2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 * This header defines two classes that very nearly model
19 * AssociativeContainer (but not quite). These implement set-like and
20 * map-like behavior on top of a sorted vector, instead of using
21 * rb-trees like std::set and std::map.
23 * This is potentially useful in cases where the number of elements in
24 * the set or map is small, or when you want to avoid using more
25 * memory than necessary and insertions/deletions are much more rare
26 * than lookups (these classes have O(N) insertions/deletions).
28 * In the interest of using these in conditions where the goal is to
29 * minimize memory usage, they support a GrowthPolicy parameter, which
30 * is a class defining a single function called increase_capacity,
31 * which will be called whenever we are about to insert something: you
32 * can then decide to call reserve() based on the current capacity()
33 * and size() of the passed in vector-esque Container type. An
34 * example growth policy that grows one element at a time:
36 * struct OneAtATimePolicy {
37 * template<class Container>
38 * void increase_capacity(Container& c) {
39 * if (c.size() == c.capacity()) {
40 * c.reserve(c.size() + 1);
45 * typedef sorted_vector_set<int,
47 * std::allocator<int>,
51 * Important differences from std::set and std::map:
52 * - insert() and erase() invalidate iterators and references
53 * - insert() and erase() are O(N)
54 * - our iterators model RandomAccessIterator
55 * - sorted_vector_map::value_type is pair<K,V>, not pair<const K,V>.
56 * (This is basically because we want to store the value_type in
57 * std::vector<>, which requires it to be Assignable.)
63 #include <initializer_list>
66 #include <type_traits>
70 #include <boost/operators.hpp>
71 #include <folly/portability/BitsFunctexcept.h>
75 //////////////////////////////////////////////////////////////////////
79 // This wrapper goes around a GrowthPolicy and provides iterator
80 // preservation semantics, but only if the growth policy is not the
81 // default (i.e. nothing).
82 template<class Policy>
83 struct growth_policy_wrapper : private Policy {
84 template<class Container, class Iterator>
85 Iterator increase_capacity(Container& c, Iterator desired_insertion)
87 typedef typename Container::difference_type diff_t;
88 diff_t d = desired_insertion - c.begin();
89 Policy::increase_capacity(c);
94 struct growth_policy_wrapper<void> {
95 template<class Container, class Iterator>
96 Iterator increase_capacity(Container&, Iterator it) {
102 * This helper returns the distance between two iterators if it is
103 * possible to figure it out without messing up the range
104 * (i.e. unless they are InputIterators). Otherwise this returns
107 template<class Iterator>
108 int distance_if_multipass(Iterator first, Iterator last) {
109 typedef typename std::iterator_traits<Iterator>::iterator_category categ;
110 if (std::is_same<categ,std::input_iterator_tag>::value)
112 return std::distance(first, last);
115 template<class OurContainer, class Vector, class GrowthPolicy>
116 typename OurContainer::iterator
117 insert_with_hint(OurContainer& sorted,
119 typename OurContainer::iterator hint,
120 typename OurContainer::value_type&& value,
123 const typename OurContainer::value_compare& cmp(sorted.value_comp());
124 if (hint == cont.end() || cmp(value, *hint)) {
125 if (hint == cont.begin()) {
126 po.increase_capacity(cont, cont.begin());
127 return cont.insert(cont.begin(), std::move(value));
129 if (cmp(*(hint - 1), value)) {
130 hint = po.increase_capacity(cont, hint);
131 return cont.insert(hint, std::move(value));
133 return sorted.insert(std::move(value)).first;
136 if (cmp(*hint, value)) {
137 if (hint + 1 == cont.end() || cmp(value, *(hint + 1))) {
138 typename OurContainer::iterator it =
139 po.increase_capacity(cont, hint + 1);
140 return cont.insert(it, std::move(value));
144 // Value and *hint did not compare, so they are equal keys.
148 template <class OurContainer, class Vector, class InputIterator>
150 OurContainer& sorted,
153 InputIterator last) {
154 // prevent deref of middle where middle == cont.end()
159 auto const& cmp(sorted.value_comp());
161 int const d = distance_if_multipass(first, last);
163 cont.reserve(cont.size() + d);
165 auto const prev_size = cont.size();
167 std::copy(first, last, std::back_inserter(cont));
168 auto const middle = cont.begin() + prev_size;
169 if (!std::is_sorted(middle, cont.end(), cmp)) {
170 std::sort(middle, cont.end(), cmp);
172 if (middle != cont.begin() && cmp(*middle, *(middle - 1))) {
173 std::inplace_merge(cont.begin(), middle, cont.end(), cmp);
174 auto last = std::unique(
177 [&](typename OurContainer::value_type const& a,
178 typename OurContainer::value_type const& b) {
179 return !cmp(a, b) && !cmp(b, a);
181 cont.erase(last, cont.end());
186 //////////////////////////////////////////////////////////////////////
189 * A sorted_vector_set is a container similar to std::set<>, but
190 * implemented as as a sorted array with std::vector<>.
192 * @param class T Data type to store
193 * @param class Compare Comparison function that imposes a
194 * strict weak ordering over instances of T
195 * @param class Allocator allocation policy
196 * @param class GrowthPolicy policy object to control growth
198 * @author Aditya Agarwal <aditya@fb.com>
199 * @author Akhil Wable <akhil@fb.com>
200 * @author Jordan DeLong <delong.j@fb.com>
203 class Compare = std::less<T>,
204 class Allocator = std::allocator<T>,
205 class GrowthPolicy = void>
206 class sorted_vector_set
207 : boost::totally_ordered1<
208 sorted_vector_set<T,Compare,Allocator,GrowthPolicy>
209 , detail::growth_policy_wrapper<GrowthPolicy> >
211 typedef std::vector<T,Allocator> ContainerT;
213 detail::growth_policy_wrapper<GrowthPolicy>&
214 get_growth_policy() { return *this; }
217 typedef T value_type;
219 typedef Compare key_compare;
220 typedef Compare value_compare;
222 typedef typename ContainerT::pointer pointer;
223 typedef typename ContainerT::reference reference;
224 typedef typename ContainerT::const_reference const_reference;
226 * XXX: Our normal iterator ought to also be a constant iterator
227 * (cf. Defect Report 103 for std::set), but this is a bit more of a
230 typedef typename ContainerT::iterator iterator;
231 typedef typename ContainerT::const_iterator const_iterator;
232 typedef typename ContainerT::difference_type difference_type;
233 typedef typename ContainerT::size_type size_type;
234 typedef typename ContainerT::reverse_iterator reverse_iterator;
235 typedef typename ContainerT::const_reverse_iterator const_reverse_iterator;
237 explicit sorted_vector_set(const Compare& comp = Compare(),
238 const Allocator& alloc = Allocator())
242 template<class InputIterator>
243 explicit sorted_vector_set(
246 const Compare& comp = Compare(),
247 const Allocator& alloc = Allocator())
250 // This is linear if [first, last) is already sorted (and if we
251 // can figure out the distance between the two iterators).
255 /* implicit */ sorted_vector_set(
256 std::initializer_list<value_type> list,
257 const Compare& comp = Compare(),
258 const Allocator& alloc = Allocator())
261 insert(list.begin(), list.end());
264 // Construct a sorted_vector_set by stealing the storage of a prefilled
265 // container. The container need not be sorted already. This supports
266 // bulk construction of sorted_vector_set with zero allocations, not counting
267 // those performed by the caller. (The iterator range constructor performs at
268 // least one allocation).
270 // Note that `sorted_vector_set(const ContainerT& container)` is not provided,
271 // since the purpose of this constructor is to avoid an unnecessary copy.
272 explicit sorted_vector_set(
273 ContainerT&& container,
274 const Compare& comp = Compare())
275 : m_(comp, container.get_allocator()) {
276 std::sort(container.begin(), container.end(), value_comp());
277 m_.cont_.swap(container);
280 key_compare key_comp() const { return m_; }
281 value_compare value_comp() const { return m_; }
283 iterator begin() { return m_.cont_.begin(); }
284 iterator end() { return m_.cont_.end(); }
285 const_iterator cbegin() const { return m_.cont_.cbegin(); }
286 const_iterator begin() const { return m_.cont_.begin(); }
287 const_iterator cend() const { return m_.cont_.cend(); }
288 const_iterator end() const { return m_.cont_.end(); }
289 reverse_iterator rbegin() { return m_.cont_.rbegin(); }
290 reverse_iterator rend() { return m_.cont_.rend(); }
291 const_reverse_iterator rbegin() const { return m_.cont_.rbegin(); }
292 const_reverse_iterator rend() const { return m_.cont_.rend(); }
294 void clear() { return m_.cont_.clear(); }
295 size_type size() const { return m_.cont_.size(); }
296 size_type max_size() const { return m_.cont_.max_size(); }
297 bool empty() const { return m_.cont_.empty(); }
298 void reserve(size_type s) { return m_.cont_.reserve(s); }
299 void shrink_to_fit() { m_.cont_.shrink_to_fit(); }
300 size_type capacity() const { return m_.cont_.capacity(); }
302 std::pair<iterator,bool> insert(const value_type& value) {
303 return insert(std::move(value_type(value)));
306 std::pair<iterator,bool> insert(value_type&& value) {
307 iterator it = lower_bound(value);
308 if (it == end() || value_comp()(value, *it)) {
309 it = get_growth_policy().increase_capacity(m_.cont_, it);
310 return std::make_pair(m_.cont_.insert(it, std::move(value)), true);
312 return std::make_pair(it, false);
315 iterator insert(iterator hint, const value_type& value) {
316 return insert(hint, std::move(value_type(value)));
319 iterator insert(iterator hint, value_type&& value) {
320 return detail::insert_with_hint(*this, m_.cont_, hint, std::move(value),
321 get_growth_policy());
324 template<class InputIterator>
325 void insert(InputIterator first, InputIterator last) {
326 detail::bulk_insert(*this, m_.cont_, first, last);
329 size_type erase(const key_type& key) {
330 iterator it = find(key);
338 void erase(iterator it) {
342 void erase(iterator first, iterator last) {
343 m_.cont_.erase(first, last);
346 iterator find(const key_type& key) {
347 iterator it = lower_bound(key);
348 if (it == end() || !key_comp()(key, *it))
353 const_iterator find(const key_type& key) const {
354 const_iterator it = lower_bound(key);
355 if (it == end() || !key_comp()(key, *it))
360 size_type count(const key_type& key) const {
361 return find(key) == end() ? 0 : 1;
364 iterator lower_bound(const key_type& key) {
365 return std::lower_bound(begin(), end(), key, key_comp());
368 const_iterator lower_bound(const key_type& key) const {
369 return std::lower_bound(begin(), end(), key, key_comp());
372 iterator upper_bound(const key_type& key) {
373 return std::upper_bound(begin(), end(), key, key_comp());
376 const_iterator upper_bound(const key_type& key) const {
377 return std::upper_bound(begin(), end(), key, key_comp());
380 std::pair<iterator,iterator> equal_range(const key_type& key) {
381 return std::equal_range(begin(), end(), key, key_comp());
384 std::pair<const_iterator,const_iterator>
385 equal_range(const key_type& key) const {
386 return std::equal_range(begin(), end(), key, key_comp());
389 // Nothrow as long as swap() on the Compare type is nothrow.
390 void swap(sorted_vector_set& o) {
391 using std::swap; // Allow ADL for swap(); fall back to std::swap().
395 m_.cont_.swap(o.m_.cont_);
398 bool operator==(const sorted_vector_set& other) const {
399 return other.m_.cont_ == m_.cont_;
402 bool operator<(const sorted_vector_set& other) const {
403 return m_.cont_ < other.m_.cont_;
408 * This structure derives from the comparison object in order to
409 * make use of the empty base class optimization if our comparison
410 * functor is an empty class (usual case).
412 * Wrapping up this member like this is better than deriving from
413 * the Compare object ourselves (there are some perverse edge cases
414 * involving virtual functions).
416 * More info: http://www.cantrip.org/emptyopt.html
418 struct EBO : Compare {
419 explicit EBO(const Compare& c, const Allocator& alloc)
427 // Swap function that can be found using ADL.
428 template<class T, class C, class A, class G>
429 inline void swap(sorted_vector_set<T,C,A,G>& a,
430 sorted_vector_set<T,C,A,G>& b) {
434 //////////////////////////////////////////////////////////////////////
437 * A sorted_vector_map is similar to a sorted_vector_set but stores
438 * <key,value> pairs instead of single elements.
440 * @param class Key Key type
441 * @param class Value Value type
442 * @param class Compare Function that can compare key types and impose
443 * a strict weak ordering over them.
444 * @param class Allocator allocation policy
445 * @param class GrowthPolicy policy object to control growth
447 * @author Aditya Agarwal <aditya@fb.com>
448 * @author Akhil Wable <akhil@fb.com>
449 * @author Jordan DeLong <delong.j@fb.com>
453 class Compare = std::less<Key>,
454 class Allocator = std::allocator<std::pair<Key,Value> >,
455 class GrowthPolicy = void>
456 class sorted_vector_map
457 : boost::totally_ordered1<
458 sorted_vector_map<Key,Value,Compare,Allocator,GrowthPolicy>
459 , detail::growth_policy_wrapper<GrowthPolicy> >
461 typedef std::vector<std::pair<Key,Value>,Allocator> ContainerT;
463 detail::growth_policy_wrapper<GrowthPolicy>&
464 get_growth_policy() { return *this; }
467 typedef Key key_type;
468 typedef Value mapped_type;
469 typedef std::pair<key_type,mapped_type> value_type;
470 typedef Compare key_compare;
472 struct value_compare : private Compare {
473 bool operator()(const value_type& a, const value_type& b) const {
474 return Compare::operator()(a.first, b.first);
478 friend class sorted_vector_map;
479 explicit value_compare(const Compare& c) : Compare(c) {}
482 typedef typename ContainerT::pointer pointer;
483 typedef typename ContainerT::reference reference;
484 typedef typename ContainerT::const_reference const_reference;
485 typedef typename ContainerT::iterator iterator;
486 typedef typename ContainerT::const_iterator const_iterator;
487 typedef typename ContainerT::difference_type difference_type;
488 typedef typename ContainerT::size_type size_type;
489 typedef typename ContainerT::reverse_iterator reverse_iterator;
490 typedef typename ContainerT::const_reverse_iterator const_reverse_iterator;
492 explicit sorted_vector_map(const Compare& comp = Compare(),
493 const Allocator& alloc = Allocator())
494 : m_(value_compare(comp), alloc)
497 template<class InputIterator>
498 explicit sorted_vector_map(
501 const Compare& comp = Compare(),
502 const Allocator& alloc = Allocator())
503 : m_(value_compare(comp), alloc)
508 explicit sorted_vector_map(
509 std::initializer_list<value_type> list,
510 const Compare& comp = Compare(),
511 const Allocator& alloc = Allocator())
512 : m_(value_compare(comp), alloc)
514 insert(list.begin(), list.end());
517 // Construct a sorted_vector_map by stealing the storage of a prefilled
518 // container. The container need not be sorted already. This supports
519 // bulk construction of sorted_vector_map with zero allocations, not counting
520 // those performed by the caller. (The iterator range constructor performs at
521 // least one allocation).
523 // Note that `sorted_vector_map(const ContainerT& container)` is not provided,
524 // since the purpose of this constructor is to avoid an unnecessary copy.
525 explicit sorted_vector_map(
526 ContainerT&& container,
527 const Compare& comp = Compare())
528 : m_(value_compare(comp), container.get_allocator()) {
529 std::sort(container.begin(), container.end(), value_comp());
530 m_.cont_.swap(container);
533 key_compare key_comp() const { return m_; }
534 value_compare value_comp() const { return m_; }
536 iterator begin() { return m_.cont_.begin(); }
537 iterator end() { return m_.cont_.end(); }
538 const_iterator cbegin() const { return m_.cont_.cbegin(); }
539 const_iterator begin() const { return m_.cont_.begin(); }
540 const_iterator cend() const { return m_.cont_.cend(); }
541 const_iterator end() const { return m_.cont_.end(); }
542 reverse_iterator rbegin() { return m_.cont_.rbegin(); }
543 reverse_iterator rend() { return m_.cont_.rend(); }
544 const_reverse_iterator rbegin() const { return m_.cont_.rbegin(); }
545 const_reverse_iterator rend() const { return m_.cont_.rend(); }
547 void clear() { return m_.cont_.clear(); }
548 size_type size() const { return m_.cont_.size(); }
549 size_type max_size() const { return m_.cont_.max_size(); }
550 bool empty() const { return m_.cont_.empty(); }
551 void reserve(size_type s) { return m_.cont_.reserve(s); }
552 void shrink_to_fit() { m_.cont_.shrink_to_fit(); }
553 size_type capacity() const { return m_.cont_.capacity(); }
555 std::pair<iterator,bool> insert(const value_type& value) {
556 return insert(std::move(value_type(value)));
559 std::pair<iterator,bool> insert(value_type&& value) {
560 iterator it = lower_bound(value.first);
561 if (it == end() || value_comp()(value, *it)) {
562 it = get_growth_policy().increase_capacity(m_.cont_, it);
563 return std::make_pair(m_.cont_.insert(it, std::move(value)), true);
565 return std::make_pair(it, false);
568 iterator insert(iterator hint, const value_type& value) {
569 return insert(hint, std::move(value_type(value)));
572 iterator insert(iterator hint, value_type&& value) {
573 return detail::insert_with_hint(*this, m_.cont_, hint, std::move(value),
574 get_growth_policy());
577 template<class InputIterator>
578 void insert(InputIterator first, InputIterator last) {
579 detail::bulk_insert(*this, m_.cont_, first, last);
582 size_type erase(const key_type& key) {
583 iterator it = find(key);
591 void erase(iterator it) {
595 void erase(iterator first, iterator last) {
596 m_.cont_.erase(first, last);
599 iterator find(const key_type& key) {
600 iterator it = lower_bound(key);
601 if (it == end() || !key_comp()(key, it->first))
606 const_iterator find(const key_type& key) const {
607 const_iterator it = lower_bound(key);
608 if (it == end() || !key_comp()(key, it->first))
613 mapped_type& at(const key_type& key) {
614 iterator it = find(key);
618 std::__throw_out_of_range("sorted_vector_map::at");
621 const mapped_type& at(const key_type& key) const {
622 const_iterator it = find(key);
626 std::__throw_out_of_range("sorted_vector_map::at");
629 size_type count(const key_type& key) const {
630 return find(key) == end() ? 0 : 1;
633 iterator lower_bound(const key_type& key) {
635 auto f = [&](const value_type& a, const key_type& b) {
636 return c(a.first, b);
638 return std::lower_bound(begin(), end(), key, f);
641 const_iterator lower_bound(const key_type& key) const {
643 auto f = [&](const value_type& a, const key_type& b) {
644 return c(a.first, b);
646 return std::lower_bound(begin(), end(), key, f);
649 iterator upper_bound(const key_type& key) {
651 auto f = [&](const key_type& a, const value_type& b) {
652 return c(a, b.first);
654 return std::upper_bound(begin(), end(), key, f);
657 const_iterator upper_bound(const key_type& key) const {
659 auto f = [&](const key_type& a, const value_type& b) {
660 return c(a, b.first);
662 return std::upper_bound(begin(), end(), key, f);
665 std::pair<iterator,iterator> equal_range(const key_type& key) {
666 // Note: std::equal_range can't be passed a functor that takes
667 // argument types different from the iterator value_type, so we
669 iterator low = lower_bound(key);
671 auto f = [&](const key_type& a, const value_type& b) {
672 return c(a, b.first);
674 iterator high = std::upper_bound(low, end(), key, f);
675 return std::make_pair(low, high);
678 std::pair<const_iterator,const_iterator>
679 equal_range(const key_type& key) const {
680 return const_cast<sorted_vector_map*>(this)->equal_range(key);
683 // Nothrow as long as swap() on the Compare type is nothrow.
684 void swap(sorted_vector_map& o) {
685 using std::swap; // Allow ADL for swap(); fall back to std::swap().
689 m_.cont_.swap(o.m_.cont_);
692 mapped_type& operator[](const key_type& key) {
693 iterator it = lower_bound(key);
694 if (it == end() || key_comp()(key, it->first)) {
695 return insert(it, value_type(key, mapped_type()))->second;
700 bool operator==(const sorted_vector_map& other) const {
701 return m_.cont_ == other.m_.cont_;
704 bool operator<(const sorted_vector_map& other) const {
705 return m_.cont_ < other.m_.cont_;
709 // This is to get the empty base optimization; see the comment in
710 // sorted_vector_set.
711 struct EBO : value_compare {
712 explicit EBO(const value_compare& c, const Allocator& alloc)
720 // Swap function that can be found using ADL.
721 template<class K, class V, class C, class A, class G>
722 inline void swap(sorted_vector_map<K,V,C,A,G>& a,
723 sorted_vector_map<K,V,C,A,G>& b) {
727 //////////////////////////////////////////////////////////////////////