SeekableIterator 接口

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

简介

Seekable 迭代器。

接口摘要

interface SeekableIterator extends Iterator {
/* 方法 */
public seek(int $offset): void
/* 继承的方法 */
public Iterator::current(): mixed
public Iterator::key(): mixed
public Iterator::next(): void
public Iterator::rewind(): void
public Iterator::valid(): bool
}

示例

示例 #1 基础用法

本示例演示了如何创建自定义 SeekableIterator、查找位置和处理无效位置。

<?php
class MySeekableIterator implements SeekableIterator {

private $position;

private $array = array(
"first element",
"second element",
"third element",
"fourth element"
);

/* SeekableIterator 接口所需的方法 */

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

$this->position = $position;
}

/* Iterator 接口所需的方法 */

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]);
}
}

try {

$it = new MySeekableIterator;
echo $it->current(), "\n";

$it->seek(2);
echo $it->current(), "\n";

$it->seek(1);
echo $it->current(), "\n";

$it->seek(10);

} catch (OutOfBoundsException $e) {
echo $e->getMessage();
}
?>

以上示例的输出类似于：

first element
third element
second element
invalid seek position (10)

目录