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    はじめに

    Efficient data structures for PHP 7, provided as an alternative to the array.

    See » this blog post for benchmarks, discussion and frequently asked questions.

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    immemosol
    2 years ago
    A summary of the namespace.

    Known big O notations

    ClassName | add | contains | get | hasKey | insert | pop | push | put | remove | set | shift | unshift |
    Vector | _ | ? | O(1) | _ | O(n) | O(1) | O(1) | _ | O(n) | O(1) | O(n) | O(n) |
    Stack | _ | _ | _ | _ | _ | ? | _ | _ | _ | _ | _ | _ |
    Set | O(1) | O(1) | O(n OR 1) | _ | _ | _ | _ | _ | O(1) | _ | _ | _ |
    Queue | _ | _ | _ | _ | _ | ? | ? | _ | _ | _ | _ | _ |
    PriorityQueue | _ | _ | _ | _ | _ | ? | ? | _ | _ | _ | _ | _ |
    Map | _ | _ | O(1) | O(1) | _ | _ | _ | O(1) | O(1) | _ | _ | _ |
    Deque | _ | ? | O(1) | ? | ? | O(1) | O(1) | _ | ? | O(1) | O(1) | O(1) |

    ? = method is available and big O is unknown.
    _ = method is unavailable, although comparable behavior could be available
    For example: `$object[] = '';` as an alternative to `$object->push('');`.

    Except for PriorityQueue, all other classes
    (Deque, Map, Queue, Set, Stack, Vector) implement ArrayAccess,

    Main:
    - interface Sequence: Collection + ArrayAccess
    - interface Collection: Traversable, Countable, JsonSerializable
    - Vector: Sequential structure, low memory usage
    - Stack: Destructive Iteration; LIFO (Last In, First Out)
    note: can only access the item at the top of the stack
    - Set: Hashable, Unique Values
    - Queue: Destructive Iteration; FIFO (First In, First Out)
    note: can only access the item at the front of the stack
    - PriorityQueue: Destructive Iteration; FIFO + Priority
    Like Queue but priority determines order first, FIFO when equal priority
    - Map: Hashable, Key Value Sequence (like array in comparable context)
    memory usage: like array, clears memory more often
    note: can use objects as keys, but that inhibits array conversion
    - Deque: Double Ended Queue, low memory usage
    note: buffer capacity must be ^2 (a power of 2)

    Supporting:
    - interface Hashable: allows objects to be used as keys (`->hash()` & `->equals()`, falls back to `spl_object_hash()`)
    - class Pair: JsonSerializable, Key Value Pair, used by Map
    - and some more.
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