<?php
/*
* This file is part of the PHPASN1 library.
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace FG\Utility;
/**
* Class BigInteger
* Utility class to remove dependence on a single large number library. Not intended for external use, this class only
* implements the functionality needed throughout this project.
*
* Instances are immutable, all operations return a new instance with the result.
*
* @package FG\Utility
* @internal
*/
abstract class BigInteger
{
/**
* Force a preference on the underlying big number implementation, useful for testing.
* @var string|null
*/
private static $_prefer;
public static function setPrefer($prefer = null)
{
self::$_prefer = $prefer;
}
/**
* Create a BigInteger instance based off the base 10 string or an integer.
* @param string|int $val
* @return BigInteger
* @throws \InvalidArgumentException
*/
public static function create($val)
{
if (self::$_prefer) {
switch (self::$_prefer) {
case 'gmp':
$ret = new BigIntegerGmp();
break;
case 'bcmath':
$ret = new BigIntegerBcmath();
break;
default:
throw new \UnexpectedValueException('Unknown number implementation: ' . self::$_prefer);
}
}
else {
// autodetect
if (function_exists('gmp_add')) {
$ret = new BigIntegerGmp();
}
elseif (function_exists('bcadd')) {
$ret = new BigIntegerBcmath();
} else {
throw new \RuntimeException('Requires GMP or bcmath extension.');
}
}
if (is_int($val)) {
$ret->_fromInteger($val);
}
else {
// convert to string, if not already one
$val = (string)$val;
// validate string
if (!preg_match('/^-?[0-9]+$/', $val)) {
throw new \InvalidArgumentException('Expects a string representation of an integer.');
}
$ret->_fromString($val);
}
return $ret;
}
/**
* BigInteger constructor.
* Prevent directly instantiating object, use BigInteger::create instead.
*/
protected function __construct()
{
}
/**
* Subclasses must provide clone functionality.
* @return BigInteger
*/
abstract public function __clone();
/**
* Assign the instance value from base 10 string.
* @param string $str
*/
abstract protected function _fromString($str);
/**
* Assign the instance value from an integer type.
* @param int $integer
*/
abstract protected function _fromInteger($integer);
/**
* Must provide string implementation that returns base 10 number.
* @return string
*/
abstract public function __toString();
/* INFORMATIONAL FUNCTIONS */
/**
* Return integer, if possible. Throws an exception if the number can not be represented as a native integer.
* @return int
* @throws \OverflowException
*/
abstract public function toInteger();
/**
* Is represented integer negative?
* @return bool
*/
abstract public function isNegative();
/**
* Compare the integer with $number, returns a negative integer if $this is less than number, returns 0 if $this is
* equal to number and returns a positive integer if $this is greater than number.
* @param BigInteger|string|int $number
* @return int
*/
abstract public function compare($number);
/* MODIFY */
/**
* Add another integer $b and returns the result.
* @param BigInteger|string|int $b
* @return BigInteger
*/
abstract public function add($b);
/**
* Subtract $b from $this and returns the result.
* @param BigInteger|string|int $b
* @return BigInteger
*/
abstract public function subtract($b);
/**
* Multiply value.
* @param BigInteger|string|int $b
* @return BigInteger
*/
abstract public function multiply($b);
/**
* The value $this modulus $b.
* @param BigInteger|string|int $b
* @return BigInteger
*/
abstract public function modulus($b);
/**
* Raise $this to the power of $b and returns the result.
* @param BigInteger|string|int $b
* @return BigInteger
*/
abstract public function toPower($b);
/**
* Shift the value to the right by a set number of bits and returns the result.
* @param int $bits
* @return BigInteger
*/
abstract public function shiftRight($bits = 8);
/**
* Shift the value to the left by a set number of bits and returns the result.
* @param int $bits
* @return BigInteger
*/
abstract public function shiftLeft($bits = 8);
/**
* Returns the absolute value.
* @return BigInteger
*/
abstract public function absoluteValue();
}