add a Mutable container trait with clear

1 files changed, 6 insertions, 3 deletions

diff --git a/src/libstd/priority_queue.rs b/src/libstd/priority_queue.rs
index b9c040de42a..0ff40b6421a 100644
--- a/src/libstd/priority_queue.rs
+++ b/src/libstd/priority_queue.rs
@@ -10,6 +10,7 @@
 
 //! A priority queue implemented with a binary heap
 
+use core::container::Mutable;
 use core::cmp::Ord;
 use core::prelude::*;
 use core::ptr::addr_of;
@@ -24,6 +25,11 @@ pub struct PriorityQueue <T: Ord>{
     priv data: ~[T],
 }
 
+impl <T: Ord> PriorityQueue<T>: Mutable {
+    /// Drop all items from the queue
+    fn clear(&mut self) { self.data.truncate(0) }
+}
+
 impl <T: Ord> PriorityQueue<T> {
     /// Returns the greatest item in the queue - fails if empty
     pure fn top(&self) -> &self/T { &self.data[0] }
@@ -51,9 +57,6 @@ impl <T: Ord> PriorityQueue<T> {
         vec::reserve_at_least(&mut self.data, n)
     }
 
-    /// Drop all items from the queue
-    fn clear(&mut self) { self.data.truncate(0) }
-
     /// Pop the greatest item from the queue - fails if empty
     fn pop(&mut self) -> T {
         let mut item = self.data.pop();