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php iterator 实现

2026-01-29 15:33:02PHP

实现 PHP Iterator 接口

在 PHP 中，可以通过实现 Iterator 接口来创建自定义的可迭代对象。Iterator 接口定义了以下方法：

Iterator extends Traversable {
    public current(): mixed
    public key(): mixed
    public next(): void
    public rewind(): void
    public valid(): bool
}

基本实现示例

创建一个简单的迭代器类，遍历一个数组：

class MyIterator implements Iterator {
    private $array = [];
    private $position = 0;

    public function __construct(array $array) {
        $this->array = $array;
        $this->position = 0;
    }

    public function rewind() {
        $this->position = 0;
    }

    public function current() {
        return $this->array[$this->position];
    }

    public function key() {
        return $this->position;
    }

    public function next() {
        ++$this->position;
    }

    public function valid() {
        return isset($this->array[$this->position]);
    }
}

使用自定义迭代器

$data = ['apple', 'banana', 'cherry'];
$iterator = new MyIterator($data);

foreach ($iterator as $key => $value) {
    echo "Key: $key, Value: $value\n";
}

实现 Generator 的替代方案

PHP 5.5+ 提供了生成器（Generator）作为更简单的迭代器实现方式：

function myGenerator(array $array) {
    foreach ($array as $key => $value) {
        yield $key => $value;
    }
}

$data = ['apple', 'banana', 'cherry'];
foreach (myGenerator($data) as $key => $value) {
    echo "Key: $key, Value: $value\n";
}

实现 IteratorAggregate 接口

对于更复杂的场景，可以实现 IteratorAggregate 接口，它只需要实现一个 getIterator() 方法：

class MyCollection implements IteratorAggregate {
    private $items = [];

    public function addItem($item) {
        $this->items[] = $item;
    }

    public function getIterator() {
        return new ArrayIterator($this->items);
    }
}

$collection = new MyCollection();
$collection->addItem('apple');
$collection->addItem('banana');

foreach ($collection as $item) {
    echo $item . "\n";
}

实现 SeekableIterator 接口

如果需要随机访问功能，可以实现 SeekableIterator 接口：

php iterator 实现

class MySeekableIterator implements SeekableIterator {
    private $array = [];
    private $position = 0;

    public function __construct(array $array) {
        $this->array = $array;
    }

    public function seek($position) {
        if (!isset($this->array[$position])) {
            throw new OutOfBoundsException("Invalid position ($position)");
        }
        $this->position = $position;
    }

    // 实现其他 Iterator 方法...
}