480 lines
13 KiB
Ruby
480 lines
13 KiB
Ruby
# heavily based off difflib.py - see that file for documentation
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# ported from Python by Bill Atkins
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# This does not support all features offered by difflib; it
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# implements only the subset of features necessary
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# to support a Ruby version of HTML Differ. You're welcome to finish this off.
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# By default, String#each iterates by line. This isn't really appropriate
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# for diff, so often a string will be split by // to get an array of one-
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# character strings.
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# Some methods in Diff are untested and are not guaranteed to work. The
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# methods in HTMLDiff and any methods it calls should work quite well.
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# changes by DenisMertz
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# * main change:
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# ** get the tag soup away
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# the tag soup problem was first reported with <p> tags, but it appeared also with
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# <li>, <ul> etc... tags
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# this version should mostly fix these problems
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# ** added a Builder class to manage the creation of the final htmldiff
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# * minor changes:
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# ** use symbols instead of string to represent opcodes
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# ** small fix to html2list
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#
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module Enumerable
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def reduce(init)
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result = init
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each { |item| result = yield(result, item) }
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result
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end
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end
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class Object
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def nil_or_empty?
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nil? or empty?
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end
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end
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module Diff
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module Utilities
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def explode(sequence)
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sequence.is_a?(String) ? sequence.split(//) : sequence
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end
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def newline?(char)
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%W(\n \r).include? char
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end
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def tab?(char)
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"\t" == char
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end
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# XXX Could be more robust but unrecognized tags cause an infinite loop so
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# better to be permissive
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def open_tag?(char)
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char =~ /\A<[^>]+>/
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end
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# See comment for open_tag?
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def close_tag?(char)
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char =~ %r!\A</[^>]+>!
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end
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def end_of_tag?(char)
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char == '>'
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end
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def start_of_tag?(char)
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char == '<'
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end
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def html2list(x, use_brackets = false)
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mode = :char
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cur = ''
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out = []
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explode(x).each do |char|
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case mode
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when :tag
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if end_of_tag? char
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cur += use_brackets ? ']' : '>'
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case cur
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when '<pre>' then mode = :pre
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when '<code>' then mode = :code
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else
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out.push cur
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cur, mode = '', :char
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end
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else
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cur += char
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end
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when :char
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if start_of_tag? char
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out.push cur
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cur = use_brackets ? '[' : '<'
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mode = :tag
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elsif /\s/.match char
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out.push cur + char
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cur = ''
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else
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cur += char
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end
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when :pre
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if end_of_tag?(char) and cur =~ %r!</pre$!
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cur += '>'
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out.push cur
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cur, mode = '', :char
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else
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cur += char
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end
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when :code
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if end_of_tag?(char) and cur =~ %r!</code$!
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cur += '>'
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out.push cur
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cur, mode = '', :char
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else
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cur += char
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end
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end
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end
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out.push(cur)
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out.delete ''
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out.map {|elt| newline?(elt) ? elt : elt.chomp}
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end
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end
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class SequenceMatcher
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include Utilities
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def initialize(a = [''], b = [''], isjunk = nil, byline = false)
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a, b = explode(a), explode(b) unless byline
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@isjunk = isjunk || Proc.new {}
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set_sequences a, b
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end
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def set_sequences(a, b)
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set_sequence_a a
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set_sequence_b b
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end
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def set_sequence_a(a)
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@a = a
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@matching_blocks = @opcodes = nil
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end
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def set_sequence_b(b)
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@b = b
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@matching_blocks = @opcodes = nil
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chain_b
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end
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def chain_b
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@fullbcount = nil
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@b2j = {}
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pophash = {}
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junkdict = {}
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@b.each_with_index do |elt, idx|
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if @b2j.has_key? elt
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indices = @b2j[elt]
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if @b.length >= 200 and indices.length * 100 > @b.length
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pophash[elt] = 1
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indices.clear
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else
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indices.push idx
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end
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else
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@b2j[elt] = [idx]
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end
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end
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pophash.each_key { |elt| @b2j.delete elt }
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unless @isjunk.nil?
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[pophash, @b2j].each do |d|
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d.each_key do |elt|
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if @isjunk.call(elt)
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junkdict[elt] = 1
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d.delete elt
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end
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end
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end
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end
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@isbjunk = junkdict.method(:has_key?)
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@isbpopular = junkdict.method(:has_key?)
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end
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def find_longest_match(a_low, a_high, b_low, b_high)
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besti, bestj, bestsize = a_low, b_low, 0
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j2len = {}
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(a_low..a_high).step do |i|
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newj2len = {}
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(@b2j[@a[i]] || []).each do |j|
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next if j < b_low
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break if j >= b_high
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k = newj2len[j] = (j2len[j - 1] || 0) + 1
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if k > bestsize
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besti, bestj, bestsize = i - k + 1, j - k + 1, k
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end
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end
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j2len = newj2len
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end
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while besti > a_low and bestj > b_low and not @isbjunk.call(@b[bestj - 1]) and @a[besti - 1] == @b[bestj - 1]
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besti, bestj, bestsize = besti - 1, bestj - 1, bestsize + 1
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end
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while besti + bestsize < a_high and bestj + bestsize < b_high and
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not @isbjunk.call(@b[bestj + bestsize]) and
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@a[besti + bestsize] == @b[bestj + bestsize]
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bestsize += 1
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end
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while besti > a_low and bestj > b_low and @isbjunk.call(@b[bestj - 1]) and @a[besti - 1] == @b[bestj - 1]
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besti, bestj, bestsize = besti - 1, bestj - 1, bestsize + 1
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end
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while besti + bestsize < a_high and bestj + bestsize < b_high and @isbjunk.call(@b[bestj+bestsize]) and
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@a[besti+bestsize] == @b[bestj+bestsize]
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bestsize += 1
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end
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[besti, bestj, bestsize]
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end
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def get_matching_blocks
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return @matching_blocks unless @matching_blocks.nil_or_empty?
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@matching_blocks = []
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size_of_a, size_of_b = @a.size, @b.size
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match_block_helper(0, size_of_a, 0, size_of_b, @matching_blocks)
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@matching_blocks.push [size_of_a, size_of_b, 0]
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end
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def match_block_helper(a_low, a_high, b_low, b_high, answer)
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i, j, k = x = find_longest_match(a_low, a_high, b_low, b_high)
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unless k.zero?
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match_block_helper(a_low, i, b_low, j, answer) if a_low < i and b_low < j
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answer.push x
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if i + k < a_high and j + k < b_high
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match_block_helper(i + k, a_high, j + k, b_high, answer)
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end
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end
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end
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def get_opcodes
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return @opcodes unless @opcodes.nil_or_empty?
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i = j = 0
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@opcodes = answer = []
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get_matching_blocks.each do |ai, bj, size|
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tag = if i < ai and j < bj
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:replace
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elsif i < ai
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:delete
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elsif j < bj
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:insert
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end
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answer.push [tag, i, ai, j, bj] if tag
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i, j = ai + size, bj + size
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answer.push [:equal, ai, i, bj, j] unless size.zero?
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end
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answer
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end
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# XXX: untested
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def get_grouped_opcodes(n = 3)
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codes = get_opcodes
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if codes.first.first == :equal
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tag, i1, i2, j1, j2 = codes.first
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codes[0] = tag, [i1, i2 - n].max, i2, [j1, j2-n].max, j2
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end
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if codes.last.first == :equal
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tag, i1, i2, j1, j2 = codes.last
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codes[-1] = tag, i1, min(i2, i1+n), j1, min(j2, j1+n)
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end
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nn = n + n
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group = []
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codes.each do |tag, i1, i2, j1, j2|
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if tag == :equal and i2 - i1 > nn
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group.push [tag, i1, [i2, i1 + n].min, j1, [j2, j1 + n].min]
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yield group
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group = []
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i1, j1 = [i1, i2-n].max, [j1, j2-n].max
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group.push [tag, i1, i2, j1 ,j2]
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end
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end
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yield group if group and group.size != 1 and group.first.first == :equal
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end
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def ratio
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matches = get_matching_blocks.reduce(0) do |sum, triple|
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sum + triple.last
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end
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Diff.calculate_ratio(matches, @a.size + @b.size)
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end
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def quick_ratio
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if @fullbcount.nil_or_empty?
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@fullbcount = {}
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@b.each do |elt|
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@fullbcount[elt] = (@fullbcount[elt] || 0) + 1
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end
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end
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avail = {}
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matches = 0
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@a.each do |elt|
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numb = avail.has_key?(elt) ? avail[elt] : (@fullbcount[elt] || 0)
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avail[elt] = numb - 1
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matches += 1 if numb > 0
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end
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Diff.calculate_ratio matches, @a.size + @b.size
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end
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def real_quick_ratio
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size_of_a, size_of_b = @a.size, @b.size
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Diff.calculate_ratio([size_of_a, size_of_b].min, size_of_a + size_of_b)
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end
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protected :chain_b, :match_block_helper
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end # end class SequenceMatcher
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class << self
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def calculate_ratio(matches, length)
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return 1.0 if length.zero?
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2.0 * matches / length
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end
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# XXX: untested
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def get_close_matches(word, possibilities, n = 3, cutoff = 0.6)
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raise "n must be > 0: #{n}" unless n > 0
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raise "cutoff must be in (0.0..1.0): #{cutoff}" unless cutoff.between 0.0..1.0
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result = []
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sequence_matcher = Diff::SequenceMatcher.new
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sequence_matcher.set_sequence_b word
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possibilities.each do |possibility|
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sequence_matcher.set_sequence_a possibility
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if sequence_matcher.real_quick_ratio >= cutoff and
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sequence_matcher.quick_ratio >= cutoff and
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sequence_matcher.ratio >= cutoff
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result.push [sequence_matcher.ratio, possibility]
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end
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end
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unless result.nil_or_empty?
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result.sort
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result.reverse!
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result = result[-n..-1]
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end
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result.map {|score, x| x }
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end
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def count_leading(line, ch)
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count, size = 0, line.size
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count += 1 while count < size and line[count].chr == ch
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count
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end
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end
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end
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module HTMLDiff
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include Diff
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class Builder
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VALID_METHODS = [:replace, :insert, :delete, :equal]
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def initialize(a, b)
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@a, @b = a, b
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@content = []
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end
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def do_op(opcode)
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@opcode = opcode
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op = @opcode.first
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raise NameError, "Invalid opcode '#{op}'" unless VALID_METHODS.include? op
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send op
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end
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def result
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@content.join
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end
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# These methods have to be called via do_op(opcode) so that @opcode is set properly
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private
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def replace
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delete('diffmod')
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insert('diffmod')
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end
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def insert(tagclass = 'diffins')
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op_helper('ins', tagclass, @b[@opcode[3]...@opcode[4]])
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end
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def delete(tagclass = 'diffdel')
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op_helper('del', tagclass, @a[@opcode[1]...@opcode[2]])
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end
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def equal
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@content += @b[@opcode[3]...@opcode[4]]
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end
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# Using this as op_helper would be equivalent to the first version of diff.rb by Bill Atkins
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def op_helper_simple(tagname, tagclass, to_add)
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@content << %(<#{tagname} class="#{tagclass}">) << to_add << %(</#{tagname}>)
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end
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# Tries to put <p> tags or newline chars before the opening diff tags (<ins> or <del>)
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# or after the ending diff tags.
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# As a result the diff tags should be the "most inside" possible.
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def op_helper(tagname, tagclass, to_add)
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predicate_methods = [:tab?, :newline?, :close_tag?, :open_tag?]
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content_to_skip = Proc.new do |item|
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predicate_methods.any? {|predicate| HTMLDiff.send(predicate, item)}
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end
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unless to_add.any? {|element| content_to_skip.call element}
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@content << wrap_text(to_add, tagname, tagclass)
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else
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loop do
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@content << to_add and break if to_add.all? {|element| content_to_skip.call element}
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# We are outside of a diff tag
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@content << to_add.shift while content_to_skip.call to_add.first
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@content << %(<#{tagname} class="#{tagclass}">)
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# We are inside a diff tag
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@content << to_add.shift until content_to_skip.call to_add.first
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@content << %(</#{tagname}>)
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end
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end
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#remove_empty_diff(tagname, tagclass)
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end
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def wrap_text(text, tagname, tagclass)
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%(<#{tagname} class="#{tagclass}">#{text}</#{tagname}>)
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end
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def remove_empty_diff(tagname, tagclass)
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@content = @content[0...-2] if last_elements_empty_diff?(@content, tagname, tagclass)
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end
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def last_elements_empty_diff?(content, tagname, tagclass)
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content[-2] == %(<#{tagname} class="#{tagclass}">) and content.last == %(</#{tagname}>)
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end
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end
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class << self
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include Diff::Utilities
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def diff(a, b)
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a = html2list(explode(a))
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b = html2list(explode(b))
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out = Builder.new(a, b)
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sequence_matcher = Diff::SequenceMatcher.new(a, b)
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sequence_matcher.get_opcodes.each {|opcode| out.do_op(opcode)}
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out.result
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end
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end
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end
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if __FILE__ == $0
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if ARGV.size == 2
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puts HTMLDiff.diff(IO.read(ARGV.pop), IO.read(ARGV.pop))
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else
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puts "Usage: html_diff file1 file2"
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end
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end
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