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instiki/lib/diff/lcs.rb

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Replaced diff.rb with xhtmldiff.rb, which (unlike its predecessor) produces well-formed redline documents.
2007-02-04 05:52:48 +01:00
#! /usr/env/bin ruby
#--
# 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: lcs.rb,v 1.9 2004/10/17 20:31:10 austin Exp $
#++
module Diff
# = Diff::LCS 1.1.2
# Computes "intelligent" differences between two sequenced Enumerables.
# This is an implementation of the McIlroy-Hunt "diff" algorithm for
# Enumerable objects that include Diffable.
#
# Based on Mario I. Wolczko's <mario@wolczko.com> Smalltalk version
# (1.2, 1993) and Ned Konz's <perl@bike-nomad.com> Perl version
# (Algorithm::Diff).
#
# == Synopsis
# 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)
# seq2 == Diff::LCS.patch!(seq1, diffs)
# seq1 == Diff::LCS.unpatch(seq2, diffs)
# seq1 == Diff::LCS.unpatch!(seq2, diffs)
# seq2 == Diff::LCS.patch(seq1, sdiff)
# seq2 == Diff::LCS.patch!(seq1, sdiff)
# seq1 == Diff::LCS.unpatch(seq2, sdiff)
# seq1 == Diff::LCS.unpatch!(seq2, sdiff)
#
# Alternatively, 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)
# seq2 == seq1.patch!(diffs)
# seq1 == seq2.unpatch(diffs)
# seq1 == seq2.unpatch!(diffs)
# seq2 == seq1.patch(sdiff)
# seq2 == seq1.patch!(sdiff)
# seq1 == seq2.unpatch(sdiff)
# seq1 == seq2.unpatch!(sdiff)
#
# Default extensions are provided for Array and String objects through
# the use of 'diff/lcs/array' and 'diff/lcs/string'.
#
# == Introduction (by Mark-Jason Dominus)
#
# <em>The following text is from the Perl documentation. The only
# changes have been to make the text appear better in Rdoc</em>.
#
# I once read an article written by the authors of +diff+; they said
# that they hard worked very hard on the algorithm until they found the
# right one.
#
# I think what they ended up using (and I hope someone will correct me,
# because I am not very confident about this) was the `longest common
# subsequence' method. In the LCS problem, you have two sequences of
# items:
#
# a b c d f g h j q z
# a b c d e f g i j k r x y z
#
# and you want to find the longest sequence of items that is present in
# both original sequences in the same order. That is, you want to find a
# new sequence *S* which can be obtained from the first sequence by
# deleting some items, and from the second sequence by deleting other
# items. You also want *S* to be as long as possible. In this case *S*
# is:
#
# a b c d f g j z
#
# From there it's only a small step to get diff-like output:
#
# e h i k q r x y
# + - + + - + + +
#
# This module solves the LCS problem. It also includes a canned function
# to generate +diff+-like output.
#
# It might seem from the example above that the LCS of two sequences is
# always pretty obvious, but that's not always the case, especially when
# the two sequences have many repeated elements. For example, consider
#
# a x b y c z p d q
# a b c a x b y c z
#
# A naive approach might start by matching up the +a+ and +b+ that
# appear at the beginning of each sequence, like this:
#
# a x b y c z p d q
# a b c a b y c z
#
# This finds the common subsequence +a b c z+. But actually, the LCS is
# +a x b y c z+:
#
# a x b y c z p d q
# a b c a x b y c z
#
# == Author
# This version is by Austin Ziegler <diff-lcs@halostatue.ca>.
#
# It is based on the Perl Algorithm::Diff by Ned Konz
# <perl@bike-nomad.com>, copyright &copy; 2000 - 2002 and the Smalltalk
# diff version by Mario I. Wolczko <mario@wolczko.com>, copyright &copy;
# 1993. Documentation includes work by Mark-Jason Dominus.
#
# == Licence
# Copyright &copy; 2004 Austin Ziegler
# This program is free software; you can redistribute it and/or modify it
# under the same terms as Ruby, or alternatively under the Perl Artistic
# licence.
#
# == Credits
# Much of the documentation is taken directly from the Perl
# Algorithm::Diff implementation and was written originally by Mark-Jason
# Dominus <mjd-perl-diff@plover.com> and later by Ned Konz. The basic Ruby
# implementation was re-ported from the Smalltalk implementation, available
# at ftp://st.cs.uiuc.edu/pub/Smalltalk/MANCHESTER/manchester/4.0/diff.st
#
# #sdiff and #traverse_balanced were written for the Perl version by Mike
# Schilli <m@perlmeister.com>.
#
# "The algorithm is described in <em>A Fast Algorithm for Computing Longest
# Common Subsequences</em>, CACM, vol.20, no.5, pp.350-353, May 1977, with
# a few minor improvements to improve the speed."
module LCS
VERSION = '1.1.2'
end
end
require 'diff/lcs/callbacks'
module Diff::LCS
# Returns an Array containing the longest common subsequence(s) between
# +self+ and +other+. See Diff::LCS#LCS.
#
# lcs = seq1.lcs(seq2)
def lcs(other, &block) #:yields self[ii] if there are matched subsequences:
Diff::LCS.LCS(self, other, &block)
end
# Returns the difference set between +self+ and +other+. See
# Diff::LCS#diff.
def diff(other, callbacks = nil, &block)
Diff::LCS::diff(self, other, callbacks, &block)
end
# Returns the balanced ("side-by-side") difference set between +self+ and
# +other+. See Diff::LCS#sdiff.
def sdiff(other, callbacks = nil, &block)
Diff::LCS::sdiff(self, other, callbacks, &block)
end
# Traverses the discovered longest common subsequences between +self+ and
# +other+. See Diff::LCS#traverse_sequences.
def traverse_sequences(other, callbacks = nil, &block)
traverse_sequences(self, other, callbacks || Diff::LCS::YieldingCallbacks,
&block)
end
# Traverses the discovered longest common subsequences between +self+ and
# +other+ using the alternate, balanced algorithm. See
# Diff::LCS#traverse_balanced.
def traverse_balanced(other, callbacks = nil, &block)
traverse_balanced(self, other, callbacks || Diff::LCS::YieldingCallbacks,
&block)
end
# Attempts to patch a copy of +self+ with the provided +patchset+. See
# Diff::LCS#patch.
def patch(patchset)
Diff::LCS::patch(self.dup, patchset)
end
# Attempts to unpatch a copy of +self+ with the provided +patchset+.
# See Diff::LCS#patch.
def unpatch(patchset)
Diff::LCS::unpatch(self.dup, patchset)
end
# Attempts to patch +self+ with the provided +patchset+. See
# Diff::LCS#patch!. Does no autodiscovery.
def patch!(patchset)
Diff::LCS::patch!(self, patchset)
end
# Attempts to unpatch +self+ with the provided +patchset+. See
# Diff::LCS#unpatch. Does no autodiscovery.
def unpatch!(patchset)
Diff::LCS::unpatch!(self, patchset)
end
end
module Diff::LCS
class << self
# Given two sequenced Enumerables, LCS returns an Array containing their
# longest common subsequences.
#
# lcs = Diff::LCS.LCS(seq1, seq2)
#
# This array whose contents is such that:
#
# lcs.each_with_index do |ee, ii|
# assert(ee.nil? || (seq1[ii] == seq2[ee]))
# end
#
# If a block is provided, the matching subsequences will be yielded from
# +seq1+ in turn and may be modified before they are placed into the
# returned Array of subsequences.
def LCS(seq1, seq2, &block) #:yields seq1[ii] for each matched:
matches = Diff::LCS.__lcs(seq1, seq2)
ret = []
matches.each_with_index do |ee, ii|
unless matches[ii].nil?
if block_given?
ret << (yield seq1[ii])
else
ret << seq1[ii]
end
end
end
ret
end
# Diff::LCS.diff computes the smallest set of additions and deletions
# necessary to turn the first sequence into the second, and returns a
# description of these changes.
#
# See Diff::LCS::DiffCallbacks for the default behaviour. An alternate
# behaviour may be implemented with Diff::LCS::ContextDiffCallbacks.
# If a Class argument is provided for +callbacks+, #diff will attempt
# to initialise it. If the +callbacks+ object (possibly initialised)
# responds to #finish, it will be called.
def diff(seq1, seq2, callbacks = nil, &block) # :yields diff changes:
callbacks ||= Diff::LCS::DiffCallbacks
if callbacks.kind_of?(Class)
cb = callbacks.new rescue callbacks
callbacks = cb
end
traverse_sequences(seq1, seq2, callbacks)
callbacks.finish if callbacks.respond_to?(:finish)
if block_given?
res = callbacks.diffs.map do |hunk|
if hunk.kind_of?(Array)
hunk = hunk.map { |block| yield block }
else
yield hunk
end
end
res
else
callbacks.diffs
end
end
# Diff::LCS.sdiff computes all necessary components to show two sequences
# and their minimized differences side by side, just like the Unix
# utility <em>sdiff</em> does:
#
# old < -
# same same
# before | after
# - > new
#
# See Diff::LCS::SDiffCallbacks for the default behaviour. An alternate
# behaviour may be implemented with Diff::LCS::ContextDiffCallbacks. If
# a Class argument is provided for +callbacks+, #diff will attempt to
# initialise it. If the +callbacks+ object (possibly initialised)
# responds to #finish, it will be called.
def sdiff(seq1, seq2, callbacks = nil, &block) #:yields diff changes:
callbacks ||= Diff::LCS::SDiffCallbacks
if callbacks.kind_of?(Class)
cb = callbacks.new rescue callbacks
callbacks = cb
end
traverse_balanced(seq1, seq2, callbacks)
callbacks.finish if callbacks.respond_to?(:finish)
if block_given?
res = callbacks.diffs.map do |hunk|
if hunk.kind_of?(Array)
hunk = hunk.map { |block| yield block }
else
yield hunk
end
end
res
else
callbacks.diffs
end
end
# Diff::LCS.traverse_sequences is the most general facility provided by this
# module; +diff+ and +LCS+ are implemented as calls to it.
#
# The arguments to #traverse_sequences are the two sequences to
# traverse, and a callback object, like this:
#
# traverse_sequences(seq1, seq2, Diff::LCS::ContextDiffCallbacks.new)
#
# #diff is implemented with #traverse_sequences.
#
# == Callback Methods
# Optional callback methods are <em>emphasized</em>.
#
# callbacks#match:: Called when +a+ and +b+ are pointing
# to common elements in +A+ and +B+.
# callbacks#discard_a:: Called when +a+ is pointing to an
# element not in +B+.
# callbacks#discard_b:: Called when +b+ is pointing to an
# element not in +A+.
# <em>callbacks#finished_a</em>:: Called when +a+ has reached the end of
# sequence +A+.
# <em>callbacks#finished_b</em>:: Called when +b+ has reached the end of
# sequence +B+.
#
# == Algorithm
# a---+
# v
# A = a b c e h j l m n p
# B = b c d e f j k l m r s t
# ^
# b---+
#
# If there are two arrows (+a+ and +b+) pointing to elements of
# sequences +A+ and +B+, the arrows will initially point to the first
# elements of their respective sequences. #traverse_sequences will
# advance the arrows through the sequences one element at a time,
# calling a method on the user-specified callback object before each
# advance. It will advance the arrows in such a way that if there are
# elements <tt>A[ii]</tt> and <tt>B[jj]</tt> which are both equal and
# part of the longest common subsequence, there will be some moment
# during the execution of #traverse_sequences when arrow +a+ is pointing
# to <tt>A[ii]</tt> and arrow +b+ is pointing to <tt>B[jj]</tt>. When
# this happens, #traverse_sequences will call <tt>callbacks#match</tt>
# and then it will advance both arrows.
#
# Otherwise, one of the arrows is pointing to an element of its sequence
# that is not part of the longest common subsequence.
# #traverse_sequences will advance that arrow and will call
# <tt>callbacks#discard_a</tt> or <tt>callbacks#discard_b</tt>, depending
# on which arrow it advanced. If both arrows point to elements that are
# not part of the longest common subsequence, then #traverse_sequences
# will advance one of them and call the appropriate callback, but it is
# not specified which it will call.
#
# The methods for <tt>callbacks#match</tt>, <tt>callbacks#discard_a</tt>,
# and <tt>callbacks#discard_b</tt> are invoked with an event comprising
# the action ("=", "+", or "-", respectively), the indicies +ii+ and
# +jj+, and the elements <tt>A[ii]</tt> and <tt>B[jj]</tt>. Return
# values are discarded by #traverse_sequences.
#
# === End of Sequences
# If arrow +a+ reaches the end of its sequence before arrow +b+ does,
# #traverse_sequence try to call <tt>callbacks#finished_a</tt> with the
# last index and element of +A+ (<tt>A[-1]</tt>) and the current index
# and element of +B+ (<tt>B[jj]</tt>). If <tt>callbacks#finished_a</tt>
# does not exist, then <tt>callbacks#discard_b</tt> will be called on
# each element of +B+ until the end of the sequence is reached (the call
# will be done with <tt>A[-1]</tt> and <tt>B[jj]</tt> for each element).
#
# If +b+ reaches the end of +B+ before +a+ reaches the end of +A+,
# <tt>callbacks#finished_b</tt> will be called with the current index
# and element of +A+ (<tt>A[ii]</tt>) and the last index and element of
# +B+ (<tt>A[-1]</tt>). Again, if <tt>callbacks#finished_b</tt> does not
# exist on the callback object, then <tt>callbacks#discard_a</tt> will
# be called on each element of +A+ until the end of the sequence is
# reached (<tt>A[ii]</tt> and <tt>B[-1]</tt>).
#
# There is a chance that one additional <tt>callbacks#discard_a</tt> or
# <tt>callbacks#discard_b</tt> will be called after the end of the
# sequence is reached, if +a+ has not yet reached the end of +A+ or +b+
# has not yet reached the end of +B+.
def traverse_sequences(seq1, seq2, callbacks = Diff::LCS::SequenceCallbacks, &block) #:yields change events:
matches = Diff::LCS.__lcs(seq1, seq2)
run_finished_a = run_finished_b = false
string = seq1.kind_of?(String)
a_size = seq1.size
b_size = seq2.size
ai = bj = 0
(0 .. matches.size).each do |ii|
b_line = matches[ii]
ax = string ? seq1[ii, 1] : seq1[ii]
bx = string ? seq2[bj, 1] : seq2[bj]
if b_line.nil?
unless ax.nil?
event = Diff::LCS::ContextChange.new('-', ii, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_a(event)
end
else
loop do
break unless bj < b_line
bx = string ? seq2[bj, 1] : seq2[bj]
event = Diff::LCS::ContextChange.new('+', ii, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_b(event)
bj += 1
end
bx = string ? seq2[bj, 1] : seq2[bj]
event = Diff::LCS::ContextChange.new('=', ii, ax, bj, bx)
event = yield event if block_given?
callbacks.match(event)
bj += 1
end
ai = ii
end
ai += 1
# The last entry (if any) processed was a match. +ai+ and +bj+ point
# just past the last matching lines in their sequences.
while (ai < a_size) or (bj < b_size)
# last A?
if ai == a_size and bj < b_size
if callbacks.respond_to?(:finished_a) and not run_finished_a
ax = string ? seq1[-1, 1] : seq1[-1]
bx = string ? seq2[bj, 1] : seq2[bj]
event = Diff::LCS::ContextChange.new('>', (a_size - 1), ax, bj, bx)
event = yield event if block_given?
callbacks.finished_a(event)
run_finished_a = true
else
ax = string ? seq1[ai, 1] : seq1[ai]
loop do
bx = string ? seq2[bj, 1] : seq2[bj]
event = Diff::LCS::ContextChange.new('+', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_b(event)
bj += 1
break unless bj < b_size
end
end
end
# last B?
if bj == b_size and ai < a_size
if callbacks.respond_to?(:finished_b) and not run_finished_b
ax = string ? seq1[ai, 1] : seq1[ai]
bx = string ? seq2[-1, 1] : seq2[-1]
event = Diff::LCS::ContextChange.new('<', ai, ax, (b_size - 1), bx)
event = yield event if block_given?
callbacks.finished_b(event)
run_finished_b = true
else
bx = string ? seq2[bj, 1] : seq2[bj]
loop do
ax = string ? seq1[ai, 1] : seq1[ai]
event = Diff::LCS::ContextChange.new('-', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_a(event)
ai += 1
break unless bj < b_size
end
end
end
if ai < a_size
ax = string ? seq1[ai, 1] : seq1[ai]
bx = string ? seq2[bj, 1] : seq2[bj]
event = Diff::LCS::ContextChange.new('-', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_a(event)
ai += 1
end
if bj < b_size
ax = string ? seq1[ai, 1] : seq1[ai]
bx = string ? seq2[bj, 1] : seq2[bj]
event = Diff::LCS::ContextChange.new('+', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_b(event)
bj += 1
end
end
end
# #traverse_balanced is an alternative to #traverse_sequences. It
# uses a different algorithm to iterate through the entries in the
# computed longest common subsequence. Instead of viewing the changes as
# insertions or deletions from one of the sequences, #traverse_balanced
# will report <em>changes</em> between the sequences. To represent a
#
# The arguments to #traverse_balanced are the two sequences to traverse
# and a callback object, like this:
#
# traverse_balanced(seq1, seq2, Diff::LCS::ContextDiffCallbacks.new)
#
# #sdiff is implemented with #traverse_balanced.
#
# == Callback Methods
# Optional callback methods are <em>emphasized</em>.
#
# callbacks#match:: Called when +a+ and +b+ are pointing
# to common elements in +A+ and +B+.
# callbacks#discard_a:: Called when +a+ is pointing to an
# element not in +B+.
# callbacks#discard_b:: Called when +b+ is pointing to an
# element not in +A+.
# <em>callbacks#change</em>:: Called when +a+ and +b+ are pointing
# to the same relative position, but
# <tt>A[a]</tt> and <tt>B[b]</tt> are
# not the same; a <em>change</em> has
# occurred.
#
# #traverse_balanced might be a bit slower than #traverse_sequences,
# noticable only while processing huge amounts of data.
#
# The +sdiff+ function of this module is implemented as call to
# #traverse_balanced.
#
# == Algorithm
# a---+
# v
# A = a b c e h j l m n p
# B = b c d e f j k l m r s t
# ^
# b---+
#
# === Matches
# If there are two arrows (+a+ and +b+) pointing to elements of
# sequences +A+ and +B+, the arrows will initially point to the first
# elements of their respective sequences. #traverse_sequences will
# advance the arrows through the sequences one element at a time,
# calling a method on the user-specified callback object before each
# advance. It will advance the arrows in such a way that if there are
# elements <tt>A[ii]</tt> and <tt>B[jj]</tt> which are both equal and
# part of the longest common subsequence, there will be some moment
# during the execution of #traverse_sequences when arrow +a+ is pointing
# to <tt>A[ii]</tt> and arrow +b+ is pointing to <tt>B[jj]</tt>. When
# this happens, #traverse_sequences will call <tt>callbacks#match</tt>
# and then it will advance both arrows.
#
# === Discards
# Otherwise, one of the arrows is pointing to an element of its sequence
# that is not part of the longest common subsequence.
# #traverse_sequences will advance that arrow and will call
# <tt>callbacks#discard_a</tt> or <tt>callbacks#discard_b</tt>,
# depending on which arrow it advanced.
#
# === Changes
# If both +a+ and +b+ point to elements that are not part of the longest
# common subsequence, then #traverse_sequences will try to call
# <tt>callbacks#change</tt> and advance both arrows. If
# <tt>callbacks#change</tt> is not implemented, then
# <tt>callbacks#discard_a</tt> and <tt>callbacks#discard_b</tt> will be
# called in turn.
#
# The methods for <tt>callbacks#match</tt>, <tt>callbacks#discard_a</tt>,
# <tt>callbacks#discard_b</tt>, and <tt>callbacks#change</tt> are
# invoked with an event comprising the action ("=", "+", "-", or "!",
# respectively), the indicies +ii+ and +jj+, and the elements
# <tt>A[ii]</tt> and <tt>B[jj]</tt>. Return values are discarded by
# #traverse_balanced.
#
# === Context
# Note that +ii+ and +jj+ may not be the same index position, even if
# +a+ and +b+ are considered to be pointing to matching or changed
# elements.
def traverse_balanced(seq1, seq2, callbacks = Diff::LCS::BalancedCallbacks)
matches = Diff::LCS.__lcs(seq1, seq2)
a_size = seq1.size
b_size = seq2.size
ai = bj = mb = 0
ma = -1
string = seq1.kind_of?(String)
# Process all the lines in the match vector.
loop do
# Find next match indices +ma+ and +mb+
loop do
ma += 1
break unless ma < matches.size and matches[ma].nil?
end
break if ma >= matches.size # end of matches?
mb = matches[ma]
# Change(seq2)
while (ai < ma) or (bj < mb)
ax = string ? seq1[ai, 1] : seq1[ai]
bx = string ? seq2[bj, 1] : seq2[bj]
case [(ai < ma), (bj < mb)]
when [true, true]
if callbacks.respond_to?(:change)
event = Diff::LCS::ContextChange.new('!', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.change(event)
ai += 1
bj += 1
else
event = Diff::LCS::ContextChange.new('-', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_a(event)
ai += 1
ax = string ? seq1[ai, 1] : seq1[ai]
event = Diff::LCS::ContextChange.new('+', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_b(event)
bj += 1
end
when [true, false]
event = Diff::LCS::ContextChange.new('-', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_a(event)
ai += 1
when [false, true]
event = Diff::LCS::ContextChange.new('+', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_b(event)
bj += 1
end
end
# Match
ax = string ? seq1[ai, 1] : seq1[ai]
bx = string ? seq2[bj, 1] : seq2[bj]
event = Diff::LCS::ContextChange.new('=', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.match(event)
ai += 1
bj += 1
end
while (ai < a_size) or (bj < b_size)
ax = string ? seq1[ai, 1] : seq1[ai]
bx = string ? seq2[bj, 1] : seq2[bj]
case [(ai < a_size), (bj < b_size)]
when [true, true]
if callbacks.respond_to?(:change)
event = Diff::LCS::ContextChange.new('!', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.change(event)
ai += 1
bj += 1
else
event = Diff::LCS::ContextChange.new('-', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_a(event)
ai += 1
ax = string ? seq1[ai, 1] : seq1[ai]
event = Diff::LCS::ContextChange.new('+', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_b(event)
bj += 1
end
when [true, false]
event = Diff::LCS::ContextChange.new('-', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_a(event)
ai += 1
when [false, true]
event = Diff::LCS::ContextChange.new('+', ai, ax, bj, bx)
event = yield event if block_given?
callbacks.discard_b(event)
bj += 1
end
end
end
PATCH_MAP = { #:nodoc:
:patch => { '+' => '+', '-' => '-', '!' => '!', '=' => '=' },
:unpatch => { '+' => '-', '-' => '+', '!' => '!', '=' => '=' }
}
# Given a patchset, convert the current version to the new
# version. If +direction+ is not specified (must be
# <tt>:patch</tt> or <tt>:unpatch</tt>), then discovery of the
# direction of the patch will be attempted.
def patch(src, patchset, direction = nil)
string = src.kind_of?(String)
# Start with a new empty type of the source's class
res = src.class.new
# Normalize the patchset.
patchset = __normalize_patchset(patchset)
direction ||= Diff::LCS.__diff_direction(src, patchset)
direction ||= :patch
ai = bj = 0
patchset.each do |change|
# Both Change and ContextChange support #action
action = PATCH_MAP[direction][change.action]
case change
when Diff::LCS::ContextChange
case direction
when :patch
el = change.new_element
op = change.old_position
np = change.new_position
when :unpatch
el = change.old_element
op = change.new_position
np = change.old_position
end
case action
when '-' # Remove details from the old string
while ai < op
res << (string ? src[ai, 1] : src[ai])
ai += 1
bj += 1
end
ai += 1
when '+'
while bj < np
res << (string ? src[ai, 1] : src[ai])
ai += 1
bj += 1
end
res << el
bj += 1
when '='
# This only appears in sdiff output with the SDiff callback.
# Therefore, we only need to worry about dealing with a single
# element.
res << el
ai += 1
bj += 1
when '!'
while ai < op
res << (string ? src[ai, 1] : src[ai])
ai += 1
bj += 1
end
bj += 1
ai += 1
res << el
end
when Diff::LCS::Change
case action
when '-'
while ai < change.position
res << (string ? src[ai, 1] : src[ai])
ai += 1
bj += 1
end
ai += 1
when '+'
while bj < change.position
res << (string ? src[ai, 1] : src[ai])
ai += 1
bj += 1
end
bj += 1
res << change.element
end
end
end
while ai < src.size
res << (string ? src[ai, 1] : src[ai])
ai += 1
bj += 1
end
res
end
# Given a set of patchset, convert the current version to the prior
# version. Does no auto-discovery.
def unpatch!(src, patchset)
Diff::LCS.patch(src, patchset, :unpatch)
end
# Given a set of patchset, convert the current version to the next
# version. Does no auto-discovery.
def patch!(src, patchset)
Diff::LCS.patch(src, patchset, :patch)
end
# private
# Compute the longest common subsequence between the sequenced Enumerables
# +a+ and +b+. The result is an array whose contents is such that
#
# result = Diff::LCS.__lcs(a, b)
# result.each_with_index do |e, ii|
# assert_equal(a[ii], b[e]) unless e.nil?
# end
def __lcs(a, b)
a_start = b_start = 0
a_finish = a.size - 1
b_finish = b.size - 1
vector = []
# Prune off any common elements at the beginning...
while (a_start <= a_finish) and
(b_start <= b_finish) and
(a[a_start] == b[b_start])
vector[a_start] = b_start
a_start += 1
b_start += 1
end
# Now the end...
while (a_start <= a_finish) and
(b_start <= b_finish) and
(a[a_finish] == b[b_finish])
vector[a_finish] = b_finish
a_finish -= 1
b_finish -= 1
end
# Now, compute the equivalence classes of positions of elements.
b_matches = Diff::LCS.__position_hash(b, b_start .. b_finish)
thresh = []
links = []
(a_start .. a_finish).each do |ii|
ai = a.kind_of?(String) ? a[ii, 1] : a[ii]
bm = b_matches[ai]
kk = nil
bm.reverse_each do |jj|
if kk and (thresh[kk] > jj) and (thresh[kk - 1] < jj)
thresh[kk] = jj
else
kk = Diff::LCS.__replace_next_larger(thresh, jj, kk)
end
links[kk] = [ (kk > 0) ? links[kk - 1] : nil, ii, jj ] unless kk.nil?
end
end
unless thresh.empty?
link = links[thresh.size - 1]
while not link.nil?
vector[link[1]] = link[2]
link = link[0]
end
end
vector
end
# Find the place at which +value+ would normally be inserted into the
# Enumerable. If that place is already occupied by +value+, do nothing
# and return +nil+. If the place does not exist (i.e., it is off the end
# of the Enumerable), add it to the end. Otherwise, replace the element
# at that point with +value+. It is assumed that the Enumerable's values
# are numeric.
#
# This operation preserves the sort order.
def __replace_next_larger(enum, value, last_index = nil)
# Off the end?
if enum.empty? or (value > enum[-1])
enum << value
return enum.size - 1
end
# Binary search for the insertion point
last_index ||= enum.size
first_index = 0
while (first_index <= last_index)
ii = (first_index + last_index) >> 1
found = enum[ii]
if value == found
return nil
elsif value > found
first_index = ii + 1
else
last_index = ii - 1
end
end
# The insertion point is in first_index; overwrite the next larger
# value.
enum[first_index] = value
return first_index
end
# If +vector+ maps the matching elements of another collection onto this
# Enumerable, compute the inverse +vector+ that maps this Enumerable
# onto the collection. (Currently unused.)
def __inverse_vector(a, vector)
inverse = a.dup
(0 ... vector.size).each do |ii|
inverse[vector[ii]] = ii unless vector[ii].nil?
end
inverse
end
# Returns a hash mapping each element of an Enumerable to the set of
# positions it occupies in the Enumerable, optionally restricted to the
# elements specified in the range of indexes specified by +interval+.
def __position_hash(enum, interval = 0 .. -1)
hash = Hash.new { |hh, kk| hh[kk] = [] }
interval.each do |ii|
kk = enum.kind_of?(String) ? enum[ii, 1] : enum[ii]
hash[kk] << ii
end
hash
end
# Examine the patchset and the source to see in which direction the
# patch should be applied.
#
# WARNING: By default, this examines the whole patch, so this could take
# some time. This also works better with Diff::LCS::ContextChange or
# Diff::LCS::Change as its source, as an array will cause the creation
# of one of the above.
def __diff_direction(src, patchset, limit = nil)
count = left = left_miss = right = right_miss = 0
string = src.kind_of?(String)
patchset.each do |change|
count += 1
case change
when Diff::LCS::Change
# With a simplistic change, we can't tell the difference between
# the left and right on '!' actions, so we ignore those. On '='
# actions, if there's a miss, we miss both left and right.
element = string ? src[change.position, 1] : src[change.position]
case change.action
when '-'
if element == change.element
left += 1
else
left_miss += 1
end
when '+'
if element == change.element
right += 1
else
right_miss += 1
end
when '='
if element != change.element
left_miss += 1
right_miss += 1
end
end
when Diff::LCS::ContextChange
case change.action
when '-' # Remove details from the old string
element = string ? src[change.old_position, 1] : src[change.old_position]
if element == change.old_element
left += 1
else
left_miss += 1
end
when '+'
element = string ? src[change.new_position, 1] : src[change.new_position]
if element == change.new_element
right += 1
else
right_miss += 1
end
when '='
le = string ? src[change.old_position, 1] : src[change.old_position]
re = string ? src[change.new_position, 1] : src[change.new_position]
left_miss += 1 if le != change.old_element
right_miss += 1 if re != change.new_element
when '!'
element = string ? src[change.old_position, 1] : src[change.old_position]
if element == change.old_element
left += 1
else
element = string ? src[change.new_position, 1] : src[change.new_position]
if element == change.new_element
right += 1
else
left_miss += 1
right_miss += 1
end
end
end
end
break if not limit.nil? and count > limit
end
no_left = (left == 0) and (left_miss >= 0)
no_right = (right == 0) and (right_miss >= 0)
case [no_left, no_right]
when [false, true]
return :patch
when [true, false]
return :unpatch
else
raise "The provided patchset does not appear to apply to the provided value as either source or destination value."
end
end
# Normalize the patchset. A patchset is always a sequence of changes, but
# how those changes are represented may vary, depending on how they were
# generated. In all cases we support, we also support the array
# representation of the changes. The formats are:
#
# [ # patchset <- Diff::LCS.diff(a, b)
# [ # one or more hunks
# Diff::LCS::Change # one or more changes
# ] ]
#
# [ # patchset, equivalent to the above
# [ # one or more hunks
# [ action, line, value ] # one or more changes
# ] ]
#
# [ # patchset <- Diff::LCS.diff(a, b, Diff::LCS::ContextDiffCallbacks)
# # OR <- Diff::LCS.sdiff(a, b, Diff::LCS::ContextDiffCallbacks)
# [ # one or more hunks
# Diff::LCS::ContextChange # one or more changes
# ] ]
#
# [ # patchset, equivalent to the above
# [ # one or more hunks
# [ action, [ old line, old value ], [ new line, new value ] ]
# # one or more changes
# ] ]
#
# [ # patchset <- Diff::LCS.sdiff(a, b)
# # OR <- Diff::LCS.diff(a, b, Diff::LCS::SDiffCallbacks)
# Diff::LCS::ContextChange # one or more changes
# ]
#
# [ # patchset, equivalent to the above
# [ action, [ old line, old value ], [ new line, new value ] ]
# # one or more changes
# ]
#
# The result of this will be either of the following.
#
# [ # patchset
# Diff::LCS::ContextChange # one or more changes
# ]
#
# [ # patchset
# Diff::LCS::Change # one or more changes
# ]
#
# If either of the above is provided, it will be returned as such.
#
def __normalize_patchset(patchset)
patchset.map do |hunk|
case hunk
when Diff::LCS::ContextChange, Diff::LCS::Change
hunk
when Array
if (not hunk[0].kind_of?(Array)) and hunk[1].kind_of?(Array) and hunk[2].kind_of?(Array)
Diff::LCS::ContextChange.from_a(hunk)
else
hunk.map do |change|
case change
when Diff::LCS::ContextChange, Diff::LCS::Change
change
when Array
# change[1] will ONLY be an array in a ContextChange#to_a call.
# In Change#to_a, it represents the line (singular).
if change[1].kind_of?(Array)
Diff::LCS::ContextChange.from_a(change)
else
Diff::LCS::Change.from_a(change)
end
end
end
end
else
raise ArgumentError, "Cannot normalise a hunk of class #{hunk.class}."
end
end.flatten
end
end
end
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