diff options
Diffstat (limited to 'third_party/abseil_cpp/absl/container/internal/btree.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/container/internal/btree.h | 651 |
1 files changed, 319 insertions, 332 deletions
diff --git a/third_party/abseil_cpp/absl/container/internal/btree.h b/third_party/abseil_cpp/absl/container/internal/btree.h index f52fe235a2a6..f2fc31df8d41 100644 --- a/third_party/abseil_cpp/absl/container/internal/btree.h +++ b/third_party/abseil_cpp/absl/container/internal/btree.h @@ -137,15 +137,14 @@ struct StringBtreeDefaultGreater { }; // A helper class to convert a boolean comparison into a three-way "compare-to" -// comparison that returns a negative value to indicate less-than, zero to -// indicate equality and a positive value to indicate greater-than. This helper +// comparison that returns an `absl::weak_ordering`. This helper // class is specialized for less<std::string>, greater<std::string>, // less<string_view>, greater<string_view>, less<absl::Cord>, and // greater<absl::Cord>. // // key_compare_to_adapter is provided so that btree users // automatically get the more efficient compare-to code when using common -// google string types with common comparison functors. +// Abseil string types with common comparison functors. // These string-like specializations also turn on heterogeneous lookup by // default. template <typename Compare> @@ -183,12 +182,47 @@ struct key_compare_to_adapter<std::greater<absl::Cord>> { using type = StringBtreeDefaultGreater; }; +// Detects an 'absl_btree_prefer_linear_node_search' member. This is +// a protocol used as an opt-in or opt-out of linear search. +// +// For example, this would be useful for key types that wrap an integer +// and define their own cheap operator<(). For example: +// +// class K { +// public: +// using absl_btree_prefer_linear_node_search = std::true_type; +// ... +// private: +// friend bool operator<(K a, K b) { return a.k_ < b.k_; } +// int k_; +// }; +// +// btree_map<K, V> m; // Uses linear search +// +// If T has the preference tag, then it has a preference. +// Btree will use the tag's truth value. +template <typename T, typename = void> +struct has_linear_node_search_preference : std::false_type {}; +template <typename T, typename = void> +struct prefers_linear_node_search : std::false_type {}; +template <typename T> +struct has_linear_node_search_preference< + T, absl::void_t<typename T::absl_btree_prefer_linear_node_search>> + : std::true_type {}; +template <typename T> +struct prefers_linear_node_search< + T, absl::void_t<typename T::absl_btree_prefer_linear_node_search>> + : T::absl_btree_prefer_linear_node_search {}; + template <typename Key, typename Compare, typename Alloc, int TargetNodeSize, bool Multi, typename SlotPolicy> struct common_params { // If Compare is a common comparator for a string-like type, then we adapt it // to use heterogeneous lookup and to be a key-compare-to comparator. using key_compare = typename key_compare_to_adapter<Compare>::type; + // True when key_compare has been adapted to StringBtreeDefault{Less,Greater}. + using is_key_compare_adapted = + absl::negation<std::is_same<key_compare, Compare>>; // A type which indicates if we have a key-compare-to functor or a plain old // key-compare functor. using is_key_compare_to = btree_is_key_compare_to<key_compare, Key>; @@ -255,10 +289,6 @@ struct common_params { static void move(Alloc *alloc, slot_type *src, slot_type *dest) { slot_policy::move(alloc, src, dest); } - static void move(Alloc *alloc, slot_type *first, slot_type *last, - slot_type *result) { - slot_policy::move(alloc, first, last, result); - } }; // A parameters structure for holding the type parameters for a btree_map. @@ -290,9 +320,17 @@ struct map_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi, }; using is_map_container = std::true_type; - static const Key &key(const value_type &value) { return value.first; } - static const Key &key(const init_type &init) { return init.first; } + template <typename V> + static auto key(const V &value) -> decltype(value.first) { + return value.first; + } static const Key &key(const slot_type *s) { return slot_policy::key(s); } + static const Key &key(slot_type *s) { return slot_policy::key(s); } + // For use in node handle. + static auto mutable_key(slot_type *s) + -> decltype(slot_policy::mutable_key(s)) { + return slot_policy::mutable_key(s); + } static mapped_type &value(value_type *value) { return value->second; } }; @@ -333,13 +371,6 @@ struct set_slot_policy { static void move(Alloc * /*alloc*/, slot_type *src, slot_type *dest) { *dest = std::move(*src); } - - template <typename Alloc> - static void move(Alloc *alloc, slot_type *first, slot_type *last, - slot_type *result) { - for (slot_type *src = first, *dest = result; src != last; ++src, ++dest) - move(alloc, src, dest); - } }; // A parameters structure for holding the type parameters for a btree_set. @@ -353,8 +384,10 @@ struct set_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi, using value_compare = typename set_params::common_params::key_compare; using is_map_container = std::false_type; - static const Key &key(const value_type &value) { return value; } + template <typename V> + static const V &key(const V &value) { return value; } static const Key &key(const slot_type *slot) { return *slot; } + static const Key &key(slot_type *slot) { return *slot; } }; // An adapter class that converts a lower-bound compare into an upper-bound @@ -390,6 +423,10 @@ struct SearchResult { // useful information. template <typename V> struct SearchResult<V, false> { + SearchResult() {} + explicit SearchResult(V value) : value(value) {} + SearchResult(V value, MatchKind /*match*/) : value(value) {} + V value; static constexpr bool HasMatch() { return false; } @@ -420,15 +457,22 @@ class btree_node { using difference_type = typename Params::difference_type; // Btree decides whether to use linear node search as follows: + // - If the comparator expresses a preference, use that. + // - If the key expresses a preference, use that. // - If the key is arithmetic and the comparator is std::less or // std::greater, choose linear. // - Otherwise, choose binary. // TODO(ezb): Might make sense to add condition(s) based on node-size. using use_linear_search = std::integral_constant< bool, - std::is_arithmetic<key_type>::value && - (std::is_same<std::less<key_type>, key_compare>::value || - std::is_same<std::greater<key_type>, key_compare>::value)>; + has_linear_node_search_preference<key_compare>::value + ? prefers_linear_node_search<key_compare>::value + : has_linear_node_search_preference<key_type>::value + ? prefers_linear_node_search<key_type>::value + : std::is_arithmetic<key_type>::value && + (std::is_same<std::less<key_type>, key_compare>::value || + std::is_same<std::greater<key_type>, + key_compare>::value)>; // This class is organized by gtl::Layout as if it had the following // structure: @@ -671,7 +715,7 @@ class btree_node { } ++s; } - return {s}; + return SearchResult<int, false>{s}; } // Returns the position of the first value whose key is not less than k using @@ -706,7 +750,7 @@ class btree_node { e = mid; } } - return {s}; + return SearchResult<int, false>{s}; } // Returns the position of the first value whose key is not less than k using @@ -754,14 +798,10 @@ class btree_node { template <typename... Args> void emplace_value(size_type i, allocator_type *alloc, Args &&... args); - // Removes the value at position i, shifting all existing values and children - // at positions > i to the left by 1. - void remove_value(int i, allocator_type *alloc); - - // Removes the values at positions [i, i + to_erase), shifting all values - // after that range to the left by to_erase. Does not change children at all. - void remove_values_ignore_children(int i, int to_erase, - allocator_type *alloc); + // Removes the values at positions [i, i + to_erase), shifting all existing + // values and children after that range to the left by to_erase. Clears all + // children between [i, i + to_erase). + void remove_values(field_type i, field_type to_erase, allocator_type *alloc); // Rebalances a node with its right sibling. void rebalance_right_to_left(int to_move, btree_node *right, @@ -773,7 +813,7 @@ class btree_node { void split(int insert_position, btree_node *dest, allocator_type *alloc); // Merges a node with its right sibling, moving all of the values and the - // delimiting key in the parent node onto itself. + // delimiting key in the parent node onto itself, and deleting the src node. void merge(btree_node *src, allocator_type *alloc); // Node allocation/deletion routines. @@ -794,35 +834,43 @@ class btree_node { absl::container_internal::SanitizerPoisonMemoryRegion( &mutable_child(start()), (kNodeValues + 1) * sizeof(btree_node *)); } - void destroy(allocator_type *alloc) { - for (int i = start(); i < finish(); ++i) { - value_destroy(i, alloc); - } - } - public: - // Exposed only for tests. - static bool testonly_uses_linear_node_search() { - return use_linear_search::value; + static void deallocate(const size_type size, btree_node *node, + allocator_type *alloc) { + absl::container_internal::Deallocate<Alignment()>(alloc, node, size); } + // Deletes a node and all of its children. + static void clear_and_delete(btree_node *node, allocator_type *alloc); + private: template <typename... Args> - void value_init(const size_type i, allocator_type *alloc, Args &&... args) { + void value_init(const field_type i, allocator_type *alloc, Args &&... args) { absl::container_internal::SanitizerUnpoisonObject(slot(i)); params_type::construct(alloc, slot(i), std::forward<Args>(args)...); } - void value_destroy(const size_type i, allocator_type *alloc) { + void value_destroy(const field_type i, allocator_type *alloc) { params_type::destroy(alloc, slot(i)); absl::container_internal::SanitizerPoisonObject(slot(i)); } + void value_destroy_n(const field_type i, const field_type n, + allocator_type *alloc) { + for (slot_type *s = slot(i), *end = slot(i + n); s != end; ++s) { + params_type::destroy(alloc, s); + absl::container_internal::SanitizerPoisonObject(s); + } + } + + static void transfer(slot_type *dest, slot_type *src, allocator_type *alloc) { + absl::container_internal::SanitizerUnpoisonObject(dest); + params_type::transfer(alloc, dest, src); + absl::container_internal::SanitizerPoisonObject(src); + } // Transfers value from slot `src_i` in `src_node` to slot `dest_i` in `this`. void transfer(const size_type dest_i, const size_type src_i, btree_node *src_node, allocator_type *alloc) { - absl::container_internal::SanitizerUnpoisonObject(slot(dest_i)); - params_type::transfer(alloc, slot(dest_i), src_node->slot(src_i)); - absl::container_internal::SanitizerPoisonObject(src_node->slot(src_i)); + transfer(slot(dest_i), src_node->slot(src_i), alloc); } // Transfers `n` values starting at value `src_i` in `src_node` into the @@ -830,19 +878,11 @@ class btree_node { void transfer_n(const size_type n, const size_type dest_i, const size_type src_i, btree_node *src_node, allocator_type *alloc) { - absl::container_internal::SanitizerUnpoisonMemoryRegion( - slot(dest_i), n * sizeof(slot_type)); for (slot_type *src = src_node->slot(src_i), *end = src + n, *dest = slot(dest_i); src != end; ++src, ++dest) { - params_type::transfer(alloc, dest, src); + transfer(dest, src, alloc); } - // We take care to avoid poisoning transferred-to nodes in case of overlap. - const size_type overlap = - this == src_node ? (std::max)(src_i, dest_i + n) - src_i : 0; - assert(n >= overlap); - absl::container_internal::SanitizerPoisonMemoryRegion( - src_node->slot(src_i + overlap), (n - overlap) * sizeof(slot_type)); } // Same as above, except that we start at the end and work our way to the @@ -850,19 +890,11 @@ class btree_node { void transfer_n_backward(const size_type n, const size_type dest_i, const size_type src_i, btree_node *src_node, allocator_type *alloc) { - absl::container_internal::SanitizerUnpoisonMemoryRegion( - slot(dest_i), n * sizeof(slot_type)); for (slot_type *src = src_node->slot(src_i + n - 1), *end = src - n, *dest = slot(dest_i + n - 1); src != end; --src, --dest) { - params_type::transfer(alloc, dest, src); + transfer(dest, src, alloc); } - // We take care to avoid poisoning transferred-to nodes in case of overlap. - assert(this != src_node || dest_i >= src_i); - const size_type num_to_poison = - this == src_node ? (std::min)(n, dest_i - src_i) : n; - absl::container_internal::SanitizerPoisonMemoryRegion( - src_node->slot(src_i), num_to_poison * sizeof(slot_type)); } template <typename P> @@ -1020,6 +1052,10 @@ template <typename Params> class btree { using node_type = btree_node<Params>; using is_key_compare_to = typename Params::is_key_compare_to; + using init_type = typename Params::init_type; + using field_type = typename node_type::field_type; + using is_multi_container = typename Params::is_multi_container; + using is_key_compare_adapted = typename Params::is_key_compare_adapted; // We use a static empty node for the root/leftmost/rightmost of empty btrees // in order to avoid branching in begin()/end(). @@ -1054,7 +1090,7 @@ class btree { #endif } - enum { + enum : uint32_t { kNodeValues = node_type::kNodeValues, kMinNodeValues = kNodeValues / 2, }; @@ -1106,21 +1142,35 @@ class btree { // before this method is called. This method is used in copy construction, // copy assignment, and move assignment. template <typename Btree> - void copy_or_move_values_in_order(Btree *other); + void copy_or_move_values_in_order(Btree &other); // Validates that various assumptions/requirements are true at compile time. constexpr static bool static_assert_validation(); public: - btree(const key_compare &comp, const allocator_type &alloc); + btree(const key_compare &comp, const allocator_type &alloc) + : root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {} - btree(const btree &other); + btree(const btree &other) : btree(other, other.allocator()) {} + btree(const btree &other, const allocator_type &alloc) + : btree(other.key_comp(), alloc) { + copy_or_move_values_in_order(other); + } btree(btree &&other) noexcept : root_(std::move(other.root_)), rightmost_(absl::exchange(other.rightmost_, EmptyNode())), size_(absl::exchange(other.size_, 0)) { other.mutable_root() = EmptyNode(); } + btree(btree &&other, const allocator_type &alloc) + : btree(other.key_comp(), alloc) { + if (alloc == other.allocator()) { + swap(other); + } else { + // Move values from `other` one at a time when allocators are different. + copy_or_move_values_in_order(other); + } + } ~btree() { // Put static_asserts in destructor to avoid triggering them before the type @@ -1151,11 +1201,11 @@ class btree { // Finds the first element whose key is not less than key. template <typename K> iterator lower_bound(const K &key) { - return internal_end(internal_lower_bound(key)); + return internal_end(internal_lower_bound(key).value); } template <typename K> const_iterator lower_bound(const K &key) const { - return internal_end(internal_lower_bound(key)); + return internal_end(internal_lower_bound(key).value); } // Finds the first element whose key is greater than key. @@ -1169,23 +1219,21 @@ class btree { } // Finds the range of values which compare equal to key. The first member of - // the returned pair is equal to lower_bound(key). The second member pair of - // the pair is equal to upper_bound(key). + // the returned pair is equal to lower_bound(key). The second member of the + // pair is equal to upper_bound(key). template <typename K> - std::pair<iterator, iterator> equal_range(const K &key) { - return {lower_bound(key), upper_bound(key)}; - } + std::pair<iterator, iterator> equal_range(const K &key); template <typename K> std::pair<const_iterator, const_iterator> equal_range(const K &key) const { - return {lower_bound(key), upper_bound(key)}; + return const_cast<btree *>(this)->equal_range(key); } // Inserts a value into the btree only if it does not already exist. The // boolean return value indicates whether insertion succeeded or failed. // Requirement: if `key` already exists in the btree, does not consume `args`. // Requirement: `key` is never referenced after consuming `args`. - template <typename... Args> - std::pair<iterator, bool> insert_unique(const key_type &key, Args &&... args); + template <typename K, typename... Args> + std::pair<iterator, bool> insert_unique(const K &key, Args &&... args); // Inserts with hint. Checks to see if the value should be placed immediately // before `position` in the tree. If so, then the insertion will take @@ -1193,14 +1241,23 @@ class btree { // logarithmic time as if a call to insert_unique() were made. // Requirement: if `key` already exists in the btree, does not consume `args`. // Requirement: `key` is never referenced after consuming `args`. - template <typename... Args> + template <typename K, typename... Args> std::pair<iterator, bool> insert_hint_unique(iterator position, - const key_type &key, + const K &key, Args &&... args); // Insert a range of values into the btree. + // Note: the first overload avoids constructing a value_type if the key + // already exists in the btree. + template <typename InputIterator, + typename = decltype(std::declval<const key_compare &>()( + params_type::key(*std::declval<InputIterator>()), + std::declval<const key_type &>()))> + void insert_iterator_unique(InputIterator b, InputIterator e, int); + // We need the second overload for cases in which we need to construct a + // value_type in order to compare it with the keys already in the btree. template <typename InputIterator> - void insert_iterator_unique(InputIterator b, InputIterator e); + void insert_iterator_unique(InputIterator b, InputIterator e, char); // Inserts a value into the btree. template <typename ValueType> @@ -1233,16 +1290,6 @@ class btree { // to the element after the last erased element. std::pair<size_type, iterator> erase_range(iterator begin, iterator end); - // Erases the specified key from the btree. Returns 1 if an element was - // erased and 0 otherwise. - template <typename K> - size_type erase_unique(const K &key); - - // Erases all of the entries matching the specified key from the - // btree. Returns the number of elements erased. - template <typename K> - size_type erase_multi(const K &key); - // Finds the iterator corresponding to a key or returns end() if the key is // not present. template <typename K> @@ -1254,23 +1301,6 @@ class btree { return internal_end(internal_find(key)); } - // Returns a count of the number of times the key appears in the btree. - template <typename K> - size_type count_unique(const K &key) const { - const iterator begin = internal_find(key); - if (begin.node == nullptr) { - // The key doesn't exist in the tree. - return 0; - } - return 1; - } - // Returns a count of the number of times the key appears in the btree. - template <typename K> - size_type count_multi(const K &key) const { - const auto range = equal_range(key); - return std::distance(range.first, range.second); - } - // Clear the btree, deleting all of the values it contains. void clear(); @@ -1408,25 +1438,8 @@ class btree { } // Deletion helper routines. - void erase_same_node(iterator begin, iterator end); - iterator erase_from_leaf_node(iterator begin, size_type to_erase); iterator rebalance_after_delete(iterator iter); - // Deallocates a node of a certain size in bytes using the allocator. - void deallocate(const size_type size, node_type *node) { - absl::container_internal::Deallocate<node_type::Alignment()>( - mutable_allocator(), node, size); - } - - void delete_internal_node(node_type *node) { - node->destroy(mutable_allocator()); - deallocate(node_type::InternalSize(), node); - } - void delete_leaf_node(node_type *node) { - node->destroy(mutable_allocator()); - deallocate(node_type::LeafSize(node->max_count()), node); - } - // Rebalances or splits the node iter points to. void rebalance_or_split(iterator *iter); @@ -1464,28 +1477,19 @@ class btree { static IterType internal_last(IterType iter); // Returns an iterator pointing to the leaf position at which key would - // reside in the tree. We provide 2 versions of internal_locate. The first - // version uses a less-than comparator and is incapable of distinguishing when - // there is an exact match. The second version is for the key-compare-to - // specialization and distinguishes exact matches. The key-compare-to - // specialization allows the caller to avoid a subsequent comparison to - // determine if an exact match was made, which is important for keys with - // expensive comparison, such as strings. + // reside in the tree, unless there is an exact match - in which case, the + // result may not be on a leaf. When there's a three-way comparator, we can + // return whether there was an exact match. This allows the caller to avoid a + // subsequent comparison to determine if an exact match was made, which is + // important for keys with expensive comparison, such as strings. template <typename K> SearchResult<iterator, is_key_compare_to::value> internal_locate( const K &key) const; - template <typename K> - SearchResult<iterator, false> internal_locate_impl( - const K &key, std::false_type /* IsCompareTo */) const; - - template <typename K> - SearchResult<iterator, true> internal_locate_impl( - const K &key, std::true_type /* IsCompareTo */) const; - // Internal routine which implements lower_bound(). template <typename K> - iterator internal_lower_bound(const K &key) const; + SearchResult<iterator, is_key_compare_to::value> internal_lower_bound( + const K &key) const; // Internal routine which implements upper_bound(). template <typename K> @@ -1495,9 +1499,6 @@ class btree { template <typename K> iterator internal_find(const K &key) const; - // Deletes a node and all of its children. - void internal_clear(node_type *node); - // Verifies the tree structure of node. int internal_verify(const node_type *node, const key_type *lo, const key_type *hi) const; @@ -1517,13 +1518,6 @@ class btree { return res; } - public: - // Exposed only for tests. - static bool testonly_uses_linear_node_search() { - return node_type::testonly_uses_linear_node_search(); - } - - private: // We use compressed tuple in order to save space because key_compare and // allocator_type are usually empty. absl::container_internal::CompressedTuple<key_compare, allocator_type, @@ -1565,26 +1559,27 @@ inline void btree_node<P>::emplace_value(const size_type i, } template <typename P> -inline void btree_node<P>::remove_value(const int i, allocator_type *alloc) { - if (!leaf() && finish() > i + 1) { - assert(child(i + 1)->count() == 0); - for (size_type j = i + 1; j < finish(); ++j) { - set_child(j, child(j + 1)); - } - clear_child(finish()); - } - - remove_values_ignore_children(i, /*to_erase=*/1, alloc); -} +inline void btree_node<P>::remove_values(const field_type i, + const field_type to_erase, + allocator_type *alloc) { + // Transfer values after the removed range into their new places. + value_destroy_n(i, to_erase, alloc); + const field_type orig_finish = finish(); + const field_type src_i = i + to_erase; + transfer_n(orig_finish - src_i, i, src_i, this, alloc); -template <typename P> -inline void btree_node<P>::remove_values_ignore_children( - const int i, const int to_erase, allocator_type *alloc) { - params_type::move(alloc, slot(i + to_erase), finish_slot(), slot(i)); - for (int j = finish() - to_erase; j < finish(); ++j) { - value_destroy(j, alloc); + if (!leaf()) { + // Delete all children between begin and end. + for (int j = 0; j < to_erase; ++j) { + clear_and_delete(child(i + j + 1), alloc); + } + // Rotate children after end into new positions. + for (int j = i + to_erase + 1; j <= orig_finish; ++j) { + set_child(j - to_erase, child(j)); + clear_child(j); + } } - set_finish(finish() - to_erase); + set_finish(orig_finish - to_erase); } template <typename P> @@ -1736,8 +1731,59 @@ void btree_node<P>::merge(btree_node *src, allocator_type *alloc) { set_finish(start() + 1 + count() + src->count()); src->set_finish(src->start()); - // Remove the value on the parent node. - parent()->remove_value(position(), alloc); + // Remove the value on the parent node and delete the src node. + parent()->remove_values(position(), /*to_erase=*/1, alloc); +} + +template <typename P> +void btree_node<P>::clear_and_delete(btree_node *node, allocator_type *alloc) { + if (node->leaf()) { + node->value_destroy_n(node->start(), node->count(), alloc); + deallocate(LeafSize(node->max_count()), node, alloc); + return; + } + if (node->count() == 0) { + deallocate(InternalSize(), node, alloc); + return; + } + + // The parent of the root of the subtree we are deleting. + btree_node *delete_root_parent = node->parent(); + + // Navigate to the leftmost leaf under node, and then delete upwards. + while (!node->leaf()) node = node->start_child(); + // Use `int` because `pos` needs to be able to hold `kNodeValues+1`, which + // isn't guaranteed to be a valid `field_type`. + int pos = node->position(); + btree_node *parent = node->parent(); + for (;;) { + // In each iteration of the next loop, we delete one leaf node and go right. + assert(pos <= parent->finish()); + do { + node = parent->child(pos); + if (!node->leaf()) { + // Navigate to the leftmost leaf under node. + while (!node->leaf()) node = node->start_child(); + pos = node->position(); + parent = node->parent(); + } + node->value_destroy_n(node->start(), node->count(), alloc); + deallocate(LeafSize(node->max_count()), node, alloc); + ++pos; + } while (pos <= parent->finish()); + + // Once we've deleted all children of parent, delete parent and go up/right. + assert(pos > parent->finish()); + do { + node = parent; + pos = node->position(); + parent = node->parent(); + node->value_destroy_n(node->start(), node->count(), alloc); + deallocate(InternalSize(), node, alloc); + if (parent == delete_root_parent) return; + ++pos; + } while (pos > parent->finish()); + } } //// @@ -1794,7 +1840,7 @@ void btree_iterator<N, R, P>::decrement_slow() { // btree methods template <typename P> template <typename Btree> -void btree<P>::copy_or_move_values_in_order(Btree *other) { +void btree<P>::copy_or_move_values_in_order(Btree &other) { static_assert(std::is_same<btree, Btree>::value || std::is_same<const btree, Btree>::value, "Btree type must be same or const."); @@ -1802,11 +1848,11 @@ void btree<P>::copy_or_move_values_in_order(Btree *other) { // We can avoid key comparisons because we know the order of the // values is the same order we'll store them in. - auto iter = other->begin(); - if (iter == other->end()) return; + auto iter = other.begin(); + if (iter == other.end()) return; insert_multi(maybe_move_from_iterator(iter)); ++iter; - for (; iter != other->end(); ++iter) { + for (; iter != other.end(); ++iter) { // If the btree is not empty, we can just insert the new value at the end // of the tree. internal_emplace(end(), maybe_move_from_iterator(iter)); @@ -1845,25 +1891,52 @@ constexpr bool btree<P>::static_assert_validation() { } template <typename P> -btree<P>::btree(const key_compare &comp, const allocator_type &alloc) - : root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {} - -template <typename P> -btree<P>::btree(const btree &other) - : btree(other.key_comp(), other.allocator()) { - copy_or_move_values_in_order(&other); +template <typename K> +auto btree<P>::equal_range(const K &key) -> std::pair<iterator, iterator> { + const SearchResult<iterator, is_key_compare_to::value> res = + internal_lower_bound(key); + const iterator lower = internal_end(res.value); + if (res.HasMatch() ? !res.IsEq() + : lower == end() || compare_keys(key, lower.key())) { + return {lower, lower}; + } + + const iterator next = std::next(lower); + // When the comparator is heterogeneous, we can't assume that comparison with + // non-`key_type` will be equivalent to `key_type` comparisons so there + // could be multiple equivalent keys even in a unique-container. But for + // heterogeneous comparisons from the default string adapted comparators, we + // don't need to worry about this. + if (!is_multi_container::value && + (std::is_same<K, key_type>::value || is_key_compare_adapted::value)) { + // The next iterator after lower must point to a key greater than `key`. + // Note: if this assert fails, then it may indicate that the comparator does + // not meet the equivalence requirements for Compare + // (see https://en.cppreference.com/w/cpp/named_req/Compare). + assert(next == end() || compare_keys(key, next.key())); + return {lower, next}; + } + // Try once more to avoid the call to upper_bound() if there's only one + // equivalent key. This should prevent all calls to upper_bound() in cases of + // unique-containers with heterogeneous comparators in which all comparison + // operators have the same equivalence classes. + if (next == end() || compare_keys(key, next.key())) return {lower, next}; + + // In this case, we need to call upper_bound() to avoid worst case O(N) + // behavior if we were to iterate over equal keys. + return {lower, upper_bound(key)}; } template <typename P> -template <typename... Args> -auto btree<P>::insert_unique(const key_type &key, Args &&... args) +template <typename K, typename... Args> +auto btree<P>::insert_unique(const K &key, Args &&... args) -> std::pair<iterator, bool> { if (empty()) { mutable_root() = rightmost_ = new_leaf_root_node(1); } - auto res = internal_locate(key); - iterator &iter = res.value; + SearchResult<iterator, is_key_compare_to::value> res = internal_locate(key); + iterator iter = res.value; if (res.HasMatch()) { if (res.IsEq()) { @@ -1881,8 +1954,8 @@ auto btree<P>::insert_unique(const key_type &key, Args &&... args) } template <typename P> -template <typename... Args> -inline auto btree<P>::insert_hint_unique(iterator position, const key_type &key, +template <typename K, typename... Args> +inline auto btree<P>::insert_hint_unique(iterator position, const K &key, Args &&... args) -> std::pair<iterator, bool> { if (!empty()) { @@ -1906,14 +1979,23 @@ inline auto btree<P>::insert_hint_unique(iterator position, const key_type &key, } template <typename P> -template <typename InputIterator> -void btree<P>::insert_iterator_unique(InputIterator b, InputIterator e) { +template <typename InputIterator, typename> +void btree<P>::insert_iterator_unique(InputIterator b, InputIterator e, int) { for (; b != e; ++b) { insert_hint_unique(end(), params_type::key(*b), *b); } } template <typename P> +template <typename InputIterator> +void btree<P>::insert_iterator_unique(InputIterator b, InputIterator e, char) { + for (; b != e; ++b) { + init_type value(*b); + insert_hint_unique(end(), params_type::key(value), std::move(value)); + } +} + +template <typename P> template <typename ValueType> auto btree<P>::insert_multi(const key_type &key, ValueType &&v) -> iterator { if (empty()) { @@ -1968,7 +2050,7 @@ auto btree<P>::operator=(const btree &other) -> btree & { *mutable_allocator() = other.allocator(); } - copy_or_move_values_in_order(&other); + copy_or_move_values_in_order(other); } return *this; } @@ -1998,7 +2080,7 @@ auto btree<P>::operator=(btree &&other) noexcept -> btree & { // comparator while moving the values so we can't swap the key // comparators. *mutable_key_comp() = other.key_comp(); - copy_or_move_values_in_order(&other); + copy_or_move_values_in_order(other); } } } @@ -2010,7 +2092,7 @@ auto btree<P>::erase(iterator iter) -> iterator { bool internal_delete = false; if (!iter.node->leaf()) { // Deletion of a value on an internal node. First, move the largest value - // from our left child here, then delete that position (in remove_value() + // from our left child here, then delete that position (in remove_values() // below). We can get to the largest value from our left child by // decrementing iter. iterator internal_iter(iter); @@ -2022,7 +2104,7 @@ auto btree<P>::erase(iterator iter) -> iterator { } // Delete the key from the leaf. - iter.node->remove_value(iter.position, mutable_allocator()); + iter.node->remove_values(iter.position, /*to_erase=*/1, mutable_allocator()); --size_; // We want to return the next value after the one we just erased. If we @@ -2097,7 +2179,9 @@ auto btree<P>::erase_range(iterator begin, iterator end) } if (begin.node == end.node) { - erase_same_node(begin, end); + assert(end.position > begin.position); + begin.node->remove_values(begin.position, end.position - begin.position, + mutable_allocator()); size_ -= count; return {count, rebalance_after_delete(begin)}; } @@ -2107,8 +2191,11 @@ auto btree<P>::erase_range(iterator begin, iterator end) if (begin.node->leaf()) { const size_type remaining_to_erase = size_ - target_size; const size_type remaining_in_node = begin.node->finish() - begin.position; - begin = erase_from_leaf_node( - begin, (std::min)(remaining_to_erase, remaining_in_node)); + const size_type to_erase = + (std::min)(remaining_to_erase, remaining_in_node); + begin.node->remove_values(begin.position, to_erase, mutable_allocator()); + size_ -= to_erase; + begin = rebalance_after_delete(begin); } else { begin = erase(begin); } @@ -2117,79 +2204,9 @@ auto btree<P>::erase_range(iterator begin, iterator end) } template <typename P> -void btree<P>::erase_same_node(iterator begin, iterator end) { - assert(begin.node == end.node); - assert(end.position > begin.position); - - node_type *node = begin.node; - size_type to_erase = end.position - begin.position; - if (!node->leaf()) { - // Delete all children between begin and end. - for (size_type i = 0; i < to_erase; ++i) { - internal_clear(node->child(begin.position + i + 1)); - } - // Rotate children after end into new positions. - for (size_type i = begin.position + to_erase + 1; i <= node->finish(); - ++i) { - node->set_child(i - to_erase, node->child(i)); - node->clear_child(i); - } - } - node->remove_values_ignore_children(begin.position, to_erase, - mutable_allocator()); - - // Do not need to update rightmost_, because - // * either end == this->end(), and therefore node == rightmost_, and still - // exists - // * or end != this->end(), and therefore rightmost_ hasn't been erased, since - // it wasn't covered in [begin, end) -} - -template <typename P> -auto btree<P>::erase_from_leaf_node(iterator begin, size_type to_erase) - -> iterator { - node_type *node = begin.node; - assert(node->leaf()); - assert(node->finish() > begin.position); - assert(begin.position + to_erase <= node->finish()); - - node->remove_values_ignore_children(begin.position, to_erase, - mutable_allocator()); - - size_ -= to_erase; - - return rebalance_after_delete(begin); -} - -template <typename P> -template <typename K> -auto btree<P>::erase_unique(const K &key) -> size_type { - const iterator iter = internal_find(key); - if (iter.node == nullptr) { - // The key doesn't exist in the tree, return nothing done. - return 0; - } - erase(iter); - return 1; -} - -template <typename P> -template <typename K> -auto btree<P>::erase_multi(const K &key) -> size_type { - const iterator begin = internal_lower_bound(key); - if (begin.node == nullptr) { - // The key doesn't exist in the tree, return nothing done. - return 0; - } - // Delete all of the keys between begin and upper_bound(key). - const iterator end = internal_end(internal_upper_bound(key)); - return erase_range(begin, end).first; -} - -template <typename P> void btree<P>::clear() { if (!empty()) { - internal_clear(root()); + node_type::clear_and_delete(root(), mutable_allocator()); } mutable_root() = EmptyNode(); rightmost_ = EmptyNode(); @@ -2244,11 +2261,11 @@ void btree<P>::rebalance_or_split(iterator *iter) { // inserting at the end of the right node then we bias rebalancing to // fill up the left node. int to_move = (kNodeValues - left->count()) / - (1 + (insert_position < kNodeValues)); + (1 + (insert_position < static_cast<int>(kNodeValues))); to_move = (std::max)(1, to_move); if (insert_position - to_move >= node->start() || - left->count() + to_move < kNodeValues) { + left->count() + to_move < static_cast<int>(kNodeValues)) { left->rebalance_right_to_left(to_move, node, mutable_allocator()); assert(node->max_count() - node->count() == to_move); @@ -2272,12 +2289,12 @@ void btree<P>::rebalance_or_split(iterator *iter) { // We bias rebalancing based on the position being inserted. If we're // inserting at the beginning of the left node then we bias rebalancing // to fill up the right node. - int to_move = (kNodeValues - right->count()) / + int to_move = (static_cast<int>(kNodeValues) - right->count()) / (1 + (insert_position > node->start())); to_move = (std::max)(1, to_move); if (insert_position <= node->finish() - to_move || - right->count() + to_move < kNodeValues) { + right->count() + to_move < static_cast<int>(kNodeValues)) { node->rebalance_left_to_right(to_move, right, mutable_allocator()); if (insert_position > node->finish()) { @@ -2330,12 +2347,7 @@ void btree<P>::rebalance_or_split(iterator *iter) { template <typename P> void btree<P>::merge_nodes(node_type *left, node_type *right) { left->merge(right, mutable_allocator()); - if (right->leaf()) { - if (rightmost_ == right) rightmost_ = left; - delete_leaf_node(right); - } else { - delete_internal_node(right); - } + if (rightmost_ == right) rightmost_ = left; } template <typename P> @@ -2345,7 +2357,7 @@ bool btree<P>::try_merge_or_rebalance(iterator *iter) { // Try merging with our left sibling. node_type *left = parent->child(iter->node->position() - 1); assert(left->max_count() == kNodeValues); - if (1 + left->count() + iter->node->count() <= kNodeValues) { + if (1U + left->count() + iter->node->count() <= kNodeValues) { iter->position += 1 + left->count(); merge_nodes(left, iter->node); iter->node = left; @@ -2356,7 +2368,7 @@ bool btree<P>::try_merge_or_rebalance(iterator *iter) { // Try merging with our right sibling. node_type *right = parent->child(iter->node->position() + 1); assert(right->max_count() == kNodeValues); - if (1 + iter->node->count() + right->count() <= kNodeValues) { + if (1U + iter->node->count() + right->count() <= kNodeValues) { merge_nodes(iter->node, right); return true; } @@ -2392,20 +2404,20 @@ bool btree<P>::try_merge_or_rebalance(iterator *iter) { template <typename P> void btree<P>::try_shrink() { - if (root()->count() > 0) { + node_type *orig_root = root(); + if (orig_root->count() > 0) { return; } // Deleted the last item on the root node, shrink the height of the tree. - if (root()->leaf()) { + if (orig_root->leaf()) { assert(size() == 0); - delete_leaf_node(root()); mutable_root() = rightmost_ = EmptyNode(); } else { - node_type *child = root()->start_child(); + node_type *child = orig_root->start_child(); child->make_root(); - delete_internal_node(root()); mutable_root() = child; } + node_type::clear_and_delete(orig_root, mutable_allocator()); } template <typename P> @@ -2433,7 +2445,7 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args) --iter; ++iter.position; } - const int max_count = iter.node->max_count(); + const field_type max_count = iter.node->max_count(); allocator_type *alloc = mutable_allocator(); if (iter.node->count() == max_count) { // Make room in the leaf for the new item. @@ -2450,7 +2462,7 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args) old_root->start(), old_root, alloc); new_root->set_finish(old_root->finish()); old_root->set_finish(old_root->start()); - delete_leaf_node(old_root); + node_type::clear_and_delete(old_root, alloc); mutable_root() = rightmost_ = new_root; } else { rebalance_or_split(&iter); @@ -2465,61 +2477,48 @@ template <typename P> template <typename K> inline auto btree<P>::internal_locate(const K &key) const -> SearchResult<iterator, is_key_compare_to::value> { - return internal_locate_impl(key, is_key_compare_to()); -} - -template <typename P> -template <typename K> -inline auto btree<P>::internal_locate_impl( - const K &key, std::false_type /* IsCompareTo */) const - -> SearchResult<iterator, false> { iterator iter(const_cast<node_type *>(root())); for (;;) { - iter.position = iter.node->lower_bound(key, key_comp()).value; - // NOTE: we don't need to walk all the way down the tree if the keys are - // equal, but determining equality would require doing an extra comparison - // on each node on the way down, and we will need to go all the way to the - // leaf node in the expected case. - if (iter.node->leaf()) { - break; - } - iter.node = iter.node->child(iter.position); - } - return {iter}; -} - -template <typename P> -template <typename K> -inline auto btree<P>::internal_locate_impl( - const K &key, std::true_type /* IsCompareTo */) const - -> SearchResult<iterator, true> { - iterator iter(const_cast<node_type *>(root())); - for (;;) { - SearchResult<int, true> res = iter.node->lower_bound(key, key_comp()); + SearchResult<int, is_key_compare_to::value> res = + iter.node->lower_bound(key, key_comp()); iter.position = res.value; - if (res.match == MatchKind::kEq) { + if (res.IsEq()) { return {iter, MatchKind::kEq}; } + // Note: in the non-key-compare-to case, we don't need to walk all the way + // down the tree if the keys are equal, but determining equality would + // require doing an extra comparison on each node on the way down, and we + // will need to go all the way to the leaf node in the expected case. if (iter.node->leaf()) { break; } iter.node = iter.node->child(iter.position); } + // Note: in the non-key-compare-to case, the key may actually be equivalent + // here (and the MatchKind::kNe is ignored). return {iter, MatchKind::kNe}; } template <typename P> template <typename K> -auto btree<P>::internal_lower_bound(const K &key) const -> iterator { +auto btree<P>::internal_lower_bound(const K &key) const + -> SearchResult<iterator, is_key_compare_to::value> { iterator iter(const_cast<node_type *>(root())); + SearchResult<int, is_key_compare_to::value> res; + bool seen_eq = false; for (;;) { - iter.position = iter.node->lower_bound(key, key_comp()).value; + res = iter.node->lower_bound(key, key_comp()); + iter.position = res.value; + // TODO(ezb): we should be able to terminate early on IsEq() if there can't + // be multiple equivalent keys in container for this lookup type. if (iter.node->leaf()) { break; } + seen_eq = seen_eq || res.IsEq(); iter.node = iter.node->child(iter.position); } - return internal_last(iter); + if (res.IsEq()) return {iter, MatchKind::kEq}; + return {internal_last(iter), seen_eq ? MatchKind::kEq : MatchKind::kNe}; } template <typename P> @@ -2539,7 +2538,7 @@ auto btree<P>::internal_upper_bound(const K &key) const -> iterator { template <typename P> template <typename K> auto btree<P>::internal_find(const K &key) const -> iterator { - auto res = internal_locate(key); + SearchResult<iterator, is_key_compare_to::value> res = internal_locate(key); if (res.HasMatch()) { if (res.IsEq()) { return res.value; @@ -2554,18 +2553,6 @@ auto btree<P>::internal_find(const K &key) const -> iterator { } template <typename P> -void btree<P>::internal_clear(node_type *node) { - if (!node->leaf()) { - for (int i = node->start(); i <= node->finish(); ++i) { - internal_clear(node->child(i)); - } - delete_internal_node(node); - } else { - delete_leaf_node(node); - } -} - -template <typename P> int btree<P>::internal_verify(const node_type *node, const key_type *lo, const key_type *hi) const { assert(node->count() > 0); |