.. _cpp-allocator/allocator:

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allocator.hpp
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Full path: allocator/allocator.hpp

.. default-domain:: cpp
.. default-role:: cpp:expr

.. cpp:namespace:: perm_group

.. concept:: template<typename Alloc> Allocator

    Requires `CopyConstructible<Alloc>`.

    .. assoc_types::

    .. type:: perm = typename Alloc::perm

        The type of permutations that `Alloc` allocates.

        Requires `Permutation<perm>`.

    .. type:: pointer = typename Alloc::pointer
              const_pointer = typename Alloc::const_pointer

        Pointer-like types returned and accepted by the allocator.

        Requires `NullablePointer<pointer>`, `NullablePointer<const_pointer>`.

    .. notation::

    .. var:: Alloc alloc
             const Alloc cAlloc
    .. var:: pointer ptr
             const_pointer cPtr
    .. var:: const UPerm cp

        A `Permutation`.

    .. valid_expr::

    - `*ptr`, type `perm&`.
    - `*cPtr`, type `const perm&`.
    - `cAlloc.degree()`, convertible to an integer type,
      returning the degree of permutations allocated by the allocator.
    - `alloc.make()`, returning a `pointer` to a new permutation.
      Its value is unspecified, and may not be safe to read.
    - `alloc.make_identity()`, returning a `pointer` to a new permutation
      initialized to be the identity permutation.
    - `alloc.copy(cp)`, returning a `pointer` to a new permutation
      initialized to be a copy of the given permutation.
    - `alloc.release(cPtr)`, gives a permutation back to the allocator.
      Permutations must be released by the same allocator or a copy of the allocator
      they were allocated by.