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Iterators IN PHP NOW WITH GENERATORS

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http://bitly.com/wNwg6N

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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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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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One Iterator Two Iterator Three Iterator floor();

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Where are Iterators Used?

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

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Everyone Loves Iterators

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Everyone Loves Iterators Have you used SimpleXML?

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

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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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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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Defining an Iterator

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Iterator Interfaces

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

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

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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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Iterator Basics

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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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Iterator Aggregate Iterator Aggregate Iterator

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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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Outer Iterator Outer Iterator Inner Iterator

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Outer Iterator Outer Iterator Inner Iterator

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

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Recursive Iterator Recursive Iterator Get Children

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

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Recursive Iterators

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

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$data = [ 'title' => 'how to work with iterators', 'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; foreach (new RecursiveArrayIterator($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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$data = [ 'title' => 'how to work with iterators', 'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; foreach (new RecursiveArrayIterator($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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No content

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

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$data = [ 'title' => 'how to work with iterators', 'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; $it = new RecursiveIteratorIterator( new RecursiveArrayIterator($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: [email protected] title: extending iterators email: [email protected]

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

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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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$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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    $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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    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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    $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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    Directory Iterator

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    $it = new DirectoryIterator('vendor'); foreach ($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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    $it = new DirectoryIterator('vendor'); foreach ($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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    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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    Filesystem Iterator

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    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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    Glob Iterator

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    $it = new GlobIterator('vendor/*/*.php'); foreach ($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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    $it = new GlobIterator('vendor/*/*.php'); foreach ($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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    $it = new RecursiveDirectoryIterator('vendor'); foreach (new RecursiveTreeIterator($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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    $it = new RecursiveDirectoryIterator('vendor'); foreach (new RecursiveTreeIterator($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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    Filter Iterator

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    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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    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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    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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    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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    $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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    $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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    Regex Iterator

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    /* 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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    /* 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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    Parent Iterator

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    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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    Limit Iterator

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    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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    $usersCSV = <<fwrite($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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    $usersCSV = <<fwrite($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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    $usersCSV = <<fwrite($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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    $usersCSV = <<fwrite($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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    Callback Filter Iterator

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    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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    $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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    $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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    Caching Iterator

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    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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    $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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    $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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    Generators

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    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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    NOW IN PHP

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    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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    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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    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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    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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    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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    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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    function userAttributes() { yield 'id' => 1; yield 'username' => 'jsmith'; yield 'email' => '[email protected]'; } 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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    function userAttributes() { yield 'id' => 1; yield 'username' => 'jsmith'; yield 'email' => '[email protected]'; } 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:[email protected]

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    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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    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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    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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    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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    Other Iterators

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

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    Iterator Functions

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    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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    Questions? Concerns? Complaints?

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    https://joind.in/12807

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    jakefolio http://jakefolio.com [email protected] Jake Smith Thanks for Listening!