Full description
This repository aims to provide a set of excellent hash map implementations, as well as a btree alternative to std::map and std::set, with the following characteristics:
Header only: nothing to build, just copy the parallel_hashmap directory to your project and you are good to go.
drop-in replacement for std::unordered_map, std::unordered_set, std::map and std::set
Compiler with C++11 support required, C++14 and C++17 APIs are provided (such as try_emplace)
Very efficient, significantly faster than your compiler's unordered map/set or Boost's, or than sparsepp
Memory friendly: low memory usage, although a little higher than sparsepp
Supports heterogeneous lookup
Easy to forward declare: just include phmap_fwd_decl.h in your header files to forward declare Parallel Hashmap containers [note: this does not work currently for hash maps with pointer keys]
Dump/load feature: when a flat hash map stores data that is std::trivially_copyable, the table can be dumped to disk and restored as a single array, very efficiently, and without requiring any hash computation. This is typically about 10 times faster than doing element-wise serialization to disk, but it will use 10% to 60% extra disk space. See examples/serialize.cc. (flat hash map/set only)
Automatic support for boost's hash_value() method for providing the hash function (see examples/hash_value.h). Also default hash support for std::pair and std::tuple.
natvis visualization support in Visual Studio (hash map/set only)
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