MBHFramework /
structures
| 1 | <?php namespace Mbh\Traits; |
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| 2 | |||
| 3 | /** |
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| 4 | * MBHFramework |
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| 5 | * |
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| 6 | * @link https://github.com/MBHFramework/mbh-framework |
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| 7 | * @copyright Copyright (c) 2017 Ulises Jeremias Cornejo Fandos |
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| 8 | * @license https://github.com/MBHFramework/mbh-framework/blob/master/LICENSE (MIT License) |
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| 9 | */ |
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| 10 | |||
| 11 | trait Capacity |
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| 12 | { |
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| 13 | /** |
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| 14 | * @var integer internal capacity |
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| 15 | */ |
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| 16 | protected $capacity = self::MIN_CAPACITY; |
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| 17 | |||
| 18 | /** |
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| 19 | * @inheritDoc |
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| 20 | */ |
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| 21 | public function capacity(): int |
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| 22 | { |
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| 23 | return $this->capacity; |
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| 24 | } |
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| 25 | |||
| 26 | /** |
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| 27 | * @inheritDoc |
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| 28 | */ |
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| 29 | public function allocate(int $capacity) |
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| 30 | { |
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| 31 | $this->capacity = max($capacity, $this->capacity); |
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| 32 | } |
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| 33 | |||
| 34 | /** |
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| 35 | * @return float The structures growth factor. |
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| 36 | */ |
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| 37 | protected function getGrowthFactor(): float |
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| 38 | { |
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| 39 | return 2; |
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| 40 | } |
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| 41 | |||
| 42 | /** |
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| 43 | * @return float to multiply by when decreasing capacity. |
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| 44 | */ |
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| 45 | protected function getDecayFactor(): float |
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| 46 | { |
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| 47 | return 0.5; |
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| 48 | } |
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| 49 | |||
| 50 | /** |
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| 51 | * @return float The ratio between size and capacity when capacity should be |
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| 52 | * decreased. |
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| 53 | */ |
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| 54 | protected function getTruncateThreshold(): float |
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| 55 | { |
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| 56 | return 0.25; |
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| 57 | } |
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| 58 | |||
| 59 | /** |
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| 60 | * Checks and adjusts capacity if required. |
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| 61 | */ |
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| 62 | protected function checkCapacity() |
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| 63 | { |
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| 64 | if ($this->shouldIncreaseCapacity()) { |
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| 65 | $this->increaseCapacity(); |
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| 66 | } else { |
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| 67 | if ($this->shouldDecreaseCapacity()) { |
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| 68 | $this->decreaseCapacity(); |
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| 69 | } |
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| 70 | } |
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| 71 | } |
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| 72 | |||
| 73 | /** |
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| 74 | * Called when capacity should be increased to accommodate new values. |
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| 75 | */ |
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| 76 | protected function increaseCapacity() |
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| 77 | { |
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| 78 | $this->capacity = max($this->count(), $this->capacity * $this->getGrowthFactor()); |
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| 79 | } |
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| 80 | |||
| 81 | /** |
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| 82 | * Called when capacity should be decrease if it drops below a threshold. |
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| 83 | */ |
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| 84 | protected function decreaseCapacity() |
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| 85 | { |
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| 86 | $this->capacity = max(self::MIN_CAPACITY, $this->capacity * $this->getDecayFactor()); |
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| 87 | } |
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| 88 | |||
| 89 | /** |
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| 90 | * @return bool whether capacity should be increased. |
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| 91 | */ |
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| 92 | protected function shouldDecreaseCapacity(): bool |
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| 93 | { |
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| 94 | return $this->count() <= $this->capacity * $this->getTruncateThreshold(); |
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| 95 | } |
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| 96 | |||
| 97 | /** |
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| 98 | * @return bool whether capacity should be increased. |
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| 99 | */ |
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| 100 | protected function shouldIncreaseCapacity(): bool |
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| 101 | { |
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| 102 | return $this->count() >= $this->capacity; |
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| 103 | } |
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| 104 | |||
| 105 | /** |
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| 106 | * Gets the size of the array. |
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| 107 | * |
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| 108 | * @return int |
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| 109 | */ |
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| 110 | abstract protected function count(): int; |
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| 111 | } |
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| 112 |