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112 lines
4.1 KiB
Go
112 lines
4.1 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 arraystack
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import "github.com/emirpasic/gods/containers"
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// Assert Iterator implementation
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var _ containers.ReverseIteratorWithIndex = (*Iterator)(nil)
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// Iterator returns a stateful iterator whose values can be fetched by an index.
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type Iterator struct {
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stack *Stack
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index int
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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 (stack *Stack) Iterator() Iterator {
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return Iterator{stack: stack, index: -1}
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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) Next() bool {
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if iterator.index < iterator.stack.Size() {
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iterator.index++
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}
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return iterator.stack.withinRange(iterator.index)
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}
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// Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
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// If Prev() returns true, then previous 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) Prev() bool {
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if iterator.index >= 0 {
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iterator.index--
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}
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return iterator.stack.withinRange(iterator.index)
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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) Value() interface{} {
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value, _ := iterator.stack.list.Get(iterator.stack.list.Size() - iterator.index - 1) // in reverse (LIFO)
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return 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) 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) Begin() {
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iterator.index = -1
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}
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// End moves the iterator past the last element (one-past-the-end).
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// Call Prev() to fetch the last element if any.
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func (iterator *Iterator) End() {
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iterator.index = iterator.stack.Size()
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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) First() bool {
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iterator.Begin()
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return iterator.Next()
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}
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// Last moves the iterator to the last element and returns true if there was a last element in the container.
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// If Last() returns true, then last 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) Last() bool {
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iterator.End()
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return iterator.Prev()
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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) NextTo(f func(index int, value interface{}) 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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// PrevTo moves the iterator to the previous 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 PrevTo() 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) PrevTo(f func(index int, value interface{}) bool) bool {
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for iterator.Prev() {
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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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