Go Data Structures: Stack

// Package stack creates a ItemStack data structure for the Item type
package stack
import (
“sync”
<span style="color:#e6db74">"github.com/cheekybits/genny/generic"</span>
)
// Item the type of the stack
type Item generic.Type
// ItemStack the stack of Items
type ItemStack struct {
items []Item
lock  sync.RWMutex
}
// New creates a new ItemStack
func (s ItemStack) New() ItemStack {
s.items = []Item{}
return s
}
// Push adds an Item to the top of the stack
func (s *ItemStack) Push(t Item) {
s.lock.Lock()
s.items = append(s.items, t)
s.lock.Unlock()
}
// Pop removes an Item from the top of the stack
func (s ItemStack) Pop() Item {
s.lock.Lock()
item := s.items[len(s.items)-1]
s.items = s.items[0 : len(s.items)-1]
s.lock.Unlock()
return &item
}

package stack
import (
“testing”
)
var s ItemStack
func initStack() *ItemStack {
if s.items == nil {
s = ItemStack{}
s.New()
}
return &s
}
func TestPush(t *testing.T) {
s := initStack()
s.Push(1)
s.Push(2)
s.Push(3)
if size := len(s.items); size != 3 {
t.Errorf(“wrong count, expected 3 and got %d”, size)
}
}
func TestPop(t *testing.T) {
s.Pop()
if size := len(s.items); size != 2 {
t.Errorf(“wrong count, expected 2 and got %d”, size)
}
<span style="color:#a6e22e">s</span>.<span style="color:#a6e22e">Pop</span>()
<span style="color:#a6e22e">s</span>.<span style="color:#a6e22e">Pop</span>()
<span style="color:#66d9ef">if</span> <span style="color:#a6e22e">size</span> <span style="color:#f92672">:=</span> len(<span style="color:#a6e22e">s</span>.<span style="color:#a6e22e">items</span>); <span style="color:#a6e22e">size</span> <span style="color:#f92672">!=</span> <span style="color:#ae81ff">0</span> {
    <span style="color:#a6e22e">t</span>.<span style="color:#a6e22e">Errorf</span>(<span style="color:#e6db74">"wrong count, expected 0 and got %d"</span>, <span style="color:#a6e22e">size</span>)
}
}

//generate a `IntStack` stack of `int` values
genny -in stack.go -out stack-int.go gen "Item=int"
//generate a </span>StringStack<span style="color:#e6db74"> stack of </span>string<span style="color:#e6db74"> values
genny -in stack.go -out stack-string.go gen “Item=string”