<?php

class Timer
{
    public function __construct($name = '')
    {
        $this->name = $name;
        $this->micro = 0;
        $this->secondsFactor = 1000000;
        $this->millisecondsFactor = 1000;
    }

    private $name;
    private $micro;
    private $secondsFactor;
    private $millisecondsFactor;

    public function start()
    {
        $this->micro = microtime(true);
    }

    public function stop()
    {
        $this->micro = microtime(true) - $this->micro;
    }

    public function __toString()
    {
        return ($this->name ? $this->name . ': ' : '' ) . (string)($this->micro / $this->millisecondsFactor) . " ms";
    }
}