Diff Longest Common Sub String

"The diff sniffing out texts every move"

A resonably fast diff algoritm using longest common substrings that can also detect text that has moved.

First require it.

$ irb

require 'rubygems' require 'difflcs'

Then it can be used on any set of arrays, in this example 123456789 and 120678934, of which the first '12' overlaps, '0' is new, '34' has moved to the end, and '6789' overlaps too, but moved 2 positions to the left.

NOTE: They are arrays, not strings.

DiffLCS.diff('123456789'.split(''), '120678934'.split('')) => { :matched_old=>[0...2, 5...9, 2...4], :matched_new=>[0...2, 3...7, 7...9] }

As you see it can sniff out text that has moved too.

A minimum overlap size can be provided for speed purposes, and to prevent too many matches;

DiffLCS.diff('123456789'.split(''), '120678934'.split(''), :minimum_lcs_size => 3) => { :matched_old => PositionRange::List.from_s('5,9'), :matched_new => PositionRange::List.from_s('3,7') }

Diff can be called directly on strings too, if 'diff_l_c_s/string' is required.

require 'diff_l_c_s/string' '123'.diff('321') => { :matched_old=>[2...3, 1...2, 0...1], :matched_new=>[0...1, 1...2, 2...3] }

Add this line to your application's Gemfile:

gem 'difflcs'

And then execute:

$ bundle

Or install it yourself as:

$ gem install difflcs

Feel free to report issues and to ask questions. For the latest news on DiffLCS:

• http://foundation.logilogi.org/tags/DiffLCS

If you wish to contribute, please create a pull-request and remember to update the corresponding unit test(s).

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request