C++ standard libraries extensions

Version 1 of the C++ Extensions for Library Fundamentals, ISO/IEC TS 19568:2015 defines the following new components for the C++ standard library:

Not selected for inclusion in C++17

The following components of ISO/IEC TS 19568:2015 were not selected for inclusion in C++17.

Modified versions of existing classes to support type-erased allocators

Defined in header <experimental/functional>
function	a modified version of std::function with support for type-erased allocators (class template)
Defined in header <experimental/future>
promise	a modified version of std::promise with support for type-erased allocators (class template)
packaged_task	a modified version of std::packaged_task with support for type-erased allocators (class template)

Memory resource adaptors

resource_adaptor

adapts an allocator into a memory_resource (alias template)

General utilities

Defined in header <experimental/utility>
erased_type	placeholder type for type erasure, such as in allocators (class)
Defined in header <experimental/type_traits>
invocation_type raw_invocation_type	deduce the implied function type of the callable object when called with the given argument types (class template)

Feature test macros

Defined in header <experimental/optional>
__cpp_lib_experimental_optional	a value of at least 201411 indicates that the optional type is supported (macro constant)
Defined in header <experimental/any>
__cpp_lib_experimental_any	a value of at least 201411 indicates that the any type is supported (macro constant)
Defined in header <experimental/string_view>
__cpp_lib_experimental_string_view	a value of at least 201411 indicates that basic_string_view template is supported (macro constant)
Defined in header <experimental/tuple>
__cpp_lib_experimental_apply	a value of at least 201402 indicates that the tuple apply() function is supported (macro constant)
Defined in header <experimental/type_traits>
__cpp_lib_experimental_type_trait_variable_templates	a value of at least 201402 indicates that variable template type traits are supported (macro constant)
__cpp_lib_experimental_invocation_type	a value of at least 201406 indicates that invocation type traits are supported (macro constant)
Defined in header <experimental/functional>
__cpp_lib_experimental_boyer_moore_searching	a value of at least 201411 indicates that additional searching algorithms are supported (macro constant)
__cpp_lib_experimental_function_erased_allocator	a value of at least 201406 indicates that type-erased allocator for std::function is supported (macro constant)
Defined in header <experimental/future>
__cpp_lib_experimental_promise_erased_allocator	a value of at least 201406 indicates that type-erased allocator for std::promise is supported (macro constant)
__cpp_lib_experimental_packaged_task_erased_allocator	a value of at least 201406 indicates that type-erased allocator for std::packaged_task is supported (macro constant)
Defined in header <experimental/memory>
__cpp_lib_experimental_shared_ptr_arrays	a value of at least 201406 indicates that shared_ptr arrays are supported (macro constant)
Defined in header <experimental/memory_resource>
__cpp_lib_experimental_memory_resources	a value of at least 201402 indicates that polymorphic memory resources are supported (macro constant)
Defined in header <experimental/algorithm>
__cpp_lib_experimental_sample	a value of 201402 indicates that the sample algorithm is supported (macro constant)

Merged into C++17

The following components of ISO/IEC TS 19568:2015 were included into C++17.

optional objects

Defined in header <experimental/optional>
optional	a class template representing optional objects (class template)

class any

Defined in header <experimental/any>
any	a type-safe container for single values of any type (class)

string_view

Defined in header <experimental/string_view>
basic_string_view	a non-owning reference to a string (class template)

Type-erased and polymorphic allocators

Polymorphic allocators and memory resources

The entities in this section are declared in the std::experimental::pmr namespace.

Defined in header <experimental/memory_resource>
memory_resource	an abstract interface for classes that encapsulate memory resources (class)
synchronized_pool_resource	a thread-safe memory_resource for managing allocations in pools of different block sizes (class)
unsynchronized_pool_resource	a thread-unsafe memory_resource for managing allocations in pools of different block sizes (class)
monotonic_buffer_resource	a special-purpose memory_resource that releases the allocated memory only when the resource is destroyed (class)
polymorphic_allocator	an allocator that supports run-time polymorphism based on the memory_resource it is constructed with (class template)
new_delete_resource	returns a static program-wide memory_resource that uses the global operator new and operator delete to allocate and deallocate memory (function)
null_memory_resource	returns a static memory_resource that performs no allocation (function)
get_default_resource	gets the default memory_resource (function)
set_default_resource	sets the default memory_resource (function)

Convenience aliases for containers using polymorphic allocators

Convenience aliases and alias templates for containers using polymorphic allocators are provided in the std::experimental::pmr namespace for the following class templates in the standard library:

Array support for shared_ptr

Defined in header <experimental/memory>
Class	Description
shared_ptr	a modified version of std::shared_ptr that supports arrays (class template)
weak_ptr	a modified version of std::weak_ptr that supports arrays (class template)

Sampling and searching algorithms

Defined in header <experimental/algorithm>
sample	selects n random elements from a sequence (function template)
search	applies a Searcher to a sequence (function template)
Defined in header <experimental/functional>
default_searcher	standard C++ library search algorithm implementation (class template)
make_default_searcher	helper function to create a default_searcher (function template)
boyer_moore_searcher	Boyer-Moore search algorithm implementation (class template)
make_boyer_moore_searcher	helper function to create a boyer_moore_searcher (function template)
boyer_moore_horspool_searcher	Boyer-Moore-Horspool search algorithm implementation (class template)
make_boyer_moore_horspool_searcher	helper function to create a boyer_moore_horspool_searcher (function template)

General utilities

Defined in header <experimental/tuple>
apply	calls a function to a tuple of arguments (function template)

In addition, the TS provides numerous constexpr variable templates for the following type traits and other class templates in the standard library: