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Awesome Open Source


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1. Introduction

This PHP extension provides a set of useful and convenient operations on PHP arrays, which makes working with arrays simple and scalable.

Method names and functionalities are inspired by Kotlin.Collections, having a slightly different style than that of Laravel Collections.

Requires PHP version >= 7.1 and < 8.0 (master branch).

1.1 Example

Here is a simple example on how to work with arrays gracefully using this extension.

$employees = [
    ['name' => 'Alice',    'gender' => 'female', 'age' => 35],
    ['name' => 'Bob',      'gender' => 'male',   'age' => 29],
    ['name' => 'David',    'gender' => 'male',   'age' => 40],
    ['name' => 'Benjamin', 'gender' => 'male',   'age' => 32]
// Trying to get an array of names of male employees,
// sorted by the descending order of their age.
$names = Collection::init($employees)
    ->filter(function ($value) {
        return $value['gender'] == 'male';
    ->sortedByDescending(function ($value) {
        return $value['age'];
    ->map(function ($value) {
        return $value['name'];
// You got $names == ['David', 'Benjamin', 'Bob'].

2. Getting Started

2.1 Installation

Like other PHP extensions, ext-collections can be built and installed with a few commands:

sudo make install

Include it in your PHP configuration file to enable this extension:

Building on Windows is not as convenient, however, pre-built binaries for Windows are provided in the releases. If you want to build it yourself, follow the official PHP wiki.

2.2 API Reference

See stubs directory for signatures of all classes and methods of this extension, with PHPDoc. They can also serve as IDE helper.

2.3 PHP-style Access

The Collection class implements ArrayAccess and Countable interface internally, you can treat an instance of Collection as an ArrayObject.

  • The isset(), unset() keywords can be used on elements of Collection.
  • Elements can be accessed via property or bracket expression.
  • empty(), count() can be used on instance of Collection.
  • Elements can be traversed via foreach() keyword.

3. Notes

  • The Collection::xxxTo() methods will preserve the original key-value pairs of destination Collection when keys collide.
  • Some methods of Collection involves comparing two of its elements, which accepts $flags as one of its arguments. When these methods are being invoked, make sure all elements are of the same type (numeric/string/others), otherwise you're likely to get a segfault.

3.1 Copy-on-write Mechanism

Class Collection does not introduce new data structures internally. Instead, it only holds a pointer to a zend_array, and all its methods works directly on top of zend_array. Which means conversion between Collection and array does not involve copying, until write operation is performed on one of the duplicates.

$foo = ['a', 'b'];              // arr0: refcount = 1
$bar = Collection::init($foo);  // arr0: refcount = 2, no copying of either `zend_array` or its elements
echo $bar->containsValue('a');  // arr0: refcount = 2, read operation, no copying
$bar->shuffle();                // arr0: refcount = 1, arr1: refcount = 1, write operation, `zend_array` is separated
$baz = $bar->toArray();         // arr0: refcount = 1, arr1: refcount = 2, no copying

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