This simple Ruby class is a formatter extension for pvande’s excellent “differ” gem. The built-in HTML formatter is great for line-by-line diffs or word-by-word diffs but cannot generate output that shows both line changes and, within a line change, highlights word changes (as seen on Trac and github, for example). This formatter will generate the HTML tags necessary to produce such output.
The author(s) of the differ gem had the foresight to allow classes to be passed to the “format_as” method. Simply copy nested_html.rb to a suitable directory in your project, require it as needed and then pass the class to format_as:
Differ.diff( @current, @original ).format_as( Differ::Format::NestedHTML )
The resulting output will look something like this:
Now is the time <del class="differ">for all good <del class="differ_inner">men</del></del> <ins class="differ">for all good <ins class="differ_inner">people</ins></ins> to come to the aid of their countries.
Use your own stylesheets to apply whatever formatting you like. I use something like this:
.revision_diff del.differ {display:block;text-decoration:none;background-color:#dfd;color:#333;margin:3px -5px;padding:3px 5px}
.revision_diff ins.differ {display:block;text-decoration:none;background-color:#fdd;color:#333;margin:3px -5px;padding:3px 5px}
.revision_diff del.differ_inner {display:inline;text-decoration:none;background-color:#9e9;color:#333;margin:1px;}
.revision_diff ins.differ_inner {display:inline;text-decoration:none;background-color:#e99;color:#333;margin:1px;}
Distributed under the University of Illinois/NCSA Open Source License - see License.txt for details.