diffy

On Unix

Install the gem directly using rubygems:

gem install diffy

On Windows

1. Ensure you have a working diff command in your system PATH. Options include:
   • Installing Diff::LCS (includes ldiff).
   • Using RubyInstaller with the devkit installed.
   • Installing unxutils (note: uses diff 2.7, which may cause whitespace handling differences).
   • Installing gnuwin32 components individually (note: delivers diff 2.8, which is recommended for compatibility).
2. Install the gem:

gem install diffy

To generate HTML, pass :html or :html_simple to the to_s method. For character-level highlighting, use :html.

Diffy provides CSS for styling these outputs via Diffy::CSS. A colorblind-safe palette is available in Diffy::CSS_COLORBLIND_1.

puts Diffy::Diff.new("foo\n", "Foo\n").to_s(:html)
puts Diffy::CSS

Diffy::Diff implements the Enumerable interface, allowing you to iterate over the resulting lines or groups of changes.

• #each: Iterates over every line in the diff. Lines starting with +, -, or indicate additions, deletions, or unchanged lines respectively.
• #each_chunk: Iterates over groupings of additions, deletions, and unchanged lines.

Diffy::Diff.new("foo\nbar\n", "foo\nbar\nbaz\n").each do |line|
  case line
  when /^\+/ then puts "line #{line.chomp} added"
  when /^-/ then puts "line #{line.chomp} removed"
  end
end

Diffy::Diff.new("foo\nbar\nbang\nbaz\n", "foo\nbar\nbing\nbong\n").each_chunk.to_a

To compare the contents of two files rather than treating the arguments as raw strings, pass the :source => 'files' option.

puts Diffy::Diff.new('/tmp/foo', '/tmp/bar', :source => 'files')

Use the Diffy::SplitDiff class to create a split view where deletions are on the left and insertions are on the right. Unlike Diffy::Diff, you use #left and #right methods to retrieve the sides.

Usage: Diffy::SplitDiff.new(string1, string2, options = {})

Options like :format can be passed to change the output of the split sides.

Diffy::SplitDiff.new(string1, string2, :format => :html).left
Diffy::SplitDiff.new(string1, string2, :format => :html).right

You can specify the output format by passing a symbol to Diffy::Diff#to_s. You can also set a global default format using Diffy::Diff.default_format = :format.

Supported Formats:

• :text - Plain text output.
• :color - ANSI colorized text for terminals.
• :html - HTML output with inline character-level highlighting (GitHub-style).
• :html_simple - HTML output without inline highlighting (better for performance or simplicity).

Diffy::Diff.default_format = :html

The Diffy::SplitDiff class allows you to generate a diff and then split it into two distinct parts: the 'left' side (original/deletions) and the 'right' side (new/additions). This is useful for creating side-by-side comparison views.

To use SplitDiff, initialize it with the left string, the right string, and an optional options hash. You must specify a valid :format in the options (e.g., :color, :html, :html_simple, or :text).

Once initialized, you can call .left and .right to retrieve the respective components.