C++ standard libraries extensions
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                    The C++ Extensions for Library Fundamentals, ISO/IEC TS 19568:xxxx, defines the following new components for the C++ standard library:
| Contents | 
[edit] optional objects
| Defined in header  <experimental/optional> | |
| a class template representing optional objects (class template) | |
[edit]  class any 
| Defined in header  <experimental/any> | |
| a type-safe container for single values of any type (class) | |
[edit]  string_view 
| Defined in header  <experimental/string_view> | |
| a non-owning reference to a string (class template) | |
[edit] Type-erased and polymorphic allocators
[edit] Polymorphic allocators and memory resources
The entities in this section are declared in the std::experimental::pmr namespace.
| Defined in header  <experimental/memory_resource> | |
| an abstract interface for classes that encapsulate memory resources (class) | |
| a thread-safe memory_resource for managing allocations in pools of different block sizes (class) | |
| a thread-unsafe memory_resource for managing allocations in pools of different block sizes (class) | |
| a special-purpose memory_resource that releases the allocated memory only when the resource is destroyed (class) | |
| an allocator that supports run-time polymorphism based on the memory_resource it is constructed with (class template) | |
| adapts an allocator into a memory_resource (alias template) | |
| returns a static program-wide memory_resourcethat uses the global operator new and operator delete to allocate and deallocate memory(function) | |
| returns a static memory_resourcethat performs no allocation(function) | |
| gets the default memory_resource(function) | |
| sets the default memory_resource(function) | |
[edit] Modified versions of existing classes to support type-erased allocators
| Defined in header  <experimental/functional> | |
| a modified version of std::function with support for type-erased allocators (class template) | |
| Defined in header  <experimental/future> | |
| a modified version of std::promise with support for type-erased allocators (class template) | |
| a modified version of std::packaged_task with support for type-erased allocators (class template) | |
[edit] 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:
| List of container templates for which convenience aliases are provided | 
|---|
[edit]
| Defined in header  <experimental/memory> | |
| Class | Description | 
| A modified version of std::shared_ptr that supports arrays (class template) | |
| A modified version of std::weak_ptr that supports arrays (class template) | |
[edit] Sampling and searching algorithms
| Defined in header  <experimental/algorithm> | |
| selects n random elements from a sequence (function template) | |
| applies a Searcher to a sequence (function template) | |
| Defined in header  <experimental/functional> | |
| standard C++ library search algorithm implementation (class template) | |
| helper function to create a default_searcher (function template) | |
| Boyer-Moore search algorithm implementation (class template) | |
| helper function to create a boyer_moore_searcher (function template) | |
| Boyer-Moore-Horspool search algorithm implementation (class template) | |
| helper function to create a boyer_moore_horspool_searcher (function template) | |
[edit] General utilities
| Defined in header  <experimental/utility> | |
| placeholder type for type erasure, such as in allocators (class) | |
| Defined in header  <experimental/tuple> | |
| calls a function to a tuple of arguments (function template) | |
| Defined in header  <experimental/type_traits> | |
| deduce the implied function type of the callable object when called with the given argument types (class template) | |
In addition, the TS provides numerous constexpr variable templates for the following type traits and other class templates in the standard library:
[edit] 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) | 
| Defined in header  <experimental/type_traits> | |
| __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) | 
| Defined in header  <experimental/functional> | |
| __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) | 
| Defined in header  <experimental/future> | |
| __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) | 


