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- // Copyright (c) 2015, Emir Pasic. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
-
- package binaryheap
-
- import "github.com/emirpasic/gods/containers"
-
- func assertIteratorImplementation() {
- var _ containers.ReverseIteratorWithIndex = (*Iterator)(nil)
- }
-
- // Iterator returns a stateful iterator whose values can be fetched by an index.
- type Iterator struct {
- heap *Heap
- index int
- }
-
- // Iterator returns a stateful iterator whose values can be fetched by an index.
- func (heap *Heap) Iterator() Iterator {
- return Iterator{heap: heap, index: -1}
- }
-
- // 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() {
- iterator.index++
- }
- return iterator.heap.withinRange(iterator.index)
- }
-
- // 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.
- func (iterator *Iterator) Prev() bool {
- if iterator.index >= 0 {
- iterator.index--
- }
- return iterator.heap.withinRange(iterator.index)
- }
-
- // Value returns the current element's value.
- // Does not modify the state of the iterator.
- func (iterator *Iterator) Value() interface{} {
- value, _ := iterator.heap.list.Get(iterator.index)
- return value
- }
-
- // Index returns the current element's index.
- // Does not modify the state of the iterator.
- func (iterator *Iterator) Index() int {
- return iterator.index
- }
-
- // Begin resets the iterator to its initial state (one-before-first)
- // Call Next() to fetch the first element if any.
- func (iterator *Iterator) Begin() {
- iterator.index = -1
- }
-
- // End moves the iterator past the last element (one-past-the-end).
- // Call Prev() to fetch the last element if any.
- func (iterator *Iterator) End() {
- iterator.index = iterator.heap.Size()
- }
-
- // First moves the iterator to the first element and returns true if there was a first element in the container.
- // If First() returns true, then first element's index and value can be retrieved by Index() and Value().
- // Modifies the state of the iterator.
- func (iterator *Iterator) First() bool {
- iterator.Begin()
- return iterator.Next()
- }
-
- // 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.End()
- return iterator.Prev()
- }
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