php-SPL庫迭代器類

SPL提供了多個迭代器類，分別提供了迭代訪問、過濾資料、緩衝結果、控制分頁等功能。，因為php總是在不斷壯大，我儘可能列出SPL中所有的迭代類。下面其中一些迭代器類是需要php5.4，另外一些如SearhIteratoer類在最新的php版本中已經去除1.ArrayIteratoer從PHP數組建立一個迭代器，當其和IteratorAggregate類一起使用時，免去了直接實現Iterator介面的方法的工作。<樣本>     $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返回給定數量的結果以及從集合中取出結果的起始索引點：<樣本>     // 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  按順序迭代訪問幾個不同的迭代器。例如，希望在一次迴圈中迭代訪問兩個或者更多的組合。這個迭代器的append方法類似於array_merge()函數來合并數組。     $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$current."\n";     }     /**output    a    b    c    d    e    f     */ 4. FilterIterator基於OuterIterator介面，用於過濾資料，返回合格元素。必須實現一個抽象方法accept()，此方法必須為迭代器的當前項返回true或false     class UserFilter extends FilterIterator     {         private$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);     //去除掉名為abdul的人員     $iterator = new UserFilter($object->getIterator(), 'abdul');     foreach ($iteratoras$result) {         echo$result['name'];     }          /**output    Jonathan    **/ 5. RegexIterator繼承FilterIterator，支援使用Regex模式比對和修改迭代器中的元素。經常用於將字串匹配。     $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一種通用類型的迭代器，所有實現了Traversable介面的類都可以被它迭代訪問。7. CachingIterator用來執行提前讀取一個元素的迭代操作，例如可以用於確定當前元素是否為最後一個元素。     $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用於建立非順序訪問的迭代器，允許跳轉到迭代器中的任何一點上。     $array = array("apple", "banana", "cherry", "damson", "elderberry");     $iterator = new ArrayIterator($array);     $iterator->seek(3);     echo$iterator->current();     /**output    damson     **/ 9. NoRewindIterator用於不能多次迭代的集合，適用於在迭代過程中執行一次性操作。     $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一種預留位置形式的迭代器，不執行任何操作。當要實現某個抽象類別的方法並且這個方法需要返回一個迭代器時，可以使用這種迭代器。11. InfiniteIterator用於持續地訪問資料，當迭代到最後一個元素時，會再次從第一個元素開始迭代訪問。     $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建立一個用於遞迴形式數組結構的迭代器，類似於多維陣列.它為許多更複雜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 ($iterator->valid()) {         //檢查是否含有子節點         if ($iterator->hasChildren()) {             //輸出所以位元組點             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將一個樹形結構的迭代器展開為一維結構。     $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以可視在方式顯示一個樹形結構。     $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是一個擴充的FilterIterator迭代器，它可以過濾掉來自於RecursiveIterator迭代器的非父元素，只找出子節點的索引值。通俗來說，就是去枝留葉。     $hey = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));     $arrayIterator = new RecursiveArrayIterator($hey);     $it = new ParentIterator($arrayIterator);     print_r(iterator_to_array($it));     /**output    Array        (        [0] => Array        (            [a] => apple            [p] => pear        )    )     **/ 16. RecursiveFilterIterator是FilterIterator迭代器的遞迴形式，也要求實現抽象的accept()方法，但在這個方法中應該使用$this->getInnerIterator()方法訪問當前正在迭代的迭代器。     class TestsOnlyFilter extends RecursiveFilterIterator     {         publicfunction accept()         {             // 找出含有“葉”的元素             return$this->hasChildren() || (mb_strpos($this->current(), "葉") !== FALSE);         }     }          $array = array("葉1", array("李2", "葉3", "葉4"), "葉5");     $iterator = new RecursiveArrayIterator($array);     $filter = new TestsOnlyFilter($iterator);     $filter = new RecursiveIteratorIterator($filter);     print_r(iterator_to_array($filter));     /**output    Array    (        [0] => 葉1        [1] => 葉3        [2] => 葉5    )    **/ 17. RecursiveRegexIterator是RegexIterator迭代器的遞迴形式，只接受RecursiveIterator迭代器作為迭代對象。     $rArrayIterator = new RecursiveArrayIterator(array('葉1', array('tet3', '葉4', '葉5')));     $rRegexIterator = new RecursiveRegexIterator($rArrayIterator, '/^葉/',         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: 葉4 葉5      **/ 18. RecursiveCachingIterator在RecursiveIterator迭代器上執行提前讀取一個元素的遞迴操作。 19. CallbackFilterIterator(PHP5.4)同時執行過濾和回調操作，在找到一個匹配的元素之後會調用回呼函數。     $hey = array( "李1", "葉2", "葉3", "葉4", "葉5", "葉6",);     $arrayIterator = new RecursiveArrayIterator($hey);     function isYe($current)     {         return mb_strpos($current,'葉') !== false;     }          $rs = new CallbackFilterIterator($arrayIterator, 'isYe');     print_r(iterator_to_array($rs));          /**output    Array    (        [0] => 葉2        [1] => 葉3        [2] => 葉4        [3] => 葉5        [4] => 葉6    )     **/ 20. DirectoryIterator目錄檔案遍曆器 方    法描    述DirectoryIterator::getSize得到檔案大小DirectoryIterator::getType得到檔案類型DirectoryIterator::isDir如果當前項是一個目錄，返回trueDirectoryIterator::isDot如果當前項是.或..，返回trueDirectoryIterator::isExecutable如果檔案可執行，返回trueDirectoryIterator::isFile如果檔案是一個常規檔案，返回trueDirectoryIterator::isLink如果檔案是一個符號連結，返回trueDirectoryIterator::isReadable如果檔案可讀，返回trueDirectoryIterator::isWritable如果檔案可寫，返回trueDirectoryIterator::key返回目前的目錄項DirectoryIterator::next移動到下一項DirectoryIterator::rewind將目錄指標返回到開始位置DirectoryIterator::valid檢查目錄中是否包含更多項    $it = new DirectoryIterator("../");     foreach ($itas$file) {         //用isDot ()方法分別過濾掉“.”和“..”目錄         if (!$it->isDot()) {             echo$file . "\n";         }     } 21. RecursiveDirectoryIterator遞迴目錄檔案遍曆器，可實現列出所有目錄階層，而不是只操作一個目錄。 方    法描    述RecursiveDirectoryIterator::getChildren如果這是一個目錄，為當前項返回一個迭代器RecursiveDirectoryIterator::hasChildren返回當前項是否是一個目錄而不是.或..RecursiveDirectoryIterator::key返回目前的目錄項的路徑和檔案名稱RecursiveDirectoryIterator::next移動到下一項RecursiveDirectoryIterator::rewind將目錄指標返回到開始位置RecursiveIteratorIterator::current訪問當前元素值RecursiveIteratorIterator::getDepth得到遞迴迭代的當前深度RecursiveIteratorIterator::getSubIterator得到當前活動子迭代器RecursiveIteratorIterator::key訪問當前鍵RecursiveIteratorIterator::next前移到下一個元素RecursiveIteratorIterator::rewind將迭代器返回到頂級內層迭代器的第一個元素RecursiveIteratorIterator::valid檢查當前位置是否合法    //列出指定目錄中所有檔案     $path = realpath('../');     $objects = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path), RecursiveIteratorIterator::SELF_FIRST);     foreach ($objectsas$name => $object) {         echo"$name\n";     } 22. FilesystemIterator是DirectoryIterator的遍曆器     $it = new FilesystemIterator('../');     foreach ($itas$fileinfo) {         echo$fileinfo->getFilename() . "\n";     } 23. GlobIterator帶匹配模式的檔案遍曆器    //找出../目錄中.php副檔名的檔案     $iterator = new GlobIterator('./*.php');     if (!$iterator->count()) {         echo'無php檔案';     } else {         $n = 0;         printf("總計 %d 個php檔案\r\n", $iterator->count());         foreach ($iteratoras$item) {             printf("[%d] %s\r\n", ++$n, $iterator->key());         }     }     /**output     總計 23 個php檔案     [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用於迭代器的連接器，具體看樣本     $person_id = new ArrayIterator(array('001', '002', '003'));     $person_name = new ArrayIterator(array('張三', '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"串連的迭代器個數:".$mit->countIterators() . "\n"; //3     foreach ($mitas$person) {         print_r($person);     }     /**output    Array    (        [ID] => 001        [NAME] => 張三        [AGE] => 22    )    Array    (        [ID] => 002        [NAME] => 李四        [AGE] => 23    )    Array    (        [ID] => 003        [NAME] => 王五        [AGE] => 11    )     **/ 25. RecursiveCallbackFilterIterator(PHP5.4)在RecursiveIterator迭代器上進行遞迴操作，同時執行過濾和回調操作，在找到一個匹配的元素之後會調用回呼函數。     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文檔訪問迭代器，可實現訪問xml中所有節點     $xml = <<                      PHP Basics             Jim Smith                  XML basics          XML;     // SimpleXML轉換為數組     function sxiToArray($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            )    )     **/ 

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