From f5eefc6765e683b83e2694f6387f3a54b11a5d24 Mon Sep 17 00:00:00 2001
From: Markus Ewald <cygon@nuclex.org>
Date: Tue, 15 Jul 2008 20:36:16 +0000
Subject: [PATCH] Added Peek() method to the priority queue classes (it's a
 method and not a property because it can potentially fail with an exception
 and a property might lead someone to not think about this possibility)

git-svn-id: file:///srv/devel/repo-conversion/nusu@79 d2e56fa2-650e-0410-a79f-9358c0239efd
---
 Source/Collections/PairPriorityQueue.cs |  6 ++++++
 Source/Collections/PriorityQueue.cs     | 15 +++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Source/Collections/PairPriorityQueue.cs b/Source/Collections/PairPriorityQueue.cs
index c3f316b..1b05ffa 100644
--- a/Source/Collections/PairPriorityQueue.cs
+++ b/Source/Collections/PairPriorityQueue.cs
@@ -73,6 +73,12 @@ namespace Nuclex.Support.Collections {
       );
     }
 
+    /// <summary>Returns the topmost item in the queue without dequeueing it</summary>
+    /// <returns>The topmost item in the queue</returns>
+    public PriorityItemPair<PriorityType, ItemType> Peek() {
+      return this.internalQueue.Peek();
+    }
+
     /// <summary>Takes the item with the highest priority off from the queue</summary>
     /// <returns>The item with the highest priority in the list</returns>
     public PriorityItemPair<PriorityType, ItemType> Dequeue() {
diff --git a/Source/Collections/PriorityQueue.cs b/Source/Collections/PriorityQueue.cs
index 934d12e..ca3706c 100644
--- a/Source/Collections/PriorityQueue.cs
+++ b/Source/Collections/PriorityQueue.cs
@@ -107,12 +107,23 @@ namespace Nuclex.Support.Collections {
       this.heap = new ItemType[this.capacity];
     }
 
+    /// <summary>Returns the topmost item in the queue without dequeueing it</summary>
+    /// <returns>The topmost item in the queue</returns>
+    public ItemType Peek() {
+      if(this.count == 0) {
+        throw new InvalidOperationException("No items queued");
+      }
+
+      return this.heap[0];
+    }
+
     /// <summary>Takes the item with the highest priority off from the queue</summary>
     /// <returns>The item with the highest priority in the list</returns>
     /// <exception cref="InvalidOperationException">When the queue is empty</exception>
     public ItemType Dequeue() {
-      if(count == 0)
+      if(this.count == 0) {
         throw new InvalidOperationException("No items available to dequeue");
+      }
 
       ItemType result = this.heap[0];
       --this.count;
@@ -150,7 +161,7 @@ namespace Nuclex.Support.Collections {
     /// <param name="array">Array to copy the priority queue into</param>
     /// <param name="index">Starting index for the destination array</param>
     public void CopyTo(Array array, int index) {
-      Array.Copy(heap, 0, array, index, this.count);
+      Array.Copy(this.heap, 0, array, index, this.count);
     }
 
     /// <summary>