67 lines
2.1 KiB
Ruby
67 lines
2.1 KiB
Ruby
# Builds an HTML diff between two pieces of text.
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class DiffBuilder
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attr_reader :this_text, :that_text, :pattern
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def initialize(this_text, that_text, pattern)
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@this_text = this_text
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@that_text = that_text
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@pattern = pattern
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end
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def build
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thisarr = this_text.scan(pattern)
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otharr = that_text.scan(pattern)
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cbo = Diff::LCS::ContextDiffCallbacks.new
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diffs = otharr.diff(thisarr, cbo)
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escape_html = ->(str) {str.gsub(/&/, '&').gsub(/</, '<').gsub(/>/, '>')}
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output = otharr
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output.each { |q| q.replace(escape_html[q]) }
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diffs.reverse_each do |hunk|
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old_cr = hunk[0].try(:old_element)
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new_cr = hunk[1].try(:new_element)
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if old_cr && new_cr && old_cr.match?(/^\r?\n$/) && new_cr.match?(/^\r?\n$/)
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hunk_position = hunk[0].old_position
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output[hunk_position] = '<del><span class="paragraph-mark">¶</span></del><ins><span class="paragraph-mark">¶</span></ins><br>'
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next
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end
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newchange = hunk.max {|a, b| a.old_position <=> b.old_position}
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newstart = newchange.old_position
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oldstart = hunk.min {|a, b| a.old_position <=> b.old_position}.old_position
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if newchange.action == '+'
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output.insert(newstart, '</ins>')
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end
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hunk.reverse_each do |chg|
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case chg.action
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when '-'
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oldstart = chg.old_position
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output[chg.old_position] = '<span class="paragraph-mark">¶</span><br>' if chg.old_element.match(/^\r?\n$/)
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when '+'
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if chg.new_element.match(/^\r?\n$/)
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output.insert(chg.old_position, '<span class="paragraph-mark">¶</span><br>')
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else
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output.insert(chg.old_position, (escape_html[chg.new_element]).to_s)
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end
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end
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end
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if newchange.action == '+'
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output.insert(newstart, '<ins>')
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end
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if hunk[0].action == '-'
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output.insert((newstart == oldstart || newchange.action != '+') ? newstart + 1 : newstart, '</del>')
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output.insert(oldstart, '<del>')
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end
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end
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output.join.gsub(/\r?\n/, '<span class="paragraph-mark">¶</span><br>').html_safe
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end
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end
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