php-SPL库迭代器类

SPL提供了多个迭代器类，分别提供了迭代访问、过滤数据、缓存结果、控制分页等功能。，因为php总是在不断壮大，我尽可能列出SPL中所有的迭代类。下面其中一些迭代器类是需要php5.4，另外一些如SearhIteratoer类在最新的php版本中已经去除1.ArrayIteratoer从PHP数组创建一个迭代器，当其和IteratorAggregate类一起使用时，免去了直接实现Iterator接口的方法的工作。<示例>     $b = array(         'name'=> 'mengzhi',         'age' => '12',         'city'=> 'shanghai'     );     $a = new ArrayIterator($b);     $a->append(array(                     'home' => 'china',                     'work' => 'developer'                ));     $c = $a->getArrayCopy();     print_r($a);     print_r($c);          /**output    ArrayIterator Object    (        [storage:ArrayIterator:private] => Array        (        [name] => mengzhi                [age] => 12                [city] => shanghai                [0] => Array        (        [home] => china                        [work] => developer                    )            )    )    Array        (        [name] => mengzhi        [age] => 12        [city] => shanghai        [0] => Array        (        [home] => china                [work] => developer            )    )    **/ 2. LimitIterator返回给定数量的结果以及从集合中取出结果的起始索引点：<示例>     // Create an iterator to be limited     $fruits = new ArrayIterator(array(                                      'apple',                                      'banana',                                      'cherry',                                      'damson',                                      'elderberry'                                 ));     // Loop over first three fruits only     foreach (new LimitIterator($fruits, 0, 3) as$fruit) {         var_dump($fruit);     }     echo"\n";     // Loop from third fruit until the end     // Note: offset starts from zero for apple     foreach (new LimitIterator($fruits, 2) as$fruit) {         print_r($fruit);     }          /**output    string(5) "apple"    string(6) "banana"    string(6) "cherry"    cherrydamsonelderberry     */ 3. AppendIterator  按顺序迭代访问几个不同的迭代器。例如，希望在一次循环中迭代访问两个或者更多的组合。这个迭代器的append方法类似于array_merge()函数来合并数组。     $array_a = new ArrayIterator(array('a', 'b', 'c'));     $array_b = new ArrayIterator(array('d', 'e', 'f'));     $iterator = new AppendIterator;     $iterator->append($array_a);     $iterator->append($array_b);     foreach ($iteratoras$current) {         echo$current."\n";     }     /**output    a    b    c    d    e    f     */ 4. FilterIterator基于OuterIterator接口，用于过滤数据，返回符合条件的元素。必须实现一个抽象方法accept()，此方法必须为迭代器的当前项返回true或false     class UserFilter extends FilterIterator     {         private$userFilter;              publicfunction __construct(Iterator $iterator, $filter)         {             parent::__construct($iterator);             $this->userFilter = $filter;         }              publicfunction accept()         {             $user = $this->getInnerIterator()->current();             if (strcasecmp($user['name'], $this->userFilter) == 0) {                 return false;             }             return true;         }     }          $array = array(         array(             'name' => 'Jonathan',             'id'   => '5'         ),         array(             'name' => 'Abdul',             'id'   => '22'         )     );     $object = new ArrayObject($array);     //去除掉名为abdul的人员     $iterator = new UserFilter($object->getIterator(), 'abdul');     foreach ($iteratoras$result) {         echo$result['name'];     }          /**output    Jonathan    **/ 5. RegexIterator继承FilterIterator，支持使用正则表达式模式匹配和修改迭代器中的元素。经常用于将字符串匹配。     $a = new ArrayIterator(array('test1', 'test2', 'test3'));     $i = new RegexIterator($a, '/^(test)(\d+)/', RegexIterator::REPLACE);     $i->replacement = '$2:$1';     print_r(iterator_to_array($i));          /**output    Array    (        [0] => 1:test        [1] => 2:test        [2] => 3:test    )     **/ 6. IteratorIterator一种通用类型的迭代器，所有实现了Traversable接口的类都可以被它迭代访问。7. CachingIterator用来执行提前读取一个元素的迭代操作，例如可以用于确定当前元素是否为最后一个元素。     $array = array('koala', 'kangaroo', 'wombat', 'wallaby', 'emu', 'kiwi', 'kookaburra', 'platypus');     try {         $object = new CachingIterator(new ArrayIterator($array));         foreach ($objectas$value) {             echo$value;             if ($object->hasNext()) {                 echo',';             }         }     }     catch (Exception $e) {         echo$e->getMessage();     }     /**output    koala,kangaroo,wombat,wallaby,emu,kiwi,kookaburra,platypus     **/ 8. SeekableIterator用于创建非顺序访问的迭代器，允许跳转到迭代器中的任何一点上。     $array = array("apple", "banana", "cherry", "damson", "elderberry");     $iterator = new ArrayIterator($array);     $iterator->seek(3);     echo$iterator->current();     /**output    damson     **/ 9. NoRewindIterator用于不能多次迭代的集合，适用于在迭代过程中执行一次性操作。     $fruit = array('apple', 'banana', 'cranberry');     $arr = new ArrayObject($fruit);     $it = new NoRewindIterator($arr->getIterator());     echo"Fruit A:\n";     foreach ($itas$item) {         echo$item . "\n";     }          echo"Fruit B:\n";     foreach ($itas$item) {         echo$item . "\n";     }     /**output    Fruit A:    apple    banana    cranberry    Fruit B:     **/ 10. EmptyIterator一种占位符形式的迭代器，不执行任何操作。当要实现某个抽象类的方法并且这个方法需要返回一个迭代器时，可以使用这种迭代器。11. InfiniteIterator用于持续地访问数据，当迭代到最后一个元素时，会再次从第一个元素开始迭代访问。     $arrayit = new ArrayIterator(array('cat', 'dog'));     $infinite = new InfiniteIterator($arrayit);     $limit = new LimitIterator($infinite, 0, 7);     foreach ($limitas$value) {         echo"$value\n";     }     /**output    cat    dog    cat    dog    cat    dog    cat     **/ 12. RecursiveArrayIterator创建一个用于递归形式数组结构的迭代器，类似于多维数组.它为许多更复杂的迭代器提供了所需的操作，如RecursiveTreeIterator和RecursiveIteratorIterator迭代器。    $fruits = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));     $iterator = new RecursiveArrayIterator($fruits);     while ($iterator->valid()) {         //检查是否含有子节点         if ($iterator->hasChildren()) {             //输出所以字节点             foreach ($iterator->getChildren() as$key => $value) {                 echo$key . ' : ' . $value . "\n";             }         } else {             echo"No children.\n";         }         $iterator->next();     }          /**output    No children.    No children.    a : apple    p : pear     **/ 13. RecursiveIteratorIterator将一个树形结构的迭代器展开为一维结构。     $fruits = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));     $arrayiter = new RecursiveArrayIterator($fruits);     $iteriter = new RecursiveIteratorIterator($arrayiter);     foreach ($iteriteras$key => $value) {         $d = $iteriter->getDepth();         echo"depth=$d k=$key v=$value\n";     }          /**output    depth=0 k=a v=lemon    depth=0 k=b v=orange    depth=1 k=a v=apple    depth=1 k=p v=pear     **/ 14. RecursiveTreeIterator以可视在方式显示一个树形结构。     $hey = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));     $awesome = new RecursiveTreeIterator(         new RecursiveArrayIterator($hey),         null, null, RecursiveIteratorIterator::LEAVES_ONLY     );     foreach ($awesomeas$line)         echo$line . PHP_EOL;          /**output    |-lemon    |-orange        |-apple        \-pear     **/  15. ParentIterator是一个扩展的FilterIterator迭代器，它可以过滤掉来自于RecursiveIterator迭代器的非父元素，只找出子节点的键值。通俗来说，就是去枝留叶。     $hey = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));     $arrayIterator = new RecursiveArrayIterator($hey);     $it = new ParentIterator($arrayIterator);     print_r(iterator_to_array($it));     /**output    Array        (        [0] => Array        (            [a] => apple            [p] => pear        )    )     **/ 16. RecursiveFilterIterator是FilterIterator迭代器的递归形式，也要求实现抽象的accept()方法，但在这个方法中应该使用$this->getInnerIterator()方法访问当前正在迭代的迭代器。     class TestsOnlyFilter extends RecursiveFilterIterator     {         publicfunction accept()         {             // 找出含有“叶”的元素             return$this->hasChildren() || (mb_strpos($this->current(), "叶") !== FALSE);         }     }          $array = array("叶1", array("李2", "叶3", "叶4"), "叶5");     $iterator = new RecursiveArrayIterator($array);     $filter = new TestsOnlyFilter($iterator);     $filter = new RecursiveIteratorIterator($filter);     print_r(iterator_to_array($filter));     /**output    Array    (        [0] => 叶1        [1] => 叶3        [2] => 叶5    )    **/ 17. RecursiveRegexIterator是RegexIterator迭代器的递归形式，只接受RecursiveIterator迭代器作为迭代对象。     $rArrayIterator = new RecursiveArrayIterator(array('叶1', array('tet3', '叶4', '叶5')));     $rRegexIterator = new RecursiveRegexIterator($rArrayIterator, '/^叶/',         RecursiveRegexIterator::ALL_MATCHES);          foreach ($rRegexIteratoras$key1 => $value1) {         if ($rRegexIterator->hasChildren()) {             // print all children             echo"Children: ";             foreach ($rRegexIterator->getChildren() as$key => $value) {                 echo$value . " ";             }             echo"\n";         } else {             echo"No children\n";         }     }     /**output    No children    Children: 叶4 叶5      **/ 18. RecursiveCachingIterator在RecursiveIterator迭代器上执行提前读取一个元素的递归操作。 19. CallbackFilterIterator(PHP5.4)同时执行过滤和回调操作，在找到一个匹配的元素之后会调用回调函数。     $hey = array( "李1", "叶2", "叶3", "叶4", "叶5", "叶6",);     $arrayIterator = new RecursiveArrayIterator($hey);     function isYe($current)     {         return mb_strpos($current,'叶') !== false;     }          $rs = new CallbackFilterIterator($arrayIterator, 'isYe');     print_r(iterator_to_array($rs));          /**output    Array    (        [0] => 叶2        [1] => 叶3        [2] => 叶4        [3] => 叶5        [4] => 叶6    )     **/ 20. DirectoryIterator目录文件遍历器 方    法    描    述DirectoryIterator::getSize    得到文件大小DirectoryIterator::getType    得到文件类型DirectoryIterator::isDir  如果当前项是一个目录，返回trueDirectoryIterator::isDot   如果当前项是.或..，返回trueDirectoryIterator::isExecutable    如果文件可执行，返回trueDirectoryIterator::isFile 如果文件是一个常规文件，返回trueDirectoryIterator::isLink 如果文件是一个符号链接，返回trueDirectoryIterator::isReadable 如果文件可读，返回trueDirectoryIterator::isWritable  如果文件可写，返回trueDirectoryIterator::key 返回当前目录项DirectoryIterator::next  移动到下一项DirectoryIterator::rewind 将目录指针返回到开始位置DirectoryIterator::valid    检查目录中是否包含更多项    $it = new DirectoryIterator("../");     foreach ($itas$file) {         //用isDot ()方法分别过滤掉“.”和“..”目录         if (!$it->isDot()) {             echo$file . "\n";         }     } 21. RecursiveDirectoryIterator递归目录文件遍历器，可实现列出所有目录层次结构，而不是只操作一个目录。 方    法  描    述RecursiveDirectoryIterator::getChildren   如果这是一个目录，为当前项返回一个迭代器RecursiveDirectoryIterator::hasChildren 返回当前项是否是一个目录而不是.或..RecursiveDirectoryIterator::key  返回当前目录项的路径和文件名RecursiveDirectoryIterator::next  移动到下一项RecursiveDirectoryIterator::rewind    将目录指针返回到开始位置RecursiveIteratorIterator::current  访问当前元素值RecursiveIteratorIterator::getDepth  得到递归迭代的当前深度RecursiveIteratorIterator::getSubIterator    得到当前活动子迭代器RecursiveIteratorIterator::key    访问当前键RecursiveIteratorIterator::next    前移到下一个元素RecursiveIteratorIterator::rewind   将迭代器返回到顶级内层迭代器的第一个元素RecursiveIteratorIterator::valid    检查当前位置是否合法    //列出指定目录中所有文件     $path = realpath('../');     $objects = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path), RecursiveIteratorIterator::SELF_FIRST);     foreach ($objectsas$name => $object) {         echo"$name\n";     } 22. FilesystemIterator是DirectoryIterator的遍历器     $it = new FilesystemIterator('../');     foreach ($itas$fileinfo) {         echo$fileinfo->getFilename() . "\n";     } 23. GlobIterator带匹配模式的文件遍历器    //找出../目录中.php扩展名的文件     $iterator = new GlobIterator('./*.php');     if (!$iterator->count()) {         echo'无php文件';     } else {         $n = 0;         printf("总计 %d 个php文件\r\n", $iterator->count());         foreach ($iteratoras$item) {             printf("[%d] %s\r\n", ++$n, $iterator->key());         }     }     /**output     总计 23 个php文件     [1] .\1.php     [2] .\11.php     [3] .\12.php     [4] .\13.php     [5] .\14.php     [6] .\15.php     [7] .\16.php     [8] .\17.php     [9] .\19.php     [10] .\2.php     [11] .\20.php     [12] .\21.php     [13] .\22.php     [14] .\23.php     [15] .\24.php     [16] .\25.php     [17] .\26.php     [18] .\3.php     [19] .\4.php     [20] .\5.php     [21] .\7.php     [22] .\8.php     [23] .\9.php     **/ 24. MultipleIterator用于迭代器的连接器，具体看示例     $person_id = new ArrayIterator(array('001', '002', '003'));     $person_name = new ArrayIterator(array('张三', '李四', '王五'));     $person_age = new ArrayIterator(array(22, 23, 11));     $mit = new MultipleIterator(MultipleIterator::MIT_KEYS_ASSOC);     $mit->attachIterator($person_id, "ID");     $mit->attachIterator($person_name, "NAME");     $mit->attachIterator($person_age, "AGE");     echo"连接的迭代器个数:".$mit->countIterators() . "\n"; //3     foreach ($mitas$person) {         print_r($person);     }     /**output    Array    (        [ID] => 001        [NAME] => 张三        [AGE] => 22    )    Array    (        [ID] => 002        [NAME] => 李四        [AGE] => 23    )    Array    (        [ID] => 003        [NAME] => 王五        [AGE] => 11    )     **/ 25. RecursiveCallbackFilterIterator(PHP5.4)在RecursiveIterator迭代器上进行递归操作，同时执行过滤和回调操作，在找到一个匹配的元素之后会调用回调函数。     function doesntStartWithLetterT($current)     {         $rs = $current->getFileName();         return$rs[0] !== 'T';     }          $rdi = new RecursiveDirectoryIterator(__DIR__);     $files = new RecursiveCallbackFilterIterator($rdi, 'doesntStartWithLetterT');     foreach (new RecursiveIteratorIterator($files) as$file) {         echo$file->getPathname() . PHP_EOL;     }  26. SimpleXMLIteratorXMl文档访问迭代器，可实现访问xml中所有节点     $xml = <<<XML     <books>         <book>             <title>PHP Basics</title>             <author>Jim Smith</author>         </book>         <book>XML basics</book>     </books>     XML;     // SimpleXML转换为数组     function sxiToArray($sxi)     {         $a = array();         for ($sxi->rewind(); $sxi->valid(); $sxi->next()) {             if (!array_key_exists($sxi->key(), $a)) {                 $a[$sxi->key()] = array();             }             if ($sxi->hasChildren()) {                 $a[$sxi->key()][] = sxiToArray($sxi->current());             } else {                 $a[$sxi->key()][] = strval($sxi->current());             }         }         return$a;     }          $xmlIterator = new SimpleXMLIterator($xml);     $rs = sxiToArray($xmlIterator);     print_r($rs);     /**output    Array    (        [book] => Array            (                [0] => Array                    (                        [title] => Array                            (                                [0] => PHP Basics                            )                        [author] => Array                            (                                [0] => Jim Smith                            )                    )                [1] => XML basics            )    )     **/