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2845 lines
79 KiB
C++
2845 lines
79 KiB
C++
// Copyright 2013 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// A btree implementation of the STL set and map interfaces. A btree is both
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// smaller and faster than STL set/map. The red-black tree implementation of
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// STL set/map has an overhead of 3 pointers (left, right and parent) plus the
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// node color information for each stored value. So a set<int32> consumes 20
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// bytes for each value stored. This btree implementation stores multiple
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// values on fixed size nodes (usually 256 bytes) and doesn't store child
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// pointers for leaf nodes. The result is that a btree_set<int32> may use much
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// less memory per stored value. For the random insertion benchmark in
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// btree_test.cc, a btree_set<int32> with node-size of 256 uses 4.9 bytes per
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// stored value.
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//
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// The packing of multiple values on to each node of a btree has another effect
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// besides better space utilization: better cache locality due to fewer cache
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// lines being accessed. Better cache locality translates into faster
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// operations.
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//
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// CAVEATS
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//
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// Insertions and deletions on a btree can cause splitting, merging or
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// rebalancing of btree nodes. And even without these operations, insertions
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// and deletions on a btree will move values around within a node. In both
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// cases, the result is that insertions and deletions can invalidate iterators
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// pointing to values other than the one being inserted/deleted. This is
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// notably different from STL set/map which takes care to not invalidate
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// iterators on insert/erase except, of course, for iterators pointing to the
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// value being erased. A partial workaround when erasing is available:
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// erase() returns an iterator pointing to the item just after the one that was
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// erased (or end() if none exists). See also safe_btree.
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// PERFORMANCE
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//
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// btree_bench --benchmarks=. 2>&1 | ./benchmarks.awk
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//
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// Run on pmattis-warp.nyc (4 X 2200 MHz CPUs); 2010/03/04-15:23:06
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// Benchmark STL(ns) B-Tree(ns) @ <size>
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// --------------------------------------------------------
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// BM_set_int32_insert 1516 608 +59.89% <256> [40.0, 5.2]
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// BM_set_int32_lookup 1160 414 +64.31% <256> [40.0, 5.2]
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// BM_set_int32_fulllookup 960 410 +57.29% <256> [40.0, 4.4]
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// BM_set_int32_delete 1741 528 +69.67% <256> [40.0, 5.2]
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// BM_set_int32_queueaddrem 3078 1046 +66.02% <256> [40.0, 5.5]
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// BM_set_int32_mixedaddrem 3600 1384 +61.56% <256> [40.0, 5.3]
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// BM_set_int32_fifo 227 113 +50.22% <256> [40.0, 4.4]
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// BM_set_int32_fwditer 158 26 +83.54% <256> [40.0, 5.2]
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// BM_map_int32_insert 1551 636 +58.99% <256> [48.0, 10.5]
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// BM_map_int32_lookup 1200 508 +57.67% <256> [48.0, 10.5]
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// BM_map_int32_fulllookup 989 487 +50.76% <256> [48.0, 8.8]
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// BM_map_int32_delete 1794 628 +64.99% <256> [48.0, 10.5]
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// BM_map_int32_queueaddrem 3189 1266 +60.30% <256> [48.0, 11.6]
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// BM_map_int32_mixedaddrem 3822 1623 +57.54% <256> [48.0, 10.9]
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// BM_map_int32_fifo 151 134 +11.26% <256> [48.0, 8.8]
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// BM_map_int32_fwditer 161 32 +80.12% <256> [48.0, 10.5]
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// BM_set_int64_insert 1546 636 +58.86% <256> [40.0, 10.5]
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// BM_set_int64_lookup 1200 512 +57.33% <256> [40.0, 10.5]
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// BM_set_int64_fulllookup 971 487 +49.85% <256> [40.0, 8.8]
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// BM_set_int64_delete 1745 616 +64.70% <256> [40.0, 10.5]
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// BM_set_int64_queueaddrem 3163 1195 +62.22% <256> [40.0, 11.6]
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// BM_set_int64_mixedaddrem 3760 1564 +58.40% <256> [40.0, 10.9]
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// BM_set_int64_fifo 146 103 +29.45% <256> [40.0, 8.8]
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// BM_set_int64_fwditer 162 31 +80.86% <256> [40.0, 10.5]
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// BM_map_int64_insert 1551 720 +53.58% <256> [48.0, 20.7]
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// BM_map_int64_lookup 1214 612 +49.59% <256> [48.0, 20.7]
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// BM_map_int64_fulllookup 994 592 +40.44% <256> [48.0, 17.2]
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// BM_map_int64_delete 1778 764 +57.03% <256> [48.0, 20.7]
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// BM_map_int64_queueaddrem 3189 1547 +51.49% <256> [48.0, 20.9]
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// BM_map_int64_mixedaddrem 3779 1887 +50.07% <256> [48.0, 21.6]
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// BM_map_int64_fifo 147 145 +1.36% <256> [48.0, 17.2]
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// BM_map_int64_fwditer 162 41 +74.69% <256> [48.0, 20.7]
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// BM_set_string_insert 1989 1966 +1.16% <256> [64.0, 44.5]
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// BM_set_string_lookup 1709 1600 +6.38% <256> [64.0, 44.5]
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// BM_set_string_fulllookup 1573 1529 +2.80% <256> [64.0, 35.4]
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// BM_set_string_delete 2520 1920 +23.81% <256> [64.0, 44.5]
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// BM_set_string_queueaddrem 4706 4309 +8.44% <256> [64.0, 48.3]
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// BM_set_string_mixedaddrem 5080 4654 +8.39% <256> [64.0, 46.7]
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// BM_set_string_fifo 318 512 -61.01% <256> [64.0, 35.4]
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// BM_set_string_fwditer 182 93 +48.90% <256> [64.0, 44.5]
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// BM_map_string_insert 2600 2227 +14.35% <256> [72.0, 55.8]
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// BM_map_string_lookup 2068 1730 +16.34% <256> [72.0, 55.8]
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// BM_map_string_fulllookup 1859 1618 +12.96% <256> [72.0, 44.0]
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// BM_map_string_delete 3168 2080 +34.34% <256> [72.0, 55.8]
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// BM_map_string_queueaddrem 5840 4701 +19.50% <256> [72.0, 59.4]
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// BM_map_string_mixedaddrem 6400 5200 +18.75% <256> [72.0, 57.8]
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// BM_map_string_fifo 398 596 -49.75% <256> [72.0, 44.0]
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// BM_map_string_fwditer 243 113 +53.50% <256> [72.0, 55.8]
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#pragma once
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#include <assert.h>
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#include <stddef.h>
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#include <string.h>
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#include <sys/types.h>
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#include <algorithm>
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#include <functional>
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#include <iostream>
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#include <iterator>
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#include <limits>
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#include "type_traits_hm"
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#include <new>
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#include <ostream>
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#include <string>
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#include <utility>
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#ifndef NDEBUG
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#define NDEBUG 1
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#endif
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namespace btree
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{
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// Inside a btree method, if we just call swap(), it will choose the
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// btree::swap method, which we don't want. And we can't say ::swap
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// because then MSVC won't pickup any std::swap() implementations. We
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// can't just use std::swap() directly because then we don't get the
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// specialization for types outside the std namespace. So the solution
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// is to have a special swap helper function whose name doesn't
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// collide with other swap functions defined by the btree classes.
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template <typename T>
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inline void btree_swap_helper(T& a, T& b)
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{
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using std::swap;
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swap(a, b);
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}
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// A template helper used to select A or B based on a condition.
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template <bool cond, typename A, typename B>
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struct if_
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{
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typedef A type;
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};
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template <typename A, typename B>
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struct if_<false, A, B>
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{
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typedef B type;
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};
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// Types small_ and big_ are promise that sizeof(small_) < sizeof(big_)
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typedef char small_;
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struct big_
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{
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char dummy[2];
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};
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// A compile-time assertion.
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template <bool>
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struct CompileAssert
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{
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};
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#define COMPILE_ASSERT(expr, msg) typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
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// A helper type used to indicate that a key-compare-to functor has been
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// provided. A user can specify a key-compare-to functor by doing:
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//
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// struct MyStringComparer
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// : public util::btree::btree_key_compare_to_tag {
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// int operator()(const string &a, const string &b) const {
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// return a.compare(b);
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// }
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// };
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//
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// Note that the return type is an int and not a bool. There is a
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// COMPILE_ASSERT which enforces this return type.
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struct btree_key_compare_to_tag
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{
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};
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// A helper class that indicates if the Compare parameter is derived from
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// btree_key_compare_to_tag.
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template <typename Compare>
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struct btree_is_key_compare_to : public std::is_convertible<Compare, btree_key_compare_to_tag>
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{
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};
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// A helper class to convert a boolean comparison into a three-way
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// "compare-to" comparison that returns a negative value to indicate
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// less-than, zero to indicate equality and a positive value to
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// indicate greater-than. This helper class is specialized for
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// less<string> and greater<string>. The btree_key_compare_to_adapter
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// class is provided so that btree users automatically get the more
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// efficient compare-to code when using common google string types
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// with common comparison functors.
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template <typename Compare>
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struct btree_key_compare_to_adapter : Compare
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{
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btree_key_compare_to_adapter()
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{
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}
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btree_key_compare_to_adapter(const Compare& c) : Compare(c)
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{
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}
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btree_key_compare_to_adapter(const btree_key_compare_to_adapter<Compare>& c) : Compare(c)
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{
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}
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};
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template <>
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struct btree_key_compare_to_adapter<std::less<std::string> > : public btree_key_compare_to_tag
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{
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btree_key_compare_to_adapter()
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{
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}
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btree_key_compare_to_adapter(const std::less<std::string>&)
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{
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}
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btree_key_compare_to_adapter(const btree_key_compare_to_adapter<std::less<std::string> >&)
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{
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}
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int operator()(const std::string& a, const std::string& b) const
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{
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return a.compare(b);
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}
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};
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template <>
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struct btree_key_compare_to_adapter<std::greater<std::string> > : public btree_key_compare_to_tag
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{
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btree_key_compare_to_adapter()
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{
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}
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btree_key_compare_to_adapter(const std::greater<std::string>&)
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{
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}
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btree_key_compare_to_adapter(const btree_key_compare_to_adapter<std::greater<std::string> >&)
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{
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}
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int operator()(const std::string& a, const std::string& b) const
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{
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return b.compare(a);
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}
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};
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// A helper class that allows a compare-to functor to behave like a plain
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// compare functor. This specialization is used when we do not have a
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// compare-to functor.
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template <typename Key, typename Compare, bool HaveCompareTo>
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struct btree_key_comparer
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{
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btree_key_comparer()
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{
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}
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btree_key_comparer(Compare c) : comp(c)
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{
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}
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static bool bool_compare(const Compare& comp, const Key& x, const Key& y)
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{
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return comp(x, y);
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}
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bool operator()(const Key& x, const Key& y) const
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{
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return bool_compare(comp, x, y);
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}
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Compare comp;
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};
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// A specialization of btree_key_comparer when a compare-to functor is
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// present. We need a plain (boolean) comparison in some parts of the btree
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// code, such as insert-with-hint.
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template <typename Key, typename Compare>
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struct btree_key_comparer<Key, Compare, true>
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{
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btree_key_comparer()
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{
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}
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btree_key_comparer(Compare c) : comp(c)
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{
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}
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static bool bool_compare(const Compare& comp, const Key& x, const Key& y)
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{
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return comp(x, y) < 0;
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}
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bool operator()(const Key& x, const Key& y) const
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{
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return bool_compare(comp, x, y);
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}
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Compare comp;
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};
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// A helper function to compare to keys using the specified compare
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// functor. This dispatches to the appropriate btree_key_comparer comparison,
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// depending on whether we have a compare-to functor or not (which depends on
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// whether Compare is derived from btree_key_compare_to_tag).
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template <typename Key, typename Compare>
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bool btree_compare_keys(const Compare& comp, const Key& x, const Key& y)
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{
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typedef btree_key_comparer<Key, Compare, btree_is_key_compare_to<Compare>::value> key_comparer;
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return key_comparer::bool_compare(comp, x, y);
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}
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template <typename Key, typename Compare, typename Alloc, int TargetNodeSize, int ValueSize>
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struct btree_common_params
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{
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// If Compare is derived from btree_key_compare_to_tag then use it as the
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// key_compare type. Otherwise, use btree_key_compare_to_adapter<> which will
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// fall-back to Compare if we don't have an appropriate specialization.
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typedef typename if_<btree_is_key_compare_to<Compare>::value, Compare,
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btree_key_compare_to_adapter<Compare> >::type key_compare;
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// A type which indicates if we have a key-compare-to functor or a plain old
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// key-compare functor.
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typedef btree_is_key_compare_to<key_compare> is_key_compare_to;
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typedef Alloc allocator_type;
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typedef Key key_type;
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typedef ssize_t size_type;
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typedef ptrdiff_t difference_type;
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enum
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{
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kTargetNodeSize = TargetNodeSize,
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// Available space for values. This is largest for leaf nodes,
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// which has overhead no fewer than two pointers.
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kNodeValueSpace = TargetNodeSize - 2 * sizeof(void*),
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};
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// This is an integral type large enough to hold as many
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// ValueSize-values as will fit a node of TargetNodeSize bytes.
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typedef typename if_<(kNodeValueSpace / ValueSize) >= 256, uint16_t, uint8_t>::type node_count_type;
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};
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// A parameters structure for holding the type parameters for a btree_map.
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template <typename Key, typename Data, typename Compare, typename Alloc, int TargetNodeSize>
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struct btree_map_params
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: public btree_common_params<Key, Compare, Alloc, TargetNodeSize, sizeof(Key) + sizeof(Data)>
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{
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typedef Data data_type;
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typedef Data mapped_type;
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typedef std::pair<const Key, data_type> value_type;
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typedef std::pair<Key, data_type> mutable_value_type;
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typedef value_type* pointer;
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typedef const value_type* const_pointer;
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typedef value_type& reference;
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typedef const value_type& const_reference;
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enum
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{
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kValueSize = sizeof(Key) + sizeof(data_type),
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};
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static const Key& key(const value_type& x)
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{
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return x.first;
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}
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static const Key& key(const mutable_value_type& x)
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{
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return x.first;
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}
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static void swap(mutable_value_type* a, mutable_value_type* b)
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{
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btree_swap_helper(a->first, b->first);
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btree_swap_helper(a->second, b->second);
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}
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};
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// A parameters structure for holding the type parameters for a btree_set.
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template <typename Key, typename Compare, typename Alloc, int TargetNodeSize>
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struct btree_set_params : public btree_common_params<Key, Compare, Alloc, TargetNodeSize, sizeof(Key)>
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{
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typedef std::false_type data_type;
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typedef std::false_type mapped_type;
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typedef Key value_type;
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typedef value_type mutable_value_type;
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typedef value_type* pointer;
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typedef const value_type* const_pointer;
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typedef value_type& reference;
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typedef const value_type& const_reference;
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enum
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{
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kValueSize = sizeof(Key),
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};
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static const Key& key(const value_type& x)
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{
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return x;
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}
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static void swap(mutable_value_type* a, mutable_value_type* b)
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{
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btree_swap_helper<mutable_value_type>(*a, *b);
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}
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};
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// An adapter class that converts a lower-bound compare into an upper-bound
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// compare.
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template <typename Key, typename Compare>
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struct btree_upper_bound_adapter : public Compare
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{
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btree_upper_bound_adapter(Compare c) : Compare(c)
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{
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}
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bool operator()(const Key& a, const Key& b) const
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{
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return !static_cast<const Compare&>(*this)(b, a);
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}
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};
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template <typename Key, typename CompareTo>
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struct btree_upper_bound_compare_to_adapter : public CompareTo
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{
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btree_upper_bound_compare_to_adapter(CompareTo c) : CompareTo(c)
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{
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}
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int operator()(const Key& a, const Key& b) const
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{
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return static_cast<const CompareTo&>(*this)(b, a);
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}
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};
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// Dispatch helper class for using linear search with plain compare.
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template <typename K, typename N, typename Compare>
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struct btree_linear_search_plain_compare
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{
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static int lower_bound(const K& k, const N& n, Compare comp)
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{
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return n.linear_search_plain_compare(k, 0, n.count(), comp);
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}
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static int upper_bound(const K& k, const N& n, Compare comp)
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{
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typedef btree_upper_bound_adapter<K, Compare> upper_compare;
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return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp));
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}
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|
};
|
|
|
|
// 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) : key_compare(comp), root_(alloc, NULL)
|
|
{
|
|
}
|
|
|
|
// Copy constructor.
|
|
btree(const self_type& x) : key_compare(x.key_comp()), root_(x.internal_allocator(), NULL)
|
|
{
|
|
assign(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)
|
|
{
|
|
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);
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
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;
|
|
}
|
|
|
|
// Insert a range of values into the btree.
|
|
template <typename InputIterator>
|
|
void insert_unique(InputIterator b, InputIterator e)
|
|
{
|
|
for (; b != e; ++b)
|
|
{
|
|
insert_unique(end(), *b);
|
|
}
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
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);
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
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);
|
|
}
|
|
|
|
// Insert a range of values into the btree.
|
|
template <typename InputIterator>
|
|
void insert_multi(InputIterator b, InputIterator e)
|
|
{
|
|
for (; b != e; ++b)
|
|
{
|
|
insert_multi(end(), *b);
|
|
}
|
|
}
|
|
|
|
void 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);
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
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;
|
|
}
|
|
|
|
// Erases range. Returns the number of keys erased.
|
|
int erase(iterator begin, iterator end)
|
|
{
|
|
int count = distance(begin, end);
|
|
|
|
for (int i = 0; i < count; i++)
|
|
{
|
|
begin = erase(begin);
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
// Erases the specified key from the btree. Returns 1 if an element was
|
|
// erased and 0 otherwise.
|
|
int 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;
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
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);
|
|
}
|
|
|
|
// 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()
|
|
{
|
|
if (root() != NULL)
|
|
{
|
|
internal_clear(root());
|
|
}
|
|
|
|
*mutable_root() = NULL;
|
|
}
|
|
|
|
// Swap the contents of *this and x.
|
|
void swap(self_type& x)
|
|
{
|
|
std::swap(static_cast<key_compare&>(*this), static_cast<key_compare&>(x));
|
|
std::swap(root_, x.root_);
|
|
}
|
|
|
|
// 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
|
|
{
|
|
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);
|
|
}
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
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;
|
|
}
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
left->merge(right);
|
|
|
|
if (right->leaf())
|
|
{
|
|
if (rightmost() == right)
|
|
{
|
|
*mutable_rightmost() = left;
|
|
}
|
|
|
|
delete_leaf_node(right);
|
|
}
|
|
else
|
|
{
|
|
delete_internal_node(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)
|
|
{
|
|
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;
|
|
}
|
|
|
|
// Tries to shrink the height of the tree by 1.
|
|
void 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);
|
|
}
|
|
}
|
|
}
|
|
|
|
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)
|
|
{
|
|
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;
|
|
}
|
|
|
|
// 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)
|
|
{
|
|
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;
|
|
}
|
|
|
|
// 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
|
|
{
|
|
return internal_locate_type::dispatch(key, *this, iter);
|
|
}
|
|
|
|
template <typename IterType>
|
|
std::pair<IterType, int> 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 IterType>
|
|
std::pair<IterType, int> 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);
|
|
}
|
|
|
|
// Internal routine which implements lower_bound().
|
|
template <typename IterType>
|
|
IterType 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;
|
|
}
|
|
|
|
// Internal routine which implements upper_bound().
|
|
template <typename IterType>
|
|
IterType 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;
|
|
}
|
|
|
|
// Internal routine which implements find_unique().
|
|
template <typename IterType>
|
|
IterType 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);
|
|
}
|
|
|
|
// Internal routine which implements find_multi().
|
|
template <typename IterType>
|
|
IterType 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);
|
|
}
|
|
|
|
// Deletes a node and all of its children.
|
|
void 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);
|
|
}
|
|
}
|
|
|
|
// 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
|
|
{
|
|
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);
|
|
}
|
|
}
|
|
|
|
// Verifies the tree structure of node.
|
|
int 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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
} // namespace btree
|