--- /dev/null
+README for Tree::DAG_Node
+
+ Tree::DAG_Node
+ version 1.06
+
+[Partially excerpted from the POD.]
+
+Tree::DAG_Node is a (super)class for representing nodes in a tree.
+
+This class encapsulates/makes/manipulates objects that represent nodes
+in a tree structure. The tree structure is not an object itself, but
+is emergent from the linkages you create between nodes. This class
+provides the methods for making linkages that can be used to build up
+a tree, while preventing you from ever making any kinds of linkages
+which are not allowed in a tree (such as having a node be its own
+mother or ancestor, or having a node have two mothers).
+
+This is what I mean by a "tree structure", a bit redundantly stated:
+
+ * A tree is a special case of an acyclic directed graph.
+
+ * A tree is a network of nodes where there's exactly one root node
+ (i.e., 'the top'), and the only primary relationship between nodes
+ is the mother-daugher relationship.
+
+ * No node can be its own mother, or its mother's mother, etc.
+
+ * Each node in the tree has exactly one "parent" (node in the "up"
+ direction) -- except the root, which is parentless.
+
+ * Each node can have any number (0 to any finite number) of
+ daughter nodes. A given node's daughter nodes constitute an
+ *ordered* list. (However, you are free to consider this ordering
+ irrelevant. Some applications do need daughters to be ordered, so
+ I chose to consider this the general case.)
+
+ * A node can appear in only one tree, and only once in that tree.
+ Notably (notable because it doesn't follow from the two above
+ points), a node cannot appear twice in its mother's daughter list.
+
+ * In other words, there's an idea of up (toward the root) versus
+ down (away from the root), and left (i.e., toward the start (index
+ 0) of a given node's daughter list) versus right (toward the end
+ of a given node's daughter list).
+
+Trees as described above have various applications, among them:
+representing syntactic constituency, in formal linguistics;
+representing contingencies in a game tree; representing abstract
+syntax in the parsing of any computer language -- whether in
+expression trees for programming languages, or constituency in the
+parse of a markup language document. (Some of these might not use the
+fact that daughters are ordered.)
+
+Note: B-Trees are a very special case of the above kinds of trees, and
+are best treated with their own class. Check CPAN for modules
+encapsulating B-Trees; or if you actually want a database, and for
+some reason ended up looking here, go look at the AnyDBM_File
+manpage.)
+
+Many base classes are not usable except as such -- but Tree::DAG_Node
+can be used as a normal class.
+
+
+PREREQUISITES
+
+This suite requires Perl 5; I've only used it under Perl 5.004, so for
+anything lower, you're on your own.
+
+Tree::DAG_Node doesn't use any nonstandard modules.
+
+
+INSTALLATION
+
+You install Tree::DAG_Node, as you would install any perl module
+library, by running these commands:
+
+ perl Makefile.PL
+ make
+ make test
+ make install
+
+If you want to install a private copy of Tree::DAG_Node in your home
+directory, then you should try to produce the initial Makefile with
+something like this command:
+
+ perl Makefile.PL LIB=~/perl
+
+Then you may need something like
+ setenv PERLLIB "$HOME/perl"
+in your shell initialization file (e.g., ~/.cshrc).
+
+See perldoc perlmodinstall for more information on installing modules.
+
+
+DOCUMENTATION
+
+POD-format documentation is included in DAG_Node.pm. POD is readable
+with the 'perldoc' utility. See ChangeLog for recent changes.
+
+
+MACPERL INSTALLATION NOTES
+
+Don't bother with the makefiles. Just make a Tree directory in your
+MacPerl site_lib or lib directory, and move DAG_Node.pm into there.
+
+
+SUPPORT
+
+Questions, bug reports, useful code bits, and suggestions for
+Tree::DAG_Node should just be sent to David Hand, <cogent@cpan.org>.
+
+
+AVAILABILITY
+
+The latest version of Tree::DAG_Node is available from the Comprehensive
+Perl Archive Network (CPAN). Visit <http://www.perl.com/CPAN/> to find
+a CPAN site near you.
+
+
+COPYRIGHT AND LICENSE
+
+Copyright 1998-2001, 2004, 2007 by Sean M. Burke and David Hand.
+
+This program is free software; you can redistribute it and/or modify it
+under the same terms as Perl itself.
projects / dh-make-perl / blobdiff