github.com/mymmsc/gox@v1.3.33/util/linkedliststack/linkedliststack.go (about)

     1  // Copyright (c) 2015, Emir Pasic. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package linkedliststack implements a stack backed by a singly-linked list.
     6  //
     7  // Structure is not thread safe.
     8  //
     9  // Reference:https://en.wikipedia.org/wiki/Stack_%28abstract_data_type%29#Linked_list
    10  package linkedliststack
    11  
    12  import (
    13  	"fmt"
    14  	"github.com/mymmsc/gox/util"
    15  	"github.com/mymmsc/gox/util/singlylinkedlist"
    16  	"strings"
    17  )
    18  
    19  func assertStackImplementation() {
    20  	var _ util.Stack = (*Stack)(nil)
    21  }
    22  
    23  // Stack holds elements in a singly-linked-list
    24  type Stack struct {
    25  	list *singlylinkedlist.List
    26  }
    27  
    28  // New nnstantiates a new empty stack
    29  func New() *Stack {
    30  	return &Stack{list: &singlylinkedlist.List{}}
    31  }
    32  
    33  // Push adds a value onto the top of the stack
    34  func (stack *Stack) Push(value interface{}) {
    35  	stack.list.Prepend(value)
    36  }
    37  
    38  // Pop removes top element on stack and returns it, or nil if stack is empty.
    39  // Second return parameter is true, unless the stack was empty and there was nothing to pop.
    40  func (stack *Stack) Pop() (value interface{}, ok bool) {
    41  	value, ok = stack.list.Get(0)
    42  	stack.list.Remove(0)
    43  	return
    44  }
    45  
    46  // Peek returns top element on the stack without removing it, or nil if stack is empty.
    47  // Second return parameter is true, unless the stack was empty and there was nothing to peek.
    48  func (stack *Stack) Peek() (value interface{}, ok bool) {
    49  	return stack.list.Get(0)
    50  }
    51  
    52  // Empty returns true if stack does not contain any elements.
    53  func (stack *Stack) Empty() bool {
    54  	return stack.list.Empty()
    55  }
    56  
    57  // Size returns number of elements within the stack.
    58  func (stack *Stack) Size() int {
    59  	return stack.list.Size()
    60  }
    61  
    62  // Clear removes all elements from the stack.
    63  func (stack *Stack) Clear() {
    64  	stack.list.Clear()
    65  }
    66  
    67  // Values returns all elements in the stack (LIFO order).
    68  func (stack *Stack) Values() []interface{} {
    69  	return stack.list.Values()
    70  }
    71  
    72  // String returns a string representation of container
    73  func (stack *Stack) String() string {
    74  	str := "LinkedListStack\n"
    75  	values := []string{}
    76  	for _, value := range stack.list.Values() {
    77  		values = append(values, fmt.Sprintf("%v", value))
    78  	}
    79  	str += strings.Join(values, ", ")
    80  	return str
    81  }
    82  
    83  // Check that the index is within bounds of the list
    84  func (stack *Stack) withinRange(index int) bool {
    85  	return index >= 0 && index < stack.list.Size()
    86  }