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<?php namespace Mbh\Iterator; |
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/** |
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* MBHFramework |
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* |
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* @link https://github.com/MBHFramework/mbh-framework |
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* @copyright Copyright (c) 2017 Ulises Jeremias Cornejo Fandos |
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* @license https://github.com/MBHFramework/mbh-framework/blob/master/LICENSE (MIT License) |
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*/ |
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use ArrayAccess; |
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use LimitIterator; |
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use JsonSerializable; |
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use Countable; |
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use Iterator; |
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use InvalidArgumentException; |
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use RuntimeException; |
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/** |
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* Iterator to allow a slice to be used like an array |
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*/ |
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class SliceIterator extends LimitIterator implements ArrayAccess, Countable, JsonSerializable |
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{ |
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protected $count = 0; |
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protected $begin = 0; |
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const INVALID_INDEX = 'Index invalid or out of range'; |
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/** |
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* Build an iterator over a slice of an ArrayAccess object |
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* Unlike a LimitIterator, the $end defines the last index, not the count |
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* |
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* @param Iterator $iterator An ArrayAccess iterator, e.g. SplFixedArray |
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* @param int $begin The starting offset of the slice |
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* @param int $end The last index of the slice |
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*/ |
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public function __construct(Iterator $iterator, $begin = 0, $end = null) |
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{ |
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if ($iterator instanceof ArrayAccess && $iterator instanceof Countable) { |
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$count = count($iterator); |
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// Negative begin means start from the end |
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if ($begin < 0) { |
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$begin = max(0, $count + $begin); |
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} |
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// If no end set, assume whole array |
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if ($end === null) { |
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$end = $count; |
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} elseif ($end < 0) { |
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// Ends counting back from start |
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$end = max($begin, $count + $end); |
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} |
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// Set the size of iterable object, for quick-lookup |
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$this->count = max(0, $end - $begin); |
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// Need to store the starting offset to adjust by |
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$this->begin = $begin; |
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// Init as LimitIterator |
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parent::__construct($iterator, $this->begin, $this->count); |
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} else { |
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throw new InvalidArgumentException('Iterator must be a Countable ArrayAccess'); |
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} |
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} |
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/** |
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* Rewind, extended for clean results on empty sets |
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*/ |
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public function rewind() |
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{ |
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// no need to rewind on empty sets |
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if ($this->count > 0) { |
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parent::rewind(); |
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} |
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} |
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/** |
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* Countable |
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*/ |
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public function count(): int |
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{ |
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return $this->count; |
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} |
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/** |
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* ArrayAccess |
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*/ |
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public function offsetExists($offset) |
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{ |
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return $offset >= 0 && $offset < $this->count; |
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} |
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public function offsetGet($offset) |
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{ |
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if ($this->offsetExists($offset)) { |
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return $this->getInnerIterator()->offsetGet($offset + $this->begin); |
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} else { |
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throw new RuntimeException(self::INVALID_INDEX); |
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} |
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} |
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public function offsetSet($offset, $value) |
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{ |
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return $this->getInnerIterator()->offsetSet($offset + $this->begin, $value); |
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} |
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public function offsetUnset($offset) |
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{ |
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return $this->getInnerIterator()->offsetUnset($offset + $this->begin); |
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} |
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/** |
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* JsonSerializable |
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*/ |
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public function jsonSerialize() |
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{ |
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return $this->toArray(); |
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} |
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public function toArray() |
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{ |
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return iterator_to_array($this, false); |
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} |
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} |
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MBHFramework /
structures
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