public function peek() { if ($this->_c === 0) { throw new TInvalidOperationException('stack_empty'); } else { return $this->_d[$this->_c - 1]; } }
public function testCanNotPeekAnEmptyStack() { $stack = new TStack(); try { $item = $stack->peek(); } catch (TInvalidOperationException $e) { return; } self::fail('An expected TInvalidOperationException was not raised'); }