Merge pull request #41 from korny/speedup

Performance improvements

lib/rouge/lexer.rb

@@ -259,7 +259,7 @@ def option(k, v=:absent)
     # @example
     #   debug { "hello, world!" }
     def debug(&b)
-      puts(b.call) if option :debug
+      puts(b.call) if defined?(@debug) ? @debug : @debug ||= option(:debug)
     end
 
     # @abstract

lib/rouge/regex_lexer.rb

@@ -274,7 +274,7 @@ def scan(scanner, re, &b)
       # StringScanner's implementation of ^ is b0rken.
       # TODO: this doesn't cover cases like /(a|^b)/, but it's
       # the most common, for now...
-      return false if re.source[0] == ?^ && !scanner.beginning_of_line?
+      return false if re.beginning_of_line? && !scanner.beginning_of_line?
 
       @null_steps ||= 0
 
@@ -398,3 +398,17 @@ def with_output_stream(output_stream, &b)
     end
   end
 end
+
+class Regexp
+  # Does this expression start with a ^?
+  # 
+  # Since Regexps are immuntable, this method is cached to avoid
+  # calling Regexp#source more than once.
+  def beginning_of_line?
+    if defined? @beginning_of_line
+      @beginning_of_line
+    else
+      @beginning_of_line = source[0] == ?^
+    end
+  end
+end