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Régis Hanol
265
lib/discourse_diff.rb
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265
lib/discourse_diff.rb
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require_dependency "onpdiff"
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class DiscourseDiff
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MAX_DIFFERENCE = 200
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def initialize(before, after)
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@before = before
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@after = after
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@block_by_block_diff = ONPDiff.new(tokenize_html_blocks(@before), tokenize_html_blocks(@after)).diff
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@line_by_line_diff = ONPDiff.new(tokenize_line(@before), tokenize_line(@after)).short_diff
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end
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def inline_html
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i = 0
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inline = []
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while i < @block_by_block_diff.length
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op_code = @block_by_block_diff[i][1]
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if op_code == :common then inline << @block_by_block_diff[i][0]
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else
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if op_code == :delete
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opposite_op_code = :add
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klass = "del"
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first = i
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second = i + 1
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else
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opposite_op_code = :delete
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klass = "ins"
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first = i + 1
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second = i
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end
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if i + 1 < @block_by_block_diff.length && @block_by_block_diff[i + 1][1] == opposite_op_code
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diff = ONPDiff.new(tokenize_html(@block_by_block_diff[first][0]), tokenize_html(@block_by_block_diff[second][0])).diff
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inline << generate_inline_html(diff)
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i += 1
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else
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inline << add_class_or_wrap_in_tags(@block_by_block_diff[i][0], klass)
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end
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end
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i += 1
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end
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"<div class=\"inline-diff\">#{inline.join}</div>"
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end
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def side_by_side_html
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i = 0
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left, right = [], []
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while i < @block_by_block_diff.length
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op_code = @block_by_block_diff[i][1]
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if op_code == :common
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left << @block_by_block_diff[i][0]
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right << @block_by_block_diff[i][0]
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else
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if op_code == :delete
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opposite_op_code = :add
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side = left
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klass = "del"
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first = i
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second = i + 1
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else
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opposite_op_code = :delete
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side = right
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klass = "ins"
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first = i + 1
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second = i
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end
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if i + 1 < @block_by_block_diff.length && @block_by_block_diff[i + 1][1] == opposite_op_code
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diff = ONPDiff.new(tokenize_html(@block_by_block_diff[first][0]), tokenize_html(@block_by_block_diff[second][0])).diff
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deleted, inserted = generate_side_by_side_html(diff)
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left << deleted
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right << inserted
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i += 1
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else
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side << add_class_or_wrap_in_tags(@block_by_block_diff[i][0], klass)
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end
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end
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i += 1
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end
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"<div class=\"span8\">#{left.join}</div><div class=\"span8 offset1\">#{right.join}</div>"
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end
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def side_by_side_text
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i = 0
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table = ["<table class=\"markdown\">"]
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while i < @line_by_line_diff.length
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table << "<tr>"
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op_code = @line_by_line_diff[i][1]
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if op_code == :common
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table << "<td>#{CGI::escapeHTML(@line_by_line_diff[i][0])}</td>"
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table << "<td>#{CGI::escapeHTML(@line_by_line_diff[i][0])}</td>"
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else
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if op_code == :delete
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opposite_op_code = :add
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first = i
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second = i + 1
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else
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opposite_op_code = :delete
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first = i + 1
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second = i
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end
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if i + 1 < @line_by_line_diff.length && @line_by_line_diff[i + 1][1] == opposite_op_code
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before_tokens, after_tokens = tokenize_text(@line_by_line_diff[first][0]), tokenize_text(@line_by_line_diff[second][0])
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if (before_tokens.length - after_tokens.length).abs > MAX_DIFFERENCE
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before_tokens, after_tokens = tokenize_line(@line_by_line_diff[first][0]), tokenize_line(@line_by_line_diff[second][0])
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end
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diff = ONPDiff.new(before_tokens, after_tokens).short_diff
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deleted, inserted = generate_side_by_side_text(diff)
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table << "<td class=\"diff-del\">#{deleted.join}</td>"
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table << "<td class=\"diff-ins\">#{inserted.join}</td>"
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i += 1
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else
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if op_code == :delete
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table << "<td class=\"diff-del\">#{CGI::escapeHTML(@line_by_line_diff[i][0])}</td>"
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table << "<td></td>"
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else
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table << "<td></td>"
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table << "<td class=\"diff-ins\">#{CGI::escapeHTML(@line_by_line_diff[i][0])}</td>"
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end
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end
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end
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table << "</tr>"
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i += 1
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end
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table << "</table>"
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table.join
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end
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private
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def tokenize_line(text)
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text.scan(/[^\r\n]+[\r\n]*/)
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end
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def tokenize_text(text)
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t, tokens = [], []
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i = 0
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while i < text.length
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if text[i] =~ /\w/
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t << text[i]
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elsif text[i] =~ /[ \t]/ && t.join =~ /^\w+$/
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begin
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t << text[i]
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i += 1
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end while i < text.length && text[i] =~ /[ \t]/
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i -= 1
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tokens << t.join
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t = []
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else
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tokens << t.join if t.length > 0
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tokens << text[i]
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t = []
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end
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i += 1
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end
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tokens << t.join if t.length > 0
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tokens
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end
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def tokenize_html_blocks(html)
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Nokogiri::HTML.fragment(html).search("./*").map(&:to_html)
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end
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def tokenize_html(html)
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HtmlTokenizer.tokenize(html)
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end
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def add_class_or_wrap_in_tags(html_or_text, klass)
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index_of_next_chevron = html_or_text.index(">")
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if html_or_text.length > 0 && html_or_text[0] == '<' && index_of_next_chevron
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index_of_class = html_or_text.index("class=")
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if index_of_class.nil? || index_of_class > index_of_next_chevron
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# we do not have a class for the current tag
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# add it right before the ">"
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html_or_text.insert(index_of_next_chevron, " class=\"diff-#{klass}\"")
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else
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# we have a class, insert it at the beginning
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html_or_text.insert(index_of_class + "class=".length + 1, "diff-#{klass} ")
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end
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else
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"<#{klass}>#{html_or_text}</#{klass}>"
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end
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end
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def generate_inline_html(diff)
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inline = []
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diff.each do |d|
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case d[1]
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when :common then inline << d[0]
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when :delete then inline << add_class_or_wrap_in_tags(d[0], "del")
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when :add then inline << add_class_or_wrap_in_tags(d[0], "ins")
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end
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end
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inline
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end
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def generate_side_by_side_html(diff)
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deleted, inserted = [], []
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diff.each do |d|
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case d[1]
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when :common
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deleted << d[0]
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inserted << d[0]
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when :delete then deleted << add_class_or_wrap_in_tags(d[0], "del")
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when :add then inserted << add_class_or_wrap_in_tags(d[0], "ins")
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end
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end
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[deleted, inserted]
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end
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def generate_side_by_side_text(diff)
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deleted, inserted = [], []
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diff.each do |d|
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case d[1]
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when :common
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deleted << d[0]
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inserted << d[0]
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when :delete then deleted << "<del>#{CGI::escapeHTML(d[0])}</del>"
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when :add then inserted << "<ins>#{CGI::escapeHTML(d[0])}</ins>"
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end
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end
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[deleted, inserted]
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end
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class HtmlTokenizer < Nokogiri::XML::SAX::Document
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attr_accessor :tokens
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def initialize
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@tokens = []
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end
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def self.tokenize(html)
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me = new
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parser = Nokogiri::HTML::SAX::Parser.new(me)
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parser.parse("<html><body>#{html}</body></html>")
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me.tokens
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end
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USELESS_TAGS = %w{html body}
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def start_element(name, attributes = [])
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return if USELESS_TAGS.include?(name)
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attrs = attributes.map { |a| " #{a[0]}=\"#{a[1]}\"" }.join
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@tokens << "<#{name}#{attrs}>"
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end
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AUTOCLOSING_TAGS = %w{area base br col embed hr img input meta}
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def end_element(name)
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return if USELESS_TAGS.include?(name) || AUTOCLOSING_TAGS.include?(name)
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@tokens << "</#{name}>"
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end
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def characters(string)
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@tokens.concat string.scan(/(\W|\w+[ \t]*)/).flatten
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end
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end
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end
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