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- <?php
- namespace Drupal\Component\Utility;
- /**
- * Provides helper methods for manipulating numbers.
- *
- * @ingroup utility
- */
- class Number {
- /**
- * Verifies that a number is a multiple of a given step.
- *
- * The implementation assumes it is dealing with IEEE 754 double precision
- * floating point numbers that are used by PHP on most systems.
- *
- * This is based on the number/range verification methods of webkit.
- *
- * @param float $value
- * The value that needs to be checked.
- * @param float $step
- * The step scale factor. Must be positive.
- * @param float $offset
- * (optional) An offset, to which the difference must be a multiple of the
- * given step.
- *
- * @return bool
- * TRUE if no step mismatch has occurred, or FALSE otherwise.
- *
- * @see http://opensource.apple.com/source/WebCore/WebCore-1298/html/NumberInputType.cpp
- */
- public static function validStep($value, $step, $offset = 0.0) {
- $double_value = (double) abs($value - $offset);
- // The fractional part of a double has 53 bits. The greatest number that
- // could be represented with that is 2^53. If the given value is even bigger
- // than $step * 2^53, then dividing by $step will result in a very small
- // remainder. Since that remainder can't even be represented with a single
- // precision float the following computation of the remainder makes no sense
- // and we can safely ignore it instead.
- if ($double_value / pow(2.0, 53) > $step) {
- return TRUE;
- }
- // Now compute that remainder of a division by $step.
- $remainder = (double) abs($double_value - $step * round($double_value / $step));
- // $remainder is a double precision floating point number. Remainders that
- // can't be represented with single precision floats are acceptable. The
- // fractional part of a float has 24 bits. That means remainders smaller than
- // $step * 2^-24 are acceptable.
- $computed_acceptable_error = (double) ($step / pow(2.0, 24));
- return $computed_acceptable_error >= $remainder || $remainder >= ($step - $computed_acceptable_error);
- }
- /**
- * Generates a sorting code from an integer.
- *
- * Consists of a leading character indicating length, followed by N digits
- * with a numerical value in base 36 (alphadecimal). These codes can be sorted
- * as strings without altering numerical order.
- *
- * It goes:
- * 00, 01, 02, ..., 0y, 0z,
- * 110, 111, ... , 1zy, 1zz,
- * 2100, 2101, ..., 2zzy, 2zzz,
- * 31000, 31001, ...
- *
- * @param int $i
- * The integer value to convert.
- *
- * @return string
- * The alpha decimal value.
- *
- * @see \Drupal\Component\Utility\Number::alphadecimalToInt
- */
- public static function intToAlphadecimal($i = 0) {
- $num = base_convert((int) $i, 10, 36);
- $length = strlen($num);
- return chr($length + ord('0') - 1) . $num;
- }
- /**
- * Decodes a sorting code back to an integer.
- *
- * @param string $string
- * The alpha decimal value to convert
- *
- * @return int
- * The integer value.
- *
- * @see \Drupal\Component\Utility\Number::intToAlphadecimal
- */
- public static function alphadecimalToInt($string = '00') {
- return (int) base_convert(substr($string, 1), 36, 10);
- }
- }
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