add a diff lexer

lib/rouge.rb

@@ -16,6 +16,7 @@ def highlight(text, lexer, formatter)
 load load_dir.join('rouge/token.rb')
 load load_dir.join('rouge/lexer.rb')
 load load_dir.join('rouge/lexers/text.rb')
+load load_dir.join('rouge/lexers/diff.rb')
 load load_dir.join('rouge/lexers/shell.rb')
 load load_dir.join('rouge/lexers/javascript.rb')
 

lib/rouge/lexers/diff.rb

@@ -0,0 +1,27 @@
+module Rouge
+  module Lexers
+    class Diff < RegexLexer
+      tag 'diff'
+      aliases 'patch'
+
+      state :header do
+        rule /^diff .*?\n(?=---|\+\+\+)/m, 'Generic.Heading'
+        rule /^--- .*?\n/, 'Generic.Deleted'
+        rule /^\+\+\+ .*?\n/, 'Generic.Inserted'
+      end
+
+      state :diff do
+        rule /@@ -\d+,\d+ \+\d+,\d+ @@.*?\n/, 'Generic.Heading'
+        rule /^\+.*?\n/, 'Generic.Inserted'
+        rule /^-.*?\n/,  'Generic.Deleted'
+        rule /^ .*?\n/,  'Text'
+        rule /^.*?\n/,   'Error'
+      end
+
+      state :root do
+        mixin :header
+        mixin :diff
+      end
+    end
+  end
+end

spec/visual/samples/diff

@@ -0,0 +1,55 @@
+diff --git a/README.md b/README.md
+index 87f10f4..09ba8c0 100644
+--- a/README.md
++++ b/README.md
+@@ -1,10 +1,23 @@
+ # Rouge
+
+-This project is not yet finished, but this works:
++This project needs your help!  There are lots of lexers to be implemented / ported / fixed, and features that need to be added or implemented.  If you'd like to help out, send me a pull request (even if it's not done yet!).  Bonus points for feature branches.
++
++## Usage
+
+ ``` ruby
+-formatter = Rouge::Formatters::HTML.new
++# make some nice lexed html, compatible with pygments stylesheets
++formatter = Rouge::Formatters::HTML.new(:css_class => '.highlight')
+ Rouge.highlight(File.read('/etc/bash.bashrc'), 'shell', formatter)
++
++# apply a theme
++Rouge::Themes::ThankfulEyes.new(:scope => '.highlight').render
+ ```
+
+-More features, documentation, lexers, and formatters to come.  Help is appreciated, too, if you think this is awesome :)
++Rouge aims to be simple to extend, and to be a drop-in replacement pygments, with the same quality of output.
++
++### Advantages to pygments.rb
++* No python bridge is necessary - you can deploy it on Heroku effortlessly, without the need for [epic hacks][].
++
++### Advantages to CodeRay
++
++[epic hacks]: https://github.com/rumblelabs/pygments-heroku
+diff --git a/lib/rouge.rb b/lib/rouge.rb
+index e86da00..c947a8b 100644
+--- a/lib/rouge.rb
++++ b/lib/rouge.rb
+@@ -16,6 +16,7 @@ load_dir = Pathname.new(__FILE__).dirname
+ load load_dir.join('rouge/token.rb')
+ load load_dir.join('rouge/lexer.rb')
+ load load_dir.join('rouge/lexers/text.rb')
++load load_dir.join('rouge/lexers/diff.rb')
+ load load_dir.join('rouge/lexers/shell.rb')
+ load load_dir.join('rouge/lexers/javascript.rb')
+
+diff --git a/lib/rouge/token.rb b/lib/rouge/token.rb
+index ab1701b..155fa52 100644
+--- a/lib/rouge/token.rb
++++ b/lib/rouge/token.rb
+@@ -112,6 +112,7 @@ module Rouge
+     token 'Keyword.Type',                'kt'
+
+     token 'Name',                        'n'
++
+     token 'Name.Attribute',              'na'
+     token 'Name.Builtin',                'nb'
+     token 'Name.Builtin.Pseudo',         'bp'