🐛 Fix issue #2.

Author: trans

History.md

@@ -1,5 +1,22 @@
 # CHANGE HISTORY
 
+## 2.1.0 / 2014-03-03
+
+Ostatnicky has found a bug! As it turns out both #deq and #shift were 
+aliased incorrectly to `push`, when they should have been to `pop`. 
+With this release that has been fixes, but we have modified `shift`
+to instead return the lowest priority item, which is a more polymorphic
+definition with its use in Array. In addition we have added `peek` as
+an alias for `top`, and added `bottom`, which it the opposite of `top`.
+
+Changes:
+
+* Fix `deq` as alias of `pop`, not `push`.
+* Fix `shift` to be like `pop` but opposite priority.
+* Add `peek` as alias of `top`.
+* Add `bottom` method as opposite of `top`.
+
+
 ## 2.0.2 / 2011-10-29
 
 It's been one of those days. I went to to get a wash cloth for the shower,

lib/pqueue.rb

@@ -18,7 +18,7 @@
 class PQueue
 
   #
-  VERSION = "2.0.0"  #:erb: VERSION = "<%= version %>"
+  VERSION = "2.1.0"  #:erb: VERSION = "<%= version %>"
 
   #
   # Returns a new priority queue.
@@ -78,17 +78,17 @@ def push(v)
   end
 
   #
-  # Alias of #push.
+  # Traditional alias for #push.
   #
-  alias :<< :push
+  alias enq push
 
   #
   # Alias of #push.
   #
-  alias enq push
+  alias :<< :push
 
   #
-  # Return the element with the highest priority and remove it from
+  # Get the element with the highest priority and remove it from
   # the queue.
   #
   # The highest priority is determined by the block given at instantiation
@@ -104,14 +104,24 @@ def pop
   end
 
   #
-  # Alias of #push.
+  # Traditional alias for #pop.
   #
-  alias shift push
+  alias deq pop
 
+  # Get the element with the lowest priority and remove it from
+  # the queue.
+  #
+  # The lowest priority is determined by the block given at instantiation
+  # time.
   #
-  # Alias of #pop.
+  # The deletion time is O(log n), with n is the size of the queue.
+  #
+  # Return nil if the queue is empty.
   #
-  alias deq push
+  def shift
+    return nil if empty?
+    @que.shift
+  end
 
   #
   # Returns the element with the highest priority, but
@@ -122,6 +132,20 @@ def top
     return @que.last
   end
 
+  #
+  # Traditional alias for #top.
+  #
+  alias peek top
+
+  #
+  # Returns the element with the lowest priority, but
+  # does not remove it from the queue.
+  #
+  def bottom
+    return nil if empty?
+    return @que.first
+  end
+
   #
   # Add more than one element at the same time. See #push.
   #