Iterators in PHP

PHP iterators have been around since PHP 5, but are heavily under utilized. With all the built-in iterators there is no reason you shouldn't be leveraging it's power and flexibility. In this session you will learn about all the built-in PHP iterators and be guided on how to extend and/or create your own iterators.

Transcript

1. Iterators
   IN PHP
   NOW WITH GENERATORS
   

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2. http://bitly.com/wNwg6N
   

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3. An iterator is an object that enables a
   programmer to traverse a container. Various
   types of iterators are often provided via a
   container's interface.
   Source: http://en.wikipedia.org/wiki/Iterator
   

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4. PHP also have a lot of awesome features;
   at least two of them are in my opinion
   largely underused: Iterators and Streams.
   “
   ”
   Fabien Potencier (Lead Developer of Symfony Project)
   Source: http://fabien.potencier.org/article/44/php-iterators-and-streams-are-awesome
   

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5. One Iterator
   Two Iterator
   Three Iterator
   floor();
   

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6. Where are Iterators
   Used?
   

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7. Iterators in Source
   https://github.com/php/php-src/tree/master/ext/spl
   

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8. Everyone Loves
   Iterators
   

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9. Everyone Loves
   Iterators
   Have you used SimpleXML?
   

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10. Everyone Loves
    Iterators
    Have you used SimpleXML?
    Have you used pdo?
    

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11. class IterableFilterIterator extends FilterIterator {
    public function accept()
    {
    return in_array("Iterator", class_implements($this->current()));
    }
    }
    $classes = new IterableFilterIterator(new ArrayIterator(get_declared_classes()));
    foreach ($classes as $name) {
    echo $name . "\n";
    }
    Classes that implement Iterator
    

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12. class IterableFilterIterator extends FilterIterator {
    public function accept()
    {
    return in_array("Iterator", class_implements($this->current()));
    }
    }
    $classes = new IterableFilterIterator(new ArrayIterator(get_declared_classes()));
    foreach ($classes as $name) {
    echo $name . "\n";
    }
    Classes that implement Iterator
    Generator
    RecursiveIteratorIterator
    IteratorIterator
    FilterIterator
    RecursiveFilterIterator
    CallbackFilterIterator
    RecursiveCallbackFilterIterator
    ParentIterator
    LimitIterator
    CachingIterator
    RecursiveCachingIterator
    NoRewindIterator
    AppendIterator
    InfiniteIterator
    RegexIterator
    RecursiveRegexIterator
    EmptyIterator
    RecursiveTreeIterator
    ArrayIterator
    RecursiveArrayIterator
    DirectoryIterator
    FilesystemIterator
    RecursiveDirectoryIterator
    GlobIterator
    SplFileObject
    SplTempFileObject
    SplDoublyLinkedList
    SplQueue
    SplStack
    SplHeap
    SplMinHeap
    SplMaxHeap
    SplPriorityQueue
    SplFixedArray
    SplObjectStorage
    MultipleIterator
    IntlIterator
    IntlPartsIterator
    Phar
    PharData
    SimpleXMLIterator
    MongoCursor
    

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13. Defining an Iterator
    

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14. Iterator Interfaces
    

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15. Iterator Interfaces
    • Traversable
    • Iterator
    • RecursiveIterator
    • Countable
    • SeekableIterator
    Source: http://www.php.net/manual/en/spl.iterators.php
    

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16. Interface - Iterator
    Source: http://us.php.net/manual/en/class.iterator.php
    Iterator extends Traversable {
    /* Methods */
    abstract public mixed current ( void )
    abstract public scalar key ( void )
    abstract public void next ( void )
    abstract public void rewind ( void )
    abstract public boolean valid ( void )
    }
    

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17. Interface -
    RecursiveIterator
    Source: http://www.php.net/manual/en/spl.iterators.php
    RecursiveIterator extends Iterator {
    /* Methods */
    public RecursiveIterator getChildren ( void )
    public bool hasChildren ( void )
    /* Inherited methods */
    abstract public mixed Iterator::current ( void )
    abstract public scalar Iterator::key ( void )
    abstract public void Iterator::next ( void )
    abstract public void Iterator::rewind ( void )
    abstract public boolean Iterator::valid ( void )
    }
    

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18. Interface -
    Countable
    Source: http://www.php.net/manual/en/spl.iterators.php
    Countable {
    /* Methods */
    abstract public int count ( void )
    }
    

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19. Interface - Seekable
    Source: http://www.php.net/manual/en/spl.iterators.php
    SeekableIterator extends Iterator {
    /* Methods */
    abstract public void seek ( int $position )
    /* Inherited methods */
    abstract public mixed Iterator::current ( void )
    abstract public scalar Iterator::key ( void )
    abstract public void Iterator::next ( void )
    abstract public void Iterator::rewind ( void )
    abstract public boolean Iterator::valid ( void )
    }
    

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20. Iterator Basics
    

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21. Iterator Aggregate
    Iterator Aggregate is used when you
    need to offload iteration, and its
    methods, to another iterator
    public function getIterator() { ... }
    

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22. Iterator Aggregate
    Iterator Aggregate
    Iterator
    

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23. Outer Iterator
    Outer Iterators act as a wrapper layer.
    Outer iterator is iterated and then
    internally iterates over inner iterator.
    *
    *
    *
    ITERATOR!
    

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24. Outer Iterator
    Outer Iterator
    Inner
    Iterator
    

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25. Outer Iterator
    Outer Iterator
    Inner
    Iterator
    

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26. Recursive Iterator
    Recursive Iterators prepare an iterator
    to be recursively iterated.
    * Requires RecursiveIteratorIterator to
    properly recursively Iterate. *
    

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27. Recursive
    Iterator
    Recursive Iterator
    Get Children
    

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28. Iterator Notes
    If you use foreach it will auto rewind.
    Using for or while will require you to
    rewind iterator.
    

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29. Recursive Iterators
    

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30. $data = [
    'title' => 'how to work with iterators',
    'posts' => [
    [
    'title' => 'introduction to iterators',
    'email' => 'JohnDoe@example.com',
    ],
    [
    'title' => 'extending iterators',
    'email' => 'JaneDoe@example.com',
    ],
    ],
    ];
    foreach (new RecursiveArrayIterator($data) as $field => $val) {
    echo "{$field}:{$val}\n";
    }
    Sub Title
    Recursive*Iterator
    Recursively Iterate Array
    

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31. $data = [
    'title' => 'how to work with iterators',
    'posts' => [
    [
    'title' => 'introduction to iterators',
    'email' => 'JohnDoe@example.com',
    ],
    [
    'title' => 'extending iterators',
    'email' => 'JaneDoe@example.com',
    ],
    ],
    ];
    foreach (new RecursiveArrayIterator($data) as $field => $val) {
    echo "{$field}:{$val}\n";
    }
    Sub Title
    Recursive*Iterator
    Recursively Iterate Array
    title: how to work with iterators
    posts: Array
    

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32. $data = [
    'title' => 'how to work with iterators',
    'posts' => [
    [
    'title' => 'introduction to iterators',
    'email' => 'JohnDoe@example.com',
    ],
    [
    'title' => 'extending iterators',
    'email' => 'JaneDoe@example.com',
    ],
    ],
    ];
    foreach (new RecursiveArrayIterator($data) as $field => $val) {
    echo "{$field}:{$val}\n";
    }
    Sub Title
    Recursive*Iterator
    Recursively Iterate Array
    title: how to work with iterators
    posts: Array
    

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34. RecursiveIteratorIterator implements
    OuterIterator , Traversable , Iterator {
    /* Constants */
    const integer LEAVES_ONLY = 0 ;
    const integer SELF_FIRST = 1 ;
    const integer CHILD_FIRST = 2 ;
    const integer CATCH_GET_CHILD = 16 ;
    }
    

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35. $data = [
    'title' => 'how to work with iterators',
    'posts' => [
    [
    'title' => 'introduction to iterators',
    'email' => 'JohnDoe@example.com',
    ],
    [
    'title' => 'extending iterators',
    'email' => 'JaneDoe@example.com',
    ],
    ],
    ];
    $it = new RecursiveIteratorIterator(
    new RecursiveArrayIterator($data)
    );
    foreach($it as $field => $val) {
    echo "{$field}:{$val}\n";
    }
    Sub Title
    Recursive*Iterator
    Recursively Iterate Array
    

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36. $data = [
    'title' => 'how to work with iterators',
    'posts' => [
    [
    'title' => 'introduction to iterators',
    'email' => 'JohnDoe@example.com',
    ],
    [
    'title' => 'extending iterators',
    'email' => 'JaneDoe@example.com',
    ],
    ],
    ];
    $it = new RecursiveIteratorIterator(
    new RecursiveArrayIterator($data)
    );
    foreach($it as $field => $val) {
    echo "{$field}:{$val}\n";
    }
    Sub Title
    Recursive*Iterator
    Recursively Iterate Array
    title: how to work with iterators
    title: introduction to iterators
    email: JohnDoe@example.com
    title: extending iterators
    email: JaneDoe@example.com
    

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37. $it = new RecursiveArrayIterator([
    'Home',
    'About' => ['Careers', 'Contact'],
    'Location',
    'FAQ',
    ]);
    Sub Title
    RecursiveNavigationIterator Hooks
    Output multi-dimensional array as UL/LI
    

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38. class RecursiveNavigationIterator extends RecursiveIteratorIterator
    {
    public $openTag = "";
    public $closeTag = "";
    public function beginIteration()
    {
    echo $this->openTag . PHP_EOL;
    }
    public function endIteration()
    {
    echo $this->closeTag . PHP_EOL;
    }
    public function beginChildren()
    {
    echo $this->openTag . PHP_EOL;
    }
    public function endChildren()
    {
    echo $this->closeTag . PHP_EOL;
    }
    }
    Sub Title
    RecursiveNavigationIterator Hooks
    Output multi-dimensional array as UL/LI
    

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39. $it = new RecursiveArrayIterator([
    'Home',
    'About' => ['Careers', 'Contact'],
    'Location',
    'FAQ',
    ]);
    $navIt = new RecursiveNavigationIterator($it, RecursiveIteratorIterator::SELF_FIRST);
    foreach ($navIt as $navItem) {
    echo "{$navItem}" . PHP_EOL;
    }
    Sub Title
    RecursiveNavigationIterator Hooks
    Output multi-dimensional array as UL/LI
    

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40. $it = new RecursiveArrayIterator([
    'Home',
    'About' => ['Careers', 'Contact'],
    'Location',
    'FAQ',
    ]);
    $navIt = new RecursiveNavigationIterator($it, RecursiveIteratorIterator::SELF_FIRST);
    foreach ($navIt as $navItem) {
    echo "{$navItem}" . PHP_EOL;
    }
    Sub Title
    RecursiveNavigationIterator Hooks
    Output multi-dimensional array as UL/LI
    
    Home
    About
    
    Careers
    Contact
    
    Location
    FAQ
    
    

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41. Problem:
    Source: http://www.php.net/manual/en/spl.iterators.php
    I have a cache folder, but it goes
    many folders deep.
    

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42. $it = new RecursiveIteratorIterator(
    new RecursiveDirectoryIterator('cache', FilesystemIterator::SKIP_DOTS),
    RecursiveIteratorIterator::CHILD_FIRST
    );
    function clearCache(Iterator $it) {
    // Check if directory
    if ($it->current()->isDir()) {
    rmdir($it->key());
    return true;
    }
    return unlink($it->key());
    }
    iterator_apply($it, 'clearCache', [$it]);
    Sub Title
    iterator_apply
    Clear all files/folders in cache folder
    

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43. Directory Iterator
    

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44. $it = new DirectoryIterator('vendor');
    foreach ($it as $file) {
    echo $file->getFilename() . PHP_EOL;
    }
    Sub Title
    DirectoryIterator
    Source:
    Output directory content for Composer vendors
    http://us.php.net/manual/en/class.directoryiterator.php
    SplFileInfo
    

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45. $it = new DirectoryIterator('vendor');
    foreach ($it as $file) {
    echo $file->getFilename() . PHP_EOL;
    }
    Sub Title
    DirectoryIterator
    Source:
    Output directory content for Composer vendors
    http://us.php.net/manual/en/class.directoryiterator.php
    SplFileInfo
    .
    ..
    aura
    autoload.php
    bin
    composer
    monolog
    psr
    robmorgan
    slim
    slimcontroller
    symfony
    vlucas
    

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46. Directory Iterator Note
    If you attempt to access a file that you do
    not have permission to. You will receive a
    UnexpectedValueException.
    

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47. Filesystem Iterator
    

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48. FilesystemIterator
    extends DirectoryIterator
    implements SeekableIterator , Traversable , Iterator {
    /* Constants */
    const integer CURRENT_AS_PATHNAME = 32 ;
    const integer CURRENT_AS_FILEINFO = 0 ;
    const integer CURRENT_AS_SELF = 16 ;
    const integer CURRENT_MODE_MASK = 240 ;
    const integer KEY_AS_PATHNAME = 0 ;
    const integer KEY_AS_FILENAME = 256 ;
    const integer FOLLOW_SYMLINKS = 512 ;
    const integer KEY_MODE_MASK = 3840 ;
    const integer NEW_CURRENT_AND_KEY = 256 ;
    const integer SKIP_DOTS = 4096 ;
    const integer UNIX_PATHS = 8192 ;
    // Default Flags
    FilesystemIterator::KEY_AS_PATHNAME
    FilesystemIterator::CURRENT_AS_FILEINFO
    FilesystemIterator::SKIP_DOTS
    Sub Title
    FileSystemIterator (PHP 5.3.x)
    FileSystemIterator Constants/Flags
    

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49. Glob Iterator
    

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50. $it = new GlobIterator('vendor/*/*.php');
    foreach ($it as $path => $file) {
    echo $path . " - " . $file->getFilename() . PHP_EOL;
    }
    Sub Title
    GlobIterator
    Source:
    Output directory content for Composer vendors
    http://us.php.net/manual/en/class.globiterator.php
    

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51. $it = new GlobIterator('vendor/*/*.php');
    foreach ($it as $path => $file) {
    echo $path . " - " . $file->getFilename() . PHP_EOL;
    }
    Sub Title
    GlobIterator
    Source:
    Output directory content for Composer vendors
    http://us.php.net/manual/en/class.globiterator.php
    vendor/composer/ClassLoader.php - ClassLoader.php
    vendor/composer/autoload_classmap.php - autoload_classmap.php
    vendor/composer/autoload_namespaces.php - autoload_namespaces.php
    vendor/composer/autoload_psr4.php - autoload_psr4.php
    vendor/composer/autoload_real.php - autoload_real.php
    

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52. $it = new RecursiveDirectoryIterator('vendor');
    foreach (new RecursiveTreeIterator($it) as $file) {
    echo $file . PHP_EOL;
    }
    Sub Title
    RecursiveTreeIterator
    Source:
    Output ASCII view of Directory Structure
    http://us.php.net/manual/en/class.recursivetreeiterator.php
    

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53. $it = new RecursiveDirectoryIterator('vendor');
    foreach (new RecursiveTreeIterator($it) as $file) {
    echo $file . PHP_EOL;
    }
    Sub Title
    RecursiveTreeIterator
    Source:
    Output ASCII view of Directory Structure
    http://us.php.net/manual/en/class.recursivetreeiterator.php
    \-vendor/vlucas
    |-vendor/vlucas/.
    |-vendor/vlucas/..
    \-vendor/vlucas/phpdotenv
    |-vendor/vlucas/phpdotenv/.
    |-vendor/vlucas/phpdotenv/..
    |-vendor/vlucas/phpdotenv/.git
    | |-vendor/vlucas/phpdotenv/.git/.
    | |-vendor/vlucas/phpdotenv/.git/..
    | |-vendor/vlucas/phpdotenv/.git/FETCH_HEAD
    | |-vendor/vlucas/phpdotenv/.git/HEAD
    | |-vendor/vlucas/phpdotenv/.git/ORIG_HEAD
    | |-vendor/vlucas/phpdotenv/.git/branches
    | | |-vendor/vlucas/phpdotenv/.git/branches/.
    | | \-vendor/vlucas/phpdotenv/.git/branches/..
    | |-vendor/vlucas/phpdotenv/.git/config
    | |-vendor/vlucas/phpdotenv/.git/description
    

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54. Filter Iterator
    

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55. Source: http://www.php.net/manual/en/spl.iterators.php
    Need to view all files in a directory,
    but it keeps returning Version
    Control folders (.svn and .git).
    Problem:
    

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56. class NoVCSIterator extends FilterIterator
    {
    public function accept()
    {
    $vcsFolders = array(".git", ".svn");
    $file = $this->current();
    if ($file->isDir() && (in_array($vcsFolders, $file->getFilename())) {
    return false;
    }
    return true;
    }
    }
    Sub Title
    FilterIterator
    Do not show Version Control folders
    

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57. Source: http://www.php.net/manual/en/spl.iterators.php
    I need to see all images that are over
    5MB that have been uploaded.
    Problem:
    

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58. class LargeFileFilterIterator extends FilterIterator
    {
    public function accept()
    {
    $file = $this->current();
    if ($file->getSize() > $this->fileSizeMin) {
    return true;
    }
    return false;
    }
    }
    class ImageFilterIterator extends FilterIterator
    {
    public function accept()
    {
    $file = $this->current();
    if (in_array($file->getExtension(), $this->imageWhiteList)) {
    return true;
    }
    return false;
    }
    }
    Sub Title
    FilterIterator
    Only show images greater than 5MB
    

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59. $dir = new FileSystemIterator(UPLOADS_PATH);
    $filterIt = new LargeFileFilterIterator(
    new ImageFilterIterator($dir, ['jpg'])
    );
    foreach($filterIt as $file) {
    echo $file->getFileName() . PHP_EOL;
    }
    Sub Title
    FilterIterator
    Only show images greater than 5MB
    

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60. $dir = new FileSystemIterator(UPLOADS_PATH);
    $filterIt = new LargeFileFilterIterator(
    new ImageFilterIterator($dir, ['jpg'])
    );
    echo count($filterIt); // 1
    echo iterator_count($filterIt); // 2
    foreach($filterIt as $file) {
    echo $file->getFileName() . PHP_EOL;
    }
    Sub Title
    iterator_count
    Countable with Filters
    

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61. Regex Iterator
    

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62. /* Constants */
    const integer RegexIterator->MATCH = 0 ;
    const integer GET_MATCH = 1 ;
    const integer ALL_MATCHES = 2 ;
    const integer SPLIT = 3 ;
    const integer REPLACE = 4 ;
    const integer USE_KEY = 1 ;
    $it = new RecursiveDirectoryIterator(
    'vendor',
    RecursiveDirectoryIterator::SKIP_DOTS
    );
    $regexIt = new RecursiveRegexIterator(
    $it,
    '/^.*\.(php|env|json|yml)$/',
    RegexIterator::ALL_MATCHES
    );
    foreach (new RecursiveIteratorIterator($regexIt) as $path => $file) {
    echo $path . PHP_EOL;
    }
    Sub Title
    RegexIterator
    Source:
    Match specific file types with RecursiveDirectoryIterator
    http://us3.php.net/manual/en/class.regexiterator.php
    

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63. /* Constants */
    const integer RegexIterator->MATCH = 0 ;
    const integer GET_MATCH = 1 ;
    const integer ALL_MATCHES = 2 ;
    const integer SPLIT = 3 ;
    const integer REPLACE = 4 ;
    const integer USE_KEY = 1 ;
    $it = new RecursiveDirectoryIterator(
    'vendor',
    RecursiveDirectoryIterator::SKIP_DOTS
    );
    $regexIt = new RecursiveRegexIterator(
    $it,
    '/^.*\.(php|env|json|yml)$/',
    RegexIterator::ALL_MATCHES
    );
    foreach (new RecursiveIteratorIterator($regexIt) as $path => $file) {
    echo $path . PHP_EOL;
    }
    Sub Title
    RegexIterator
    Source:
    Match specific file types with RecursiveDirectoryIterator
    http://us3.php.net/manual/en/class.regexiterator.php
    vendor/autoload.php
    vendor/composer/ClassLoader.php
    vendor/composer/autoload_classmap.php
    vendor/composer/autoload_namespaces.php
    vendor/composer/autoload_psr4.php
    vendor/composer/autoload_real.php
    vendor/composer/installed.json
    

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64. Parent Iterator
    

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65. Source: http://www.php.net/manual/en/spl.iterators.php
    Parent Iterator is a FilterIterator
    that only accepts elements that
    have children. Hence the name
    ParentIterator
    Parent Iterator
    

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66. Limit Iterator
    

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67. Source: http://www.php.net/manual/en/spl.iterators.php
    Currently have a CSV with a lot of
    lines, but I need to paginate
    with 3 results per page.
    Problem:
    

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68. $usersCSV = <<"jsmith", "Jake", "Smith", "jake.smith92@gmail.com"
    "saustin", "Steve", "Austin", "moneyman@gmail.com"
    "srogers", "Steven", "Rogers", "thecapt@gmail.com"
    "ballen", "Barry", "Allen", "ballen@flash.net"
    "bbanner", "Bruce", "Banner", "smashallthethings@gmail.com"
    CSV;
    $csv = new SplTempFileObject();
    $csv->fwrite($usersCSV);
    $csv->setFlags(SplFileObject::READ_CSV);
    $it = new LimitIterator($csv, 0, 3);
    foreach ($it as list($username, $firstName, $lastName, $email)) {
    echo "{$firstName} {$lastName}" . PHP_EOL;
    }
    Sub Title
    LimitIterator
    Limit CSV output to first 3
    

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69. $usersCSV = <<"jsmith", "Jake", "Smith", "jake.smith92@gmail.com"
    "saustin", "Steve", "Austin", "moneyman@gmail.com"
    "srogers", "Steven", "Rogers", "thecapt@gmail.com"
    "ballen", "Barry", "Allen", "ballen@flash.net"
    "bbanner", "Bruce", "Banner", "smashallthethings@gmail.com"
    CSV;
    $csv = new SplTempFileObject();
    $csv->fwrite($usersCSV);
    $csv->setFlags(SplFileObject::READ_CSV);
    $it = new LimitIterator($csv, 0, 3);
    foreach ($it as list($username, $firstName, $lastName, $email)) {
    echo "{$firstName} {$lastName}" . PHP_EOL;
    }
    Sub Title
    LimitIterator
    Limit CSV output to first 3
    Jake Smith
    Steve Austin
    Steven Rogers
    

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70. $usersCSV = <<"jsmith", "Jake", "Smith", "jake.smith92@gmail.com"
    "saustin", "Steve", "Austin", "moneyman@gmail.com"
    "srogers", "Steven", "Rogers", "thecapt@gmail.com"
    "ballen", "Barry", "Allen", "ballen@flash.net"
    "bbanner", "Bruce", "Banner", "smashallthethings@gmail.com"
    CSV;
    $csv = new SplTempFileObject();
    $csv->fwrite($usersCSV);
    $csv->setFlags(SplFileObject::READ_CSV);
    $it = new LimitIterator($csv, 0, 3);
    try {
    $it->seek(20);
    } catch (OutOfBoundsException $e) {
    echo "Error: " . $e->getMessage() . PHP_EOL;
    }
    Sub Title
    LimitIterator
    Throw Exception if seeking beyond total number of elements
    

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71. $usersCSV = <<"jsmith", "Jake", "Smith", "jake.smith92@gmail.com"
    "saustin", "Steve", "Austin", "moneyman@gmail.com"
    "srogers", "Steven", "Rogers", "thecapt@gmail.com"
    "ballen", "Barry", "Allen", "ballen@flash.net"
    "bbanner", "Bruce", "Banner", "smashallthethings@gmail.com"
    CSV;
    $csv = new SplTempFileObject();
    $csv->fwrite($usersCSV);
    $csv->setFlags(SplFileObject::READ_CSV);
    $it = new LimitIterator($csv, 0, 3);
    try {
    $it->seek(20);
    } catch (OutOfBoundsException $e) {
    echo "Error: " . $e->getMessage() . PHP_EOL;
    }
    Sub Title
    LimitIterator
    Throw Exception if seeking beyond total number of elements
    Error: Cannot seek to 20 which is behind offset 0 plus count 3
    

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72. Callback Filter
    Iterator
    

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73. Source: http://www.php.net/manual/en/spl.iterators.php
    I need to find all files that contain
    the word “recursive”, but don’t
    want to create a new class to
    extend FilterIterator.
    Problem:
    

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74. $dirIt = new GlobIterator('*.php');
    $recursiveFiles = new CallbackFilterIterator(
    $dirIt,
    function($current, $key, $it) {
    return preg_match('/recursive/i', $current);
    }
    );
    foreach($recursiveFiles as $name) {
    echo $name . PHP_EOL;
    }
    Sub Title
    CallbackFilterIterator
    CallbackFilterIterator requires PHP 5.4
    

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75. $dirIt = new GlobIterator('*.php');
    $recursiveFiles = new CallbackFilterIterator(
    $dirIt,
    function($current, $key, $it) {
    return preg_match('/recursive/i', $current);
    }
    );
    foreach($recursiveFiles as $name) {
    echo $name . PHP_EOL;
    }
    Sub Title
    CallbackFilterIterator
    CallbackFilterIterator requires PHP 5.4
    /recursive_cache.php
    /recursive_it.php
    

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76. Caching Iterator
    

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77. Source: http://www.php.net/manual/en/spl.iterators.php
    I need to know what value of the
    next element will be. Think prev/
    next navigation.
    Problem:
    

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78. $articles = new ArrayIterator([
    'NetTuts.com: Integrating Zendesk With WordPress',
    'Laravel News: The Artisan Files Alex Dover',
    'That Podcast: Episode 10 The one with the "best practices"',
    'Community News: Packagist Latest Releases for 11.14.2014',
    ]);
    $it = new CachingIterator($articles);
    $it->rewind();
    foreach ($it as $article) {
    echo "{$article}";
    if ($it->hasNext()) {
    echo " --- {$it->getInnerIterator()->current()}";
    }
    echo PHP_EOL;
    }
    Sub Title
    CachingIterator
    CachingIterator? Look Ahead Iterator!
    Source: http://stackoverflow.com/questions/2458099/peek-ahead-when-iterating-an-array-in-php-5-2
    

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79. $articles = new ArrayIterator([
    'NetTuts.com: Integrating Zendesk With WordPress',
    'Laravel News: The Artisan Files Alex Dover',
    'That Podcast: Episode 10 The one with the "best practices"',
    'Community News: Packagist Latest Releases for 11.14.2014',
    ]);
    $it = new CachingIterator($articles);
    $it->rewind();
    foreach ($it as $article) {
    echo "{$article}";
    if ($it->hasNext()) {
    echo " --- {$it->getInnerIterator()->current()}";
    }
    echo PHP_EOL;
    }
    Sub Title
    CachingIterator
    CachingIterator? Look Ahead Iterator!
    Source: http://stackoverflow.com/questions/2458099/peek-ahead-when-iterating-an-array-in-php-5-2
    NetTuts.com: Integrating Zendesk With WordPress --- Laravel News: The Artisan Files Alex
    Dover
    Laravel News: The Artisan Files Alex Dover --- That Podcast: Episode 10 The one with the
    "best practices"
    That Podcast: Episode 10 The one with the "best practices" --- Community News: Packagist
    Latest Releases for 11.14.2014
    Community News: Packagist Latest Releases for 11.14.2014
    

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80. Generators
    

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81. function getLines($file) {
    $f = fopen($file, 'r');
    if (!$f) throw new Exception();
    while ($line = fgets($f)) {
    yield $line;
    }
    fclose($f);
    }
    Sub Title
    Generator
    We Have a Generator
    http://blog.ircmaxell.com/2012/07/what-generators-can-do-for-you.html
    It’s really that easy!
    

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82. NOW IN PHP
    

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83. function easyAsAbc() {
    yield 1;
    yield 2;
    yield 3;
    }
    foreach (easyAsAbc() as $num) {
    echo $num . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    

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84. function easyAsAbc() {
    yield 1;
    yield 2;
    yield 3;
    }
    foreach (easyAsAbc() as $num) {
    echo $num . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    1
    2
    3
    

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85. function easyAsAbc() {
    yield 1;
    return;
    yield 2;
    yield 3;
    }
    foreach (easyAsAbc() as $num) {
    echo $num . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    End an iteration
    

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86. function easyAsAbc() {
    yield 1;
    return;
    yield 2;
    yield 3;
    }
    foreach (easyAsAbc() as $num) {
    echo $num . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    End an iteration
    1
    

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87. function easyAsAbc() {
    yield 1;
    return true;
    yield 2;
    yield 3;
    }
    foreach (easyAsAbc() as $num) {
    echo $num . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    Returning a value
    will cause a PHP Fatal
    Returning ANY VALUE will cause a PHP Fatal
    

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88. function easyAsAbc() {
    yield 1;
    return true;
    yield 2;
    yield 3;
    }
    foreach (easyAsAbc() as $num) {
    echo $num . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    Returning a value
    will cause a PHP Fatal
    Returning ANY VALUE will cause a PHP Fatal
    PHP Fatal error: Generators cannot return values using "return"
    

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89. function userAttributes() {
    yield 'id' => 1;
    yield 'username' => 'jsmith';
    yield 'email' => 'jake.smith92@gmail.com';
    }
    foreach (userAttributes() as $key => $val) {
    echo $key . ':' . $val . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    Key and Value yield
    

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90. function userAttributes() {
    yield 'id' => 1;
    yield 'username' => 'jsmith';
    yield 'email' => 'jake.smith92@gmail.com';
    }
    foreach (userAttributes() as $key => $val) {
    echo $key . ':' . $val . PHP_EOL;
    }
    Sub Title
    Quick Tips with Yield
    http://us3.php.net/manual/en/language.generators.syntax.php
    Key and Value yield
    id:1
    username:jsmith
    email:jake.smith92@gmail.com
    

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91. function counter($start) {
    for ($i = $start; $i >= $start; $i++) {
    $command = (yield $i);
    if ($command == "stop") {
    return;
    }
    }
    }
    $counter = counter(1);
    foreach ($counter as $num) {
    if ($num >= 20) {
    $counter->send('stop');
    }
    echo $num . PHP_EOL;
    }
    Receive data
    Quick Tips with Yield
    

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92. function counter($start) {
    for ($i = $start; $i >= $start; $i++) {
    $command = (yield $i);
    if ($command == "stop") {
    return;
    }
    }
    }
    $counter = counter(1);
    foreach ($counter as $num) {
    if ($num >= 20) {
    $counter->send('stop');
    }
    echo $num . PHP_EOL;
    }
    Receive data
    Quick Tips with Yield
    

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93. function counter($start) {
    for ($i = $start; $i >= $start; $i++) {
    $command = (yield $i);
    if ($command == "stop") {
    return;
    }
    }
    }
    $counter = counter(1);
    foreach ($counter as $num) {
    if ($num >= 20) {
    $counter->send('stop');
    }
    echo $num . PHP_EOL;
    }
    Receive data
    Quick Tips with Yield
    Receiving values via
    send method
    

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94. function counter($start) {
    for ($i = $start; $i >= $start; $i++) {
    $command = (yield $i);
    if ($command == "stop") {
    return;
    }
    }
    }
    $counter = counter(1);
    foreach ($counter as $num) {
    if ($num >= 20) {
    $counter->send('stop');
    }
    echo $num . PHP_EOL;
    }
    Receive data
    Quick Tips with Yield
    Receiving values via
    send method
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    

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95. Other Iterators
    

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96. Other Iterators
    •EmptyIterator
    •If you try to access current() it
    will throw an Exception
    •InfiniteIterator
    •Continuously runs (auto rewinds)
    

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97. Iterator Functions
    

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98. Iterator Functions
    • iterator_to_array
    • If Iterator is Recursive, it will flatten array
    • iterator_apply
    • similar to array_walk
    • iterator_count
    • used when iterator doesn’t implement
    countable
    

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99. Questions?
    Concerns?
    Complaints?
    

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100. https://joind.in/12807
     

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101. jakefolio
     http://jakefolio.com
     me@jakefolio.com
     Jake Smith
     Thanks for Listening!
     

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