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<?php declare(strict_types=1); |
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namespace Dryist; |
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use InvalidArgumentException; |
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/** |
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* Count the number of items. |
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* |
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* @see https://php.net/iterator_count |
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*/ |
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function count(iterable $items): int |
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{ |
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$total = 0; |
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foreach ($items as $_) { |
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$total++; |
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} |
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return $total; |
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} |
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/** |
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* Combine a list of keys and a list of values into a map. |
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*/ |
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function combine(iterable $keys, iterable $values): iterable |
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{ |
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if (count($keys) !== count($values)) { |
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throw new InvalidArgumentException("Count of keys and values do not match"); |
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} |
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foreach ($keys as $key) { |
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yield $key => \current($values); |
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\next($values); |
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} |
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} |
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/** |
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* Limit items by a predicate applied to value. |
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* |
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* Example predicate: |
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* |
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* function ($value): bool { |
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* return $value > 1; |
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* } |
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*/ |
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function filter(iterable $items, callable $accept): iterable |
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{ |
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foreach ($items as $key => $item) { |
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if ($accept($item)) { |
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yield $key => $item; |
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} |
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} |
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} |
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/** |
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* Limit items by a predicate applied to key. |
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* |
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* Example predicate: |
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* |
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* function ($key): bool { |
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* return $key % 2 === 0; |
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* } |
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*/ |
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function filterKey(iterable $items, callable $accept): iterable |
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{ |
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foreach ($items as $key => $item) { |
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if ($accept($key)) { |
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yield $key => $item; |
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} |
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} |
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} |
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/** |
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* Resolve a list of keys from a map. |
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*/ |
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function keys(iterable $items): iterable |
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{ |
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foreach ($items as $key => $value) { |
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yield $key; |
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} |
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} |
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/** |
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* Apply a modifier to every item. |
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* |
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* Example modifier: |
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* |
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* function ($value) { |
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* return $value; |
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* } |
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*/ |
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function map(iterable $items, callable $modify): iterable |
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{ |
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foreach ($items as $key => $value) { |
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yield $key => $modify($value); |
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} |
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} |
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/** |
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* Apply a modifier to every item with the key. |
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* |
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* Example modifier: |
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* |
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* function ($key, $value) { |
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* return $value; |
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* } |
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*/ |
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function mapBoth(iterable $items, callable $modify): iterable |
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{ |
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foreach ($items as $key => $value) { |
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yield $key => $modify($key, $value); |
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} |
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} |
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/** |
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* Apply a modifier to every item key. |
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* |
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* Example modifier: |
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* |
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* function ($key) { |
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* return $key; |
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* } |
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*/ |
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function mapKey(iterable $items, callable $modify): iterable |
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{ |
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foreach ($items as $key => $value) { |
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yield $modify($key) => $value; |
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} |
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} |
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/** |
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* Resolve an iterable to an array. |
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* |
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* @link https://php.net/iterator_to_array |
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*/ |
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function resolve(iterable $items): array |
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{ |
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if (is_array($items)) { |
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return $items; |
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} |
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return \iterator_to_array($items); |
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} |
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/** |
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* Limit items in a map by a list of keys. |
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*/ |
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function take(iterable $items, array $keys): iterable |
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{ |
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return filterKey($items, function ($key) use ($keys): bool { |
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return \in_array($key, $keys, true); |
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}); |
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} |
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/** |
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* Resolve a map into a list. |
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*/ |
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function values(iterable $items): iterable |
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{ |
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foreach ($items as $value) { |
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yield $value; |
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} |
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} |
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