SPL filtering values

callback_filter.php

<?php

$courses = simplexml_load_file('common/data/courses.xml', 'SimpleXMLIterator');

$courses = new CallbackFilterIterator($courses, 'getCoursesByLevel');

foreach ($courses as $course) {
    echo "$course->title with $course->author (level: $course->level)<br />";
}

function getCoursesByLevel($current)
{
    return strtolower($current->level) == 'beginner';
}

filter.php

<?php

class AuthorFilter extends FilterIterator
{
    protected $author;

    public function __construct(Iterator $iterator, $author)
    {
        parent::__construct($iterator);
        $this->author = $author;
    }

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

$courses = simplexml_load_file('common/data/courses.xml', 'SimpleXMLIterator');
$courses = new AuthorFilter($courses, 'David Powers');

foreach ($courses as $course) {
    echo "$course->title by author <b>$course->author</b><br />";
}

glob.php

<?php

$files = new GlobIterator(__DIR__ . '/common/images/*.jpg');

foreach ($files as $file) {
    echo $file->getFilename() . '<br />';
}

limit.php

<?php

$courses = simplexml_load_file('common/data/courses.xml', 'SimpleXMLIterator');
$courses = new LimitIterator($courses, 10, 5);
foreach ($courses as $course) {
    echo $courses->getPosition() + 1 . ".$course->title with $course->author (duration: $course->duration)<br />";
}

parent.php

<?php

$dirs = new RecursiveDirectoryIterator('.');
$dirs = new ParentIterator($dirs);
$dirs = new RecursiveIteratorIterator($dirs, RecursiveIteratorIterator::SELF_FIRST);

foreach ($dirs as $dir) {
    echo $dir->getPathname() . '<br />';
}

recursive_callback.php

<?php

$files = new RecursiveDirectoryIterator('common');
$files->setFlags(RecursiveDirectoryIterator::SKIP_DOTS);
$files = new RecursiveCallbackFilterIterator($files, function ($current, $key, $iterator) {
    if ($iterator->hasChildren()) {
        return true;
    }

    return $current->getSize() > 1024 * 6;
});

$files = new RecursiveIteratorIterator($files);
foreach ($files as $file) {
    echo $file->getPathname() . ' is ' . round($file->getSize() / 1024, 1) . 'kb<br />';
}

recursive_filter.php

<?php

class FilterByExtension extends RecursiveFilterIterator
{
    protected $extensions;

    public function __construct(RecursiveIterator $iterator, $extensions)
    {
        parent::__construct($iterator);
        $this->extensions = is_array($extensions) ? $extensions : (array) $extensions;
    }
    
    public function accept()
    {
        if ($this->hasChildren()) {
            return true;
        }
        $images = ['png', 'jpg', 'gif', 'webp'];

        return $this->current()->isFile() and in_array(strtolower($this->current()->getExtension()), $this->extensions);
    }

    public function getChildren()
    {
        return new self($this->getInnerIterator()->getChildren(), $this->extensions);
    }
}

$files = new RecursiveDirectoryIterator('.');
$files->setFlags(FilesystemIterator::UNIX_PATHS);
$files = new FilterByExtension($files, ['png', 'xml']);
$files = new RecursiveIteratorIterator($files);
foreach ($files as $file) {
    echo $file->getPathname() . '<br />';
}

regex.php

<?php

$files = new RecursiveDirectoryIterator('.', FilesystemIterator::UNIX_PATHS);
$files = new RecursiveIteratorIterator($files);
$files = new RegexIterator($files, '/\.(?:csv|docx)$/i');

foreach ($files as $file) {
    echo $file->getPathname() . '<br />';
}

simplexml.php

<?php

$courses = simplexml_load_file('common/data/courses.xml', 'SimpleXMLIterator');

foreach ($courses as $course) {
    $matches = new RegexIterator($course->author, '/joh?n peck/i');
    var_dump($matches);
    foreach ($matches as $match) {
        echo $course->title . ' with ' . $match . ' (Duration: ' . $course->duration . ')<br />';
    }
}