feat: Add PopFunc to priorityqueue (#10)

priorityqueue/priorityqueue.go

@@ -68,16 +68,22 @@ func (pq *PriorityQueue[T]) Push(item T) {
 
 // Pop removes and returns the highest priority item from the queue.
 func (pq *PriorityQueue[T]) Pop() (T, bool) {
-	if len(pq.items) == 0 {
-		var zero T
-		return zero, false
+	return pq.PopFunc(func(T) bool { return true })
+}
+
+// PopFunc removes and returns the first item that satisfies the given function.
+func (pq *PriorityQueue[T]) PopFunc(fn func(T) bool) (T, bool) {
+	for i, v := range pq.items {
+		if fn(v) {
+			last := len(pq.items) - 1
+			pq.items[i] = pq.items[last]
+			pq.items = pq.items[:last]
+			pq.down(i)
+			return v, true
+		}
 	}
-	top := pq.items[0]
-	last := len(pq.items) - 1
-	pq.items[0] = pq.items[last]
-	pq.items = pq.items[:last]
-	pq.down(0)
-	return top, true
+	var zero T
+	return zero, false
 }
 
 // Peek returns the highest priority item without removing it.

priorityqueue/priorityqueue_test.go

@@ -260,7 +260,7 @@ type Task struct {
 	priority int
 }
 
-func TestCustomStruct(t *testing.T) {
+func TestPopCustomStruct(t *testing.T) {
 	less := func(a, b Task) bool {
 		return a.priority < b.priority
 	}
@@ -295,6 +295,36 @@ func TestPopEmpty(t *testing.T) {
 	}
 }
 
+func TestPopFunc(t *testing.T) {
+	pq := NewOrdered[int]()
+
+	pq.Push(1)
+	pq.Push(2)
+	pq.Push(3)
+
+	item, ok := pq.PopFunc(
+		func(v int) bool {
+			return v == 2
+		},
+	)
+
+	if !ok {
+		t.Error("Expected to find and remove 2")
+	}
+	if item != 2 {
+		t.Errorf("Expected 2, got %d", item)
+	}
+
+	item, ok = pq.PopFunc(
+		func(v int) bool {
+			return v == 4
+		},
+	)
+	if ok {
+		t.Error("Did not expect to find 4")
+	}
+}
+
 func TestPeekEmpty(t *testing.T) {
 	less := func(a, b int) bool {
 		return a < b