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/*
* Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
// This implementation is borrowed from Chromium.
#ifndef RTC_BASE_CONTAINERS_FLAT_TREE_H_
#define RTC_BASE_CONTAINERS_FLAT_TREE_H_
#include <algorithm>
#include <iterator>
#include <type_traits>
#include <utility>
#include <vector>
#include "absl/algorithm/container.h"
#include "rtc_base/checks.h"
#include "rtc_base/containers/as_const.h"
#include "rtc_base/containers/not_fn.h"
#include "rtc_base/containers/void_t.h"
#include "rtc_base/system/no_unique_address.h"
namespace webrtc {
// Tag type that allows skipping the sort_and_unique step when constructing a
// flat_tree in case the underlying container is already sorted and has no
// duplicate elements.
struct sorted_unique_t {
constexpr sorted_unique_t() = default;
};
extern sorted_unique_t sorted_unique;
namespace flat_containers_internal {
// Helper functions used in RTC_DCHECKs below to make sure that inputs tagged
// with sorted_unique are indeed sorted and unique.
template <typename Range, typename Comp>
constexpr bool is_sorted_and_unique(const Range& range, Comp comp) {
// Being unique implies that there are no adjacent elements that
// compare equal. So this checks that each element is strictly less
// than the element after it.
return absl::c_adjacent_find(range, webrtc::not_fn(comp)) == std::end(range);
}
// This is a convenience trait inheriting from std::true_type if Iterator is at
// least a ForwardIterator and thus supports multiple passes over a range.
template <class Iterator>
using is_multipass =
std::is_base_of<std::forward_iterator_tag,
typename std::iterator_traits<Iterator>::iterator_category>;
// Uses SFINAE to detect whether type has is_transparent member.
template <typename T, typename = void>
struct IsTransparentCompare : std::false_type {};
template <typename T>
struct IsTransparentCompare<T, void_t<typename T::is_transparent>>
: std::true_type {};
// Helper inspired by C++20's std::to_array to convert a C-style array to a
// std::array. As opposed to the C++20 version this implementation does not
// provide an overload for rvalues and does not strip cv qualifers from the
// returned std::array::value_type. The returned value_type needs to be
// specified explicitly, allowing the construction of std::arrays with const
// elements.
//
// Reference: https://en.cppreference.com/w/cpp/container/array/to_array
template <typename U, typename T, size_t N, size_t... I>
constexpr std::array<U, N> ToArrayImpl(const T (&data)[N],
std::index_sequence<I...>) {
return {{data[I]...}};
}
template <typename U, typename T, size_t N>
constexpr std::array<U, N> ToArray(const T (&data)[N]) {
return ToArrayImpl<U>(data, std::make_index_sequence<N>());
}
// std::pair's operator= is not constexpr prior to C++20. Thus we need this
// small helper to invoke operator= on the .first and .second member explicitly.
template <typename T>
constexpr void Assign(T& lhs, T&& rhs) {
lhs = std::move(rhs);
}
template <typename T, typename U>
constexpr void Assign(std::pair<T, U>& lhs, std::pair<T, U>&& rhs) {
Assign(lhs.first, std::move(rhs.first));
Assign(lhs.second, std::move(rhs.second));
}
// constexpr swap implementation. std::swap is not constexpr prior to C++20.
template <typename T>
constexpr void Swap(T& lhs, T& rhs) {
T tmp = std::move(lhs);
Assign(lhs, std::move(rhs));
Assign(rhs, std::move(tmp));
}
// constexpr prev implementation. std::prev is not constexpr prior to C++17.
template <typename BidirIt>
constexpr BidirIt Prev(BidirIt it) {
return --it;
}
// constexpr next implementation. std::next is not constexpr prior to C++17.
template <typename InputIt>
constexpr InputIt Next(InputIt it) {
return ++it;
}
// constexpr sort implementation. std::sort is not constexpr prior to C++20.
// While insertion sort has a quadratic worst case complexity, it was chosen
// because it has linear complexity for nearly sorted data, is stable, and
// simple to implement.
template <typename BidirIt, typename Compare>
constexpr void InsertionSort(BidirIt first, BidirIt last, const Compare& comp) {
if (first == last)
return;
for (auto it = Next(first); it != last; ++it) {
for (auto curr = it; curr != first && comp(*curr, *Prev(curr)); --curr)
Swap(*curr, *Prev(curr));
}
}
// Implementation -------------------------------------------------------------
// Implementation for the sorted associative flat_set and flat_map using a
// sorted vector as the backing store. Do not use directly.
//
// The use of "value" in this is like std::map uses, meaning it's the thing
// contained (in the case of map it's a <Kay, Mapped> pair). The Key is how
// things are looked up. In the case of a set, Key == Value. In the case of
// a map, the Key is a component of a Value.
//
// The helper class GetKeyFromValue provides the means to extract a key from a
// value for comparison purposes. It should implement:
// const Key& operator()(const Value&).
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
class flat_tree {
public:
// --------------------------------------------------------------------------
// Types.
//
using key_type = Key;
using key_compare = KeyCompare;
using value_type = typename Container::value_type;
// Wraps the templated key comparison to compare values.
struct value_compare {
constexpr bool operator()(const value_type& left,
const value_type& right) const {
GetKeyFromValue extractor;
return comp(extractor(left), extractor(right));
}
RTC_NO_UNIQUE_ADDRESS key_compare comp;
};
using pointer = typename Container::pointer;
using const_pointer = typename Container::const_pointer;
using reference = typename Container::reference;
using const_reference = typename Container::const_reference;
using size_type = typename Container::size_type;
using difference_type = typename Container::difference_type;
using iterator = typename Container::iterator;
using const_iterator = typename Container::const_iterator;
using reverse_iterator = typename Container::reverse_iterator;
using const_reverse_iterator = typename Container::const_reverse_iterator;
using container_type = Container;
// --------------------------------------------------------------------------
// Lifetime.
//
// Constructors that take range guarantee O(N * log^2(N)) + O(N) complexity
// and take O(N * log(N)) + O(N) if extra memory is available (N is a range
// length).
//
// Assume that move constructors invalidate iterators and references.
//
// The constructors that take ranges, lists, and vectors do not require that
// the input be sorted.
//
// When passing the webrtc::sorted_unique tag as the first argument no sort
// and unique step takes places. This is useful if the underlying container
// already has the required properties.
flat_tree() = default;
flat_tree(const flat_tree&) = default;
flat_tree(flat_tree&&) = default;
explicit flat_tree(const key_compare& comp);
template <class InputIterator>
flat_tree(InputIterator first,
InputIterator last,
const key_compare& comp = key_compare());
flat_tree(const container_type& items,
const key_compare& comp = key_compare());
explicit flat_tree(container_type&& items,
const key_compare& comp = key_compare());
flat_tree(std::initializer_list<value_type> ilist,
const key_compare& comp = key_compare());
template <class InputIterator>
flat_tree(sorted_unique_t,
InputIterator first,
InputIterator last,
const key_compare& comp = key_compare());
flat_tree(sorted_unique_t,
const container_type& items,
const key_compare& comp = key_compare());
constexpr flat_tree(sorted_unique_t,
container_type&& items,
const key_compare& comp = key_compare());
flat_tree(sorted_unique_t,
std::initializer_list<value_type> ilist,
const key_compare& comp = key_compare());
~flat_tree() = default;
// --------------------------------------------------------------------------
// Assignments.
//
// Assume that move assignment invalidates iterators and references.
flat_tree& operator=(const flat_tree&) = default;
flat_tree& operator=(flat_tree&&) = default;
// Takes the first if there are duplicates in the initializer list.
flat_tree& operator=(std::initializer_list<value_type> ilist);
// --------------------------------------------------------------------------
// Memory management.
//
// Beware that shrink_to_fit() simply forwards the request to the
// container_type and its implementation is free to optimize otherwise and
// leave capacity() to be greater that its size.
//
// reserve() and shrink_to_fit() invalidate iterators and references.
void reserve(size_type new_capacity);
size_type capacity() const;
void shrink_to_fit();
// --------------------------------------------------------------------------
// Size management.
//
// clear() leaves the capacity() of the flat_tree unchanged.
void clear();
constexpr size_type size() const;
constexpr size_type max_size() const;
constexpr bool empty() const;
// --------------------------------------------------------------------------
// Iterators.
//
// Iterators follow the ordering defined by the key comparator used in
// construction of the flat_tree.
iterator begin();
constexpr const_iterator begin() const;
const_iterator cbegin() const;
iterator end();
constexpr const_iterator end() const;
const_iterator cend() const;
reverse_iterator rbegin();
const_reverse_iterator rbegin() const;
const_reverse_iterator crbegin() const;
reverse_iterator rend();
const_reverse_iterator rend() const;
const_reverse_iterator crend() const;
// --------------------------------------------------------------------------
// Insert operations.
//
// Assume that every operation invalidates iterators and references.
// Insertion of one element can take O(size). Capacity of flat_tree grows in
// an implementation-defined manner.
//
// NOTE: Prefer to build a new flat_tree from a std::vector (or similar)
// instead of calling insert() repeatedly.
std::pair<iterator, bool> insert(const value_type& val);
std::pair<iterator, bool> insert(value_type&& val);
iterator insert(const_iterator position_hint, const value_type& x);
iterator insert(const_iterator position_hint, value_type&& x);
// This method inserts the values from the range [first, last) into the
// current tree.
template <class InputIterator>
void insert(InputIterator first, InputIterator last);
template <class... Args>
std::pair<iterator, bool> emplace(Args&&... args);
template <class... Args>
iterator emplace_hint(const_iterator position_hint, Args&&... args);
// --------------------------------------------------------------------------
// Underlying type operations.
//
// Assume that either operation invalidates iterators and references.
// Extracts the container_type and returns it to the caller. Ensures that
// `this` is `empty()` afterwards.
container_type extract() &&;
// Replaces the container_type with `body`. Expects that `body` is sorted
// and has no repeated elements with regard to value_comp().
void replace(container_type&& body);
// --------------------------------------------------------------------------
// Erase operations.
//
// Assume that every operation invalidates iterators and references.
//
// erase(position), erase(first, last) can take O(size).
// erase(key) may take O(size) + O(log(size)).
//
// Prefer webrtc::EraseIf() or some other variation on erase(remove(), end())
// idiom when deleting multiple non-consecutive elements.
iterator erase(iterator position);
// Artificially templatized to break ambiguity if `iterator` and
// `const_iterator` are the same type.
template <typename DummyT = void>
iterator erase(const_iterator position);
iterator erase(const_iterator first, const_iterator last);
template <typename K>
size_type erase(const K& key);
// --------------------------------------------------------------------------
// Comparators.
constexpr key_compare key_comp() const;
constexpr value_compare value_comp() const;
// --------------------------------------------------------------------------
// Search operations.
//
// Search operations have O(log(size)) complexity.
template <typename K>
size_type count(const K& key) const;
template <typename K>
iterator find(const K& key);
template <typename K>
const_iterator find(const K& key) const;
template <typename K>
bool contains(const K& key) const;
template <typename K>
std::pair<iterator, iterator> equal_range(const K& key);
template <typename K>
std::pair<const_iterator, const_iterator> equal_range(const K& key) const;
template <typename K>
iterator lower_bound(const K& key);
template <typename K>
const_iterator lower_bound(const K& key) const;
template <typename K>
iterator upper_bound(const K& key);
template <typename K>
const_iterator upper_bound(const K& key) const;
// --------------------------------------------------------------------------
// General operations.
//
// Assume that swap invalidates iterators and references.
//
// Implementation note: currently we use operator==() and operator<() on
// std::vector, because they have the same contract we need, so we use them
// directly for brevity and in case it is more optimal than calling equal()
// and lexicograhpical_compare(). If the underlying container type is changed,
// this code may need to be modified.
void swap(flat_tree& other) noexcept;
friend bool operator==(const flat_tree& lhs, const flat_tree& rhs) {
return lhs.body_ == rhs.body_;
}
friend bool operator!=(const flat_tree& lhs, const flat_tree& rhs) {
return !(lhs == rhs);
}
friend bool operator<(const flat_tree& lhs, const flat_tree& rhs) {
return lhs.body_ < rhs.body_;
}
friend bool operator>(const flat_tree& lhs, const flat_tree& rhs) {
return rhs < lhs;
}
friend bool operator>=(const flat_tree& lhs, const flat_tree& rhs) {
return !(lhs < rhs);
}
friend bool operator<=(const flat_tree& lhs, const flat_tree& rhs) {
return !(lhs > rhs);
}
friend void swap(flat_tree& lhs, flat_tree& rhs) noexcept { lhs.swap(rhs); }
protected:
// Emplaces a new item into the tree that is known not to be in it. This
// is for implementing map operator[].
template <class... Args>
iterator unsafe_emplace(const_iterator position, Args&&... args);
// Attempts to emplace a new element with key |key|. Only if |key| is not yet
// present, construct value_type from |args| and insert it. Returns an
// iterator to the element with key |key| and a bool indicating whether an
// insertion happened.
template <class K, class... Args>
std::pair<iterator, bool> emplace_key_args(const K& key, Args&&... args);
// Similar to |emplace_key_args|, but checks |hint| first as a possible
// insertion position.
template <class K, class... Args>
std::pair<iterator, bool> emplace_hint_key_args(const_iterator hint,
const K& key,
Args&&... args);
private:
// Helper class for e.g. lower_bound that can compare a value on the left
// to a key on the right.
struct KeyValueCompare {
// The key comparison object must outlive this class.
explicit KeyValueCompare(const key_compare& comp) : comp_(comp) {}
template <typename T, typename U>
bool operator()(const T& lhs, const U& rhs) const {
return comp_(extract_if_value_type(lhs), extract_if_value_type(rhs));
}
private:
const key_type& extract_if_value_type(const value_type& v) const {
GetKeyFromValue extractor;
return extractor(v);
}
template <typename K>
const K& extract_if_value_type(const K& k) const {
return k;
}
const key_compare& comp_;
};
iterator const_cast_it(const_iterator c_it) {
auto distance = std::distance(cbegin(), c_it);
return std::next(begin(), distance);
}
// This method is inspired by both std::map::insert(P&&) and
// std::map::insert_or_assign(const K&, V&&). It inserts val if an equivalent
// element is not present yet, otherwise it overwrites. It returns an iterator
// to the modified element and a flag indicating whether insertion or
// assignment happened.
template <class V>
std::pair<iterator, bool> insert_or_assign(V&& val) {
auto position = lower_bound(GetKeyFromValue()(val));
if (position == end() || value_comp()(val, *position))
return {body_.emplace(position, std::forward<V>(val)), true};
*position = std::forward<V>(val);
return {position, false};
}
// This method is similar to insert_or_assign, with the following differences:
// - Instead of searching [begin(), end()) it only searches [first, last).
// - In case no equivalent element is found, val is appended to the end of the
// underlying body and an iterator to the next bigger element in [first,
// last) is returned.
template <class V>
std::pair<iterator, bool> append_or_assign(iterator first,
iterator last,
V&& val) {
auto position = std::lower_bound(first, last, val, value_comp());
if (position == last || value_comp()(val, *position)) {
// emplace_back might invalidate position, which is why distance needs to
// be cached.
const difference_type distance = std::distance(begin(), position);
body_.emplace_back(std::forward<V>(val));
return {std::next(begin(), distance), true};
}
*position = std::forward<V>(val);
return {position, false};
}
// This method is similar to insert, with the following differences:
// - Instead of searching [begin(), end()) it only searches [first, last).
// - In case no equivalent element is found, val is appended to the end of the
// underlying body and an iterator to the next bigger element in [first,
// last) is returned.
template <class V>
std::pair<iterator, bool> append_unique(iterator first,
iterator last,
V&& val) {
auto position = std::lower_bound(first, last, val, value_comp());
if (position == last || value_comp()(val, *position)) {
// emplace_back might invalidate position, which is why distance needs to
// be cached.
const difference_type distance = std::distance(begin(), position);
body_.emplace_back(std::forward<V>(val));
return {std::next(begin(), distance), true};
}
return {position, false};
}
void sort_and_unique(iterator first, iterator last) {
// Preserve stability for the unique code below.
std::stable_sort(first, last, value_comp());
// lhs is already <= rhs due to sort, therefore !(lhs < rhs) <=> lhs == rhs.
auto equal_comp = webrtc::not_fn(value_comp());
erase(std::unique(first, last, equal_comp), last);
}
void sort_and_unique() { sort_and_unique(begin(), end()); }
// To support comparators that may not be possible to default-construct, we
// have to store an instance of Compare. Since Compare commonly is stateless,
// we use the RTC_NO_UNIQUE_ADDRESS attribute to save space.
RTC_NO_UNIQUE_ADDRESS key_compare comp_;
// Declare after |key_compare_comp_| to workaround GCC ICE. For details
// see https://crbug.com/1156268
container_type body_;
// If the compare is not transparent we want to construct key_type once.
template <typename K>
using KeyTypeOrK = typename std::
conditional<IsTransparentCompare<key_compare>::value, K, key_type>::type;
};
// ----------------------------------------------------------------------------
// Lifetime.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
const KeyCompare& comp)
: comp_(comp) {}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class InputIterator>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
InputIterator first,
InputIterator last,
const KeyCompare& comp)
: comp_(comp), body_(first, last) {
sort_and_unique();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
const container_type& items,
const KeyCompare& comp)
: comp_(comp), body_(items) {
sort_and_unique();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
container_type&& items,
const KeyCompare& comp)
: comp_(comp), body_(std::move(items)) {
sort_and_unique();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
std::initializer_list<value_type> ilist,
const KeyCompare& comp)
: flat_tree(std::begin(ilist), std::end(ilist), comp) {}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class InputIterator>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
sorted_unique_t,
InputIterator first,
InputIterator last,
const KeyCompare& comp)
: comp_(comp), body_(first, last) {
RTC_DCHECK(is_sorted_and_unique(*this, value_comp()));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
sorted_unique_t,
const container_type& items,
const KeyCompare& comp)
: comp_(comp), body_(items) {
RTC_DCHECK(is_sorted_and_unique(*this, value_comp()));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
sorted_unique_t,
container_type&& items,
const KeyCompare& comp)
: comp_(comp), body_(std::move(items)) {
RTC_DCHECK(is_sorted_and_unique(*this, value_comp()));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::flat_tree(
sorted_unique_t,
std::initializer_list<value_type> ilist,
const KeyCompare& comp)
: flat_tree(sorted_unique, std::begin(ilist), std::end(ilist), comp) {}
// ----------------------------------------------------------------------------
// Assignments.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::operator=(
std::initializer_list<value_type> ilist) -> flat_tree& {
body_ = ilist;
sort_and_unique();
return *this;
}
// ----------------------------------------------------------------------------
// Memory management.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
void flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::reserve(
size_type new_capacity) {
body_.reserve(new_capacity);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::capacity() const
-> size_type {
return body_.capacity();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
void flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::shrink_to_fit() {
body_.shrink_to_fit();
}
// ----------------------------------------------------------------------------
// Size management.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
void flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::clear() {
body_.clear();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::size()
const -> size_type {
return body_.size();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr auto
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::max_size() const
-> size_type {
return body_.max_size();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr bool flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::empty()
const {
return body_.empty();
}
// ----------------------------------------------------------------------------
// Iterators.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::begin()
-> iterator {
return body_.begin();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::begin()
const -> const_iterator {
return std::begin(body_);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::cbegin() const
-> const_iterator {
return body_.cbegin();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::end() -> iterator {
return body_.end();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::end()
const -> const_iterator {
return std::end(body_);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::cend() const
-> const_iterator {
return body_.cend();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::rbegin()
-> reverse_iterator {
return body_.rbegin();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::rbegin() const
-> const_reverse_iterator {
return body_.rbegin();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::crbegin() const
-> const_reverse_iterator {
return body_.crbegin();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::rend()
-> reverse_iterator {
return body_.rend();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::rend() const
-> const_reverse_iterator {
return body_.rend();
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::crend() const
-> const_reverse_iterator {
return body_.crend();
}
// ----------------------------------------------------------------------------
// Insert operations.
//
// Currently we use position_hint the same way as eastl or boost:
// https://github.com/electronicarts/EASTL/blob/master/include/EASTL/vector_set.h#L493
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::insert(
const value_type& val) -> std::pair<iterator, bool> {
return emplace_key_args(GetKeyFromValue()(val), val);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::insert(
value_type&& val) -> std::pair<iterator, bool> {
return emplace_key_args(GetKeyFromValue()(val), std::move(val));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::insert(
const_iterator position_hint,
const value_type& val) -> iterator {
return emplace_hint_key_args(position_hint, GetKeyFromValue()(val), val)
.first;
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::insert(
const_iterator position_hint,
value_type&& val) -> iterator {
return emplace_hint_key_args(position_hint, GetKeyFromValue()(val),
std::move(val))
.first;
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class InputIterator>
void flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::insert(
InputIterator first,
InputIterator last) {
if (first == last)
return;
// Dispatch to single element insert if the input range contains a single
// element.
if (is_multipass<InputIterator>() && std::next(first) == last) {
insert(end(), *first);
return;
}
// Provide a convenience lambda to obtain an iterator pointing past the last
// old element. This needs to be dymanic due to possible re-allocations.
auto middle = [this, size = size()] { return std::next(begin(), size); };
// For batch updates initialize the first insertion point.
difference_type pos_first_new = size();
// Loop over the input range while appending new values and overwriting
// existing ones, if applicable. Keep track of the first insertion point.
for (; first != last; ++first) {
std::pair<iterator, bool> result = append_unique(begin(), middle(), *first);
if (result.second) {
pos_first_new =
std::min(pos_first_new, std::distance(begin(), result.first));
}
}
// The new elements might be unordered and contain duplicates, so post-process
// the just inserted elements and merge them with the rest, inserting them at
// the previously found spot.
sort_and_unique(middle(), end());
std::inplace_merge(std::next(begin(), pos_first_new), middle(), end(),
value_comp());
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class... Args>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::emplace(
Args&&... args) -> std::pair<iterator, bool> {
return insert(value_type(std::forward<Args>(args)...));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class... Args>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::emplace_hint(
const_iterator position_hint,
Args&&... args) -> iterator {
return insert(position_hint, value_type(std::forward<Args>(args)...));
}
// ----------------------------------------------------------------------------
// Underlying type operations.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::
extract() && -> container_type {
return std::exchange(body_, container_type());
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
void flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::replace(
container_type&& body) {
// Ensure that `body` is sorted and has no repeated elements according to
// `value_comp()`.
RTC_DCHECK(is_sorted_and_unique(body, value_comp()));
body_ = std::move(body);
}
// ----------------------------------------------------------------------------
// Erase operations.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::erase(
iterator position) -> iterator {
RTC_CHECK(position != body_.end());
return body_.erase(position);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename DummyT>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::erase(
const_iterator position) -> iterator {
RTC_CHECK(position != body_.end());
return body_.erase(position);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::erase(const K& val)
-> size_type {
auto eq_range = equal_range(val);
auto res = std::distance(eq_range.first, eq_range.second);
erase(eq_range.first, eq_range.second);
return res;
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::erase(
const_iterator first,
const_iterator last) -> iterator {
return body_.erase(first, last);
}
// ----------------------------------------------------------------------------
// Comparators.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr auto
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::key_comp() const
-> key_compare {
return comp_;
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
constexpr auto
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::value_comp() const
-> value_compare {
return value_compare{comp_};
}
// ----------------------------------------------------------------------------
// Search operations.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::count(
const K& key) const -> size_type {
auto eq_range = equal_range(key);
return std::distance(eq_range.first, eq_range.second);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::find(const K& key)
-> iterator {
return const_cast_it(webrtc::as_const(*this).find(key));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::find(
const K& key) const -> const_iterator {
auto eq_range = equal_range(key);
return (eq_range.first == eq_range.second) ? end() : eq_range.first;
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
bool flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::contains(
const K& key) const {
auto lower = lower_bound(key);
return lower != end() && !comp_(key, GetKeyFromValue()(*lower));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::equal_range(
const K& key) -> std::pair<iterator, iterator> {
auto res = webrtc::as_const(*this).equal_range(key);
return {const_cast_it(res.first), const_cast_it(res.second)};
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::equal_range(
const K& key) const -> std::pair<const_iterator, const_iterator> {
auto lower = lower_bound(key);
KeyValueCompare comp(comp_);
if (lower == end() || comp(key, *lower))
return {lower, lower};
return {lower, std::next(lower)};
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::lower_bound(
const K& key) -> iterator {
return const_cast_it(webrtc::as_const(*this).lower_bound(key));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::lower_bound(
const K& key) const -> const_iterator {
static_assert(std::is_convertible<const KeyTypeOrK<K>&, const K&>::value,
"Requested type cannot be bound to the container's key_type "
"which is required for a non-transparent compare.");
const KeyTypeOrK<K>& key_ref = key;
KeyValueCompare comp(comp_);
return absl::c_lower_bound(*this, key_ref, comp);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::upper_bound(
const K& key) -> iterator {
return const_cast_it(webrtc::as_const(*this).upper_bound(key));
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <typename K>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::upper_bound(
const K& key) const -> const_iterator {
static_assert(std::is_convertible<const KeyTypeOrK<K>&, const K&>::value,
"Requested type cannot be bound to the container's key_type "
"which is required for a non-transparent compare.");
const KeyTypeOrK<K>& key_ref = key;
KeyValueCompare comp(comp_);
return absl::c_upper_bound(*this, key_ref, comp);
}
// ----------------------------------------------------------------------------
// General operations.
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
void flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::swap(
flat_tree& other) noexcept {
std::swap(*this, other);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class... Args>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::unsafe_emplace(
const_iterator position,
Args&&... args) -> iterator {
return body_.emplace(position, std::forward<Args>(args)...);
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class K, class... Args>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::emplace_key_args(
const K& key,
Args&&... args) -> std::pair<iterator, bool> {
auto lower = lower_bound(key);
if (lower == end() || comp_(key, GetKeyFromValue()(*lower)))
return {unsafe_emplace(lower, std::forward<Args>(args)...), true};
return {lower, false};
}
template <class Key, class GetKeyFromValue, class KeyCompare, class Container>
template <class K, class... Args>
auto flat_tree<Key, GetKeyFromValue, KeyCompare, Container>::
emplace_hint_key_args(const_iterator hint, const K& key, Args&&... args)
-> std::pair<iterator, bool> {
KeyValueCompare comp(comp_);
if ((hint == begin() || comp(*std::prev(hint), key))) {
if (hint == end() || comp(key, *hint)) {
// *(hint - 1) < key < *hint => key did not exist and hint is correct.
return {unsafe_emplace(hint, std::forward<Args>(args)...), true};
}
if (!comp(*hint, key)) {
// key == *hint => no-op, return correct hint.
return {const_cast_it(hint), false};
}
}
// hint was not helpful, dispatch to hintless version.
return emplace_key_args(key, std::forward<Args>(args)...);
}
// ----------------------------------------------------------------------------
// Free functions.
// Erases all elements that match predicate. It has O(size) complexity.
template <class Key,
class GetKeyFromValue,
class KeyCompare,
class Container,
typename Predicate>
size_t EraseIf(
webrtc::flat_containers_internal::
flat_tree<Key, GetKeyFromValue, KeyCompare, Container>& container,
Predicate pred) {
auto it = std::remove_if(container.begin(), container.end(),
std::forward<Predicate>(pred));
size_t removed = std::distance(it, container.end());
container.erase(it, container.end());
return removed;
}
} // namespace flat_containers_internal
} // namespace webrtc
#endif // RTC_BASE_CONTAINERS_FLAT_TREE_H_