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    ▪PHP迭代器的内部执行过程详解       代码如下:class myIterator implements Iterator {    private $position = 0;    private $array = array(        "first_element",        "second_element",        "last_element",    );      public function __constru.........

    ▪PHP迭代器实现斐波纳契数列的函数       代码如下:class Fibonacci implements Iterator {     private $previous = 1;     private $current = 0;     private $key = 0;     public function current() {         return $this->current;     }     public function key() .........

    ▪PHP SPL使用方法和他的威力       SPL，PHP 标准库（Standard PHP Library） ，此从 PHP 5.0 起内置的组件和接口，并且从 PHP5.3 已逐渐的成熟。SPL 其实在所有的 PHP5 开发环境中被内置，同时无需任何设置。似乎众多的 PHP 开发人员基.........

代码如下:

class myIterator implements Iterator {
    private $position = 0;
    private $array = array(
        "first_element",
        "second_element",
        "last_element",
    ); 

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

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

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

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

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

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

$it = new myIterator;

foreach($it as $key => $value) {
 echo '输出键值：';
    var_dump($key, $value);
 //echo $key;
    echo "\n";
}

代码如下:

string(18) "myIterator::rewind"
string(17) "myIterator::valid"
string(19) "myIterator::current"
string(15) "myIterator::key"
输出键值：int(0)
string(13) "first_element"

string(16) "myIterator::next"
string(17) "myIterator::valid"
string(19) "myIterator::current"
string(15) "myIterator::key"
输出键值：int(1)
string(14) "second_element"

string(16) "myIterator::next"
string(17) "myIterator::valid"
string(19) "myIterator::current"
string(15) "myIterator::key"
输出键值：int(2)
string(12) "last_element"

string(16) "myIterator::next"
string(17) "myIterator::valid"

代码如下:

/**
* @author 简明现代魔法 http://www.nowamagic.net
*/
class MyIterator implements Iterator
{
     private $var = array();

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

     public function rewind() {
         echo "倒回第一个元素\n";
        reset($this->var);
     }

     public function current() {
        $var = current($this->var);
         echo "当前元素: $var\n";
         return $var;
     }

     public function key() {
        $var = key($this->var);
         echo "当前元素的键: $var\n";
         return $var;
     }

     public function next() {
        $var = next($this->var);
         echo "移向下一个元素: $var\n";
         return $var;
     }

     public function valid() {
        $var = $this->current() !== false;
         echo "检查有效性: {$var}\n";
         return $var;
     }
}

$values = array(1,2,3);
$it = new MyIterator($values);

foreach ($it as $k => $v) {
     print "此时键值对 -- key $k: value $v\n\n";
}

代码如下:

倒回第一个元素
当前元素: 1
检查有效性: 1
当前元素: 1
当前元素的键: 0
此时键值对 -- key 0: value 1

移向下一个元素: 2
当前元素: 2
检查有效性: 1
当前元素: 2
当前元素的键: 1
此时键值对 -- key 1: value 2

移向下一个元素: 3
当前元素: 3
检查有效性: 1
当前元素: 3
当前元素的键: 2
此时键值对 -- key 2: value 3

移向下一个元素:
当前元素:
检查有效性:

代码如下:

class Fibonacci implements Iterator {
    private $previous = 1;
    private $current = 0;
    private $key = 0;

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

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

    public function next() {
  // 关键在这里
  // 将当前值保存到  $newprevious
        $newprevious = $this->current;
  // 将上一个值与当前值的和赋给当前值
        $this->current += $this->previous;
  // 前一个当前值赋给上一个值
        $this->previous = $newprevious;
        $this->key++;
    }

    public function rewind() {
        $this->previous = 1;
        $this->current = 0;
        $this->key = 0;
    }

    public function valid() {
        return true;
    }
}

$seq = new Fibonacci;
$i = 0;
foreach ($seq as $f) {
    echo "$f ";
    if ($i++ === 15) break;
}

代码如下:

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610

代码如下:

<?php
class MyLoader {
    public static function doAutoload($class) {
        // 本模块对应的 autoload 操作
    }
}

spl_autoload_register( array('MyLoader', 'doAutoload') );
?>

代码如下:

<?php
class RecursiveFileFilterIterator extends FilterIterator {
    // 满足条件的扩展名
    protected $ext = array('jpg','gif');
    /**
     * 提供 $path 并生成对应的目录迭代器
     */
    public function __construct($path) {
        parent::__construct(new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path)));
    }
    /**
     * 检查文件扩展名是否满足条件
     */
    public function accept() {
        $item = $this->getInnerIterator();
        if ($item->isFile() &&
                in_array(pathinfo($item->getFilename(), PATHINFO_EXTENSION), $this->ext)) {
            return TRUE;
        }
    }
}
// 实例化
foreach (new RecursiveFileFilterIterator('/path/to/something') as $item) {
    echo $item . PHP_EOL;
}
?>