diff options
author | Vincent Ambo <mail@tazj.in> | 2022-02-07T23·05+0300 |
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committer | clbot <clbot@tvl.fyi> | 2022-02-07T23·09+0000 |
commit | 5aa5d282eac56a21e74611c1cdbaa97bb5db2dca (patch) | |
tree | 8cc5dce8157a1470ff76719dd15d65f648a05522 /third_party/abseil_cpp/absl/container/internal/hash_function_defaults.h | |
parent | a25675804c4f429fab5ee5201fe25e89865dfd13 (diff) |
chore(3p/abseil_cpp): unvendor abseil_cpp r/3786
we weren't actually using these sources anymore, okay? Change-Id: If701571d9716de308d3512e1eb22c35db0877a66 Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Autosubmit: tazjin <tazjin@tvl.su>
Diffstat (limited to 'third_party/abseil_cpp/absl/container/internal/hash_function_defaults.h')
-rw-r--r-- | third_party/abseil_cpp/absl/container/internal/hash_function_defaults.h | 161 |
1 files changed, 0 insertions, 161 deletions
diff --git a/third_party/abseil_cpp/absl/container/internal/hash_function_defaults.h b/third_party/abseil_cpp/absl/container/internal/hash_function_defaults.h deleted file mode 100644 index 0683422ad89b..000000000000 --- a/third_party/abseil_cpp/absl/container/internal/hash_function_defaults.h +++ /dev/null @@ -1,161 +0,0 @@ -// Copyright 2018 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. -// -// Define the default Hash and Eq functions for SwissTable containers. -// -// std::hash<T> and std::equal_to<T> are not appropriate hash and equal -// functions for SwissTable containers. There are two reasons for this. -// -// SwissTable containers are power of 2 sized containers: -// -// This means they use the lower bits of the hash value to find the slot for -// each entry. The typical hash function for integral types is the identity. -// This is a very weak hash function for SwissTable and any power of 2 sized -// hashtable implementation which will lead to excessive collisions. For -// SwissTable we use murmur3 style mixing to reduce collisions to a minimum. -// -// SwissTable containers support heterogeneous lookup: -// -// In order to make heterogeneous lookup work, hash and equal functions must be -// polymorphic. At the same time they have to satisfy the same requirements the -// C++ standard imposes on hash functions and equality operators. That is: -// -// if hash_default_eq<T>(a, b) returns true for any a and b of type T, then -// hash_default_hash<T>(a) must equal hash_default_hash<T>(b) -// -// For SwissTable containers this requirement is relaxed to allow a and b of -// any and possibly different types. Note that like the standard the hash and -// equal functions are still bound to T. This is important because some type U -// can be hashed by/tested for equality differently depending on T. A notable -// example is `const char*`. `const char*` is treated as a c-style string when -// the hash function is hash<std::string> but as a pointer when the hash -// function is hash<void*>. -// -#ifndef ABSL_CONTAINER_INTERNAL_HASH_FUNCTION_DEFAULTS_H_ -#define ABSL_CONTAINER_INTERNAL_HASH_FUNCTION_DEFAULTS_H_ - -#include <stdint.h> -#include <cstddef> -#include <memory> -#include <string> -#include <type_traits> - -#include "absl/base/config.h" -#include "absl/hash/hash.h" -#include "absl/strings/cord.h" -#include "absl/strings/string_view.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace container_internal { - -// The hash of an object of type T is computed by using absl::Hash. -template <class T, class E = void> -struct HashEq { - using Hash = absl::Hash<T>; - using Eq = std::equal_to<T>; -}; - -struct StringHash { - using is_transparent = void; - - size_t operator()(absl::string_view v) const { - return absl::Hash<absl::string_view>{}(v); - } - size_t operator()(const absl::Cord& v) const { - return absl::Hash<absl::Cord>{}(v); - } -}; - -// Supports heterogeneous lookup for string-like elements. -struct StringHashEq { - using Hash = StringHash; - struct Eq { - using is_transparent = void; - bool operator()(absl::string_view lhs, absl::string_view rhs) const { - return lhs == rhs; - } - bool operator()(const absl::Cord& lhs, const absl::Cord& rhs) const { - return lhs == rhs; - } - bool operator()(const absl::Cord& lhs, absl::string_view rhs) const { - return lhs == rhs; - } - bool operator()(absl::string_view lhs, const absl::Cord& rhs) const { - return lhs == rhs; - } - }; -}; - -template <> -struct HashEq<std::string> : StringHashEq {}; -template <> -struct HashEq<absl::string_view> : StringHashEq {}; -template <> -struct HashEq<absl::Cord> : StringHashEq {}; - -// Supports heterogeneous lookup for pointers and smart pointers. -template <class T> -struct HashEq<T*> { - struct Hash { - using is_transparent = void; - template <class U> - size_t operator()(const U& ptr) const { - return absl::Hash<const T*>{}(HashEq::ToPtr(ptr)); - } - }; - struct Eq { - using is_transparent = void; - template <class A, class B> - bool operator()(const A& a, const B& b) const { - return HashEq::ToPtr(a) == HashEq::ToPtr(b); - } - }; - - private: - static const T* ToPtr(const T* ptr) { return ptr; } - template <class U, class D> - static const T* ToPtr(const std::unique_ptr<U, D>& ptr) { - return ptr.get(); - } - template <class U> - static const T* ToPtr(const std::shared_ptr<U>& ptr) { - return ptr.get(); - } -}; - -template <class T, class D> -struct HashEq<std::unique_ptr<T, D>> : HashEq<T*> {}; -template <class T> -struct HashEq<std::shared_ptr<T>> : HashEq<T*> {}; - -// This header's visibility is restricted. If you need to access the default -// hasher please use the container's ::hasher alias instead. -// -// Example: typename Hash = typename absl::flat_hash_map<K, V>::hasher -template <class T> -using hash_default_hash = typename container_internal::HashEq<T>::Hash; - -// This header's visibility is restricted. If you need to access the default -// key equal please use the container's ::key_equal alias instead. -// -// Example: typename Eq = typename absl::flat_hash_map<K, V, Hash>::key_equal -template <class T> -using hash_default_eq = typename container_internal::HashEq<T>::Eq; - -} // namespace container_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_CONTAINER_INTERNAL_HASH_FUNCTION_DEFAULTS_H_ |