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Ruby/RBTree

RBTree is a sorted associative collection that is implemented with Red-Black Tree. The elements of RBTree are ordered and its interface is the almost same as Hash, so simply you can consider RBTree sorted Hash.

Red-Black Tree is a kind of binary tree that automatically balances by itself when a node is inserted or deleted. Thus the complexity for insert, search and delete is O(log N) in expected and worst case. On the other hand the complexity of Hash is O(1). Because Hash is unordered the data structure is more effective than Red-Black Tree as an associative collection.

The elements of RBTree are sorted with natural ordering (by <=> method) of its keys or by a comparator(Proc) set by readjust method. It means all keys in RBTree should be comparable with each other. Or a comparator that takes two arguments of a key should return negative, 0, or positive depending on the first argument is less than, equal to, or greater than the second one.

The interface of RBTree is the almost same as Hash and there are a few methods to take advantage of the ordering:

* lower_bound, upper_bound, bound
* first, last
* shift, pop
* reverse_each

Note: while iterating RBTree (e.g. in a block of each method), it is not modifiable, or TypeError is thrown.

RBTree supoorts pretty printing using pp.

This library contains two classes. One is RBTree and the other is MultiRBTree that is a parent class of RBTree. RBTree does not allow duplications of keys but MultiRBTree does.

require "rbtree"

rbtree = RBTree["c", 10, "a", 20]
rbtree["b"] = 30
p rbtree["b"]              # => 30
rbtree.each do |k, v|
  p [k, v]
end                        # => ["a", 20] ["b", 30] ["c", 10]

mrbtree = MultiRBTree["c", 10, "a", 20, "e", 30, "a", 40]
p mrbtree.lower_bound("b") # => ["c", 10]
mrbtree.bound("a", "d") do |k, v|
  p [k, v]
end                        # => ["a", 20] ["a", 40] ["c", 10]

Requirement

* Ruby 1.8.x

Install

$ sudo gem install rbtree

or download a tarball from the link below

* ((<"Ruby/RBTree 0.2.1"|URL:rbtree-0.2.1.tar.gz>))

and then

$ tar xzf rbtree-x.x.x.tar.gz
$ cd rbtree-x.x.x.tar.gz
$ ruby extconf.rb
$ make
$ sudo make site-install

Test

$ ruby test.rb

Incomplete Documents

$ rdoc rbtree.c

or online documents at ((<URL:rbtree.rubyforge.org/>)).

License

dict.c and dict.h are modified copies that are originally in Kazlib written by Kaz Kylheku. Copyright is held by Kaz Kylheku, see dict.c and dict.h for the license. The web page of Kazlib is at ((<URL:users.footprints.net/~kaz/kazlib.html>)).

Support

Bug fixes, suggestions and other feedbacks are welcomed. Please mail me at burningdowntheopera at yahoo dot co dot jp.

Links

* ((<RAA - ruby-rbtree|URL:http://raa.ruby-lang.org/project/ruby-rbtree/>))
* ((<RubyForge: rbtree: Project Info|URL:http://rubyforge.org/projects/rbtree/>))
* ((<URL:http://www.geocities.co.jp/SiliconValley-PaloAlto/3388/rbtree/README.html>))