Dark Corners Of The SPL

Dark Corners Of The SPL

PHP is a huge language, with lots of "kitchen sink" functionality for you to build data structures with. But did you know PHP includes a standard library that has built-in structures like linked lists, queues, stacks, and higher-performance arrays? This talk will cover a few of the more interesting ones in depth, including how to use them and most importantly why you'd use them over other solutions.

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Omni Adams

August 16, 2018
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  1. Dark Corners of the SPL Photo By: SSG Ryan Boas

  2. Photo By: Tom Walsh

  3. Photo By: NASA Goddard Space Flight Center

  4. Data Structures SplDoublyLinkedList SplStack SplQueue SplHeap SplMaxHeap SplMinHeap SplPriorityQueue SplFixedArray

    SplObjectStorage https://secure.php.net/manual/en/spl.datastructures.php
  5. Big-O O(1) - Constant no matter how big your data

    O(log n) - Grows slowly with your data O(n) - Grows linearly with your data O(n2) - Grows quadratically with your data O(2n) - Grows exponentially with your data O(n!) - LOL https://en.wikipedia.org/wiki/Big_O
  6. Photo By: Cmglee

  7. Performance SPL version versus simple array 1,000,000 random elements Sorting,

    iterating, or both Time and memory usage
  8. Data Structures SplDoublyLinkedList SplStack SplQueue SplPriorityQueue SplFixedArray SplObjectStorage SplHeap SplMaxHeap

    SplMinHeap
  9. Image By: Bhavikp19

  10. SplDoublyLinkedList Access: O(n) Search: O(n) Insert: O(1) Delete: O(1)

  11. $list = new SplDoublyLinkedList(); $list->push('Ash'); $list->push('Bingo'); $list->push('Charlie'); $list->push('Echo'); foreach ($list

    as $key => $character) { echo $key, ' ', $character, PHP_EOL; } echo PHP_EOL; https://github.com/omnicolor/dark-corners-of-the-spl/blob/master/SplDoublyLinkedList.php
  12. $list->push('Echo'); foreach ($list as $key => $character) { echo $key,

    ' ', $character, PHP_EOL; } echo PHP_EOL; 0 Ash 1 Bingo 2 Charlie 3 Echo
  13. 0 Ash 1 Bingo 2 Charlie 3 Echo $list->add(3, 'Delta');

    foreach ($list as $key => $character) { echo $key, ' ', $character, PHP_EOL; } echo PHP_EOL;
  14. foreach ($list as $key => $character) { echo $key, '

    ', $character, PHP_EOL; } echo PHP_EOL; 0 Ash 1 Bingo 2 Charlie 3 Delta 4 Echo
  15. 2 Charlie 3 Delta 4 Echo $list->rewind(); echo sprintf( "It's

    %s's turn! They take out %s!", $list->current(), $list[2] ), PHP_EOL; $list->offsetUnset(2); foreach ($list as $key => $character) { echo $key, ' ', $character, PHP_EOL; } echo PHP_EOL;
  16. foreach ($list as $key => $character) { echo $key, '

    ', $character, PHP_EOL; } echo PHP_EOL; It's Ash's turn! They take out Charlie! 0 Ash 1 Bingo 2 Delta 3 Echo
  17. Data Structures SplDoublyLinkedList SplStack SplQueue SplPriorityQueue SplFixedArray SplObjectStorage SplHeap SplMaxHeap

    SplMinHeap
  18. SplStack performance $startTime = microtime(true); $startSize = memory_get_usage(); $arrayStack =

    []; for ($i = 0; $i < $numItems; $i++) { array_push($arrayStack, mt_rand()); } $peakSize = memory_get_usage(); while (!empty($arrayStack)) { echo array_pop($arrayStack), ' '; } echo PHP_EOL; $startTime = microtime(true); $startSize = memory_get_usage(); $stack = new SplStack(); for ($i = 0; $i < $numItems; $i++) { $stack->push(mt_rand()); } $peakSize = memory_get_usage(); while (!$stack->isEmpty()) { echo $stack->pop(), ' '; } echo PHP_EOL; https://github.com/omnicolor/dark-corners-of-the-spl/blob/master/SplStackTest.php
  19. SplStack performance Array: 2.78 seconds 32MiB Stack: 2.79 seconds 38MiB

  20. Data Structures SplDoublyLinkedList SplStack SplQueue SplPriorityQueue SplFixedArray SplObjectStorage SplHeap SplMaxHeap

    SplMinHeap
  21. Image By: Ermishin

  22. SplHeap Access: O(log n) Search: O(log n) Insert: O(log n)

    Delete: O(log n)
  23. class Character { public $name; public $initiative; public function __construct(

    string $name, int $init ) { $this->name = $name; $this->initiative = $init; } } https://github.com/omnicolor/dark-corners-of-the-spl/blob/master/SplHeap.php
  24. class InitiativeHeap extends SplMaxHeap { public function compare($a, $b) :

    int { return $a->initiative - $b->initiative; } }
  25. $init = new InitiativeHeap(); $init->insert(new Character('Ash', random_int(1, 30))); $init->insert(new Character('Bingo',

    random_int(1, 30))); $init->insert(new Character('Charlie', random_int(1, 30))); $init->insert(new Character('Echo', random_int(1, 30))); foreach ($init as $character) { echo sprintf( '%s %d', $character->name, $character->initiative ), PHP_EOL; }
  26. foreach ($init as $character) { echo sprintf( '%s %d', $character->name,

    $character->initiative ), PHP_EOL; } Ash 30 Echo 27 Charlie 16 Bingo 12
  27. SplHeap Array: 2.84 seconds 32MiB Heap: 5.20 seconds 16MiB https://github.com/omnicolor/dark-corners-of-the-spl/blob/master/SplHeapTest.php

  28. Data Structures SplDoublyLinkedList SplStack SplQueue SplHeap SplMaxHeap SplMinHeap SplPriorityQueue SplFixedArray

    SplObjectStorage
  29. SplFixedArray Access: O(1) Search: O(n) Insert: O(1) or O(n) Delete:

    O(n)
  30. $a = [ 'foo' => 1, 'bar' => new StdClass(),

    1 => null, false => true, ]; var_dump($a); array(3) { [“foo"]=>int(1) [“bar"]=>object(stdClass)#1 (0) {} [1]=>NULL [0]=>bool(true) } $b = [ 0 => 10, 2 => 22, PHP_INT_MAX => PHP_INT_MAX, ]; var_dump($b); array(3) { [0]=>int(10) [2]=>int(22) [9223372036854775807]=> int(9223372036854775807) } https://github.com/omnicolor/dark-corners-of-the-spl/blob/master/SplFixedArray.php
  31. $c = new SplFixedArray(3); $c[0] = 10; $c[1] = 20;

    $c[2] = 42; var_dump($c); object(SplFixedArray)#2 (3) { [0]=>int(10) [1]=>int(20) [2]=>int(42) }
  32. $d = new SplFixedArray(3); $d[0] = 10; $d[1] = 20;

    $d[2] = 42; $d[3] = 99; var_dump($d); PHP Fatal error: Uncaught RuntimeException: Index invalid or out of range in SplFixedArray.php:33 Stack trace: #0 {main} thrown in SplFixedArray.php on line 33
  33. $e = new SplFixedArray(3); $e[0] = 10; $e[1] = 20;

    $e[2] = 42; $e->setSize(4); $e[3] = 99; var_dump($e); object(SplFixedArray)#5 (4) { [0]=>int(10) [1]=>int(20) [2]=>int(42) [3]=>int(99) }
  34. SplFixedArray Array: 2.58 seconds 32MiB Fixed: 2.67 seconds 15MiB

  35. Data Structures SplDoublyLinkedList SplStack SplQueue SplHeap SplMaxHeap SplMinHeap SplPriorityQueue SplFixedArray

    SplObjectStorage
  36. Data Structures SplDoublyLinkedList SplStack SplQueue SplHeap SplMaxHeap SplMinHeap SplPriorityQueue SplFixedArray

    SplObjectStorage
  37. $char = new Character(); $storage = []; $storage[$char] = [‘alive’

    => true]; Warning: Illegal offset type in SplObjectStorage.php on line 3
  38. class Character {} class Enemy {} class Buff {} class

    Ailment {}
  39. class Buff {} class Ailment {} $fighter = new Character();

    $mage = new Character(); $goblin = new Enemy(); $ogre = new Enemy(); $haste = new Buff(); $poison = new Ailment();
  40. $encounter = new SplObjectStorage(); $encounter->attach($fighter, [$haste]); $encounter->attach($mage, [$haste, $poison]); $encounter[$goblin]

    = [$poison]; $encounter->attach($ogre); foreach ($encounter as $key => $value) { print_r($key); echo PHP_EOL; print_r($value); } $poison = new Ailment();
  41. foreach ($encounter as $key => $value) { print_r($key); echo PHP_EOL;

    print_r($value); } 0 Character Object() 1 Character Object() 2 Enemy Object() 3 Enemy Object()
  42. object(SplObjectStorage)#7 (1) { ["storage":"SplObjectStorage":private]=>array(4) { ["000000005460553e00000000545bda63"]=>array(2) { ["obj"]=>object(Character)#1 (0) {}

    ["inf"]=>array(1) { [0]=>object(Buff)#5 (0) {} } } } }
  43. foreach ($encounter as $key) { print_r($key); print_r($encounter[$key]); }

  44. print_r($encounter[$key]); } Character Object() // fighter Array( [0] => Buff

    Object() // haste ) Character Object() // mage Array( [0] => Buff Object() // haste [1] => Ailment Object() // poison ) Enemy Object() // golbin Array( [0] => Ailment Object() // poison ) Enemy Object()
  45. –Lady Gaga “I just am committed wholeheartedly to theatre with

    no intermission.”
  46. SPL Interfaces Countable OuterIterator RecursiveIterator SeekableIterator SplObserver SplSubject

  47. Countable interface Countable { public function count() : int; }

  48. class Countable { public function count() : int { return

    42; } } $foo = new Countable(); echo count($foo), PHP_EOL;
  49. class Countable { public function count() : int { return

    42; } } $foo = new Countable(); echo count($foo), PHP_EOL; Warning: count(): Parameter must be an array or an object that implements Countable in Countable.php on line 13 1
  50. object that implements Countable in Countable.php on line 13 1

    class ActuallyCountable implements Countable { public function count() { return 42; } } $bar = new ActuallyCountable(); echo count($bar), PHP_EOL;
  51. SplSubject interface SplSubject { function attach(SplObserver $observer): void; function detach(SplObserver

    $observer): void; function notify(): void; }
  52. SplObserver interface SplObserver { function update(SplSubject $subject): void; }

  53. // ... public function attach(\SplObserver $observer): void { $this->observers->attach($observer); }

    class Character implements \SplSubject, \SplObserver { public $name; protected $observers; protected $message; public function __construct(string $name) { $this->name = $name; $this->observers = new \SplObjectStorage(); } // ...
  54. // ... public function update(\SplSubject $subject): void { // ...

    public function attach(\SplObserver $observer): void { $this->observers->attach($observer); } public function detach(\SplObserver $observer): void { $this->observers->detach($observer); } public function notify(): void { foreach ($this->observers as $observer) { $observer->update($this); } } // ... } // ...
  55. // ... public function sendMessage(string $message): void { $this->message =

    $message; $this->notify(); foreach ($this->observers as $observer) { $observer->update($this); } } // ... // ... public function update(\SplSubject $subject): void { echo sprintf( '%s received message: %s', $this->name, $subject->readMessage() ), PHP_EOL; } // ...
  56. $subject->readMessage() ), PHP_EOL; } // ... } $fighter = new

    Character('Fighter'); $mage = new Character('Mage'); $thief = new Character('Thief'); // ... public function sendMessage(string $message): void { $this->message = $message; $this->notify(); } public function readMessage(): string { return sprintf( '%s said "%s"', $this->name, $this->message ); } }
  57. return sprintf( '%s said "%s"', $this->name, $this->message ); } }

    } $fighter = new Character('Fighter'); $mage = new Character('Mage'); $thief = new Character('Thief'); $paladin = new Character('Paladin'); // Fighter, mage, and paladin listen to everyone else. $mage->attach($fighter); $thief->attach($fighter); $paladin->attach($fighter); $fighter->attach($mage); $thief->attach($mage); $paladin->attach($mage); $fighter->attach($paladin); $mage->attach($paladin); $thief->attach($paladin); $thief->attach($paladin);
  58. $thief->attach($paladin); // Thief doesn't pay attention to anyone else, jerk.

    $paladin->sendMessage( ’Get ready for a fight. Mage, can you buff us?’ ); $mage->sendMessage('Sure, give me a second.'); $fighter->sendMessage('LEEEEROY JENKINS!'); $thief->sendMessage('Dangit Fighter!'); $thief->attach($mage); $paladin->attach($mage); $fighter->attach($paladin); $mage->attach($paladin); $thief->attach($paladin);
  59. Fighter received message: Paladin said "Get ready for a fight.

    Mage, can you buff us?" Mage received message: Paladin said "Get ready for a fight. Mage, can you buff us?" Fighter received message: Mage said "Sure, give me a second." Paladin received message: Mage said "Sure, give me a second." Mage received message: Fighter said "LEEEEROY JENKINS!" Paladin received message: Fighter said "LEEEEROY JENKINS!" Fighter received message: Thief said "Dangit Fighter!" Mage received message: Thief said "Dangit Fighter!" Paladin received message: Thief said "Dangit Fighter!"
  60. https://speakerdeck.com/omnicolor/dark-corners-of-the-spl https://twitter.com/omnicolor Omni Adams omni@digitaldarkness.com https://joind.in/talk/46fd8 https://github.com/omnicolor/dark-corners-of-the-spl