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We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + + Copyright [yyyy] [name of copyright owner] + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. diff --git a/README.md b/README.md new file mode 100644 index 0000000..93ffdf7 --- /dev/null +++ b/README.md @@ -0,0 +1,36 @@ +# C++ B-tree + +Code in this repository is based on +[Google's B-tree implementation](https://code.google.com/archive/p/cpp-btree/). + +C++ B-tree is a template library that implements ordered in-memory containers +based on a B-tree data structure. Similar to the STL `std::map`, `std::set`, +`std::multimap`, and `std::multiset` templates, this library provides +`btree::map`, `btree::set`, `btree::multimap` and `btree::multiset`. + +This difers from the original project by Google in that containers behave more +like modern STL (C++17) and are an almost drop-in replacements (except for the +iterator invalidation, see below); including support for `emplace` and +`try_emplace` as well as values in the map not needing to have a default +constructor. + +C++ B-tree containers have a few advantages compared with the standard +containers, which are typically implemented using Red-Black trees. Nodes in a +Red-Black tree require three pointers per entry (plus 1 bit), whereas B-trees +on average make use of fewer than one pointer per entry, leading to +**significant memory savings**. For example, a `set` has an overhead +of 16 bytes for every 4 byte set element (on a 32-bit operating system); the +corresponding `btree::set` has an overhead of around 1 byte per set +element. + +B-trees are widely known as data structures for secondary storage, because they +keep disk seeks to a minimum. For an in-memory data structure, the same property +yields a performance boost by keeping cache-line misses to a minimum. C++ B-tree +containers make better use of the cache by performing multiple key-comparisons +per node when searching the tree. Although B-tree algorithms are more complex, +compared with the Red-Black tree algorithms, the improvement in cache behavior +may account for a **significant speedup** in accessing large containers. + +The C++ B-tree containers are not without drawbacks, however. Unlike the +standard STL containers, modifying a C++ B-tree container +**invalidates all outstanding iterators** on that container. diff --git a/btree/btree.h b/btree/btree.h new file mode 100644 index 0000000..1a4fc03 --- /dev/null +++ b/btree/btree.h @@ -0,0 +1,3107 @@ +/* + * Copyright (c) 2019 German Mendez Bravo (Kronuz) + * Copyright (c) 2013 Google Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * + * A btree implementation of the STL set and map interfaces. A btree is both + * smaller and faster than STL set/map. The red-black tree implementation of + * STL set/map has an overhead of 3 pointers (left, right and parent) plus the + * node color information for each stored value. So a set consumes 20 + * bytes for each value stored. This btree implementation stores multiple + * values on fixed size nodes (usually 256 bytes) and doesn't store child + * pointers for leaf nodes. The result is that a btree::set may use much + * less memory per stored value. For the random insertion benchmark in + * btree_test.cc, a btree::set with node-size of 256 uses 4.9 bytes per + * stored value. + * + * The packing of multiple values on to each node of a btree has another effect + * besides better space utilization: better cache locality due to fewer cache + * lines being accessed. Better cache locality translates into faster + * operations. + * + * CAVEATS + * + * Insertions and deletions on a btree can cause splitting, merging or + * rebalancing of btree nodes. And even without these operations, insertions + * and deletions on a btree will move values around within a node. In both + * cases, the result is that insertions and deletions can invalidate iterators + * pointing to values other than the one being inserted/deleted. This is + * notably different from STL set/map which takes care to not invalidate + * iterators on insert/erase except, of course, for iterators pointing to the + * value being erased. A partial workaround when erasing is available: + * erase() returns an iterator pointing to the item just after the one that was + * erased (or end() if none exists). See also safe_btree. + * + * PERFORMANCE + * + * btree_bench --benchmarks=. 2>&1 | ./benchmarks.awk + * + * Run on pmattis-warp.nyc (4 X 2200 MHz CPUs); 2010/03/04-15:23:06 + * Benchmark STL(ns) B-Tree(ns) @ + * -------------------------------------------------------- + * BM_set_int32_insert 1516 608 +59.89% <256> [40.0, 5.2] + * BM_set_int32_lookup 1160 414 +64.31% <256> [40.0, 5.2] + * BM_set_int32_fulllookup 960 410 +57.29% <256> [40.0, 4.4] + * BM_set_int32_delete 1741 528 +69.67% <256> [40.0, 5.2] + * BM_set_int32_queueaddrem 3078 1046 +66.02% <256> [40.0, 5.5] + * BM_set_int32_mixedaddrem 3600 1384 +61.56% <256> [40.0, 5.3] + * BM_set_int32_fifo 227 113 +50.22% <256> [40.0, 4.4] + * BM_set_int32_fwditer 158 26 +83.54% <256> [40.0, 5.2] + * BM_map_int32_insert 1551 636 +58.99% <256> [48.0, 10.5] + * BM_map_int32_lookup 1200 508 +57.67% <256> [48.0, 10.5] + * BM_map_int32_fulllookup 989 487 +50.76% <256> [48.0, 8.8] + * BM_map_int32_delete 1794 628 +64.99% <256> [48.0, 10.5] + * BM_map_int32_queueaddrem 3189 1266 +60.30% <256> [48.0, 11.6] + * BM_map_int32_mixedaddrem 3822 1623 +57.54% <256> [48.0, 10.9] + * BM_map_int32_fifo 151 134 +11.26% <256> [48.0, 8.8] + * BM_map_int32_fwditer 161 32 +80.12% <256> [48.0, 10.5] + * BM_set_int64_insert 1546 636 +58.86% <256> [40.0, 10.5] + * BM_set_int64_lookup 1200 512 +57.33% <256> [40.0, 10.5] + * BM_set_int64_fulllookup 971 487 +49.85% <256> [40.0, 8.8] + * BM_set_int64_delete 1745 616 +64.70% <256> [40.0, 10.5] + * BM_set_int64_queueaddrem 3163 1195 +62.22% <256> [40.0, 11.6] + * BM_set_int64_mixedaddrem 3760 1564 +58.40% <256> [40.0, 10.9] + * BM_set_int64_fifo 146 103 +29.45% <256> [40.0, 8.8] + * BM_set_int64_fwditer 162 31 +80.86% <256> [40.0, 10.5] + * BM_map_int64_insert 1551 720 +53.58% <256> [48.0, 20.7] + * BM_map_int64_lookup 1214 612 +49.59% <256> [48.0, 20.7] + * BM_map_int64_fulllookup 994 592 +40.44% <256> [48.0, 17.2] + * BM_map_int64_delete 1778 764 +57.03% <256> [48.0, 20.7] + * BM_map_int64_queueaddrem 3189 1547 +51.49% <256> [48.0, 20.9] + * BM_map_int64_mixedaddrem 3779 1887 +50.07% <256> [48.0, 21.6] + * BM_map_int64_fifo 147 145 +1.36% <256> [48.0, 17.2] + * BM_map_int64_fwditer 162 41 +74.69% <256> [48.0, 20.7] + * BM_set_string_insert 1989 1966 +1.16% <256> [64.0, 44.5] + * BM_set_string_lookup 1709 1600 +6.38% <256> [64.0, 44.5] + * BM_set_string_fulllookup 1573 1529 +2.80% <256> [64.0, 35.4] + * BM_set_string_delete 2520 1920 +23.81% <256> [64.0, 44.5] + * BM_set_string_queueaddrem 4706 4309 +8.44% <256> [64.0, 48.3] + * BM_set_string_mixedaddrem 5080 4654 +8.39% <256> [64.0, 46.7] + * BM_set_string_fifo 318 512 -61.01% <256> [64.0, 35.4] + * BM_set_string_fwditer 182 93 +48.90% <256> [64.0, 44.5] + * BM_map_string_insert 2600 2227 +14.35% <256> [72.0, 55.8] + * BM_map_string_lookup 2068 1730 +16.34% <256> [72.0, 55.8] + * BM_map_string_fulllookup 1859 1618 +12.96% <256> [72.0, 44.0] + * BM_map_string_delete 3168 2080 +34.34% <256> [72.0, 55.8] + * BM_map_string_queueaddrem 5840 4701 +19.50% <256> [72.0, 59.4] + * BM_map_string_mixedaddrem 6400 5200 +18.75% <256> [72.0, 57.8] + * BM_map_string_fifo 398 596 -49.75% <256> [72.0, 44.0] + * BM_map_string_fwditer 243 113 +53.50% <256> [72.0, 55.8] + */ + +#ifndef BTREE_BTREE_H__ +#define BTREE_BTREE_H__ + +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +namespace btree { + +// Inside a btree method, if we just call swap(), it will choose the +// btree::swap method, which we don't want. And we can't say ::swap +// because then MSVC won't pickup any std::swap() implementations. We +// can't just use std::swap() directly because then we don't get the +// specialization for types outside the std namespace. So the solution +// is to have a special swap helper function whose name doesn't +// collide with other swap functions defined by the btree classes. +template +inline void btree_swap_helper(T& a, T& b) { + using std::swap; + swap(a, b); +} + +// Types small_ and big_ are promise that sizeof(small_) < sizeof(big_) +typedef char small_; + +struct big_ { + char dummy[2]; +}; + +// A compile-time assertion. +template +struct CompileAssert { }; + +#define COMPILE_ASSERT(expr, msg) \ + typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1] + +struct btree_extract_key_fail_tag { }; +struct btree_extract_key_self_tag { }; +struct btree_extract_key_first_tag { }; + +template ::type>::type> +struct btree_can_extract_key + : std::conditional::value, + btree_extract_key_self_tag, + btree_extract_key_fail_tag>::type { }; + +template +struct btree_can_extract_key<_Pair, Key, std::pair> + : std::conditional::type, Key>::value, + btree_extract_key_first_tag, + btree_extract_key_fail_tag>::type { }; + +// btree_can_extract_map_key uses true_type/false_type instead of the tags. +// It returns true if Key != ContainerValueType (the container is a map not a set) +// and ValueType == Key. +template ::type>::type> +struct btree_can_extract_map_key : std::integral_constant::value> { }; + +// This specialization returns btree_extract_key_fail_tag for non-map containers +// because Key == ContainerValueType +template +struct btree_can_extract_map_key : std::false_type { }; + +// A helper type used to indicate that a key-compare-to functor has been +// provided. A user can specify a key-compare-to functor by doing: +// +// struct MyStringComparer +// : public util::btree::btree_key_compare_to_tag { +// int operator()(const string& a, const string& b) const { +// return a.compare(b); +// } +// }; +// +// Note that the return type is an int and not a bool. There is a +// COMPILE_ASSERT which enforces this return type. +struct btree_key_compare_to_tag { }; + +// A helper class that indicates if the Compare parameter is derived from +// btree_key_compare_to_tag. +template +struct btree_is_key_compare_to : public std::is_convertible { }; + +// 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 class is specialized for +// less and greater. The btree_key_compare_to_adapter +// class is provided so that btree users automatically get the more +// efficient compare-to code when using common google string types +// with common comparison functors. +template +struct btree_key_compare_to_adapter : Compare { + btree_key_compare_to_adapter() { } + btree_key_compare_to_adapter(const Compare& c) : Compare(c) { } + btree_key_compare_to_adapter(const btree_key_compare_to_adapter& c) + : Compare(c) { + } +}; + +template <> +struct btree_key_compare_to_adapter> : public btree_key_compare_to_tag { + btree_key_compare_to_adapter() { } + btree_key_compare_to_adapter(const std::less&) { } + btree_key_compare_to_adapter(const btree_key_compare_to_adapter>&) { } + int operator()(const std::string& a, const std::string& b) const { + return a.compare(b); + } +}; + +template <> +struct btree_key_compare_to_adapter> : public btree_key_compare_to_tag { + btree_key_compare_to_adapter() { } + btree_key_compare_to_adapter(const std::greater&) { } + btree_key_compare_to_adapter(const btree_key_compare_to_adapter>&) { } + int operator()(const std::string& a, const std::string& b) const { + return b.compare(a); + } +}; + +// A helper class that allows a compare-to functor to behave like a plain +// compare functor. This specialization is used when we do not have a +// compare-to functor. +template +struct btree_key_comparer { + btree_key_comparer() { } + btree_key_comparer(Compare c) : comp(c) { } + static bool bool_compare(const Compare& comp, const Key& x, const Key& y) { + return comp(x, y); + } + bool operator()(const Key& x, const Key& y) const { + return bool_compare(comp, x, y); + } + Compare comp; +}; + +// A specialization of btree_key_comparer when a compare-to functor is +// present. We need a plain (boolean) comparison in some parts of the btree +// code, such as insert-with-hint. +template +struct btree_key_comparer { + btree_key_comparer() { } + btree_key_comparer(Compare c) : comp(c) { } + static bool bool_compare(const Compare& comp, const Key& x, const Key& y) { + return comp(x, y) < 0; + } + bool operator()(const Key& x, const Key& y) const { + return bool_compare(comp, x, y); + } + Compare comp; +}; + +// A helper function to compare to keys using the specified compare +// functor. This dispatches to the appropriate btree_key_comparer comparison, +// depending on whether we have a compare-to functor or not (which depends on +// whether Compare is derived from btree_key_compare_to_tag). +template +static bool btree_compare_keys(const Compare& comp, const Key& x, const Key& y) { + typedef btree_key_comparer::value> key_comparer; + return key_comparer::bool_compare(comp, x, y); +} + +template +struct btree_common_params { + // If Compare is derived from btree_key_compare_to_tag then use it as the + // key_compare type. Otherwise, use btree_key_compare_to_adapter<> which will + // fall-back to Compare if we don't have an appropriate specialization. + typedef std::conditional_t::value, + Compare, + btree_key_compare_to_adapter> key_compare; + // A type which indicates if we have a key-compare-to functor or a plain old + // key-compare functor. + typedef btree_is_key_compare_to is_key_compare_to; + + typedef Key key_type; + typedef ssize_t size_type; + typedef ptrdiff_t difference_type; + + typedef Alloc allocator_type; + typedef std::allocator_traits allocator_traits; + typedef typename allocator_traits::template rebind_alloc internal_allocator_type; + typedef std::allocator_traits internal_allocator_traits; + + enum { + kTargetNodeSize = TargetNodeSize, + + // Available space for values. This is largest for leaf nodes, + // which has overhead no fewer than two pointers. + kNodeValueSpace = TargetNodeSize - 2 * sizeof(void*), + }; + + // This is an integral type large enough to hold as many + // ValueSize-values as will fit a node of TargetNodeSize bytes. + typedef std::conditional_t<(kNodeValueSpace / ValueSize) >= 256, + uint16_t, + uint8_t> node_count_type; +}; + +// A parameters structure for holding the type parameters for a map. +template +struct btree_map_params : public btree_common_params { + typedef Data data_type; + typedef Data mapped_type; + typedef std::pair value_type; + typedef value_type* pointer; + typedef const value_type* const_pointer; + typedef value_type& reference; + typedef const value_type& const_reference; + + enum { + kValueSize = sizeof(Key) + sizeof(data_type), + }; + + static void swap(value_type& a, value_type& b) { + btree_swap_helper(const_cast(a.first), const_cast(b.first)); + btree_swap_helper(a.second, b.second); + } + + static const Key& get_key(const value_type& x) { + return x.first; + } +}; + +// A parameters structure for holding the type parameters for a btree_set. +template +struct btree_set_params : public btree_common_params { + typedef std::false_type data_type; + typedef std::false_type mapped_type; + typedef Key value_type; + typedef value_type* pointer; + typedef const value_type* const_pointer; + typedef value_type& reference; + typedef const value_type& const_reference; + + enum { + kValueSize = sizeof(Key), + }; + + static void swap(value_type& a, value_type& b) { + btree_swap_helper(a, b); + } + + static const Key& get_key(const value_type& x) { + return x; + } +}; + +// An adapter class that converts a lower-bound compare into an upper-bound +// compare. +template +struct btree_upper_bound_adapter : public Compare { + btree_upper_bound_adapter(Compare c) : Compare(c) { } + bool operator()(const Key& a, const Key& b) const { + return !static_cast(*this)(b, a); + } +}; + +template +struct btree_upper_bound_compare_to_adapter : public CompareTo { + btree_upper_bound_compare_to_adapter(CompareTo c) : CompareTo(c) { } + int operator()(const Key& a, const Key& b) const { + return static_cast(*this)(b, a); + } +}; + +// Dispatch helper class for using linear search with plain compare. +template +struct btree_linear_search_plain_compare { + static int lower_bound(const K& k, const N& n, Compare comp) { + return n.linear_search_plain_compare(k, 0, n.count(), comp); + } + static int upper_bound(const K& k, const N& n, Compare comp) { + typedef btree_upper_bound_adapter upper_compare; + return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp)); + } +}; + +// Dispatch helper class for using linear search with compare-to +template +struct btree_linear_search_compare_to { + static int lower_bound(const K& k, const N& n, CompareTo comp) { + return n.linear_search_compare_to(k, 0, n.count(), comp); + } + static int upper_bound(const K& k, const N& n, CompareTo comp) { + typedef btree_upper_bound_adapter> upper_compare; + return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp)); + } +}; + +// Dispatch helper class for using binary search with plain compare. +template +struct btree_binary_search_plain_compare { + static int lower_bound(const K& k, const N& n, Compare comp) { + return n.binary_search_plain_compare(k, 0, n.count(), comp); + } + static int upper_bound(const K& k, const N& n, Compare comp) { + typedef btree_upper_bound_adapter upper_compare; + return n.binary_search_plain_compare(k, 0, n.count(), upper_compare(comp)); + } +}; + +// Dispatch helper class for using binary search with compare-to. +template +struct btree_binary_search_compare_to { + static int lower_bound(const K& k, const N& n, CompareTo /*comp*/) { + return n.binary_search_compare_to(k, 0, n.count(), CompareTo()); + } + static int upper_bound(const K& k, const N& n, CompareTo comp) { + typedef btree_upper_bound_adapter> upper_compare; + return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp)); + } +}; + +// A node in the btree holding. The same node type is used for both internal +// and leaf nodes in the btree, though the nodes are allocated in such a way +// that the children array is only valid in internal nodes. +template +class btree_node { +public: + typedef Params params_type; + typedef btree_node self_type; + typedef typename Params::key_type key_type; + typedef typename Params::data_type data_type; + typedef typename Params::value_type value_type; + typedef typename Params::pointer pointer; + typedef typename Params::const_pointer const_pointer; + typedef typename Params::reference reference; + typedef typename Params::const_reference const_reference; + typedef typename Params::key_compare key_compare; + typedef typename Params::size_type size_type; + typedef typename Params::difference_type difference_type; + + typedef typename Params::allocator_type allocator_type; + typedef typename Params::allocator_traits allocator_traits; + + // Typedefs for the various types of node searches. + typedef btree_linear_search_plain_compare linear_search_plain_compare_type; + typedef btree_linear_search_compare_to linear_search_compare_to_type; + typedef btree_binary_search_plain_compare binary_search_plain_compare_type; + typedef btree_binary_search_compare_to binary_search_compare_to_type; + // If we have a valid key-compare-to type, use linear_search_compare_to, + // otherwise use linear_search_plain_compare. + typedef std::conditional_t linear_search_type; + // If we have a valid key-compare-to type, use binary_search_compare_to, + // otherwise use binary_search_plain_compare. + typedef std::conditional_t binary_search_type; + // If the key is an integral or floating point type, use linear search which + // is faster than binary search for such types. Might be wise to also + // configure linear search based on node-size. + typedef std::conditional_t::value || std::is_floating_point::value, + linear_search_type, binary_search_type> search_type; + + struct base_fields { + typedef typename Params::node_count_type field_type; + + // A boolean indicating whether the node is a leaf or not. + bool leaf; + // The position of the node in the node's parent. + field_type position; + // The maximum number of values the node can hold. + field_type max_count; + // The count of the number of values in the node. + field_type count; + // A pointer to the node's parent. + btree_node* parent; + }; + + enum { + kValueSize = params_type::kValueSize, + kTargetNodeSize = params_type::kTargetNodeSize, + + // Compute how many values we can fit onto a leaf node. + kNodeTargetValues = (kTargetNodeSize - sizeof(base_fields)) / kValueSize, + // We need a minimum of 3 values per internal node in order to perform + // splitting (1 value for the two nodes involved in the split and 1 value + // propagated to the parent as the delimiter for the split). + kNodeValues = kNodeTargetValues >= 3 ? kNodeTargetValues : 3, + + kExactMatch = 1 << 30, + kMatchMask = kExactMatch - 1, + }; + + struct leaf_fields : public base_fields { + // The array of values. Only the first count of these values have been + // constructed and are valid. + value_type values[kNodeValues]; + }; + + struct internal_fields : public leaf_fields { + // The array of child pointers. The keys in children_[i] are all less than + // key(i). The keys in children_[i + 1] are all greater than key(i). There + // are always count + 1 children. + btree_node* children[kNodeValues + 1]; + }; + + struct root_fields : public internal_fields { + btree_node* rightmost; + size_type size; + }; + +public: + // Getter/setter for whether this is a leaf node or not. This value doesn't + // change after the node is created. + bool is_leaf() const { + return fields_.leaf; + } + + // Getter for the position of this node in its parent. + int position() const { + return fields_.position; + } + + // Getter/setter for the number of values stored in this node. + int count() const { + return fields_.count; + } + void set_count(int v) { + assert(v >= 0); + assert(v <= fields_.max_count); + fields_.count = v; + } + int max_count() const { + return fields_.max_count; + } + + // Getter for the parent of this node. + btree_node* get_parent() const { + return fields_.parent; + } + // Getter for whether the node is the root of the tree. The parent of the + // root of the tree is the leftmost node in the tree which is guaranteed to + // be a leaf. + bool is_root() const { + return fields_.parent->is_leaf(); + } + void make_root() { + assert(fields_.parent->is_root()); + fields_.parent = fields_.parent->get_parent(); + } + + // Getter for the rightmost root node field. Only valid on the root node. + btree_node* rightmost() const { + return fields_.rightmost; + } + btree_node*& __rightmost() { + return fields_.rightmost; + } + + // Getter for the size root node field. Only valid on the root node. + size_type size() const { + return fields_.size; + } + size_type& __size() { + return fields_.size; + } + + // Getters for the key/value at position i in the node. + const key_type& key(int i) const { + return params_type::get_key(fields_.values[i]); + } + reference value(int i) { + return reinterpret_cast(fields_.values[i]); + } + const_reference value(int i) const { + return reinterpret_cast(fields_.values[i]); + } + + // Swap value i in this node with value j in node x. + void swap_value(int i, btree_node* x, int j) { + assert(x != this || i != j); + params_type::swap(fields_.values[i], x->fields_.values[j]); + } + + // Swap value i in this node with value i in node x. + void swap_value(int i, btree_node* x) { + assert(x != this); + params_type::swap(fields_.values[i], x->fields_.values[i]); + } + + // Swap value i with value j. + void swap_value(int i, int j) { + assert(i != j); + params_type::swap(fields_.values[i], fields_.values[j]); + } + + // Move value i in this node to value j in node x. + void move_value(int i, btree_node* x, int j) { + assert(x != this || i != j); + x->construct_value(j, std::move(fields_.values[i])); + destroy_value(i); + } + + // Move value i in this node to value i in node x. + void move_value(int i, btree_node* x) { + assert(x != this); + x->construct_value(i, std::move(fields_.values[i])); + destroy_value(i); + } + + // Move value i to value j. + void move_value(int i, int j) { + assert(i != j); + construct_value(j, std::move(fields_.values[i])); + destroy_value(i); + } + + // Getters/setter for the child at position i in the node. + btree_node* child(int i) const { + assert(!is_leaf()); + return fields_.children[i]; + } + +#ifndef NDEBUG + void reset_child(int i) { + assert(!is_leaf()); + fields_.children[i] = nullptr; + } +#else + void reset_child(int) { + } +#endif + + void set_child(int i, btree_node* c) { + assert(!is_leaf()); + assert(c != nullptr); + fields_.children[i] = c; + c->fields_.parent = this; + c->fields_.position = i; + } + + // Swap child i in this node with child j in node x. + void swap_child(int i, btree_node* x, int j) { + assert(x != this || i != j); + assert(!is_leaf()); + assert(!x->is_leaf()); + assert(fields_.children[i] != nullptr); + assert(x->fields_.children[j] != nullptr); + auto& a = fields_.children[i]; + auto& b = x->fields_.children[j]; + btree_swap_helper(a, b); + a->fields_.parent = this; + a->fields_.position = i; + b->fields_.parent = x; + b->fields_.position = j; + } + + // Swap child i in this node with child i in node x. + void swap_child(int i, btree_node* x) { + assert(x != this); + assert(!is_leaf()); + assert(!x->is_leaf()); + assert(fields_.children[i] != nullptr); + assert(x->fields_.children[i] != nullptr); + auto& a = fields_.children[i]; + auto& b = x->fields_.children[i]; + btree_swap_helper(a, b); + a->fields_.parent = this; + b->fields_.parent = x; + } + + // Swap child i with child j. + void swap_child(int i, int j) { + assert(i != j); + assert(!is_leaf()); + assert(fields_.children[i] != nullptr); + assert(fields_.children[j] != nullptr); + auto& a = fields_.children[i]; + auto& b = fields_.children[j]; + btree_swap_helper(a, b); + a->fields_.position = i; + b->fields_.position = j; + } + + // Move child i in this node to child j in node x. + void move_child(int i, btree_node* x, int j) { + assert(x != this || i != j); + assert(!is_leaf()); + assert(!x->is_leaf()); + assert(fields_.children[i] != nullptr); + auto c = fields_.children[i]; + x->fields_.children[j] = c; + c->fields_.position = j; + c->fields_.parent = x; +#ifndef NDEBUG + fields_.children[i] = nullptr; +#endif + } + + // Move child i in this node to child i in node x. + void move_child(int i, btree_node* x) { + assert(x != this); + assert(!is_leaf()); + assert(!x->is_leaf()); + assert(fields_.children[i] != nullptr); + auto c = fields_.children[i]; + x->fields_.children[i] = c; + c->fields_.parent = x; +#ifndef NDEBUG + fields_.children[i] = nullptr; +#endif + } + + // Move child i to child j. + void move_child(int i, int j) { + assert(i != j); + assert(!is_leaf()); + assert(fields_.children[i] != nullptr); + auto c = fields_.children[i]; + fields_.children[j] = c; + c->fields_.position = j; +#ifndef NDEBUG + fields_.children[i] = nullptr; +#endif + } + + // Returns the position of the first value whose key is not less than k. + template + int lower_bound(const key_type& k, const Compare& comp) const { + return search_type::lower_bound(k, *this, comp); + } + // Returns the position of the first value whose key is greater than k. + template + int upper_bound(const key_type& k, const Compare& comp) const { + return search_type::upper_bound(k, *this, comp); + } + + // Returns the position of the first value whose key is not less than k + // using linear search performed using plain compare. + template + int linear_search_plain_compare(const key_type& k, int s, int e, const Compare& comp) const { + while (s < e) { + if (!btree_compare_keys(comp, key(s), k)) { + break; + } + ++s; + } + return s; + } + + // Returns the position of the first value whose key is not less than k + // using linear search performed using compare-to. + template + int linear_search_compare_to(const key_type& k, int s, int e, const Compare& comp) const { + while (s < e) { + int c = comp(key(s), k); + if (c == 0) { + return s | kExactMatch; + } else if (c > 0) { + break; + } + ++s; + } + return s; + } + + // Returns the position of the first value whose key is not less than k + // using binary search performed using plain compare. + template + int binary_search_plain_compare(const key_type& k, int s, int e, const Compare& comp) const { + while (s != e) { + int mid = (s + e) / 2; + if (btree_compare_keys(comp, key(mid), k)) { + s = mid + 1; + } else { + e = mid; + } + } + return s; + } + + // Returns the position of the first value whose key is not less than k + // using binary search performed using compare-to. + template + int binary_search_compare_to(const key_type& k, int s, int e, const CompareTo& comp) const { + while (s != e) { + int mid = (s + e) / 2; + int c = comp(key(mid), k); + if (c < 0) { + s = mid + 1; + } else if (c > 0) { + e = mid; + } else { + // Need to return the first value whose key is not less than k, + // which requires continuing the binary search. Note that we are + // guaranteed that the result is an exact match because + // if "key(mid-1) < k" the call to binary_search_compare_to() + // will return "mid". + s = binary_search_compare_to(k, s, mid, comp); + return s | kExactMatch; + } + } + return s; + } + + // Inserts the value x at position i, shifting all existing values + // and children at positions >= i to the right by 1. + template + void insert_value(int i, 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); + + // Rebalances a node with its right sibling. + void rebalance_right_to_left(btree_node* sibling, int to_move); + void rebalance_left_to_right(btree_node* sibling, int to_move); + + // Splits a node, moving a portion of the node's values to its right sibling. + void split(btree_node* sibling, int insert_position); + + // 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); + + // Swap the contents of "this" and "src". + void swap(btree_node* src); + + // Node allocation/deletion routines. + static btree_node* init_leaf(leaf_fields* f, btree_node* parent, int max_count) { + btree_node* n = reinterpret_cast(f); + f->leaf = 1; + f->position = 0; + f->max_count = max_count; + f->count = 0; + f->parent = parent; + assert(memset(&f->values, 0, max_count * sizeof(value_type))); + return n; + } + + static btree_node* init_internal(internal_fields* f, btree_node* parent) { + btree_node* n = init_leaf(f, parent, kNodeValues); + f->leaf = 0; + assert(memset(f->children, 0, sizeof(f->children))); + return n; + } + + static btree_node* init_root(root_fields* f, btree_node* parent) { + btree_node* n = init_internal(f, parent); + f->rightmost = parent; + f->size = parent->count(); + return n; + } + + void destroy() { + for (int i = 0; i < count(); ++i) { + destroy_value(i); + } + } + +private: + static constexpr const char zero_value[sizeof(value_type)] = {}; + + template + void construct_value(value_type* v, Args&&... args) { + assert(memcmp(zero_value, v, sizeof(value_type)) == 0); + + new (v) value_type(std::forward(args)...); + // FIXME: The above should use allocator_traits, but allocator + // object is not available here at the nodes, is in the tree: + // allocator_type& alloc = allocator(); + // allocator_traits::construct(alloc, v, std::forward(args)...); + } + + template + void construct_value(int i, Args&&... args) { + assert(i >= 0); + assert(i < fields_.max_count); + construct_value(&fields_.values[i], std::forward(args)...); + } + + void destroy_value(value_type* v) { + v->~value_type(); + // FIXME: The above should use allocator_traits, but allocator + // object is not available here at the nodes, is in the tree: + // allocator_type& alloc = allocator(); + // allocator_traits::destroy(alloc, v); + + assert(memcpy(v, zero_value, sizeof(value_type))); + } + + void destroy_value(int i) { + assert(i >= 0); + assert(i < fields_.max_count); + destroy_value(&fields_.values[i]); + } + +private: + root_fields fields_; + +private: + btree_node(const btree_node&); + void operator=(const btree_node&); +}; + +template +class btree_iterator { +public: + typedef typename Node::key_type key_type; + typedef typename Node::size_type size_type; + typedef typename Node::difference_type difference_type; + typedef typename Node::params_type params_type; + + typedef Node node_type; + typedef typename std::remove_const::type normal_node; + typedef const Node const_node; + typedef typename params_type::value_type value_type; + typedef typename params_type::pointer normal_pointer; + typedef typename params_type::reference normal_reference; + typedef typename params_type::const_pointer const_pointer; + typedef typename params_type::const_reference const_reference; + + typedef Pointer pointer; + typedef Reference reference; + typedef std::bidirectional_iterator_tag iterator_category; + + typedef btree_iterator iterator; + typedef btree_iterator const_iterator; + typedef btree_iterator self_type; + + btree_iterator() + : node(nullptr), + position(-1) { + } + btree_iterator(const iterator& x) + : node(x.node), + position(x.position) { + } + + bool operator==(const const_iterator& x) const { + return node == x.node && position == x.position; + } + bool operator!=(const const_iterator& x) const { + return node != x.node || position != x.position; + } + + // Accessors for the key/value the iterator is pointing at. + const key_type& key() const { + return node->key(position); + } + reference operator*() const { + return node->value(position); + } + pointer operator->() const { + return &node->value(position); + } + + self_type& operator++() { + increment(); + return *this; + } + self_type& operator--() { + decrement(); + return *this; + } + self_type operator++(int) { + self_type tmp =* this; + ++*this; + return tmp; + } + self_type operator--(int) { + self_type tmp =* this; + --*this; + return tmp; + } + +private: + btree_iterator(Node* n, int p) + : node(const_cast(n)), + position(p) { + } + + // Increment/decrement the iterator. + void increment() { + if (node->is_leaf() && ++position < node->count()) { + return; + } + increment_slow(); + } + void increment_by(int count); + void increment_slow(); + + void decrement() { + if (node->is_leaf() && --position >= 0) { + return; + } + decrement_slow(); + } + void decrement_slow(); + + // The node in the tree the iterator is pointing at. + normal_node* node; + // The position within the node of the tree the iterator is pointing at. + int position; + + template friend class btree; + friend iterator; + friend const_iterator; +}; + +// Dispatch helper class for using btree::internal_locate with plain compare. +struct btree_internal_locate_plain_compare { + template + static std::pair dispatch(const K& k, const T& t, Iter iter) { + return t.internal_locate_plain_compare(k, iter); + } +}; + +// Dispatch helper class for using btree::internal_locate with compare-to. +struct btree_internal_locate_compare_to { + template + static std::pair dispatch(const K& k, const T& t, Iter iter) { + return t.internal_locate_compare_to(k, iter); + } +}; + +template +class btree : public Params::key_compare { + typedef btree self_type; + typedef btree_node node_type; + typedef typename node_type::base_fields base_fields; + typedef typename node_type::leaf_fields leaf_fields; + typedef typename node_type::internal_fields internal_fields; + typedef typename node_type::root_fields root_fields; + typedef typename Params::is_key_compare_to is_key_compare_to; + + friend struct btree_internal_locate_plain_compare; + friend struct btree_internal_locate_compare_to; + typedef std::conditional_t internal_locate_type; + + enum { + kNodeValues = node_type::kNodeValues, + kMinNodeValues = kNodeValues / 2, + kValueSize = node_type::kValueSize, + kExactMatch = node_type::kExactMatch, + kMatchMask = node_type::kMatchMask, + }; + + // A helper class to get the empty base class optimization for 0-size + // allocators. Base is internal_allocator_type. + // (e.g. empty_base_handle). If Base is + // 0-size, the compiler doesn't have to reserve any space for it and + // sizeof(empty_base_handle) will simply be sizeof(Data). Google [empty base + // class optimization] for more details. + template + struct empty_base_handle : public Base { + empty_base_handle(const Base& b, const Data& d) + : Base(b), + data(d) { + } + Data data; + }; + + struct node_stats { + node_stats(ssize_t l, ssize_t i) + : leaf_nodes(l), + internal_nodes(i) { + } + + node_stats& operator+=(const node_stats& x) { + leaf_nodes += x.leaf_nodes; + internal_nodes += x.internal_nodes; + return *this; + } + + ssize_t leaf_nodes; + ssize_t internal_nodes; + }; + +public: + typedef Params params_type; + typedef typename Params::key_type key_type; + typedef typename Params::data_type data_type; + typedef typename Params::mapped_type mapped_type; + typedef typename Params::value_type value_type; + typedef typename Params::key_compare key_compare; + typedef typename Params::pointer pointer; + typedef typename Params::const_pointer const_pointer; + typedef typename Params::reference reference; + typedef typename Params::const_reference const_reference; + typedef typename Params::size_type size_type; + typedef typename Params::difference_type difference_type; + typedef btree_iterator iterator; + typedef typename iterator::const_iterator const_iterator; + typedef std::reverse_iterator const_reverse_iterator; + typedef std::reverse_iterator reverse_iterator; + + typedef typename Params::allocator_type allocator_type; + typedef typename Params::allocator_traits allocator_traits; + typedef typename Params::internal_allocator_type internal_allocator_type; + typedef typename Params::internal_allocator_traits internal_allocator_traits; + +public: + // Default constructor. + btree(const key_compare& comp, const allocator_type& alloc); + + // Copy constructor. + btree(const self_type& x); + + // Destructor. + ~btree() { + clear(); + } + + // Iterator routines. + iterator begin() { + return iterator(leftmost(), 0); + } + const_iterator begin() const { + return const_iterator(leftmost(), 0); + } + const_iterator cbegin() const { + return const_iterator(leftmost(), 0); + } + iterator end() { + return iterator(rightmost(), rightmost() ? rightmost()->count() : 0); + } + const_iterator end() const { + return const_iterator(rightmost(), rightmost() ? rightmost()->count() : 0); + } + const_iterator cend() const { + return const_iterator(rightmost(), rightmost() ? rightmost()->count() : 0); + } + reverse_iterator rbegin() { + return reverse_iterator(end()); + } + const_reverse_iterator rbegin() const { + return const_reverse_iterator(end()); + } + const_reverse_iterator crbegin() const { + return const_reverse_iterator(end()); + } + reverse_iterator rend() { + return reverse_iterator(begin()); + } + const_reverse_iterator rend() const { + return const_reverse_iterator(begin()); + } + const_reverse_iterator crend() const { + return const_reverse_iterator(begin()); + } + + // Finds the first element whose key is not less than key. + iterator lower_bound(const key_type& key) { + return internal_end(internal_lower_bound(key, iterator(root(), 0))); + } + const_iterator lower_bound(const key_type& key) const { + return internal_end(internal_lower_bound(key, const_iterator(root(), 0))); + } + + // Finds the first element whose key is greater than key. + iterator upper_bound(const key_type& key) { + return internal_end(internal_upper_bound(key, iterator(root(), 0))); } + const_iterator upper_bound(const key_type& key) const { + return internal_end(internal_upper_bound(key, const_iterator(root(), 0))); } + + // 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). + std::pair equal_range(const key_type& key) { + return std::make_pair(lower_bound(key), upper_bound(key)); + } + std::pair equal_range(const key_type& key) const { + return std::make_pair(lower_bound(key), upper_bound(key)); + } + + // Inserts a value into the btree only if it does not already exist. The + // boolean return value indicates whether insertion succeeded or failed. + template + std::pair emplace_unique_key_args(const key_type& key, Args&&... args); + + template + std::pair emplace_unique(P&& x) { + return emplace_unique_extract_key(std::forward

(x), btree_can_extract_key()); + } + + template + typename std::enable_if< + btree_can_extract_map_key::value, + std::pair + >::type emplace_unique(First&& f, Second&& s) { + return emplace_unique_key_args(f, + std::forward(f), + std::forward(s)); + } + + // Inserts a value into the btree only if it does not already exist. The + // boolean return value indicates whether insertion succeeded or failed. + template + std::pair emplace_unique(Args&&... args) { + value_type v(std::forward(args)...); + return emplace_unique_key_args(params_type::get_key(v), std::move(v)); + } + + template + std::pair + emplace_unique_extract_key(P&& x, btree_extract_key_fail_tag) { + value_type v(std::forward

(x)); + return emplace_unique_key_args(params_type::get_key(v), std::move(v)); + } + + template + std::pair + emplace_unique_extract_key(P&& x, btree_extract_key_self_tag) { + return emplace_unique_key_args(x, std::forward

(x)); + } + + template + std::pair + emplace_unique_extract_key(P&& x, btree_extract_key_first_tag) { + return emplace_unique_key_args(x.first, std::forward

(x)); + } + + // Insert with hint. Check to see if the value should be placed immediately + // before position in the tree. If it does, then the insertion will take + // amortized constant time. If not, the insertion will take amortized + // logarithmic time as if a call to emplace_unique(v) were made. + template + iterator emplace_hint_unique_key_args(const_iterator hint, const key_type& key, Args&&... args); + + template + std::pair emplace_hint_unique(const_iterator hint, P&& x) { + return emplace_hint_unique_extract_key(hint, std::forward

(x), btree_can_extract_key()); + } + + template + typename std::enable_if< + btree_can_extract_map_key::value, + iterator + >::type emplace_hint_unique(const_iterator hint, First&& f, Second&& s) { + return emplace_hint_unique_key_args(hint, f, + std::forward(f), + std::forward(s)); + } + + // Inserts a value into the btree only if it does not already exist. The + // boolean return value indicates whether insertion succeeded or failed. + template + iterator emplace_hint_unique(const_iterator hint, Args&&... args) { + value_type v(std::forward(args)...); + return emplace_hint_unique_key_args(hint, params_type::get_key(v), std::move(v)); + } + + template + iterator + emplace_hint_unique_extract_key(const_iterator hint, P&& x, btree_extract_key_fail_tag) { + value_type v(std::forward

(x)); + return emplace_hint_unique_key_args(hint, params_type::get_key(v), std::move(v)); + } + + template + iterator + emplace_hint_unique_extract_key(const_iterator hint, P&& x, btree_extract_key_self_tag) { + return emplace_hint_unique_key_args(hint, x, std::forward

(x)); + } + + template + iterator + emplace_hint_unique_extract_key(const_iterator hint, P&& x, btree_extract_key_first_tag) { + return emplace_hint_unique_key_args(hint, x.first, std::forward

(x)); + } + + std::pair insert_unique(const value_type& v) { + return emplace_unique_key_args(params_type::get_key(v), v); + } + std::pair insert_unique(value_type&& v) { + return emplace_unique_key_args(params_type::get_key(v), std::move(v)); + } + iterator insert_unique(const_iterator hint, const value_type& v) { + return emplace_hint_unique_key_args(hint, params_type::get_key(v), v); + } + iterator insert_unique(const_iterator hint, value_type&& v) { + return emplace_hint_unique_key_args(hint, params_type::get_key(v), std::move(v)); + } + template ::type>::type, + value_type + >::value>::type> + std::pair insert_unique(P&& x) { + return emplace_unique(std::forward

(x)); + } + template ::type>::type, + value_type + >::value>::type> + iterator insert_unique(const_iterator hint, P&& x) { + return emplace_hint_unique(hint, std::forward

(x)); + } + + // Inserts a value into the btree. + template + iterator emplace_multi_key_args(const key_type& key, Args&&... args); + + // Inserts a value into the btree. + template + iterator emplace_multi(Args&&... args) { + value_type v(std::forward(args)...); + return emplace_multi_key_args(params_type::get_key(v), std::move(v)); + } + + // Insert with hint. Check to see if the value should be placed immediately + // before hint position in the tree. If it does, then the insertion will take + // amortized constant time. If not, the insertion will take amortized + // logarithmic time as if a call to emplace_multi(v) were made. + template + iterator emplace_hint_multi_key_args(const_iterator hint, const key_type& key, Args&&... args); + + // Inserts a value into the btree. + template + iterator emplace_hint_multi(const_iterator hint, Args&&... args) { + value_type v(std::forward(args)...); + return emplace_hint_multi_key_args(hint, params_type::get_key(v), std::move(v)); + } + + iterator insert_multi(const value_type& v) { + return emplace_multi_key_args(params_type::get_key(v), v); + } + iterator insert_multi(value_type&& v) { + return emplace_multi_key_args(params_type::get_key(v), std::move(v)); + } + iterator insert_multi(const_iterator hint, const value_type& v) { + return emplace_hint_multi_key_args(hint, params_type::get_key(v), v); + } + iterator insert_multi(const_iterator hint, value_type&& v) { + return emplace_hint_multi_key_args(hint, params_type::get_key(v), std::move(v)); + } + template ::type>::type, + value_type + >::value>::type> + iterator insert_multi(P&& x) { + return emplace_multi(std::forward

(x)); + } + template ::type>::type, + value_type + >::value>::type> + iterator insert_multi(const_iterator hint, P&& x) { + return emplace_hint_multi(hint, std::forward

(x)); + } + + void assign(const self_type& x); + + // Erase the specified iterator from the btree. The iterator must be valid + // (i.e. not equal to end()). Return an iterator pointing to the node after + // the one that was erased (or end() if none exists). + iterator erase(const_iterator iter); + + // Erases range. Returns the number of keys erased. + int erase(const_iterator begin, const_iterator end); + + // Erases the specified key from the btree. Returns 1 if an element was + // erased and 0 otherwise. + int erase_unique(const key_type& key); + + // Erases all of the entries matching the specified key from the + // btree. Returns the number of elements erased. + int erase_multi(const key_type& key); + + // Finds the iterator corresponding to a key or returns end() if the key is + // not present. + iterator find_unique(const key_type& key) { + return internal_end(internal_find_unique(key, iterator(root(), 0))); + } + const_iterator find_unique(const key_type& key) const { + return internal_end(internal_find_unique(key, const_iterator(root(), 0))); + } + iterator find_multi(const key_type& key) { + return internal_end(internal_find_multi(key, iterator(root(), 0))); + } + const_iterator find_multi(const key_type& key) const { + return internal_end(internal_find_multi(key, const_iterator(root(), 0))); + } + + // Returns a count of the number of times the key appears in the btree. + size_type count_unique(const key_type& key) const { + const_iterator begin = internal_find_unique(key, const_iterator(root(), 0)); + if (!begin.node) { + // 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. + size_type count_multi(const key_type& key) const { + return distance(lower_bound(key), upper_bound(key)); + } + + // Clear the btree, deleting all of the values it contains. + void clear(); + + // Swap the contents of* this and x. + void swap(self_type& x); + + // Assign the contents of x to* this. + self_type& operator=(const self_type& x) { + if (&x == this) { + // Don't copy onto ourselves. + return *this; + } + assign(x); + return *this; + } + + key_compare& __key_comp() { + return *this; + } + const key_compare& key_comp() const { + return *this; + } + bool compare_keys(const key_type& x, const key_type& y) const { + return btree_compare_keys(key_comp(), x, y); + } + + // Dump the btree to the specified ostream. Requires that operator<< is + // defined for Key and Value. + void dump(std::ostream& os) const { + if (root() != nullptr) { + internal_dump(os, root(), 0); + } + } + + // Verifies the structure of the btree. + void verify() const; + + // Size routines. Note that empty() is slightly faster than doing size()==0. + size_type size() const { + if (empty()) return 0; + if (root()->is_leaf()) return root()->count(); + return root()->size(); + } + + size_type max_size() const { + return std::numeric_limits::max(); + } + + bool empty() const { + return root() == nullptr; + } + + // The height of the btree. An empty tree will have height 0. + size_type height() const { + size_type h = 0; + if (root()) { + // Count the length of the chain from the leftmost node up to the + // root. We actually count from the root back around to the level below + // the root, but the calculation is the same because of the circularity + // of that traversal. + const node_type* n = root(); + do { + ++h; + n = n->get_parent(); + } while (n != root()); + } + return h; + } + + // The number of internal, leaf and total nodes used by the btree. + size_type leaf_nodes() const { + return internal_stats(root()).leaf_nodes; + } + size_type internal_nodes() const { + return internal_stats(root()).internal_nodes; + } + size_type nodes() const { + node_stats stats = internal_stats(root()); + return stats.leaf_nodes + stats.internal_nodes; + } + + // The total number of bytes used by the btree. + size_type bytes_used() const { + node_stats stats = internal_stats(root()); + if (stats.leaf_nodes == 1 && stats.internal_nodes == 0) { + return sizeof(*this) + + sizeof(base_fields) + root()->max_count() * sizeof(value_type); + } else { + return sizeof(*this) + + sizeof(root_fields) - sizeof(internal_fields) + + stats.leaf_nodes * sizeof(leaf_fields) + + stats.internal_nodes * sizeof(internal_fields); + } + } + + // The average number of bytes used per value stored in the btree. + static double average_bytes_per_value() { + // Returns the number of bytes per value on a leaf node that is 75% + // full. Experimentally, this matches up nicely with the computed number of + // bytes per value in trees that had their values inserted in random order. + return sizeof(leaf_fields) / (kNodeValues * 0.75); + } + + // The fullness of the btree. Computed as the number of elements in the btree + // divided by the maximum number of elements a tree with the current number + // of nodes could hold. A value of 1 indicates perfect space + // utilization. Smaller values indicate space wastage. + double fullness() const { + return double(size()) / (nodes() * kNodeValues); + } + // The overhead of the btree structure in bytes per node. Computed as the + // total number of bytes used by the btree minus the number of bytes used for + // storing elements divided by the number of elements. + double overhead() const { + if (empty()) { + return 0.0; + } + return (bytes_used() - size() * kValueSize) / double(size()); + } + +private: + // Internal accessor routines. + node_type* root() { + return root_.data; + } + const node_type* root() const { + return root_.data; + } + node_type*& __root() { + return root_.data; + } + + // The rightmost node is stored in the root node. + node_type* rightmost() { + return (!root() || root()->is_leaf()) ? root() : root()->rightmost(); + } + const node_type* rightmost() const { + return (!root() || root()->is_leaf()) ? root() : root()->rightmost(); + } + node_type*& __rightmost() { + return root()->__rightmost(); + } + + // The leftmost node is stored as the parent of the root node. + node_type* leftmost() { + return root() ? root()->get_parent() : nullptr; + } + const node_type* leftmost() const { + return root() ? root()->get_parent() : nullptr; + } + + // The size of the tree is stored in the root node. + size_type& __size() { + return root()->__size(); + } + + // Allocator routines. + internal_allocator_type& __internal_allocator() noexcept { + return *static_cast(&root_); + } + const internal_allocator_type& internal_allocator() const noexcept { + return *static_cast(&root_); + } + + allocator_type allocator() const noexcept { + return allocator_type(internal_allocator()); + } + + // Node creation/deletion routines. + node_type* new_internal_node(node_type* parent) { + internal_allocator_type& ia = __internal_allocator(); + internal_fields* p = reinterpret_cast(internal_allocator_traits::allocate(ia, sizeof(internal_fields))); + return node_type::init_internal(p, parent); + } + node_type* new_internal_root_node() { + internal_allocator_type& ia = __internal_allocator(); + root_fields* p = reinterpret_cast(internal_allocator_traits::allocate(ia, sizeof(root_fields))); + return node_type::init_root(p, root()->get_parent()); + } + node_type* new_leaf_node(node_type* parent) { + internal_allocator_type& ia = __internal_allocator(); + leaf_fields* p = reinterpret_cast(internal_allocator_traits::allocate(ia, sizeof(leaf_fields))); + return node_type::init_leaf(p, parent, kNodeValues); + } + node_type* new_leaf_root_node(int max_count) { + internal_allocator_type& ia = __internal_allocator(); + leaf_fields* p = reinterpret_cast(internal_allocator_traits::allocate(ia, sizeof(base_fields) + max_count * sizeof(value_type))); + return node_type::init_leaf(p, reinterpret_cast(p), max_count); + } + void delete_internal_node(node_type* node) { + node->destroy(); + assert(node != root()); + internal_allocator_type& ia = __internal_allocator(); + internal_allocator_traits::deallocate(ia, reinterpret_cast(node), sizeof(internal_fields)); + } + void delete_internal_root_node() { + root()->destroy(); + internal_allocator_type& ia = __internal_allocator(); + internal_allocator_traits::deallocate(ia, reinterpret_cast(root()), sizeof(root_fields)); + } + void delete_leaf_node(node_type* node) { + node->destroy(); + internal_allocator_type& ia = __internal_allocator(); + internal_allocator_traits::deallocate(ia, reinterpret_cast(node), sizeof(base_fields) + node->max_count() * sizeof(value_type)); + } + + // Rebalances or splits the node iter points to. + void rebalance_or_split(iterator& iter); + + // Merges the values of left, right and the delimiting key on their parent + // onto left, removing the delimiting key and deleting right. + void merge_nodes(node_type* left, node_type* right); + + // Tries to merge node with its left or right sibling, and failing that, + // rebalance with its left or right sibling. Returns true if a merge + // occurred, at which point it is no longer valid to access node. Returns + // false if no merging took place. + bool try_merge_or_rebalance(const_iterator& iter); + + // Tries to shrink the height of the tree by 1. + void try_shrink(); + + iterator internal_end(const_iterator iter) { + return iter.node ? iterator(iter.node, iter.position) : end(); + } + const_iterator internal_end(const_iterator iter) const { + return iter.node ? iter : end(); + } + + // Inserts a value into the btree immediately before iter. Requires that + // key(v) <= iter.key() and (--iter).key() <= key(v). + template + iterator internal_emplace(const_iterator hint, Args&&... args); + + // Returns an iterator pointing to the first value >= the value "iter" is + // pointing at. Note that "iter" might be pointing to an invalid location as + // iter.position == iter.node->count(). This routine simply moves iter up in + // the tree to a valid location. + template + 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 (internal_locate_plain_compare) always returns 0 for the second + // field of the pair. The second version (internal_locate_compare_to) is for + // the key-compare-to specialization and returns either kExactMatch (if the + // key was found in the tree) or -kExactMatch (if it wasn't) in the second + // field of the pair. The compare_to specialization allows the caller to + // avoid a subsequent comparison to determine if an exact match was made, + // speeding up string keys. + template + std::pair internal_locate(const key_type& key, IterType iter) const; + template + std::pair internal_locate_plain_compare(const key_type& key, IterType iter) const; + template + std::pair internal_locate_compare_to(const key_type& key, IterType iter) const; + + // Internal routine which implements lower_bound(). + template + IterType internal_lower_bound(const key_type& key, IterType iter) const; + + // Internal routine which implements upper_bound(). + template + IterType internal_upper_bound(const key_type& key, IterType iter) const; + + // Internal routine which implements find_unique(). + template + IterType internal_find_unique(const key_type& key, IterType iter) const; + + // Internal routine which implements find_multi(). + template + IterType internal_find_multi(const key_type& key, IterType iter) const; + + // Deletes a node and all of its children. + void internal_clear(node_type* node); + + // Dumps a node and all of its children to the specified ostream. + void internal_dump(std::ostream& os, const node_type* node, int level) const; + + // Verifies the tree structure of node. + int internal_verify(const node_type* node, const key_type* lo, const key_type* hi) const; + + node_stats internal_stats(const node_type* node) const { + if (!node) { + return node_stats(0, 0); + } + if (node->is_leaf()) { + return node_stats(1, 0); + } + node_stats res(0, 1); + for (int i = 0; i <= node->count(); ++i) { + res += internal_stats(node->child(i)); + } + return res; + } + +private: + empty_base_handle root_; + +private: + // A never instantiated helper function that returns big_ if we have a + // key-compare-to functor or if R is bool and small_ otherwise. + template + static std::conditional_t< + std::conditional_t, + std::is_same>::value, + big_, + small_> key_compare_checker(R); + + // A never instantiated helper function that returns the key comparison + // functor. + static key_compare key_compare_helper(); + + // Verify that key_compare returns a bool. This is similar to the way + // is_convertible in base/type_traits.h works. Note that key_compare_checker + // is never actually invoked. The compiler will select which + // key_compare_checker() to instantiate and then figure out the size of the + // return type of key_compare_checker() at compile time which we then check + // against the sizeof of big_. + COMPILE_ASSERT(sizeof(key_compare_checker(key_compare_helper()(key_type(), key_type()))) == sizeof(big_), + key_comparison_function_must_return_bool); + + // Note: We insist on kTargetValues, which is computed from + // Params::kTargetNodeSize, must fit the base_fields::field_type. + COMPILE_ASSERT((kNodeValues < (1 << (8 * sizeof(typename base_fields::field_type)))), + target_node_size_too_large); + + // Test the assumption made in setting kNodeValueSpace. + COMPILE_ASSERT(sizeof(base_fields) >= 2 * sizeof(void*), + node_space_assumption_incorrect); +}; + +//// +// btree_node methods +template template +inline void btree_node

::insert_value(int i, Args&&... args) { + auto cnt = count(); + + assert(i <= cnt); + + // Initialize new value at the end. + construct_value(cnt, std::forward(args)...); + + // Move initialized value to the correct position. + if (cnt > i) { + if (is_leaf()) { + for (int j = cnt; j > i; --j) { + swap_value(j - 1, j); + } + } else { + for (int j = cnt; j > i; --j) { + swap_value(j - 1, j); + move_child(j, j + 1); + } + } + } + + // Increase number of items + set_count(cnt + 1); +} + +template +inline void btree_node

::remove_value(int i) { + auto cnt = count(); + + // Move the value to the end. + if (is_leaf()) { + for (int j = i + 1; j < cnt; ++j) { + swap_value(j, j - 1); + } + } else { + assert(child(i + 1)->count() == 0); + for (int j = i + 1; j < cnt; ++j) { + swap_value(j, j - 1); + move_child(j + 1, j); + } + reset_child(cnt); + } + + // Decrease number of items. + set_count(--cnt); + + // Finally, destroy value. + destroy_value(cnt); +} + +template +void btree_node

::rebalance_right_to_left(btree_node* src, int to_move) { + auto cnt = count(); + auto src_cnt = src->count(); + + assert(get_parent() == src->get_parent()); + assert(position() + 1 == src->position()); + assert(src_cnt >= cnt); + assert(to_move >= 1); + assert(to_move <= src_cnt); + + // Move the delimiting value to the left node. + get_parent()->move_value(position(), this, cnt); + + // Move the new delimiting value from the right node. + src->move_value(to_move - 1, get_parent(), position()); + + if (is_leaf()) { + // Move the values from the right to the left node. + for (int i = 1; i < to_move; ++i) { + src->move_value(i - 1, this, cnt + i); + } + // Shift the values in the right node to their correct position. + for (int i = to_move; i < src_cnt; ++i) { + src->move_value(i, i - to_move); + } + } else { + // Move the values and child pointsts from the right to the left node. + src->move_child(0, this, 1 + cnt); + for (int i = 1; i < to_move; ++i) { + src->move_value(i - 1, this, cnt + i); + src->move_child(i, this, 1 + cnt + i); + } + // Shift the values and child pointsts in the right node to their correct position. + for (int i = to_move; i < src_cnt; ++i) { + src->move_value(i, i - to_move); + src->move_child(i, i - to_move); + } + src->move_child(src_cnt, src_cnt - to_move); + } + + // Fixup the counts on the src and dst nodes. + set_count(cnt + to_move); + src->set_count(src_cnt - to_move); +} + +template +void btree_node

::rebalance_left_to_right(btree_node* dst, int to_move) { + auto cnt = count(); + auto dst_cnt = dst->count(); + + assert(get_parent() == dst->get_parent()); + assert(position() + 1 == dst->position()); + assert(cnt >= dst_cnt); + assert(to_move >= 1); + assert(to_move <= cnt); + + // Make room in the right node for the new values. + for (int i = dst_cnt - 1; i >= 0; --i) { + dst->move_value(i, i + to_move); + } + + // Move the delimiting value to the right node. + get_parent()->move_value(position(), dst, to_move - 1); + + // Move the new delimiting value from the left node. + this->move_value(cnt - to_move, get_parent(), position()); + + if (is_leaf()) { + // Move the values from the left to the right node. + for (int i = 1; i < to_move; ++i) { + move_value(cnt - to_move + i, dst, i - 1); + } + } else { + // Move the values and child pointers from the left to the right node. + for (int i = dst_cnt; i >= 0; --i) { + dst->move_child(i, i + to_move); + } + // Move the values and child pointers from the left to the right node. + for (int i = 1; i < to_move; ++i) { + move_value(cnt - to_move + i, dst, i - 1); + move_child(cnt - to_move + i, dst, i - 1); + } + move_child(cnt, dst, to_move - 1); + } + + // Fixup the counts on the src and dst nodes. + set_count(cnt - to_move); + dst->set_count(dst_cnt + to_move); +} + +template +void btree_node

::split(btree_node* dst, int insert_position) { + auto cnt = count(); + auto dst_cnt = dst->count(); + + assert(dst_cnt == 0); + + // We bias the split based on the position being inserted. If we're + // inserting at the beginning of the left node then bias the split to put + // more values on the right node. If we're inserting at the end of the + // right node then bias the split to put more values on the left node. + if (insert_position == 0) { + dst_cnt = cnt - 1; + dst->set_count(dst_cnt); + } else if (insert_position != max_count()) { + dst_cnt = cnt / 2; + dst->set_count(dst_cnt); + } + assert(cnt > dst_cnt); + cnt -= dst_cnt; + set_count(cnt); + + if (is_leaf()) { + // Move values from the left sibling to the right sibling. + for (int i = 0; i < dst_cnt; ++i) { + move_value(cnt + i, dst, i); + } + } else { + // Move values and child pointers from the left sibling to the right sibling. + for (int i = 0; i < dst_cnt; ++i) { + move_value(cnt + i, dst, i); + move_child(cnt + i, dst, i); + } + move_child(cnt + dst_cnt, dst, dst_cnt); + } + + // The split key is the largest value in the left sibling. + set_count(--cnt); + get_parent()->insert_value(position(), std::move(value(cnt))); + destroy_value(cnt); + get_parent()->set_child(position() + 1, dst); +} + +template +void btree_node

::merge(btree_node* src) { + auto cnt = count(); + auto src_cnt = src->count(); + auto parent = get_parent(); + auto parent_cnt = parent->count(); + + assert(parent == src->get_parent()); + assert(position() + 1 == src->position()); + + // Move the delimiting value to the left node. + parent->move_value(position(), this, cnt); + + // Shift the values in the parent node to their correct position. + for (int i = position() + 1; i < parent_cnt; ++i) { + parent->move_value(i, i - 1); + parent->move_child(i + 1, i); + } + parent->reset_child(parent_cnt); + + if (is_leaf()) { + // Move the values from the right to the left node. + for (int i = 0; i < src_cnt; ++i) { + src->move_value(i, this, 1 + cnt + i); + } + } else { + // Move the values and child pointers from the right to the left node. + for (int i = 0; i < src_cnt; ++i) { + src->move_value(i, this, 1 + cnt + i); + src->move_child(i, this, 1 + cnt + i); + } + src->move_child(src_cnt, this, 1 + cnt + src_cnt); + } + + // Fixup the counts on the parent, src and dst nodes. + parent->set_count(parent_cnt - 1); + set_count(1 + cnt + src_cnt); + src->set_count(0); +} + +template +void btree_node

::swap(btree_node* x) { + auto cnt = count(); + auto x_cnt = x->count(); + + int min = std::min(cnt, x_cnt); + + assert(is_leaf() == x->is_leaf()); + + if (is_leaf()) { + // Swap the values. + for (int i = 0; i < min; ++i) { + swap_value(i, x); + } + for (int i = min; i < x_cnt; ++i) { + x->move_value(i, this); + } + for (int i = min; i < cnt; ++i) { + move_value(i, x); + } + } else { + // Swap the values and child pointers. + for (int i = 0; i < min; ++i) { + swap_value(i, x); + swap_child(i, x); + } + swap_child(min, x); + for (int i = min; i < x_cnt; ++i) { + x->move_value(i, this); + x->move_child(i + 1, this); + } + for (int i = min; i < cnt; ++i) { + move_value(i, x); + move_child(i + 1, x); + } + } + + // Swap the counts. + btree_swap_helper(fields_.count, x->fields_.count); +} + +//// +// btree_iterator methods +template +void btree_iterator::increment_slow() { + if (node->is_leaf()) { + assert(position >= node->count()); + self_type save(*this); + while (position == node->count() && !node->is_root()) { + assert(node->get_parent()->child(node->position()) == node); + position = node->position(); + node = node->get_parent(); + } + if (position == node->count()) { + *this = save; + } + } else { + assert(position < node->count()); + node = node->child(position + 1); + while (!node->is_leaf()) { + node = node->child(0); + } + position = 0; + } +} + +template +void btree_iterator::increment_by(int count) { + while (count > 0) { + if (node->is_leaf()) { + int rest = node->count() - position; + position += std::min(rest, count); + count = count - rest; + if (position < node->count()) { + return; + } + } else { + --count; + } + increment_slow(); + } +} + +template +void btree_iterator::decrement_slow() { + if (node->is_leaf()) { + assert(position <= -1); + self_type save(*this); + while (position < 0 && !node->is_root()) { + assert(node->get_parent()->child(node->position()) == node); + position = node->position() - 1; + node = node->get_parent(); + } + if (position < 0) { + *this = save; + } + } else { + assert(position >= 0); + node = node->child(position); + while (!node->is_leaf()) { + node = node->child(node->count()); + } + position = node->count() - 1; + } +} + +//// +// btree methods +template +btree

::btree(const key_compare& comp, const allocator_type& alloc) + : key_compare(comp), + root_(alloc, nullptr) { +} + +template +btree

::btree(const self_type& x) + : key_compare(x.key_comp()), + root_(x.internal_allocator(), nullptr) { + assign(x); +} + +template template +std::pair::iterator, bool> +btree

::emplace_unique_key_args(const key_type& key, Args&&... args) { + if (empty()) { + __root() = new_leaf_root_node(1); + } + + std::pair res = internal_locate(key, iterator(root(), 0)); + iterator& iter = res.first; + if (res.second == kExactMatch) { + // The key already exists in the tree, do nothing. + return std::make_pair(internal_last(iter), false); + } else if (!res.second) { + iterator last = internal_last(iter); + if (last.node && !compare_keys(key, last.key())) { + // The key already exists in the tree, do nothing. + return std::make_pair(last, false); + } + } + + return std::make_pair(internal_emplace(iter, std::forward(args)...), true); +} + +template template +inline typename btree

::iterator +btree

::emplace_hint_unique_key_args(const_iterator hint, const key_type& key, Args&&... args) { + if (!empty()) { + if (hint == end() || compare_keys(key, hint.key())) { + const_iterator prev = hint; + if (hint == begin() || compare_keys((--prev).key(), key)) { + // prev.key() < key < hint.key() + return internal_emplace(hint, std::forward(args)...); + } + } else if (compare_keys(hint.key(), key)) { + const_iterator next = hint; + ++next; + if (next == end() || compare_keys(key, next.key())) { + // hint.key() < key < next.key() + return internal_emplace(next, std::forward(args)...); + } + } else { + // hint.key() == key + return iterator(hint.node, hint.position); + } + } + return emplace_unique(std::forward(args)...).first; +} + +template template +typename btree

::iterator +btree

::emplace_multi_key_args(const key_type& key, Args&&... args) { + if (empty()) { + __root() = new_leaf_root_node(1); + } + + iterator iter = internal_upper_bound(key, iterator(root(), 0)); + if (!iter.node) { + iter = end(); + } + return internal_emplace(iter, std::forward(args)...); +} + +template template +typename btree

::iterator +btree

::emplace_hint_multi_key_args(const_iterator hint, const key_type& key, Args&&... args) { + if (!empty()) { + if (hint == end() || !compare_keys(hint.key(), key)) { + const_iterator prev = hint; + if (hint == begin() || !compare_keys(key, (--prev).key())) { + // prev.key() <= key <= hint.key() + return internal_emplace(hint, std::forward(args)...); + } + } else { + const_iterator next = hint; + ++next; + if (next == end() || !compare_keys(next.key(), key)) { + // hint.key() < key <= next.key() + return internal_emplace(next, std::forward(args)...); + } + } + } + return emplace_multi(std::forward(args)...); +} + +template +void btree

::assign(const self_type& x) { + clear(); + + __key_comp() = x.key_comp(); + __internal_allocator() = x.internal_allocator(); + + // Assignment can avoid key comparisons because we know the order of the + // values is the same order we'll store them in. + for (const_iterator iter = x.begin(); iter != x.end(); ++iter) { + if (empty()) { + emplace_multi(*iter); + } else { + // If the btree is not empty, we can just insert the new value at the end + // of the tree! + internal_emplace(end(), *iter); + } + } +} + +template +typename btree

::iterator btree

::erase(const_iterator iter) { + bool internal_delete = false; + if (!iter.node->is_leaf()) { + // Deletion of a value on an internal node. Swap the key with the largest + // value of our left child. This is easy, we just decrement iter. + const_iterator tmp_iter(iter--); + assert(iter.node->is_leaf()); + assert(!compare_keys(tmp_iter.key(), iter.key())); + iter.node->swap_value(iter.position, tmp_iter.node, tmp_iter.position); + internal_delete = true; + --__size(); + } else if (!root()->is_leaf()) { + --__size(); + } + + // Delete the key from the leaf. + iter.node->remove_value(iter.position); + + // We want to return the next value after the one we just erased. If we + // erased from an internal node (internal_delete == true), then the next + // value is ++(++iter). If we erased from a leaf node (internal_delete == + // false) then the next value is ++iter. Note that ++iter may point to an + // internal node and the value in the internal node may move to a leaf node + // (iter.node) when rebalancing is performed at the leaf level. + + // Merge/rebalance as we walk back up the tree. + iterator res(iter.node, iter.position); + for (;;) { + if (iter.node == root()) { + try_shrink(); + if (empty()) { + return end(); + } + break; + } + if (iter.node->count() >= kMinNodeValues) { + break; + } + bool merged = try_merge_or_rebalance(iter); + if (iter.node->is_leaf()) { + res = iterator(iter.node, iter.position); + } + if (!merged) { + break; + } + iter.node = iter.node->get_parent(); + } + + // Adjust our return value. If we're pointing at the end of a node, advance + // the iterator. + if (res.position == res.node->count()) { + res.position = res.node->count() - 1; + ++res; + } + // If we erased from an internal node, advance the iterator. + if (internal_delete) { + ++res; + } + return res; +} + +template +int btree

::erase(const_iterator begin, const_iterator end) { + int count = distance(begin, end); + for (int i = 0; i < count; i++) { + begin = erase(begin); + } + return count; +} + +template +int btree

::erase_unique(const key_type& key) { + iterator iter = internal_find_unique(key, iterator(root(), 0)); + if (!iter.node) { + // The key doesn't exist in the tree, return nothing done. + return 0; + } + erase(iter); + return 1; +} + +template +int btree

::erase_multi(const key_type& key) { + iterator begin = internal_lower_bound(key, iterator(root(), 0)); + if (!begin.node) { + // The key doesn't exist in the tree, return nothing done. + return 0; + } + // Delete all of the keys between begin and upper_bound(key). + iterator end = internal_end(internal_upper_bound(key, iterator(root(), 0))); + return erase(begin, end); +} + +template +void btree

::clear() { + if (root() != nullptr) { + internal_clear(root()); + } + __root() = nullptr; +} + +template +void btree

::swap(self_type& x) { + std::swap(static_cast(*this), static_cast(x)); + std::swap(root_, x.root_); +} + +template +void btree

::verify() const { + if (root() != nullptr) { + assert(size() == internal_verify(root(), nullptr, nullptr)); + assert(leftmost() == (++const_iterator(root(), -1)).node); + assert(rightmost() == (--const_iterator(root(), root()->count())).node); + assert(leftmost()->is_leaf()); + assert(rightmost()->is_leaf()); + } else { + assert(size() == 0); + assert(leftmost() == nullptr); + assert(rightmost() == nullptr); + } +} + +template +void btree

::rebalance_or_split(iterator& iter) { + node_type*& node = iter.node; + int& insert_position = iter.position; + assert(node->count() == node->max_count()); + + // First try to make room on the node by rebalancing. + node_type* parent = node->get_parent(); + if (node != root()) { + if (node->position() > 0) { + // Try rebalancing with our left sibling. + node_type* left = parent->child(node->position() - 1); + if (left->count() < left->max_count()) { + // We bias rebalancing based on the position being inserted. If we're + // inserting at the end of the right node then we bias rebalancing to + // fill up the left node. + int to_move = (left->max_count() - left->count()) / + (1 + (insert_position < left->max_count())); + to_move = std::max(1, to_move); + + if (((insert_position - to_move) >= 0) || + ((left->count() + to_move) < left->max_count())) { + left->rebalance_right_to_left(node, to_move); + + assert(node->max_count() - node->count() == to_move); + insert_position = insert_position - to_move; + if (insert_position < 0) { + insert_position = insert_position + left->count() + 1; + node = left; + } + + assert(node->count() < node->max_count()); + return; + } + } + } + + if (node->position() < parent->count()) { + // Try rebalancing with our right sibling. + node_type* right = parent->child(node->position() + 1); + if (right->count() < right->max_count()) { + // 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 = (right->max_count() - right->count()) / + (1 + (insert_position > 0)); + to_move = std::max(1, to_move); + + if ((insert_position <= (node->count() - to_move)) || + ((right->count() + to_move) < right->max_count())) { + node->rebalance_left_to_right(right, to_move); + + if (insert_position > node->count()) { + insert_position = insert_position - node->count() - 1; + node = right; + } + + assert(node->count() < node->max_count()); + return; + } + } + } + + // Rebalancing failed, make sure there is room on the parent node for a new + // value. + if (parent->count() == parent->max_count()) { + iterator parent_iter(node->get_parent(), node->position()); + rebalance_or_split(parent_iter); + } + } else { + // Rebalancing not possible because this is the root node. + if (root()->is_leaf()) { + // The root node is currently a leaf node: create a new root node and set + // the current root node as the child of the new root. + parent = new_internal_root_node(); + parent->set_child(0, root()); + __root() = parent; + assert(__rightmost() == parent->child(0)); + } else { + // The root node is an internal node. We do not want to create a new root + // node because the root node is special and holds the size of the tree + // and a pointer to the rightmost node. So we create a new internal node + // and move all of the items on the current root into the new node. + parent = new_internal_node(parent); + parent->set_child(0, parent); + parent->swap(root()); + node = parent; + } + } + + // Split the node. + node_type* split_node; + if (node->is_leaf()) { + split_node = new_leaf_node(parent); + node->split(split_node, insert_position); + if (rightmost() == node) { + __rightmost() = split_node; + } + } else { + split_node = new_internal_node(parent); + node->split(split_node, insert_position); + } + + if (insert_position > node->count()) { + insert_position = insert_position - node->count() - 1; + node = split_node; + } +} + +template +void btree

::merge_nodes(node_type* left, node_type* right) { + left->merge(right); + if (right->is_leaf()) { + if (rightmost() == right) { + __rightmost() = left; + } + delete_leaf_node(right); + } else { + delete_internal_node(right); + } +} + +template +bool btree

::try_merge_or_rebalance(const_iterator& iter) { + node_type* parent = iter.node->get_parent(); + if (iter.node->position() > 0) { + // Try merging with our left sibling. + node_type* left = parent->child(iter.node->position() - 1); + if ((1 + left->count() + iter.node->count()) <= left->max_count()) { + iter.position += 1 + left->count(); + merge_nodes(left, iter.node); + iter.node = left; + return true; + } + } + if (iter.node->position() < parent->count()) { + // Try merging with our right sibling. + node_type* right = parent->child(iter.node->position() + 1); + if ((1 + iter.node->count() + right->count()) <= right->max_count()) { + merge_nodes(iter.node, right); + return true; + } + // Try rebalancing with our right sibling. We don't perform rebalancing if + // we deleted the first element from iter.node and the node is not + // empty. This is a small optimization for the common pattern of deleting + // from the front of the tree. + if ((right->count() > kMinNodeValues) && ((iter.node->count() == 0) || (iter.position > 0))) { + int to_move = (right->count() - iter.node->count()) / 2; + to_move = std::min(to_move, right->count() - 1); + iter.node->rebalance_right_to_left(right, to_move); + return false; + } + } + if (iter.node->position() > 0) { + // Try rebalancing with our left sibling. We don't perform rebalancing if + // we deleted the last element from iter.node and the node is not + // empty. This is a small optimization for the common pattern of deleting + // from the back of the tree. + node_type* left = parent->child(iter.node->position() - 1); + if ((left->count() > kMinNodeValues) && ((iter.node->count() == 0) || (iter.position < iter.node->count()))) { + int to_move = (left->count() - iter.node->count()) / 2; + to_move = std::min(to_move, left->count() - 1); + left->rebalance_left_to_right(iter.node, to_move); + iter.position += to_move; + return false; + } + } + return false; +} + +template +void btree

::try_shrink() { + if (root()->count() > 0) { + return; + } + // Deleted the last item on the root node, shrink the height of the tree. + if (root()->is_leaf()) { + assert(size() == 0); + delete_leaf_node(root()); + __root() = nullptr; + } else { + node_type* child = root()->child(0); + if (child->is_leaf()) { + // The child is a leaf node so simply make it the root node in the tree. + child->make_root(); + delete_internal_root_node(); + __root() = child; + } else { + // The child is an internal node. We want to keep the existing root node + // so we move all of the values from the child node into the existing + // (empty) root node. + child->swap(root()); + delete_internal_node(child); + } + } +} + +template template +inline IterType btree

::internal_last(IterType iter) { + while (iter.node && iter.position == iter.node->count()) { + iter.position = iter.node->position(); + iter.node = iter.node->get_parent(); + if (iter.node->is_leaf()) { + iter.node = nullptr; + } + } + return iter; +} + +template template +inline typename btree

::iterator +btree

::internal_emplace(const_iterator hint, Args&&... args) { + iterator iter(hint.node, hint.position); + if (!iter.node->is_leaf()) { + // We can't insert on an internal node. Instead, we'll insert after the + // previous value which is guaranteed to be on a leaf node. + --iter; + ++iter.position; + } + if (iter.node->count() == iter.node->max_count()) { + // Make room in the leaf for the new item. + if (iter.node->max_count() < kNodeValues) { + // Insertion into the root where the root is smaller that the full node + // size. Simply grow the size of the root node. + assert(iter.node == root()); + iter.node = new_leaf_root_node(std::min(kNodeValues, 2 * iter.node->max_count())); + iter.node->swap(root()); + delete_leaf_node(root()); + __root() = iter.node; + } else { + rebalance_or_split(iter); + ++__size(); + } + } else if (!root()->is_leaf()) { + ++__size(); + } + iter.node->insert_value(iter.position, std::forward(args)...); + return iter; +} + +template template +inline std::pair btree

::internal_locate(const key_type& key, IterType iter) const { + return internal_locate_type::dispatch(key, *this, iter); +} + +template template +inline std::pair btree

::internal_locate_plain_compare(const key_type& key, IterType iter) const { + for (;;) { + iter.position = iter.node->lower_bound(key, key_comp()); + if (iter.node->is_leaf()) { + break; + } + iter.node = iter.node->child(iter.position); + } + return std::make_pair(iter, 0); +} + +template template +inline std::pair btree

::internal_locate_compare_to(const key_type& key, IterType iter) const { + for (;;) { + int res = iter.node->lower_bound(key, key_comp()); + iter.position = res& kMatchMask; + if (res& kExactMatch) { + return std::make_pair(iter, static_cast(kExactMatch)); + } + if (iter.node->is_leaf()) { + break; + } + iter.node = iter.node->child(iter.position); + } + return std::make_pair(iter, -kExactMatch); +} + +template template +IterType btree

::internal_lower_bound(const key_type& key, IterType iter) const { + if (iter.node) { + for (;;) { + iter.position = + iter.node->lower_bound(key, key_comp())& kMatchMask; + if (iter.node->is_leaf()) { + break; + } + iter.node = iter.node->child(iter.position); + } + iter = internal_last(iter); + } + return iter; +} + +template template +IterType btree

::internal_upper_bound(const key_type& key, IterType iter) const { + if (iter.node) { + for (;;) { + iter.position = iter.node->upper_bound(key, key_comp()); + if (iter.node->is_leaf()) { + break; + } + iter.node = iter.node->child(iter.position); + } + iter = internal_last(iter); + } + return iter; +} + +template template +IterType btree

::internal_find_unique(const key_type& key, IterType iter) const { + if (iter.node) { + std::pair res = internal_locate(key, iter); + if (res.second == kExactMatch) { + return res.first; + } + if (!res.second) { + iter = internal_last(res.first); + if (iter.node && !compare_keys(key, iter.key())) { + return iter; + } + } + } + return IterType(nullptr, 0); +} + +template template +IterType btree

::internal_find_multi(const key_type& key, IterType iter) const { + if (iter.node) { + iter = internal_lower_bound(key, iter); + if (iter.node) { + iter = internal_last(iter); + if (iter.node && !compare_keys(key, iter.key())) { + return iter; + } + } + } + return IterType(nullptr, 0); +} + +template +void btree

::internal_clear(node_type* node) { + if (!node->is_leaf()) { + for (int i = 0; i <= node->count(); ++i) { + internal_clear(node->child(i)); + } + if (node == root()) { + delete_internal_root_node(); + } else { + delete_internal_node(node); + } + } else { + delete_leaf_node(node); + } +} + +template +void btree

::internal_dump(std::ostream& os, const node_type* node, int level) const { + for (int i = 0; i < node->count(); ++i) { + if (!node->is_leaf()) { + internal_dump(os, node->child(i), level + 1); + } + for (int j = 0; j < level; ++j) { + os << " "; + } + os << node->key(i) << " [" << level << "]\n"; + } + if (!node->is_leaf()) { + internal_dump(os, node->child(node->count()), level + 1); + } +} + +template +int btree

::internal_verify(const node_type* node, const key_type* lo, const key_type* hi) const { + assert(node->count() > 0); + assert(node->count() <= node->max_count()); + if (lo) { + assert(!compare_keys(node->key(0), *lo)); + } + if (hi) { + assert(!compare_keys(*hi, node->key(node->count() - 1))); + } + for (int i = 1; i < node->count(); ++i) { + assert(!compare_keys(node->key(i), node->key(i - 1))); + } + int count = node->count(); + if (!node->is_leaf()) { + for (int i = 0; i <= node->count(); ++i) { + assert(node->child(i) != nullptr); + assert(node->child(i)->get_parent() == node); + assert(node->child(i)->position() == i); + count += internal_verify(node->child(i), + (i == 0) ? lo : &node->key(i - 1), + (i == node->count()) ? hi : &node->key(i)); + } + for (int i = node->count() + 1; i <= node->max_count(); ++i) { + assert(node->child(i) == nullptr); + } + } + return count; +} + +// A common base class for btree::set, map, btree_multiset and +// btree_multimap. +template +class btree_container { + typedef btree_container self_type; + +public: + typedef typename Tree::params_type params_type; + typedef typename Tree::key_type key_type; + typedef typename Tree::value_type value_type; + typedef typename Tree::key_compare key_compare; + typedef typename Tree::allocator_type allocator_type; + typedef typename Tree::pointer pointer; + typedef typename Tree::const_pointer const_pointer; + typedef typename Tree::reference reference; + typedef typename Tree::const_reference const_reference; + typedef typename Tree::size_type size_type; + typedef typename Tree::difference_type difference_type; + typedef typename Tree::iterator iterator; + typedef typename Tree::const_iterator const_iterator; + typedef typename Tree::reverse_iterator reverse_iterator; + typedef typename Tree::const_reverse_iterator const_reverse_iterator; + +public: + // Default constructor. + btree_container(const key_compare& comp, const allocator_type& alloc) + : __tree(comp, alloc) { + } + + // Copy constructor. + btree_container(const self_type& x) + : __tree(x.__tree) { + } + + // Iterator routines. + iterator begin() { + return __tree.begin(); + } + const_iterator begin() const { + return __tree.begin(); + } + const_iterator cbegin() const { + return __tree.cbegin(); + } + iterator end() { + return __tree.end(); + } + const_iterator end() const { + return __tree.end(); + } + const_iterator cend() const { + return __tree.cend(); + } + reverse_iterator rbegin() { + return __tree.rbegin(); + } + const_reverse_iterator rbegin() const { + return __tree.rbegin(); + } + const_reverse_iterator crbegin() const { + return __tree.crbegin(); + } + reverse_iterator rend() { + return __tree.rend(); + } + const_reverse_iterator rend() const { + return __tree.rend(); + } + const_reverse_iterator crend() const { + return __tree.crend(); + } + + // Lookup routines. + iterator lower_bound(const key_type& key) { + return __tree.lower_bound(key); + } + const_iterator lower_bound(const key_type& key) const { + return __tree.lower_bound(key); + } + iterator upper_bound(const key_type& key) { + return __tree.upper_bound(key); + } + const_iterator upper_bound(const key_type& key) const { + return __tree.upper_bound(key); + } + std::pair equal_range(const key_type& key) { + return __tree.equal_range(key); + } + std::pair equal_range(const key_type& key) const { + return __tree.equal_range(key); + } + + allocator_type get_allocator() const noexcept { + return allocator_type(__tree.allocator()); + } + + // Utility routines. + void clear() { + __tree.clear(); + } + void swap(self_type& x) { + __tree.swap(x.__tree); + } + void dump(std::ostream& os) const { + __tree.dump(os); + } + void verify() const { + __tree.verify(); + } + + // Size routines. + size_type size() const { + return __tree.size(); + } + size_type max_size() const { + return __tree.max_size(); + } + bool empty() const { + return __tree.empty(); + } + + size_type height() const { + return __tree.height(); + } + size_type internal_nodes() const { + return __tree.internal_nodes(); + } + size_type leaf_nodes() const { + return __tree.leaf_nodes(); + } + size_type nodes() const { + return __tree.nodes(); + } + size_type bytes_used() const { + return __tree.bytes_used(); + } + static double average_bytes_per_value() { + return Tree::average_bytes_per_value(); + } + double fullness() const { + return __tree.fullness(); + } + double overhead() const { + return __tree.overhead(); + } + + bool operator==(const self_type& x) const { + if (size() != x.size()) { + return false; + } + for (const_iterator i = begin(), xi = x.begin(); i != end(); ++i, ++xi) { + if (*i !=* xi) { + return false; + } + } + return true; + } + + bool operator!=(const self_type& other) const { + return !operator==(other); + } + + + protected: + Tree __tree; +}; + +template +inline std::ostream& operator<<(std::ostream& os, const btree_container& b) { + b.dump(os); + return os; +} + +// A common base class for btree::map and btree::set. +template +class btree_unique_container : public btree_container { + typedef btree_unique_container self_type; + typedef btree_container super_type; + +public: + typedef typename Tree::key_type key_type; + typedef typename Tree::value_type value_type; + typedef typename Tree::size_type size_type; + typedef typename Tree::key_compare key_compare; + typedef typename Tree::allocator_type allocator_type; + typedef typename Tree::iterator iterator; + typedef typename Tree::const_iterator const_iterator; + +public: + // Default constructor. + btree_unique_container(const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + } + + // Copy constructor. + btree_unique_container(const self_type& x) + : super_type(x) { + } + + // Range constructor. + template + btree_unique_container(InputIterator b, InputIterator e, + const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + insert(b, e); + } + + // Lookup routines. + iterator find(const key_type& key) { + return this->__tree.find_unique(key); + } + const_iterator find(const key_type& key) const { + return this->__tree.find_unique(key); + } + size_type count(const key_type& key) const { + return this->__tree.count_unique(key); + } + + // Insertion routines. + std::pair insert(const value_type& x) { + return this->__tree.insert_unique(x); + } + template + std::pair insert(P&& x) { + return this->__tree.insert_unique(std::forward

(x)); + } + std::pair insert(value_type&& x) { + return this->__tree.insert_unique(std::move(x)); + } + iterator insert(const_iterator hint, const value_type& x) { + return this->__tree.insert_unique(hint, x); + } + template + std::pair insert(const_iterator hint, P&& x) { + return this->__tree.insert_unique(hint, std::forward

(x)); + } + iterator insert(const_iterator hint, value_type&& x) { + return this->__tree.insert_unique(hint, std::move(x)); + } + void insert(std::initializer_list il) { + insert(il.begin(), il.end()); + } + template + void insert(InputIterator f, InputIterator l) { + for (const_iterator end = this->cend(); f != l; ++f) { + insert(end, *f); + } + } + + template + std::pair emplace(Args&&... args) { + return this->__tree.emplace_unique(std::forward(args)...); + } + + template + iterator emplace_hint(const_iterator hint, Args&&... args) { + return this->__tree.emplace_hint_unique(hint, std::forward(args)...); + } + + // Deletion routines. + int erase(const key_type& key) { + return this->__tree.erase_unique(key); + } + // Erase the specified iterator from the btree. The iterator must be valid + // (i.e. not equal to end()). Return an iterator pointing to the node after + // the one that was erased (or end() if none exists). + iterator erase(const iterator& iter) { + return this->__tree.erase(iter); + } + void erase(const iterator& first, const iterator& last) { + this->__tree.erase(first, last); + } +}; + +// A common base class for btree::multimap and btree::multiset. +template +class btree_multi_container : public btree_container { + typedef btree_multi_container self_type; + typedef btree_container super_type; + + public: + typedef typename Tree::key_type key_type; + typedef typename Tree::value_type value_type; + typedef typename Tree::size_type size_type; + typedef typename Tree::key_compare key_compare; + typedef typename Tree::allocator_type allocator_type; + typedef typename Tree::iterator iterator; + typedef typename Tree::const_iterator const_iterator; + + public: + // Default constructor. + btree_multi_container(const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + } + + // Copy constructor. + btree_multi_container(const self_type& x) + : super_type(x) { + } + + // Range constructor. + template + btree_multi_container(InputIterator b, InputIterator e, + const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + insert(b, e); + } + + // Lookup routines. + iterator find(const key_type& key) { + return this->__tree.find_multi(key); + } + const_iterator find(const key_type& key) const { + return this->__tree.find_multi(key); + } + size_type count(const key_type& key) const { + return this->__tree.count_multi(key); + } + + // Insertion routines. + iterator insert(const value_type& x) { + return this->__tree.insert_multi(x); + } + template + iterator insert(P&& x) { + return this->__tree.insert_multi(std::forward

(x)); + } + iterator insert(value_type&& x) { + return this->__tree.insert_multi(std::move(x)); + } + iterator insert(const_iterator hint, const value_type& x) { + return this->__tree.insert_multi(hint, x); + } + template + iterator insert(const_iterator hint, P&& x) { + return this->__tree.insert_multi(hint, std::forward

(x)); + } + iterator insert(const_iterator hint, value_type&& x) { + return this->__tree.insert_multi(hint, std::move(x)); + } + template + void insert(InputIterator f, InputIterator l) { + for (const_iterator end = this->cend(); f != l; ++f) { + insert(end, *f); + } + } + void insert(std::initializer_list il) { + insert(il.begin(), il.end()); + } + + template + std::pair emplace(Args&&... args) { + return this->__tree.emplace_multi(std::forward(args)...); + } + + template + iterator emplace_hint(const_iterator hint, Args&&... args) { + return this->__tree.emplace_hint_multi(hint, std::forward(args)...); + } + + // Deletion routines. + int erase(const key_type& key) { + return this->__tree.erase_multi(key); + } + // Erase the specified iterator from the btree. The iterator must be valid + // (i.e. not equal to end()). Return an iterator pointing to the node after + // the one that was erased (or end() if none exists). + iterator erase(const iterator& iter) { + return this->__tree.erase(iter); + } + void erase(const iterator& first, const iterator& last) { + this->__tree.erase(first, last); + } +}; + +} // namespace btree + +#endif // BTREE_BTREE_H__ diff --git a/btree/map.h b/btree/map.h new file mode 100644 index 0000000..269063d --- /dev/null +++ b/btree/map.h @@ -0,0 +1,280 @@ +/* + * Copyright (c) 2019 German Mendez Bravo (Kronuz) + * Copyright (c) 2013 Google Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * + * A btree::map<> implements the STL unique sorted associative container + * interface and the pair associative container interface (a.k.a map<>) using a + * btree. See btree.h for details of the btree implementation and caveats. + */ + +#ifndef BTREE_MAP_H__ +#define BTREE_MAP_H__ + +#include "btree.h" + +#include + +namespace btree { + +// A common base class for map and safe_map. +template +class btree_map_container : public btree_unique_container { + typedef btree_map_container self_type; + typedef btree_unique_container super_type; + +public: + typedef typename Tree::key_type key_type; + typedef typename Tree::data_type data_type; + typedef typename Tree::value_type value_type; + typedef typename Tree::mapped_type mapped_type; + typedef typename Tree::key_compare key_compare; + typedef typename Tree::allocator_type allocator_type; + typedef typename Tree::iterator iterator; + typedef typename Tree::const_iterator const_iterator; + +public: + // Default constructor. + btree_map_container(const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + } + + // Copy constructor. + btree_map_container(const self_type& x) + : super_type(x) { + } + + // Range constructor. + template + btree_map_container(InputIterator b, InputIterator e, + const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(b, e, comp, alloc) { + } + + template + std::pair try_emplace(const key_type& key, Args&&... args) { + return this->__tree.emplace_unique_key_args(key, + std::piecewise_construct, + std::forward_as_tuple(key), + std::forward_as_tuple(std::forward(args)...)); + } + + template + std::pair try_emplace(key_type&& key, Args&&... args) { + return this->__tree.emplace_unique_key_args(key, + std::piecewise_construct, + std::forward_as_tuple(std::move(key)), + std::forward_as_tuple(std::forward(args)...)); + } + + template + iterator try_emplace(const_iterator hint, const key_type& key, Args&&... args) { + return this->__tree.emplace_hint_unique_key_args(hint, key, + std::piecewise_construct, + std::forward_as_tuple(key), + std::forward_as_tuple(std::forward(args)...)); + } + + template + iterator try_emplace(const_iterator hint, key_type&& key, Args&&... args) { + return this->__tree.emplace_hint_unique_key_args(hint, key, + std::piecewise_construct, + std::forward_as_tuple(std::move(key)), + std::forward_as_tuple(std::forward(args)...)); + } + + // Access specified element with bounds checking. + mapped_type& at(const key_type& key) { + auto it = this->find(key); + if (it == this->end()) { + throw std::out_of_range("map::at: key not found"); + } + return it->second; + } + const mapped_type& at(const key_type& key) const { + auto it = this->find(key); + if (it == this->end()) { + throw std::out_of_range("map::at: key not found"); + } + return it->second; + } + + // Insertion routines. + data_type& operator[](const key_type& key) { + return this->try_emplace(key).first->second; + } + + data_type& operator[](key_type&& key) { + return this->try_emplace(std::move(key)).first->second; + } +}; + +// The map class is needed mainly for its constructors. +template , + typename Alloc = std::allocator>, + int TargetNodeSize = 256> +class map : public btree_map_container< + btree>> { + + typedef map self_type; + typedef btree_map_params params_type; + typedef btree btree_type; + typedef btree_map_container super_type; + +public: + typedef typename btree_type::key_compare key_compare; + typedef typename btree_type::allocator_type allocator_type; + +public: + // Default constructor. + map(const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + } + + // Copy constructor. + map(const self_type& x) + : super_type(x) { + } + + // Range constructor. + template + map(InputIterator b, InputIterator e, + const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(b, e, comp, alloc) { + } +}; + +} // namespace btree + +template +bool operator==(const btree::map& lhs, const btree::map& rhs) { + return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin()); +} + +template +bool operator<(const btree::map& lhs, const btree::map& rhs) { + return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end()); +} + +template +bool operator!=(const btree::map& lhs, const btree::map& rhs) { + return !(lhs == rhs); +} + +template +bool operator>(const btree::map& lhs, const btree::map& rhs) { + return rhs < lhs; +} + +template +bool operator>=(const btree::map& lhs, const btree::map& rhs) { + return !(lhs < rhs); +} + +template +bool operator<=(const btree::map& lhs, const btree::map& rhs) { + return !(rhs < lhs); +} + +template +inline void swap(btree::map& x, btree::map& y) { + x.swap(y); +} + +namespace btree { + +// The multimap class is needed mainly for its constructors. +template , + typename Alloc = std::allocator >, + int TargetNodeSize = 256> +class multimap : public btree_multi_container< + btree > > { + + typedef multimap self_type; + typedef btree_map_params< Key, Value, Compare, Alloc, TargetNodeSize> params_type; + typedef btree btree_type; + typedef btree_multi_container super_type; + + public: + typedef typename btree_type::key_compare key_compare; + typedef typename btree_type::allocator_type allocator_type; + typedef typename btree_type::data_type data_type; + typedef typename btree_type::mapped_type mapped_type; + + public: + // Default constructor. + multimap(const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + } + + // Copy constructor. + multimap(const self_type& x) + : super_type(x) { + } + + // Range constructor. + template + multimap(InputIterator b, InputIterator e, + const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(b, e, comp, alloc) { + } +}; + +} // namespace btree + +template +bool operator==(const btree::multimap& lhs, const btree::multimap& rhs) { + return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin()); +} + +template +bool operator<(const btree::multimap& lhs, const btree::multimap& rhs) { + return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end()); +} + +template +bool operator!=(const btree::multimap& lhs, const btree::multimap& rhs) { + return !(lhs == rhs); +} + +template +bool operator>(const btree::multimap& lhs, const btree::multimap& rhs) { + return rhs < lhs; +} + +template +bool operator>=(const btree::multimap& lhs, const btree::multimap& rhs) { + return !(lhs < rhs); +} + +template +bool operator<=(const btree::multimap& lhs, const btree::multimap& rhs) { + return !(rhs < lhs); +} + +template +inline void swap(btree::multimap& x, btree::multimap& y) { + x.swap(y); +} + +#endif // BTREE_MAP_H__ diff --git a/btree/set.h b/btree/set.h new file mode 100644 index 0000000..4f5c344 --- /dev/null +++ b/btree/set.h @@ -0,0 +1,183 @@ +/* + * Copyright (c) 2019 German Mendez Bravo (Kronuz) + * Copyright (c) 2013 Google Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * + * A btree::set<> implements the STL unique sorted associative container + * interface (a.k.a set<>) using a btree. See btree.h for details of the btree + * implementation and caveats. + */ + +#ifndef BTREE_SET_H__ +#define BTREE_SET_H__ + +#include "btree.h" + +namespace btree { + +// The set class is needed mainly for its constructors. +template , + typename Alloc = std::allocator, + int TargetNodeSize = 256> +class set : public btree_unique_container< + btree > > { + + typedef set self_type; + typedef btree_set_params params_type; + typedef btree btree_type; + typedef btree_unique_container super_type; + + public: + typedef typename btree_type::key_compare key_compare; + typedef typename btree_type::allocator_type allocator_type; + + public: + // Default constructor. + set(const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + } + + // Copy constructor. + set(const self_type& x) + : super_type(x) { + } + + // Range constructor. + template + set(InputIterator b, InputIterator e, + const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(b, e, comp, alloc) { + } +}; + +} // namespace btree + +template +bool operator==(const btree::set& lhs, const btree::set& rhs) { + return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin()); +} + +template +bool operator<(const btree::set& lhs, const btree::set& rhs) { + return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end()); +} + +template +bool operator!=(const btree::set& lhs, const btree::set& rhs) { + return !(lhs == rhs); +} + +template +bool operator>(const btree::set& lhs, const btree::set& rhs) { + return rhs < lhs; +} + +template +bool operator>=(const btree::set& lhs, const btree::set& rhs) { + return !(lhs < rhs); +} + +template +bool operator<=(const btree::set& lhs, const btree::set& rhs) { + return !(rhs < lhs); +} + +template +inline void swap(btree::set& x, btree::set& y) { + x.swap(y); +} + +namespace btree { + +// The multiset class is needed mainly for its constructors. +template , + typename Alloc = std::allocator, + int TargetNodeSize = 256> +class multiset : public btree_multi_container< + btree > > { + + typedef multiset self_type; + typedef btree_set_params params_type; + typedef btree btree_type; + typedef btree_multi_container super_type; + + public: + typedef typename btree_type::key_compare key_compare; + typedef typename btree_type::allocator_type allocator_type; + + public: + // Default constructor. + multiset(const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(comp, alloc) { + } + + // Copy constructor. + multiset(const self_type& x) + : super_type(x) { + } + + // Range constructor. + template + multiset(InputIterator b, InputIterator e, + const key_compare& comp = key_compare(), + const allocator_type& alloc = allocator_type()) + : super_type(b, e, comp, alloc) { + } +}; + + +} // namespace btree + +template +bool operator==(const btree::multiset& lhs, const btree::multiset& rhs) { + return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin()); +} + +template +bool operator<(const btree::multiset& lhs, const btree::multiset& rhs) { + return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end()); +} + +template +bool operator!=(const btree::multiset& lhs, const btree::multiset& rhs) { + return !(lhs == rhs); +} + +template +bool operator>(const btree::multiset& lhs, const btree::multiset& rhs) { + return rhs < lhs; +} + +template +bool operator>=(const btree::multiset& lhs, const btree::multiset& rhs) { + return !(lhs < rhs); +} + +template +bool operator<=(const btree::multiset& lhs, const btree::multiset& rhs) { + return !(rhs < lhs); +} + +template +inline void swap(btree::multiset& x, btree::multiset& y) { + x.swap(y); +} + +#endif // BTREE_SET_H__