Composite design pattern PHP example

In client code, and at it's very simplest it should read something like:

<?php
// Client code
 $int1 = new _Integer(2);
 $int2 = new _Integer(3);

 $operator = new Operator('+');

 $op1 = new Operands($int1);
 $op2 = new Operands($int2);

// $op1 + $operator + $op2 = Solution === 5

?>

However, we're attempting this using the composite design pattern and things soon become non-trivial. I have been working on the following:

<?php

// Use case: 2 + 3 = 5

// Component
interface Solution {
        function f();
}
// Composite
class Operands implements Solution {
        private $ints = [];
        function __construct(_Integer $_integer = null ){
                $this->_integer = $_integer; 
                array_push($this->ints, $this->_integer);
        }
        function f(){ /* Do nothing */ }

}
// Leaf
class _Integer implements Solution {
        private $_int;
        function __construct($_int){
                $this->_int = $_int;
        }
        function f(){ /* Do nothing */ }

        function getInt(){
                return $this->_int;
        }
}
// Leaf
class Operator implements Solution {
        private $operator;
        function __construct($operator){
            $valid = in_array($operator, ['+','-','/','*']);
            if($valid) $this->operator = $operator;
        }

        function f(){ /* Do nothing */ }
}

Ive reached a point where I need some help with Verbs and Nouns moreover the logic behind this great pattern - based around this simple equation.

Thanks in advance.