README.md



Parallel STL

Parallel STL is an implementation of the C++ standard library algorithms with support for execution policies,
as specified in ISO/IEC 14882:2017 standard, commonly called C++17. The implementation also supports the unsequenced 
execution policy specified in Parallelism TS version 2 and proposed for the next version of the C++ standard in the 
C++ working group paper P1001.
Parallel STL offers efficient support for both parallel and vectorized execution of algorithms. For sequential 
execution, it relies on an available implementation of the C++ standard library.


Prerequisites

To use Parallel STL, you must have the following software installed:


C++ compiler with:


Support for C++11
Support for OpenMP* 4.0 SIMD constructs


Threading Building Blocks (TBB) which is available for download at https://github.com/01org/tbb/


Known issues and limitations


unseq and par_unseq policies only have effect with compilers that support #pragma omp simd or #pragma simd.
Parallel and vector execution is only supported for the algorithms if random access iterators are provided,
while for other iterator types the execution will remain serial.
The following algorithms do not allow efficient SIMD execution: includes, inplace_merge, merge, nth_element,
partial_sort, partial_sort_copy, set_difference, set_intersection, set_symmetric_difference, set_union,
sort, stable_partition, stable_sort, unique.
The initial value type for exclusive_scan, inclusive_scan, transform_exclusive_scan, transform_inclusive_scan
shall be DefaultConstructible. A default constructed-instance of the initial value type shall be the identity element
for the specified binary operation.
For max_element, min_element, minmax_element, partial_sort, partial_sort_copy, sort, stable_sort
the dereferenced value type of the provided iterators shall be DefaultConstructible.
For remove, remove_if, unique the dereferenced value type of the provided iterators shall be MoveConstructible.
The following algorithms require additional O(n) memory space for parallel execution: copy_if, inplace_merge,
partial_sort, partial_sort_copy, partition_copy, remove, remove_if, rotate, sort, stable_sort,
unique, unique_copy.