+++ /dev/null
-// Copyright 2013 Google Inc. All Rights Reserved.
-//
-// 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<int32> 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<int32> may use much
-// less memory per stored value. For the random insertion benchmark in
-// btree_test.cc, a btree_set<int32> 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) @ <size>
-// --------------------------------------------------------
-// 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 UTIL_BTREE_BTREE_H__
-#define UTIL_BTREE_BTREE_H__
-
-#include <assert.h>
-#include <stddef.h>
-#include <string.h>
-#include <sys/types.h>
-#include <algorithm>
-#include <functional>
-#include <iostream>
-#include <iterator>
-#include <limits>
-#include <type_traits>
-#include <new>
-#include <ostream>
-#include <string>
-#include <utility>
-
-#ifndef NDEBUG
-#define NDEBUG 1
-#endif
-
-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 <typename T>
-inline void btree_swap_helper(T &a, T &b) {
- using std::swap;
- swap(a, b);
-}
-
-// A template helper used to select A or B based on a condition.
-template<bool cond, typename A, typename B>
-struct if_{
- typedef A type;
-};
-
-template<typename A, typename B>
-struct if_<false, A, B> {
- typedef B type;
-};
-
-// Types small_ and big_ are promise that sizeof(small_) < sizeof(big_)
-typedef char small_;
-
-struct big_ {
- char dummy[2];
-};
-
-// A compile-time assertion.
-template <bool>
-struct CompileAssert {
-};
-
-#define COMPILE_ASSERT(expr, msg) \
- typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
-
-// 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 <typename Compare>
-struct btree_is_key_compare_to
- : public std::is_convertible<Compare, btree_key_compare_to_tag> {
-};
-
-// 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<string> and greater<string>. 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 <typename Compare>
-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<Compare> &c)
- : Compare(c) {
- }
-};
-
-template <>
-struct btree_key_compare_to_adapter<std::less<std::string> >
- : public btree_key_compare_to_tag {
- btree_key_compare_to_adapter() {}
- btree_key_compare_to_adapter(const std::less<std::string>&) {}
- btree_key_compare_to_adapter(
- const btree_key_compare_to_adapter<std::less<std::string> >&) {}
- int operator()(const std::string &a, const std::string &b) const {
- return a.compare(b);
- }
-};
-
-template <>
-struct btree_key_compare_to_adapter<std::greater<std::string> >
- : public btree_key_compare_to_tag {
- btree_key_compare_to_adapter() {}
- btree_key_compare_to_adapter(const std::greater<std::string>&) {}
- btree_key_compare_to_adapter(
- const btree_key_compare_to_adapter<std::greater<std::string> >&) {}
- 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 <typename Key, typename Compare, bool HaveCompareTo>
-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 <typename Key, typename Compare>
-struct btree_key_comparer<Key, Compare, true> {
- 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 <typename Key, typename Compare>
-static bool btree_compare_keys(
- const Compare &comp, const Key &x, const Key &y) {
- typedef btree_key_comparer<Key, Compare,
- btree_is_key_compare_to<Compare>::value> key_comparer;
- return key_comparer::bool_compare(comp, x, y);
-}
-
-template <typename Key, typename Compare,
- typename Alloc, int TargetNodeSize, int ValueSize>
-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 typename if_<
- btree_is_key_compare_to<Compare>::value,
- Compare, btree_key_compare_to_adapter<Compare> >::type 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<key_compare> is_key_compare_to;
-
- typedef Alloc allocator_type;
- typedef Key key_type;
- typedef ssize_t size_type;
- typedef ptrdiff_t difference_type;
-
- 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 typename if_<
- (kNodeValueSpace / ValueSize) >= 256,
- uint16_t,
- uint8_t>::type node_count_type;
-};
-
-// A parameters structure for holding the type parameters for a btree_map.
-template <typename Key, typename Data, typename Compare,
- typename Alloc, int TargetNodeSize>
-struct btree_map_params
- : public btree_common_params<Key, Compare, Alloc, TargetNodeSize,
- sizeof(Key) + sizeof(Data)> {
- typedef Data data_type;
- typedef Data mapped_type;
- typedef std::pair<const Key, data_type> value_type;
- typedef std::pair<Key, data_type> mutable_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 const Key& key(const value_type &x) { return x.first; }
- static const Key& key(const mutable_value_type &x) { return x.first; }
- static void swap(mutable_value_type *a, mutable_value_type *b) {
- btree_swap_helper(a->first, b->first);
- btree_swap_helper(a->second, b->second);
- }
-};
-
-// A parameters structure for holding the type parameters for a btree_set.
-template <typename Key, typename Compare, typename Alloc, int TargetNodeSize>
-struct btree_set_params
- : public btree_common_params<Key, Compare, Alloc, TargetNodeSize,
- sizeof(Key)> {
- typedef std::false_type data_type;
- typedef std::false_type mapped_type;
- typedef Key value_type;
- typedef value_type mutable_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 const Key& key(const value_type &x) { return x; }
- static void swap(mutable_value_type *a, mutable_value_type *b) {
- btree_swap_helper<mutable_value_type>(*a, *b);
- }
-};
-
-// An adapter class that converts a lower-bound compare into an upper-bound
-// compare.
-template <typename Key, typename Compare>
-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<const Compare&>(*this)(b, a);
- }
-};
-
-template <typename Key, typename CompareTo>
-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<const CompareTo&>(*this)(b, a);
- }
-};
-
-// Dispatch helper class for using linear search with plain compare.
-template <typename K, typename N, typename Compare>
-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<K, Compare> 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 <typename K, typename N, typename CompareTo>
-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<K,
- btree_key_comparer<K, CompareTo, true> > 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 <typename K, typename N, typename Compare>
-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<K, Compare> 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 <typename K, typename N, typename CompareTo>
-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<K,
- btree_key_comparer<K, CompareTo, true> > 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 <typename Params>
-class btree_node {
- public:
- typedef Params params_type;
- typedef btree_node<Params> 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::mutable_value_type mutable_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;
- // Typedefs for the various types of node searches.
- typedef btree_linear_search_plain_compare<
- key_type, self_type, key_compare> linear_search_plain_compare_type;
- typedef btree_linear_search_compare_to<
- key_type, self_type, key_compare> linear_search_compare_to_type;
- typedef btree_binary_search_plain_compare<
- key_type, self_type, key_compare> binary_search_plain_compare_type;
- typedef btree_binary_search_compare_to<
- key_type, self_type, key_compare> 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 typename if_<
- Params::is_key_compare_to::value,
- linear_search_compare_to_type,
- linear_search_plain_compare_type>::type linear_search_type;
- // If we have a valid key-compare-to type, use binary_search_compare_to,
- // otherwise use binary_search_plain_compare.
- typedef typename if_<
- Params::is_key_compare_to::value,
- binary_search_compare_to_type,
- binary_search_plain_compare_type>::type 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 typename if_<
- std::is_integral<key_type>::value ||
- std::is_floating_point<key_type>::value,
- linear_search_type, binary_search_type>::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.
- mutable_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 leaf() const { return fields_.leaf; }
-
- // Getter for the position of this node in its parent.
- int position() const { return fields_.position; }
- void set_position(int v) { fields_.position = v; }
-
- // Getter/setter for the number of values stored in this node.
- int count() const { return fields_.count; }
- void set_count(int v) { fields_.count = v; }
- int max_count() const { return fields_.max_count; }
-
- // Getter for the parent of this node.
- btree_node* 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 parent()->leaf(); }
- void make_root() {
- assert(parent()->is_root());
- fields_.parent = fields_.parent->parent();
- }
-
- // Getter for the rightmost root node field. Only valid on the root node.
- btree_node* rightmost() const { return fields_.rightmost; }
- btree_node** mutable_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* mutable_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::key(fields_.values[i]);
- }
- reference value(int i) {
- return reinterpret_cast<reference>(fields_.values[i]);
- }
- const_reference value(int i) const {
- return reinterpret_cast<const_reference>(fields_.values[i]);
- }
- mutable_value_type* mutable_value(int i) {
- return &fields_.values[i];
- }
-
- // Swap value i in this node with value j in node x.
- void value_swap(int i, btree_node *x, int j) {
- params_type::swap(mutable_value(i), x->mutable_value(j));
- }
-
- // Getters/setter for the child at position i in the node.
- btree_node* child(int i) const { return fields_.children[i]; }
- btree_node** mutable_child(int i) { return &fields_.children[i]; }
- void set_child(int i, btree_node *c) {
- *mutable_child(i) = c;
- c->fields_.parent = this;
- c->fields_.position = i;
- }
-
- // Returns the position of the first value whose key is not less than k.
- template <typename Compare>
- 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 <typename Compare>
- 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 <typename Compare>
- 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 <typename Compare>
- 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 <typename Compare>
- 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 <typename CompareTo>
- 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.
- void insert_value(int i, const value_type &x);
-
- // 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<btree_node*>(f);
- f->leaf = 1;
- f->position = 0;
- f->max_count = max_count;
- f->count = 0;
- f->parent = parent;
- if (!NDEBUG) {
- 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;
- if (!NDEBUG) {
- 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) {
- value_destroy(i);
- }
- }
-
- private:
- void value_init(int i) {
- new (&fields_.values[i]) mutable_value_type;
- }
- void value_init(int i, const value_type &x) {
- new (&fields_.values[i]) mutable_value_type(x);
- }
- void value_destroy(int i) {
- fields_.values[i].~mutable_value_type();
- }
-
- private:
- root_fields fields_;
-
- private:
- btree_node(const btree_node&);
- void operator=(const btree_node&);
-};
-
-template <typename Node, typename Reference, typename Pointer>
-struct btree_iterator {
- 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<Node>::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<
- normal_node, normal_reference, normal_pointer> iterator;
- typedef btree_iterator<
- const_node, const_reference, const_pointer> const_iterator;
- typedef btree_iterator<Node, Reference, Pointer> self_type;
-
- btree_iterator()
- : node(NULL),
- position(-1) {
- }
- btree_iterator(Node *n, int p)
- : node(n),
- position(p) {
- }
- btree_iterator(const iterator &x)
- : node(x.node),
- position(x.position) {
- }
-
- // Increment/decrement the iterator.
- void increment() {
- if (node->leaf() && ++position < node->count()) {
- return;
- }
- increment_slow();
- }
- void increment_by(int count);
- void increment_slow();
-
- void decrement() {
- if (node->leaf() && --position >= 0) {
- return;
- }
- decrement_slow();
- }
- void decrement_slow();
-
- 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;
- }
-
- // The node in the tree the iterator is pointing at.
- Node *node;
- // The position within the node of the tree the iterator is pointing at.
- int position;
-};
-
-// Dispatch helper class for using btree::internal_locate with plain compare.
-struct btree_internal_locate_plain_compare {
- template <typename K, typename T, typename Iter>
- static std::pair<Iter, int> 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 <typename K, typename T, typename Iter>
- static std::pair<Iter, int> dispatch(const K &k, const T &t, Iter iter) {
- return t.internal_locate_compare_to(k, iter);
- }
-};
-
-template <typename Params>
-class btree : public Params::key_compare {
- typedef btree<Params> self_type;
- typedef btree_node<Params> 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 class btree_internal_locate_plain_compare;
- friend class btree_internal_locate_compare_to;
- typedef typename if_<
- is_key_compare_to::value,
- btree_internal_locate_compare_to,
- btree_internal_locate_plain_compare>::type 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<internal_allocator_type, node_type*>). 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 <typename Base, typename Data>
- 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<node_type, reference, pointer> iterator;
- typedef typename iterator::const_iterator const_iterator;
- typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
- typedef std::reverse_iterator<iterator> reverse_iterator;
-
- typedef typename Params::allocator_type allocator_type;
- typedef typename allocator_type::template rebind<char>::other
- internal_allocator_type;
-
- 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);
- }
- iterator end() {
- return iterator(rightmost(), rightmost() ? rightmost()->count() : 0);
- }
- const_iterator end() 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());
- }
- reverse_iterator rend() {
- return reverse_iterator(begin());
- }
- const_reverse_iterator rend() 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<iterator,iterator> equal_range(const key_type &key) {
- return std::make_pair(lower_bound(key), upper_bound(key));
- }
- std::pair<const_iterator,const_iterator> 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. The
- // ValuePointer type is used to avoid instatiating the value unless the key
- // is being inserted. Value is not dereferenced if the key already exists in
- // the btree. See btree_map::operator[].
- template <typename ValuePointer>
- std::pair<iterator,bool> insert_unique(const key_type &key, ValuePointer value);
-
- // Inserts a value into the btree only if it does not already exist. The
- // boolean return value indicates whether insertion succeeded or failed.
- std::pair<iterator,bool> insert_unique(const value_type &v) {
- return insert_unique(params_type::key(v), &v);
- }
-
- // 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 insert_unique(v) were made.
- iterator insert_unique(iterator position, const value_type &v);
-
- // Insert a range of values into the btree.
- template <typename InputIterator>
- void insert_unique(InputIterator b, InputIterator e);
-
- // Inserts a value into the btree. The ValuePointer type is used to avoid
- // instatiating the value unless the key is being inserted. Value is not
- // dereferenced if the key already exists in the btree. See
- // btree_map::operator[].
- template <typename ValuePointer>
- iterator insert_multi(const key_type &key, ValuePointer value);
-
- // Inserts a value into the btree.
- iterator insert_multi(const value_type &v) {
- return insert_multi(params_type::key(v), &v);
- }
-
- // 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 insert_multi(v) were made.
- iterator insert_multi(iterator position, const value_type &v);
-
- // Insert a range of values into the btree.
- template <typename InputIterator>
- void insert_multi(InputIterator b, InputIterator e);
-
- 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(iterator iter);
-
- // Erases range. Returns the number of keys erased.
- int erase(iterator begin, 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* mutable_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() != NULL) {
- 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()->leaf()) return root()->count();
- return root()->size();
- }
- size_type max_size() const { return std::numeric_limits<size_type>::max(); }
- bool empty() const { return root() == NULL; }
-
- // 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->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** mutable_root() { return &root_.data; }
-
- // The rightmost node is stored in the root node.
- node_type* rightmost() {
- return (!root() || root()->leaf()) ? root() : root()->rightmost();
- }
- const node_type* rightmost() const {
- return (!root() || root()->leaf()) ? root() : root()->rightmost();
- }
- node_type** mutable_rightmost() { return root()->mutable_rightmost(); }
-
- // The leftmost node is stored as the parent of the root node.
- node_type* leftmost() { return root() ? root()->parent() : NULL; }
- const node_type* leftmost() const { return root() ? root()->parent() : NULL; }
-
- // The size of the tree is stored in the root node.
- size_type* mutable_size() { return root()->mutable_size(); }
-
- // Allocator routines.
- internal_allocator_type* mutable_internal_allocator() {
- return static_cast<internal_allocator_type*>(&root_);
- }
- const internal_allocator_type& internal_allocator() const {
- return *static_cast<const internal_allocator_type*>(&root_);
- }
-
- // Node creation/deletion routines.
- node_type* new_internal_node(node_type *parent) {
- internal_fields *p = reinterpret_cast<internal_fields*>(
- mutable_internal_allocator()->allocate(sizeof(internal_fields)));
- return node_type::init_internal(p, parent);
- }
- node_type* new_internal_root_node() {
- root_fields *p = reinterpret_cast<root_fields*>(
- mutable_internal_allocator()->allocate(sizeof(root_fields)));
- return node_type::init_root(p, root()->parent());
- }
- node_type* new_leaf_node(node_type *parent) {
- leaf_fields *p = reinterpret_cast<leaf_fields*>(
- mutable_internal_allocator()->allocate(sizeof(leaf_fields)));
- return node_type::init_leaf(p, parent, kNodeValues);
- }
- node_type* new_leaf_root_node(int max_count) {
- leaf_fields *p = reinterpret_cast<leaf_fields*>(
- mutable_internal_allocator()->allocate(
- sizeof(base_fields) + max_count * sizeof(value_type)));
- return node_type::init_leaf(p, reinterpret_cast<node_type*>(p), max_count);
- }
- void delete_internal_node(node_type *node) {
- node->destroy();
- assert(node != root());
- mutable_internal_allocator()->deallocate(
- reinterpret_cast<char*>(node), sizeof(internal_fields));
- }
- void delete_internal_root_node() {
- root()->destroy();
- mutable_internal_allocator()->deallocate(
- reinterpret_cast<char*>(root()), sizeof(root_fields));
- }
- void delete_leaf_node(node_type *node) {
- node->destroy();
- mutable_internal_allocator()->deallocate(
- reinterpret_cast<char*>(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(iterator *iter);
-
- // Tries to shrink the height of the tree by 1.
- void try_shrink();
-
- iterator internal_end(iterator iter) {
- return iter.node ? iter : 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).
- iterator internal_insert(iterator iter, const value_type &v);
-
- // 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 <typename IterType>
- 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 <typename IterType>
- std::pair<IterType, int> internal_locate(
- const key_type &key, IterType iter) const;
- template <typename IterType>
- std::pair<IterType, int> internal_locate_plain_compare(
- const key_type &key, IterType iter) const;
- template <typename IterType>
- std::pair<IterType, int> internal_locate_compare_to(
- const key_type &key, IterType iter) const;
-
- // Internal routine which implements lower_bound().
- template <typename IterType>
- IterType internal_lower_bound(
- const key_type &key, IterType iter) const;
-
- // Internal routine which implements upper_bound().
- template <typename IterType>
- IterType internal_upper_bound(
- const key_type &key, IterType iter) const;
-
- // Internal routine which implements find_unique().
- template <typename IterType>
- IterType internal_find_unique(
- const key_type &key, IterType iter) const;
-
- // Internal routine which implements find_multi().
- template <typename IterType>
- 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->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<internal_allocator_type, node_type*> 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 <typename R>
- static typename if_<
- if_<is_key_compare_to::value,
- std::is_same<R, int>,
- std::is_same<R, bool> >::type::value,
- big_, small_>::type 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 <typename P>
-inline void btree_node<P>::insert_value(int i, const value_type &x) {
- assert(i <= count());
- value_init(count(), x);
- for (int j = count(); j > i; --j) {
- value_swap(j, this, j - 1);
- }
- set_count(count() + 1);
-
- if (!leaf()) {
- ++i;
- for (int j = count(); j > i; --j) {
- *mutable_child(j) = child(j - 1);
- child(j)->set_position(j);
- }
- *mutable_child(i) = NULL;
- }
-}
-
-template <typename P>
-inline void btree_node<P>::remove_value(int i) {
- if (!leaf()) {
- assert(child(i + 1)->count() == 0);
- for (int j = i + 1; j < count(); ++j) {
- *mutable_child(j) = child(j + 1);
- child(j)->set_position(j);
- }
- *mutable_child(count()) = NULL;
- }
-
- set_count(count() - 1);
- for (; i < count(); ++i) {
- value_swap(i, this, i + 1);
- }
- value_destroy(i);
-}
-
-template <typename P>
-void btree_node<P>::rebalance_right_to_left(btree_node *src, int to_move) {
- assert(parent() == src->parent());
- assert(position() + 1 == src->position());
- assert(src->count() >= count());
- assert(to_move >= 1);
- assert(to_move <= src->count());
-
- // Make room in the left node for the new values.
- for (int i = 0; i < to_move; ++i) {
- value_init(i + count());
- }
-
- // Move the delimiting value to the left node and the new delimiting value
- // from the right node.
- value_swap(count(), parent(), position());
- parent()->value_swap(position(), src, to_move - 1);
-
- // Move the values from the right to the left node.
- for (int i = 1; i < to_move; ++i) {
- value_swap(count() + i, src, i - 1);
- }
- // Shift the values in the right node to their correct position.
- for (int i = to_move; i < src->count(); ++i) {
- src->value_swap(i - to_move, src, i);
- }
- for (int i = 1; i <= to_move; ++i) {
- src->value_destroy(src->count() - i);
- }
-
- if (!leaf()) {
- // Move the child pointers from the right to the left node.
- for (int i = 0; i < to_move; ++i) {
- set_child(1 + count() + i, src->child(i));
- }
- for (int i = 0; i <= src->count() - to_move; ++i) {
- assert(i + to_move <= src->max_count());
- src->set_child(i, src->child(i + to_move));
- *src->mutable_child(i + to_move) = NULL;
- }
- }
-
- // Fixup the counts on the src and dest nodes.
- set_count(count() + to_move);
- src->set_count(src->count() - to_move);
-}
-
-template <typename P>
-void btree_node<P>::rebalance_left_to_right(btree_node *dest, int to_move) {
- assert(parent() == dest->parent());
- assert(position() + 1 == dest->position());
- assert(count() >= dest->count());
- assert(to_move >= 1);
- assert(to_move <= count());
-
- // Make room in the right node for the new values.
- for (int i = 0; i < to_move; ++i) {
- dest->value_init(i + dest->count());
- }
- for (int i = dest->count() - 1; i >= 0; --i) {
- dest->value_swap(i, dest, i + to_move);
- }
-
- // Move the delimiting value to the right node and the new delimiting value
- // from the left node.
- dest->value_swap(to_move - 1, parent(), position());
- parent()->value_swap(position(), this, count() - to_move);
- value_destroy(count() - to_move);
-
- // Move the values from the left to the right node.
- for (int i = 1; i < to_move; ++i) {
- value_swap(count() - to_move + i, dest, i - 1);
- value_destroy(count() - to_move + i);
- }
-
- if (!leaf()) {
- // Move the child pointers from the left to the right node.
- for (int i = dest->count(); i >= 0; --i) {
- dest->set_child(i + to_move, dest->child(i));
- *dest->mutable_child(i) = NULL;
- }
- for (int i = 1; i <= to_move; ++i) {
- dest->set_child(i - 1, child(count() - to_move + i));
- *mutable_child(count() - to_move + i) = NULL;
- }
- }
-
- // Fixup the counts on the src and dest nodes.
- set_count(count() - to_move);
- dest->set_count(dest->count() + to_move);
-}
-
-template <typename P>
-void btree_node<P>::split(btree_node *dest, int insert_position) {
- assert(dest->count() == 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) {
- dest->set_count(count() - 1);
- } else if (insert_position == max_count()) {
- dest->set_count(0);
- } else {
- dest->set_count(count() / 2);
- }
- set_count(count() - dest->count());
- assert(count() >= 1);
-
- // Move values from the left sibling to the right sibling.
- for (int i = 0; i < dest->count(); ++i) {
- dest->value_init(i);
- value_swap(count() + i, dest, i);
- value_destroy(count() + i);
- }
-
- // The split key is the largest value in the left sibling.
- set_count(count() - 1);
- parent()->insert_value(position(), value_type());
- value_swap(count(), parent(), position());
- value_destroy(count());
- parent()->set_child(position() + 1, dest);
-
- if (!leaf()) {
- for (int i = 0; i <= dest->count(); ++i) {
- assert(child(count() + i + 1) != NULL);
- dest->set_child(i, child(count() + i + 1));
- *mutable_child(count() + i + 1) = NULL;
- }
- }
-}
-
-template <typename P>
-void btree_node<P>::merge(btree_node *src) {
- assert(parent() == src->parent());
- assert(position() + 1 == src->position());
-
- // Move the delimiting value to the left node.
- value_init(count());
- value_swap(count(), parent(), position());
-
- // Move the values from the right to the left node.
- for (int i = 0; i < src->count(); ++i) {
- value_init(1 + count() + i);
- value_swap(1 + count() + i, src, i);
- src->value_destroy(i);
- }
-
- if (!leaf()) {
- // Move the child pointers from the right to the left node.
- for (int i = 0; i <= src->count(); ++i) {
- set_child(1 + count() + i, src->child(i));
- *src->mutable_child(i) = NULL;
- }
- }
-
- // Fixup the counts on the src and dest nodes.
- set_count(1 + count() + src->count());
- src->set_count(0);
-
- // Remove the value on the parent node.
- parent()->remove_value(position());
-}
-
-template <typename P>
-void btree_node<P>::swap(btree_node *x) {
- assert(leaf() == x->leaf());
-
- // Swap the values.
- for (int i = count(); i < x->count(); ++i) {
- value_init(i);
- }
- for (int i = x->count(); i < count(); ++i) {
- x->value_init(i);
- }
- int n = std::max(count(), x->count());
- for (int i = 0; i < n; ++i) {
- value_swap(i, x, i);
- }
- for (int i = count(); i < x->count(); ++i) {
- x->value_destroy(i);
- }
- for (int i = x->count(); i < count(); ++i) {
- value_destroy(i);
- }
-
- if (!leaf()) {
- // Swap the child pointers.
- for (int i = 0; i <= n; ++i) {
- btree_swap_helper(*mutable_child(i), *x->mutable_child(i));
- }
- for (int i = 0; i <= count(); ++i) {
- x->child(i)->fields_.parent = x;
- }
- for (int i = 0; i <= x->count(); ++i) {
- child(i)->fields_.parent = this;
- }
- }
-
- // Swap the counts.
- btree_swap_helper(fields_.count, x->fields_.count);
-}
-
-////
-// btree_iterator methods
-template <typename N, typename R, typename P>
-void btree_iterator<N, R, P>::increment_slow() {
- if (node->leaf()) {
- assert(position >= node->count());
- self_type save(*this);
- while (position == node->count() && !node->is_root()) {
- assert(node->parent()->child(node->position()) == node);
- position = node->position();
- node = node->parent();
- }
- if (position == node->count()) {
- *this = save;
- }
- } else {
- assert(position < node->count());
- node = node->child(position + 1);
- while (!node->leaf()) {
- node = node->child(0);
- }
- position = 0;
- }
-}
-
-template <typename N, typename R, typename P>
-void btree_iterator<N, R, P>::increment_by(int count) {
- while (count > 0) {
- if (node->leaf()) {
- int rest = node->count() - position;
- position += std::min(rest, count);
- count = count - rest;
- if (position < node->count()) {
- return;
- }
- } else {
- --count;
- }
- increment_slow();
- }
-}
-
-template <typename N, typename R, typename P>
-void btree_iterator<N, R, P>::decrement_slow() {
- if (node->leaf()) {
- assert(position <= -1);
- self_type save(*this);
- while (position < 0 && !node->is_root()) {
- assert(node->parent()->child(node->position()) == node);
- position = node->position() - 1;
- node = node->parent();
- }
- if (position < 0) {
- *this = save;
- }
- } else {
- assert(position >= 0);
- node = node->child(position);
- while (!node->leaf()) {
- node = node->child(node->count());
- }
- position = node->count() - 1;
- }
-}
-
-////
-// btree methods
-template <typename P>
-btree<P>::btree(const key_compare &comp, const allocator_type &alloc)
- : key_compare(comp),
- root_(alloc, NULL) {
-}
-
-template <typename P>
-btree<P>::btree(const self_type &x)
- : key_compare(x.key_comp()),
- root_(x.internal_allocator(), NULL) {
- assign(x);
-}
-
-template <typename P> template <typename ValuePointer>
-std::pair<typename btree<P>::iterator, bool>
-btree<P>::insert_unique(const key_type &key, ValuePointer value) {
- if (empty()) {
- *mutable_root() = new_leaf_root_node(1);
- }
-
- std::pair<iterator, int> 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_insert(iter, *value), true);
-}
-
-template <typename P>
-inline typename btree<P>::iterator
-btree<P>::insert_unique(iterator position, const value_type &v) {
- if (!empty()) {
- const key_type &key = params_type::key(v);
- if (position == end() || compare_keys(key, position.key())) {
- iterator prev = position;
- if (position == begin() || compare_keys((--prev).key(), key)) {
- // prev.key() < key < position.key()
- return internal_insert(position, v);
- }
- } else if (compare_keys(position.key(), key)) {
- iterator next = position;
- ++next;
- if (next == end() || compare_keys(key, next.key())) {
- // position.key() < key < next.key()
- return internal_insert(next, v);
- }
- } else {
- // position.key() == key
- return position;
- }
- }
- return insert_unique(v).first;
-}
-
-template <typename P> template <typename InputIterator>
-void btree<P>::insert_unique(InputIterator b, InputIterator e) {
- for (; b != e; ++b) {
- insert_unique(end(), *b);
- }
-}
-
-template <typename P> template <typename ValuePointer>
-typename btree<P>::iterator
-btree<P>::insert_multi(const key_type &key, ValuePointer value) {
- if (empty()) {
- *mutable_root() = new_leaf_root_node(1);
- }
-
- iterator iter = internal_upper_bound(key, iterator(root(), 0));
- if (!iter.node) {
- iter = end();
- }
- return internal_insert(iter, *value);
-}
-
-template <typename P>
-typename btree<P>::iterator
-btree<P>::insert_multi(iterator position, const value_type &v) {
- if (!empty()) {
- const key_type &key = params_type::key(v);
- if (position == end() || !compare_keys(position.key(), key)) {
- iterator prev = position;
- if (position == begin() || !compare_keys(key, (--prev).key())) {
- // prev.key() <= key <= position.key()
- return internal_insert(position, v);
- }
- } else {
- iterator next = position;
- ++next;
- if (next == end() || !compare_keys(next.key(), key)) {
- // position.key() < key <= next.key()
- return internal_insert(next, v);
- }
- }
- }
- return insert_multi(v);
-}
-
-template <typename P> template <typename InputIterator>
-void btree<P>::insert_multi(InputIterator b, InputIterator e) {
- for (; b != e; ++b) {
- insert_multi(end(), *b);
- }
-}
-
-template <typename P>
-void btree<P>::assign(const self_type &x) {
- clear();
-
- *mutable_key_comp() = x.key_comp();
- *mutable_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()) {
- insert_multi(*iter);
- } else {
- // If the btree is not empty, we can just insert the new value at the end
- // of the tree!
- internal_insert(end(), *iter);
- }
- }
-}
-
-template <typename P>
-typename btree<P>::iterator btree<P>::erase(iterator iter) {
- bool internal_delete = false;
- if (!iter.node->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.
- iterator tmp_iter(iter--);
- assert(iter.node->leaf());
- assert(!compare_keys(tmp_iter.key(), iter.key()));
- iter.node->value_swap(iter.position, tmp_iter.node, tmp_iter.position);
- internal_delete = true;
- --*mutable_size();
- } else if (!root()->leaf()) {
- --*mutable_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);
- 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->leaf()) {
- res = iter;
- }
- if (!merged) {
- break;
- }
- iter.node = iter.node->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 <typename P>
-int btree<P>::erase(iterator begin, iterator end) {
- int count = distance(begin, end);
- for (int i = 0; i < count; i++) {
- begin = erase(begin);
- }
- return count;
-}
-
-template <typename P>
-int btree<P>::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 <typename P>
-int btree<P>::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 <typename P>
-void btree<P>::clear() {
- if (root() != NULL) {
- internal_clear(root());
- }
- *mutable_root() = NULL;
-}
-
-template <typename P>
-void btree<P>::swap(self_type &x) {
- std::swap(static_cast<key_compare&>(*this), static_cast<key_compare&>(x));
- std::swap(root_, x.root_);
-}
-
-template <typename P>
-void btree<P>::verify() const {
- if (root() != NULL) {
- assert(size() == internal_verify(root(), NULL, NULL));
- assert(leftmost() == (++const_iterator(root(), -1)).node);
- assert(rightmost() == (--const_iterator(root(), root()->count())).node);
- assert(leftmost()->leaf());
- assert(rightmost()->leaf());
- } else {
- assert(size() == 0);
- assert(leftmost() == NULL);
- assert(rightmost() == NULL);
- }
-}
-
-template <typename P>
-void btree<P>::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->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->parent(), node->position());
- rebalance_or_split(&parent_iter);
- }
- } else {
- // Rebalancing not possible because this is the root node.
- if (root()->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());
- *mutable_root() = parent;
- assert(*mutable_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->leaf()) {
- split_node = new_leaf_node(parent);
- node->split(split_node, insert_position);
- if (rightmost() == node) {
- *mutable_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 <typename P>
-void btree<P>::merge_nodes(node_type *left, node_type *right) {
- left->merge(right);
- if (right->leaf()) {
- if (rightmost() == right) {
- *mutable_rightmost() = left;
- }
- delete_leaf_node(right);
- } else {
- delete_internal_node(right);
- }
-}
-
-template <typename P>
-bool btree<P>::try_merge_or_rebalance(iterator *iter) {
- node_type *parent = iter->node->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 <typename P>
-void btree<P>::try_shrink() {
- if (root()->count() > 0) {
- return;
- }
- // Deleted the last item on the root node, shrink the height of the tree.
- if (root()->leaf()) {
- assert(size() == 0);
- delete_leaf_node(root());
- *mutable_root() = NULL;
- } else {
- node_type *child = root()->child(0);
- if (child->leaf()) {
- // The child is a leaf node so simply make it the root node in the tree.
- child->make_root();
- delete_internal_root_node();
- *mutable_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 <typename P> template <typename IterType>
-inline IterType btree<P>::internal_last(IterType iter) {
- while (iter.node && iter.position == iter.node->count()) {
- iter.position = iter.node->position();
- iter.node = iter.node->parent();
- if (iter.node->leaf()) {
- iter.node = NULL;
- }
- }
- return iter;
-}
-
-template <typename P>
-inline typename btree<P>::iterator
-btree<P>::internal_insert(iterator iter, const value_type &v) {
- if (!iter.node->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<int>(kNodeValues, 2 * iter.node->max_count()));
- iter.node->swap(root());
- delete_leaf_node(root());
- *mutable_root() = iter.node;
- } else {
- rebalance_or_split(&iter);
- ++*mutable_size();
- }
- } else if (!root()->leaf()) {
- ++*mutable_size();
- }
- iter.node->insert_value(iter.position, v);
- return iter;
-}
-
-template <typename P> template <typename IterType>
-inline std::pair<IterType, int> btree<P>::internal_locate(
- const key_type &key, IterType iter) const {
- return internal_locate_type::dispatch(key, *this, iter);
-}
-
-template <typename P> template <typename IterType>
-inline std::pair<IterType, int> btree<P>::internal_locate_plain_compare(
- const key_type &key, IterType iter) const {
- for (;;) {
- iter.position = iter.node->lower_bound(key, key_comp());
- if (iter.node->leaf()) {
- break;
- }
- iter.node = iter.node->child(iter.position);
- }
- return std::make_pair(iter, 0);
-}
-
-template <typename P> template <typename IterType>
-inline std::pair<IterType, int> btree<P>::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<int>(kExactMatch));
- }
- if (iter.node->leaf()) {
- break;
- }
- iter.node = iter.node->child(iter.position);
- }
- return std::make_pair(iter, -kExactMatch);
-}
-
-template <typename P> template <typename IterType>
-IterType btree<P>::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->leaf()) {
- break;
- }
- iter.node = iter.node->child(iter.position);
- }
- iter = internal_last(iter);
- }
- return iter;
-}
-
-template <typename P> template <typename IterType>
-IterType btree<P>::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->leaf()) {
- break;
- }
- iter.node = iter.node->child(iter.position);
- }
- iter = internal_last(iter);
- }
- return iter;
-}
-
-template <typename P> template <typename IterType>
-IterType btree<P>::internal_find_unique(
- const key_type &key, IterType iter) const {
- if (iter.node) {
- std::pair<IterType, int> 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(NULL, 0);
-}
-
-template <typename P> template <typename IterType>
-IterType btree<P>::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(NULL, 0);
-}
-
-template <typename P>
-void btree<P>::internal_clear(node_type *node) {
- if (!node->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 <typename P>
-void btree<P>::internal_dump(
- std::ostream &os, const node_type *node, int level) const {
- for (int i = 0; i < node->count(); ++i) {
- if (!node->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->leaf()) {
- internal_dump(os, node->child(node->count()), level + 1);
- }
-}
-
-template <typename P>
-int btree<P>::internal_verify(
- const node_type *node, const key_type *lo, const key_type *hi) const {
- assert(node->count() > 0);
- 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->leaf()) {
- for (int i = 0; i <= node->count(); ++i) {
- assert(node->child(i) != NULL);
- assert(node->child(i)->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));
- }
- }
- return count;
-}
-
-} // namespace btree
-
-#endif // UTIL_BTREE_BTREE_H__
Code Review / stor4nfv.git / blobdiff