- make ArrayStack make use of our ArrayList

- add Values() method to stacks interface
- write tests

lists/arraylist/arraylist.go

@@ -82,7 +82,6 @@ func (list *List) Remove(index int) {
 		return
 	}
 
-	list.elements[index] = nil                                    // cleanup reference
 	copy(list.elements[index:], list.elements[index+1:list.size]) // shift to the left by one (slow operation, need ways to optimize this)
 	list.size -= 1
 

stacks/arraystack/arraystack.go

@@ -58,7 +58,9 @@ func (stack *Stack) Push(value interface{}) {
 // 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) {
-	return stack.list.Get(stack.list.Size() - 1)
+	value, ok = stack.list.Get(stack.list.Size() - 1)
+	stack.list.Remove(stack.list.Size() - 1)
+	return
 }
 
 // Returns top element on the stack without removing it, or nil if stack is empty.
@@ -79,15 +81,15 @@ func (stack *Stack) Size() int {
 
 // Removes all elements from the stack.
 func (stack *Stack) Clear() {
-	return stack.list.Clear()
+	stack.list.Clear()
 }
 
 // Returns all elements in the stack (LIFO order).
 func (stack *Stack) Values() []interface{} {
 	size := stack.list.Size()
 	elements := make([]interface{}, size, size)
-	for i := size - 1; i >= 0; i-- { // in reverse
-		elements[i] = stack.list.Get(i)
+	for i := 1; i <= size; i++ {
+		elements[size-i], _ = stack.list.Get(i - 1) // in reverse (LIFO)
 	}
 	return elements
 }
@@ -95,7 +97,7 @@ func (stack *Stack) Values() []interface{} {
 func (stack *Stack) String() string {
 	str := "ArrayStack\n"
 	values := []string{}
-	for _, value := range stack.elements {
+	for _, value := range stack.list.Values() {
 		values = append(values, fmt.Sprintf("%v", value))
 	}
 	str += strings.Join(values, ", ")

stacks/arraystack/arraystack_test.go

@@ -27,7 +27,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 package arraystack
 
 import (
-	"github.com/emirpasic/gods/utils"
 	"testing"
 )
 
@@ -44,8 +43,8 @@ func TestArrayStack(t *testing.T) {
 	stack.Push(2)
 	stack.Push(3)
 
-	if actualValue := stack.Values(); !utils.IdenticalSlices(actualValue, []interface{}{3, 2, 1}) {
-		t.Errorf("Got %v expected %v", actualValue, []interface{}{3, 2, 1})
+	if actualValue := stack.Values(); actualValue[0].(int) != 3 || actualValue[1].(int) != 2 || actualValue[2].(int) != 1 {
+		t.Errorf("Got %v expected %v", actualValue, "[3,2,1]")
 	}
 
 	if actualValue := stack.Empty(); actualValue != false {
@@ -82,8 +81,8 @@ func TestArrayStack(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, true)
 	}
 
-	if actualValue := stack.Values(); !utils.IdenticalSlices(actualValue, []interface{}{}) {
-		t.Errorf("Got %v expected %v", actualValue, []interface{}{})
+	if actualValue := stack.Values(); len(actualValue) != 0 {
+		t.Errorf("Got %v expected %v", actualValue, "[]")
 	}
 
 }

stacks/linkedliststack/linkedliststack.go

@@ -100,11 +100,10 @@ func (stack *Stack) Clear() {
 
 // Returns all elements in the stack (LIFO order).
 func (stack *Stack) Values() []interface{} {
-	size := stack.list.Size()
-	elements := make([]interface{}, size, size)
+	elements := make([]interface{}, stack.size, stack.size)
 	element := stack.top
 	for index := 0; element != nil; index++ {
-		elements[index] = element
+		elements[index] = element.value
 		element = element.next
 	}
 

stacks/linkedliststack/linkedliststack_test.go

@@ -27,7 +27,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 package linkedliststack
 
 import (
-	"github.com/emirpasic/gods/utils"
 	"testing"
 )
 
@@ -44,8 +43,8 @@ func TestLinkedListStack(t *testing.T) {
 	stack.Push(2)
 	stack.Push(3)
 
-	if actualValue := stack.Values(); !utils.IdenticalSlices(actualValue, []interface{}{3, 2, 1}) {
-		t.Errorf("Got %v expected %v", actualValue, []interface{}{3, 2, 1})
+	if actualValue := stack.Values(); actualValue[0].(int) != 3 || actualValue[1].(int) != 2 || actualValue[2].(int) != 1 {
+		t.Errorf("Got %v expected %v", actualValue, "[3,2,1]")
 	}
 
 	if actualValue := stack.Empty(); actualValue != false {
@@ -82,8 +81,8 @@ func TestLinkedListStack(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, true)
 	}
 
-	if actualValue := stack.Values(); !utils.IdenticalSlices(actualValue, []interface{}{}) {
-		t.Errorf("Got %v expected %v", actualValue, []interface{}{})
+	if actualValue := stack.Values(); len(actualValue) != 0 {
+		t.Errorf("Got %v expected %v", actualValue, "[]")
 	}
 
 }

utils/slices.go

@@ -1,14 +0,0 @@
-package utils
-
-// order and elements in the two slices have to match
-func IdenticalSlices(s1 []interface{}, s2 []interface{}) bool {
-	if len(s1) != len(s2) {
-		return false
-	}
-	for i := 0; i < len(s1); i++ {
-		if s1[i] != s2[i] {
-			return false
-		}
-	}
-	return true
-}