Subversion-Projekte lars-tiefland.laravel_shop

<?php

declare(strict_types=1);

namespace Brick\Math\Internal;

use Brick\Math\Exception\RoundingNecessaryException;

use Brick\Math\RoundingMode;

/**

 * Performs basic operations on arbitrary size integers.

 *

 * Unless otherwise specified, all parameters must be validated as non-empty strings of digits,

 * without leading zero, and with an optional leading minus sign if the number is not zero.

 *

 * Any other parameter format will lead to undefined behaviour.

 * All methods must return strings respecting this format, unless specified otherwise.

 *

 * @internal

 *

 * @psalm-immutable

 */

abstract class Calculator

{

    /**

     * The maximum exponent value allowed for the pow() method.

     */

    public const MAX_POWER = 1000000;

    /**

     * The alphabet for converting from and to base 2 to 36, lowercase.

     */

    public const ALPHABET = '0123456789abcdefghijklmnopqrstuvwxyz';

    /**

     * The Calculator instance in use.

     */

    private static ?Calculator $instance = null;

    /**

     * Sets the Calculator instance to use.

     *

     * An instance is typically set only in unit tests: the autodetect is usually the best option.

     *

     * @param Calculator|null $calculator The calculator instance, or NULL to revert to autodetect.

     */

    final public static function set(?Calculator $calculator) : void

    {

        self::$instance = $calculator;

    }

    /**

     * Returns the Calculator instance to use.

     *

     * If none has been explicitly set, the fastest available implementation will be returned.

     *

     * @psalm-pure

     * @psalm-suppress ImpureStaticProperty

     */

    final public static function get() : Calculator

    {

        if (self::$instance === null) {

            /** @psalm-suppress ImpureMethodCall */

            self::$instance = self::detect();

        }

        return self::$instance;

    }

    /**

     * Returns the fastest available Calculator implementation.

     *

     * @codeCoverageIgnore

     */

    private static function detect() : Calculator

    {

        if (\extension_loaded('gmp')) {

            return new Calculator\GmpCalculator();

        }

        if (\extension_loaded('bcmath')) {

            return new Calculator\BcMathCalculator();

        }

        return new Calculator\NativeCalculator();

    }

    /**

     * Extracts the sign & digits of the operands.

     *

     * @return array{bool, bool, string, string} Whether $a and $b are negative, followed by their digits.

     */

    final protected function init(string $a, string $b) : array

    {

        return [

            $aNeg = ($a[0] === '-'),

            $bNeg = ($b[0] === '-'),

            $aNeg ? \substr($a, 1) : $a,

            $bNeg ? \substr($b, 1) : $b,

        ];

    }

    /**

     * Returns the absolute value of a number.

     */

    final public function abs(string $n) : string

    {

        return ($n[0] === '-') ? \substr($n, 1) : $n;

    }

    /**

     * Negates a number.

     */

    final public function neg(string $n) : string

    {

        if ($n === '0') {

            return '0';

        }

        if ($n[0] === '-') {

            return \substr($n, 1);

        }

        return '-' . $n;

    }

    /**

     * Compares two numbers.

     *

     * @return int [-1, 0, 1] If the first number is less than, equal to, or greater than the second number.

     */

    final public function cmp(string $a, string $b) : int

    {

        [$aNeg, $bNeg, $aDig, $bDig] = $this->init($a, $b);

        if ($aNeg && ! $bNeg) {

            return -1;

        }

        if ($bNeg && ! $aNeg) {

            return 1;

        }

        $aLen = \strlen($aDig);

        $bLen = \strlen($bDig);

        if ($aLen < $bLen) {

            $result = -1;

        } elseif ($aLen > $bLen) {

            $result = 1;

        } else {

            $result = $aDig <=> $bDig;

        }

        return $aNeg ? -$result : $result;

    }

    /**

     * Adds two numbers.

     */

    abstract public function add(string $a, string $b) : string;

    /**

     * Subtracts two numbers.

     */

    abstract public function sub(string $a, string $b) : string;

    /**

     * Multiplies two numbers.

     */

    abstract public function mul(string $a, string $b) : string;

    /**

     * Returns the quotient of the division of two numbers.

     *

     * @param string $a The dividend.

     * @param string $b The divisor, must not be zero.

     *

     * @return string The quotient.

     */

    abstract public function divQ(string $a, string $b) : string;

    /**

     * Returns the remainder of the division of two numbers.

     *

     * @param string $a The dividend.

     * @param string $b The divisor, must not be zero.

     *

     * @return string The remainder.

     */

    abstract public function divR(string $a, string $b) : string;

    /**

     * Returns the quotient and remainder of the division of two numbers.

     *

     * @param string $a The dividend.

     * @param string $b The divisor, must not be zero.

     *

     * @return array{string, string} An array containing the quotient and remainder.

     */

    abstract public function divQR(string $a, string $b) : array;

    /**

     * Exponentiates a number.

     *

     * @param string $a The base number.

     * @param int    $e The exponent, validated as an integer between 0 and MAX_POWER.

     *

     * @return string The power.

     */

    abstract public function pow(string $a, int $e) : string;

    /**

     * @param string $b The modulus; must not be zero.

     */

    public function mod(string $a, string $b) : string

    {

        return $this->divR($this->add($this->divR($a, $b), $b), $b);

    }

    /**

     * Returns the modular multiplicative inverse of $x modulo $m.

     *

     * If $x has no multiplicative inverse mod m, this method must return null.

     *

     * This method can be overridden by the concrete implementation if the underlying library has built-in support.

     *

     * @param string $m The modulus; must not be negative or zero.

     */

    public function modInverse(string $x, string $m) : ?string

    {

        if ($m === '1') {

            return '0';

        }

        $modVal = $x;

        if ($x[0] === '-' || ($this->cmp($this->abs($x), $m) >= 0)) {

            $modVal = $this->mod($x, $m);

        }

        [$g, $x] = $this->gcdExtended($modVal, $m);

        if ($g !== '1') {

            return null;

        }

        return $this->mod($this->add($this->mod($x, $m), $m), $m);

    }

    /**

     * Raises a number into power with modulo.

     *

     * @param string $base The base number; must be positive or zero.

     * @param string $exp  The exponent; must be positive or zero.

     * @param string $mod  The modulus; must be strictly positive.

     */

    abstract public function modPow(string $base, string $exp, string $mod) : string;

    /**

     * Returns the greatest common divisor of the two numbers.

     *

     * This method can be overridden by the concrete implementation if the underlying library

     * has built-in support for GCD calculations.

     *

     * @return string The GCD, always positive, or zero if both arguments are zero.

     */

    public function gcd(string $a, string $b) : string

    {

        if ($a === '0') {

            return $this->abs($b);

        }

        if ($b === '0') {

            return $this->abs($a);

        }

        return $this->gcd($b, $this->divR($a, $b));

    }

    /**

     * @return array{string, string, string} GCD, X, Y

     */

    private function gcdExtended(string $a, string $b) : array

    {

        if ($a === '0') {

            return [$b, '0', '1'];

        }

        [$gcd, $x1, $y1] = $this->gcdExtended($this->mod($b, $a), $a);

        $x = $this->sub($y1, $this->mul($this->divQ($b, $a), $x1));

        $y = $x1;

        return [$gcd, $x, $y];

    }

    /**

     * Returns the square root of the given number, rounded down.

     *

     * The result is the largest x such that x² ≤ n.

     * The input MUST NOT be negative.

     */

    abstract public function sqrt(string $n) : string;

    /**

     * Converts a number from an arbitrary base.

     *

     * This method can be overridden by the concrete implementation if the underlying library

     * has built-in support for base conversion.

     *

     * @param string $number The number, positive or zero, non-empty, case-insensitively validated for the given base.

     * @param int    $base   The base of the number, validated from 2 to 36.

     *

     * @return string The converted number, following the Calculator conventions.

     */

    public function fromBase(string $number, int $base) : string

    {

        return $this->fromArbitraryBase(\strtolower($number), self::ALPHABET, $base);

    }

    /**

     * Converts a number to an arbitrary base.

     *

     * This method can be overridden by the concrete implementation if the underlying library

     * has built-in support for base conversion.

     *

     * @param string $number The number to convert, following the Calculator conventions.

     * @param int    $base   The base to convert to, validated from 2 to 36.

     *

     * @return string The converted number, lowercase.

     */

    public function toBase(string $number, int $base) : string

    {

        $negative = ($number[0] === '-');

        if ($negative) {

            $number = \substr($number, 1);

        }

        $number = $this->toArbitraryBase($number, self::ALPHABET, $base);

        if ($negative) {

            return '-' . $number;

        }

        return $number;

    }

    /**

     * Converts a non-negative number in an arbitrary base using a custom alphabet, to base 10.

     *

     * @param string $number   The number to convert, validated as a non-empty string,

     *                         containing only chars in the given alphabet/base.

     * @param string $alphabet The alphabet that contains every digit, validated as 2 chars minimum.

     * @param int    $base     The base of the number, validated from 2 to alphabet length.

     *

     * @return string The number in base 10, following the Calculator conventions.

     */

    final public function fromArbitraryBase(string $number, string $alphabet, int $base) : string

    {

        // remove leading "zeros"

        $number = \ltrim($number, $alphabet[0]);

        if ($number === '') {

            return '0';

        }

        // optimize for "one"

        if ($number === $alphabet[1]) {

            return '1';

        }

        $result = '0';

        $power = '1';

        $base = (string) $base;

        for ($i = \strlen($number) - 1; $i >= 0; $i--) {

            $index = \strpos($alphabet, $number[$i]);

            if ($index !== 0) {

                $result = $this->add($result, ($index === 1)

                    ? $power

                    : $this->mul($power, (string) $index)

                );

            }

            if ($i !== 0) {

                $power = $this->mul($power, $base);

            }

        }

        return $result;

    }

    /**

     * Converts a non-negative number to an arbitrary base using a custom alphabet.

     *

     * @param string $number   The number to convert, positive or zero, following the Calculator conventions.

     * @param string $alphabet The alphabet that contains every digit, validated as 2 chars minimum.

     * @param int    $base     The base to convert to, validated from 2 to alphabet length.

     *

     * @return string The converted number in the given alphabet.

     */

    final public function toArbitraryBase(string $number, string $alphabet, int $base) : string

    {

        if ($number === '0') {

            return $alphabet[0];

        }

        $base = (string) $base;

        $result = '';

        while ($number !== '0') {

            [$number, $remainder] = $this->divQR($number, $base);

            $remainder = (int) $remainder;

            $result .= $alphabet[$remainder];

        }

        return \strrev($result);

    }

    /**

     * Performs a rounded division.

     *

     * Rounding is performed when the remainder of the division is not zero.

     *

     * @param string $a            The dividend.

     * @param string $b            The divisor, must not be zero.

     * @param int    $roundingMode The rounding mode.

     *

     * @throws \InvalidArgumentException  If the rounding mode is invalid.

     * @throws RoundingNecessaryException If RoundingMode::UNNECESSARY is provided but rounding is necessary.

     *

     * @psalm-suppress ImpureFunctionCall

     */

    final public function divRound(string $a, string $b, int $roundingMode) : string

    {

        [$quotient, $remainder] = $this->divQR($a, $b);

        $hasDiscardedFraction = ($remainder !== '0');

        $isPositiveOrZero = ($a[0] === '-') === ($b[0] === '-');

        $discardedFractionSign = function() use ($remainder, $b) : int {

            $r = $this->abs($this->mul($remainder, '2'));

            $b = $this->abs($b);

            return $this->cmp($r, $b);

        };

        $increment = false;

        switch ($roundingMode) {

            case RoundingMode::UNNECESSARY:

                if ($hasDiscardedFraction) {

                    throw RoundingNecessaryException::roundingNecessary();

                }

                break;

            case RoundingMode::UP:

                $increment = $hasDiscardedFraction;

                break;

            case RoundingMode::DOWN:

                break;

            case RoundingMode::CEILING:

                $increment = $hasDiscardedFraction && $isPositiveOrZero;

                break;

            case RoundingMode::FLOOR:

                $increment = $hasDiscardedFraction && ! $isPositiveOrZero;

                break;

            case RoundingMode::HALF_UP:

                $increment = $discardedFractionSign() >= 0;

                break;

            case RoundingMode::HALF_DOWN:

                $increment = $discardedFractionSign() > 0;

                break;

            case RoundingMode::HALF_CEILING:

                $increment = $isPositiveOrZero ? $discardedFractionSign() >= 0 : $discardedFractionSign() > 0;

                break;

            case RoundingMode::HALF_FLOOR:

                $increment = $isPositiveOrZero ? $discardedFractionSign() > 0 : $discardedFractionSign() >= 0;

                break;

            case RoundingMode::HALF_EVEN:

                $lastDigit = (int) $quotient[-1];

                $lastDigitIsEven = ($lastDigit % 2 === 0);

                $increment = $lastDigitIsEven ? $discardedFractionSign() > 0 : $discardedFractionSign() >= 0;

                break;

            default:

                throw new \InvalidArgumentException('Invalid rounding mode.');

        }

        if ($increment) {

            return $this->add($quotient, $isPositiveOrZero ? '1' : '-1');

        }

        return $quotient;

    }

    /**

     * Calculates bitwise AND of two numbers.

     *

     * This method can be overridden by the concrete implementation if the underlying library

     * has built-in support for bitwise operations.

     */

    public function and(string $a, string $b) : string

    {

        return $this->bitwise('and', $a, $b);

    }

    /**

     * Calculates bitwise OR of two numbers.

     *

     * This method can be overridden by the concrete implementation if the underlying library

     * has built-in support for bitwise operations.

     */

    public function or(string $a, string $b) : string

    {

        return $this->bitwise('or', $a, $b);

    }

    /**

     * Calculates bitwise XOR of two numbers.

     *

     * This method can be overridden by the concrete implementation if the underlying library

     * has built-in support for bitwise operations.

     */

    public function xor(string $a, string $b) : string

    {

        return $this->bitwise('xor', $a, $b);

    }

    /**

     * Performs a bitwise operation on a decimal number.

     *

     * @param 'and'|'or'|'xor' $operator The operator to use.

     * @param string           $a        The left operand.

     * @param string           $b        The right operand.

     */

    private function bitwise(string $operator, string $a, string $b) : string

    {

        [$aNeg, $bNeg, $aDig, $bDig] = $this->init($a, $b);

        $aBin = $this->toBinary($aDig);

        $bBin = $this->toBinary($bDig);

        $aLen = \strlen($aBin);

        $bLen = \strlen($bBin);

        if ($aLen > $bLen) {

            $bBin = \str_repeat("\x00", $aLen - $bLen) . $bBin;

        } elseif ($bLen > $aLen) {

            $aBin = \str_repeat("\x00", $bLen - $aLen) . $aBin;

        }

        if ($aNeg) {

            $aBin = $this->twosComplement($aBin);

        }

        if ($bNeg) {

            $bBin = $this->twosComplement($bBin);

        }

        switch ($operator) {

            case 'and':

                $value = $aBin & $bBin;

                $negative = ($aNeg and $bNeg);

                break;

            case 'or':

                $value = $aBin | $bBin;

                $negative = ($aNeg or $bNeg);

                break;

            case 'xor':

                $value = $aBin ^ $bBin;

                $negative = ($aNeg xor $bNeg);

                break;

            // @codeCoverageIgnoreStart

            default:

                throw new \InvalidArgumentException('Invalid bitwise operator.');

            // @codeCoverageIgnoreEnd

        }

        if ($negative) {

            $value = $this->twosComplement($value);

        }

        $result = $this->toDecimal($value);

        return $negative ? $this->neg($result) : $result;

    }

    /**

     * @param string $number A positive, binary number.

     */

    private function twosComplement(string $number) : string

    {

        $xor = \str_repeat("\xff", \strlen($number));

        $number ^= $xor;

        for ($i = \strlen($number) - 1; $i >= 0; $i--) {

            $byte = \ord($number[$i]);

            if (++$byte !== 256) {

                $number[$i] = \chr($byte);

                break;

            }

            $number[$i] = "\x00";

            if ($i === 0) {

                $number = "\x01" . $number;

            }

        }

        return $number;

    }

    /**

     * Converts a decimal number to a binary string.

     *

     * @param string $number The number to convert, positive or zero, only digits.

     */

    private function toBinary(string $number) : string

    {

        $result = '';

        while ($number !== '0') {

            [$number, $remainder] = $this->divQR($number, '256');

            $result .= \chr((int) $remainder);

        }

        return \strrev($result);

    }

    /**

     * Returns the positive decimal representation of a binary number.

     *

     * @param string $bytes The bytes representing the number.

     */

    private function toDecimal(string $bytes) : string

    {

        $result = '0';

        $power = '1';

        for ($i = \strlen($bytes) - 1; $i >= 0; $i--) {

            $index = \ord($bytes[$i]);

            if ($index !== 0) {

                $result = $this->add($result, ($index === 1)

                    ? $power

                    : $this->mul($power, (string) $index)

                );

            }

            if ($i !== 0) {

                $power = $this->mul($power, '256');

            }

        }

        return $result;

    }

}