binutils-gdb/gdbsupport/unordered_set.h
Simon Marchi 8f942ca8a5 gdbsupport: add unordered_dense.h 4.4.0
Add a copy of unordered_dense.h from [1].  This file implements an
efficient hash map and hash set with a nice C++ interface (a near
drop-in for std::unordered_map and std::unordered_set).  This is
expected to be used to replace uses of `htab_t`, for improved code
readability and type safety.  Performance-wise, it is preferred to the
std types (std::unordered_map and std::unordered_set) due to it using
open addressing vs closed addressing for the std types.

I chose this particular implementation because it is simple to use, it's
a standalone header and it typically performs well in benchmarks I have
seen (e.g. [2]).  The license being MIT, my understanding is that it's
not a problem to use it and re-distribute it.

Add two additional files, gdbsupport/unordered_map.h and
gdbsupport/unordered_set.h, which make the map and set offered by
gdbsupport/unordered_dense.h available as gdb::unordered_map and
gdb::unordered_set.

[1] https://github.com/martinus/unordered_dense
[2] https://jacksonallan.github.io/c_cpp_hash_tables_benchmark/#conclusion-which-hash-table-to-choose

Change-Id: I0c7469ccf9a14540465479e58b2a5140a2440a7d
Approved-By: Tom Tromey <tom@tromey.com>
2024-11-25 22:07:03 -05:00

37 lines
1.2 KiB
C++

/* Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef GDBSUPPORT_UNORDERED_SET_H
#define GDBSUPPORT_UNORDERED_SET_H
#include "unordered_dense.h"
namespace gdb
{
template<typename Key,
typename Hash = ankerl::unordered_dense::hash<Key>,
typename KeyEqual = std::equal_to<Key>>
using unordered_set
= ankerl::unordered_dense::set
<Key, Hash, KeyEqual, std::allocator<Key>,
ankerl::unordered_dense::bucket_type::standard>;
} /* namespace gdb */
#endif /* GDBSUPPORT_UNORDERED_SET_H */