Diffy - Easy Diffing With Ruby
Need diffs in your ruby app? Diffy has you covered. It provides a convenient way to generate a diff from two strings. Instead of reimplementing the LCS diff algorithm Diffy uses battle tested Unix diff to generate diffs, and focuses on providing a convenient interface, and getting out of your way.
Supported Formats
It provides several built in format options which can be passed to
Diffy::Diff#to_s
.
:text
- Plain text output:color
- ANSI colorized text suitable for use in a terminal:html
- HTML output. Since version 2.0 this format does inline highlighting of the changes between two the changes within lines.:html_simple
- HTML output without inline highlighting. This may be useful in situations where high performance is required or simpler output is desired.
A default format can be set like so:
Diffy::Diff.default_format = :html
Getting Started
sudo gem install diffy
Here's an example of using Diffy to diff two strings
$ irb
>> string1 = <<-TXT
>" Hello how are you
>" I'm fine
>" That's great
>" TXT
=> "Hello how are you\nI'm fine\nThat's great\n"
>> string2 = <<-TXT
>" Hello how are you?
>" I'm fine
>" That's swell
>" TXT
=> "Hello how are you?\nI'm fine\nThat's swell\n"
>> puts Diffy::Diff.new(string1, string2)
-Hello how are you
+Hello how are you?
I'm fine
-That's great
+That's swell
Outputing the diff as html is easy too.
>> puts Diffy::Diff.new(string1, string2).to_s(:html_simple)
<div class="diff">
<ul>
<li class="del"><del>Hello how are you</del></li>
<li class="ins"><ins>Hello how are you?</ins></li>
<li class="unchanged"><span>I'm fine</span></li>
<li class="del"><del>That's great</del></li>
<li class="ins"><ins>That's swell</ins></li>
</ul>
</div>
Then try adding this css to your stylesheets:
.diff{overflow:auto;}
.diff ul{background:#fff;overflow:auto;font-size:13px;list-style:none;margin:0;padding:0;display:table;width:100%;}
.diff del, .diff ins{display:block;text-decoration:none;}
.diff li{padding:0; display:table-row;margin: 0;}
/* try 'whitespace:pre;' if you don't want lines to wrap */
.diff del, .diff ins, .diff span{white-space:pre-wrap;font-family:courier;}
.diff li.ins{background:#9f9;}
.diff li.del{background:#fcc;}
.diff li.ins strong{font-weight:normal; background: #6f6 }
.diff li.del strong{font-weight:normal; background: #f99 }
You can also diff files instead of strings
>> puts Diffy::Diff.new('/tmp/foo', '/tmp/bar', :source => 'files')
Custom Formats
Diffy tries to make generating your own custom formatted output easy.
Diffy::Diff
provides an enumberable interface which lets you iterate over
lines in the diff.
>> 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
line +baz added
=> [" foo\n", " bar\n", "+baz\n"]
You can also use Diffy::Diff#each_chunk
to iterate each grouping of additions,
deletions, and unchanged in a diff.
>> Diffy::Diff.new("foo\nbar\nbang\nbaz\n", "foo\nbar\nbing\nbong\n").each_chunk.to_a
=> [" foo\n bar\n", "-bang\n-baz\n", "+bing\n+bong\n"]
Use #map
, #inject
, or any of Enumerable's methods. Go crazy.
Ruby Version Compatibility
Support for Ruby 1.8.6 was dropped beggining at version 2.0 in order to support the chainable enumerators available in 1.8.7 and 1.9.
If you want to use Diffy and Ruby 1.8.6 then:
$ gem install diffy -v1.1.0
Report bugs or request features at http://github.com/samg/diffy/issues