Composite design pattern PHP example -

in client code, , @ it's simplest should read 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 using composite design pattern , things become non-trivial. have been working on 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(){ /* nothing */ }  } // leaf class _integer implements solution {         private $_int;         function __construct($_int){                 $this->_int = $_int;         }         function f(){ /* 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(){ /* nothing */ } } 

ive reached point need verbs , nouns logic behind great pattern - based around simple equation.

thanks in advance.

edit: @peehaa. admittedly, not defined. ok, i'm trying apply composite pattern arithmetic expression say:

((3 + 4 - 1) * 5 + 6 * -7) / 2

                  '/'                 /     \               +        2            /     \          *         *        /   \     /   \       -     5   6     -7     /   \    +     1  /   \ 3     4 

for example, in php. first got idea from: https://sourcemaking.com/files/v2/content/patterns/composite_example1-2x.png

but struggling little , looking guidance.