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84 lines
2.7 KiB
Go
84 lines
2.7 KiB
Go
// Copyright (c) 2015, Emir Pasic. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package singlylinkedlist
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import "github.com/emirpasic/gods/v2/containers"
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// Assert Iterator implementation
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var _ containers.IteratorWithIndex[int] = (*Iterator[int])(nil)
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// Iterator holding the iterator's state
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type Iterator[T comparable] struct {
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list *List[T]
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index int
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element *element[T]
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}
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// Iterator returns a stateful iterator whose values can be fetched by an index.
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func (list *List[T]) Iterator() *Iterator[T] {
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return &Iterator[T]{list: list, index: -1, element: nil}
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}
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// Next moves the iterator to the next element and returns true if there was a next element in the container.
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// If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
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// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
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// Modifies the state of the iterator.
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func (iterator *Iterator[T]) Next() bool {
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if iterator.index < iterator.list.size {
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iterator.index++
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}
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if !iterator.list.withinRange(iterator.index) {
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iterator.element = nil
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return false
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}
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if iterator.index == 0 {
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iterator.element = iterator.list.first
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} else {
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iterator.element = iterator.element.next
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}
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return true
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}
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// Value returns the current element's value.
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// Does not modify the state of the iterator.
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func (iterator *Iterator[T]) Value() T {
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return iterator.element.value
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}
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// Index returns the current element's index.
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// Does not modify the state of the iterator.
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func (iterator *Iterator[T]) Index() int {
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return iterator.index
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}
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// Begin resets the iterator to its initial state (one-before-first)
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// Call Next() to fetch the first element if any.
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func (iterator *Iterator[T]) Begin() {
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iterator.index = -1
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iterator.element = nil
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}
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// First moves the iterator to the first element and returns true if there was a first element in the container.
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// If First() returns true, then first element's index and value can be retrieved by Index() and Value().
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// Modifies the state of the iterator.
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func (iterator *Iterator[T]) First() bool {
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iterator.Begin()
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return iterator.Next()
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}
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// NextTo moves the iterator to the next element from current position that satisfies the condition given by the
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// passed function, and returns true if there was a next element in the container.
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// If NextTo() returns true, then next element's index and value can be retrieved by Index() and Value().
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// Modifies the state of the iterator.
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func (iterator *Iterator[T]) NextTo(f func(index int, value T) bool) bool {
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for iterator.Next() {
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index, value := iterator.Index(), iterator.Value()
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if f(index, value) {
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return true
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}
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}
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return false
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}
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