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Diffstat (limited to 'absl/container/internal/node_slot_policy.h')
-rw-r--r-- | absl/container/internal/node_slot_policy.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/absl/container/internal/node_slot_policy.h b/absl/container/internal/node_slot_policy.h new file mode 100644 index 00000000..baba5743 --- /dev/null +++ b/absl/container/internal/node_slot_policy.h @@ -0,0 +1,92 @@ +// 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. +// +// Adapts a policy for nodes. +// +// The node policy should model: +// +// struct Policy { +// // Returns a new node allocated and constructed using the allocator, using +// // the specified arguments. +// template <class Alloc, class... Args> +// value_type* new_element(Alloc* alloc, Args&&... args) const; +// +// // Destroys and deallocates node using the allocator. +// template <class Alloc> +// void delete_element(Alloc* alloc, value_type* node) const; +// }; +// +// It may also optionally define `value()` and `apply()`. For documentation on +// these, see hash_policy_traits.h. + +#ifndef ABSL_CONTAINER_INTERNAL_NODE_SLOT_POLICY_H_ +#define ABSL_CONTAINER_INTERNAL_NODE_SLOT_POLICY_H_ + +#include <cassert> +#include <cstddef> +#include <memory> +#include <type_traits> +#include <utility> + +#include "absl/base/config.h" + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace container_internal { + +template <class Reference, class Policy> +struct node_slot_policy { + static_assert(std::is_lvalue_reference<Reference>::value, ""); + + using slot_type = typename std::remove_cv< + typename std::remove_reference<Reference>::type>::type*; + + template <class Alloc, class... Args> + static void construct(Alloc* alloc, slot_type* slot, Args&&... args) { + *slot = Policy::new_element(alloc, std::forward<Args>(args)...); + } + + template <class Alloc> + static void destroy(Alloc* alloc, slot_type* slot) { + Policy::delete_element(alloc, *slot); + } + + template <class Alloc> + static void transfer(Alloc*, slot_type* new_slot, slot_type* old_slot) { + *new_slot = *old_slot; + } + + static size_t space_used(const slot_type* slot) { + if (slot == nullptr) return Policy::element_space_used(nullptr); + return Policy::element_space_used(*slot); + } + + static Reference element(slot_type* slot) { return **slot; } + + template <class T, class P = Policy> + static auto value(T* elem) -> decltype(P::value(elem)) { + return P::value(elem); + } + + template <class... Ts, class P = Policy> + static auto apply(Ts&&... ts) -> decltype(P::apply(std::forward<Ts>(ts)...)) { + return P::apply(std::forward<Ts>(ts)...); + } +}; + +} // namespace container_internal +ABSL_NAMESPACE_END +} // namespace absl + +#endif // ABSL_CONTAINER_INTERNAL_NODE_SLOT_POLICY_H_ |