- add iterator to binary heap

trees/binaryheap/binaryheap.go

@@ -33,6 +33,7 @@ package binaryheap
 
 import (
 	"fmt"
+	"github.com/emirpasic/gods/containers"
 	"github.com/emirpasic/gods/lists/arraylist"
 	"github.com/emirpasic/gods/trees"
 	"github.com/emirpasic/gods/utils"
@@ -41,6 +42,7 @@ import (
 
 func assertInterfaceImplementation() {
 	var _ trees.Tree = (*Heap)(nil)
+	var _ containers.Iterator = (*Iterator)(nil)
 }
 
 type Heap struct {
@@ -109,6 +111,29 @@ func (heap *Heap) Values() []interface{} {
 	return heap.list.Values()
 }
 
+type Iterator struct {
+	heap  *Heap
+	index int
+}
+
+func (heap *Heap) Iterator() Iterator {
+	return Iterator{heap: heap, index: -1}
+}
+
+func (iterator *Iterator) Next() bool {
+	iterator.index += 1
+	return iterator.heap.withinRange(iterator.index)
+}
+
+func (iterator *Iterator) Value() interface{} {
+	value, _ := iterator.heap.list.Get(iterator.index)
+	return value
+}
+
+func (iterator *Iterator) Index() interface{} {
+	return iterator.index
+}
+
 func (heap *Heap) String() string {
 	str := "BinaryHeap\n"
 	values := []string{}
@@ -158,3 +183,8 @@ func (heap *Heap) bubbleUp() {
 		index = parentIndex
 	}
 }
+
+// Check that the index is withing bounds of the list
+func (heap *Heap) withinRange(index int) bool {
+	return index >= 0 && index < heap.list.Size()
+}

trees/binaryheap/binaryheap_test.go

@@ -103,7 +103,50 @@ func TestBinaryHeap(t *testing.T) {
 		}
 		prev = curr
 	}
+}
+
+func TestBinaryHeapIterator(t *testing.T) {
+	heap := NewWithIntComparator()
+
+	if actualValue := heap.Empty(); actualValue != true {
+		t.Errorf("Got %v expected %v", actualValue, true)
+	}
+
+	// insertions
+	heap.Push(3)
+	// [3]
+	heap.Push(2)
+	// [2,3]
+	heap.Push(1)
+	// [1,3,2](2 swapped with 1, hence last)
 
+	// Iterator
+	it := heap.Iterator()
+	for it.Next() {
+		index := it.Index()
+		value := it.Value()
+		switch index {
+		case 0:
+			if actualValue, expectedValue := value, 1; actualValue != expectedValue {
+				t.Errorf("Got %v expected %v", actualValue, expectedValue)
+			}
+		case 1:
+			if actualValue, expectedValue := value, 3; actualValue != expectedValue {
+				t.Errorf("Got %v expected %v", actualValue, expectedValue)
+			}
+		case 2:
+			if actualValue, expectedValue := value, 2; actualValue != expectedValue {
+				t.Errorf("Got %v expected %v", actualValue, expectedValue)
+			}
+		default:
+			t.Errorf("Too many")
+		}
+	}
+	heap.Clear()
+	it = heap.Iterator()
+	for it.Next() {
+		t.Errorf("Shouldn't iterate on empty stack")
+	}
 }
 
 func BenchmarkBinaryHeap(b *testing.B) {