% treedef.tex
%
% These definitions for tree macros are taken from "Trees in TeX",
% by David Eppstein, as published in TUGboat 6#1, March 1985.
% David Eppstein's address (as of 15 June 1988) is
% Computer Science Department
% Columbia University
% New York, NY 10027
% Eppstein@cs.Columbia.edu
%
% Tree -- a macro to make aligned (horizontal) trees in TeX
%
% Input is of the form
% \tree
% item
% \subtree
% \leaf{item}
% .
% .
% .
% \endsubtree
% \subtree
% .
% .
% .
% \endsubtree
% \endsubtree
% \endtree
%
% Nesting is to any level. \leaf is defined as a subtree of one item:
% \def\leaf#1{\subtree#1\endsubtree}.
%
% A structure:
% \subtree
% item_part1
% item_part2
% .
% .
% .
%
% will print item_part2 directly below item_part1 as a single item
% as if they were in a \box.
%
% The macro is a 3-pass macro. On the first pass it sets up a data
% structure from the \subtree ... \endsubtree definitions. On the second pass
% it recursively calculates the width of each level of the tree. On the third
% pass it sets up the boxes, glue and rules.
%
% By David Eppstein, TUGboat, vol. 6 (1985), no. 1, pp. 31--35.
% Transcribed by Margaret Kromer (peg), Feb., 1986.
%
% Pass 1
% At the end of pass 1, the tree is coded as a nested collection of \hboxes
% and \vboxes.
\newbox\treebox\newcount\treeboxcnt
\def\tree{\message{Begin tree}\treeboxcnt=1\global\setbox\treebox=\boxtree}
\def\subtree{\ettext \advance\treeboxcnt by 1 \boxtree}
\def\leaf#1{\subtree#1\endsubtree}
\def\endsubtree{\ettext \egroup \advance\treeboxcnt-1{}%
\ifnum\treeboxcnt=-1 \treeerrora\fi}
\def\endtree{\endsubtree \ifnum\treeboxcnt>0 \treeerrorb\fi%
\settreesizes \typesettree \message{-- end tree}}
% Error messages for unbalanced tree
\def\treeerrora{\errhelp=\treeerrorahelp%
\errmessage{Unbalanced tree -- too many endsubtrees}}
\newhelp\treeerrorahelp{There are more subtrees closed than opened}
\def\treeerrorb{\errhelp=\treeerrorbhelp%
\errmessage{Unbalanced tree -- not enough endsubtrees}}
\newhelp\treeerrorbhelp{Not all the subtrees of the tree are closed.
If you continue, you'll get some mysterious secondary errors.}
% Set up \vbox containing root of tree
\newif\iftreetext\treetextfalse % Whether still aligning text
\def\boxtree{\hbox\bgroup % Start outer box of tree or subtree
\baselineskip 2.5ex % Narrow line spacing slightly
\tabskip 0pt % No spurious glue in alignment
\vbox\bgroup % Start inner text \vbox
\treetexttrue % Remember for \ettext
\let\par\crcr \obeylines % New line breaks without explicit \cr
\halign\bgroup##\hfil\cr} % Start alignment with simple template
\def\ettext{\iftreetext % Are we still in inner text \vbox?
\crcr\egroup \egroup \fi} % Yes, end alignment and box
% Pass 2
% Recursively calculate widths of tree with \setsizes; keep results in
% \treesizes; \treewidth contains total width calculated so far. \treeworkbox
% is workspace containing subtree being sized.
\newbox\treeworkbox
\def\cons#1#2{\edef#2{\xmark #1#2}} % Add something to start of list
\def\car#1{\expandafter\docar#1\docar} % Take first element of list
\def\docar\xmark#1\xmark#2\docar{#1} % ..by ignoring rest in expansion
\def\cdr#1{\expandafter\docdr#1\docdr#1}% Similarly, drop first element
\def\docdr\xmark#1\xmark#2\docdr#3{\def#3{\xmark #2}}
\def\xmark{\noexpand\xmark} % List separator expands to self
\def\nil{\xmark} % Empty list is just separator
\def\settreesizes{\setbox\treeworkbox=\copy\treebox%
\global\let\treesizes\nil \setsizes}
\newdimen\treewidth % Width of this part of the tree
\def\setsizes{\setbox\treeworkbox=\hbox\bgroup% Get a horiz list as a workspace
\unhbox\treeworkbox\unskip % Take tree, unpack it into horiz list
\inittreewidth % Get old width at this level
\sizesubtrees % Recurse through all subtrees
\sizelevel % Now set width from remaining \vbox
\egroup} % All done, finish our \hbox
\def\inittreewidth{\ifx\treesizes\nil % If this is the first at this level
\treewidth=0pt % ..then we have no previous max width
\else \treewidth=\car\treesizes % Otherwise take old max level width
\global\cdr\treesizes % ..and advance level width storage
\fi} % ..in preparation for next level.
\def\sizesubtrees{\loop % For each box in horiz list (subtree)
\setbox\treeworkbox=\lastbox \unskip % ..pull it off list and flush glue
\ifhbox\treeworkbox \setsizes % If hbox, it's a subtree - recurse
\repeat} % ..and loop; end loop on tree text
\def\sizelevel{%
\ifdim\treewidth<\wd\treeworkbox % If greater than previous maximum
\treewidth=\wd\treeworkbox \fi % Then set max to new high
\global\cons{\the\treewidth}\treesizes}% In either case, put back on list
% Pass 3
% Recursively typeset tree with \maketree by adding an \hbox containing
% a subtree (in \treebox) to the horizontal list.
\newdimen\treeheight % Height of this part of the tree
\newif\ifleaf % Tree has no subtrees (is a leaf)
\newif\ifbotsub % Bottom subtree of parent
\newif\iftopsub % Top subtree of parent
\def\typesettree{\medskip\maketree\medskip} % Make whole tree
\def\maketree{\hbox{\treewidth=\car\treesizes % Get width at this level
\cdr\treesizes % Set up width list for recursion
\makesubtreebox\unskip % Set \treebox to text, make subtrees
\ifleaf \makeleaf % No subtrees, add glue
\else \makeparent \fi}} % Have subtrees, stick them at right
{\catcode`@=11 % Be able to use \voidb@x
\gdef\makesubtreebox{\unhbox\treebox % Open up tree or subtree
\unskip\global\setbox\treebox\lastbox % Pick up very last box
\ifvbox\treebox % If we're already at the \vbox
\global\leaftrue \let\next\relax % ..then this is a leaf
\else \botsubtrue % Otherwise, we have subtrees
\setbox\treeworkbox\box\voidb@x % Init stack of processed subs
\botsubtrue \let\next\makesubtree % ..and call \maketree on them
\fi \next}} % Finish up for whichever it was
\def\makesubtree{\setbox1\maketree % Call \maketree on this subtree
\unskip\global\setbox\treebox\lastbox % Pick up box before it
\treeheight=\ht1 % Get height of subtree we made
\advance\treeheight 2ex % Add some room around the edges
\ifhbox\treebox \topsubfalse % If picked up box is a \vbox,
\else \topsubtrue \fi % ..this is the top, otherwise not
\addsubtreebox % Stack subtree with the rest
\iftopsub \global\leaffalse % If top, remember not a leaf
\let\next\relax \else % ..(after recursion), set return
\botsubfalse \let\next\makesubtree % Otherwise, we have more subtrees
\fi \next} % Do tail recursion or return
\def\addsubtreebox{\setbox\treeworkbox=\vbox{\subtreebox\unvbox\treeworkbox}}
\def\subtreebox{\hbox\bgroup % Start \hbox of tree and lines
\vbox to \treeheight\bgroup % Start \vbox for vertical rules
\ifbotsub \iftopsub \vfil % If both bottom and top subtree
\hrule width 0.4pt % ..vertical rule is just a dot
\else \treehalfrule \fi \vfil % Bottom gets half-height rule
\else \iftopsub \vfil \treehalfrule % Top gets half-height the other way
\else \hrule width 0.4pt height \treeheight \fi\fi % Middle, full height
\egroup % Finish vertical rule \vbox
\treectrbox{\hrule width 1em}\hskip 0.2em\treectrbox{\box1}\egroup}
\def\treectrbox#1{\vbox to \treeheight{\vfil #1\vfil}}
\def\treehalfrule{\dimen\treeworkbox=\treeheight % Get total height
\divide\dimen\treeworkbox 2%
\advance\dimen\treeworkbox 0.2pt % Divide by two, add half horiz height
\hrule width 0.4pt height \dimen\treeworkbox}% Make a vertical rule that high
\def\makeleaf{\box\treebox} % Add leaf box to horiz list
\def\makeparent{\ifdim\ht\treebox>%
\ht\treeworkbox % If text is higher than subtrees
\treeheight=\ht\treebox % ..use that height
\else \treeheight=\ht\treeworkbox \fi % Otherwise use height of subtrees
\advance\treewidth-\wd\treebox % Take remainder of level width
\advance\treewidth 1em % ..after accounting for text and glue
\treectrbox{\box\treebox}\hskip 0.2em % Add text, space before connection
\treectrbox{\hrule width \treewidth}%
\treectrbox{\box\treeworkbox}} % Add \hrule, subs
************************************************
% Plain TeX driver for tree.tex
\def\uncatcodespecials{\catcode`@=12\def\do##1{\catcode`##1=12}\dospecials}
\def\setupverbatim{\tt\obeylines\uncatcodespecials\obeyspaces}
{\obeyspaces\global\let =\ }
\def\beginshowoff{\par\begingroup\setupverbatim\doverbatim}
{\catcode`\!=0 \catcode`\\=12
!obeylines!gdef!doverbatim^^M#1\endshowoff{#1!endgroup!medbreak!filbreak%
!smallskip}}
% see The TeXbook, exercise 22.14
%\input tree.tex
\centerline{\bf TREE TREE}
\bigskip
\tree
{Tree}
Uses
\subtree
Computer
Science
\subtree
Data
Structures
\leaf{Search Tree}
\leaf{Priority Queue}
\endsubtree
\subtree
Parsing
\leaf{Parse Tree}
\leaf{Symbol Table}
\endsubtree
\subtree
Structured
Programming
\endsubtree
\endsubtree
\subtree
Genealogy
\leaf{Ancestors}
\leaf{Descendants}
\endsubtree
\subtree
Electrical
Engineering
\subtree
Paper
\leaf{{\it Vitae}}
\leaf{Announcements}
\leaf{Proposals}
\leaf{\TeX{} Samples}
\endsubtree
\endsubtree
\subtree
Construction
\leaf{Fences}
\subtree
Buildings
\subtree
Houses
\leaf{Human}
\leaf{Dog}
\leaf{Bird}
\leaf{Tree}
\endsubtree
\leaf{Barns}
\leaf{Other}
\endsubtree
\leaf{\dots}
\endsubtree
\subtree
Taxonomies
\leaf{Tree Uses}
\endsubtree
\endtree
\vskip.5truein
\beginshowoff
% see The TeXbook, exercise 22.14
\input tree.tex
\centerline{TREE TREE}
\bigskip
\tree
Tree
Uses
\subtree
Computer
Science
\subtree
Data
Structures
\leaf{Search Tree}
\leaf{Priority Queue}
\endsubtree
\subtree
Parsing
\leaf{Parse Tree}
\leaf{Symbol Table}
\endsubtree
\subtree
Structured
Programming
\endsubtree
\endsubtree
\subtree
Genealogy
\leaf{Ancestors}
\leaf{Descendants}
\endsubtree
\subtree
Electrical
Engineering
\subtree
Paper
\leaf{{\it Vitae}}
\leaf{Announcements}
\leaf{Proposals}
\leaf{\TeX{} Samples}
\endsubtree
\endsubtree
\subtree
Construction
\leaf{Fences}
\subtree
Buildings
\subtree
Houses
\leaf{Human}
\leaf{Dog}
\leaf{Bird}
\leaf{Tree}
\endsubtree
\leaf{Barns}
\leaf{Other}
\endsubtree
\leaf{\dots}
\endsubtree
\subtree
Taxonomies
\leaf{Tree Uses}
\endsubtree
\endtree
\endshowoff