added RSpec and RSpec on Rails

vendor/gems/rspec-1.1.2/examples/pure/stack.rb

@@ -0,0 +1,36 @@
+class StackUnderflowError < RuntimeError
+end
+
+class StackOverflowError < RuntimeError
+end
+
+class Stack
+  
+  def initialize
+    @items = []
+  end
+  
+  def push object
+    raise StackOverflowError if @items.length == 10
+    @items.push object
+  end
+  
+  def pop
+    raise StackUnderflowError if @items.empty?
+    @items.delete @items.last
+  end
+  
+  def peek
+    raise StackUnderflowError if @items.empty?
+    @items.last
+  end
+  
+  def empty?
+    @items.empty?
+  end
+
+  def full?
+    @items.length == 10
+  end
+  
+end