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<?php declare(strict_types=1); |
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namespace DaveRandom\Resume; |
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final class RangeSet |
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{ |
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public const DEFAULT_MAX_RANGES = 10; |
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private const HEADER_PARSE_EXPR = /** @lang regex */ '/ |
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^ |
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\s* # tolerate lead white-space |
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(?<unit> [^\s=]+ ) # unit is everything up to first = or white-space |
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(?: \s*=\s* | \s+ ) # separator is = or white-space |
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(?<ranges> .+ ) # remainder is range spec |
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/x'; |
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private const RANGE_PARSE_EXPR = /** @lang regex */ '/ |
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^ |
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(?<start> [0-9]* ) # start is a decimal number |
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\s*-\s* # separator is a dash |
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(?<end> [0-9]* ) # end is a decimal number |
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$ |
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/x'; |
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/** |
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* The unit for ranges in the set |
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* |
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* @var string |
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*/ |
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private $unit; |
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/** |
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* The ranges in the set |
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* |
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* @var Range[] |
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*/ |
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private $ranges = []; |
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/** |
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* Parse an array of range specifiers into an array of Range objects |
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* |
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* @param string[] $ranges |
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* @return Range[] |
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*/ |
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private static function parseRanges(array $ranges): array |
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{ |
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$result = []; |
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foreach ($ranges as $i => $range) { |
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if (!\preg_match(self::RANGE_PARSE_EXPR, \trim($range), $match)) { |
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throw new InvalidRangeHeaderException("Invalid range format at position {$i}: Parse failure"); |
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} |
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if ($match['start'] === '' && $match['end'] === '') { |
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throw new InvalidRangeHeaderException("Invalid range format at position {$i}: Start and end empty"); |
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} |
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$result[] = $match['start'] === '' |
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? new Range(((int)$match['end']) * -1) |
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: new Range((int)$match['start'], $match['end'] !== '' ? (int)$match['end'] : null); |
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} |
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return $result; |
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} |
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/** |
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* Create a new instance from a Range header string |
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* |
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* @param string|null $header |
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* @param int $maxRanges |
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* @return self|null |
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*/ |
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public static function createFromHeader(?string $header, int $maxRanges = self::DEFAULT_MAX_RANGES): ?self |
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{ |
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if ($header === null) { |
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return null; |
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} |
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if (!\preg_match(self::HEADER_PARSE_EXPR, $header, $match)) { |
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throw new InvalidRangeHeaderException('Invalid header: Parse failure'); |
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} |
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$unit = $match['unit']; |
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$ranges = \explode(',', $match['ranges']); |
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if (\count($ranges) > $maxRanges) { |
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throw new InvalidRangeHeaderException("Invalid header: Too many ranges"); |
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} |
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return new self($unit, self::parseRanges($ranges)); |
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} |
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/** |
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* @param string $unit |
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* @param Range[] $ranges |
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*/ |
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public function __construct(string $unit, array $ranges) |
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{ |
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$this->unit = $unit; |
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$this->ranges = $ranges; |
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} |
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/** |
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* Get the unit for ranges in the set |
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* |
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* @return string |
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*/ |
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public function getUnit(): string |
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{ |
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return $this->unit; |
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} |
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/** |
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* Get a set of normalized ranges applied to a resource size |
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* |
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* @param int $size |
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* @return Range[] |
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*/ |
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public function getRangesForSize(int $size): array |
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{ |
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/** @var Range[] $ranges */ |
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$ranges = []; |
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foreach ($this->ranges as $range) { |
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try { |
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$range = $range->normalize($size); |
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if ($range->getStart() < $size) { |
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$ranges[] = $range; |
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} |
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} catch (UnsatisfiableRangeException $e) { |
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// ignore, other ranges in the set may be satisfiable |
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} |
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} |
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if (empty($ranges)) { |
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throw new UnsatisfiableRangeException('No specified ranges are satisfiable by a resource of the specified size'); |
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} |
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$previousCount = null; |
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$count = \count($ranges); |
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while ($count > 1 && $count !== $previousCount) { |
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\usort($ranges, static function(Range $a, Range $b) { |
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return $a->getStart() <=> $b->getStart(); |
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}); |
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$previousCount = $count; |
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for ($i = 0; $i < $count - 1; $i++) { |
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if ($ranges[$i]->overlaps($ranges[$i + 1])) { |
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$ranges[$i] = $ranges[$i]->combine($ranges[$i + 1]); |
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unset($ranges[$i + 1]); |
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break; |
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} |
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} |
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$count = \count($ranges); |
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} |
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return $ranges; |
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} |
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} |
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DaveRandom /
Resume
