1 files changed, 25 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/regexp.rb b/activesupport/lib/active_support/core_ext/regexp.rb
new file mode 100644
index 0000000000..1a04c70d87
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/regexp.rb
@@ -0,0 +1,25 @@
+class Regexp #:nodoc:
+  def number_of_captures
+    Regexp.new("|#{source}").match('').captures.length
+  end
+
+  def multiline?
+    options & MULTILINE == MULTILINE
+  end
+
+  class << self
+    def optionalize(pattern)
+      case unoptionalize(pattern)
+        when /\A(.|\(.*\))\Z/ then "#{pattern}?"
+        else "(?:#{pattern})?"
+      end
+    end
+
+    def unoptionalize(pattern)
+      [/\A\(\?:(.*)\)\?\Z/, /\A(.|\(.*\))\?\Z/].each do |regexp|
+        return $1 if regexp =~ pattern
+      end
+      return pattern
+    end
+  end
+end