$v) {
if ($k === $key) {
return \true;
}
}
return \false;
}
/**
* Returns the first item (matching the specified predicate if given). If there is no such item, it returns result of invoking $else or null.
* @template K
* @template V
* @param iterable $iterable
* @param ?callable(V, K, iterable): bool $predicate
* @return ?V
*/
public static function first(iterable $iterable, ?callable $predicate = null, ?callable $else = null)
{
foreach ($iterable as $k => $v) {
if (!$predicate || $predicate($v, $k, $iterable)) {
return $v;
}
}
return $else ? $else() : null;
}
/**
* Returns the key of first item (matching the specified predicate if given). If there is no such item, it returns result of invoking $else or null.
* @template K
* @template V
* @param iterable $iterable
* @param ?callable(V, K, iterable): bool $predicate
* @return ?K
*/
public static function firstKey(iterable $iterable, ?callable $predicate = null, ?callable $else = null)
{
foreach ($iterable as $k => $v) {
if (!$predicate || $predicate($v, $k, $iterable)) {
return $k;
}
}
return $else ? $else() : null;
}
/**
* Tests whether at least one element in the iterator passes the test implemented by the provided function.
* @template K
* @template V
* @param iterable $iterable
* @param callable(V, K, iterable): bool $predicate
*/
public static function some(iterable $iterable, callable $predicate) : bool
{
foreach ($iterable as $k => $v) {
if ($predicate($v, $k, $iterable)) {
return \true;
}
}
return \false;
}
/**
* Tests whether all elements in the iterator pass the test implemented by the provided function.
* @template K
* @template V
* @param iterable $iterable
* @param callable(V, K, iterable): bool $predicate
*/
public static function every(iterable $iterable, callable $predicate) : bool
{
foreach ($iterable as $k => $v) {
if (!$predicate($v, $k, $iterable)) {
return \false;
}
}
return \true;
}
/**
* Iterator that filters elements according to a given $predicate. Maintains original keys.
* @template K
* @template V
* @param iterable $iterable
* @param callable(V, K, iterable): bool $predicate
* @return \Generator
*/
public static function filter(iterable $iterable, callable $predicate) : \Generator
{
foreach ($iterable as $k => $v) {
if ($predicate($v, $k, $iterable)) {
(yield $k => $v);
}
}
}
/**
* Iterator that transforms values by calling $transformer. Maintains original keys.
* @template K
* @template V
* @template R
* @param iterable $iterable
* @param callable(V, K, iterable): R $transformer
* @return \Generator
*/
public static function map(iterable $iterable, callable $transformer) : \Generator
{
foreach ($iterable as $k => $v) {
(yield $k => $transformer($v, $k, $iterable));
}
}
/**
* Iterator that transforms keys and values by calling $transformer. If it returns null, the element is skipped.
* @template K
* @template V
* @template ResV
* @template ResK
* @param iterable $iterable
* @param callable(V, K, iterable): ?array{ResV, ResK} $transformer
* @return \Generator
*/
public static function mapWithKeys(iterable $iterable, callable $transformer) : \Generator
{
foreach ($iterable as $k => $v) {
$pair = $transformer($v, $k, $iterable);
if ($pair) {
(yield $pair[0] => $pair[1]);
}
}
}
/**
* Wraps around iterator and caches its keys and values during iteration.
* This allows the data to be re-iterated multiple times.
* @template K
* @template V
* @param iterable $iterable
* @return \IteratorAggregate
*/
public static function memoize(iterable $iterable) : iterable
{
return new class(self::toIterator($iterable)) implements \IteratorAggregate
{
/**
* @var \Iterator
*/
private $iterator;
/**
* @var mixed[]
*/
private $cache = [];
public function __construct(\Iterator $iterator, array $cache = [])
{
$this->iterator = $iterator;
$this->cache = $cache;
}
public function getIterator() : \Generator
{
if (!$this->cache) {
$this->iterator->rewind();
}
$i = 0;
while (\true) {
if (isset($this->cache[$i])) {
[$k, $v] = $this->cache[$i];
} elseif ($this->iterator->valid()) {
$k = $this->iterator->key();
$v = $this->iterator->current();
$this->iterator->next();
$this->cache[$i] = [$k, $v];
} else {
break;
}
(yield $k => $v);
$i++;
}
}
};
}
/**
* Creates an iterator from anything that is iterable.
* @template K
* @template V
* @param iterable $iterable
* @return \Iterator
*/
public static function toIterator(iterable $iterable) : \Iterator
{
switch (\true) {
case $iterable instanceof \Iterator:
return $iterable;
case $iterable instanceof \IteratorAggregate:
return self::toIterator($iterable->getIterator());
case \is_array($iterable):
return new \ArrayIterator($iterable);
}
}
}