indexable.rb in facets-2.1.1

- old
+ new

@@ -26,9 +26,45 @@
   #  a = [1,2]
   #  a.last! 3
   #  p a           #=> [1,2,3]
   #
   alias_method :last!, :pop
+
+  # Iteration object.
+
+  class It
+    attr_reader :index, :value, :prior, :after
+    def initialize(array)
+      @array = array
+      @index = 0
+      @value = array[0]
+      @prior = []
+      @after = array[1..-1]
+    end
+    def first? ; @index == 0 ; end
+    def last?  ; @index == @array.length ; end
+    private
+    def next_iteration
+      @index += 1
+      @prior << @value
+      @value = @after.shift
+    end
+  end
+
+  # Iterate over each element of array using an iteration object.
+
+  def each_iteration
+    if block_given?
+      it = It.new(self)
+      each do |e|
+        yield(it)
+        it.send(:next_iteration)
+      end
+    else
+      return Enumerable::Enumerator.new(self, :each_iteration)
+    end
+  end
+
 end
 
 
 =begin
 class Array