[ANN] Diff::LCS 1.0

[Austin Ziegler]

I've been very busy lately on an ancillary project for Ruwiki because
of a licence issue with Algorithm:iff. Thus, I happily announce the
release of Diff::LCS. There may be an interim Ruwiki update with this
change soon. It's available from RubyForge under the Ruwiki project.
For the moment, the documentation is entirely self-contained; there
will be updated documentation pages in the not-too-distant future.

-austin

Diff::LCS README
================
This is the 1.0 release of Diff::LCS for Ruby, based originally on Perl's
Algorithm:iff[1]. It uses the McIlroy-Hunt longest common subsequence (LCS)
algorithm to compute intelligent differences between two sequenced enumerable
containers[2]. The implementation is based on Mario I. Wolczko's[3] Smalltalk
version (1.2, 1993)[4] and Ned Konz's[5] Perl version (Algorithm:iff)[6].

Using this module is quite simple. By default, Diff::LCS does not extend
objects with the Diff::LCS interface, but will be called as if it were a
function:

require 'diff/lcs'

seq1 = %w(a b c e h j l m n p)
seq2 = %w(b c d e f j k l m r s t)

lcs = Diff::LCS.LCS(seq1, seq2)
diffs = Diff::LCS.diff(seq1, seq2)
sdiff = Diff::LCS.sdiff(seq1, seq2)
seq = Diff::LCS.traverse_sequences(seq1, seq2, callback_obj)
bal = Diff::LCS.traverse_balanced(seq1, seq2, callback_obj)

Objects can be extended with Diff::LCS:

seq1.extend(Diff::LCS)
lcs = seq1.lcs(seq2)
diffs = seq1.diff(seq2)
sdiff = seq1.sdiff(seq2)
seq = Diff::LCS.traverse_sequences(seq1, seq2, callback_obj)
bal = Diff::LCS.traverse_balanced(seq1, seq2, callback_obj)

By requiring 'diff/lcs/array' or 'diff/lcs/string', Array or String
will be extended for use this way.

Copyright
=========
#--
# Copyright 2004 Austin Ziegler <[email protected]>
# adapted from:
# Algorithm:iff (Perl) by Ned Konz <[email protected]>
# Smalltalk by Mario I. Wolczko <[email protected]>
# implements McIlroy-Hunt diff algorithm
#
# This program is free software. It may be redistributed and/or modified under
# the terms of the GPL version 2 (or later), the Perl Artistic licence, or the
# Ruby licence.
#
# $Id: README,v 1.1 2004/07/04 14:49:31 austin Exp $
#++

Footnotes
=========
[1] This library is called Diff::LCS because there are multiple
Ruby libraries called Algorithm:iff maintained by other authors.
[2] By sequenced enumerable, I mean that the orderr of enumeration is
predictable and consistent for the same set of data. While it is
theoretically possible to generate a diff for unordereded hash, it
will only be meaningful if the enumeration of the hashes is
consistent. In general, this will mean that containers that behave
like String or Array will perform best.
[3] (e-mail address removed)
[4] ftp://st.cs.uiuc.edu/pub/Smalltalk/MANCHESTER/manchester/4.0/diff.st
[5] (e-mail address removed)
[6] http://search.cpan.org/~nedkonz/Algorithm-Diff-1.15/