Collection

Collection is a library geared towards delivering a fast and intuitive interface over a group of related elements.

Defining a Collection

Collections can be constructed in multiple ways by passing:

• an integer to the constructor indicating its capacity
• an array or SplFixedArray containing the elements of the collection

Defining an Empty Collection

Empty collections are created by passing an integer to the Collection constructor indicating its capacity. All indexes of the collection are initalized to null and the size of the collection is reported as 0.

$imEmpty = new Collection(10);

count($imEmpty);
// 0

Defining a Collection Derived From An array or SplFixedArray

Collections can be defined using a populated array (or SplFixedArray) simply by passing the array to Collection constructor. The size of the Collection is determined by finding the last non-null index of the array.

$daysOfTheWeek = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
$fromArray = new Collection($daysOfTheWeek);

count($fromArray);
// 7

$occupations = new \SplFixedArray(10);
$occupations[0] = 'Botanist';

$occupations = new Collection($occupations);

count($occupations);
// 1

Using Collection

map($func)

Use map to create a new instance of Collection which contains a projection of each element of the mapped collection. The projection is created by applying the function contained in $func to each element of the original collection.

Parameters

`$func`

The function which is applied to each element of the collection. `$func` can be any [callable](callable) function.

Example

// using a function name
$words = new Collection(['Lorem', 'ipsum', 'dolor', 'sit' 'amet']);
$shouty = $words->map('strtoupper');
// ['LOREM', 'IPSUM', 'DOLOR', 'SIT' 'AMET'];

// using a callable array
$classesToMock = new Collection(['SomeClass', 'SomeOtherClass', 'YetAnotherClass']);
$mocks = $classesToMack->map(['Mockery', 'mock']);
//[object(Mockery\Mock), object(Mockery\Mock), object(Mockery\Mock)]

// using an anonymous function
$stringyDates = new Collection(['2007-06-08', '2009-05-11', '2014-02-19']);
$dates = $stringyDates->map(function ($date) {
  return DateTime::createFromFormat('Y-m-d', $date);
});
// [object(DateTime), object(DateTime), object(DateTime)]

each($func)

Apply $func to each element of the collection. each returns the original collection so you can chain other methods off of it.

Parameters

`$func`

The function which is applied to each element of the collection. `$func` can be any [callable](callable) function.

Example

$queueEmail = function ($address) use ($message, $emailQueue) {
    $emailQueue->publish(['to' => $address, 'message' => $message]);
};

$adminEmails->each($queueEmail);

reduce($func, $intial)

Generate a single aggregate value derived from applying $func to each element of the collection.

Parameters

`$func`

The reducer function, this function accepts two parameters, `$carry` and `$elem` (in that order) where `$carry` is the current value of the reduction and `$elem` is the current element in the collection being reduced. `$func` can be any [callable](callable) function.

`$initial`

The initial value to be used in the reduction

Example

$workSchedule = new Collection([
     ['date' => '2015/04/20', 'start' => '08:00', 'end' => '12:00'],
     ['date' => '2015/04/21', 'start' => '12:00', 'end' => '17:00'],
     ['date' => '2015/04/23', 'start' => '08:00', 'end' => '17:00'],
     ['date' => '2015/04/24', 'start' => '10:00', 'end' => '15:00']
]);

$totalHours = $workSchedule->reduce(function($total, $schedule) {
    $start = DateTime::createFromFormat('Y/m/d H:i', $schedule['date'] . ' ' . $schedule['start']);
    $end = DateTime::createFromFormat('Y/m/d H:i', $schedule['date'] . ' ' . $schedule['end']);
    $hours = $end->diff($start)->h;
    return $total + $hours;
});
// 25

filter($func = null)

Return a new Collection containing the elements for which $func returns true. If $func is not passed to filter then only truthy values contained in the original collection will be present in the result.

Parameters

`$func`

The filter function for which each element of the collection is passed through. `$func` returns `true` if the element should be kept and `false` if not.

Example

$workSchedule = new Collection([
     ['date' => '2015/04/20', 'start' => '08:00', 'end' => '12:00'],
     ['date' => '2015/04/21', 'start' => '12:00', 'end' => '17:00'],
     ['date' => '2015/04/23', 'start' => '08:00', 'end' => '17:00'],
     ['date' => '2015/04/24', 'start' => '10:00', 'end' => '15:00']
]);

$packALunch = $workSchedule->filter(function($schedule) {
    $start = DateTime::createFromFormat('Y/m/d H:i', $schedule['date'] . ' ' . $schedule['start']);
    $end = DateTime::createFromFormat('Y/m/d H:i', $schedule['date'] . ' ' . $schedule['end']);
    $hours = $end->diff($start)->h;
    return $hours > 4;
});
// object(Collection)(
     ['date' => '2015/04/21', 'start' => '12:00', 'end' => '17:00'],
     ['date' => '2015/04/23', 'start' => '08:00', 'end' => '17:00'],
     ['date' => '2015/04/24', 'start' => '10:00', 'end' => '15:00']
)

slice($offset, $length = null)

flatten($flattenWith = null)

Transform a multi-dimensional collection into a one dimensional collection. The responsibilty of $flattenWith is to accept an element of the collection and return an arrray (or an object that implements both Countable and ArrayAccess) of the elements contained within that element. If a flattenWith function is not provided to flatten then the method will attempt to flatten the collection using a generic flattenWith function, this is useful for flattening a 2 dimensional collection.

Parameters

`$func`

This function is used to flatten individual elements into single dimensional array.

Example

contains($value)

first($matching = null)

last($matching = null)

reverse()

groupBy($getGroupKey)

prepend($elem)

append($elem)

push($elem)

pop()

toArray()

count()

Author

Colin DeCarlo, colin@thedecarlos.ca

License

Collection is licensed under the MIT License - see the LICENSE file for details