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