A pure-Ruby implementation VCDIFF encoder/decoder. Aims to provide similar functionality to Google's open-vcdiff (which the vcdiff gem wraps), but without the C.

Some important notes and to-be-implemented things:

• Encoding isn't implemented yet, although the plan is to use the bentley_mcilroy gem, following the same strategy as open-vcdiff. There is a question of what block size to use for windows when finding common substrings.
• The decoder can't handle custom code tables or any sort of compression flags. Compression is probably a won't-fix on account of there being no compressor ID standards and the RFC for VCDIFF doesn't specify one. Custom code table support is desirable so every VCDIFF encoding is supported when decoding.
• The decoder doesn't handle any window where the VCD_TARGET bit is set in the window indicator (Win_indicator). As with custom code tables, it would be good to have this. It's currently omitted for simplicity.

Further reading:

• RFC3284 — The VCDIFF Generic Differencing and Compression Data Format

Add this line to your application's Gemfile:

gem "vcdiff.rb"

And then execute:

$ bundle install

Or install it yourself as:

$ gem install vcdiff.rb

Not yet implemented.

decoder = VCDIFF::Decoder.new("path/to/dictionary_source")
original_target = decoder.decode("path/to/delta_file")

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

The issue tracker is on GitHub. If you find any bugs, just open an issue.

Copyright (c) Adam Prescott, released under the MIT license. See the license file.