mirror of https://github.com/emirpasic/gods
array stack (with tests and benchmarks - kinda slow in comparison to the linked list stack)
parent
0f320a5e72
commit
74d7895cfb
@ -0,0 +1,90 @@
|
||||
/*
|
||||
Copyright (c) Emir Pasic, All rights reserved.
|
||||
|
||||
This library is free software; you can redistribute it and/or
|
||||
modify it under the terms of the GNU Lesser General Public
|
||||
License as published by the Free Software Foundation; either
|
||||
version 3.0 of the License, or (at your option) any later version.
|
||||
|
||||
This library is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
Lesser General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU Lesser General Public
|
||||
License along with this library. See the file LICENSE included
|
||||
with this distribution for more information.
|
||||
*/
|
||||
|
||||
// Implementation of stack using a slice.
|
||||
// Use LinkedListStack rather than this Arraystack, because LinkedListStack is a lot faster more memory efficient.
|
||||
// Structure is not thread safe.
|
||||
// References: http://en.wikipedia.org/wiki/Stack_%28abstract_data_type%29
|
||||
|
||||
package arraystack
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"github.com/emirpasic/gods/stacks"
|
||||
"strings"
|
||||
)
|
||||
|
||||
func assertInterfaceImplementation() {
|
||||
var _ stacks.Interface = (*Stack)(nil)
|
||||
}
|
||||
|
||||
type Stack struct {
|
||||
items []interface{}
|
||||
}
|
||||
|
||||
// Instantiates a new empty stack
|
||||
func New() *Stack {
|
||||
return &Stack{}
|
||||
}
|
||||
|
||||
// Pushes a value onto the top of the stack
|
||||
func (stack *Stack) Push(value interface{}) {
|
||||
stack.items = append(stack.items, value)
|
||||
}
|
||||
|
||||
// Pops (removes) top element on stack and returns it, or nil if stack is empty.
|
||||
// Second return parameter is true, unless the stack was empty and there was nothing to pop.
|
||||
func (stack *Stack) Pop() (value interface{}, ok bool) {
|
||||
size := len(stack.items)
|
||||
if size > 0 {
|
||||
value = stack.items[size-1]
|
||||
stack.items = append([]interface{}(nil), stack.items[:size-1]...)
|
||||
return value, true
|
||||
}
|
||||
return nil, false
|
||||
}
|
||||
|
||||
// Returns top element on the stack without removing it, or nil if stack is empty.
|
||||
// Second return parameter is true, unless the stack was empty and there was nothing to peek.
|
||||
func (stack *Stack) Peek() (value interface{}, ok bool) {
|
||||
size := len(stack.items)
|
||||
if size > 0 {
|
||||
return stack.items[size-1], true
|
||||
}
|
||||
return nil, false
|
||||
}
|
||||
|
||||
// Returns true if stack does not contain any elements.
|
||||
func (stack *Stack) Empty() bool {
|
||||
return len(stack.items) == 0
|
||||
}
|
||||
|
||||
// Returns number of elements within the stack.
|
||||
func (stack *Stack) Size() int {
|
||||
return len(stack.items)
|
||||
}
|
||||
|
||||
func (stack *Stack) String() string {
|
||||
str := "ArrayStack\n"
|
||||
values := []string{}
|
||||
for _, value := range stack.items {
|
||||
values = append(values, fmt.Sprintf("%v", value))
|
||||
}
|
||||
str += strings.Join(values, ", ")
|
||||
return str
|
||||
}
|
@ -0,0 +1,88 @@
|
||||
/*
|
||||
Copyright (c) Emir Pasic, All rights reserved.
|
||||
|
||||
This library is free software; you can redistribute it and/or
|
||||
modify it under the terms of the GNU Lesser General Public
|
||||
License as published by the Free Software Foundation; either
|
||||
version 3.0 of the License, or (at your option) any later version.
|
||||
|
||||
This library is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
Lesser General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU Lesser General Public
|
||||
License along with this library. See the file LICENSE included
|
||||
with this distribution for more information.
|
||||
*/
|
||||
|
||||
package arraystack
|
||||
|
||||
import (
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestArrayStack(t *testing.T) {
|
||||
|
||||
stack := New()
|
||||
|
||||
if actualValue := stack.Empty(); actualValue != true {
|
||||
t.Errorf("Got %v expected %v", actualValue, true)
|
||||
}
|
||||
|
||||
// insertions
|
||||
stack.Push(1)
|
||||
stack.Push(2)
|
||||
stack.Push(3)
|
||||
|
||||
if actualValue := stack.Empty(); actualValue != false {
|
||||
t.Errorf("Got %v expected %v", actualValue, false)
|
||||
}
|
||||
|
||||
if actualValue := stack.Size(); actualValue != 3 {
|
||||
t.Errorf("Got %v expected %v", actualValue, 3)
|
||||
}
|
||||
|
||||
if actualValue, ok := stack.Peek(); actualValue != 3 || !ok {
|
||||
t.Errorf("Got %v expected %v", actualValue, 3)
|
||||
}
|
||||
|
||||
stack.Pop()
|
||||
|
||||
if actualValue, ok := stack.Peek(); actualValue != 2 || !ok {
|
||||
t.Errorf("Got %v expected %v", actualValue, 2)
|
||||
}
|
||||
|
||||
if actualValue, ok := stack.Pop(); actualValue != 2 || !ok {
|
||||
t.Errorf("Got %v expected %v", actualValue, 2)
|
||||
}
|
||||
|
||||
if actualValue, ok := stack.Pop(); actualValue != 1 || !ok {
|
||||
t.Errorf("Got %v expected %v", actualValue, 1)
|
||||
}
|
||||
|
||||
if actualValue, ok := stack.Pop(); actualValue != nil || ok {
|
||||
t.Errorf("Got %v expected %v", actualValue, nil)
|
||||
}
|
||||
|
||||
if actualValue := stack.Empty(); actualValue != true {
|
||||
t.Errorf("Got %v expected %v", actualValue, true)
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
func BenchmarkArrayStack(b *testing.B) {
|
||||
// Slow in comparison to the LinkedListStack
|
||||
// BenchmarkArrayStack 50 31760994 ns/op 8540863 B/op 2010 allocs/op
|
||||
// BenchmarkLinkedListStack 5000 390812 ns/op 40016 B/op 2001 allocs/op
|
||||
for i := 0; i < b.N; i++ {
|
||||
stack := New()
|
||||
for n := 0; n < 1000; n++ {
|
||||
stack.Push(i)
|
||||
}
|
||||
for !stack.Empty() {
|
||||
stack.Pop()
|
||||
}
|
||||
}
|
||||
|
||||
}
|
Loading…
Reference in New Issue