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 */
}

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)

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