<?php
/**
* Immutable class for handling numbers with precision.
*
* Never change the $number or the $precision after the creation of the object.
*/
class DecimalNumber {
private $precision;
private $number;
public function __construct() {
return $this;
}
/**
* Get an instance given a string and a precision
* @param string $string The decimal number in string form
* @param int $precision The precision of the number
* @return DecimalNumber Return new instance
*/
public static function get($string, $precision = 4) {
$number = static::_get($string, $precision);
$number->number = bcadd($string, '0', $precision);
return $number;
}
private static function _get($string, $precision) {
$me = get_called_class();
$number = new $me;
$number->precision = $precision;
$number->number = $string;
return $number;
}
/**
* Add a formal entry point for decimal numbers
* @param DecimalNumber $number Decimal number to base off of
* @param integer $precision new precision
* @return DecimalNumber DecimalNumber with new precision
*/
public static function decimalNumber(DecimalNumber $number, $precision = 4) {
if ($number->precision === $precision) return clone $number;
return static::get($number, $precision);
}
/**
* Perform an addition operation
* @param DecimalNumber $number Addend
* @return DecimalNumber Sum
*/
public function sum(DecimalNumber $number) {
return DecimalNumber::_get(bcadd($this->number, $number, $this->precision), $this->precision);
}
/**
* Perform a subtraction operation
* @param DecimalNumber $number Addend
* @return DecimalNumber Sum
*/
public function difference(DecimalNumber $number) {
return DecimalNumber::_get(bcsub($this->number, $number, $this->precision), $this->precision);
}
/**
* Perform a multiplication operation
* @param DecimalNumber $number Multiplier
* @return DecimalNumber Product
*/
public function product(DecimalNumber $number) {
return DecimalNumber::_get(bcmul($this->number, $number, $this->precision), $this->precision);
}
/**
* Perform a division operation
* @param DecimalNumber $number Divisor
* @return DecimalNumber Quotient
*/
public function quotient(DecimalNumber $number) {
return DecimalNumber::_get(bcdiv($this->number, $number, $this->precision), $this->precision);
}
public function floored() {
return DecimalNumber::_get(bcadd(bcadd($this->number, '0'), '0', $this->precision), $this->precision);
}
/**
* Automagically convert to a string
* @return string returns a string containing the value of this DecimalNumber
*/
public function __toString() {
return $this->number;
}
}
$a = DecimalNumber::get('.7');
$b = DecimalNumber::get('.1');
$c = $a->sum($b);
$d = $c->product(DecimalNumber::get('10.2'))->floored();
echo $d;