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528 lines
18 KiB
C++
528 lines
18 KiB
C++
// Copyright 2025 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// -----------------------------------------------------------------------------
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// File: linked_hash_set.h
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// -----------------------------------------------------------------------------
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//
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// This is a simple insertion-ordered set. It provides O(1) amortized
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// insertions and lookups, as well as iteration over the set in the insertion
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// order.
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//
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// This class is thread-compatible.
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//
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// Iterators point into the list and should be stable in the face of
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// mutations, except for an iterator pointing to an element that was just
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// deleted.
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//
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// This class supports heterogeneous lookups.
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#ifndef ABSL_CONTAINER_LINKED_HASH_SET_H_
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#define ABSL_CONTAINER_LINKED_HASH_SET_H_
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#include <cassert>
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#include <cstddef>
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#include <initializer_list>
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#include <list>
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#include <memory>
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#include <type_traits>
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#include <utility>
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#include "absl/base/attributes.h"
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#include "absl/base/config.h"
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#include "absl/container/flat_hash_set.h"
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#include "absl/container/internal/common.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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template <
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typename Key, typename KeyHash = typename absl::flat_hash_set<Key>::hasher,
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typename KeyEq = typename absl::flat_hash_set<Key, KeyHash>::key_equal,
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typename Alloc = std::allocator<Key>>
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class linked_hash_set {
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using KeyArgImpl = absl::container_internal::KeyArg<
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absl::container_internal::IsTransparent<KeyEq>::value &&
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absl::container_internal::IsTransparent<KeyHash>::value>;
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public:
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using key_type = Key;
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using hasher = KeyHash;
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using key_equal = KeyEq;
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using value_type = key_type;
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using allocator_type = Alloc;
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using difference_type = ptrdiff_t;
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private:
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template <class K>
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using key_arg = typename KeyArgImpl::template type<K, key_type>;
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using ListType = std::list<key_type, Alloc>;
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template <class Fn>
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class Wrapped {
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template <typename K>
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static const K& ToKey(const K& k) {
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return k;
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}
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static const key_type& ToKey(typename ListType::const_iterator it) {
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return *it;
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}
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static const key_type& ToKey(typename ListType::iterator it) { return *it; }
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Fn fn_;
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friend linked_hash_set;
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public:
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using is_transparent = void;
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Wrapped() = default;
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explicit Wrapped(Fn fn) : fn_(std::move(fn)) {}
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template <class... Args>
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auto operator()(Args&&... args) const
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-> decltype(this->fn_(ToKey(args)...)) {
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return fn_(ToKey(args)...);
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}
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};
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using SetType =
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absl::flat_hash_set<typename ListType::iterator, Wrapped<hasher>,
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Wrapped<key_equal>, Alloc>;
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class NodeHandle {
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public:
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using allocator_type = linked_hash_set::allocator_type;
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using value_type = linked_hash_set::value_type;
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constexpr NodeHandle() noexcept = default;
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NodeHandle(NodeHandle&& nh) noexcept = default;
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~NodeHandle() = default;
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NodeHandle& operator=(NodeHandle&& node) noexcept = default;
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bool empty() const noexcept { return list_.empty(); }
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explicit operator bool() const noexcept { return !empty(); }
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allocator_type get_allocator() const { return list_.get_allocator(); }
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value_type& value() { return list_.front(); }
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void swap(NodeHandle& nh) noexcept { list_.swap(nh.list_); }
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private:
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friend linked_hash_set;
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explicit NodeHandle(ListType list) : list_(std::move(list)) {}
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ListType list_;
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};
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template <class Iterator, class NodeType>
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struct InsertReturnType {
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Iterator position;
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bool inserted;
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NodeType node;
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};
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public:
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using iterator = typename ListType::const_iterator;
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using const_iterator = typename ListType::const_iterator;
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using reverse_iterator = typename ListType::const_reverse_iterator;
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using const_reverse_iterator = typename ListType::const_reverse_iterator;
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using reference = typename ListType::reference;
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using const_reference = typename ListType::const_reference;
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using pointer = typename std::allocator_traits<allocator_type>::pointer;
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using const_pointer =
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typename std::allocator_traits<allocator_type>::const_pointer;
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using size_type = typename ListType::size_type;
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using node_type = NodeHandle;
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using insert_return_type = InsertReturnType<iterator, node_type>;
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linked_hash_set() {}
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explicit linked_hash_set(size_t bucket_count, const hasher& hash = hasher(),
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const key_equal& eq = key_equal(),
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const allocator_type& alloc = allocator_type())
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: set_(bucket_count, Wrapped<hasher>(hash), Wrapped<key_equal>(eq),
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alloc),
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list_(alloc) {}
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linked_hash_set(size_t bucket_count, const hasher& hash,
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const allocator_type& alloc)
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: linked_hash_set(bucket_count, hash, key_equal(), alloc) {}
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linked_hash_set(size_t bucket_count, const allocator_type& alloc)
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: linked_hash_set(bucket_count, hasher(), key_equal(), alloc) {}
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explicit linked_hash_set(const allocator_type& alloc)
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: linked_hash_set(0, hasher(), key_equal(), alloc) {}
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template <class InputIt>
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linked_hash_set(InputIt first, InputIt last, size_t bucket_count = 0,
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const hasher& hash = hasher(),
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const key_equal& eq = key_equal(),
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const allocator_type& alloc = allocator_type())
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: linked_hash_set(bucket_count, hash, eq, alloc) {
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insert(first, last);
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}
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template <class InputIter>
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linked_hash_set(InputIter first, InputIter last, size_t bucket_count,
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const hasher& hash, const allocator_type& alloc)
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: linked_hash_set(first, last, bucket_count, hash, key_equal(), alloc) {}
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template <class InputIter>
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linked_hash_set(InputIter first, InputIter last, size_t bucket_count,
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const allocator_type& alloc)
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: linked_hash_set(first, last, bucket_count, hasher(), key_equal(),
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alloc) {}
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template <class InputIt>
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linked_hash_set(InputIt first, InputIt last, const allocator_type& alloc)
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: linked_hash_set(first, last, /*bucket_count=*/0, hasher(), key_equal(),
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alloc) {}
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linked_hash_set(std::initializer_list<key_type> init, size_t bucket_count = 0,
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const hasher& hash = hasher(),
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const key_equal& eq = key_equal(),
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const allocator_type& alloc = allocator_type())
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: linked_hash_set(init.begin(), init.end(), bucket_count, hash, eq,
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alloc) {}
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linked_hash_set(std::initializer_list<key_type> init, size_t bucket_count,
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const allocator_type& alloc)
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: linked_hash_set(init, bucket_count, hasher(), key_equal(), alloc) {}
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linked_hash_set(std::initializer_list<key_type> init, size_t bucket_count,
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const hasher& hash, const allocator_type& alloc)
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: linked_hash_set(init, bucket_count, hash, key_equal(), alloc) {}
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linked_hash_set(std::initializer_list<key_type> init,
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const allocator_type& alloc)
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: linked_hash_set(init, /*bucket_count=*/0, hasher(), key_equal(),
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alloc) {}
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linked_hash_set(const linked_hash_set& other)
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: linked_hash_set(other.bucket_count(), other.hash_function(),
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other.key_eq(), other.get_allocator()) {
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CopyFrom(other);
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}
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linked_hash_set(const linked_hash_set& other, const allocator_type& alloc)
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: linked_hash_set(other.bucket_count(), other.hash_function(),
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other.key_eq(), alloc) {
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CopyFrom(other);
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}
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linked_hash_set(linked_hash_set&& other) noexcept
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: set_(std::move(other.set_)), list_(std::move(other.list_)) {
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// Since the list and set must agree for other to end up "valid",
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// explicitly clear them.
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other.set_.clear();
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other.list_.clear();
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}
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linked_hash_set(linked_hash_set&& other, const allocator_type& alloc)
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: linked_hash_set(0, other.hash_function(), other.key_eq(), alloc) {
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if (get_allocator() == other.get_allocator()) {
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*this = std::move(other);
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} else {
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CopyFrom(std::move(other));
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}
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}
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linked_hash_set& operator=(const linked_hash_set& other) {
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if (this != &other) {
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// Make a new set, with other's hash/eq/alloc.
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set_ = SetType(other.bucket_count(), other.set_.hash_function(),
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other.set_.key_eq(), other.get_allocator());
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// Copy the list, with other's allocator.
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list_ = ListType(other.get_allocator());
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CopyFrom(other);
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}
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return *this;
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}
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linked_hash_set& operator=(linked_hash_set&& other) noexcept {
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if (this != &other) {
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set_ = std::move(other.set_);
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list_ = std::move(other.list_);
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other.set_.clear();
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other.list_.clear();
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}
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return *this;
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}
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linked_hash_set& operator=(std::initializer_list<key_type> values) {
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clear();
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insert(values.begin(), values.end());
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return *this;
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}
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// Derive size from set_, as list::size might be O(N).
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size_type size() const { return set_.size(); }
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size_type max_size() const noexcept { return ~size_type{}; }
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bool empty() const { return set_.empty(); }
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// Iteration is list-like, in insertion order.
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// These are all forwarded.
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iterator begin() { return list_.begin(); }
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iterator end() { return list_.end(); }
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const_iterator begin() const { return list_.begin(); }
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const_iterator end() const { return list_.end(); }
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const_iterator cbegin() const { return list_.cbegin(); }
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const_iterator cend() const { return list_.cend(); }
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reverse_iterator rbegin() { return list_.rbegin(); }
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reverse_iterator rend() { return list_.rend(); }
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const_reverse_iterator rbegin() const { return list_.rbegin(); }
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const_reverse_iterator rend() const { return list_.rend(); }
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const_reverse_iterator crbegin() const { return list_.crbegin(); }
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const_reverse_iterator crend() const { return list_.crend(); }
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reference front() { return list_.front(); }
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reference back() { return list_.back(); }
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const_reference front() const { return list_.front(); }
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const_reference back() const { return list_.back(); }
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void pop_front() { erase(begin()); }
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void pop_back() { erase(std::prev(end())); }
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ABSL_ATTRIBUTE_REINITIALIZES void clear() {
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set_.clear();
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list_.clear();
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}
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void reserve(size_t n) { set_.reserve(n); }
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size_t bucket_count() const { return set_.bucket_count(); }
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size_t capacity() const { return set_.capacity(); }
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float load_factor() const { return set_.load_factor(); }
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hasher hash_function() const { return set_.hash_function().fn_; }
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key_equal key_eq() const { return set_.key_eq().fn_; }
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allocator_type get_allocator() const { return list_.get_allocator(); }
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template <typename K = key_type>
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size_type erase(const key_arg<K>& key) {
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auto found = set_.find(key);
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if (found == set_.end()) return 0;
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auto list_it = *found;
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// Erase set entry first since it refers to the list element.
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set_.erase(found);
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list_.erase(list_it);
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return 1;
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}
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iterator erase(const_iterator position) {
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auto found = set_.find(position);
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assert(*found == position);
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set_.erase(found);
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return list_.erase(position);
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}
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iterator erase(const_iterator first, const_iterator last) {
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while (first != last) first = erase(first);
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return first;
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}
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template <typename K = key_type>
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iterator find(const key_arg<K>& key) {
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auto found = set_.find(key);
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if (found == set_.end()) return end();
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return *found;
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}
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template <typename K = key_type>
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const_iterator find(const key_arg<K>& key) const {
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auto found = set_.find(key);
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if (found == set_.end()) return end();
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return *found;
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}
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template <typename K = key_type>
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size_t count(const key_arg<K>& key) const {
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return contains(key) ? 1 : 0;
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}
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template <typename K = key_type>
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bool contains(const key_arg<K>& key) const {
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return set_.contains(key);
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}
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template <typename K = key_type>
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std::pair<iterator, iterator> equal_range(const key_arg<K>& key) {
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auto iter = set_.find(key);
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if (iter == set_.end()) return {end(), end()};
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return {*iter, std::next(*iter)};
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}
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template <typename K = key_type>
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std::pair<const_iterator, const_iterator> equal_range(
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const key_arg<K>& key) const {
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auto iter = set_.find(key);
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if (iter == set_.end()) return {end(), end()};
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return {*iter, std::next(*iter)};
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}
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template <typename K = key_type>
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std::pair<iterator, bool> insert(const key_arg<K>& k) {
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return InsertInternal(list_.end(), k);
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}
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template <typename K = key_type, K* = nullptr>
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std::pair<iterator, bool> insert(key_arg<K>&& k) {
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return InsertInternal(list_.end(), std::move(k));
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}
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template <typename K = key_type,
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std::enable_if_t<
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!std::is_convertible_v<const key_arg<K>&, const_iterator> &&
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!std::is_convertible_v<const key_arg<K>&, iterator>,
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int> = 0>
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iterator insert(const_iterator hint, const key_arg<K>& k) {
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return InsertInternal(hint, k).first;
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}
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template <
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typename K = key_type, K* = nullptr,
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std::enable_if_t<!std::is_convertible_v<key_arg<K>&&, const_iterator> &&
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!std::is_convertible_v<key_arg<K>&&, iterator>,
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int> = 0>
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iterator insert(const_iterator hint, key_arg<K>&& k) {
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return InsertInternal(hint, std::move(k)).first;
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}
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void insert(std::initializer_list<key_type> ilist) {
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insert(ilist.begin(), ilist.end());
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}
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template <class InputIt>
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void insert(InputIt first, InputIt last) {
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for (; first != last; ++first) insert(*first);
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}
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insert_return_type insert(node_type&& node) {
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if (node.empty()) return {end(), false, node_type()};
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if (auto [set_itr, inserted] = set_.emplace(node.list_.begin()); inserted) {
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list_.splice(list_.end(), node.list_);
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return {*set_itr, true, node_type()};
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} else {
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return {*set_itr, false, std::move(node)};
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}
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}
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iterator insert(const_iterator, node_type&& node) {
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return insert(std::move(node)).first;
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}
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template <typename... Args>
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std::pair<iterator, bool> emplace(Args&&... args) {
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return EmplaceInternal(list_.end(), std::forward<Args>(args)...);
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}
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template <typename... Args>
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iterator emplace_hint(const_iterator hint, Args&&... args) {
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return EmplaceInternal(hint, std::forward<Args>(args)...).first;
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}
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template <typename H, typename E>
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void merge(linked_hash_set<Key, H, E, Alloc>& src) {
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auto itr = src.list_.begin();
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while (itr != src.list_.end()) {
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if (contains(*itr)) {
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++itr;
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} else {
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insert(src.extract(itr++));
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}
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}
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}
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template <typename H, typename E>
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void merge(linked_hash_set<Key, H, E, Alloc>&& src) {
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merge(src);
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}
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node_type extract(const_iterator position) {
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set_.erase(position);
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ListType extracted_node_list;
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extracted_node_list.splice(extracted_node_list.end(), list_, position);
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return node_type(std::move(extracted_node_list));
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}
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template <class K = key_type, typename std::enable_if_t<
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!std::is_same<K, iterator>::value, int> = 0>
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node_type extract(const key_arg<K>& key) {
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auto node = set_.extract(key);
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if (node.empty()) return node_type();
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ListType extracted_node_list;
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extracted_node_list.splice(extracted_node_list.end(), list_, node.value());
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return node_type(std::move(extracted_node_list));
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}
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void swap(linked_hash_set& other) noexcept {
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using std::swap;
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swap(set_, other.set_);
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swap(list_, other.list_);
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}
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friend bool operator==(const linked_hash_set& a, const linked_hash_set& b) {
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if (a.size() != b.size()) return false;
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const linked_hash_set* outer = &a;
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const linked_hash_set* inner = &b;
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if (outer->capacity() > inner->capacity()) std::swap(outer, inner);
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for (const value_type& elem : *outer)
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if (!inner->contains(elem)) return false;
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return true;
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}
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friend bool operator!=(const linked_hash_set& a, const linked_hash_set& b) {
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return !(a == b);
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}
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void rehash(size_t n) { set_.rehash(n); }
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private:
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template <typename Other>
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|
void CopyFrom(Other&& other) {
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|
for (auto& elem : other.list_) {
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|
set_.insert(list_.insert(list_.end(), std::move(elem)));
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|
}
|
|
assert(set_.size() == list_.size());
|
|
}
|
|
|
|
template <typename... Args>
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|
std::pair<iterator, bool> EmplaceInternal(const_iterator hint,
|
|
Args&&... args) {
|
|
ListType node_donor;
|
|
auto list_iter =
|
|
node_donor.emplace(node_donor.end(), std::forward<Args>(args)...);
|
|
auto ins = set_.insert(list_iter);
|
|
if (!ins.second) return {*ins.first, false};
|
|
list_.splice(hint, node_donor, list_iter);
|
|
return {list_iter, true};
|
|
}
|
|
|
|
template <typename U>
|
|
std::pair<iterator, bool> InsertInternal(const_iterator hint,
|
|
U&& key) { // NOLINT(build/c++11)
|
|
bool constructed = false;
|
|
auto set_iter = set_.lazy_emplace(key, [&](const auto& ctor) {
|
|
constructed = true;
|
|
ctor(list_.emplace(hint, std::forward<U>(key)));
|
|
});
|
|
return {*set_iter, constructed};
|
|
}
|
|
|
|
// The set component, used for speedy lookups.
|
|
SetType set_;
|
|
|
|
// The list component, used for maintaining insertion order.
|
|
ListType list_;
|
|
};
|
|
|
|
ABSL_NAMESPACE_END
|
|
} // namespace absl
|
|
|
|
#endif // ABSL_CONTAINER_LINKED_HASH_SET_H_
|