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Diff::LCS README
================
Diff::LCS is a port of Algorithm::Diff[1] that 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::Diff)[6].
This release is version 1.1.2, fixing an htmldiff bug in 1.1.1. Version 1.1.0
added new features, including the ability to #patch and #unpatch changes as
well as a new contextual diff callback, Diff::LCS::ContextDiffCallbacks, that
should improve the context sensitivity of patching.
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)
seq2 == Diff::LCS.patch!(seq1, diffs)
seq1 == Diff::LCS.unpatch!(seq2, diffs)
seq2 == Diff::LCS.patch!(seq1, sdiff)
seq1 == Diff::LCS.unpatch!(seq2, sdiff)
Objects can be extended with Diff::LCS:
seq1.extend(Diff::LCS)
lcs = seq1.lcs(seq2)
diffs = seq1.diff(seq2)
sdiff = seq1.sdiff(seq2)
seq = seq1.traverse_sequences(seq2, callback_obj)
bal = seq1.traverse_balanced(seq2, callback_obj)
seq2 == seq1.patch!(diffs)
seq1 == seq2.unpatch!(diffs)
seq2 == seq1.patch!(sdiff)
seq1 == seq2.unpatch!(sdiff)
By requiring 'diff/lcs/array' or 'diff/lcs/string', Array or String will
be extended for use this way.
Copyright
=========
# Copyright 2004 Austin Ziegler <diff-lcs@halostatue.ca>
# adapted from:
# Algorithm::Diff (Perl) by Ned Konz <perl@bike-nomad.com>
# Smalltalk by Mario I. Wolczko <mario@wolczko.com>
# 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.
#
# $Id$
Footnotes
=========
[1] This library is called Diff::LCS because there are multiple
Ruby libraries called Algorithm::Diff maintained by other authors.
[2] By sequenced enumerable, I mean that the order 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] mario@wolczko.com
[4] ftp://st.cs.uiuc.edu/pub/Smalltalk/MANCHESTER/manchester/4.0/diff.st
[5] perl@bike-nomad.com
[6] http://search.cpan.org/~nedkonz/Algorithm-Diff-1.15/
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