Add Enumerable#zip

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

@@ -615,4 +615,34 @@ module Enumerable
     end
     nil
   end
+
+  ##
+  #  call-seq:
+  #     enum.zip(arg, ...)                  -> an_array_of_array
+  #
+  #  Takes one element from <i>enum</i> and merges corresponding
+  #  elements from each <i>args</i>.  This generates a sequence of
+  #  <em>n</em>-element arrays, where <em>n</em> is one more than the
+  #  count of arguments.  The length of the resulting sequence will be
+  #  <code>enum#size</code>.  If the size of any argument is less than
+  #  <code>enum#size</code>, <code>nil</code> values are supplied.
+  #
+
+  def zip(*arg)
+    ary = []
+    i = 0
+    self.each do |val|
+      a = []
+      a.push(val)
+      idx = 0
+      while idx < arg.size
+        a2 = arg[idx].to_a
+        a.push(a2[i])
+        idx += 1
+      end
+      ary.push(a)
+      i += 1
+    end
+    ary
+  end
 end

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

@@ -135,3 +135,12 @@ assert("Enumerable#find_index") do
   assert_equal 34, (1..100).find_index { |i| i % 5 == 0 and i % 7 == 0 }
   assert_equal 49 ,(1..100).find_index(50)
 end
+
+assert("Enumerable#zip") do
+  a = [ 4, 5, 6 ]
+  b = [ 7, 8, 9 ]
+  assert_equal [[4, 7], [5, 8], [6, 9]], a.zip(b)
+  assert_equal [[1, 4, 7], [2, 5, 8], [3, 6, 9]], [1, 2, 3].zip(a, b)
+  assert_equal [[1, 4, 7], [2, 5, 8]], [1, 2].zip(a, b)
+  assert_equal [[4, 1, 8], [5, 2, nil], [6, nil, nil]], a.zip([1, 2], [8])
+end