- iterator reset on all structures

containers/iterator.go

@@ -30,6 +30,7 @@ package containers
 type IteratorWithIndex interface {
 	// Next moves the iterator to the next element and returns true if there was a next element in the container.
 	// If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+	// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 	// Modifies the state of the iterator.
 	Next() bool
 	// Value returns the current element's value.
@@ -38,12 +39,16 @@ type IteratorWithIndex interface {
 	// Index returns the current element's index.
 	// Does not modify the state of the iterator.
 	Index() int
+	// Reset sets the iterator to the initial state.
+	// Call Next() to fetch the first element if any.
+	Reset()
 }
 
 // IteratorWithKey is a stateful iterator for ordered containers whose elements are key value pairs.
 type IteratorWithKey interface {
 	// Next moves the iterator to the next element and returns true if there was a next element in the container.
 	// If Next() returns true, then next element's key and value can be retrieved by Key() and Value().
+	// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 	// Modifies the state of the iterator.
 	Next() bool
 	// Value returns the current element's value.
@@ -52,6 +57,9 @@ type IteratorWithKey interface {
 	// Key returns the current element's key.
 	// Does not modify the state of the iterator.
 	Key() interface{}
+	// Reset sets the iterator to the initial state.
+	// Call Next() to fetch the first element if any.
+	Reset()
 }
 
 // ReverseIteratorWithIndex is stateful iterator for ordered containers whose values can be fetched by an index.

lists/arraylist/arraylist.go

@@ -193,6 +193,7 @@ func (list *List) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.index < iterator.list.size {
@@ -223,6 +224,12 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.index = -1
+}
+
 // Each calls the given function once for each element, passing that element's index and value.
 func (list *List) Each(f func(index int, value interface{})) {
 	iterator := list.Iterator()

lists/doublylinkedlist/doublylinkedlist.go

@@ -314,6 +314,7 @@ func (list *List) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.index < iterator.list.size {
@@ -362,6 +363,13 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.index = -1
+	iterator.element = nil
+}
+
 // Each calls the given function once for each element, passing that element's index and value.
 func (list *List) Each(f func(index int, value interface{})) {
 	iterator := list.Iterator()

lists/singlylinkedlist/singlylinkedlist.go

@@ -286,6 +286,7 @@ func (list *List) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.index < iterator.list.size {
@@ -315,6 +316,13 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.index = -1
+	iterator.element = nil
+}
+
 // Each calls the given function once for each element, passing that element's index and value.
 func (list *List) Each(f func(index int, value interface{})) {
 	iterator := list.Iterator()

maps/treemap/treemap.go

@@ -140,6 +140,7 @@ func (m *Map) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's key and value can be retrieved by Key() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	return iterator.iterator.Next()
@@ -164,6 +165,12 @@ func (iterator *Iterator) Key() interface{} {
 	return iterator.iterator.Key()
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.iterator.Reset()
+}
+
 // Each calls the given function once for each element, passing that element's key and value.
 func (m *Map) Each(f func(key interface{}, value interface{})) {
 	iterator := m.Iterator()

sets/treeset/treeset.go

@@ -120,6 +120,7 @@ func (set *Set) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.index < iterator.tree.Size() {
@@ -150,6 +151,12 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.iterator.Reset()
+}
+
 // Each calls the given function once for each element, passing that element's index and value.
 func (set *Set) Each(f func(index int, value interface{})) {
 	iterator := set.Iterator()

stacks/arraystack/arraystack.go

@@ -111,6 +111,7 @@ func (stack *Stack) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.index < iterator.stack.Size() {
@@ -142,6 +143,12 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.index = -1
+}
+
 // String returns a string representation of container
 func (stack *Stack) String() string {
 	str := "ArrayStack\n"

stacks/linkedliststack/linkedliststack.go

@@ -106,6 +106,7 @@ func (stack *Stack) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.index < iterator.stack.Size() {
@@ -127,6 +128,12 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.index = -1
+}
+
 // String returns a string representation of container
 func (stack *Stack) String() string {
 	str := "LinkedListStack\n"

trees/binaryheap/binaryheap.go

@@ -127,6 +127,7 @@ func (heap *Heap) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.index < iterator.heap.Size() {
@@ -158,6 +159,12 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.index = -1
+}
+
 // String returns a string representation of container
 func (heap *Heap) String() string {
 	str := "BinaryHeap\n"

trees/redblacktree/redblacktree.go

@@ -291,6 +291,7 @@ func (tree *Tree) Iterator() Iterator {
 
 // Next moves the iterator to the next element and returns true if there was a next element in the container.
 // If Next() returns true, then next element's key and value can be retrieved by Key() and Value().
+// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
 // Modifies the state of the iterator.
 func (iterator *Iterator) Next() bool {
 	if iterator.node == nil {
@@ -356,6 +357,12 @@ func (iterator *Iterator) Key() interface{} {
 	return iterator.node.Key
 }
 
+// Reset sets the iterator to the initial state.
+// Call Next() to fetch the first element if any.
+func (iterator *Iterator) Reset() {
+	iterator.node = nil
+}
+
 // String returns a string representation of container
 func (tree *Tree) String() string {
 	str := "RedBlackTree\n"