Ds

A pair is used by Ds\Map to pair keys with values.

A PriorityQueue is very similar to a Queue. Values are pushed into the queue with an assigned priority, and the value with the highest priority will always be at the front of the queue.

A Queue is a “first in, first out” or “FIFO” collection that only allows access to the value at the front of the queue and iterates in that order, destructively.

A Set is a sequence of unique values. This implementation uses the same hash table as Ds\Map, where values are used as keys and the mapped value is ignored.

A Stack is a “last in, first out” or “LIFO” collection that only allows access to the value at the top of the structure and iterates in that order, destructively.

A Vector is a sequence of values in a contiguous buffer that grows and shrinks automatically. It’s the most efficient sequential structure because a value’s index is a direct mapping to its index in the buffer, and the growth factor isn't bound to a specific multiple or exponent.

Collection is the base interface which covers functionality common to all the data structures in this library. It guarantees that all structures are traversable, countable, and can be converted to json using json_encode().

Hashable is an interface which allows objects to be used as keys. It’s an alternative to spl_object_hash(), which determines an object’s hash based on its handle: this means that two objects that are considered equal by an implicit definition would not treated as equal because they are not the same instance.

A Sequence describes the behaviour of values arranged in a single, linear dimension. Some languages refer to this as a "List". It’s similar to an array that uses incremental integer keys, with the exception of a few characteristics:

• Values will always be indexed as [0, 1, 2, …, size - 1].
• Only allowed to access values by index in the range [0, size - 1].

Use cases:

• Wherever you would use an array as a list (not concerned with keys).
• A more efficient alternative to SplDoublyLinkedList and SplFixedArray.