1 files changed, 92 insertions, 19 deletions

diff --git a/activesupport/lib/active_support/core_ext/hash/keys.rb b/activesupport/lib/active_support/core_ext/hash/keys.rb
index d8748b1138..362d584ba1 100644
--- a/activesupport/lib/active_support/core_ext/hash/keys.rb
+++ b/activesupport/lib/active_support/core_ext/hash/keys.rb
@@ -1,47 +1,120 @@
 class Hash
-  # Return a new hash with all keys converted to strings.
-  def stringify_keys
-    dup.stringify_keys!
+  # Return a new hash with all keys converted using the block operation.
+  #
+  #  { :name => 'Rob', :years => '28' }.transform_keys{ |key| key.to_s.upcase }
+  #  # => { "NAME" => "Rob", "YEARS" => "28" }
+  def transform_keys
+    result = {}
+    keys.each do |key|
+      result[yield(key)] = self[key]
+    end
+    result
   end
 
-  # Destructively convert all keys to strings.
-  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.
+  #
+  #   { :name => 'Rob', :years => '28' }.stringify_keys
+  #   #=> { "name" => "Rob", "years" => "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" }
   def symbolize_keys
-    dup.symbolize_keys!
+    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+.
+  # to +to_sym+. Same as +symbolize_keys+, but modifies +self+.
   def symbolize_keys!
-    keys.each do |key|
-      self[(key.to_sym rescue key) || key] = delete(key)
-    end
-    self
+    transform_keys!{ |key| key.to_sym rescue key }
   end
-
-  alias_method :to_options,  :symbolize_keys
   alias_method :to_options!, :symbolize_keys!
 
   # Validate all keys in a hash match *valid keys, raising ArgumentError on a mismatch.
   # Note that keys are NOT treated indifferently, meaning if you use strings for keys but assert symbols
   # as keys, this will fail.
   #
-  # ==== Examples
-  #   { :name => "Rob", :years => "28" }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: years"
-  #   { :name => "Rob", :age => "28" }.assert_valid_keys("name", "age") # => raises "ArgumentError: Unknown key: name"
-  #   { :name => "Rob", :age => "28" }.assert_valid_keys(:name, :age) # => passes, raises nothing
+  #   { :name => 'Rob', :years => '28' }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: years"
+  #   { :name => 'Rob', :age => '28' }.assert_valid_keys('name', 'age') # => raises "ArgumentError: Unknown key: name"
+  #   { :name => 'Rob', :age => '28' }.assert_valid_keys(:name, :age) # => passes, raises nothing
   def assert_valid_keys(*valid_keys)
     valid_keys.flatten!
     each_key do |k|
-      raise(ArgumentError, "Unknown key: #{k}") unless valid_keys.include?(k)
+      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.
+  #
+  #  { :person => { :name => 'Rob', :years => '28' } }.deep_transform_keys{ |key| key.to_s.upcase }
+  #  # => { "PERSON" => { "NAME" => "Rob", "YEARS" => "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.
+  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
+
+  # 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
+
+  # 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.
+  def deep_symbolize_keys
+    deep_transform_keys{ |key| key.to_sym rescue key }
+  end
 end