discourse/lib/diff_engine.rb

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require 'diffy'
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# This class is used to generate diffs, it will be consumed by the UI on
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# on the client the displays diffs.
#
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# There are potential performance issues associated with diffing large amounts of completely
# different text, see answer here for optimization if needed
# http://meta.stackoverflow.com/questions/127497/suggested-edit-diff-shows-different-results-depending-upon-mode
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class DiffEngine
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# generate an html friendly diff similar to the way Stack Exchange generates
# html diffs
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#
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# returns: html containing decorations indicating the changes
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def self.html_diff(html_before, html_after)
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Diffy::Diff.new(html_before, html_after).to_s(:html)
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end
# same as html diff, except that it operates on markdown
#
# returns html containing decorated areas where diff happened
def self.markdown_diff(markdown_before, markdown_after)
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Diffy::Diff.new(markdown_before, markdown_after).to_s(:html)
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end
end