A summary of the namespace.Known big O notationsClassName | 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.
