1 files changed, 36 insertions, 0 deletions
diff --git a/activesupport/lib/core_ext/hash/keys.rb b/activesupport/lib/core_ext/hash/keys.rb
new file mode 100644
index 0000000000..0db37a6374
--- /dev/null
+++ b/activesupport/lib/core_ext/hash/keys.rb
@@ -0,0 +1,36 @@
+module ActiveSupport
+  module CoreExtensions
+    module Hash
+      module Keys
+
+        # Return a new hash with all keys converted to symbols.
+        def symbolize_keys
+          inject({}) do |options, (key, value)|
+            options[key.to_sym] = value
+            options
+          end
+        end
+
+        # Destructively convert all keys to symbols.
+        def symbolize_keys!
+          keys.each do |key|
+            unless key.is_a?(Symbol)
+              self[key.to_sym] = self[key]
+              delete(key)
+            end
+          end
+          self
+        end
+
+        alias_method :to_options,  :symbolize_keys
+        alias_method :to_options!, :symbolize_keys!
+
+        def assert_valid_keys(valid_keys)
+          unknown_keys = keys - valid_keys
+          raise(ArgumentError, "Unknown key(s): #{unknown_keys.join(", ")}") unless unknown_keys.empty?
+        end
+
+      end
+    end
+  end
+end