import 'package:test/expect.dart';

import 'package:test/scaffolding.dart';

class ArrayStack<T> {

/// [stack]

List<T?> _stack = [];

/// [_count] is the number of element in the stack

int _count = 0;

/// [_size] of stack

int _size = 0;

//Init the array stack

ArrayStack(int size) {

this._size = size;

this._stack = List<T?>.filled(_size, null);

this._count = 0;

}

/// Push a item to the stack of type [T] to the [_stack]

/// if the size is exceeded the element wont be added.

void push(T item) {

if (_count == _size) {

return null;

}

_stack[_count] = item;

_count++;

}

/// Pop the last element inserted from the [_stack].

T? pop() {

if (_count == 0) {

return null;

}

T? pop_data = _stack[_count - 1];

_stack[_count - 1] = null;

_count--;

return pop_data;

}

List<T?> get stack {

return _stack;

}

}

void main() {

ArrayStack<String> arrayStack = new ArrayStack<String>(6);

arrayStack.push('1');

arrayStack.push("2");

arrayStack.push('3');

arrayStack.push("4");

arrayStack.push('5');

arrayStack.push("6");

test('test case 1', () {

expect(arrayStack.stack, ['1', '2', '3', '4', '5', '6']);

});

test('test case 2: pop stack', () {

expect('6', arrayStack.pop());

});

test('test case 3: pop stack', () {

expect('5', arrayStack.pop());

});

test('test case 4: pop stack', () {

expect('4', arrayStack.pop());

});

test('test case 5: pop stack', () {

expect('3', arrayStack.pop());

});

test('test case 6: pop stack', () {

expect('2', arrayStack.pop());

});

test('test case 7: pop stack', () {

expect('1', arrayStack.pop());

});

test('test case 8: pop stack', () {

expect(null, arrayStack.pop());

});

ArrayStack<String> arrayStack2 = new ArrayStack<String>(3);

test('test case 9', () {

expect(arrayStack2.stack, [null, null, null]);

});

}