make heap api more robust

diff --git a/src/index_heap.rs b/src/index_heap.rs
index 477dc879cf610d95dd8c2658bde1a3227a257cf1..5850ae802a3005775e593a86e1d6091931421d18 100644 (file)
--- a/src/index_heap.rs
+++ b/src/index_heap.rs
@@ -123,19 +123,19 @@ impl<T: Ord + Indexing> IndexdMinHeap<T> {
     }
 
     /// Updates the key of an element if the new key is smaller than the old key.
     }
 
     /// Updates the key of an element if the new key is smaller than the old key.

-    /// Does nothing if the new key is larger.
-    /// Panics if the element is not part of the queue.
+    /// Panics if the element is not part of the queue or if the new key is larger.

     pub fn decrease_key(&mut self, element: T) {
         let position = self.positions[element.as_index()];
     pub fn decrease_key(&mut self, element: T) {
         let position = self.positions[element.as_index()];

+        assert!(element <= self.data[position]);

         self.data[position] = element;
         self.move_up_in_tree(position);
     }
 
     /// Updates the key of an element if the new key is larger than the old key.
         self.data[position] = element;
         self.move_up_in_tree(position);
     }
 
     /// Updates the key of an element if the new key is larger than the old key.

-    /// Does nothing if the new key is smaller.
-    /// Panics if the element is not part of the queue.
+    /// Panics if the element is not part of the queue or if the new key is smaller.

     pub fn increase_key(&mut self, element: T) {
         let position = self.positions[element.as_index()];
     pub fn increase_key(&mut self, element: T) {
         let position = self.positions[element.as_index()];

+        assert!(element >= self.data[position]);

         self.data[position] = element;
         self.move_down_in_tree(position);
     }
         self.data[position] = element;
         self.move_down_in_tree(position);
     }