[libcxx] Add <experimental/tuple> header for LFTS.
Summary:
This patch adds the `<experimental/tuple>` header (almost) as specified in the latest draft of the library fundamentals TS.
The main changes in this patch are:
1. Added variable template `tuple_size_v`
2. Added function `apply(Func &&, Tuple &&)`.
3. Changed `__invoke` to be `_LIBCPP_CONSTEXPR_AFTER_CXX11`.
The `apply(...)` implementation uses `__invoke` to invoke the given function. `__invoke` already provides the required functionality. Using `__invoke` also allows `apply` to be used on pointers to member function/objects as an extension. In order to facilitate this `__invoke` has to be marked `constexpr`.
Test Plan:
Each new feature was tested.
The test cases for `tuple_size_v` are as follows:
1. tuple_size_v.pass.cpp
- Check `tuple_size_v` on cv qualified tuples, pairs and arrays.
2. tuple_size_v.fail.cpp
- Test on reference type.
3. tuple_size_v_2.fail.cpp
- Test on non-tuple
4. tuple_size_v_3.fail.cpp
- Test on pointer type.
The test cases for tuple.apply are as follows:
1. arg_type.pass.cpp
- Ensure that ref/pointer/cv qualified types are properly passed.
2. constexpr_types.pass.cpp
- Ensure constexpr evaluation of apply is possible for `tuple` and `pair`.
3. extended_types.pass.cpp
- Test apply on function types permitted by extension.
4. large_arity.pass.cpp
- Test that apply can evaluated on tuples and arrays with large sizes.
5. ref_qualifiers.pass.cpp
- Test that apply respects ref qualified functions.
6. return_type.pass.cpp
- Test that apply returns the proper type.
7. types.pass.cpp
- Test apply on function types as required by LFTS.
Reviewers: mclow.lists
Reviewed By: mclow.lists
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D4512
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@232515 91177308-0d34-0410-b5e6-96231b3b80d8
18 files changed