12bc53e031
-- c99f979ad34f155fbeeea69b88bdc7458d89a21c by Derek Mauro <dmauro@google.com>: Remove a floating point division by zero test. This isn't testing behavior related to the library, and MSVC warns about it in opt mode. PiperOrigin-RevId: 285220804 -- 68b015491f0dbf1ab547994673281abd1f34cd4b by Gennadiy Rozental <rogeeff@google.com>: This CL introduces following changes to the class FlagImpl: * We eliminate the CommandLineFlagLocks struct. Instead callback guard and callback function are combined into a single CallbackData struct, while primary data lock is stored separately. * CallbackData member of class FlagImpl is initially set to be nullptr and is only allocated and initialized when a flag's callback is being set. For most flags we do not pay for the extra space and extra absl::Mutex now. * Primary data guard is stored in data_guard_ data member. This is a properly aligned character buffer of necessary size. During initialization of the flag we construct absl::Mutex in this space using placement new call. * We now avoid extra value copy after successful attempt to parse value out of string. Instead we swap flag's current value with tentative value we just produced. PiperOrigin-RevId: 285132636 -- ed45d118fb818969eb13094cf7827c885dfc562c by Tom Manshreck <shreck@google.com>: Change null-term* (and nul-term*) to NUL-term* in comments PiperOrigin-RevId: 285036610 -- 729619017944db895ce8d6d29c1995aa2e5628a5 by Derek Mauro <dmauro@google.com>: Use the Posix implementation of thread identity on MinGW. Some versions of MinGW suffer from thread_local bugs. PiperOrigin-RevId: 285022920 -- 39a25493503c76885bc3254c28f66a251c5b5bb0 by Greg Falcon <gfalcon@google.com>: Implementation detail change. Add further ABSL_NAMESPACE_BEGIN and _END annotation macros to files in Abseil. PiperOrigin-RevId: 285012012 GitOrigin-RevId: c99f979ad34f155fbeeea69b88bdc7458d89a21c Change-Id: I4c85d3704e45d11a9ac50d562f39640a6adbedc1
2613 lines
91 KiB
C++
2613 lines
91 KiB
C++
// Copyright 2018 The Abseil Authors.
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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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// https://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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// A btree implementation of the STL set and map interfaces. A btree is smaller
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// and generally also faster than STL set/map (refer to the benchmarks below).
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// The red-black tree implementation of STL set/map has an overhead of 3
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// pointers (left, right and parent) plus the node color information for each
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// stored value. So a set<int32_t> consumes 40 bytes for each value stored in
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// 64-bit mode. This btree implementation stores multiple values on fixed
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// size nodes (usually 256 bytes) and doesn't store child pointers for leaf
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// nodes. The result is that a btree_set<int32_t> may use much less memory per
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// stored value. For the random insertion benchmark in btree_bench.cc, a
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// btree_set<int32_t> with node-size of 256 uses 5.1 bytes per 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. Therefore, this
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// container does not provide pointer stability. This is notably different from
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// STL set/map which takes care to not invalidate iterators on insert/erase
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// except, of course, for iterators pointing to the value being erased. A
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// partial workaround when erasing is available: erase() returns an iterator
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// pointing to the item just after the one that was erased (or end() if none
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// exists).
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#ifndef ABSL_CONTAINER_INTERNAL_BTREE_H_
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#define ABSL_CONTAINER_INTERNAL_BTREE_H_
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#include <algorithm>
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#include <cassert>
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#include <cstddef>
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#include <cstdint>
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#include <cstring>
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#include <functional>
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#include <iterator>
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#include <limits>
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#include <new>
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#include <string>
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#include <type_traits>
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#include <utility>
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#include "absl/base/macros.h"
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#include "absl/container/internal/common.h"
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#include "absl/container/internal/compressed_tuple.h"
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#include "absl/container/internal/container_memory.h"
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#include "absl/container/internal/layout.h"
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#include "absl/memory/memory.h"
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#include "absl/meta/type_traits.h"
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#include "absl/strings/string_view.h"
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#include "absl/types/compare.h"
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#include "absl/utility/utility.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace container_internal {
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// A helper class that indicates if the Compare parameter is a key-compare-to
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// comparator.
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template <typename Compare, typename T>
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using btree_is_key_compare_to =
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std::is_convertible<absl::result_of_t<Compare(const T &, const T &)>,
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absl::weak_ordering>;
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struct StringBtreeDefaultLess {
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using is_transparent = void;
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StringBtreeDefaultLess() = default;
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// Compatibility constructor.
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StringBtreeDefaultLess(std::less<std::string>) {} // NOLINT
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StringBtreeDefaultLess(std::less<string_view>) {} // NOLINT
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absl::weak_ordering operator()(absl::string_view lhs,
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absl::string_view rhs) const {
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return compare_internal::compare_result_as_ordering(lhs.compare(rhs));
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}
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};
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struct StringBtreeDefaultGreater {
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using is_transparent = void;
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StringBtreeDefaultGreater() = default;
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StringBtreeDefaultGreater(std::greater<std::string>) {} // NOLINT
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StringBtreeDefaultGreater(std::greater<string_view>) {} // NOLINT
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absl::weak_ordering operator()(absl::string_view lhs,
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absl::string_view rhs) const {
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return compare_internal::compare_result_as_ordering(rhs.compare(lhs));
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}
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};
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// A helper class to convert a boolean comparison into a three-way "compare-to"
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// comparison that returns a negative value to indicate less-than, zero to
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// indicate equality and a positive value to indicate greater-than. This helper
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// class is specialized for less<std::string>, greater<std::string>,
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// less<string_view>, and greater<string_view>.
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//
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// key_compare_to_adapter is provided so that btree users
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// automatically get the more efficient compare-to code when using common
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// google string types with common comparison functors.
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// These string-like specializations also turn on heterogeneous lookup by
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// default.
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template <typename Compare>
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struct key_compare_to_adapter {
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using type = Compare;
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};
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template <>
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struct key_compare_to_adapter<std::less<std::string>> {
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using type = StringBtreeDefaultLess;
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};
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template <>
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struct key_compare_to_adapter<std::greater<std::string>> {
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using type = StringBtreeDefaultGreater;
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};
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template <>
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struct key_compare_to_adapter<std::less<absl::string_view>> {
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using type = StringBtreeDefaultLess;
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};
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template <>
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struct key_compare_to_adapter<std::greater<absl::string_view>> {
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using type = StringBtreeDefaultGreater;
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};
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template <typename Key, typename Compare, typename Alloc, int TargetNodeSize,
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bool Multi, typename SlotPolicy>
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struct common_params {
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// If Compare is a common comparator for a std::string-like type, then we adapt it
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// to use heterogeneous lookup and to be a key-compare-to comparator.
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using key_compare = typename key_compare_to_adapter<Compare>::type;
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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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using is_key_compare_to = btree_is_key_compare_to<key_compare, Key>;
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using allocator_type = Alloc;
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using key_type = Key;
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using size_type = std::make_signed<size_t>::type;
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using difference_type = ptrdiff_t;
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// True if this is a multiset or multimap.
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using is_multi_container = std::integral_constant<bool, Multi>;
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using slot_policy = SlotPolicy;
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using slot_type = typename slot_policy::slot_type;
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using value_type = typename slot_policy::value_type;
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using init_type = typename slot_policy::mutable_value_type;
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using pointer = value_type *;
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using const_pointer = const value_type *;
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using reference = value_type &;
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using const_reference = const value_type &;
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enum {
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kTargetNodeSize = TargetNodeSize,
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// Upper bound for the available space for values. This is largest for leaf
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// nodes, which have overhead of at least a pointer + 4 bytes (for storing
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// 3 field_types and an enum).
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kNodeValueSpace =
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TargetNodeSize - /*minimum overhead=*/(sizeof(void *) + 4),
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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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using node_count_type =
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absl::conditional_t<(kNodeValueSpace / sizeof(value_type) >
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(std::numeric_limits<uint8_t>::max)()),
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uint16_t, uint8_t>; // NOLINT
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// The following methods are necessary for passing this struct as PolicyTraits
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// for node_handle and/or are used within btree.
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static value_type &element(slot_type *slot) {
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return slot_policy::element(slot);
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}
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static const value_type &element(const slot_type *slot) {
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return slot_policy::element(slot);
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}
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template <class... Args>
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static void construct(Alloc *alloc, slot_type *slot, Args &&... args) {
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slot_policy::construct(alloc, slot, std::forward<Args>(args)...);
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}
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static void construct(Alloc *alloc, slot_type *slot, slot_type *other) {
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slot_policy::construct(alloc, slot, other);
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}
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static void destroy(Alloc *alloc, slot_type *slot) {
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slot_policy::destroy(alloc, slot);
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}
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static void transfer(Alloc *alloc, slot_type *new_slot, slot_type *old_slot) {
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construct(alloc, new_slot, old_slot);
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destroy(alloc, old_slot);
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}
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static void swap(Alloc *alloc, slot_type *a, slot_type *b) {
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slot_policy::swap(alloc, a, b);
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}
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static void move(Alloc *alloc, slot_type *src, slot_type *dest) {
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slot_policy::move(alloc, src, dest);
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}
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static void move(Alloc *alloc, slot_type *first, slot_type *last,
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slot_type *result) {
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slot_policy::move(alloc, first, last, result);
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}
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};
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// A parameters structure for holding the type parameters for a btree_map.
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// Compare and Alloc should be nothrow copy-constructible.
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template <typename Key, typename Data, typename Compare, typename Alloc,
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int TargetNodeSize, bool Multi>
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struct map_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi,
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map_slot_policy<Key, Data>> {
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using super_type = typename map_params::common_params;
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using mapped_type = Data;
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// This type allows us to move keys when it is safe to do so. It is safe
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// for maps in which value_type and mutable_value_type are layout compatible.
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using slot_policy = typename super_type::slot_policy;
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using slot_type = typename super_type::slot_type;
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using value_type = typename super_type::value_type;
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using init_type = typename super_type::init_type;
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using key_compare = typename super_type::key_compare;
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// Inherit from key_compare for empty base class optimization.
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struct value_compare : private key_compare {
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value_compare() = default;
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explicit value_compare(const key_compare &cmp) : key_compare(cmp) {}
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template <typename T, typename U>
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auto operator()(const T &left, const U &right) const
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-> decltype(std::declval<key_compare>()(left.first, right.first)) {
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return key_compare::operator()(left.first, right.first);
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}
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};
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using is_map_container = std::true_type;
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static const Key &key(const value_type &x) { return x.first; }
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static const Key &key(const init_type &x) { return x.first; }
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static const Key &key(const slot_type *x) { return slot_policy::key(x); }
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static mapped_type &value(value_type *value) { return value->second; }
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};
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// This type implements the necessary functions from the
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// absl::container_internal::slot_type interface.
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template <typename Key>
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struct set_slot_policy {
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using slot_type = Key;
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using value_type = Key;
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using mutable_value_type = Key;
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static value_type &element(slot_type *slot) { return *slot; }
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static const value_type &element(const slot_type *slot) { return *slot; }
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template <typename Alloc, class... Args>
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static void construct(Alloc *alloc, slot_type *slot, Args &&... args) {
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absl::allocator_traits<Alloc>::construct(*alloc, slot,
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std::forward<Args>(args)...);
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}
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template <typename Alloc>
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static void construct(Alloc *alloc, slot_type *slot, slot_type *other) {
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absl::allocator_traits<Alloc>::construct(*alloc, slot, std::move(*other));
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}
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template <typename Alloc>
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static void destroy(Alloc *alloc, slot_type *slot) {
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absl::allocator_traits<Alloc>::destroy(*alloc, slot);
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}
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template <typename Alloc>
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static void swap(Alloc * /*alloc*/, slot_type *a, slot_type *b) {
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using std::swap;
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swap(*a, *b);
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}
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template <typename Alloc>
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static void move(Alloc * /*alloc*/, slot_type *src, slot_type *dest) {
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*dest = std::move(*src);
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}
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template <typename Alloc>
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static void move(Alloc *alloc, slot_type *first, slot_type *last,
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slot_type *result) {
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for (slot_type *src = first, *dest = result; src != last; ++src, ++dest)
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move(alloc, src, dest);
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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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// Compare and Alloc should be nothrow copy-constructible.
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template <typename Key, typename Compare, typename Alloc, int TargetNodeSize,
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bool Multi>
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struct set_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi,
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set_slot_policy<Key>> {
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using value_type = Key;
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using slot_type = typename set_params::common_params::slot_type;
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using value_compare = typename set_params::common_params::key_compare;
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using is_map_container = std::false_type;
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static const Key &key(const value_type &x) { return x; }
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static const Key &key(const slot_type *x) { return *x; }
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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. Note: there is no need to make a version of this adapter specialized
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// for key-compare-to functors because the upper-bound (the first value greater
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// than the input) is never an exact match.
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template <typename Compare>
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struct upper_bound_adapter {
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explicit upper_bound_adapter(const Compare &c) : comp(c) {}
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template <typename K, typename LK>
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bool operator()(const K &a, const LK &b) const {
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// Returns true when a is not greater than b.
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return !compare_internal::compare_result_as_less_than(comp(b, a));
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}
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private:
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Compare comp;
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};
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enum class MatchKind : uint8_t { kEq, kNe };
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template <typename V, bool IsCompareTo>
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struct SearchResult {
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V value;
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MatchKind match;
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static constexpr bool HasMatch() { return true; }
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bool IsEq() const { return match == MatchKind::kEq; }
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};
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// When we don't use CompareTo, `match` is not present.
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// This ensures that callers can't use it accidentally when it provides no
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// useful information.
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template <typename V>
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struct SearchResult<V, false> {
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V value;
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static constexpr bool HasMatch() { return false; }
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static constexpr bool IsEq() { return false; }
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};
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// A node in the btree holding. The same node type is used for both internal
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// and leaf nodes in the btree, though the nodes are allocated in such a way
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// that the children array is only valid in internal nodes.
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template <typename Params>
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class btree_node {
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using is_key_compare_to = typename Params::is_key_compare_to;
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using is_multi_container = typename Params::is_multi_container;
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using field_type = typename Params::node_count_type;
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using allocator_type = typename Params::allocator_type;
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using slot_type = typename Params::slot_type;
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public:
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using params_type = Params;
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using key_type = typename Params::key_type;
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using value_type = typename Params::value_type;
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using pointer = typename Params::pointer;
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using const_pointer = typename Params::const_pointer;
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using reference = typename Params::reference;
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using const_reference = typename Params::const_reference;
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using key_compare = typename Params::key_compare;
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using size_type = typename Params::size_type;
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using difference_type = typename Params::difference_type;
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// Btree decides whether to use linear node search as follows:
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// - If the key is arithmetic and the comparator is std::less or
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// std::greater, choose linear.
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// - Otherwise, choose binary.
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// TODO(ezb): Might make sense to add condition(s) based on node-size.
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using use_linear_search = std::integral_constant<
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bool,
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std::is_arithmetic<key_type>::value &&
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(std::is_same<std::less<key_type>, key_compare>::value ||
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std::is_same<std::greater<key_type>, key_compare>::value)>;
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// This class is organized by gtl::Layout as if it had the following
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// structure:
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// // A pointer to the node's parent.
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// btree_node *parent;
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//
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// // The position of the node in the node's parent.
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// field_type position;
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// // The index of the first populated value in `values`.
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// // TODO(ezb): right now, `start` is always 0. Update insertion/merge
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// // logic to allow for floating storage within nodes.
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// field_type start;
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// // The count of the number of populated values in the node.
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// field_type count;
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// // The maximum number of values the node can hold. This is an integer in
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// // [1, kNodeValues] for root leaf nodes, kNodeValues for non-root leaf
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// // nodes, and kInternalNodeMaxCount (as a sentinel value) for internal
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// // nodes (even though there are still kNodeValues values in the node).
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// // TODO(ezb): make max_count use only 4 bits and record log2(capacity)
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// // to free extra bits for is_root, etc.
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// field_type max_count;
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//
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// // The array of values. The capacity is `max_count` for leaf nodes and
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// // kNodeValues for internal nodes. Only the values in
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// // [start, start + count) have been initialized and are valid.
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// slot_type values[max_count];
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//
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// // The array of child pointers. The keys in children[i] are all less
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// // than key(i). The keys in children[i + 1] are all greater than key(i).
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// // There are 0 children for leaf nodes and kNodeValues + 1 children for
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// // internal nodes.
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// btree_node *children[kNodeValues + 1];
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//
|
|
// This class is only constructed by EmptyNodeType. Normally, pointers to the
|
|
// layout above are allocated, cast to btree_node*, and de-allocated within
|
|
// the btree implementation.
|
|
~btree_node() = default;
|
|
btree_node(btree_node const &) = delete;
|
|
btree_node &operator=(btree_node const &) = delete;
|
|
|
|
// Public for EmptyNodeType.
|
|
constexpr static size_type Alignment() {
|
|
static_assert(LeafLayout(1).Alignment() == InternalLayout().Alignment(),
|
|
"Alignment of all nodes must be equal.");
|
|
return InternalLayout().Alignment();
|
|
}
|
|
|
|
protected:
|
|
btree_node() = default;
|
|
|
|
private:
|
|
using layout_type = absl::container_internal::Layout<btree_node *, field_type,
|
|
slot_type, btree_node *>;
|
|
constexpr static size_type SizeWithNValues(size_type n) {
|
|
return layout_type(/*parent*/ 1,
|
|
/*position, start, count, max_count*/ 4,
|
|
/*values*/ n,
|
|
/*children*/ 0)
|
|
.AllocSize();
|
|
}
|
|
// A lower bound for the overhead of fields other than values in a leaf node.
|
|
constexpr static size_type MinimumOverhead() {
|
|
return SizeWithNValues(1) - sizeof(value_type);
|
|
}
|
|
|
|
// Compute how many values we can fit onto a leaf node taking into account
|
|
// padding.
|
|
constexpr static size_type NodeTargetValues(const int begin, const int end) {
|
|
return begin == end ? begin
|
|
: SizeWithNValues((begin + end) / 2 + 1) >
|
|
params_type::kTargetNodeSize
|
|
? NodeTargetValues(begin, (begin + end) / 2)
|
|
: NodeTargetValues((begin + end) / 2 + 1, end);
|
|
}
|
|
|
|
enum {
|
|
kTargetNodeSize = params_type::kTargetNodeSize,
|
|
kNodeTargetValues = NodeTargetValues(0, params_type::kTargetNodeSize),
|
|
|
|
// 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,
|
|
|
|
// The node is internal (i.e. is not a leaf node) if and only if `max_count`
|
|
// has this value.
|
|
kInternalNodeMaxCount = 0,
|
|
};
|
|
|
|
// Leaves can have less than kNodeValues values.
|
|
constexpr static layout_type LeafLayout(const int max_values = kNodeValues) {
|
|
return layout_type(/*parent*/ 1,
|
|
/*position, start, count, max_count*/ 4,
|
|
/*values*/ max_values,
|
|
/*children*/ 0);
|
|
}
|
|
constexpr static layout_type InternalLayout() {
|
|
return layout_type(/*parent*/ 1,
|
|
/*position, start, count, max_count*/ 4,
|
|
/*values*/ kNodeValues,
|
|
/*children*/ kNodeValues + 1);
|
|
}
|
|
constexpr static size_type LeafSize(const int max_values = kNodeValues) {
|
|
return LeafLayout(max_values).AllocSize();
|
|
}
|
|
constexpr static size_type InternalSize() {
|
|
return InternalLayout().AllocSize();
|
|
}
|
|
|
|
// N is the index of the type in the Layout definition.
|
|
// ElementType<N> is the Nth type in the Layout definition.
|
|
template <size_type N>
|
|
inline typename layout_type::template ElementType<N> *GetField() {
|
|
// We assert that we don't read from values that aren't there.
|
|
assert(N < 3 || !leaf());
|
|
return InternalLayout().template Pointer<N>(reinterpret_cast<char *>(this));
|
|
}
|
|
template <size_type N>
|
|
inline const typename layout_type::template ElementType<N> *GetField() const {
|
|
assert(N < 3 || !leaf());
|
|
return InternalLayout().template Pointer<N>(
|
|
reinterpret_cast<const char *>(this));
|
|
}
|
|
void set_parent(btree_node *p) { *GetField<0>() = p; }
|
|
field_type &mutable_count() { return GetField<1>()[2]; }
|
|
slot_type *slot(int i) { return &GetField<2>()[i]; }
|
|
const slot_type *slot(int i) const { return &GetField<2>()[i]; }
|
|
void set_position(field_type v) { GetField<1>()[0] = v; }
|
|
void set_start(field_type v) { GetField<1>()[1] = v; }
|
|
void set_count(field_type v) { GetField<1>()[2] = v; }
|
|
// This method is only called by the node init methods.
|
|
void set_max_count(field_type v) { GetField<1>()[3] = v; }
|
|
|
|
public:
|
|
// Whether this is a leaf node or not. This value doesn't change after the
|
|
// node is created.
|
|
bool leaf() const { return GetField<1>()[3] != kInternalNodeMaxCount; }
|
|
|
|
// Getter for the position of this node in its parent.
|
|
field_type position() const { return GetField<1>()[0]; }
|
|
|
|
// Getter for the offset of the first value in the `values` array.
|
|
field_type start() const { return GetField<1>()[1]; }
|
|
|
|
// Getters for the number of values stored in this node.
|
|
field_type count() const { return GetField<1>()[2]; }
|
|
field_type max_count() const {
|
|
// Internal nodes have max_count==kInternalNodeMaxCount.
|
|
// Leaf nodes have max_count in [1, kNodeValues].
|
|
const field_type max_count = GetField<1>()[3];
|
|
return max_count == field_type{kInternalNodeMaxCount}
|
|
? field_type{kNodeValues}
|
|
: max_count;
|
|
}
|
|
|
|
// Getter for the parent of this node.
|
|
btree_node *parent() const { return *GetField<0>(); }
|
|
// 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());
|
|
set_parent(parent()->parent());
|
|
}
|
|
|
|
// Getters for the key/value at position i in the node.
|
|
const key_type &key(int i) const { return params_type::key(slot(i)); }
|
|
reference value(int i) { return params_type::element(slot(i)); }
|
|
const_reference value(int i) const { return params_type::element(slot(i)); }
|
|
|
|
// Getters/setter for the child at position i in the node.
|
|
btree_node *child(int i) const { return GetField<3>()[i]; }
|
|
btree_node *&mutable_child(int i) { return GetField<3>()[i]; }
|
|
void clear_child(int i) {
|
|
absl::container_internal::SanitizerPoisonObject(&mutable_child(i));
|
|
}
|
|
void set_child(int i, btree_node *c) {
|
|
absl::container_internal::SanitizerUnpoisonObject(&mutable_child(i));
|
|
mutable_child(i) = c;
|
|
c->set_position(i);
|
|
}
|
|
void init_child(int i, btree_node *c) {
|
|
set_child(i, c);
|
|
c->set_parent(this);
|
|
}
|
|
|
|
// Returns the position of the first value whose key is not less than k.
|
|
template <typename K>
|
|
SearchResult<int, is_key_compare_to::value> lower_bound(
|
|
const K &k, const key_compare &comp) const {
|
|
return use_linear_search::value ? linear_search(k, comp)
|
|
: binary_search(k, comp);
|
|
}
|
|
// Returns the position of the first value whose key is greater than k.
|
|
template <typename K>
|
|
int upper_bound(const K &k, const key_compare &comp) const {
|
|
auto upper_compare = upper_bound_adapter<key_compare>(comp);
|
|
return use_linear_search::value ? linear_search(k, upper_compare).value
|
|
: binary_search(k, upper_compare).value;
|
|
}
|
|
|
|
template <typename K, typename Compare>
|
|
SearchResult<int, btree_is_key_compare_to<Compare, key_type>::value>
|
|
linear_search(const K &k, const Compare &comp) const {
|
|
return linear_search_impl(k, 0, count(), comp,
|
|
btree_is_key_compare_to<Compare, key_type>());
|
|
}
|
|
|
|
template <typename K, typename Compare>
|
|
SearchResult<int, btree_is_key_compare_to<Compare, key_type>::value>
|
|
binary_search(const K &k, const Compare &comp) const {
|
|
return binary_search_impl(k, 0, count(), comp,
|
|
btree_is_key_compare_to<Compare, key_type>());
|
|
}
|
|
|
|
// Returns the position of the first value whose key is not less than k using
|
|
// linear search performed using plain compare.
|
|
template <typename K, typename Compare>
|
|
SearchResult<int, false> linear_search_impl(
|
|
const K &k, int s, const int e, const Compare &comp,
|
|
std::false_type /* IsCompareTo */) const {
|
|
while (s < e) {
|
|
if (!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 K, typename Compare>
|
|
SearchResult<int, true> linear_search_impl(
|
|
const K &k, int s, const int e, const Compare &comp,
|
|
std::true_type /* IsCompareTo */) const {
|
|
while (s < e) {
|
|
const absl::weak_ordering c = comp(key(s), k);
|
|
if (c == 0) {
|
|
return {s, MatchKind::kEq};
|
|
} else if (c > 0) {
|
|
break;
|
|
}
|
|
++s;
|
|
}
|
|
return {s, MatchKind::kNe};
|
|
}
|
|
|
|
// Returns the position of the first value whose key is not less than k using
|
|
// binary search performed using plain compare.
|
|
template <typename K, typename Compare>
|
|
SearchResult<int, false> binary_search_impl(
|
|
const K &k, int s, int e, const Compare &comp,
|
|
std::false_type /* IsCompareTo */) const {
|
|
while (s != e) {
|
|
const int mid = (s + e) >> 1;
|
|
if (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 K, typename CompareTo>
|
|
SearchResult<int, true> binary_search_impl(
|
|
const K &k, int s, int e, const CompareTo &comp,
|
|
std::true_type /* IsCompareTo */) const {
|
|
if (is_multi_container::value) {
|
|
MatchKind exact_match = MatchKind::kNe;
|
|
while (s != e) {
|
|
const int mid = (s + e) >> 1;
|
|
const absl::weak_ordering c = comp(key(mid), k);
|
|
if (c < 0) {
|
|
s = mid + 1;
|
|
} else {
|
|
e = mid;
|
|
if (c == 0) {
|
|
// Need to return the first value whose key is not less than k,
|
|
// which requires continuing the binary search if this is a
|
|
// multi-container.
|
|
exact_match = MatchKind::kEq;
|
|
}
|
|
}
|
|
}
|
|
return {s, exact_match};
|
|
} else { // Not a multi-container.
|
|
while (s != e) {
|
|
const int mid = (s + e) >> 1;
|
|
const absl::weak_ordering c = comp(key(mid), k);
|
|
if (c < 0) {
|
|
s = mid + 1;
|
|
} else if (c > 0) {
|
|
e = mid;
|
|
} else {
|
|
return {mid, MatchKind::kEq};
|
|
}
|
|
}
|
|
return {s, MatchKind::kNe};
|
|
}
|
|
}
|
|
|
|
// Emplaces a value at position i, shifting all existing values and
|
|
// children at positions >= i to the right by 1.
|
|
template <typename... Args>
|
|
void emplace_value(size_type i, allocator_type *alloc, Args &&... args);
|
|
|
|
// Removes the value at position i, shifting all existing values and children
|
|
// at positions > i to the left by 1.
|
|
void remove_value(int i, allocator_type *alloc);
|
|
|
|
// Removes the values at positions [i, i + to_erase), shifting all values
|
|
// after that range to the left by to_erase. Does not change children at all.
|
|
void remove_values_ignore_children(int i, int to_erase,
|
|
allocator_type *alloc);
|
|
|
|
// Rebalances a node with its right sibling.
|
|
void rebalance_right_to_left(int to_move, btree_node *right,
|
|
allocator_type *alloc);
|
|
void rebalance_left_to_right(int to_move, btree_node *right,
|
|
allocator_type *alloc);
|
|
|
|
// Splits a node, moving a portion of the node's values to its right sibling.
|
|
void split(int insert_position, btree_node *dest, allocator_type *alloc);
|
|
|
|
// Merges a node with its right sibling, moving all of the values and the
|
|
// delimiting key in the parent node onto itself.
|
|
void merge(btree_node *sibling, allocator_type *alloc);
|
|
|
|
// Swap the contents of "this" and "src".
|
|
void swap(btree_node *src, allocator_type *alloc);
|
|
|
|
// Node allocation/deletion routines.
|
|
static btree_node *init_leaf(btree_node *n, btree_node *parent,
|
|
int max_count) {
|
|
n->set_parent(parent);
|
|
n->set_position(0);
|
|
n->set_start(0);
|
|
n->set_count(0);
|
|
n->set_max_count(max_count);
|
|
absl::container_internal::SanitizerPoisonMemoryRegion(
|
|
n->slot(0), max_count * sizeof(slot_type));
|
|
return n;
|
|
}
|
|
static btree_node *init_internal(btree_node *n, btree_node *parent) {
|
|
init_leaf(n, parent, kNodeValues);
|
|
// Set `max_count` to a sentinel value to indicate that this node is
|
|
// internal.
|
|
n->set_max_count(kInternalNodeMaxCount);
|
|
absl::container_internal::SanitizerPoisonMemoryRegion(
|
|
&n->mutable_child(0), (kNodeValues + 1) * sizeof(btree_node *));
|
|
return n;
|
|
}
|
|
void destroy(allocator_type *alloc) {
|
|
for (int i = 0; i < count(); ++i) {
|
|
value_destroy(i, alloc);
|
|
}
|
|
}
|
|
|
|
public:
|
|
// Exposed only for tests.
|
|
static bool testonly_uses_linear_node_search() {
|
|
return use_linear_search::value;
|
|
}
|
|
|
|
private:
|
|
template <typename... Args>
|
|
void value_init(const size_type i, allocator_type *alloc, Args &&... args) {
|
|
absl::container_internal::SanitizerUnpoisonObject(slot(i));
|
|
params_type::construct(alloc, slot(i), std::forward<Args>(args)...);
|
|
}
|
|
void value_destroy(const size_type i, allocator_type *alloc) {
|
|
params_type::destroy(alloc, slot(i));
|
|
absl::container_internal::SanitizerPoisonObject(slot(i));
|
|
}
|
|
|
|
// Move n values starting at value i in this node into the values starting at
|
|
// value j in node x.
|
|
void uninitialized_move_n(const size_type n, const size_type i,
|
|
const size_type j, btree_node *x,
|
|
allocator_type *alloc) {
|
|
absl::container_internal::SanitizerUnpoisonMemoryRegion(
|
|
x->slot(j), n * sizeof(slot_type));
|
|
for (slot_type *src = slot(i), *end = src + n, *dest = x->slot(j);
|
|
src != end; ++src, ++dest) {
|
|
params_type::construct(alloc, dest, src);
|
|
}
|
|
}
|
|
|
|
// Destroys a range of n values, starting at index i.
|
|
void value_destroy_n(const size_type i, const size_type n,
|
|
allocator_type *alloc) {
|
|
for (int j = 0; j < n; ++j) {
|
|
value_destroy(i + j, alloc);
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
friend class btree;
|
|
template <typename N, typename R, typename P>
|
|
friend struct btree_iterator;
|
|
friend class BtreeNodePeer;
|
|
};
|
|
|
|
template <typename Node, typename Reference, typename Pointer>
|
|
struct btree_iterator {
|
|
private:
|
|
using key_type = typename Node::key_type;
|
|
using size_type = typename Node::size_type;
|
|
using params_type = typename Node::params_type;
|
|
|
|
using node_type = Node;
|
|
using normal_node = typename std::remove_const<Node>::type;
|
|
using const_node = const Node;
|
|
using normal_pointer = typename params_type::pointer;
|
|
using normal_reference = typename params_type::reference;
|
|
using const_pointer = typename params_type::const_pointer;
|
|
using const_reference = typename params_type::const_reference;
|
|
using slot_type = typename params_type::slot_type;
|
|
|
|
using iterator =
|
|
btree_iterator<normal_node, normal_reference, normal_pointer>;
|
|
using const_iterator =
|
|
btree_iterator<const_node, const_reference, const_pointer>;
|
|
|
|
public:
|
|
// These aliases are public for std::iterator_traits.
|
|
using difference_type = typename Node::difference_type;
|
|
using value_type = typename params_type::value_type;
|
|
using pointer = Pointer;
|
|
using reference = Reference;
|
|
using iterator_category = std::bidirectional_iterator_tag;
|
|
|
|
btree_iterator() : node(nullptr), position(-1) {}
|
|
btree_iterator(Node *n, int p) : node(n), position(p) {}
|
|
|
|
// NOTE: this SFINAE allows for implicit conversions from iterator to
|
|
// const_iterator, but it specifically avoids defining copy constructors so
|
|
// that btree_iterator can be trivially copyable. This is for performance and
|
|
// binary size reasons.
|
|
template <typename N, typename R, typename P,
|
|
absl::enable_if_t<
|
|
std::is_same<btree_iterator<N, R, P>, iterator>::value &&
|
|
std::is_same<btree_iterator, const_iterator>::value,
|
|
int> = 0>
|
|
btree_iterator(const btree_iterator<N, R, P> &x) // NOLINT
|
|
: node(x.node), position(x.position) {}
|
|
|
|
private:
|
|
// This SFINAE allows explicit conversions from const_iterator to
|
|
// iterator, but also avoids defining a copy constructor.
|
|
// NOTE: the const_cast is safe because this constructor is only called by
|
|
// non-const methods and the container owns the nodes.
|
|
template <typename N, typename R, typename P,
|
|
absl::enable_if_t<
|
|
std::is_same<btree_iterator<N, R, P>, const_iterator>::value &&
|
|
std::is_same<btree_iterator, iterator>::value,
|
|
int> = 0>
|
|
explicit btree_iterator(const btree_iterator<N, R, P> &x)
|
|
: node(const_cast<node_type *>(x.node)), position(x.position) {}
|
|
|
|
// Increment/decrement the iterator.
|
|
void increment() {
|
|
if (node->leaf() && ++position < node->count()) {
|
|
return;
|
|
}
|
|
increment_slow();
|
|
}
|
|
void increment_slow();
|
|
|
|
void decrement() {
|
|
if (node->leaf() && --position >= 0) {
|
|
return;
|
|
}
|
|
decrement_slow();
|
|
}
|
|
void decrement_slow();
|
|
|
|
public:
|
|
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.
|
|
reference operator*() const {
|
|
return node->value(position);
|
|
}
|
|
pointer operator->() const {
|
|
return &node->value(position);
|
|
}
|
|
|
|
btree_iterator& operator++() {
|
|
increment();
|
|
return *this;
|
|
}
|
|
btree_iterator& operator--() {
|
|
decrement();
|
|
return *this;
|
|
}
|
|
btree_iterator operator++(int) {
|
|
btree_iterator tmp = *this;
|
|
++*this;
|
|
return tmp;
|
|
}
|
|
btree_iterator operator--(int) {
|
|
btree_iterator tmp = *this;
|
|
--*this;
|
|
return tmp;
|
|
}
|
|
|
|
private:
|
|
template <typename Params>
|
|
friend class btree;
|
|
template <typename Tree>
|
|
friend class btree_container;
|
|
template <typename Tree>
|
|
friend class btree_set_container;
|
|
template <typename Tree>
|
|
friend class btree_map_container;
|
|
template <typename Tree>
|
|
friend class btree_multiset_container;
|
|
template <typename N, typename R, typename P>
|
|
friend struct btree_iterator;
|
|
template <typename TreeType, typename CheckerType>
|
|
friend class base_checker;
|
|
|
|
const key_type &key() const { return node->key(position); }
|
|
slot_type *slot() { return node->slot(position); }
|
|
|
|
// The node in the tree the iterator is pointing at.
|
|
Node *node;
|
|
// The position within the node of the tree the iterator is pointing at.
|
|
// TODO(ezb): make this a field_type
|
|
int position;
|
|
};
|
|
|
|
template <typename Params>
|
|
class btree {
|
|
using node_type = btree_node<Params>;
|
|
using is_key_compare_to = typename Params::is_key_compare_to;
|
|
|
|
// We use a static empty node for the root/leftmost/rightmost of empty btrees
|
|
// in order to avoid branching in begin()/end().
|
|
struct alignas(node_type::Alignment()) EmptyNodeType : node_type {
|
|
using field_type = typename node_type::field_type;
|
|
node_type *parent;
|
|
field_type position = 0;
|
|
field_type start = 0;
|
|
field_type count = 0;
|
|
// max_count must be != kInternalNodeMaxCount (so that this node is regarded
|
|
// as a leaf node). max_count() is never called when the tree is empty.
|
|
field_type max_count = node_type::kInternalNodeMaxCount + 1;
|
|
|
|
#ifdef _MSC_VER
|
|
// MSVC has constexpr code generations bugs here.
|
|
EmptyNodeType() : parent(this) {}
|
|
#else
|
|
constexpr EmptyNodeType(node_type *p) : parent(p) {}
|
|
#endif
|
|
};
|
|
|
|
static node_type *EmptyNode() {
|
|
#ifdef _MSC_VER
|
|
static EmptyNodeType* empty_node = new EmptyNodeType;
|
|
// This assert fails on some other construction methods.
|
|
assert(empty_node->parent == empty_node);
|
|
return empty_node;
|
|
#else
|
|
static constexpr EmptyNodeType empty_node(
|
|
const_cast<EmptyNodeType *>(&empty_node));
|
|
return const_cast<EmptyNodeType *>(&empty_node);
|
|
#endif
|
|
}
|
|
|
|
enum {
|
|
kNodeValues = node_type::kNodeValues,
|
|
kMinNodeValues = kNodeValues / 2,
|
|
};
|
|
|
|
struct node_stats {
|
|
using size_type = typename Params::size_type;
|
|
|
|
node_stats(size_type l, size_type i)
|
|
: leaf_nodes(l),
|
|
internal_nodes(i) {
|
|
}
|
|
|
|
node_stats& operator+=(const node_stats &x) {
|
|
leaf_nodes += x.leaf_nodes;
|
|
internal_nodes += x.internal_nodes;
|
|
return *this;
|
|
}
|
|
|
|
size_type leaf_nodes;
|
|
size_type internal_nodes;
|
|
};
|
|
|
|
public:
|
|
using key_type = typename Params::key_type;
|
|
using value_type = typename Params::value_type;
|
|
using size_type = typename Params::size_type;
|
|
using difference_type = typename Params::difference_type;
|
|
using key_compare = typename Params::key_compare;
|
|
using value_compare = typename Params::value_compare;
|
|
using allocator_type = typename Params::allocator_type;
|
|
using reference = typename Params::reference;
|
|
using const_reference = typename Params::const_reference;
|
|
using pointer = typename Params::pointer;
|
|
using const_pointer = typename Params::const_pointer;
|
|
using iterator = btree_iterator<node_type, reference, pointer>;
|
|
using const_iterator = typename iterator::const_iterator;
|
|
using reverse_iterator = std::reverse_iterator<iterator>;
|
|
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
|
|
using node_handle_type = node_handle<Params, Params, allocator_type>;
|
|
|
|
// Internal types made public for use by btree_container types.
|
|
using params_type = Params;
|
|
using slot_type = typename Params::slot_type;
|
|
|
|
private:
|
|
// For use in copy_or_move_values_in_order.
|
|
const value_type &maybe_move_from_iterator(const_iterator x) { return *x; }
|
|
value_type &&maybe_move_from_iterator(iterator x) { return std::move(*x); }
|
|
|
|
// Copies or moves (depending on the template parameter) the values in
|
|
// x into this btree in their order in x. This btree must be empty before this
|
|
// method is called. This method is used in copy construction, copy
|
|
// assignment, and move assignment.
|
|
template <typename Btree>
|
|
void copy_or_move_values_in_order(Btree *x);
|
|
|
|
// Validates that various assumptions/requirements are true at compile time.
|
|
constexpr static bool static_assert_validation();
|
|
|
|
public:
|
|
btree(const key_compare &comp, const allocator_type &alloc);
|
|
|
|
btree(const btree &x);
|
|
btree(btree &&x) noexcept
|
|
: root_(std::move(x.root_)),
|
|
rightmost_(absl::exchange(x.rightmost_, EmptyNode())),
|
|
size_(absl::exchange(x.size_, 0)) {
|
|
x.mutable_root() = EmptyNode();
|
|
}
|
|
|
|
~btree() {
|
|
// Put static_asserts in destructor to avoid triggering them before the type
|
|
// is complete.
|
|
static_assert(static_assert_validation(), "This call must be elided.");
|
|
clear();
|
|
}
|
|
|
|
// Assign the contents of x to *this.
|
|
btree &operator=(const btree &x);
|
|
btree &operator=(btree &&x) noexcept;
|
|
|
|
iterator begin() {
|
|
return iterator(leftmost(), 0);
|
|
}
|
|
const_iterator begin() const {
|
|
return const_iterator(leftmost(), 0);
|
|
}
|
|
iterator end() { return iterator(rightmost_, rightmost_->count()); }
|
|
const_iterator end() const {
|
|
return const_iterator(rightmost_, rightmost_->count());
|
|
}
|
|
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.
|
|
template <typename K>
|
|
iterator lower_bound(const K &key) {
|
|
return internal_end(internal_lower_bound(key));
|
|
}
|
|
template <typename K>
|
|
const_iterator lower_bound(const K &key) const {
|
|
return internal_end(internal_lower_bound(key));
|
|
}
|
|
|
|
// Finds the first element whose key is greater than key.
|
|
template <typename K>
|
|
iterator upper_bound(const K &key) {
|
|
return internal_end(internal_upper_bound(key));
|
|
}
|
|
template <typename K>
|
|
const_iterator upper_bound(const K &key) const {
|
|
return internal_end(internal_upper_bound(key));
|
|
}
|
|
|
|
// 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).
|
|
template <typename K>
|
|
std::pair<iterator, iterator> equal_range(const K &key) {
|
|
return {lower_bound(key), upper_bound(key)};
|
|
}
|
|
template <typename K>
|
|
std::pair<const_iterator, const_iterator> equal_range(const K &key) const {
|
|
return {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.
|
|
// Requirement: if `key` already exists in the btree, does not consume `args`.
|
|
// Requirement: `key` is never referenced after consuming `args`.
|
|
template <typename... Args>
|
|
std::pair<iterator, bool> insert_unique(const key_type &key, Args &&... args);
|
|
|
|
// Inserts with hint. Checks to see if the value should be placed immediately
|
|
// before `position` in the tree. If so, then the insertion will take
|
|
// amortized constant time. If not, the insertion will take amortized
|
|
// logarithmic time as if a call to insert_unique() were made.
|
|
// Requirement: if `key` already exists in the btree, does not consume `args`.
|
|
// Requirement: `key` is never referenced after consuming `args`.
|
|
template <typename... Args>
|
|
std::pair<iterator, bool> insert_hint_unique(iterator position,
|
|
const key_type &key,
|
|
Args &&... args);
|
|
|
|
// Insert a range of values into the btree.
|
|
template <typename InputIterator>
|
|
void insert_iterator_unique(InputIterator b, InputIterator e);
|
|
|
|
// Inserts a value into the btree.
|
|
template <typename ValueType>
|
|
iterator insert_multi(const key_type &key, ValueType &&v);
|
|
|
|
// Inserts a value into the btree.
|
|
template <typename ValueType>
|
|
iterator insert_multi(ValueType &&v) {
|
|
return insert_multi(params_type::key(v), std::forward<ValueType>(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.
|
|
template <typename ValueType>
|
|
iterator insert_hint_multi(iterator position, ValueType &&v);
|
|
|
|
// Insert a range of values into the btree.
|
|
template <typename InputIterator>
|
|
void insert_iterator_multi(InputIterator b, InputIterator e);
|
|
|
|
// 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).
|
|
// Requirement: does not read the value at `*iter`.
|
|
iterator erase(iterator iter);
|
|
|
|
// Erases range. Returns the number of keys erased and an iterator pointing
|
|
// to the element after the last erased element.
|
|
std::pair<size_type, iterator> erase(iterator begin, iterator end);
|
|
|
|
// Erases the specified key from the btree. Returns 1 if an element was
|
|
// erased and 0 otherwise.
|
|
template <typename K>
|
|
size_type erase_unique(const K &key);
|
|
|
|
// Erases all of the entries matching the specified key from the
|
|
// btree. Returns the number of elements erased.
|
|
template <typename K>
|
|
size_type erase_multi(const K &key);
|
|
|
|
// Finds the iterator corresponding to a key or returns end() if the key is
|
|
// not present.
|
|
template <typename K>
|
|
iterator find(const K &key) {
|
|
return internal_end(internal_find(key));
|
|
}
|
|
template <typename K>
|
|
const_iterator find(const K &key) const {
|
|
return internal_end(internal_find(key));
|
|
}
|
|
|
|
// Returns a count of the number of times the key appears in the btree.
|
|
template <typename K>
|
|
size_type count_unique(const K &key) const {
|
|
const iterator begin = internal_find(key);
|
|
if (begin.node == nullptr) {
|
|
// The key doesn't exist in the tree.
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
// Returns a count of the number of times the key appears in the btree.
|
|
template <typename K>
|
|
size_type count_multi(const K &key) const {
|
|
const auto range = equal_range(key);
|
|
return std::distance(range.first, range.second);
|
|
}
|
|
|
|
// Clear the btree, deleting all of the values it contains.
|
|
void clear();
|
|
|
|
// Swap the contents of *this and x.
|
|
void swap(btree &x);
|
|
|
|
const key_compare &key_comp() const noexcept {
|
|
return root_.template get<0>();
|
|
}
|
|
template <typename K, typename LK>
|
|
bool compare_keys(const K &x, const LK &y) const {
|
|
return compare_internal::compare_result_as_less_than(key_comp()(x, y));
|
|
}
|
|
|
|
value_compare value_comp() const { return value_compare(key_comp()); }
|
|
|
|
// Verifies the structure of the btree.
|
|
void verify() const;
|
|
|
|
// Size routines.
|
|
size_type size() const { return size_; }
|
|
size_type max_size() const { return (std::numeric_limits<size_type>::max)(); }
|
|
bool empty() const { return size_ == 0; }
|
|
|
|
// The height of the btree. An empty tree will have height 0.
|
|
size_type height() const {
|
|
size_type h = 0;
|
|
if (!empty()) {
|
|
// 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) +
|
|
node_type::LeafSize(root()->max_count());
|
|
} else {
|
|
return sizeof(*this) +
|
|
stats.leaf_nodes * node_type::LeafSize() +
|
|
stats.internal_nodes * node_type::InternalSize();
|
|
}
|
|
}
|
|
|
|
// 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 node_type::LeafSize() / (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.
|
|
// Returns 0 for empty trees.
|
|
double fullness() const {
|
|
if (empty()) return 0.0;
|
|
return static_cast<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.
|
|
// Returns 0 for empty trees.
|
|
double overhead() const {
|
|
if (empty()) return 0.0;
|
|
return (bytes_used() - size() * sizeof(value_type)) /
|
|
static_cast<double>(size());
|
|
}
|
|
|
|
// The allocator used by the btree.
|
|
allocator_type get_allocator() const {
|
|
return allocator();
|
|
}
|
|
|
|
private:
|
|
// Internal accessor routines.
|
|
node_type *root() { return root_.template get<2>(); }
|
|
const node_type *root() const { return root_.template get<2>(); }
|
|
node_type *&mutable_root() noexcept { return root_.template get<2>(); }
|
|
key_compare *mutable_key_comp() noexcept { return &root_.template get<0>(); }
|
|
|
|
// The leftmost node is stored as the parent of the root node.
|
|
node_type *leftmost() { return root()->parent(); }
|
|
const node_type *leftmost() const { return root()->parent(); }
|
|
|
|
// Allocator routines.
|
|
allocator_type *mutable_allocator() noexcept {
|
|
return &root_.template get<1>();
|
|
}
|
|
const allocator_type &allocator() const noexcept {
|
|
return root_.template get<1>();
|
|
}
|
|
|
|
// Allocates a correctly aligned node of at least size bytes using the
|
|
// allocator.
|
|
node_type *allocate(const size_type size) {
|
|
return reinterpret_cast<node_type *>(
|
|
absl::container_internal::Allocate<node_type::Alignment()>(
|
|
mutable_allocator(), size));
|
|
}
|
|
|
|
// Node creation/deletion routines.
|
|
node_type* new_internal_node(node_type *parent) {
|
|
node_type *p = allocate(node_type::InternalSize());
|
|
return node_type::init_internal(p, parent);
|
|
}
|
|
node_type* new_leaf_node(node_type *parent) {
|
|
node_type *p = allocate(node_type::LeafSize());
|
|
return node_type::init_leaf(p, parent, kNodeValues);
|
|
}
|
|
node_type *new_leaf_root_node(const int max_count) {
|
|
node_type *p = allocate(node_type::LeafSize(max_count));
|
|
return node_type::init_leaf(p, p, max_count);
|
|
}
|
|
|
|
// Deletion helper routines.
|
|
void erase_same_node(iterator begin, iterator end);
|
|
iterator erase_from_leaf_node(iterator begin, size_type to_erase);
|
|
iterator rebalance_after_delete(iterator iter);
|
|
|
|
// Deallocates a node of a certain size in bytes using the allocator.
|
|
void deallocate(const size_type size, node_type *node) {
|
|
absl::container_internal::Deallocate<node_type::Alignment()>(
|
|
mutable_allocator(), node, size);
|
|
}
|
|
|
|
void delete_internal_node(node_type *node) {
|
|
node->destroy(mutable_allocator());
|
|
deallocate(node_type::InternalSize(), node);
|
|
}
|
|
void delete_leaf_node(node_type *node) {
|
|
node->destroy(mutable_allocator());
|
|
deallocate(node_type::LeafSize(node->max_count()), node);
|
|
}
|
|
|
|
// Rebalances or splits the node iter points to.
|
|
void rebalance_or_split(iterator *iter);
|
|
|
|
// Merges the values of left, right and the delimiting key on their parent
|
|
// onto left, removing the delimiting key and deleting right.
|
|
void merge_nodes(node_type *left, node_type *right);
|
|
|
|
// Tries to merge node with its left or right sibling, and failing that,
|
|
// rebalance with its left or right sibling. Returns true if a merge
|
|
// occurred, at which point it is no longer valid to access node. Returns
|
|
// false if no merging took place.
|
|
bool try_merge_or_rebalance(iterator *iter);
|
|
|
|
// Tries to shrink the height of the tree by 1.
|
|
void try_shrink();
|
|
|
|
iterator internal_end(iterator iter) {
|
|
return iter.node != nullptr ? iter : end();
|
|
}
|
|
const_iterator internal_end(const_iterator iter) const {
|
|
return iter.node != nullptr ? iter : end();
|
|
}
|
|
|
|
// Emplaces a value into the btree immediately before iter. Requires that
|
|
// key(v) <= iter.key() and (--iter).key() <= key(v).
|
|
template <typename... Args>
|
|
iterator internal_emplace(iterator iter, Args &&... args);
|
|
|
|
// Returns an iterator pointing to the first value >= the value "iter" is
|
|
// pointing at. Note that "iter" might be pointing to an invalid location as
|
|
// iter.position == iter.node->count(). This routine simply moves iter up in
|
|
// the tree to a valid location.
|
|
// Requires: iter.node is non-null.
|
|
template <typename IterType>
|
|
static IterType internal_last(IterType iter);
|
|
|
|
// Returns an iterator pointing to the leaf position at which key would
|
|
// reside in the tree. We provide 2 versions of internal_locate. The first
|
|
// version uses a less-than comparator and is incapable of distinguishing when
|
|
// there is an exact match. The second version is for the key-compare-to
|
|
// specialization and distinguishes exact matches. The key-compare-to
|
|
// specialization allows the caller to avoid a subsequent comparison to
|
|
// determine if an exact match was made, which is important for keys with
|
|
// expensive comparison, such as strings.
|
|
template <typename K>
|
|
SearchResult<iterator, is_key_compare_to::value> internal_locate(
|
|
const K &key) const;
|
|
|
|
template <typename K>
|
|
SearchResult<iterator, false> internal_locate_impl(
|
|
const K &key, std::false_type /* IsCompareTo */) const;
|
|
|
|
template <typename K>
|
|
SearchResult<iterator, true> internal_locate_impl(
|
|
const K &key, std::true_type /* IsCompareTo */) const;
|
|
|
|
// Internal routine which implements lower_bound().
|
|
template <typename K>
|
|
iterator internal_lower_bound(const K &key) const;
|
|
|
|
// Internal routine which implements upper_bound().
|
|
template <typename K>
|
|
iterator internal_upper_bound(const K &key) const;
|
|
|
|
// Internal routine which implements find().
|
|
template <typename K>
|
|
iterator internal_find(const K &key) const;
|
|
|
|
// Deletes a node and all of its children.
|
|
void internal_clear(node_type *node);
|
|
|
|
// Verifies the tree structure of node.
|
|
int internal_verify(const node_type *node,
|
|
const key_type *lo, const key_type *hi) const;
|
|
|
|
node_stats internal_stats(const node_type *node) const {
|
|
// The root can be a static empty node.
|
|
if (node == nullptr || (node == root() && empty())) {
|
|
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;
|
|
}
|
|
|
|
public:
|
|
// Exposed only for tests.
|
|
static bool testonly_uses_linear_node_search() {
|
|
return node_type::testonly_uses_linear_node_search();
|
|
}
|
|
|
|
private:
|
|
// We use compressed tuple in order to save space because key_compare and
|
|
// allocator_type are usually empty.
|
|
absl::container_internal::CompressedTuple<key_compare, allocator_type,
|
|
node_type *>
|
|
root_;
|
|
|
|
// A pointer to the rightmost node. Note that the leftmost node is stored as
|
|
// the root's parent.
|
|
node_type *rightmost_;
|
|
|
|
// Number of values.
|
|
size_type size_;
|
|
};
|
|
|
|
////
|
|
// btree_node methods
|
|
template <typename P>
|
|
template <typename... Args>
|
|
inline void btree_node<P>::emplace_value(const size_type i,
|
|
allocator_type *alloc,
|
|
Args &&... args) {
|
|
assert(i <= count());
|
|
// Shift old values to create space for new value and then construct it in
|
|
// place.
|
|
if (i < count()) {
|
|
value_init(count(), alloc, slot(count() - 1));
|
|
for (size_type j = count() - 1; j > i; --j)
|
|
params_type::move(alloc, slot(j - 1), slot(j));
|
|
value_destroy(i, alloc);
|
|
}
|
|
value_init(i, alloc, std::forward<Args>(args)...);
|
|
set_count(count() + 1);
|
|
|
|
if (!leaf() && count() > i + 1) {
|
|
for (int j = count(); j > i + 1; --j) {
|
|
set_child(j, child(j - 1));
|
|
}
|
|
clear_child(i + 1);
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
inline void btree_node<P>::remove_value(const int i, allocator_type *alloc) {
|
|
if (!leaf() && count() > i + 1) {
|
|
assert(child(i + 1)->count() == 0);
|
|
for (size_type j = i + 1; j < count(); ++j) {
|
|
set_child(j, child(j + 1));
|
|
}
|
|
clear_child(count());
|
|
}
|
|
|
|
remove_values_ignore_children(i, /*to_erase=*/1, alloc);
|
|
}
|
|
|
|
template <typename P>
|
|
inline void btree_node<P>::remove_values_ignore_children(
|
|
const int i, const int to_erase, allocator_type *alloc) {
|
|
params_type::move(alloc, slot(i + to_erase), slot(count()), slot(i));
|
|
value_destroy_n(count() - to_erase, to_erase, alloc);
|
|
set_count(count() - to_erase);
|
|
}
|
|
|
|
template <typename P>
|
|
void btree_node<P>::rebalance_right_to_left(const int to_move,
|
|
btree_node *right,
|
|
allocator_type *alloc) {
|
|
assert(parent() == right->parent());
|
|
assert(position() + 1 == right->position());
|
|
assert(right->count() >= count());
|
|
assert(to_move >= 1);
|
|
assert(to_move <= right->count());
|
|
|
|
// 1) Move the delimiting value in the parent to the left node.
|
|
value_init(count(), alloc, parent()->slot(position()));
|
|
|
|
// 2) Move the (to_move - 1) values from the right node to the left node.
|
|
right->uninitialized_move_n(to_move - 1, 0, count() + 1, this, alloc);
|
|
|
|
// 3) Move the new delimiting value to the parent from the right node.
|
|
params_type::move(alloc, right->slot(to_move - 1),
|
|
parent()->slot(position()));
|
|
|
|
// 4) Shift the values in the right node to their correct position.
|
|
params_type::move(alloc, right->slot(to_move), right->slot(right->count()),
|
|
right->slot(0));
|
|
|
|
// 5) Destroy the now-empty to_move entries in the right node.
|
|
right->value_destroy_n(right->count() - to_move, to_move, alloc);
|
|
|
|
if (!leaf()) {
|
|
// Move the child pointers from the right to the left node.
|
|
for (int i = 0; i < to_move; ++i) {
|
|
init_child(count() + i + 1, right->child(i));
|
|
}
|
|
for (int i = 0; i <= right->count() - to_move; ++i) {
|
|
assert(i + to_move <= right->max_count());
|
|
right->init_child(i, right->child(i + to_move));
|
|
right->clear_child(i + to_move);
|
|
}
|
|
}
|
|
|
|
// Fixup the counts on the left and right nodes.
|
|
set_count(count() + to_move);
|
|
right->set_count(right->count() - to_move);
|
|
}
|
|
|
|
template <typename P>
|
|
void btree_node<P>::rebalance_left_to_right(const int to_move,
|
|
btree_node *right,
|
|
allocator_type *alloc) {
|
|
assert(parent() == right->parent());
|
|
assert(position() + 1 == right->position());
|
|
assert(count() >= right->count());
|
|
assert(to_move >= 1);
|
|
assert(to_move <= count());
|
|
|
|
// Values in the right node are shifted to the right to make room for the
|
|
// new to_move values. Then, the delimiting value in the parent and the
|
|
// other (to_move - 1) values in the left node are moved into the right node.
|
|
// Lastly, a new delimiting value is moved from the left node into the
|
|
// parent, and the remaining empty left node entries are destroyed.
|
|
|
|
if (right->count() >= to_move) {
|
|
// The original location of the right->count() values are sufficient to hold
|
|
// the new to_move entries from the parent and left node.
|
|
|
|
// 1) Shift existing values in the right node to their correct positions.
|
|
right->uninitialized_move_n(to_move, right->count() - to_move,
|
|
right->count(), right, alloc);
|
|
for (slot_type *src = right->slot(right->count() - to_move - 1),
|
|
*dest = right->slot(right->count() - 1),
|
|
*end = right->slot(0);
|
|
src >= end; --src, --dest) {
|
|
params_type::move(alloc, src, dest);
|
|
}
|
|
|
|
// 2) Move the delimiting value in the parent to the right node.
|
|
params_type::move(alloc, parent()->slot(position()),
|
|
right->slot(to_move - 1));
|
|
|
|
// 3) Move the (to_move - 1) values from the left node to the right node.
|
|
params_type::move(alloc, slot(count() - (to_move - 1)), slot(count()),
|
|
right->slot(0));
|
|
} else {
|
|
// The right node does not have enough initialized space to hold the new
|
|
// to_move entries, so part of them will move to uninitialized space.
|
|
|
|
// 1) Shift existing values in the right node to their correct positions.
|
|
right->uninitialized_move_n(right->count(), 0, to_move, right, alloc);
|
|
|
|
// 2) Move the delimiting value in the parent to the right node.
|
|
right->value_init(to_move - 1, alloc, parent()->slot(position()));
|
|
|
|
// 3) Move the (to_move - 1) values from the left node to the right node.
|
|
const size_type uninitialized_remaining = to_move - right->count() - 1;
|
|
uninitialized_move_n(uninitialized_remaining,
|
|
count() - uninitialized_remaining, right->count(),
|
|
right, alloc);
|
|
params_type::move(alloc, slot(count() - (to_move - 1)),
|
|
slot(count() - uninitialized_remaining), right->slot(0));
|
|
}
|
|
|
|
// 4) Move the new delimiting value to the parent from the left node.
|
|
params_type::move(alloc, slot(count() - to_move), parent()->slot(position()));
|
|
|
|
// 5) Destroy the now-empty to_move entries in the left node.
|
|
value_destroy_n(count() - to_move, to_move, alloc);
|
|
|
|
if (!leaf()) {
|
|
// Move the child pointers from the left to the right node.
|
|
for (int i = right->count(); i >= 0; --i) {
|
|
right->init_child(i + to_move, right->child(i));
|
|
right->clear_child(i);
|
|
}
|
|
for (int i = 1; i <= to_move; ++i) {
|
|
right->init_child(i - 1, child(count() - to_move + i));
|
|
clear_child(count() - to_move + i);
|
|
}
|
|
}
|
|
|
|
// Fixup the counts on the left and right nodes.
|
|
set_count(count() - to_move);
|
|
right->set_count(right->count() + to_move);
|
|
}
|
|
|
|
template <typename P>
|
|
void btree_node<P>::split(const int insert_position, btree_node *dest,
|
|
allocator_type *alloc) {
|
|
assert(dest->count() == 0);
|
|
assert(max_count() == kNodeValues);
|
|
|
|
// 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 == kNodeValues) {
|
|
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.
|
|
uninitialized_move_n(dest->count(), count(), 0, dest, alloc);
|
|
|
|
// Destroy the now-empty entries in the left node.
|
|
value_destroy_n(count(), dest->count(), alloc);
|
|
|
|
// The split key is the largest value in the left sibling.
|
|
set_count(count() - 1);
|
|
parent()->emplace_value(position(), alloc, slot(count()));
|
|
value_destroy(count(), alloc);
|
|
parent()->init_child(position() + 1, dest);
|
|
|
|
if (!leaf()) {
|
|
for (int i = 0; i <= dest->count(); ++i) {
|
|
assert(child(count() + i + 1) != nullptr);
|
|
dest->init_child(i, child(count() + i + 1));
|
|
clear_child(count() + i + 1);
|
|
}
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
void btree_node<P>::merge(btree_node *src, allocator_type *alloc) {
|
|
assert(parent() == src->parent());
|
|
assert(position() + 1 == src->position());
|
|
|
|
// Move the delimiting value to the left node.
|
|
value_init(count(), alloc, parent()->slot(position()));
|
|
|
|
// Move the values from the right to the left node.
|
|
src->uninitialized_move_n(src->count(), 0, count() + 1, this, alloc);
|
|
|
|
// Destroy the now-empty entries in the right node.
|
|
src->value_destroy_n(0, src->count(), alloc);
|
|
|
|
if (!leaf()) {
|
|
// Move the child pointers from the right to the left node.
|
|
for (int i = 0; i <= src->count(); ++i) {
|
|
init_child(count() + i + 1, src->child(i));
|
|
src->clear_child(i);
|
|
}
|
|
}
|
|
|
|
// 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(), alloc);
|
|
}
|
|
|
|
template <typename P>
|
|
void btree_node<P>::swap(btree_node *x, allocator_type *alloc) {
|
|
using std::swap;
|
|
assert(leaf() == x->leaf());
|
|
|
|
// Determine which is the smaller/larger node.
|
|
btree_node *smaller = this, *larger = x;
|
|
if (smaller->count() > larger->count()) {
|
|
swap(smaller, larger);
|
|
}
|
|
|
|
// Swap the values.
|
|
for (slot_type *a = smaller->slot(0), *b = larger->slot(0),
|
|
*end = a + smaller->count();
|
|
a != end; ++a, ++b) {
|
|
params_type::swap(alloc, a, b);
|
|
}
|
|
|
|
// Move values that can't be swapped.
|
|
const size_type to_move = larger->count() - smaller->count();
|
|
larger->uninitialized_move_n(to_move, smaller->count(), smaller->count(),
|
|
smaller, alloc);
|
|
larger->value_destroy_n(smaller->count(), to_move, alloc);
|
|
|
|
if (!leaf()) {
|
|
// Swap the child pointers.
|
|
std::swap_ranges(&smaller->mutable_child(0),
|
|
&smaller->mutable_child(smaller->count() + 1),
|
|
&larger->mutable_child(0));
|
|
// Update swapped children's parent pointers.
|
|
int i = 0;
|
|
for (; i <= smaller->count(); ++i) {
|
|
smaller->child(i)->set_parent(smaller);
|
|
larger->child(i)->set_parent(larger);
|
|
}
|
|
// Move the child pointers that couldn't be swapped.
|
|
for (; i <= larger->count(); ++i) {
|
|
smaller->init_child(i, larger->child(i));
|
|
larger->clear_child(i);
|
|
}
|
|
}
|
|
|
|
// Swap the counts.
|
|
swap(mutable_count(), x->mutable_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());
|
|
btree_iterator 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>::decrement_slow() {
|
|
if (node->leaf()) {
|
|
assert(position <= -1);
|
|
btree_iterator save(*this);
|
|
while (position < 0 && !node->is_root()) {
|
|
assert(node->parent()->child(node->position()) == node);
|
|
position = node->position() - 1;
|
|
node = node->parent();
|
|
}
|
|
if (position < 0) {
|
|
*this = save;
|
|
}
|
|
} else {
|
|
assert(position >= 0);
|
|
node = node->child(position);
|
|
while (!node->leaf()) {
|
|
node = node->child(node->count());
|
|
}
|
|
position = node->count() - 1;
|
|
}
|
|
}
|
|
|
|
////
|
|
// btree methods
|
|
template <typename P>
|
|
template <typename Btree>
|
|
void btree<P>::copy_or_move_values_in_order(Btree *x) {
|
|
static_assert(std::is_same<btree, Btree>::value ||
|
|
std::is_same<const btree, Btree>::value,
|
|
"Btree type must be same or const.");
|
|
assert(empty());
|
|
|
|
// We can avoid key comparisons because we know the order of the
|
|
// values is the same order we'll store them in.
|
|
auto iter = x->begin();
|
|
if (iter == x->end()) return;
|
|
insert_multi(maybe_move_from_iterator(iter));
|
|
++iter;
|
|
for (; iter != x->end(); ++iter) {
|
|
// If the btree is not empty, we can just insert the new value at the end
|
|
// of the tree.
|
|
internal_emplace(end(), maybe_move_from_iterator(iter));
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
constexpr bool btree<P>::static_assert_validation() {
|
|
static_assert(std::is_nothrow_copy_constructible<key_compare>::value,
|
|
"Key comparison must be nothrow copy constructible");
|
|
static_assert(std::is_nothrow_copy_constructible<allocator_type>::value,
|
|
"Allocator must be nothrow copy constructible");
|
|
static_assert(type_traits_internal::is_trivially_copyable<iterator>::value,
|
|
"iterator not trivially copyable.");
|
|
|
|
// Note: We assert that kTargetValues, which is computed from
|
|
// Params::kTargetNodeSize, must fit the node_type::field_type.
|
|
static_assert(
|
|
kNodeValues < (1 << (8 * sizeof(typename node_type::field_type))),
|
|
"target node size too large");
|
|
|
|
// Verify that key_compare returns an absl::{weak,strong}_ordering or bool.
|
|
using compare_result_type =
|
|
absl::result_of_t<key_compare(key_type, key_type)>;
|
|
static_assert(
|
|
std::is_same<compare_result_type, bool>::value ||
|
|
std::is_convertible<compare_result_type, absl::weak_ordering>::value,
|
|
"key comparison function must return absl::{weak,strong}_ordering or "
|
|
"bool.");
|
|
|
|
// Test the assumption made in setting kNodeValueSpace.
|
|
static_assert(node_type::MinimumOverhead() >= sizeof(void *) + 4,
|
|
"node space assumption incorrect");
|
|
|
|
return true;
|
|
}
|
|
|
|
template <typename P>
|
|
btree<P>::btree(const key_compare &comp, const allocator_type &alloc)
|
|
: root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {}
|
|
|
|
template <typename P>
|
|
btree<P>::btree(const btree &x) : btree(x.key_comp(), x.allocator()) {
|
|
copy_or_move_values_in_order(&x);
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename... Args>
|
|
auto btree<P>::insert_unique(const key_type &key, Args &&... args)
|
|
-> std::pair<iterator, bool> {
|
|
if (empty()) {
|
|
mutable_root() = rightmost_ = new_leaf_root_node(1);
|
|
}
|
|
|
|
auto res = internal_locate(key);
|
|
iterator &iter = res.value;
|
|
|
|
if (res.HasMatch()) {
|
|
if (res.IsEq()) {
|
|
// The key already exists in the tree, do nothing.
|
|
return {iter, false};
|
|
}
|
|
} else {
|
|
iterator last = internal_last(iter);
|
|
if (last.node && !compare_keys(key, last.key())) {
|
|
// The key already exists in the tree, do nothing.
|
|
return {last, false};
|
|
}
|
|
}
|
|
return {internal_emplace(iter, std::forward<Args>(args)...), true};
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename... Args>
|
|
inline auto btree<P>::insert_hint_unique(iterator position, const key_type &key,
|
|
Args &&... args)
|
|
-> std::pair<iterator, bool> {
|
|
if (!empty()) {
|
|
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_emplace(position, std::forward<Args>(args)...), true};
|
|
}
|
|
} else if (compare_keys(position.key(), key)) {
|
|
++position;
|
|
if (position == end() || compare_keys(key, position.key())) {
|
|
// {original `position`}.key() < key < {current `position`}.key()
|
|
return {internal_emplace(position, std::forward<Args>(args)...), true};
|
|
}
|
|
} else {
|
|
// position.key() == key
|
|
return {position, false};
|
|
}
|
|
}
|
|
return insert_unique(key, std::forward<Args>(args)...);
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename InputIterator>
|
|
void btree<P>::insert_iterator_unique(InputIterator b, InputIterator e) {
|
|
for (; b != e; ++b) {
|
|
insert_hint_unique(end(), params_type::key(*b), *b);
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename ValueType>
|
|
auto btree<P>::insert_multi(const key_type &key, ValueType &&v) -> iterator {
|
|
if (empty()) {
|
|
mutable_root() = rightmost_ = new_leaf_root_node(1);
|
|
}
|
|
|
|
iterator iter = internal_upper_bound(key);
|
|
if (iter.node == nullptr) {
|
|
iter = end();
|
|
}
|
|
return internal_emplace(iter, std::forward<ValueType>(v));
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename ValueType>
|
|
auto btree<P>::insert_hint_multi(iterator position, ValueType &&v) -> iterator {
|
|
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_emplace(position, std::forward<ValueType>(v));
|
|
}
|
|
} else {
|
|
iterator next = position;
|
|
++next;
|
|
if (next == end() || !compare_keys(next.key(), key)) {
|
|
// position.key() < key <= next.key()
|
|
return internal_emplace(next, std::forward<ValueType>(v));
|
|
}
|
|
}
|
|
}
|
|
return insert_multi(std::forward<ValueType>(v));
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename InputIterator>
|
|
void btree<P>::insert_iterator_multi(InputIterator b, InputIterator e) {
|
|
for (; b != e; ++b) {
|
|
insert_hint_multi(end(), *b);
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
auto btree<P>::operator=(const btree &x) -> btree & {
|
|
if (this != &x) {
|
|
clear();
|
|
|
|
*mutable_key_comp() = x.key_comp();
|
|
if (absl::allocator_traits<
|
|
allocator_type>::propagate_on_container_copy_assignment::value) {
|
|
*mutable_allocator() = x.allocator();
|
|
}
|
|
|
|
copy_or_move_values_in_order(&x);
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
template <typename P>
|
|
auto btree<P>::operator=(btree &&x) noexcept -> btree & {
|
|
if (this != &x) {
|
|
clear();
|
|
|
|
using std::swap;
|
|
if (absl::allocator_traits<
|
|
allocator_type>::propagate_on_container_copy_assignment::value) {
|
|
// Note: `root_` also contains the allocator and the key comparator.
|
|
swap(root_, x.root_);
|
|
swap(rightmost_, x.rightmost_);
|
|
swap(size_, x.size_);
|
|
} else {
|
|
if (allocator() == x.allocator()) {
|
|
swap(mutable_root(), x.mutable_root());
|
|
swap(*mutable_key_comp(), *x.mutable_key_comp());
|
|
swap(rightmost_, x.rightmost_);
|
|
swap(size_, x.size_);
|
|
} else {
|
|
// We aren't allowed to propagate the allocator and the allocator is
|
|
// different so we can't take over its memory. We must move each element
|
|
// individually. We need both `x` and `this` to have `x`s key comparator
|
|
// while moving the values so we can't swap the key comparators.
|
|
*mutable_key_comp() = x.key_comp();
|
|
copy_or_move_values_in_order(&x);
|
|
}
|
|
}
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
template <typename P>
|
|
auto btree<P>::erase(iterator iter) -> iterator {
|
|
bool internal_delete = false;
|
|
if (!iter.node->leaf()) {
|
|
// Deletion of a value on an internal node. First, move the largest value
|
|
// from our left child here, then delete that position (in remove_value()
|
|
// below). We can get to the largest value from our left child by
|
|
// decrementing iter.
|
|
iterator internal_iter(iter);
|
|
--iter;
|
|
assert(iter.node->leaf());
|
|
params_type::move(mutable_allocator(), iter.node->slot(iter.position),
|
|
internal_iter.node->slot(internal_iter.position));
|
|
internal_delete = true;
|
|
}
|
|
|
|
// Delete the key from the leaf.
|
|
iter.node->remove_value(iter.position, mutable_allocator());
|
|
--size_;
|
|
|
|
// 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.
|
|
|
|
iterator res = rebalance_after_delete(iter);
|
|
|
|
// If we erased from an internal node, advance the iterator.
|
|
if (internal_delete) {
|
|
++res;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
template <typename P>
|
|
auto btree<P>::rebalance_after_delete(iterator iter) -> iterator {
|
|
// Merge/rebalance as we walk back up the tree.
|
|
iterator res(iter);
|
|
bool first_iteration = true;
|
|
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);
|
|
// On the first iteration, we should update `res` with `iter` because `res`
|
|
// may have been invalidated.
|
|
if (first_iteration) {
|
|
res = iter;
|
|
first_iteration = false;
|
|
}
|
|
if (!merged) {
|
|
break;
|
|
}
|
|
iter.position = iter.node->position();
|
|
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;
|
|
}
|
|
|
|
return res;
|
|
}
|
|
|
|
template <typename P>
|
|
auto btree<P>::erase(iterator begin, iterator end)
|
|
-> std::pair<size_type, iterator> {
|
|
difference_type count = std::distance(begin, end);
|
|
assert(count >= 0);
|
|
|
|
if (count == 0) {
|
|
return {0, begin};
|
|
}
|
|
|
|
if (count == size_) {
|
|
clear();
|
|
return {count, this->end()};
|
|
}
|
|
|
|
if (begin.node == end.node) {
|
|
erase_same_node(begin, end);
|
|
size_ -= count;
|
|
return {count, rebalance_after_delete(begin)};
|
|
}
|
|
|
|
const size_type target_size = size_ - count;
|
|
while (size_ > target_size) {
|
|
if (begin.node->leaf()) {
|
|
const size_type remaining_to_erase = size_ - target_size;
|
|
const size_type remaining_in_node = begin.node->count() - begin.position;
|
|
begin = erase_from_leaf_node(
|
|
begin, (std::min)(remaining_to_erase, remaining_in_node));
|
|
} else {
|
|
begin = erase(begin);
|
|
}
|
|
}
|
|
return {count, begin};
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::erase_same_node(iterator begin, iterator end) {
|
|
assert(begin.node == end.node);
|
|
assert(end.position > begin.position);
|
|
|
|
node_type *node = begin.node;
|
|
size_type to_erase = end.position - begin.position;
|
|
if (!node->leaf()) {
|
|
// Delete all children between begin and end.
|
|
for (size_type i = 0; i < to_erase; ++i) {
|
|
internal_clear(node->child(begin.position + i + 1));
|
|
}
|
|
// Rotate children after end into new positions.
|
|
for (size_type i = begin.position + to_erase + 1; i <= node->count(); ++i) {
|
|
node->set_child(i - to_erase, node->child(i));
|
|
node->clear_child(i);
|
|
}
|
|
}
|
|
node->remove_values_ignore_children(begin.position, to_erase,
|
|
mutable_allocator());
|
|
|
|
// Do not need to update rightmost_, because
|
|
// * either end == this->end(), and therefore node == rightmost_, and still
|
|
// exists
|
|
// * or end != this->end(), and therefore rightmost_ hasn't been erased, since
|
|
// it wasn't covered in [begin, end)
|
|
}
|
|
|
|
template <typename P>
|
|
auto btree<P>::erase_from_leaf_node(iterator begin, size_type to_erase)
|
|
-> iterator {
|
|
node_type *node = begin.node;
|
|
assert(node->leaf());
|
|
assert(node->count() > begin.position);
|
|
assert(begin.position + to_erase <= node->count());
|
|
|
|
node->remove_values_ignore_children(begin.position, to_erase,
|
|
mutable_allocator());
|
|
|
|
size_ -= to_erase;
|
|
|
|
return rebalance_after_delete(begin);
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
auto btree<P>::erase_unique(const K &key) -> size_type {
|
|
const iterator iter = internal_find(key);
|
|
if (iter.node == nullptr) {
|
|
// The key doesn't exist in the tree, return nothing done.
|
|
return 0;
|
|
}
|
|
erase(iter);
|
|
return 1;
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
auto btree<P>::erase_multi(const K &key) -> size_type {
|
|
const iterator begin = internal_lower_bound(key);
|
|
if (begin.node == nullptr) {
|
|
// The key doesn't exist in the tree, return nothing done.
|
|
return 0;
|
|
}
|
|
// Delete all of the keys between begin and upper_bound(key).
|
|
const iterator end = internal_end(internal_upper_bound(key));
|
|
return erase(begin, end).first;
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::clear() {
|
|
if (!empty()) {
|
|
internal_clear(root());
|
|
}
|
|
mutable_root() = EmptyNode();
|
|
rightmost_ = EmptyNode();
|
|
size_ = 0;
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::swap(btree &x) {
|
|
using std::swap;
|
|
if (absl::allocator_traits<
|
|
allocator_type>::propagate_on_container_swap::value) {
|
|
// Note: `root_` also contains the allocator and the key comparator.
|
|
swap(root_, x.root_);
|
|
} else {
|
|
// It's undefined behavior if the allocators are unequal here.
|
|
assert(allocator() == x.allocator());
|
|
swap(mutable_root(), x.mutable_root());
|
|
swap(*mutable_key_comp(), *x.mutable_key_comp());
|
|
}
|
|
swap(rightmost_, x.rightmost_);
|
|
swap(size_, x.size_);
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::verify() const {
|
|
assert(root() != nullptr);
|
|
assert(leftmost() != nullptr);
|
|
assert(rightmost_ != nullptr);
|
|
assert(empty() || size() == internal_verify(root(), nullptr, nullptr));
|
|
assert(leftmost() == (++const_iterator(root(), -1)).node);
|
|
assert(rightmost_ == (--const_iterator(root(), root()->count())).node);
|
|
assert(leftmost()->leaf());
|
|
assert(rightmost_->leaf());
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::rebalance_or_split(iterator *iter) {
|
|
node_type *&node = iter->node;
|
|
int &insert_position = iter->position;
|
|
assert(node->count() == node->max_count());
|
|
assert(kNodeValues == 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);
|
|
assert(left->max_count() == kNodeValues);
|
|
if (left->count() < kNodeValues) {
|
|
// 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 = (kNodeValues - left->count()) /
|
|
(1 + (insert_position < kNodeValues));
|
|
to_move = (std::max)(1, to_move);
|
|
|
|
if (((insert_position - to_move) >= 0) ||
|
|
((left->count() + to_move) < kNodeValues)) {
|
|
left->rebalance_right_to_left(to_move, node, mutable_allocator());
|
|
|
|
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);
|
|
assert(right->max_count() == kNodeValues);
|
|
if (right->count() < kNodeValues) {
|
|
// We bias rebalancing based on the position being inserted. If we're
|
|
// inserting at the beginning of the left node then we bias rebalancing
|
|
// to fill up the right node.
|
|
int to_move =
|
|
(kNodeValues - right->count()) / (1 + (insert_position > 0));
|
|
to_move = (std::max)(1, to_move);
|
|
|
|
if ((insert_position <= (node->count() - to_move)) ||
|
|
((right->count() + to_move) < kNodeValues)) {
|
|
node->rebalance_left_to_right(to_move, right, mutable_allocator());
|
|
|
|
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.
|
|
assert(parent->max_count() == kNodeValues);
|
|
if (parent->count() == kNodeValues) {
|
|
iterator parent_iter(node->parent(), node->position());
|
|
rebalance_or_split(&parent_iter);
|
|
}
|
|
} else {
|
|
// Rebalancing not possible because this is the root node.
|
|
// Create a new root node and set the current root node as the child of the
|
|
// new root.
|
|
parent = new_internal_node(parent);
|
|
parent->init_child(0, root());
|
|
mutable_root() = parent;
|
|
// If the former root was a leaf node, then it's now the rightmost node.
|
|
assert(!parent->child(0)->leaf() || parent->child(0) == rightmost_);
|
|
}
|
|
|
|
// Split the node.
|
|
node_type *split_node;
|
|
if (node->leaf()) {
|
|
split_node = new_leaf_node(parent);
|
|
node->split(insert_position, split_node, mutable_allocator());
|
|
if (rightmost_ == node) rightmost_ = split_node;
|
|
} else {
|
|
split_node = new_internal_node(parent);
|
|
node->split(insert_position, split_node, mutable_allocator());
|
|
}
|
|
|
|
if (insert_position > node->count()) {
|
|
insert_position = insert_position - node->count() - 1;
|
|
node = split_node;
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::merge_nodes(node_type *left, node_type *right) {
|
|
left->merge(right, mutable_allocator());
|
|
if (right->leaf()) {
|
|
if (rightmost_ == right) rightmost_ = left;
|
|
delete_leaf_node(right);
|
|
} else {
|
|
delete_internal_node(right);
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
bool btree<P>::try_merge_or_rebalance(iterator *iter) {
|
|
node_type *parent = iter->node->parent();
|
|
if (iter->node->position() > 0) {
|
|
// Try merging with our left sibling.
|
|
node_type *left = parent->child(iter->node->position() - 1);
|
|
assert(left->max_count() == kNodeValues);
|
|
if ((1 + left->count() + iter->node->count()) <= kNodeValues) {
|
|
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);
|
|
assert(right->max_count() == kNodeValues);
|
|
if ((1 + iter->node->count() + right->count()) <= kNodeValues) {
|
|
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(to_move, right, mutable_allocator());
|
|
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(to_move, iter->node, mutable_allocator());
|
|
iter->position += to_move;
|
|
return false;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::try_shrink() {
|
|
if (root()->count() > 0) {
|
|
return;
|
|
}
|
|
// Deleted the last item on the root node, shrink the height of the tree.
|
|
if (root()->leaf()) {
|
|
assert(size() == 0);
|
|
delete_leaf_node(root());
|
|
mutable_root() = EmptyNode();
|
|
rightmost_ = EmptyNode();
|
|
} else {
|
|
node_type *child = root()->child(0);
|
|
child->make_root();
|
|
delete_internal_node(root());
|
|
mutable_root() = child;
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename IterType>
|
|
inline IterType btree<P>::internal_last(IterType iter) {
|
|
assert(iter.node != nullptr);
|
|
while (iter.position == iter.node->count()) {
|
|
iter.position = iter.node->position();
|
|
iter.node = iter.node->parent();
|
|
if (iter.node->leaf()) {
|
|
iter.node = nullptr;
|
|
break;
|
|
}
|
|
}
|
|
return iter;
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename... Args>
|
|
inline auto btree<P>::internal_emplace(iterator iter, Args &&... args)
|
|
-> iterator {
|
|
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;
|
|
}
|
|
const int max_count = iter.node->max_count();
|
|
if (iter.node->count() == max_count) {
|
|
// Make room in the leaf for the new item.
|
|
if (max_count < kNodeValues) {
|
|
// Insertion into the root where the root is smaller than 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 * max_count));
|
|
iter.node->swap(root(), mutable_allocator());
|
|
delete_leaf_node(root());
|
|
mutable_root() = iter.node;
|
|
rightmost_ = iter.node;
|
|
} else {
|
|
rebalance_or_split(&iter);
|
|
}
|
|
}
|
|
iter.node->emplace_value(iter.position, mutable_allocator(),
|
|
std::forward<Args>(args)...);
|
|
++size_;
|
|
return iter;
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
inline auto btree<P>::internal_locate(const K &key) const
|
|
-> SearchResult<iterator, is_key_compare_to::value> {
|
|
return internal_locate_impl(key, is_key_compare_to());
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
inline auto btree<P>::internal_locate_impl(
|
|
const K &key, std::false_type /* IsCompareTo */) const
|
|
-> SearchResult<iterator, false> {
|
|
iterator iter(const_cast<node_type *>(root()), 0);
|
|
for (;;) {
|
|
iter.position = iter.node->lower_bound(key, key_comp()).value;
|
|
// NOTE: we don't need to walk all the way down the tree if the keys are
|
|
// equal, but determining equality would require doing an extra comparison
|
|
// on each node on the way down, and we will need to go all the way to the
|
|
// leaf node in the expected case.
|
|
if (iter.node->leaf()) {
|
|
break;
|
|
}
|
|
iter.node = iter.node->child(iter.position);
|
|
}
|
|
return {iter};
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
inline auto btree<P>::internal_locate_impl(
|
|
const K &key, std::true_type /* IsCompareTo */) const
|
|
-> SearchResult<iterator, true> {
|
|
iterator iter(const_cast<node_type *>(root()), 0);
|
|
for (;;) {
|
|
SearchResult<int, true> res = iter.node->lower_bound(key, key_comp());
|
|
iter.position = res.value;
|
|
if (res.match == MatchKind::kEq) {
|
|
return {iter, MatchKind::kEq};
|
|
}
|
|
if (iter.node->leaf()) {
|
|
break;
|
|
}
|
|
iter.node = iter.node->child(iter.position);
|
|
}
|
|
return {iter, MatchKind::kNe};
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
auto btree<P>::internal_lower_bound(const K &key) const -> iterator {
|
|
iterator iter(const_cast<node_type *>(root()), 0);
|
|
for (;;) {
|
|
iter.position = iter.node->lower_bound(key, key_comp()).value;
|
|
if (iter.node->leaf()) {
|
|
break;
|
|
}
|
|
iter.node = iter.node->child(iter.position);
|
|
}
|
|
return internal_last(iter);
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
auto btree<P>::internal_upper_bound(const K &key) const -> iterator {
|
|
iterator iter(const_cast<node_type *>(root()), 0);
|
|
for (;;) {
|
|
iter.position = iter.node->upper_bound(key, key_comp());
|
|
if (iter.node->leaf()) {
|
|
break;
|
|
}
|
|
iter.node = iter.node->child(iter.position);
|
|
}
|
|
return internal_last(iter);
|
|
}
|
|
|
|
template <typename P>
|
|
template <typename K>
|
|
auto btree<P>::internal_find(const K &key) const -> iterator {
|
|
auto res = internal_locate(key);
|
|
if (res.HasMatch()) {
|
|
if (res.IsEq()) {
|
|
return res.value;
|
|
}
|
|
} else {
|
|
const iterator iter = internal_last(res.value);
|
|
if (iter.node != nullptr && !compare_keys(key, iter.key())) {
|
|
return iter;
|
|
}
|
|
}
|
|
return {nullptr, 0};
|
|
}
|
|
|
|
template <typename P>
|
|
void btree<P>::internal_clear(node_type *node) {
|
|
if (!node->leaf()) {
|
|
for (int i = 0; i <= node->count(); ++i) {
|
|
internal_clear(node->child(i));
|
|
}
|
|
delete_internal_node(node);
|
|
} else {
|
|
delete_leaf_node(node);
|
|
}
|
|
}
|
|
|
|
template <typename P>
|
|
int btree<P>::internal_verify(
|
|
const node_type *node, const key_type *lo, const key_type *hi) const {
|
|
assert(node->count() > 0);
|
|
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) != nullptr);
|
|
assert(node->child(i)->parent() == node);
|
|
assert(node->child(i)->position() == i);
|
|
count += internal_verify(
|
|
node->child(i),
|
|
(i == 0) ? lo : &node->key(i - 1),
|
|
(i == node->count()) ? hi : &node->key(i));
|
|
}
|
|
}
|
|
return count;
|
|
}
|
|
|
|
} // namespace container_internal
|
|
ABSL_NAMESPACE_END
|
|
} // namespace absl
|
|
|
|
#endif // ABSL_CONTAINER_INTERNAL_BTREE_H_
|