- iterator last on all structures with reversible iterators

containers/iterator.go

@@ -64,12 +64,20 @@ type IteratorWithKey interface {
 
 // ReverseIteratorWithIndex is stateful iterator for ordered containers whose values can be fetched by an index.
 //
-// Essentially it is the same as IteratorWithIndex, but provides additional Prev() function to enable traversal in reverse.
+// Essentially it is the same as IteratorWithIndex, but provides additional:
+//
+// Prev() function to enable traversal in reverse
+//
+// Last() function to move the iterator to the last element.
 type ReverseIteratorWithIndex interface {
 	// Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
 	// If Prev() returns true, then previous element's index and value can be retrieved by Index() and Value().
 	// Modifies the state of the iterator.
 	Prev() bool
+	// Last moves the iterator to the last element and returns true if there was a last element in the container.
+	// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
+	// Modifies the state of the iterator.
+	Last() bool
 
 	IteratorWithIndex
 	// Next() bool
@@ -79,12 +87,20 @@ type ReverseIteratorWithIndex interface {
 
 // ReverseIteratorWithKey is a stateful iterator for ordered containers whose elements are key value pairs.
 //
-// Essentially it is the same as IteratorWithKey, but provides additional Prev() function to enable traversal in reverse.
+// Essentially it is the same as IteratorWithKey, but provides additional:
+//
+// Prev() function to enable traversal in reverse
+//
+// Last() function to move the iterator to the last element.
 type ReverseIteratorWithKey interface {
 	// Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
 	// If Prev() returns true, then previous element's index and value can be retrieved by Key() and Value().
 	// Modifies the state of the iterator.
 	Prev() bool
+	// Last moves the iterator to the last element and returns true if there was a last element in the container.
+	// If Last() returns true, then last element's index and value can be retrieved by Key() and Value().
+	// Modifies the state of the iterator.
+	Last() bool
 
 	IteratorWithKey
 	// Next() bool

lists/arraylist/arraylist.go

@@ -230,6 +230,14 @@ func (iterator *Iterator) Reset() {
 	iterator.index = -1
 }
 
+// Last moves the iterator to the last element and returns true if there was a last element in the container.
+// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
+// Modifies the state of the iterator.
+func (iterator *Iterator) Last() bool {
+	iterator.index = iterator.list.size
+	return iterator.Prev()
+}
+
 // 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

@@ -370,6 +370,15 @@ func (iterator *Iterator) Reset() {
 	iterator.element = nil
 }
 
+// Last moves the iterator to the last element and returns true if there was a last element in the container.
+// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
+// Modifies the state of the iterator.
+func (iterator *Iterator) Last() bool {
+	iterator.index = iterator.list.size
+	iterator.element = iterator.list.last
+	return iterator.Prev()
+}
+
 // 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

@@ -171,6 +171,13 @@ func (iterator *Iterator) Reset() {
 	iterator.iterator.Reset()
 }
 
+// Last moves the iterator to the last element and returns true if there was a last element in the container.
+// If Last() returns true, then last element's index and value can be retrieved by Key() and Value().
+// Modifies the state of the iterator.
+func (iterator *Iterator) Last() bool {
+	return iterator.iterator.Last()
+}
+
 // 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

@@ -158,6 +158,14 @@ func (iterator *Iterator) Reset() {
 	iterator.iterator.Reset()
 }
 
+// Last moves the iterator to the last element and returns true if there was a last element in the container.
+// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
+// Modifies the state of the iterator.
+func (iterator *Iterator) Last() bool {
+	iterator.index = iterator.tree.Size()
+	return iterator.iterator.Last()
+}
+
 // 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

@@ -149,6 +149,14 @@ func (iterator *Iterator) Reset() {
 	iterator.index = -1
 }
 
+// Last moves the iterator to the last element and returns true if there was a last element in the container.
+// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
+// Modifies the state of the iterator.
+func (iterator *Iterator) Last() bool {
+	iterator.index = iterator.stack.Size()
+	return iterator.Prev()
+}
+
 // String returns a string representation of container
 func (stack *Stack) String() string {
 	str := "ArrayStack\n"

trees/binaryheap/binaryheap.go

@@ -165,6 +165,14 @@ func (iterator *Iterator) Reset() {
 	iterator.index = -1
 }
 
+// Last moves the iterator to the last element and returns true if there was a last element in the container.
+// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
+// Modifies the state of the iterator.
+func (iterator *Iterator) Last() bool {
+	iterator.index = iterator.heap.Size()
+	return iterator.Prev()
+}
+
 // String returns a string representation of container
 func (heap *Heap) String() string {
 	str := "BinaryHeap\n"

trees/redblacktree/redblacktree.go

@@ -363,6 +363,14 @@ func (iterator *Iterator) Reset() {
 	iterator.node = nil
 }
 
+// Last moves the iterator to the last element and returns true if there was a last element in the container.
+// If Last() returns true, then last element's index and value can be retrieved by Key() and Value().
+// Modifies the state of the iterator.
+func (iterator *Iterator) Last() bool {
+	iterator.node = iterator.tree.Right()
+	return iterator.node != nil
+}
+
 // String returns a string representation of container
 func (tree *Tree) String() string {
 	str := "RedBlackTree\n"