ArrayList addition (inc. test, example and documentation)

README.md

@@ -152,6 +152,7 @@ All stacks implement the stack interface with the following methods:
 	Empty() bool
 	Size() int
 	Clear()
+	Values() []interface{}
 ```
 
 ####LinkedListStack
@@ -169,6 +170,7 @@ func main() {
 	stack := lls.New()  // empty
 	stack.Push(1)       // 1
 	stack.Push(2)       // 1, 2
+	stack.Values()      // 2, 1 (LIFO order)
 	_, _ = stack.Peek() // 2,true
 	_, _ = stack.Pop()  // 2, true
 	_, _ = stack.Pop()  // 1, true
@@ -183,7 +185,7 @@ func main() {
 
 ####ArrayStack
 
-This stack structure is based on a array.
+This stack structure is back by ArrayList.
 
 All operations are guaranted constant time performance.
 
@@ -196,6 +198,7 @@ func main() {
 	stack := arraystack.New() // empty
 	stack.Push(1)             // 1
 	stack.Push(2)             // 1, 2
+	stack.Values()            // 2, 1 (LIFO order)
 	_, _ = stack.Peek()       // 2,true
 	_, _ = stack.Pop()        // 2, true
 	_, _ = stack.Pop()        // 1, true

examples/arraystack.go

@@ -32,6 +32,7 @@ func ArrayStackExample() {
 	stack := arraystack.New() // empty
 	stack.Push(1)             // 1
 	stack.Push(2)             // 1, 2
+	stack.Values()            // 2, 1 (LIFO order)
 	_, _ = stack.Peek()       // 2,true
 	_, _ = stack.Pop()        // 2, true
 	_, _ = stack.Pop()        // 1, true

examples/linkedliststack.go

@@ -32,6 +32,7 @@ func LinkedListStackExample() {
 	stack := lls.New()  // empty
 	stack.Push(1)       // 1
 	stack.Push(2)       // 1, 2
+	stack.Values()      // 2, 1 (LIFO order)
 	_, _ = stack.Peek() // 2,true
 	_, _ = stack.Pop()  // 2, true
 	_, _ = stack.Pop()  // 1, true

stacks/arraystack/arraystack.go

@@ -24,7 +24,7 @@ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-// Implementation of stack using a slice.
+// Implementation of stack backed by ArrayList.
 // Structure is not thread safe.
 // References: http://en.wikipedia.org/wiki/Stack_%28abstract_data_type%29
 
@@ -32,6 +32,7 @@ package arraystack
 
 import (
 	"fmt"
+	"github.com/emirpasic/gods/lists/arraylist"
 	"github.com/emirpasic/gods/stacks"
 	"strings"
 )
@@ -41,64 +42,54 @@ func assertInterfaceImplementation() {
 }
 
 type Stack struct {
-	elements []interface{}
-	top      int
+	list *arraylist.List
 }
 
 // Instantiates a new empty stack
 func New() *Stack {
-	return &Stack{top: -1}
+	return &Stack{list: arraylist.New()}
 }
 
 // Pushes a value onto the top of the stack
 func (stack *Stack) Push(value interface{}) {
-	// Increase when capacity is reached by a factor of 1.5 and add one so it grows when size is zero
-	if stack.top+1 >= cap(stack.elements) {
-		currentSize := len(stack.elements)
-		sizeIncrease := int(1.5*float32(currentSize) + 1.0)
-		newSize := currentSize + sizeIncrease
-		newItems := make([]interface{}, newSize, newSize)
-		copy(newItems, stack.elements)
-		stack.elements = newItems
-	}
-	stack.top += 1
-	stack.elements[stack.top] = value
+	stack.list.Add(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) {
-	if stack.top >= 0 {
-		value, ok = stack.elements[stack.top], true
-		stack.top -= 1
-		return
-	}
-	return nil, false
+	return stack.list.Get(stack.list.Size() - 1)
 }
 
 // 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) {
-	if stack.top >= 0 {
-		return stack.elements[stack.top], true
-	}
-	return nil, false
+	return stack.list.Get(stack.list.Size() - 1)
 }
 
 // Returns true if stack does not contain any elements.
 func (stack *Stack) Empty() bool {
-	return stack.Size() == 0
+	return stack.list.Empty()
 }
 
 // Returns number of elements within the stack.
 func (stack *Stack) Size() int {
-	return stack.top + 1
+	return stack.list.Size()
 }
 
 // Removes all elements from the stack.
 func (stack *Stack) Clear() {
-	stack.top = -1
-	stack.elements = []interface{}{}
+	return 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)
+	}
+	return elements
 }
 
 func (stack *Stack) String() string {

stacks/arraystack/arraystack_test.go

@@ -27,6 +27,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 package arraystack
 
 import (
+	"github.com/emirpasic/gods/utils"
 	"testing"
 )
 
@@ -43,6 +44,10 @@ 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.Empty(); actualValue != false {
 		t.Errorf("Got %v expected %v", actualValue, false)
 	}
@@ -77,6 +82,10 @@ 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{}{})
+	}
+
 }
 
 func BenchmarkArrayStack(b *testing.B) {

stacks/linkedliststack/linkedliststack.go

@@ -98,6 +98,19 @@ func (stack *Stack) Clear() {
 	stack.size = 0
 }
 
+// Returns all elements in the stack (LIFO order).
+func (stack *Stack) Values() []interface{} {
+	size := stack.list.Size()
+	elements := make([]interface{}, size, size)
+	element := stack.top
+	for index := 0; element != nil; index++ {
+		elements[index] = element
+		element = element.next
+	}
+
+	return elements
+}
+
 func (stack *Stack) String() string {
 	str := "LinkedListStack\n"
 	element := stack.top

stacks/linkedliststack/linkedliststack_test.go

@@ -27,6 +27,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 package linkedliststack
 
 import (
+	"github.com/emirpasic/gods/utils"
 	"testing"
 )
 
@@ -43,6 +44,10 @@ 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.Empty(); actualValue != false {
 		t.Errorf("Got %v expected %v", actualValue, false)
 	}
@@ -77,6 +82,10 @@ 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{}{})
+	}
+
 }
 
 func BenchmarkLinkedListStack(b *testing.B) {

stacks/stacks.go

@@ -33,4 +33,5 @@ type Interface interface {
 	Empty() bool
 	Size() int
 	Clear()
+	Values() []interface{}
 }

utils/slices.go

@@ -0,0 +1,14 @@
+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
+}