Add Velocity lexer (rouge-ruby#1518)

This commit adds a lexer for the Velocity templating language.

lib/rouge/demos/velocity

@@ -0,0 +1,9 @@
+#*
+ There is multi-line comment.
+ see this text because the Velocity Templating Engine will ignore it.
+*#
+<h3>List</h3>
+## This is a single line comment.
+#if( $allProducts )
+<p>not found.</p>
+#end

lib/rouge/lexers/velocity.rb

@@ -0,0 +1,71 @@
+# -*- coding: utf-8 -*- #
+
+module Rouge
+  module Lexers
+    class Velocity < TemplateLexer
+      title 'Velocity'
+      desc 'Velocity is a Java-based template engine (velocity.apache.org)'
+      tag 'velocity'
+      filenames '*.vm', '*.velocity', '*.fhtml'
+      mimetypes 'text/html+velocity'
+
+      id = /[a-z_]\w*/i
+
+      state :root do
+        rule %r/[^{#$]+/ do
+          delegate parent
+        end
+
+        rule %r/(#)(\*.*?\*)(#)/m, Comment::Multiline
+        rule %r/(##)(.*?$)/, Comment::Single
+
+        rule %r/(#\{?)(#{id})(\}?)(\s?\()/m do
+          groups Punctuation, Name::Function, Punctuation, Punctuation
+          push :directive_params
+        end
+
+        rule %r/(#\{?)(#{id})(\}|\b)/m do
+          groups Punctuation, Name::Function, Punctuation
+        end
+
+        rule %r/\$\{?/, Punctuation, :variable
+      end
+
+      state :variable do
+        rule %r/#{id}/, Name::Variable
+        rule %r/\(/, Punctuation, :func_params
+        rule %r/(\.)(#{id})/ do
+          groups Punctuation, Name::Variable
+        end
+        rule %r/\}/, Punctuation, :pop!
+        rule(//) { pop! }
+      end
+
+      state :directive_params do
+        rule %r/(&&|\|\||==?|!=?|[-<>+*%&|^\/])|\b(eq|ne|gt|lt|ge|le|not|in)\b/, Operator
+        rule %r/\[/, Operator, :range_operator
+        rule %r/\b#{id}\b/, Name::Function
+        mixin :func_params
+      end
+
+      state :range_operator do
+        rule %r/[.]{2}/, Operator
+        mixin :func_params
+        rule %r/\]/, Operator, :pop!
+      end
+
+      state :func_params do
+        rule %r/\$\{?/, Punctuation, :variable
+        rule %r/\s+/, Text
+        rule %r/,/, Punctuation
+        rule %r/"(\\\\|\\"|[^"])*"/, Str::Double
+        rule %r/'(\\\\|\\'|[^'])*'/, Str::Single
+        rule %r/0[xX][0-9a-fA-F]+[Ll]?/, Num::Hex
+        rule %r/\b[0-9]+\b/, Num::Integer
+        rule %r/(true|false|null)\b/, Keyword::Constant
+        rule %r/[(\[]/, Punctuation, :push!
+        rule %r/[)\]}]/, Punctuation, :pop!
+      end
+    end
+  end
+end

spec/lexers/velocity_spec.rb

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*- #
+
+describe Rouge::Lexers::Velocity do
+  let(:subject) { Rouge::Lexers::Velocity.new }
+
+  describe 'guessing' do
+    include Support::Guessing
+
+    it 'guesses by filename' do
+      assert_guess :filename => 'foo.velocity'
+      assert_guess :filename => 'foo.vm'
+      assert_guess :filename => 'foo.fhtml'
+    end
+
+    it 'guesses by mimetype' do
+      assert_guess :mimetype => 'text/html+velocity'
+    end
+  end
+end

spec/visual/samples/velocity

@@ -0,0 +1,28 @@
+
+#*
+ There is multi-line comment.
+ see this text because the Velocity Templating Engine will ignore it.
+*#
+<h3>List</h3>
+## This is a single line comment.
+#if( $allProducts )
+<p>not found.</p>
+#else
+
+<table>
+  <tbody>
+    #foreach( $product in $allProducts )
+    <tr id="product-$product.Id" data-url="#SURL("$!product.Slug")">
+      <td>$product.Title</td>
+    </tr>
+    #end
+  </tbody>
+</table>
+#end
+#set( $monkey.Say = ["Not", $my, "fault", 10, false, null] ) ## ArrayList
+${mudSlinger}
+${customer.Address}
+${purchase.getTotal(true)}
+$title.set( "Homage to Catalonia" )
+
+