1================ 2PSTL integration 3================ 4 5The PSTL (or Parallel STL) project is quite complex in its current form and does not provide everything that libc++ 6requires, for example ``_LIBCPP_HIDE_FROM_ABI`` or similar annotations and including granularized headers. Furthermore, 7the PSTL provides various layers of indirection that make sense in a generic implementation of the parallel algorithms, 8but are unnecessarily complex in the context of a single standard library implementation. Because of these drawbacks, we 9decided to adopt a modified PSTL in libc++. Specifically, the goals of the modified PSTL are 10 11- No ``<__pstl_algorithm>`` and similar glue headers -- instead, the implementation files are included directly in 12 ``<algorithm>`` and friends. 13- No ``<pstl/internal/algorithm_impl.h>`` and ``<pstl/internal/algorithm_fwd.h>`` headers and friends -- these contain 14 the implementation and forward declarations for internal functions respectively. The implementation lives inside 15 ``<__algorithm/pstl_any_of.h>`` and friends, and the forward declarations are not needed inside libc++. 16- No ``<pstl/internal/glue_algorithm_defs.h>`` and ``<pstl/internal/glue_algorithm_impl.h>`` headers and friends -- 17 these contain the public API. It lives inside ``<__algorithm/pstl_any_of.h>`` and friends instead. 18- The headers implementing backends are kept with as few changes as possible to make it easier to keep the backends in 19 sync with the backends from the original PSTL. 20- The configuration headers ``__pstl_config_site.in`` and ``pstl_config.h`` are removed, and any required configuration 21 is done inside ``__config_site.in`` and ``__config`` respectively. 22- libc++-style tests for the public PSTL API 23