diff options
Diffstat (limited to 'absl/container/internal/btree.h')
| -rw-r--r-- | absl/container/internal/btree.h | 790 |
1 files changed, 400 insertions, 390 deletions
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h index fd5c0e7a..002ccc1e 100644 --- a/absl/container/internal/btree.h +++ b/absl/container/internal/btree.h @@ -65,6 +65,7 @@ #include "absl/container/internal/layout.h" #include "absl/memory/memory.h" #include "absl/meta/type_traits.h" +#include "absl/strings/cord.h" #include "absl/strings/string_view.h" #include "absl/types/compare.h" #include "absl/utility/utility.h" @@ -93,6 +94,19 @@ struct StringBtreeDefaultLess { absl::string_view rhs) const { return compare_internal::compare_result_as_ordering(lhs.compare(rhs)); } + StringBtreeDefaultLess(std::less<absl::Cord>) {} // NOLINT + absl::weak_ordering operator()(const absl::Cord &lhs, + const absl::Cord &rhs) const { + return compare_internal::compare_result_as_ordering(lhs.Compare(rhs)); + } + absl::weak_ordering operator()(const absl::Cord &lhs, + absl::string_view rhs) const { + return compare_internal::compare_result_as_ordering(lhs.Compare(rhs)); + } + absl::weak_ordering operator()(absl::string_view lhs, + const absl::Cord &rhs) const { + return compare_internal::compare_result_as_ordering(-rhs.Compare(lhs)); + } }; struct StringBtreeDefaultGreater { @@ -107,17 +121,30 @@ struct StringBtreeDefaultGreater { absl::string_view rhs) const { return compare_internal::compare_result_as_ordering(rhs.compare(lhs)); } + StringBtreeDefaultGreater(std::greater<absl::Cord>) {} // NOLINT + absl::weak_ordering operator()(const absl::Cord &lhs, + const absl::Cord &rhs) const { + return compare_internal::compare_result_as_ordering(rhs.Compare(lhs)); + } + absl::weak_ordering operator()(const absl::Cord &lhs, + absl::string_view rhs) const { + return compare_internal::compare_result_as_ordering(-lhs.Compare(rhs)); + } + absl::weak_ordering operator()(absl::string_view lhs, + const absl::Cord &rhs) const { + return compare_internal::compare_result_as_ordering(rhs.Compare(lhs)); + } }; // 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>, and greater<string_view>. +// 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> @@ -145,12 +172,25 @@ struct key_compare_to_adapter<std::greater<absl::string_view>> { using type = StringBtreeDefaultGreater; }; +template <> +struct key_compare_to_adapter<std::less<absl::Cord>> { + using type = StringBtreeDefaultLess; +}; + +template <> +struct key_compare_to_adapter<std::greater<absl::Cord>> { + using type = StringBtreeDefaultGreater; +}; + template <typename Key, typename Compare, typename Alloc, int TargetNodeSize, bool Multi, typename SlotPolicy> struct common_params { - // If Compare is a common comparator for a std::string-like type, then we adapt it + // 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>; @@ -217,10 +257,6 @@ 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. @@ -252,9 +288,17 @@ struct map_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi, }; using is_map_container = std::true_type; - static const Key &key(const value_type &x) { return x.first; } - static const Key &key(const init_type &x) { return x.first; } - static const Key &key(const slot_type *x) { return slot_policy::key(x); } + 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; } }; @@ -295,13 +339,6 @@ 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. @@ -315,8 +352,10 @@ 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 &x) { return x; } - static const Key &key(const slot_type *x) { return *x; } + 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 @@ -326,8 +365,8 @@ struct set_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi, template <typename Compare> struct upper_bound_adapter { explicit upper_bound_adapter(const Compare &c) : comp(c) {} - template <typename K, typename LK> - bool operator()(const K &a, const LK &b) const { + template <typename K1, typename K2> + bool operator()(const K1 &a, const K2 &b) const { // Returns true when a is not greater than b. return !compare_internal::compare_result_as_less_than(comp(b, a)); } @@ -716,14 +755,10 @@ 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, @@ -735,40 +770,36 @@ 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. - void merge(btree_node *sibling, allocator_type *alloc); - - // Swap the contents of "this" and "src". - void swap(btree_node *src, allocator_type *alloc); + // 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. - static btree_node *init_leaf(btree_node *n, btree_node *parent, - int max_count) { - n->set_parent(parent); - n->set_position(0); - n->set_start(0); - n->set_finish(0); - n->set_max_count(max_count); + void init_leaf(btree_node *parent, int max_count) { + set_parent(parent); + set_position(0); + set_start(0); + set_finish(0); + set_max_count(max_count); absl::container_internal::SanitizerPoisonMemoryRegion( - n->start_slot(), max_count * sizeof(slot_type)); - return n; + start_slot(), max_count * sizeof(slot_type)); } - static btree_node *init_internal(btree_node *n, btree_node *parent) { - init_leaf(n, parent, kNodeValues); + void init_internal(btree_node *parent) { + init_leaf(parent, kNodeValues); // Set `max_count` to a sentinel value to indicate that this node is // internal. - n->set_max_count(kInternalNodeMaxCount); + set_max_count(kInternalNodeMaxCount); absl::container_internal::SanitizerPoisonMemoryRegion( - &n->mutable_child(n->start()), - (kNodeValues + 1) * sizeof(btree_node *)); - return n; + &mutable_child(start()), (kNodeValues + 1) * sizeof(btree_node *)); } - void destroy(allocator_type *alloc) { - for (int i = start(); i < finish(); ++i) { - value_destroy(i, alloc); - } + + 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); + public: // Exposed only for tests. static bool testonly_uses_linear_node_search() { @@ -777,33 +808,55 @@ class btree_node { 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) { + transfer(slot(dest_i), src_node->slot(src_i), alloc); + } - // Move n values starting at value i in this node into the values starting at - // value j in node x. - void uninitialized_move_n(const size_type n, const size_type i, - const size_type j, btree_node *x, - allocator_type *alloc) { - absl::container_internal::SanitizerUnpoisonMemoryRegion( - x->slot(j), n * sizeof(slot_type)); - for (slot_type *src = slot(i), *end = src + n, *dest = x->slot(j); + // Transfers `n` values starting at value `src_i` in `src_node` into the + // values starting at value `dest_i` in `this`. + void transfer_n(const size_type n, const size_type dest_i, + const size_type src_i, btree_node *src_node, + allocator_type *alloc) { + for (slot_type *src = src_node->slot(src_i), *end = src + n, + *dest = slot(dest_i); src != end; ++src, ++dest) { - params_type::construct(alloc, dest, src); + transfer(dest, src, alloc); } } - // Destroys a range of n values, starting at index i. - void value_destroy_n(const size_type i, const size_type n, - allocator_type *alloc) { - for (int j = 0; j < n; ++j) { - value_destroy(i + j, alloc); + // Same as above, except that we start at the end and work our way to the + // beginning. + 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) { + for (slot_type *src = src_node->slot(src_i + n - 1), *end = src - n, + *dest = slot(dest_i + n - 1); + src != end; --src, --dest) { + transfer(dest, src, alloc); } } @@ -856,8 +909,8 @@ struct btree_iterator { std::is_same<btree_iterator<N, R, P>, iterator>::value && std::is_same<btree_iterator, const_iterator>::value, int> = 0> - btree_iterator(const btree_iterator<N, R, P> &x) // NOLINT - : node(x.node), position(x.position) {} + btree_iterator(const btree_iterator<N, R, P> &other) // NOLINT + : node(other.node), position(other.position) {} private: // This SFINAE allows explicit conversions from const_iterator to @@ -869,8 +922,8 @@ struct btree_iterator { std::is_same<btree_iterator<N, R, P>, const_iterator>::value && std::is_same<btree_iterator, iterator>::value, int> = 0> - explicit btree_iterator(const btree_iterator<N, R, P> &x) - : node(const_cast<node_type *>(x.node)), position(x.position) {} + explicit btree_iterator(const btree_iterator<N, R, P> &other) + : node(const_cast<node_type *>(other.node)), position(other.position) {} // Increment/decrement the iterator. void increment() { @@ -890,16 +943,27 @@ struct btree_iterator { void decrement_slow(); public: - bool operator==(const const_iterator &x) const { - return node == x.node && position == x.position; + bool operator==(const iterator &other) const { + return node == other.node && position == other.position; + } + bool operator==(const const_iterator &other) const { + return node == other.node && position == other.position; } - bool operator!=(const const_iterator &x) const { - return node != x.node || position != x.position; + bool operator!=(const iterator &other) const { + return node != other.node || position != other.position; + } + bool operator!=(const const_iterator &other) const { + return node != other.node || position != other.position; } // Accessors for the key/value the iterator is pointing at. - reference operator*() const { return node->value(position); } - pointer operator->() const { return &node->value(position); } + reference operator*() const { + ABSL_HARDENING_ASSERT(node != nullptr); + ABSL_HARDENING_ASSERT(node->start() <= position); + ABSL_HARDENING_ASSERT(node->finish() > position); + return node->value(position); + } + pointer operator->() const { return &operator*(); } btree_iterator &operator++() { increment(); @@ -942,7 +1006,8 @@ struct btree_iterator { // The node in the tree the iterator is pointing at. Node *node; // The position within the node of the tree the iterator is pointing at. - // TODO(ezb): make this a field_type + // NOTE: this is an int rather than a field_type because iterators can point + // to invalid positions (such as -1) in certain circumstances. int position; }; @@ -950,6 +1015,10 @@ 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(). @@ -984,7 +1053,7 @@ class btree { #endif } - enum { + enum : uint32_t { kNodeValues = node_type::kNodeValues, kMinNodeValues = kNodeValues / 2, }; @@ -994,9 +1063,9 @@ class btree { node_stats(size_type l, size_type i) : leaf_nodes(l), internal_nodes(i) {} - node_stats &operator+=(const node_stats &x) { - leaf_nodes += x.leaf_nodes; - internal_nodes += x.internal_nodes; + node_stats &operator+=(const node_stats &other) { + leaf_nodes += other.leaf_nodes; + internal_nodes += other.internal_nodes; return *this; } @@ -1028,15 +1097,15 @@ class btree { private: // For use in copy_or_move_values_in_order. - const value_type &maybe_move_from_iterator(const_iterator x) { return *x; } - value_type &&maybe_move_from_iterator(iterator x) { return std::move(*x); } + const value_type &maybe_move_from_iterator(const_iterator it) { return *it; } + value_type &&maybe_move_from_iterator(iterator it) { return std::move(*it); } // Copies or moves (depending on the template parameter) the values in - // x into this btree in their order in x. This btree must be empty before this - // method is called. This method is used in copy construction, copy - // assignment, and move assignment. + // other into this btree in their order in other. This btree must be empty + // 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 *x); + 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(); @@ -1044,12 +1113,12 @@ class btree { public: btree(const key_compare &comp, const allocator_type &alloc); - btree(const btree &x); - btree(btree &&x) noexcept - : root_(std::move(x.root_)), - rightmost_(absl::exchange(x.rightmost_, EmptyNode())), - size_(absl::exchange(x.size_, 0)) { - x.mutable_root() = EmptyNode(); + btree(const btree &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() { @@ -1059,9 +1128,9 @@ class btree { clear(); } - // Assign the contents of x to *this. - btree &operator=(const btree &x); - btree &operator=(btree &&x) noexcept; + // Assign the contents of other to *this. + btree &operator=(const btree &other); + btree &operator=(btree &&other) noexcept; iterator begin() { return iterator(leftmost()); } const_iterator begin() const { return const_iterator(leftmost()); } @@ -1099,23 +1168,21 @@ 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 @@ -1123,14 +1190,23 @@ 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> @@ -1204,15 +1280,15 @@ class btree { // Clear the btree, deleting all of the values it contains. void clear(); - // Swap the contents of *this and x. - void swap(btree &x); + // Swaps the contents of `this` and `other`. + void swap(btree &other); const key_compare &key_comp() const noexcept { return root_.template get<0>(); } - template <typename K, typename LK> - bool compare_keys(const K &x, const LK &y) const { - return compare_internal::compare_result_as_less_than(key_comp()(x, y)); + template <typename K1, typename K2> + bool compare_keys(const K1 &a, const K2 &b) const { + return compare_internal::compare_result_as_less_than(key_comp()(a, b)); } value_compare value_comp() const { return value_compare(key_comp()); } @@ -1322,38 +1398,24 @@ class btree { // Node creation/deletion routines. node_type *new_internal_node(node_type *parent) { - node_type *p = allocate(node_type::InternalSize()); - return node_type::init_internal(p, parent); + node_type *n = allocate(node_type::InternalSize()); + n->init_internal(parent); + return n; } node_type *new_leaf_node(node_type *parent) { - node_type *p = allocate(node_type::LeafSize()); - return node_type::init_leaf(p, parent, kNodeValues); + node_type *n = allocate(node_type::LeafSize()); + n->init_leaf(parent, kNodeValues); + return n; } node_type *new_leaf_root_node(const int max_count) { - node_type *p = allocate(node_type::LeafSize(max_count)); - return node_type::init_leaf(p, p, max_count); + node_type *n = allocate(node_type::LeafSize(max_count)); + n->init_leaf(/*parent=*/n, max_count); + return n; } // 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); @@ -1422,9 +1484,6 @@ 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; @@ -1477,10 +1536,8 @@ inline void btree_node<P>::emplace_value(const size_type i, // Shift old values to create space for new value and then construct it in // place. if (i < finish()) { - value_init(finish(), alloc, slot(finish() - 1)); - for (size_type j = finish() - 1; j > i; --j) - params_type::move(alloc, slot(j - 1), slot(j)); - value_destroy(i, alloc); + transfer_n_backward(finish() - i, /*dest_i=*/i + 1, /*src_i=*/i, this, + alloc); } value_init(i, alloc, std::forward<Args>(args)...); set_finish(finish() + 1); @@ -1494,24 +1551,27 @@ 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)); +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); + + 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); } - clear_child(finish()); } - - remove_values_ignore_children(i, /*to_erase=*/1, 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)); - value_destroy_n(finish() - to_erase, to_erase, alloc); - set_finish(finish() - to_erase); + set_finish(orig_finish - to_erase); } template <typename P> @@ -1525,22 +1585,17 @@ void btree_node<P>::rebalance_right_to_left(const int to_move, assert(to_move <= right->count()); // 1) Move the delimiting value in the parent to the left node. - value_init(finish(), alloc, parent()->slot(position())); + transfer(finish(), position(), parent(), alloc); // 2) Move the (to_move - 1) values from the right node to the left node. - right->uninitialized_move_n(to_move - 1, right->start(), finish() + 1, this, - alloc); + transfer_n(to_move - 1, finish() + 1, right->start(), right, alloc); // 3) Move the new delimiting value to the parent from the right node. - params_type::move(alloc, right->slot(to_move - 1), - parent()->slot(position())); + parent()->transfer(position(), right->start() + to_move - 1, right, alloc); - // 4) Shift the values in the right node to their correct position. - params_type::move(alloc, right->slot(to_move), right->finish_slot(), - right->start_slot()); - - // 5) Destroy the now-empty to_move entries in the right node. - right->value_destroy_n(right->finish() - to_move, to_move, alloc); + // 4) Shift the values in the right node to their correct positions. + right->transfer_n(right->count() - to_move, right->start(), + right->start() + to_move, right, alloc); if (!leaf()) { // Move the child pointers from the right to the left node. @@ -1575,54 +1630,19 @@ void btree_node<P>::rebalance_left_to_right(const int to_move, // Lastly, a new delimiting value is moved from the left node into the // parent, and the remaining empty left node entries are destroyed. - if (right->count() >= to_move) { - // The original location of the right->count() values are sufficient to hold - // the new to_move entries from the parent and left node. - - // 1) Shift existing values in the right node to their correct positions. - right->uninitialized_move_n(to_move, right->finish() - to_move, - right->finish(), right, alloc); - for (slot_type *src = right->slot(right->finish() - to_move - 1), - *dest = right->slot(right->finish() - 1), - *end = right->start_slot(); - src >= end; --src, --dest) { - params_type::move(alloc, src, dest); - } + // 1) Shift existing values in the right node to their correct positions. + right->transfer_n_backward(right->count(), right->start() + to_move, + right->start(), right, alloc); - // 2) Move the delimiting value in the parent to the right node. - params_type::move(alloc, parent()->slot(position()), - right->slot(to_move - 1)); + // 2) Move the delimiting value in the parent to the right node. + right->transfer(right->start() + to_move - 1, position(), parent(), alloc); - // 3) Move the (to_move - 1) values from the left node to the right node. - params_type::move(alloc, slot(finish() - (to_move - 1)), finish_slot(), - right->start_slot()); - } else { - // The right node does not have enough initialized space to hold the new - // to_move entries, so part of them will move to uninitialized space. - - // 1) Shift existing values in the right node to their correct positions. - right->uninitialized_move_n(right->count(), right->start(), - right->start() + to_move, right, alloc); - - // 2) Move the delimiting value in the parent to the right node. - right->value_init(to_move - 1, alloc, parent()->slot(position())); - - // 3) Move the (to_move - 1) values from the left node to the right node. - const size_type uninitialized_remaining = to_move - right->count() - 1; - uninitialized_move_n(uninitialized_remaining, - finish() - uninitialized_remaining, right->finish(), - right, alloc); - params_type::move(alloc, slot(finish() - (to_move - 1)), - slot(finish() - uninitialized_remaining), - right->start_slot()); - } + // 3) Move the (to_move - 1) values from the left node to the right node. + right->transfer_n(to_move - 1, right->start(), finish() - (to_move - 1), this, + alloc); // 4) Move the new delimiting value to the parent from the left node. - params_type::move(alloc, slot(finish() - to_move), - parent()->slot(position())); - - // 5) Destroy the now-empty to_move entries in the left node. - value_destroy_n(finish() - to_move, to_move, alloc); + parent()->transfer(position(), finish() - to_move, this, alloc); if (!leaf()) { // Move the child pointers from the left to the right node. @@ -1662,10 +1682,7 @@ void btree_node<P>::split(const int insert_position, btree_node *dest, assert(count() >= 1); // Move values from the left sibling to the right sibling. - uninitialized_move_n(dest->count(), finish(), dest->start(), dest, alloc); - - // Destroy the now-empty entries in the left node. - value_destroy_n(finish(), dest->count(), alloc); + dest->transfer_n(dest->count(), dest->start(), finish(), this, alloc); // The split key is the largest value in the left sibling. --mutable_finish(); @@ -1692,11 +1709,7 @@ void btree_node<P>::merge(btree_node *src, allocator_type *alloc) { value_init(finish(), alloc, parent()->slot(position())); // Move the values from the right to the left node. - src->uninitialized_move_n(src->count(), src->start(), finish() + 1, this, - alloc); - - // Destroy the now-empty entries in the right node. - src->value_destroy_n(src->start(), src->count(), alloc); + transfer_n(src->count(), finish() + 1, src->start(), src, alloc); if (!leaf()) { // Move the child pointers from the right to the left node. @@ -1710,56 +1723,59 @@ 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>::swap(btree_node *x, allocator_type *alloc) { - using std::swap; - assert(leaf() == x->leaf()); - - // Determine which is the smaller/larger node. - btree_node *smaller = this, *larger = x; - if (smaller->count() > larger->count()) { - swap(smaller, larger); +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; } - - // Swap the values. - for (slot_type *a = smaller->start_slot(), *b = larger->start_slot(), - *end = smaller->finish_slot(); - a != end; ++a, ++b) { - params_type::swap(alloc, a, b); + if (node->count() == 0) { + deallocate(InternalSize(), node, alloc); + return; } - // Move values that can't be swapped. - const size_type to_move = larger->count() - smaller->count(); - larger->uninitialized_move_n(to_move, smaller->finish(), smaller->finish(), - smaller, alloc); - larger->value_destroy_n(smaller->finish(), to_move, alloc); + // The parent of the root of the subtree we are deleting. + btree_node *delete_root_parent = node->parent(); - if (!leaf()) { - // Swap the child pointers. - std::swap_ranges(&smaller->mutable_child(smaller->start()), - &smaller->mutable_child(smaller->finish() + 1), - &larger->mutable_child(larger->start())); - // Update swapped children's parent pointers. - int i = smaller->start(); - int j = larger->start(); - for (; i <= smaller->finish(); ++i, ++j) { - smaller->child(i)->set_parent(smaller); - larger->child(j)->set_parent(larger); - } - // Move the child pointers that couldn't be swapped. - for (; j <= larger->finish(); ++i, ++j) { - smaller->init_child(i, larger->child(j)); - larger->clear_child(j); - } + // 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()); } - - // Swap the `finish`s. - // TODO(ezb): with floating storage, will also need to swap starts. - swap(mutable_finish(), x->mutable_finish()); } //// @@ -1774,6 +1790,7 @@ void btree_iterator<N, R, P>::increment_slow() { position = node->position(); node = node->parent(); } + // TODO(ezb): assert we aren't incrementing end() instead of handling. if (position == node->finish()) { *this = save; } @@ -1797,6 +1814,7 @@ void btree_iterator<N, R, P>::decrement_slow() { position = node->position() - 1; node = node->parent(); } + // TODO(ezb): assert we aren't decrementing begin() instead of handling. if (position < node->start()) { *this = save; } @@ -1814,7 +1832,7 @@ 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 *x) { +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."); @@ -1822,11 +1840,11 @@ void btree<P>::copy_or_move_values_in_order(Btree *x) { // We can avoid key comparisons because we know the order of the // values is the same order we'll store them in. - auto iter = x->begin(); - if (iter == x->end()) return; + auto iter = other->begin(); + if (iter == other->end()) return; insert_multi(maybe_move_from_iterator(iter)); ++iter; - for (; iter != x->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)); @@ -1869,13 +1887,48 @@ 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 &x) : btree(x.key_comp(), x.allocator()) { - copy_or_move_values_in_order(&x); +btree<P>::btree(const btree &other) + : btree(other.key_comp(), other.allocator()) { + copy_or_move_values_in_order(&other); } template <typename P> -template <typename... Args> -auto btree<P>::insert_unique(const key_type &key, Args &&... args) +template <typename K> +auto btree<P>::equal_range(const K &key) -> std::pair<iterator, iterator> { + const iterator lower = lower_bound(key); + // TODO(ezb): we should be able to avoid this comparison when there's a + // three-way comparator. + if (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 are equivalent. + 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 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); @@ -1900,8 +1953,8 @@ 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()) { @@ -1925,14 +1978,23 @@ 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()) { @@ -1977,46 +2039,47 @@ void btree<P>::insert_iterator_multi(InputIterator b, InputIterator e) { } template <typename P> -auto btree<P>::operator=(const btree &x) -> btree & { - if (this != &x) { +auto btree<P>::operator=(const btree &other) -> btree & { + if (this != &other) { clear(); - *mutable_key_comp() = x.key_comp(); + *mutable_key_comp() = other.key_comp(); if (absl::allocator_traits< allocator_type>::propagate_on_container_copy_assignment::value) { - *mutable_allocator() = x.allocator(); + *mutable_allocator() = other.allocator(); } - copy_or_move_values_in_order(&x); + copy_or_move_values_in_order(&other); } return *this; } template <typename P> -auto btree<P>::operator=(btree &&x) noexcept -> btree & { - if (this != &x) { +auto btree<P>::operator=(btree &&other) noexcept -> btree & { + if (this != &other) { clear(); using std::swap; if (absl::allocator_traits< allocator_type>::propagate_on_container_copy_assignment::value) { // Note: `root_` also contains the allocator and the key comparator. - swap(root_, x.root_); - swap(rightmost_, x.rightmost_); - swap(size_, x.size_); + swap(root_, other.root_); + swap(rightmost_, other.rightmost_); + swap(size_, other.size_); } else { - if (allocator() == x.allocator()) { - swap(mutable_root(), x.mutable_root()); - swap(*mutable_key_comp(), *x.mutable_key_comp()); - swap(rightmost_, x.rightmost_); - swap(size_, x.size_); + if (allocator() == other.allocator()) { + swap(mutable_root(), other.mutable_root()); + swap(*mutable_key_comp(), *other.mutable_key_comp()); + swap(rightmost_, other.rightmost_); + swap(size_, other.size_); } else { // We aren't allowed to propagate the allocator and the allocator is // different so we can't take over its memory. We must move each element - // individually. We need both `x` and `this` to have `x`s key comparator - // while moving the values so we can't swap the key comparators. - *mutable_key_comp() = x.key_comp(); - copy_or_move_values_in_order(&x); + // individually. We need both `other` and `this` to have `other`s key + // 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); } } } @@ -2028,7 +2091,7 @@ 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); @@ -2040,7 +2103,7 @@ 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 @@ -2115,7 +2178,9 @@ 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)}; } @@ -2125,8 +2190,11 @@ 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); } @@ -2135,51 +2203,6 @@ 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); @@ -2207,7 +2230,7 @@ auto btree<P>::erase_multi(const K &key) -> size_type { 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(); @@ -2215,20 +2238,20 @@ void btree<P>::clear() { } template <typename P> -void btree<P>::swap(btree &x) { +void btree<P>::swap(btree &other) { using std::swap; if (absl::allocator_traits< allocator_type>::propagate_on_container_swap::value) { // Note: `root_` also contains the allocator and the key comparator. - swap(root_, x.root_); + swap(root_, other.root_); } else { // It's undefined behavior if the allocators are unequal here. - assert(allocator() == x.allocator()); - swap(mutable_root(), x.mutable_root()); - swap(*mutable_key_comp(), *x.mutable_key_comp()); + assert(allocator() == other.allocator()); + swap(mutable_root(), other.mutable_root()); + swap(*mutable_key_comp(), *other.mutable_key_comp()); } - swap(rightmost_, x.rightmost_); - swap(size_, x.size_); + swap(rightmost_, other.rightmost_); + swap(size_, other.size_); } template <typename P> @@ -2348,12 +2371,7 @@ 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> @@ -2410,21 +2428,20 @@ 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() = EmptyNode(); - rightmost_ = EmptyNode(); + 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> @@ -2452,7 +2469,8 @@ 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. if (max_count < kNodeValues) { @@ -2461,16 +2479,20 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args) assert(iter.node == root()); iter.node = new_leaf_root_node((std::min<int>)(kNodeValues, 2 * max_count)); - iter.node->swap(root(), mutable_allocator()); - delete_leaf_node(root()); - mutable_root() = iter.node; - rightmost_ = iter.node; + // Transfer the values from the old root to the new root. + node_type *old_root = root(); + node_type *new_root = iter.node; + new_root->transfer_n(old_root->count(), new_root->start(), + old_root->start(), old_root, alloc); + new_root->set_finish(old_root->finish()); + old_root->set_finish(old_root->start()); + node_type::clear_and_delete(old_root, alloc); + mutable_root() = rightmost_ = new_root; } else { rebalance_or_split(&iter); } } - iter.node->emplace_value(iter.position, mutable_allocator(), - std::forward<Args>(args)...); + iter.node->emplace_value(iter.position, alloc, std::forward<Args>(args)...); ++size_; return iter; } @@ -2568,18 +2590,6 @@ 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); |