1 files changed, 164 insertions, 0 deletions
diff --git a/mrbgems/mruby-enum-ext/mrblib/enum.rb b/mrbgems/mruby-enum-ext/mrblib/enum.rb
new file mode 100644
index 000000000..f250d39f1
--- /dev/null
+++ b/mrbgems/mruby-enum-ext/mrblib/enum.rb
@@ -0,0 +1,164 @@
+##
+# Enumerable
+#
+module Enumerable
+  ##
+  # call-seq:
+  #    enum.drop(n)               -> array
+  #
+  # Drops first n elements from <i>enum</i>, and returns rest elements
+  # in an array.
+  #
+  #    a = [1, 2, 3, 4, 5, 0]
+  #    a.drop(3)             #=> [4, 5, 0]
+
+  def drop(n)
+    raise TypeError, "expected Integer for 1st argument" unless n.kind_of? Integer
+    raise ArgumentError, "attempt to drop negative size" if n < 0
+
+    ary = []
+    self.each {|e| n == 0 ? ary << e : n -= 1 }
+    ary
+  end
+
+  ##
+  # call-seq:
+  #    enum.drop_while {|arr| block }   -> array
+  #
+  # Drops elements up to, but not including, the first element for
+  # which the block returns +nil+ or +false+ and returns an array
+  # containing the remaining elements.
+  #
+  #    a = [1, 2, 3, 4, 5, 0]
+  #    a.drop_while {|i| i < 3 }   #=> [3, 4, 5, 0]
+
+  def drop_while(&block)
+    ary, state = [], false
+    self.each do |e|
+      state = true if !state and !block.call(e)
+      ary << e if state
+    end
+    ary
+  end
+
+  ##
+  # call-seq:
+  #    enum.take(n)               -> array
+  #
+  # Returns first n elements from <i>enum</i>.
+  #
+  #    a = [1, 2, 3, 4, 5, 0]
+  #    a.take(3)             #=> [1, 2, 3]
+
+  def take(n)
+    raise TypeError, "expected Integer for 1st argument" unless n.kind_of? Integer
+    raise ArgumentError, "attempt to take negative size" if n < 0
+
+    ary = []
+    self.each do |e|
+      break if ary.size >= n
+      ary << e
+    end
+    ary
+  end
+
+  ##
+  # call-seq:
+  #    enum.take_while {|arr| block }   -> array
+  #
+  # Passes elements to the block until the block returns +nil+ or +false+,
+  # then stops iterating and returns an array of all prior elements.
+  #
+  #
+  #    a = [1, 2, 3, 4, 5, 0]
+  #    a.take_while {|i| i < 3 }   #=> [1, 2]
+
+  def take_while(&block)
+    ary = []
+    self.each do |e|
+      return ary unless block.call(e)
+      ary << e
+    end
+    ary
+  end
+  
+  ##
+  # call-seq:
+  #   enum.each_cons(n) {...}   ->  nil
+  #
+  # Iterates the given block for each array of consecutive <n>
+  # elements.
+  #
+  # e.g.:
+  #     (1..10).each_cons(3) {|a| p a}
+  #     # outputs below
+  #     [1, 2, 3]
+  #     [2, 3, 4]
+  #     [3, 4, 5]
+  #     [4, 5, 6]
+  #     [5, 6, 7]
+  #     [6, 7, 8]
+  #     [7, 8, 9]
+  #     [8, 9, 10]
+
+  def each_cons(n, &block)
+    raise TypeError, "expected Integer for 1st argument" unless n.kind_of? Integer
+    raise ArgumentError, "invalid size" if n <= 0
+
+    ary = []
+    self.each do |e|
+      ary.shift if ary.size == n
+      ary << e
+      block.call(ary.dup) if ary.size == n
+    end
+  end
+
+  ##
+  # call-seq:
+  #   enum.each_slice(n) {...}  ->  nil
+  #
+  # Iterates the given block for each slice of <n> elements.
+  #
+  # e.g.:
+  #     (1..10).each_slice(3) {|a| p a}
+  #     # outputs below
+  #     [1, 2, 3]
+  #     [4, 5, 6]
+  #     [7, 8, 9]
+  #     [10]
+
+  def each_slice(n, &block)
+    raise TypeError, "expected Integer for 1st argument" unless n.kind_of? Integer
+    raise ArgumentError, "invalid slice size" if n <= 0
+
+    ary = []
+    self.each do |e|
+      ary << e
+      if ary.size == n
+        block.call(ary)
+        ary = []
+      end
+    end
+    block.call(ary) unless ary.empty?
+  end
+
+  ##
+  # call-seq:
+  #    enum.group_by {| obj | block }  -> a_hash
+  #
+  # Returns a hash, which keys are evaluated result from the
+  # block, and values are arrays of elements in <i>enum</i>
+  # corresponding to the key.
+  #
+  #    (1..6).group_by {|i| i%3}   #=> {0=>[3, 6], 1=>[1, 4], 2=>[2, 5]}
+
+  def group_by(&block)
+    h = {}
+    self.each do |e|
+      key = block.call(e)
+      h.key?(key) ? (h[key] << e) : (h[key] = [e])
+    end
+    h
+  end
+
+end