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Merge pull request #11092 from DeterminateSystems/hash-SourcePath

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Use std::unordered_map for the EvalState caches
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Eelco Dolstra 2024-07-16 11:06:43 +02:00 • committed by GitHub
commit 9c6678da0e
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4 changed files with 37 additions and 8 deletions
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15
src/libutil/source-path.hh
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@ -9,6 +9,8 @@
#include "canon-path.hh"
#include "source-accessor.hh"
#include <boost/functional/hash.hpp> // for boost::hash_combine
namespace nix {
/**
@ -114,8 +116,21 @@ struct SourcePath
{
return {accessor, accessor->resolveSymlinks(path, mode)};
}
friend class std::hash<nix::SourcePath>;
};
std::ostream & operator << (std::ostream & str, const SourcePath & path);
}
template<>
struct std::hash<nix::SourcePath>
{
std::size_t operator()(const nix::SourcePath & s) const noexcept
{
std::size_t hash = 0;
hash_combine(hash, s.accessor->number, s.path);
return hash;
}
};

14
src/libutil/util.hh
View file

@ -375,4 +375,18 @@ inline std::string operator + (std::string_view s1, const char * s2)
return s;
}
/**
* hash_combine() from Boost. Hash several hashable values together
* into a single hash.
*/
inline void hash_combine(std::size_t & seed) { }
template <typename T, typename... Rest>
inline void hash_combine(std::size_t & seed, const T & v, Rest... rest)
{
std::hash<T> hasher;
seed ^= hasher(v) + 0x9e3779b9 + (seed<<6) + (seed>>2);
hash_combine(seed, rest...);
}
}