1 files changed, 98 insertions, 20 deletions

diff --git a/activesupport/lib/active_support/core_ext/hash/keys.rb b/activesupport/lib/active_support/core_ext/hash/keys.rb
index be4d611ce7..8e728691c6 100644
--- a/activesupport/lib/active_support/core_ext/hash/keys.rb
+++ b/activesupport/lib/active_support/core_ext/hash/keys.rb
@@ -1,46 +1,59 @@
 class Hash
-  # Return a new hash with all keys converted to strings.
+  # Return a new hash with all keys converted using the block operation.
   #
-  #   { :name => 'Rob', :years => '28' }.stringify_keys
-  #   #=> { "name" => "Rob", "years" => "28" }
-  def stringify_keys
+  #  hash = { name: 'Rob', age: '28' }
+  #
+  #  hash.transform_keys{ |key| key.to_s.upcase }
+  #  # => { "NAME" => "Rob", "AGE" => "28" }
+  def transform_keys
     result = {}
     keys.each do |key|
-      result[key.to_s] = self[key]
+      result[yield(key)] = self[key]
     end
     result
   end
 
-  # Destructively convert all keys to strings. Same as
-  # +stringify_keys+, but modifies +self+.
-  def stringify_keys!
+  # Destructively convert all keys using the block operations.
+  # Same as transform_keys but modifies +self+
+  def transform_keys!
     keys.each do |key|
-      self[key.to_s] = delete(key)
+      self[yield(key)] = delete(key)
     end
     self
   end
 
+  # Return a new hash with all keys converted to strings.
+  #
+  #   hash = { name: 'Rob', age: '28' }
+  #
+  #   hash.stringify_keys
+  #   #=> { "name" => "Rob", "age" => "28" }
+  def stringify_keys
+    transform_keys{ |key| key.to_s }
+  end
+
+  # Destructively convert all keys to strings. Same as
+  # +stringify_keys+, but modifies +self+.
+  def stringify_keys!
+    transform_keys!{ |key| key.to_s }
+  end
+
   # Return a new hash with all keys converted to symbols, as long as
   # they respond to +to_sym+.
   #
-  #   { 'name' => 'Rob', 'years' => '28' }.symbolize_keys
-  #   #=> { :name => "Rob", :years => "28" }
+  #   hash = { 'name' => 'Rob', 'age' => '28' }
+  #
+  #   hash.symbolize_keys
+  #   #=> { name: "Rob", age: "28" }
   def symbolize_keys
-    result = {}
-    keys.each do |key|
-      result[(key.to_sym rescue key)] = self[key]
-    end
-    result
+    transform_keys{ |key| key.to_sym rescue key }
   end
   alias_method :to_options,  :symbolize_keys
 
   # Destructively convert all keys to symbols, as long as they respond
   # to +to_sym+. Same as +symbolize_keys+, but modifies +self+.
   def symbolize_keys!
-    keys.each do |key|
-      self[(key.to_sym rescue key)] = delete(key)
-    end
-    self
+    transform_keys!{ |key| key.to_sym rescue key }
   end
   alias_method :to_options!, :symbolize_keys!
 
@@ -57,4 +70,69 @@ class Hash
       raise ArgumentError.new("Unknown key: #{k}") unless valid_keys.include?(k)
     end
   end
+
+  # Return a new hash with all keys converted by the block operation.
+  # This includes the keys from the root hash and from all
+  # nested hashes.
+  #
+  #  hash = { person: { name: 'Rob', age: '28' } }
+  #
+  #  hash.deep_transform_keys{ |key| key.to_s.upcase }
+  #  # => { "PERSON" => { "NAME" => "Rob", "AGE" => "28" } }
+  def deep_transform_keys(&block)
+    result = {}
+    each do |key, value|
+      result[yield(key)] = value.is_a?(Hash) ? value.deep_transform_keys(&block) : value
+    end
+    result
+  end
+
+  # Destructively convert all keys by using the block operation.
+  # This includes the keys from the root hash and from all
+  # nested hashes.
+  def deep_transform_keys!(&block)
+    keys.each do |key|
+      value = delete(key)
+      self[yield(key)] = value.is_a?(Hash) ? value.deep_transform_keys!(&block) : value
+    end
+    self
+  end
+
+  # Return a new hash with all keys converted to strings.
+  # This includes the keys from the root hash and from all
+  # nested hashes.
+  #
+  #   hash = { person: { name: 'Rob', age: '28' } }
+  #
+  #   hash.deep_stringify_keys
+  #   # => { "person" => { "name" => "Rob", "age" => "28" } }
+  def deep_stringify_keys
+    deep_transform_keys{ |key| key.to_s }
+  end
+
+  # Destructively convert all keys to strings.
+  # This includes the keys from the root hash and from all
+  # nested hashes.
+  def deep_stringify_keys!
+    deep_transform_keys!{ |key| key.to_s }
+  end
+
+  # Return a new hash with all keys converted to symbols, as long as
+  # they respond to +to_sym+. This includes the keys from the root hash
+  # and from all nested hashes.
+  #
+  #   hash = { 'person' => { 'name' => 'Rob', 'age' => '28' } }
+  #
+  #   hash.deep_symbolize_keys
+  #   # => { person: { name: "Rob", age: "28" } }
+  def deep_symbolize_keys
+    deep_transform_keys{ |key| key.to_sym rescue key }
+  end
+
+  # Destructively convert all keys to symbols, as long as they respond
+  # to +to_sym+. This includes the keys from the root hash and from all
+  # nested hashes.
+  def deep_symbolize_keys!
+    deep_transform_keys!{ |key| key.to_sym rescue key }
+  end
 end