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92 lines
2.5 KiB
Go
92 lines
2.5 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 implements a stack backed by array list.
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//
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// Structure is not thread safe.
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//
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// Reference: https://en.wikipedia.org/wiki/Stack_%28abstract_data_type%29#Array
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package arraystack
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import (
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"fmt"
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"github.com/emirpasic/gods/lists/arraylist"
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"github.com/emirpasic/gods/stacks"
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"strings"
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)
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func assertStackImplementation() {
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var _ stacks.Stack = (*Stack)(nil)
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}
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// Stack holds elements in an array-list
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type Stack struct {
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list *arraylist.List
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}
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// New instantiates a new empty stack
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func New() *Stack {
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return &Stack{list: arraylist.New()}
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}
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// Push adds a value onto the top of the stack
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func (stack *Stack) Push(value interface{}) {
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stack.list.Add(value)
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}
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// Pop removes top element on stack and returns it, or nil if stack is empty.
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// Second return parameter is true, unless the stack was empty and there was nothing to pop.
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func (stack *Stack) Pop() (value interface{}, ok bool) {
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value, ok = stack.list.Get(stack.list.Size() - 1)
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stack.list.Remove(stack.list.Size() - 1)
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return
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}
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// Peek returns top element on the stack without removing it, or nil if stack is empty.
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// Second return parameter is true, unless the stack was empty and there was nothing to peek.
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func (stack *Stack) Peek() (value interface{}, ok bool) {
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return stack.list.Get(stack.list.Size() - 1)
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}
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// Empty returns true if stack does not contain any elements.
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func (stack *Stack) Empty() bool {
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return stack.list.Empty()
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}
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// Size returns number of elements within the stack.
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func (stack *Stack) Size() int {
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return stack.list.Size()
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}
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// Clear removes all elements from the stack.
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func (stack *Stack) Clear() {
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stack.list.Clear()
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}
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// Values returns all elements in the stack (LIFO order).
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func (stack *Stack) Values() []interface{} {
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size := stack.list.Size()
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elements := make([]interface{}, size, size)
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for i := 1; i <= size; i++ {
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elements[size-i], _ = stack.list.Get(i - 1) // in reverse (LIFO)
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}
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return elements
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}
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// String returns a string representation of container
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func (stack *Stack) String() string {
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str := "ArrayStack\n"
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values := []string{}
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for _, value := range stack.list.Values() {
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values = append(values, fmt.Sprintf("%v", value))
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}
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str += strings.Join(values, ", ")
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return str
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}
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// Check that the index is within bounds of the list
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func (stack *Stack) withinRange(index int) bool {
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return index >= 0 && index < stack.list.Size()
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}
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