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<?php |
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namespace Riimu\Kit\BaseConversion; |
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/** |
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* Converts numbers by using a mathematical algorithm that relies on integers. |
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* |
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* DecimalConverter employs arbitrary-precision integer arithmetic to first |
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* convert the digits to decimal system and then to convert the digits to the |
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* target base. DecimalConverter depends on the GMP extension to perform the |
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* required arbitrary precision integer calculations. |
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* |
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* @author Riikka Kalliomäki <[email protected]> |
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* @copyright Copyright (c) 2014-2017 Riikka Kalliomäki |
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* @license http://opensource.org/licenses/mit-license.php MIT License |
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*/ |
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class DecimalConverter implements Converter |
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{ |
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/** @var int Precision for fraction conversions */ |
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private $precision; |
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/** @var NumberBase Number base used by provided numbers */ |
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private $source; |
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/** @var NumberBase Number base used by returned numbers */ |
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private $target; |
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/** @var string Number base used by GMP for standard conversions */ |
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private static $standardBase = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'; |
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/** |
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* Creates a new instance of DecimalConverter. |
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* @param NumberBase $source Number base used by the provided numbers |
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* @param NumberBase $target Number base used by the returned numbers |
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*/ |
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public function __construct(NumberBase $source, NumberBase $target) |
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{ |
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$this->precision = -1; |
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$this->source = $source; |
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$this->target = $target; |
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} |
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public function setPrecision($precision) |
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{ |
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$this->precision = (int) $precision; |
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} |
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public function convertInteger(array $number) |
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{ |
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$decimal = $this->getDecimal($number); |
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if ($this->isStandardBase($this->target->getDigitList())) { |
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return $this->target->canonizeDigits(str_split(gmp_strval($decimal, $this->target->getRadix()))); |
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} |
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$zero = gmp_init('0'); |
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$radix = gmp_init($this->target->getRadix()); |
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$result = []; |
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while (gmp_cmp($decimal, $zero) > 0) { |
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list($decimal, $modulo) = gmp_div_qr($decimal, $radix); |
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$result[] = gmp_intval($modulo); |
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} |
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return $this->target->getDigits(empty($result) ? [0] : array_reverse($result)); |
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} |
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public function convertFractions(array $number) |
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{ |
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$target = gmp_init($this->target->getRadix()); |
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$dividend = $this->getDecimal($number); |
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$divisor = $this->getDecimal( |
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[$this->source->getDigit(1)] + array_fill(1, max(count($number), 1), $this->source->getDigit(0)) |
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); |
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$digits = $this->getFractionDigitCount(count($number)); |
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$zero = gmp_init('0'); |
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$result = []; |
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for ($i = 0; $i < $digits && gmp_cmp($dividend, $zero) > 0; $i++) { |
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list($digit, $dividend) = gmp_div_qr(gmp_mul($dividend, $target), $divisor); |
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$result[] = gmp_intval($digit); |
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} |
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return $this->target->getDigits(empty($result) ? [0] : $result); |
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} |
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/** |
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* Converts the number from source base to a decimal GMP resource. |
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* @param array $number Digits for the number to convert |
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* @return resource resulting number as a GMP resource |
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*/ |
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private function getDecimal(array $number) |
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{ |
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if ($this->isStandardBase($this->source->getDigitList())) { |
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return gmp_init(implode('', $this->source->canonizeDigits($number)), $this->source->getRadix()); |
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} |
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$number = $this->source->getValues($number); |
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$decimal = gmp_init('0'); |
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$count = count($number); |
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$radix = gmp_init($this->source->getRadix()); |
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for ($i = 0; $i < $count; $i++) { |
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$decimal = gmp_add($decimal, gmp_mul(gmp_init($number[$i]), gmp_pow($radix, $count - $i - 1))); |
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} |
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return $decimal; |
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} |
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/** |
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* Tells if the list of digits match those used by GMP. |
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* @param array $digits List of digits for the number base |
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* @return bool True if the digits match, false if they do not |
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*/ |
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private function isStandardBase(array $digits) |
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{ |
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if (count($digits) > strlen(self::$standardBase)) { |
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return false; |
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} |
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return $digits === str_split(substr(self::$standardBase, 0, count($digits))); |
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} |
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/** |
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* Determines the number of digits required in the target base. |
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* @param int $count Number of digits in the original number |
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* @return int Number of digits required in the target base |
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*/ |
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private function getFractionDigitCount($count) |
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{ |
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if ($this->precision > 0) { |
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return $this->precision; |
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} |
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$target = gmp_init($this->target->getRadix()); |
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$maxFraction = gmp_pow(gmp_init($this->source->getRadix()), $count); |
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$digits = 1; |
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while (gmp_cmp(gmp_pow($target, $digits), $maxFraction) < 0) { |
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$digits++; |
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} |
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return $digits - $this->precision; |
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} |
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} |
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Riimu /
Kit-BaseConversion
This check compares the return type specified in the
@returnannotation of a function or method doc comment with the types returned by the function and raises an issue if they mismatch.