323 lines
11 KiB
Ruby
323 lines
11 KiB
Ruby
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#! /usr/env/bin ruby
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#--
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# Copyright 2004 Austin Ziegler <diff-lcs@halostatue.ca>
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# adapted from:
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# Algorithm::Diff (Perl) by Ned Konz <perl@bike-nomad.com>
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# Smalltalk by Mario I. Wolczko <mario@wolczko.com>
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# implements McIlroy-Hunt diff algorithm
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#
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# This program is free software. It may be redistributed and/or modified under
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# the terms of the GPL version 2 (or later), the Perl Artistic licence, or the
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# Ruby licence.
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#
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# $Id: callbacks.rb,v 1.4 2004/09/14 18:51:26 austin Exp $
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#++
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# Contains definitions for all default callback objects.
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require 'diff/lcs/change'
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module Diff::LCS
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# This callback object implements the default set of callback events, which
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# only returns the event itself. Note that #finished_a and #finished_b are
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# not implemented -- I haven't yet figured out where they would be useful.
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#
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# Note that this is intended to be called as is, e.g.,
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#
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# Diff::LCS.LCS(seq1, seq2, Diff::LCS::DefaultCallbacks)
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class DefaultCallbacks
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class << self
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# Called when two items match.
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def match(event)
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event
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end
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# Called when the old value is discarded in favour of the new value.
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def discard_a(event)
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event
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end
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# Called when the new value is discarded in favour of the old value.
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def discard_b(event)
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event
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end
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# Called when both the old and new values have changed.
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def change(event)
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event
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end
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private :new
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end
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end
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# An alias for DefaultCallbacks that is used in Diff::LCS#traverse_sequences.
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#
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# Diff::LCS.LCS(seq1, seq2, Diff::LCS::SequenceCallbacks)
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SequenceCallbacks = DefaultCallbacks
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# An alias for DefaultCallbacks that is used in Diff::LCS#traverse_balanced.
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#
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# Diff::LCS.LCS(seq1, seq2, Diff::LCS::BalancedCallbacks)
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BalancedCallbacks = DefaultCallbacks
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end
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# This will produce a compound array of simple diff change objects. Each
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# element in the #diffs array is a +hunk+ or +hunk+ array, where each
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# element in each +hunk+ array is a single Change object representing the
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# addition or removal of a single element from one of the two tested
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# sequences. The +hunk+ provides the full context for the changes.
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#
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# diffs = Diff::LCS.diff(seq1, seq2)
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# # This example shows a simplified array format.
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# # [ [ [ '-', 0, 'a' ] ], # 1
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# # [ [ '+', 2, 'd' ] ], # 2
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# # [ [ '-', 4, 'h' ], # 3
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# # [ '+', 4, 'f' ] ],
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# # [ [ '+', 6, 'k' ] ], # 4
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# # [ [ '-', 8, 'n' ], # 5
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# # [ '-', 9, 'p' ],
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# # [ '+', 9, 'r' ],
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# # [ '+', 10, 's' ],
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# # [ '+', 11, 't' ] ] ]
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#
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# There are five hunks here. The first hunk says that the +a+ at position 0
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# of the first sequence should be deleted (<tt>'-'</tt>). The second hunk
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# says that the +d+ at position 2 of the second sequence should be inserted
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# (<tt>'+'</tt>). The third hunk says that the +h+ at position 4 of the
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# first sequence should be removed and replaced with the +f+ from position 4
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# of the second sequence. The other two hunks are described similarly.
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#
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# === Use
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# This callback object must be initialised and is used by the Diff::LCS#diff
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# method.
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#
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# cbo = Diff::LCS::DiffCallbacks.new
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# Diff::LCS.LCS(seq1, seq2, cbo)
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# cbo.finish
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#
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# Note that the call to #finish is absolutely necessary, or the last set of
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# changes will not be visible. Alternatively, can be used as:
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#
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# cbo = Diff::LCS::DiffCallbacks.new { |tcbo| Diff::LCS.LCS(seq1, seq2, tcbo) }
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#
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# The necessary #finish call will be made.
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#
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# === Simplified Array Format
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# The simplified array format used in the example above can be obtained
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# with:
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#
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# require 'pp'
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# pp diffs.map { |e| e.map { |f| f.to_a } }
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class Diff::LCS::DiffCallbacks
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# Returns the difference set collected during the diff process.
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attr_reader :diffs
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def initialize # :yields self:
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@hunk = []
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@diffs = []
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if block_given?
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begin
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yield self
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ensure
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self.finish
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end
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end
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end
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# Finalizes the diff process. If an unprocessed hunk still exists, then it
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# is appended to the diff list.
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def finish
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add_nonempty_hunk
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end
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def match(event)
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add_nonempty_hunk
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end
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def discard_a(event)
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@hunk << Diff::LCS::Change.new('-', event.old_position, event.old_element)
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end
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def discard_b(event)
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@hunk << Diff::LCS::Change.new('+', event.new_position, event.new_element)
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end
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private
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def add_nonempty_hunk
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@diffs << @hunk unless @hunk.empty?
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@hunk = []
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end
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end
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# This will produce a compound array of contextual diff change objects. Each
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# element in the #diffs array is a "hunk" array, where each element in each
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# "hunk" array is a single change. Each change is a Diff::LCS::ContextChange
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# that contains both the old index and new index values for the change. The
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# "hunk" provides the full context for the changes. Both old and new objects
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# will be presented for changed objects. +nil+ will be substituted for a
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# discarded object.
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#
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# seq1 = %w(a b c e h j l m n p)
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# seq2 = %w(b c d e f j k l m r s t)
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#
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# diffs = Diff::LCS.diff(seq1, seq2, Diff::LCS::ContextDiffCallbacks)
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# # This example shows a simplified array format.
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# # [ [ [ '-', [ 0, 'a' ], [ 0, nil ] ] ], # 1
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# # [ [ '+', [ 3, nil ], [ 2, 'd' ] ] ], # 2
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# # [ [ '-', [ 4, 'h' ], [ 4, nil ] ], # 3
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# # [ '+', [ 5, nil ], [ 4, 'f' ] ] ],
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# # [ [ '+', [ 6, nil ], [ 6, 'k' ] ] ], # 4
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# # [ [ '-', [ 8, 'n' ], [ 9, nil ] ], # 5
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# # [ '+', [ 9, nil ], [ 9, 'r' ] ],
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# # [ '-', [ 9, 'p' ], [ 10, nil ] ],
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# # [ '+', [ 10, nil ], [ 10, 's' ] ],
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# # [ '+', [ 10, nil ], [ 11, 't' ] ] ] ]
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#
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# The five hunks shown are comprised of individual changes; if there is a
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# related set of changes, they are still shown individually.
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#
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# This callback can also be used with Diff::LCS#sdiff, which will produce
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# results like:
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#
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# diffs = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextCallbacks)
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# # This example shows a simplified array format.
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# # [ [ [ "-", [ 0, "a" ], [ 0, nil ] ] ], # 1
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# # [ [ "+", [ 3, nil ], [ 2, "d" ] ] ], # 2
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# # [ [ "!", [ 4, "h" ], [ 4, "f" ] ] ], # 3
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# # [ [ "+", [ 6, nil ], [ 6, "k" ] ] ], # 4
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# # [ [ "!", [ 8, "n" ], [ 9, "r" ] ], # 5
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# # [ "!", [ 9, "p" ], [ 10, "s" ] ],
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# # [ "+", [ 10, nil ], [ 11, "t" ] ] ] ]
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#
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# The five hunks are still present, but are significantly shorter in total
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# presentation, because changed items are shown as changes ("!") instead of
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# potentially "mismatched" pairs of additions and deletions.
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#
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# The result of this operation is similar to that of
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# Diff::LCS::SDiffCallbacks. They may be compared as:
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#
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# s = Diff::LCS.sdiff(seq1, seq2).reject { |e| e.action == "=" }
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# c = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextDiffCallbacks).flatten
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#
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# s == c # -> true
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#
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# === Use
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# This callback object must be initialised and can be used by the
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# Diff::LCS#diff or Diff::LCS#sdiff methods.
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#
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# cbo = Diff::LCS::ContextDiffCallbacks.new
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# Diff::LCS.LCS(seq1, seq2, cbo)
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# cbo.finish
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#
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# Note that the call to #finish is absolutely necessary, or the last set of
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# changes will not be visible. Alternatively, can be used as:
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#
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# cbo = Diff::LCS::ContextDiffCallbacks.new { |tcbo| Diff::LCS.LCS(seq1, seq2, tcbo) }
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#
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# The necessary #finish call will be made.
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#
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# === Simplified Array Format
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# The simplified array format used in the example above can be obtained
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# with:
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#
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# require 'pp'
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# pp diffs.map { |e| e.map { |f| f.to_a } }
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class Diff::LCS::ContextDiffCallbacks < Diff::LCS::DiffCallbacks
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def discard_a(event)
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@hunk << Diff::LCS::ContextChange.simplify(event)
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end
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def discard_b(event)
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@hunk << Diff::LCS::ContextChange.simplify(event)
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end
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def change(event)
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@hunk << Diff::LCS::ContextChange.simplify(event)
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end
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end
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# This will produce a simple array of diff change objects. Each element in
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# the #diffs array is a single ContextChange. In the set of #diffs provided
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# by SDiffCallbacks, both old and new objects will be presented for both
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# changed <strong>and unchanged</strong> objects. +nil+ will be substituted
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# for a discarded object.
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#
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# The diffset produced by this callback, when provided to Diff::LCS#sdiff,
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# will compute and display the necessary components to show two sequences
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# and their minimized differences side by side, just like the Unix utility
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# +sdiff+.
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#
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# same same
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# before | after
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# old < -
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# - > new
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#
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# seq1 = %w(a b c e h j l m n p)
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# seq2 = %w(b c d e f j k l m r s t)
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#
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# diffs = Diff::LCS.sdiff(seq1, seq2)
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# # This example shows a simplified array format.
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# # [ [ "-", [ 0, "a"], [ 0, nil ] ],
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# # [ "=", [ 1, "b"], [ 0, "b" ] ],
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# # [ "=", [ 2, "c"], [ 1, "c" ] ],
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# # [ "+", [ 3, nil], [ 2, "d" ] ],
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# # [ "=", [ 3, "e"], [ 3, "e" ] ],
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# # [ "!", [ 4, "h"], [ 4, "f" ] ],
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# # [ "=", [ 5, "j"], [ 5, "j" ] ],
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# # [ "+", [ 6, nil], [ 6, "k" ] ],
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# # [ "=", [ 6, "l"], [ 7, "l" ] ],
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# # [ "=", [ 7, "m"], [ 8, "m" ] ],
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# # [ "!", [ 8, "n"], [ 9, "r" ] ],
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# # [ "!", [ 9, "p"], [ 10, "s" ] ],
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# # [ "+", [ 10, nil], [ 11, "t" ] ] ]
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#
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# The result of this operation is similar to that of
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# Diff::LCS::ContextDiffCallbacks. They may be compared as:
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#
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# s = Diff::LCS.sdiff(seq1, seq2).reject { |e| e.action == "=" }
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# c = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextDiffCallbacks).flatten
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#
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# s == c # -> true
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#
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# === Use
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# This callback object must be initialised and is used by the Diff::LCS#sdiff
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# method.
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#
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# cbo = Diff::LCS::SDiffCallbacks.new
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# Diff::LCS.LCS(seq1, seq2, cbo)
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#
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# As with the other initialisable callback objects, Diff::LCS::SDiffCallbacks
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# can be initialised with a block. As there is no "fininishing" to be done,
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# this has no effect on the state of the object.
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#
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# cbo = Diff::LCS::SDiffCallbacks.new { |tcbo| Diff::LCS.LCS(seq1, seq2, tcbo) }
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#
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# === Simplified Array Format
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# The simplified array format used in the example above can be obtained
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# with:
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#
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# require 'pp'
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# pp diffs.map { |e| e.to_a }
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class Diff::LCS::SDiffCallbacks
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# Returns the difference set collected during the diff process.
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attr_reader :diffs
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def initialize #:yields self:
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@diffs = []
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yield self if block_given?
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end
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def match(event)
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@diffs << Diff::LCS::ContextChange.simplify(event)
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end
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def discard_a(event)
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@diffs << Diff::LCS::ContextChange.simplify(event)
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end
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def discard_b(event)
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@diffs << Diff::LCS::ContextChange.simplify(event)
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end
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def change(event)
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@diffs << Diff::LCS::ContextChange.simplify(event)
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end
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end
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