Recognize javascript functions & classes (#1920)

* Recognize javascript functions

With this change, javascript functions will be recognized both when they
are defined and when they are called.

* Fix failing test

With the update to the javascript lexer, functions are now recognized.
This updates the test case to reflect this.

* Add function name token to regex to avoid adding state

* Support Unicode character function names

* Correctly recognize an anonymous function

* Recognize javascript classes

In order to recognize classes we have to tweak the `id` regex because we
want to try to differentiate between functions and classes. To recognize
classes, the first letter that appears in the name must not be a
lowercase character.

* Added javascript visual samples

Added for the new function and class (with unicode support) recognition.

* Add support for javascript class inheritance

Author: dunkmann00

lib/rouge/lexers/javascript.rb

@@ -177,6 +177,21 @@ def self.id_regex
           push :expr_start
         end
 
+        rule %r/(class)((?:\s|\\\s)+)/ do
+          groups Keyword::Declaration, Text
+          push :classname
+        end
+
+        rule %r/([\p{Nl}$_]*\p{Lu}[\p{Word}]*)[ \t]*(?=(\(.*\)))/m, Name::Class
+
+        rule %r/(function)((?:\s|\\\s)+)(#{id})/ do
+          groups Keyword::Declaration, Text, Name::Function
+        end
+
+        rule %r/function(?=(\(.*\)))/, Keyword::Declaration # For anonymous functions
+
+        rule %r/(#{id})[ \t]*(?=(\(.*\)))/m, Name::Function
+
         rule %r/[{}]/, Punctuation, :statement
 
         rule id do |m|
@@ -220,6 +235,14 @@ def self.id_regex
         rule %r/'/, Str::Delimiter, :pop!
       end
 
+      state :classname do
+        rule %r/(#{id})((?:\s|\\\s)+)(extends)((?:\s|\\\s)+)/ do
+          groups Name::Class, Text, Keyword::Declaration, Text
+        end
+
+        rule id, Name::Class, :pop!
+      end
+
       # braced parts that aren't object literals
       state :statement do
         rule %r/case\b/ do

spec/formatters/html_spec.rb

@@ -39,7 +39,7 @@ class InlineTheme < Rouge::CSSTheme
 
     it 'should format token stream' do
       assert { output == '<span class="nt">&lt;meta</span> <span class="na">name=</span><span class="s">"description"</span> <span class="na">content=</span><span class="s">"foo"</span><span class="nt">&gt;</span>
-<span class="nt">&lt;script&gt;</span><span class="nx">alert</span><span class="p">(</span><span class="dl">"</span><span class="s2">bar</span><span class="dl">"</span><span class="p">)</span><span class="nt">&lt;/script&gt;</span>' }
+<span class="nt">&lt;script&gt;</span><span class="nf">alert</span><span class="p">(</span><span class="dl">"</span><span class="s2">bar</span><span class="dl">"</span><span class="p">)</span><span class="nt">&lt;/script&gt;</span>' }
     end
   end
 

spec/visual/samples/javascript

@@ -148,6 +148,9 @@ Blag.ReadMore = (function($) {
   $(document).ready(init);
 })(jQuery);
 
+underscoreFunc = _underscoreFunc()
+underscoreClass = _UnderscoreClass()
+
 // evil regexes, from pygments
 
 /regexp/.test(foo) || x = [/regexp/,/regexp/, /regexp/, // comment
@@ -283,6 +286,8 @@ class Œuvre {
   }
 }
 
+unicodeClass = Œuvre()
+
 // Nullish coalescing operator (??)
 let ret = "";
 let foo, bar;