Merge pull request kanwei#10 from loganb/master

Fix 1.9 compile error and add Heap#next_key method

Author: kanwei

ext/algorithms/string/string.c

@@ -11,10 +11,10 @@ int min(int a, int b, int c) {
 
 int levenshtein_distance(VALUE str1, VALUE str2) {
 	int i, j, s1_len, s2_len, *d;
-	char * s = RSTRING(str1)->ptr;
-	char * t = RSTRING(str2)->ptr;
-	s1_len = RSTRING(str1)->len; 
-	s2_len = RSTRING(str2)->len;
+	char * s = RSTRING_PTR(str1);
+	char * t = RSTRING_PTR(str2);
+	s1_len = RSTRING_LEN(str1); 
+	s2_len = RSTRING_LEN(str2);
 
 	if (s1_len == 0) {
 		return s2_len;

lib/containers/heap.rb

@@ -117,6 +117,22 @@ def next
     @next && @next.value
   end
 
+  # call-seq:
+  #     next_key -> key
+  #     next_key -> nil
+  #
+  # Returns the key associated with the next item in heap order, but does not remove the value.
+  #
+  # Complexity: O(1)
+  #
+  #     minheap = MinHeap.new
+  #     minheap.push(1, :a)
+  #     minheap.next_key #=> 1
+  #
+  def next_key
+    @next && @next.key
+  end
+  
   # call-seq:
   #     clear -> nil
   #

spec/heap_spec.rb

@@ -46,6 +46,11 @@
       @heap.size.should eql(@num_items)
     end
 
+    it "should have a next value" do
+      @heap.next.should be_true
+      @heap.next_key.should be_true
+    end
+    
     it "should delete random keys" do
       @heap.delete(@random_array[0]).should eql(@random_array[0])
       @heap.delete(@random_array[1]).should eql(@random_array[1])