mruby-array-ext: add a new method Array#fetch_values

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

@@ -874,6 +874,27 @@ class Array
   alias prepend unshift
   alias filter! select!
 
+  ##
+  # call-seq:
+  #   ary.fetch_values(idx, ...)                 -> array
+  #   ary.fetch_values(idx, ...) { |i| block } -> array
+  #
+  # Returns an array containing the values associated with the given indexes.
+  # but also raises <code>IndexError</code> when one of indexes can't be found.
+  # Also see <code>Array#values_at</code> and <code>Array#fetch</code>.
+  #
+  #   a = ["cat", "dog", "cow"]
+  #
+  #   a.fetch_values(2, 0)                #=> ["cow", "cat"]
+  #   a.fetch_values(2, 5)                # raises KeyError
+  #   a.fetch_values(2, 5) {|i| "BIRD" }  #=> ["cow", "BIRD"]
+  #
+  def fetch_values(*idx, &block)
+    idx.map do |i|
+      self.fetch(i, &block)
+    end
+  end
+
   ##
   # call-seq:
   #   ary.product(*arys)                  ->   array

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

@@ -174,6 +174,13 @@ assert("Array#fetch") do
   assert_raise(IndexError) { a.fetch(100) }
 end
 
+assert("Array#fetch_values") do
+  a = [ 11, 22, 33, 44 ]
+  assert_equal([33, 11], a.fetch_values(2, 0))
+  assert_raise(IndexError) { a.fetch_values(2, 5) }
+  assert_equal([33, 55], a.fetch_values(2, 5) { |i| i*11 })
+end
+
 assert("Array#fill") do
   a = [ "a", "b", "c", "d" ]
   assert_equal ["x", "x", "x", "x"], a.fill("x")