Rblines

Rblines is a Ruby clone of the Redlines Python package. It produces a Markdown text showing the differences between two strings/text. The changes are represented with strike-throughs and underlines, which looks similar to Microsoft Word's track changes. This method of showing changes is more familiar to lawyers and is more compact for long series of characters.

Given an original string:

The quick brown fox jumps over the lazy dog.

And the string to be tested with:

The quick brown fox walks past the lazy dog.

The library gives a result of:

The quick brown fox <del>jumps over </del><ins>walks past </ins>the lazy dog.

Which is rendered like this:

The quick brown fox jumps over walks past the lazy dog.

Install the gem and add to the application's Gemfile by executing:

$ bundle add rblines

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install rblines

The library contains one class: Rblines::Redlines, which is used to compare text.

test = Rblines::Redlines.new(
    "The quick brown fox jumps over the lazy dog.",
    "The quick brown fox walks past the lazy dog.",
    markdown_style: "none"
)
test.output_markdown == "The quick brown fox <del>jumps over </del><ins>walks past </ins>the lazy dog."
# => True

Alternatively, you can create Redline with the text to be tested, and compare several times to see the results.

test = Rblines::Redlines.new("The quick brown fox jumps over the lazy dog.", markdown_style: "none")
test.compare("The quick brown fox walks past the lazy dog.") == "The quick brown fox <del>jumps over </del><ins>walks past </ins>the lazy dog."
# => True

test.compare("The quick brown fox jumps over the dog.") == "The quick brown fox jumps over the <del>lazy </del>dog."
# => True

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

The original Redlines uses the SequenceMatcher from difflib. This handles the diff a bit different from the gem diff-lcs that we are using in this project. So in the spec handles different number of paragraphs correctly we changed the expected output a bit:

# changed the expected output from:
expected_md = "Happy Saturday, \n\nThank you for reaching <del>out, have </del><ins>out. Have </ins>a good <del>weekend \n\nBest, ¶ Sophia</del><ins>weekend. \n\nSophia.</ins>"
# to:
expected_md = "Happy Saturday, \n\nThank you for reaching <del>out, have </del><ins>out. Have </ins>a good <del>weekend </del><ins>weekend. </ins>\n\n<del>Best, </del><ins>Sophia.</ins><del>¶ Sophia</del>"

We think that the Redlines output is better, but until we find a better way to handle this, we will keep the current output, that is also not that bad.

Bug reports and pull requests are welcome on GitHub at https://github.com/kdiogenes/rblines.

The gem is available as open source under the terms of the MIT License.