Add `Hash#transform_{keys,values}` to `mruby-hash-ext`.

mrbgems/mruby-hash-ext/mrbgem.rake

@@ -2,6 +2,7 @@ MRuby::Gem::Specification.new('mruby-hash-ext') do |spec|
   spec.license = 'MIT'
   spec.author  = 'mruby developers'
   spec.summary = 'Hash class extension'
-  spec.add_dependency 'mruby-enum-ext', :core => 'mruby-enum-ext'
-  spec.add_dependency 'mruby-array-ext', :core => 'mruby-array-ext'
+  spec.add_dependency 'mruby-enum-ext', core: 'mruby-enum-ext'
+  spec.add_dependency 'mruby-array-ext', core: 'mruby-array-ext'
+  spec.add_test_dependency 'mruby-enumerator', core: 'mruby-enumerator'
 end

mrbgems/mruby-hash-ext/mrblib/hash.rb

@@ -382,4 +382,43 @@ class Hash
       n
     end
   end
+
+  ##
+  # call-seq:
+  #    hsh.transform_keys {|key| block } -> new_hash
+  #    hsh.transform_keys                -> an_enumerator
+  #
+  # Returns a new hash, with the keys computed from running the block
+  # once for each key in the hash, and the values unchanged.
+  #
+  # If no block is given, an enumerator is returned instead.
+  #
+  def transform_keys(&b)
+    return to_enum :transform_keys unless block_given?
+    hash = {}
+    self.each_key do |k|
+      new_key = yield(k)
+      hash[new_key] = self[k]
+    end
+    hash
+  end
+  ##
+  # call-seq:
+  #    hsh.transform_values {|value| block } -> new_hash
+  #    hsh.transform_values                  -> an_enumerator
+  #
+  # Returns a new hash with the results of running the block once for
+  # every value.
+  # This method does not change the keys.
+  #
+  # If no block is given, an enumerator is returned instead.
+  #
+  def transform_values(&b)
+    return to_enum :transform_values unless block_given?
+    hash = {}
+    self.each_key do |k|
+      hash[k] = yield(self[k])
+    end
+    hash
+  end
 end

mrbgems/mruby-hash-ext/test/hash.rb

@@ -254,3 +254,29 @@ assert("Hash#dig") do
   assert_equal(1, h.dig(:a, :b, :c))
   assert_nil(h.dig(:d))
 end
+
+assert("Hash#transform_keys") do
+  h = {a:{b:{c:1}}}
+  assert_equal(1, h.dig(:a, :b, :c))
+  assert_nil(h.dig(:d))
+end
+
+assert("Hash#transform_keys") do
+  h = {"1" => 100, "2" => 200}
+  assert_equal(h.transform_keys{|k| k+"!"},
+               {"1!" => 100, "2!" => 200})
+  assert_equal(h.transform_keys{|k|k.to_i},
+               {1 => 100, 2 => 200})
+  assert_equal(h.transform_keys.with_index{|k, i| "#{k}.#{i}"},
+               {"1.0" => 100, "2.1" => 200})
+end
+
+assert("Hash#transform_values") do
+  h = {a: 1, b: 2, c: 3}
+  assert_equal(h.transform_values{|v| v * v + 1},
+               {a: 2, b: 5, c: 10})
+  assert_equal(h.transform_values{|v|v.to_s},
+               {a: "1", b: "2", c: "3"})
+  assert_equal(h.transform_values.with_index{|v, i| "#{v}.#{i}"},
+               {a: "1.0", b: "2.1", c: "3.2"})
+end