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<?php namespace Mbh\Collection\Traits; |
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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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trait Capacity |
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{ |
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/** |
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* @var integer internal capacity |
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*/ |
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protected $capacity = self::MIN_CAPACITY; |
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/** |
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* @inheritDoc |
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*/ |
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public function capacity(): int |
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{ |
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return $this->capacity; |
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} |
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/** |
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* @inheritDoc |
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*/ |
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public function allocate(int $capacity) |
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{ |
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return $this->setSize($this->capacity = max($capacity, $this->capacity)); |
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} |
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/** |
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* @return float The structures growth factor. |
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*/ |
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protected function getGrowthFactor(): float |
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{ |
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return 2; |
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} |
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/** |
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* @return float to multiply by when decreasing capacity. |
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*/ |
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protected function getDecayFactor(): float |
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{ |
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return 0.5; |
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} |
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/** |
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* @return float The ratio between size and capacity when capacity should be |
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* decreased. |
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*/ |
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protected function getTruncateThreshold(): float |
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{ |
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return 0.25; |
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} |
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/** |
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* Checks and adjusts capacity if required. |
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*/ |
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protected function checkCapacity() |
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{ |
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if ($this->shouldIncreaseCapacity()) { |
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$this->increaseCapacity(); |
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} else { |
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if ($this->shouldDecreaseCapacity()) { |
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$this->decreaseCapacity(); |
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} |
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} |
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} |
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/** |
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* Called when capacity should be increased to accommodate new values. |
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*/ |
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protected function increaseCapacity() |
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{ |
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$this->allocate(max($this->count(), $this->capacity * $this->getGrowthFactor())); |
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} |
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/** |
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* Called when capacity should be decrease if it drops below a threshold. |
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*/ |
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protected function decreaseCapacity() |
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{ |
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$this->allocate(max(self::MIN_CAPACITY, $this->capacity * $this->getDecayFactor())); |
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} |
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/** |
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* @return bool whether capacity should be increased. |
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*/ |
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protected function shouldDecreaseCapacity(): bool |
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{ |
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return $this->count() <= $this->capacity * $this->getTruncateThreshold(); |
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} |
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/** |
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* @return bool whether capacity should be increased. |
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*/ |
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protected function shouldIncreaseCapacity(): bool |
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{ |
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return $this->count() >= $this->capacity; |
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} |
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/** |
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* Gets the size of the array. |
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* |
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* @return int |
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*/ |
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abstract protected function count(): int; |
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/** |
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* Change the size of an array to the new size of size. |
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* If size is less than the current array size, any values after the |
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* new size will be discarded. If size is greater than the current |
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* array size, the array will be padded with NULL values. |
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* |
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* @param int $size The new array size. This should be a value between 0 |
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* and PHP_INT_MAX. |
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* @return bool Returns TRUE on success or FALSE on failure. |
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*/ |
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abstract protected function setSize(int $size): bool; |
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} |
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MBHFramework /
structures
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