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Hoa

Hack book of Hoa\Iterator

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This library provides a set of useful iterator (compatible with PHP iterators). Existing PHP iterators have been updated to get new features and prior PHP versions compatibility.

Learn more.

Quick usage

We propose a quick overview of all iterators.

The One

Hoa\Iterator\Iterator defines the basis of an iterator. It extends Iterator.

External iterator

Hoa\Iterator\Aggregate allows a class to use an external iterator through the getIterator method. It extends IteratorAggregate

Traversable to iterator

Hoa\Iterator\IteratorIterator transforms anything that is traversable into an iterator. It extends IteratorIterator.

Iterator of iterators

Hoa\Iterator\Outer represents an iterator that iterates over iterators. It extends OuterIterator.

Mock

Hoa\Iterator\Mock represents an empty iterator. It extends EmptyIterator.

Seekable

Hoa\Iterator\Seekable represents an iterator that can be seeked. It extends SeekableIterator.

Map

Hoa\Iterator\Map allows to iterate an array. It extends ArrayIterator.

$foobar = new Hoa\Iterator\Map(['f', 'o', 'o', 'b', 'a', 'r']);

foreach ($foobar as $value) {
    echo $value;
}

/**
 * Will output:
 *     foobar
 */

Filters

Hoa\Iterator\Filter and Hoa\Iterator\CallbackFilter allows to filter the content of an iterator. It extends FilterIterator and CallbackFilterIterator.

$filter = new Hoa\Iterator\CallbackFilter(
    $foobar,
    function ($value, $key, $iterator) {
        return false === in_array($value, ['a', 'e', 'i', 'o', 'u']);
    }
);

foreach ($filter as $value) {
    echo $value;
}

/**
 * Will output:
 *     fbr
 */

Also, Hoa\Iterator\RegularExpression allows to filter based on a regular expression.

Limit

Hoa\Iterator\Limit allows to iterate n elements of an iterator starting from a specific offset. It extends LimitIterator.

$limit = new Hoa\Iterator\Limit($foobar, 2, 3);

foreach ($limit as $value) {
    echo $value;
}

/**
 * Will output:
 *     oba
 */

Infinity

Hoa\Iterator\Infinite allows to iterate over and over again the same iterator. It extends InfiniteIterator.

$infinite = new Hoa\Iterator\Infinite($foobar);
$limit    = new Hoa\Iterator\Limit($infinite, 0, 21);

foreach ($limit as $value) {
    echo $value;
}

/**
 * Will output:
 *     foobarfoobarfoobarfoo
 */

Also, Hoa\Iterator\NoRewind is an iterator that does not rewind. It extends NoRewindIterator.

Repeater

Hoa\Iterator\Repeater allows to repeat an iterator n times.

$repeater = new Hoa\Iterator\Repeater(
    $foobar,
    3,
    function ($i) {
        echo "\n";
    }
);

foreach ($repeater as $value) {
    echo $value;
}

/**
 * Will output:
 *     foobar
 *     foobar
 *     foobar
 */

Counter

Hoa\Iterator\Counter is equivalent to a for($i = $from, $i < $to, $i += $step) loop.

$counter = new Hoa\Iterator\Counter(0, 12, 3);

foreach ($counter as $value) {
    echo $value, ' ';
}

/**
 * Will output:
 *     0 3 6 9
 */

Union of iterators

Hoa\Iterator\Append allows to iterate over iterators one after another. It extends AppendIterator.

$counter1 = new Hoa\Iterator\Counter(0, 12, 3);
$counter2 = new Hoa\Iterator\Counter(13, 23, 2);
$append   = new Hoa\Iterator\Append();
$append->append($counter1);
$append->append($counter2);

foreach ($append as $value) {
    echo $value, ' ';
}

/**
 * Will output:
 *     0 3 6 9 13 15 17 19 21 
 */

Multiple

Hoa\Iterator\Multiple allows to iterate over several iterator at the same times. It extends MultipleIterator.

$foobar   = new Hoa\Iterator\Map(['f', 'o', 'o', 'b', 'a', 'r']);
$baz      = new Hoa\Iterator\Map(['b', 'a', 'z']);
$multiple = new Hoa\Iterator\Multiple(
    Hoa\Iterator\Multiple::MIT_NEED_ANY
  | Hoa\Iterator\Multiple::MIT_KEYS_ASSOC
);
$multiple->attachIterator($foobar, 'one', '!');
$multiple->attachIterator($baz,    'two', '?');

foreach ($multiple as $iterators) {
    echo $iterators['one'], ' | ', $iterators['two'], "\n";
}

/**
 * Will output:
 *     f | b
 *     o | a
 *     o | z
 *     b | ?
 *     a | ?
 *     r | ?
 */

Demultiplexer

Hoa\Iterator\Demultiplexer demuxes result from another iterator. This iterator is somehow the opposite of the Hoa\Iterator\Multiple iterator.

$counter  = new Hoa\Iterator\Counter(0, 10, 1);
$multiple = new Hoa\Iterator\Multiple();
$multiple->attachIterator($counter);
$multiple->attachIterator(clone $counter);
$demultiplexer = new Hoa\Iterator\Demultiplexer(
    $multiple,
    function ($current) {
        return $current[0] * $current[1];
    }
);

foreach ($demultiplexer as $value) {
    echo $value, ' ';
}

/**
 * Will output:
 *     0 1 4 9 16 25 36 49 64 81 
 */

File system

Hoa\Iterator\Directory and Hoa\Iterator\FileSystem allow to iterate the file system where files are represented by instances of Hoa\Iterator\SplFileInfo. They respectively extend DirectoryIterator, FilesystemIterator and SplFileInfo.

$directory = new Hoa\Iterator\Directory(resolve('hoa://Library/Iterator'));

foreach ($directory as $value) {
    echo $value->getFilename(), "\n";
}

/**
 * Will output:
 *     .
 *     ..
 *     .State
 *     Aggregate.php
 *     Append.php
 *     CallbackFilter.php
 *     composer.json
 *     Counter.php
 *     Demultiplexer.php
 *     …
 */

Also, the Hoa\Iterator\Glob allows to iterator with the glob strategy. It extends GlobIterator. Thus:

$glob = new Hoa\Iterator\Glob(resolve('hoa://Library/Iterator') . '/M*.php');

foreach ($glob as $value) {
    echo $value->getFilename(), "\n";
}

/**
 * Will output:
 *     Map.php
 *     Mock.php
 *     Multiple.php
 */

Look ahead

Hoa\Iterator\Lookahead allows to look ahead for the next element:

$counter   = new Hoa\Iterator\Counter(0, 5, 1);
$lookahead = new Hoa\Iterator\Lookahead($counter);

foreach ($lookahead as $value) {
    echo $value;

    if (true === $lookahead->hasNext()) {
        echo ' (next: ', $lookahead->getNext(), ')';
    }

    echo "\n";
}

/**
 * Will output:
 *     0 (next: 1)
 *     1 (next: 2)
 *     2 (next: 3)
 *     3 (next: 4)
 *     4
 */

The Hoa\Iterator\Lookbehind also exists and allows to look behind for the previous element.

Buffer

Hoa\Iterator\Buffer allows to move forward as usual but also backward up to a given buffer size over another iterator:

$abcde  = new Hoa\Iterator\Map(['a', 'b', 'c', 'd', 'e']);
$buffer = new Hoa\Iterator\Buffer($abcde, 3);

$buffer->rewind();
echo $buffer->current(); // a

$buffer->next();
echo $buffer->current(); // b

$buffer->next();
echo $buffer->current(); // c

$buffer->previous();
echo $buffer->current(); // b

$buffer->previous();
echo $buffer->current(); // a

$buffer->next();
echo $buffer->current(); // b

/**
 * Will output:
 *     abcbab
 */

Callback generator

Hoa\Iterator\CallbackGenerator allows to transform any callable into an iterator. This is very useful when combined with other iterators, for instance with Hoa\Iterator\Limit:

$generator = new Hoa\Iterator\CallbackGenerator(function ($key) {
    return mt_rand($key, $key * 2);
});
$limit = new Hoa\Iterator\Limit($generator, 0, 10);

foreach ($limit as $value) {
    echo $value, ' ';
}

/**
 * Could output:
 *     0 2 3 4 4 7 8 10 12 18 
 */

Recursive iterators

A recursive iterator is an iterator where its values is other iterators. The most important interface is Hoa\Iterator\Recursive\Recursive (it extends RecursiveIterator). Then we find (in alphabetic order):

An error or a suggestion about the documentation? Contributions are welcome!

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