of \unitlength)
% Position (x,y) = a pair of numbers
%_________________________________________________________________%%
%
\g@test{rectnode}
\def\rectnode#1[#2,#3](#4,#5){
        \@ifnextchar[{\g@rectnode{#1}[#2,#3](#4,#5)}%
                {\g@rectnode{#1}[#2,#3](#4,#5)[]}
}
%
\def\g@rectnode#1[#2,#3](#4,#5)[#6]{
        \g@extendlist\g@nodeinfo{\g@noderect{#1}[#2,#3](#4,#5)}
        \g@extendlist\g@nodes{\g@drawrectnode{#1}[#6]}
}
%
% The actual drawing routine:
%
\def\g@drawrectnode#1[#2]{%
        \edef\g@size{\g@thenodesize{#1}}%
        \edef\g@coords{\g@nodecoords{#1}}%
        {#2%
        \expandafter\put\g@coords{\expandafter\ps@rectangle\g@size}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of text nodes (rectangular nodes whose dimension is
% determined by the given text):
%
% Arguments:
%
% Nodename (a character sequence like abc)
% Position (x,y) = a pair of numbers
% Text (=anything that may occur as a \put argument in a picture
%       environment, i.e., even lines, vectors, and so on.)
%_________________________________________________________________%%
%
\g@test{textnode}
\def\textnode#1(#2,#3)#4{
        \@ifnextchar[{\g@textnode{#1}(#2,#3){#4}}%
                {\g@textnode{#1}(#2,#3){#4}[]}
}
%
\def\g@textnode#1(#2,#3)#4[#5]{
        \autonodetext{#1}{#4}[#5]
        \g@extendlist\g@nodeinfo{\g@nodebytext{#1}(#2,#3){#4}[#5]}
        \g@extendlist\g@nodes{\g@drawrectnode{#1}%
                                        [\graphnodecolour{1}#5]}
}
%
%
%_________________________________________________________________%%
% Definition of an edge:
%
% Arguments:
%
% The two incident nodes
%_________________________________________________________________%%
%
\g@test{edge}
\def\edge#1#2{
        \@ifnextchar[{\g@edge{#1}{#2}}{\g@edge{#1}{#2}[]}
}
%
\def\g@edge#1#2[#3]{
        \g@extendlist\g@edges{\g@drawedge{#1}{#2}[#3]}
}
%
% The actual drawing routine:
%
\def\g@drawedge#1#2[#3]{%
        \g@testname{#1}\g@testname{#2}%
        \g@differentpositions{#1}{#2}{\edge{#1}{#2}}%
        \edef\g@firstcoords{\g@nodecoords{#1}}%
        \edef\g@secondcoords{\g@nodecoords{#2}}%
        \g@defcoorddiff{\g@diffcoords}{\g@firstcoords}{\g@secondcoords}%
        {#3%
        \expandafter\put\g@firstcoords{\expandafter\ps@line\g@diffcoords}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a directed edge:
%
% Arguments (same as for \edge):
%
% The two incident nodes (order indicates direction of the arrow)
%_________________________________________________________________%%
%
\g@test{diredge}
\def\diredge#1#2{
        \@ifnextchar[{\g@diredge{#1}{#2}}{\g@diredge{#1}{#2}[]}
}
%
\def\g@diredge#1#2[#3]{
        \g@extendlist\g@edges{\g@drawdiredge{#1}{#2}[#3]}
}
%
% The actual drawing routine:
%
\def\g@drawdiredge#1#2[#3]{%
        \g@testname{#1}\g@testname{#2}%
        \g@differentpositions{#1}{#2}{\diredge{#1}{#2}}%
        \edef\g@firstcoords{\g@nodecoords{#1}}%
        \edef\g@secondcoords{\g@nodecoords{#2}}%
        \g@defcoorddiff{\g@diffcoords}{\g@firstcoords}{\g@secondcoords}%
        %
        % Choose the right drawing procedure, according to the node's type:
        %
        \edef\g@type{\g@nodetype{#2}}%
        \ifnum\g@circletype=\g@type%
          \let\g@draw=\ps@arrowoncircle%
        \else%
          \let\g@draw=\ps@arrowonrectangle%
          \ifnum\g@rectangletype=\g@type%
          \else%
            \typeout{}%
            \typeout{Error in \string\g@drawdiredge: unrecognized node type}%
          \fi%
        \fi%
        %
        % and draw it:
        %
        \edef\g@diffcoordsandsize{\g@diffcoords\g@thenodesize{#2}}%
        {#3%
        \expandafter\put\g@firstcoords{\expandafter\g@draw\g@diffcoordsandsize}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a `bow' (a curved edge):
%
% Arguments:
%
% The two incident nodes
% The displacement factor of the midpoint relative to the distance.
%       of both nodes. A positive number means the bow extends 
%       to the left (if one looks in the direction of the edge).
%_________________________________________________________________%%
%
\g@test{bow}
\def\bow#1#2#3{
        \@ifnextchar[{\g@bow{#1}{#2}{#3}}{\g@bow{#1}{#2}{#3}[]}
}
%
\def\g@bow#1#2#3[#4]{
        \g@extendlist\g@edges{\g@drawbow{#1}{#2}{#3}[#4]}
}
%
% The actual drawing routine:
%
\def\g@drawbow#1#2#3[#4]{%
        \g@testname{#1}\g@testname{#2}%
        \g@differentpositions{#1}{#2}{\bow{#1}{#2}...}%
        \edef\g@firstcoords{\g@nodecoords{#1}}%
        \edef\g@secondcoords{\g@nodecoords{#2}}%
        \expandafter\g@bowcombine\g@secondcoords{#3}%
        {#4%
        \filledareasfalse%
        \put(0,0){\expandafter\ps@path\g@combineresult}%
        }%
}
%
% Macro used above to combine coordinates of nodes and displacement:
\def\g@bowcombine(#1,#2)#3{
        \edef\g@combineresult{\g@firstcoords{(#1,#2,#3)}}
}
%
%
%_________________________________________________________________%%
% Definition of a `directed bow' (a curved arrow):
%
% Arguments (same as for \bow):
%
% The two incident nodes
% The displacement factor of the midpoint relative to the distance.
%       of both nodes. A positive number means the bow extends 
%       to the left (if one looks in the direction of the edge).
%_________________________________________________________________%%
%
\g@test{dirbow}
\def\dirbow#1#2#3{
        \@ifnextchar[{\g@dirbow{#1}{#2}{#3}}{\g@dirbow{#1}{#2}{#3}[]}
}
%
\def\g@dirbow#1#2#3[#4]{
        \g@extendlist\g@edges{\g@drawdirbow{#1}{#2}{#3}[#4]}
}
%
% The actual drawing routine:
%
\def\g@drawdirbow#1#2#3[#4]{
        \g@testname{#1}\g@testname{#2}%
        \g@differentpositions{#1}{#2}{\dirbow{#1}{#2}...}%
        \edef\g@firstcoords{\g@nodecoords{#1}}%
        \edef\g@secondcoordsandsize{\g@nodecoords{#2}\g@thenodesize{#2}}%
        \expandafter\g@dirbowcombine\g@secondcoordsandsize{#3}%
        %
        % Choose the right drawing procedure, according to the node's type:
        %
        \edef\g@type{\g@nodetype{#2}}%
        \ifnum\g@circletype=\g@type%
          \let\g@draw=\ps@dirbowoncircle%
        \else%
          \let\g@draw=\ps@dirbowonrectangle%
          \ifnum\g@rectangletype=\g@type%
          \else%
            \typeout{}%
            \typeout{Error in \string\g@drawdirbow: unrecognized node type}%
          \fi%
        \fi%
        %
        % and draw it:
        %
        {#4%
        \filledareasfalse%
        \put(0,0){\expandafter\g@draw\g@combineresult}%
        }%
}
%
% Macro used above to combine coordinates of nodes and displacement:
\def\g@dirbowcombine(#1,#2)[#3]#4{
        \edef\g@combineresult{\g@firstcoords(#1,#2,#4)[#3]}
}
%
%
%_________________________________________________________________%%
% Definition of a loop. There're two ways to provide this macro
% with the necessary arguments. Here's the
% first:
%
% Arguments:
%
% Node that carries the loop
% Two relative coordinates (x1,y1) (x2,y2) indicating the lines from
%       the incident node to (x1,y1) and (x2,y2) that form the loop
%       together with a curve connecting (x1,y1) and (x2,y2).
%_________________________________________________________________%%
%
\g@test{loopedge}
\def\loopedge#1{
        \@ifnextchar({\g@loopedgeA{#1}}{\g@loopedgeB{#1}}
}
%
\def\g@loopedgeA#1(#2,#3)(#4,#5){
        \@ifnextchar[{\g@loopedgeAa{#1}(#2,#3)(#4,#5)}%
                        {\g@loopedgeAa{#1}(#2,#3)(#4,#5)[]}
}
%
\def\g@loopedgeAa#1(#2,#3)(#4,#5)[#6]{
        \g@extendlist\g@edges{\g@drawloopedgeA{#1}(#2,#3)(#4,#5)[#6]}
}
%
% The actual drawing routine:
%
\def\g@drawloopedgeA#1(#2,#3)(#4,#5)[#6]{%
        \g@testname{#1}%
        \edef\g@coords{\g@nodecoords{#1}}%
        {#6%
        \expandafter\put\g@coords{%%
          \ps@loopA(#2,#3)(#4,#5)}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a loop - the second form:
%
% Arguments:
%
% Node that carries the loop
% Angle the two lines defining the loop build
% Coordinates (x,y) that give the axis along which the loop is
% to be drawn and its length (ie, the length of the two lines 
% defining the loop).
%_________________________________________________________________%%
%
\def\g@loopedgeB#1#2(#3,#4){
        \@ifnextchar[{\g@loopedgeBa{#1}{#2}(#3,#4)}%
                        {\g@loopedgeBa{#1}{#2}(#3,#4)[]}
}
%
\def\g@loopedgeBa#1#2(#3,#4)[#5]{
        \g@extendlist\g@edges{\g@drawloopedgeB{#1}{#2}(#3,#4)[#5]}
}
%
% The actual drawing routine:
%
\def\g@drawloopedgeB#1#2(#3,#4)[#5]{%
        \g@testname{#1}%
        \edef\g@coords{\g@nodecoords{#1}}%
        {#5%
        \expandafter\put\g@coords{%%
          \ps@loopB{#2}(#3,#4)}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a directed loop. There're two ways to provide
% this macro with the necessary arguments. Here's the first:
%
% Arguments:
%
% Node that carries the loop
% Two relative coordinates (x1,y1) (x2,y2) indicating the lines from
%       the incident node to (x1,y1) and (x2,y2) that form the loop
%       together with a curve connecting (x1,y1) and (x2,y2).
%_________________________________________________________________%%
%
\g@test{dirloopedge}
\def\dirloopedge#1{
        \@ifnextchar({\g@dirloopedgeA{#1}}{\g@dirloopedgeB{#1}}
}
%
\def\g@dirloopedgeA#1(#2,#3)(#4,#5){
        \@ifnextchar[{\g@dirloopedgeAa{#1}(#2,#3)(#4,#5)}%
                        {\g@dirloopedgeAa{#1}(#2,#3)(#4,#5)[]}
}
%
\def\g@dirloopedgeAa#1(#2,#3)(#4,#5)[#6]{
        \g@extendlist\g@edges{\g@drawdirloopedgeA{#1}(#2,#3)(#4,#5)[#6]}
}
%
% The actual drawing routine:
%
\def\g@drawdirloopedgeA#1(#2,#3)(#4,#5)[#6]{%
        \g@testname{#1}%
        \edef\g@coords{\g@nodecoords{#1}}%
        %
        % Choose the drawing procedure for the arrow according
        % to the node's type:
        %
        \edef\g@type{\g@nodetype{#1}}%
        \ifnum\g@circletype=\g@type%
          \let\g@draw=\ps@looparrowoncircleA%
        \else%
          \let\g@draw=\ps@looparrowonrectangleA%
          \ifnum\g@rectangletype=\g@type%
          \else%
            \typeout{}%
            \typeout{Error in \string\g@drawdirloopedge: unrecognized node type}%%
          \fi%
        \fi%
        \edef\g@args{(#2,#3)(#4,#5)\g@thenodesize{#1}}%
        %
        % and draw it:
        %
        {#6%
        \expandafter\put\g@coords{\expandafter\g@draw\g@args}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a directed loop - the second form:
%
% Arguments:
%
% Node that carries the loop
% Angle the two lines defining the loop build
% Coordinates (x,y) that give the axis along which the loop is
% to be drawn and its length (ie, the length of the two lines 
% defining the loop).
%_________________________________________________________________%%
%
\def\g@dirloopedgeB#1#2(#3,#4){
        \@ifnextchar[{\g@dirloopedgeBa{#1}{#2}(#3,#4)}%
                        {\g@dirloopedgeBa{#1}{#2}(#3,#4)[]}
}
%
\def\g@dirloopedgeBa#1#2(#3,#4)[#5]{
        \g@extendlist\g@edges{\g@drawdirloopedgeB{#1}{#2}(#3,#4)[#5]}
}
%
% The actual drawing routine:
%
\def\g@drawdirloopedgeB#1#2(#3,#4)[#5]{%
        \g@testname{#1}%
        \edef\g@coords{\g@nodecoords{#1}}%
        %
        % Choose the drawing procedure for the arrow according
        % to the node's type:
        %
        \edef\g@type{\g@nodetype{#1}}%
        \ifnum\g@circletype=\g@type%
          \let\g@draw=\ps@looparrowoncircleB%
        \else%
          \let\g@draw=\ps@looparrowonrectangleB%
          \ifnum\g@rectangletype=\g@type%
          \else%
            \typeout{}%
            \typeout{Error in \string\g@drawdirloopedge: unrecognized node type}%%
          \fi%
        \fi%
        \edef\g@args{{#2}(#3,#4)\g@thenodesize{#1}}%
        %
        % and draw it:
        %
        {#5%
        \expandafter\put\g@coords{\expandafter\g@draw\g@args}%
        }%
}
%
%
%_________________________________________________________________%%
% Automatic positioning of a node's text
% (This one sets \opaquetextfalse if it's not enforced by the optional
% parameter!):
%
% Arguments:
%
% Node
% Optional (surrounded by []): n, s, e, w, ne, nw, se, sw (for north,
%       south, east, west, ...) indicating the position of the text
%       with respect to the node. If omitted, the text is centered
%       inside the node.
% Text (=anything that may occur as a \put argument in a picture
%       environment, i.e., even lines, vectors, and so on.)
%_________________________________________________________________%%
%
\g@test{autonodetext}
\def\autonodetext#1{
  \@ifnextchar[{\g@autonodetext{#1}}{\g@autonodetext{#1}[]}
}
%
\def\g@autonodetext#1[#2]#3{
  \@ifnextchar[{\g@autonodetextopt{#1}{#3}[#2]}%
        {\g@autonodetextopt{#1}{#3}[#2][]}
}
%
\def\g@rootofahalf{.70710678}% square root of 0.5
%
\def\g@autonodetextopt#1#2[#3][#4]{
  \def\g@doit##1##2##3;{
    \def\g@xdisplace{0}\def\g@ydisplace{0}\def\g@torb{,0]}\def\g@lorr{[0}
    \def\g@xdisplacec{0}\def\g@ydisplacec{0}
    \if##2.
      \if##1s\def\g@ydisplace{-1}\def\g@torb{,-1]}\else
      \if##1n\def\g@ydisplace{1}\def\g@torb{,1]}\else
      \if##1e\def\g@xdisplace{1}\def\g@lorr{[1}\else
      \if##1w\def\g@xdisplace{-1}\def\g@lorr{[-1}\fi\fi\fi\fi
      \edef\g@xdisplacec{\g@xdisplace}\edef\g@ydisplacec{\g@ydisplace}
    \else
      \if##1s\def\g@ydisplace{-1}\def\g@torb{,-1]}
        \def\g@ydisplacec{-\g@rootofahalf}\else
      \if##1n\def\g@ydisplace{1}\def\g@torb{,1]}
        \def\g@ydisplacec{\g@rootofahalf}\else
      \if##1e\def\g@xdisplace{1}\def\g@lorr{[1}
        \def\g@xdisplacec{\g@rootofahalf}\else
      \if##1w\def\g@xdisplace{-1}\def\g@lorr{[-1}
        \def\g@xdisplacec{-\g@rootofahalf}\fi\fi\fi\fi
      \if##2e\def\g@xdisplace{1}\def\g@lorr{[1}
        \def\g@xdisplacec{\g@rootofahalf}\else
      \if##2w\def\g@xdisplace{-1}\def\g@lorr{[-1}
        \def\g@xdisplacec{-\g@rootofahalf}
      \fi\fi
    \fi
    \edef\g@values{%
      {(\g@xdisplacec,\g@ydisplacec)}{\g@lorr\g@torb}{%
        (\g@xdisplace,\g@ydisplace)}%
    }
    \expandafter\g@extendtextsauto\g@values{#1}{#2}[#4]}
  \g@doit#3...;}
%
%
\def\g@extendtextsauto#1#2#3#4#5[#6]{
        \g@extendlist\g@texts{\g@putautotext{#1}{#2}{#3}{#4}{#5}[#6]}
}
%
% The actual drawing routine:
%
\def\g@putautotext#1#2#3#4#5[#6]{%
        \g@testname{#4}%
        \edef\g@coords{\g@nodecoords{#4}}%
        \edef\g@type{\g@nodetype{#4}}%
        \edef\g@size{\g@thenodesize{#4}}%
        \ifnum\g@circletype=\g@type%
          \def\g@draw{\g@xyput#1}%
          \expandafter\g@getcirclexy\g@size%
        \else%
          \def\g@draw{\g@xyput#3}%
          \expandafter\g@getrectanglexy\g@size%
          \ifnum\g@rectangletype=\g@type%
          \else%
            \typeout{}%
            \typeout{Error in \string\putautotext: unrecognized node type}%
          \fi%
        \fi%
        \expandafter\put\g@coords{%
          \opaquetextfalse #6%
          \g@textsize{#5}%
          \g@xunitlength=\g@autodistance\g@xunitlength\divide\g@xunitlength by 2%
          \g@yunitlength=\g@autodistance\g@yunitlength\divide\g@yunitlength by 2%
          \ifopaquetext%
            \g@draw{\expandafter\g@makeautotext\g@thetextsize%
                #2{\expandafter\ps@deletebox\g@thetextsize}}%
          \fi%
          \g@draw{\expandafter\g@makeautotext\g@thetextsize%
                #2{\makebox(0,0){#5}}}%
        }%
}%
%
\def\g@getcirclexy[#1]{
        \g@xunitlength=#1\unitlength\relax
        \g@yunitlength=\g@xunitlength\relax
}
%
\def\g@getrectanglexy[#1,#2]{
        \g@xunitlength=#1\unitlength\relax
        \g@yunitlength=#2\unitlength\relax
}
%
\newcount\g@xpos
\newcount\g@ypos
\def\g@makeautotext(#1,#2)[#3,#4]#5{%
        \g@oldunitlength=\unitlength%
        \g@xpos=#1\divide\g@xpos by 2\multiply\g@xpos by #3\relax%
        \g@ypos=#2\divide\g@ypos by 2\multiply\g@ypos by #4\relax%
        \unitlength=1sp%
        \edef\g@positions{(\number\g@xpos,\number\g@ypos)}%
        \expandafter\put\g@positions{\unitlength=\g@oldunitlength{#5}}%
}%
%
%
%_________________________________________________________________%%
% Definition of a node's text:
%
% Arguments:
%
% Node
% Relative coordinates of the text (optional).
%       Text is centered horizontally and vertically at this position.
%       (Use a \makebox(0,0)[...]{Text} construction to disable the
%       centering if necessary.)
%       Omitting the optinal argument means the same as (0,0).
% Text (=anything that may occur as a \put argument in a picture
%       environment, i.e., even lines, vectors, and so on.)
%_________________________________________________________________%%
%
\g@test{nodetext}
\def\nodetext#1{
        \@ifnextchar({\g@nodetext{#1}}{\g@nodetext{#1}(0,0)}
}
\def\g@nodetext#1(#2,#3)#4{
        \@ifnextchar[{\g@nodetextb{#1}(#2,#3){#4}}%
                        {\g@nodetextb{#1}(#2,#3){#4}[]}
}
%
\def\g@nodetextb#1(#2,#3)#4[#5]{
        \g@extendlist\g@texts{\g@putnodetext{#1}(#2,#3){#4}[#5]}
}
%
% The actual drawing routine:
%
\def\g@putnodetext#1(#2,#3)#4[#5]{%
        \g@testname{#1}%
        \edef\g@coords{\g@nodecoords{#1}}%
        \expandafter\put\g@coords{%
          #5%
          \ifopaquetext%
            \g@textsize{#4}%
            \put(#2,#3){\expandafter\ps@deletebox\g@thetextsize}%
          \fi%
          \put(#2,#3){\makebox(0,0){#4}}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of an edge's text (for straight edges only):
%
% Arguments:
%
% Both nodes incident with the edge in question
% Text (=anything that may occur as a \put argument in a picture
%       environment, i.e., even lines, vectors, and so on.)
%_________________________________________________________________%%
%
\g@test{edgetext}
\def\edgetext#1#2#3{
        \@ifnextchar[{\g@edgetext{#1}{#2}{#3}}%
                        {\g@edgetext{#1}{#2}{#3}[]}
}
%
\def\g@edgetext#1#2#3[#4]{
        \g@extendlist\g@texts{\g@putedgetext{#1}{#2}{#3}[#4]}
}
%
% The actual drawing routine:
%
\def\g@putedgetext#1#2#3[#4]{%
        \g@testname{#1}\g@testname{#2}%
        \g@differentpositions{#1}{#2}{\edgetext{#1}{#2}...}%
        \edef\g@firstcoords{\g@nodecoords{#1}}%
        \edef\g@secondcoords{\g@nodecoords{#2}}%
        {%
          #4%
          \g@textsize{#3}%
          \g@oldunitlength=\unitlength%
          \divide\unitlength by 2%
          \expandafter\put\g@firstcoords{%
            \ifopaquetext%
              \expandafter\put\g@secondcoords{%
                \expandafter\ps@deletebox\g@thetextsize%
              }%
            \fi%
            \expandafter\put\g@secondcoords{%
              \unitlength=\g@oldunitlength%
              \makebox(0,0){#3}%
            }%
          }%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a bow's text:
%
% Arguments:
%
% Both nodes and displacement factor defining the bow in question
% Text (=anything that may occur as a \put argument in a picture
%       environment, i.e., even lines, vectors, and so on.)
%_________________________________________________________________%%
%
\g@test{bowtext}
\def\bowtext#1#2#3#4{
        \@ifnextchar[{\g@bowtext{#1}{#2}{#3}{#4}}%
                        {\g@bowtext{#1}{#2}{#3}{#4}[]}
}
%
\def\g@bowtext#1#2#3#4[#5]{
        \g@extendlist\g@texts{\g@putbowtext{#1}{#2}{#3}{#4}[#5]}
}
%
% The actual drawing routine:
%
\newdimen\g@x
\newdimen\g@y
\newdimen\g@aux
\def\g@putbowtext#1#2#3#4[#5]{%
        \g@testname{#1}\g@testname{#2}%
        \g@differentpositions{#1}{#2}{\bowtext{#1}{#2}...}%
        \def\g@doit(##1,##2)(##3,##4){%
          {#5%
          \g@textsize{#4}%
          \g@oldunitlength=\unitlength%
          \unitlength=.5\unitlength%
          %
          % Compute the difference of coordinates:
          %
          \g@x=##3\g@oldunitlength\g@aux=##1\g@oldunitlength%
          \advance\g@x by -\g@aux\g@x=#3\g@x%
          \g@y=##4\g@oldunitlength\g@aux=##2\g@oldunitlength%
          \advance\g@y by -\g@aux\g@y=#3\g@y%
          \g@y=-\g@y%
          \edef\g@thirdcoords{(\number\g@y,\number\g@x)}%
          \put(##1,##2){%
            \ifopaquetext%
              \put(##3,##4){%
                \unitlength=1sp%
                \expandafter\put\g@thirdcoords{%
                  \expandafter\ps@deletebox\g@thetextsize%
                }%
              }%
            \fi%
            \put(##3,##4){%
              \unitlength=1sp%
              \expandafter\put\g@thirdcoords{%
                \unitlength=\g@oldunitlength%
                \makebox(0,0){#4}%
              }%
            }%
          }}%
        }%
        \edef\g@firstcoords{\g@nodecoords{#1}}%
        \edef\g@secondcoords{\g@nodecoords{#2}}%
        %
        % Expand both arguments before executing \g@doit:
        %
        \expandafter\expandafter\expandafter%
                \g@doit\expandafter\g@firstcoords\g@secondcoords%
}
%
%
%_________________________________________________________________%%
% Definition of free text:
%
% Arguments:
%
% Absolute coordinates of the text. (Text is centered horizontally
%       and vertically at this position. Use a
%       \makebox(0,0)[...]{Text} construction to disable the
%       centering if necessary.)
% Text (=anything that may occur as a \put argument in a picture
%       environment, i.e., even lines, vectors, and so on.)
%_________________________________________________________________%%
%
\g@test{freetext}
\def\freetext(#1,#2)#3{
        \@ifnextchar[{\g@freetext(#1,#2){#3}}%
                        {\g@freetext(#1,#2){#3}[]}
}
%
\def\g@freetext(#1,#2)#3[#4]{
        \g@extendlist\g@texts{\g@putfreetext(#1,#2){#3}[#4]}
}
%
% The actual drawing routine:
%
\def\g@putfreetext(#1,#2)#3[#4]{%
        {#4%
        \ifopaquetext%
          \g@textsize{#3}%
          \put(#1,#2){\expandafter\ps@deletebox\g@thetextsize}%
        \fi%
        \put(#1,#2){\makebox(0,0){#3}}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a (perhaps filled) area:
%
% Arguments:
%
% Absolute coordinates of the starting point
% Sequence of pairs (x_i,y_i) or triples (x_i,y_i,d_i) where the
%       (x_i,y_i) are absolute coordinates of the next segment's
%       end point and d_i is the displacement factor of the midpoint
%       relative to the length of the segment. A positive number
%       means the segment extends to the left.
%_________________________________________________________________%%
%
\g@test{area}
\def\area(#1,#2)#3{
        \@ifnextchar[{\g@area(#1,#2){#3}}%
                        {\g@area(#1,#2){#3}[]}
}
%
\def\g@area(#1,#2)#3[#4]{
        \g@extendlist\g@specialeffects{\g@putarea(#1,#2){#3}[#4]}
}
%
% The actual drawing routine:
%
\def\g@putarea(#1,#2)#3[#4]{%
        {#4%
        \put(0,0){\ps@path(#1,#2){#3}}%
        }%
}
%
% For reasons of compatibility with older versions:
\g@test{filledarea}\def\filledarea{\area}
%
%
%_________________________________________________________________%%
% Definition of a (perhaps filled) Bezier curve:
%
% Arguments:
%
% Normal distance of control points from points of the curve,
%       in multiples of the segment length.
% Sequence of triples (x_i,y_i,alpha_i), and and optional
%       [factora_i,factorb_i]) after each of the triples:
%       (x_i,y_i) is a point on the curve, alpha_i is the angle
%       between the x-axis and the line through (x_i,y_i) and the
%       next control point (the previous control point lies opposite),
%       and factora_i (factorb_i) is overwrites the first argument
%       for the two control points between two points.
%_________________________________________________________________%%
%
\g@test{curve}
\def\curve#1#2{
        \@ifnextchar[{\g@curve{#1}{#2}}%
                        {\g@curve{#1}{#2}[]}
}
%
\def\g@curve#1#2[#3]{
        \g@extendlist\g@specialeffects{\g@putcurve{#1}{#2}[#3]}
}
%
% The actual drawing routine:
%
\def\g@putcurve#1#2[#3]{%
        {#3%
        \put(0,0){\ps@curve{#1}{#2}}%
        }%
}
%
%
%_________________________________________________________________%%
% Definition of a (perhaps filled) Bezier ``bubble'':
%
% Arguments:
%
% Normal distance (in multiples of unitlength) of control points
%       in multiples of segment length.
% Sequence of points (x_i,y_i).
%_________________________________________________________________%%
%
\g@test{bubble}
\def\bubble#1#2{
        \@ifnextchar[{\g@bubble{#1}{#2}}%
                        {\g@bubble{#1}{#2}[]}
}
%
\def\g@bubble#1#2[#3]{
        \g@extendlist\g@specialeffects{\g@putbubble{#1}{#2}[#3]}
}
%
% The actual drawing routine:
%
\def\g@putbubble#1#2[#3]{%
        {#3%
        \put(0,0){\ps@bubble{#1}{#2}}%
        }%
}
%
%
%
%
%
%_________________________________________________________________%%
%_________________________________________________________________%%
%_________________________________________________________________%%
% The rest consists of auxiliary macros used above:
%_________________________________________________________________%%
%_________________________________________________________________%%
%_________________________________________________________________%%
%
%
%
%_________________________________________________________________%%
% Globally extend a list by another item.
%
% Replaces the definition of the macro #1 by the expansion of #1
% immediately followed by #2.
%_________________________________________________________________%%
%
\def\g@extendlist#1#2{
        \expandafter\def\expandafter#1\expandafter{#1#2}
}
%
%
%_________________________________________________________________%%
% Give the different attributes of a node.
%_________________________________________________________________%%
%
\def\g@nodecoords#1{%
        \csname g@xy@#1\endcsname%
}
\def\g@nodetype#1{%
        \csname g@type@#1\endcsname%
}
\def\g@thenodesize#1{%
        \csname g@size@#1\endcsname%
}
\def\g@testname#1{%
        \@ifundefined{g@name@#1}{%
                \typeout{}%
                \typeout{! Graph package error: node #1 undefined!}%
                \typeout{}%
                \errmessage{}%
        }{}%
}
%
%
%_________________________________________________________________%%
% Give the difference between coordinate pairs the second and
% third argument expand to and define the first as the result.
%_________________________________________________________________%%
%
\def\g@defcoorddiff#1#2#3{
        \edef#1{% Expand both arguments before expanding \g@coorddiff:
        \expandafter\expandafter\expandafter\g@coorddiff\expandafter#2#3}
}
%
\def\g@coorddiff(#1,#2)(#3,#4){(#3 #1 sub, #4 #2 sub)
}
%
%
%_________________________________________________________________%%
% Find out the size of a box and add \g@eboxes.
%_________________________________________________________________%%
%
\newdimen\g@heightplusdepth
\newdimen\g@width
\def\g@textsize#1{
        \setbox0=\hbox{#1}
        \g@heightplusdepth=\ht0
        \advance\g@heightplusdepth by\dp0
        \advance\g@heightplusdepth by\g@eboxes\unitlength
        \g@width=\wd0
        \advance\g@width by\g@eboxes\unitlength
        \edef\g@thetextsize{%
          (\number\g@width,\number\g@heightplusdepth)%
        }
}
%
%
%_________________________________________________________________%%
% Save the information about a node in appropriate macros
% (one macro to treat round and square nodes, one for
% rectangular nodes, and one for text nodes):
%_________________________________________________________________%%
%
\def\g@node#1#2(#3,#4)[#5]{
        \g@nodedef{g@name@#1}{}
        {
          #5
          \xdef\g@auxnodesize{\g@nsize}
        }
        \g@nodedef{g@xy@#1}{(#3,#4)}
        \g@nodedef{g@type@#1}{#2}
        \ifx\g@rectangletype#2
          \g@nodedef{g@size@#1}{[\g@auxnodesize,\g@auxnodesize]}
        \else
          \g@nodedef{g@size@#1}{[\g@auxnodesize]}
        \fi
}
%
\def\g@noderect#1[#2,#3](#4,#5){
        \g@nodedef{g@name@#1}{}
        \g@nodedef{g@xy@#1}{(#4,#5)}
        \g@nodedef{g@type@#1}{\g@rectangletype}
        \g@nodedef{g@size@#1}{[#2,#3]}
}
%
\def\g@nodebytext#1(#2,#3)#4[#5]{
        \g@nodedef{g@name@#1}{}
        \g@nodedef{g@xy@#1}{(#2,#3)}
        \g@nodedef{g@type@#1}{\g@rectangletype}
        {#5
          \g@textsize{#4}
          \expandafter\g@findsize\g@thetextsize
        }
        \g@nodedef{g@size@#1}{\g@auxtextsize}
}
%
\def\g@nodedef#1#2{\expandafter\edef\csname #1\endcsname{#2}}
%
%
%
%_________________________________________________________________%%
% Compare the coordinates of nodes and give an error message if they
% coincide. (Used to prevent the definition of edges of length 0.)
%_________________________________________________________________%%
%
%
\def\g@differentpositions#1#2#3{%
        \edef\g@firstname{#1}%
        \edef\g@secondname{#2}%
        \ifx\g@firstname\g@secondname%
          \typeout{}%
          \typeout{! Graph package error: Node #1 used twice
          in \string#3.}%
          \typeout{}%
          \errmessage{}
        \else
          \edef\g@firstposition{\g@nodecoords{#1}}%
          \edef\g@secondposition{\g@nodecoords{#2}}%
          \ifx\g@firstposition\g@secondposition%
            \typeout{}%
            \typeout{! Graph package error: Coordinates of nodes
            #1 and #2 in}%
            \typeout{\string#3 coincide.}%
            \typeout{}%
            \errmessage{}           
          \fi%
        \fi%
}
%
%
%
%_________________________________________________________________%%
% Nasty procedure to compute the necessary size of the node. We need
% something that computes
%            textdimension / \unitlength + 2 * \g@lwidth
% with high precision. So we can't simply use the \divide macro of
% TeX (yielding an integer value), but must explicitely construct a
% number showing some (I chose three) digits after the period.
% (I don't know whether there's a more elegant way of doing this.
% Sorry to anybody who might be bothered.)
%_________________________________________________________________%%
%
%
\newcount\g@xsizeA
\newcount\g@xsizeB
\newcount\g@ysizeA
\newcount\g@ysizeB
\newcount\g@help
\newdimen\g@helpB
\def\g@findsize(#1,#2){
        \g@xsizeA=#1\relax
        \g@helpB=\g@lwidth\unitlength\multiply\g@helpB by 2\relax
        \advance\g@xsizeA by \g@helpB\relax
        \g@xsizeB=\g@xsizeA
        \divide\g@xsizeA by\unitlength\relax
        \g@help=\unitlength\multiply\g@help by -\g@xsizeA\relax
        \advance\g@xsizeB by \g@help\relax
        \g@help=\unitlength\advance\g@help by 999\divide\g@help by 1000
                                                        \multiply\g@help by 1000
        \advance\g@xsizeB by \g@help\relax
        \divide\g@help by 1000
        \divide\g@xsizeB by \g@help
        %
        \g@ysizeA=#2\relax
        \advance\g@ysizeA by \g@helpB\relax
        \g@ysizeB=\g@ysizeA
        \divide\g@ysizeA by\unitlength\relax
        \g@help=\unitlength\multiply\g@help by -\g@ysizeA\relax
        \advance\g@ysizeB by \g@help\relax
        \g@help=\unitlength\advance\g@help by 999\divide\g@help by 1000
                                                        \multiply\g@help by 1000
        \advance\g@ysizeB by \g@help\relax
        \divide\g@help by 1000
        \divide\g@ysizeB by \g@help
        \xdef\g@auxtextsize{%
          [\expandafter\g@mkpoint\number\g@xsizeB;{\number\g@xsizeA},%
           \expandafter\g@mkpoint\number\g@ysizeB;{\number\g@ysizeA}]}
}
%
\def\g@mkpoint#1#2;#3{
        #3.#2
}
%
%
%_________________________________________________________________%%
% \put with separated x- and y-\unitlengths
% (modified definition from LaTeX):
%_________________________________________________________________%%
%
\newdimen\g@xunitlength\g@xunitlength=\unitlength
\newdimen\g@yunitlength\g@yunitlength=\unitlength
\long\def\g@xyput(#1,#2)#3{\@killglue\raise#2\g@yunitlength\hbox to\z@{\kern
#1\g@xunitlength #3\hss}\ignorespaces}