A Ruby implementation of the Myers diff algorithm.

Basically a minimal and incomplete port of the jsdiff Javascript library.

Links

• Algorithm paper: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.4.6927
• Reference JS implementation: https://github.com/kpdecker/jsdiff

Usage

You can use MyersDiff::CharDiff#diff(s1, s2) to calculate an edit script that changes a string s1 into s2. The return value is an edit script, represented as an array of edit commands. The edit commands are hashes that are formatted in three ways:

1. Match: { count: <integer>, value: <string> }
2. Add: { count: <integer>, added: true, value: <string> }
3. Remove: { count: <integer>, removed: true, value: <string> }

diff = MyersDiff::CharDiff.new
diff.diff('abcabba', 'cbabac')

 => [{:count=>1, :added=>nil, :removed=>true, :value=>"a"}, {:count=>1, :added=>true, :removed=>nil, :value=>"c"}, {:count=>1, :value=>"b"}, {:count=>1, :added=>nil, :removed=>true, :value=>"c"}, {:count=>2, :value=>"ab"}, {:count=>1, :added=>nil, :removed=>true, :value=>"b"}, {:count=>1, :value=>"a"}, {:count=>1, :added=>true, :removed=>nil, :value=>"c"}]

License

MIT

Releasing

• Update version file
• Run bundle install
• Commit changes
• Add tag git tag -s vVERSION
• git push && git push --tags
• gem build myers_diff.gemspec
• gem push myers_diff-VERSION.gemspec