Refactored and renamed functions to avoid failure

diff --git a/src/libcollections/priority_queue.rs b/src/libcollections/priority_queue.rs
index 56878ebd6edaba50028d2de1acc1551dc7fb9112..898b011b23e605effdd5ff8f90ca3203d49d529e 100644 (file)
--- a/src/libcollections/priority_queue.rs
+++ b/src/libcollections/priority_queue.rs
@@ -39,14 +39,14 @@ pub fn iter<'a>(&'a self) -> Items<'a, T> {
         Items { iter: self.data.iter() }
     }
 
-    /// Returns the greatest item in the queue - fails if empty
-    pub fn top<'a>(&'a self) -> &'a T { self.data.get(0) }
-
-    /// Returns the greatest item in the queue - None if empty
-    pub fn maybe_top<'a>(&'a self) -> Option<&'a T> {
-        if self.is_empty() { None } else { Some(self.top()) }
+    /// Returns the greatest item in a queue or None if it is empty
+    pub fn top<'a>(&'a self) -> Option<&'a T> {
+        if self.is_empty() { None } else { Some(self.data.get(0)) }
     }
 
+    #[deprecated="renamed to `top`"]
+    pub fn maybe_top<'a>(&'a self) -> Option<&'a T> { self.top() }
+
     /// Returns the number of elements the queue can hold without reallocating
     pub fn capacity(&self) -> uint { self.data.capacity() }
 
@@ -60,20 +60,23 @@ pub fn reserve(&mut self, n: uint) {
         self.data.reserve(n)
     }
 
-    /// Pop the greatest item from the queue - fails if empty
-    pub fn pop(&mut self) -> T {
-        let mut item = self.data.pop().unwrap();
-        if !self.is_empty() {
-            swap(&mut item, self.data.get_mut(0));
-            self.siftdown(0);
+    /// Remove the greatest item from a queue and return it, or `None` if it is
+    /// empty.
+    pub fn pop(&mut self) -> Option<T> {
+        match self.data.pop() {
+            None           => { None }
+            Some(mut item) => {
+                if !self.is_empty() {
+                    swap(&mut item, self.data.get_mut(0));
+                    self.siftdown(0);
+                }
+                Some(item)
+            }
         }
-        item
     }
 
-    /// Pop the greatest item from the queue - None if empty
-    pub fn maybe_pop(&mut self) -> Option<T> {
-        if self.is_empty() { None } else { Some(self.pop()) }
-    }
+    #[deprecated="renamed to `pop`"]
+    pub fn maybe_pop(&mut self) -> Option<T> { self.pop() }
 
     /// Push an item onto the queue
     pub fn push(&mut self, item: T) {
@@ -84,18 +87,24 @@ pub fn push(&mut self, item: T) {
 
     /// Optimized version of a push followed by a pop
     pub fn push_pop(&mut self, mut item: T) -> T {
-        if !self.is_empty() && *self.top() > item {
+        if !self.is_empty() && *self.top().unwrap() > item {
             swap(&mut item, self.data.get_mut(0));
             self.siftdown(0);
         }
         item
     }
 
-    /// Optimized version of a pop followed by a push - fails if empty
-    pub fn replace(&mut self, mut item: T) -> T {
-        swap(&mut item, self.data.get_mut(0));
-        self.siftdown(0);
-        item
+    /// Optimized version of a pop followed by a push. The push is done
+    /// regardless of whether the queue is empty.
+    pub fn replace(&mut self, mut item: T) -> Option<T> {
+        if !self.is_empty() {
+            swap(&mut item, self.data.get_mut(0));
+            self.siftdown(0);
+            Some(item)
+        } else {
+            self.push(item);
+            None
+        }
     }
 
     #[deprecated="renamed to `into_vec`"]
@@ -117,7 +126,7 @@ pub fn into_sorted_vec(self) -> Vec<T> {
             q.data.as_mut_slice().swap(0, end);
             q.siftdown_range(0, end)
         }
-        q.to_vec()
+        q.into_vec()
     }
 
     /// Create an empty PriorityQueue
@@ -247,8 +256,8 @@ fn test_top_and_pop() {
         sorted.sort();
         let mut heap = PriorityQueue::from_vec(data);
         while !heap.is_empty() {
-            assert_eq!(heap.top(), sorted.last().unwrap());
-            assert_eq!(heap.pop(), sorted.pop().unwrap());
+            assert_eq!(heap.top().unwrap(), sorted.last().unwrap());
+            assert_eq!(heap.pop().unwrap(), sorted.pop().unwrap());
         }
     }
 
@@ -256,44 +265,44 @@ fn test_top_and_pop() {
     fn test_push() {
         let mut heap = PriorityQueue::from_vec(vec!(2, 4, 9));
         assert_eq!(heap.len(), 3);
-        assert!(*heap.top() == 9);
+        assert!(*heap.top().unwrap() == 9);
         heap.push(11);
         assert_eq!(heap.len(), 4);
-        assert!(*heap.top() == 11);
+        assert!(*heap.top().unwrap() == 11);
         heap.push(5);
         assert_eq!(heap.len(), 5);
-        assert!(*heap.top() == 11);
+        assert!(*heap.top().unwrap() == 11);
         heap.push(27);
         assert_eq!(heap.len(), 6);
-        assert!(*heap.top() == 27);
+        assert!(*heap.top().unwrap() == 27);
         heap.push(3);
         assert_eq!(heap.len(), 7);
-        assert!(*heap.top() == 27);
+        assert!(*heap.top().unwrap() == 27);
         heap.push(103);
         assert_eq!(heap.len(), 8);
-        assert!(*heap.top() == 103);
+        assert!(*heap.top().unwrap() == 103);
     }
 
     #[test]
     fn test_push_unique() {
         let mut heap = PriorityQueue::from_vec(vec!(box 2, box 4, box 9));
         assert_eq!(heap.len(), 3);
-        assert!(*heap.top() == box 9);
+        assert!(*heap.top().unwrap() == box 9);
         heap.push(box 11);
         assert_eq!(heap.len(), 4);
-        assert!(*heap.top() == box 11);
+        assert!(*heap.top().unwrap() == box 11);
         heap.push(box 5);
         assert_eq!(heap.len(), 5);
-        assert!(*heap.top() == box 11);
+        assert!(*heap.top().unwrap() == box 11);
         heap.push(box 27);
         assert_eq!(heap.len(), 6);
-        assert!(*heap.top() == box 27);
+        assert!(*heap.top().unwrap() == box 27);
         heap.push(box 3);
         assert_eq!(heap.len(), 7);
-        assert!(*heap.top() == box 27);
+        assert!(*heap.top().unwrap() == box 27);
         heap.push(box 103);
         assert_eq!(heap.len(), 8);
-        assert!(*heap.top() == box 103);
+        assert!(*heap.top().unwrap() == box 103);
     }
 
     #[test]
@@ -314,24 +323,24 @@ fn test_push_pop() {
     fn test_replace() {
         let mut heap = PriorityQueue::from_vec(vec!(5, 5, 2, 1, 3));
         assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(6), 5);
+        assert_eq!(heap.replace(6).unwrap(), 5);
         assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(0), 6);
+        assert_eq!(heap.replace(0).unwrap(), 6);
         assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(4), 5);
+        assert_eq!(heap.replace(4).unwrap(), 5);
         assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(1), 4);
+        assert_eq!(heap.replace(1).unwrap(), 4);
         assert_eq!(heap.len(), 5);
     }
 
     fn check_to_vec(mut data: Vec<int>) {
         let heap = PriorityQueue::from_vec(data.clone());
-        let mut v = heap.clone().to_vec();
+        let mut v = heap.clone().into_vec();
         v.sort();
         data.sort();
 
         assert_eq!(v, data);
-        assert_eq!(heap.to_sorted_vec(), data);
+        assert_eq!(heap.into_sorted_vec(), data);
     }
 
     #[test]
@@ -352,36 +361,21 @@ fn test_to_vec() {
     }
 
     #[test]
-    #[should_fail]
     fn test_empty_pop() {
         let mut heap: PriorityQueue<int> = PriorityQueue::new();
-        heap.pop();
+        assert!(heap.pop().is_none());
     }
 
     #[test]
-    fn test_empty_maybe_pop() {
-        let mut heap: PriorityQueue<int> = PriorityQueue::new();
-        assert!(heap.maybe_pop().is_none());
-    }
-
-    #[test]
-    #[should_fail]
     fn test_empty_top() {
         let empty: PriorityQueue<int> = PriorityQueue::new();
-        empty.top();
-    }
-
-    #[test]
-    fn test_empty_maybe_top() {
-        let empty: PriorityQueue<int> = PriorityQueue::new();
-        assert!(empty.maybe_top().is_none());
+        assert!(empty.top().is_none());
     }
 
     #[test]
-    #[should_fail]
     fn test_empty_replace() {
         let mut heap: PriorityQueue<int> = PriorityQueue::new();
-        heap.replace(5);
+        heap.replace(5).is_none();
     }
 
     #[test]
@@ -391,7 +385,7 @@ fn test_from_iter() {
         let mut q: PriorityQueue<uint> = xs.as_slice().iter().rev().map(|&x| x).collect();
 
         for &x in xs.iter() {
-            assert_eq!(q.pop(), x);
+            assert_eq!(q.pop().unwrap(), x);
         }
     }
 }