2 * Copyright 2016 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>
74 //////////////////////////////////////////////////////////////////////
78 // This wrapper goes around a GrowthPolicy and provides iterator
79 // preservation semantics, but only if the growth policy is not the
80 // default (i.e. nothing).
81 template<class Policy>
82 struct growth_policy_wrapper : private Policy {
83 template<class Container, class Iterator>
84 Iterator increase_capacity(Container& c, Iterator desired_insertion)
86 typedef typename Container::difference_type diff_t;
87 diff_t d = desired_insertion - c.begin();
88 Policy::increase_capacity(c);
93 struct growth_policy_wrapper<void> {
94 template<class Container, class Iterator>
95 Iterator increase_capacity(Container&, Iterator it) {
101 * This helper returns the distance between two iterators if it is
102 * possible to figure it out without messing up the range
103 * (i.e. unless they are InputIterators). Otherwise this returns
106 template<class Iterator>
107 int distance_if_multipass(Iterator first, Iterator last) {
108 typedef typename std::iterator_traits<Iterator>::iterator_category categ;
109 if (std::is_same<categ,std::input_iterator_tag>::value)
111 return std::distance(first, last);
114 template<class OurContainer, class Vector, class GrowthPolicy>
115 typename OurContainer::iterator
116 insert_with_hint(OurContainer& sorted,
118 typename OurContainer::iterator hint,
119 typename OurContainer::value_type&& value,
122 const typename OurContainer::value_compare& cmp(sorted.value_comp());
123 if (hint == cont.end() || cmp(value, *hint)) {
124 if (hint == cont.begin()) {
125 po.increase_capacity(cont, cont.begin());
126 return cont.insert(cont.begin(), std::move(value));
128 if (cmp(*(hint - 1), value)) {
129 hint = po.increase_capacity(cont, hint);
130 return cont.insert(hint, std::move(value));
132 return sorted.insert(std::move(value)).first;
135 if (cmp(*hint, value)) {
136 if (hint + 1 == cont.end() || cmp(value, *(hint + 1))) {
137 typename OurContainer::iterator it =
138 po.increase_capacity(cont, hint + 1);
139 return cont.insert(it, std::move(value));
143 // Value and *hint did not compare, so they are equal keys.
149 //////////////////////////////////////////////////////////////////////
152 * A sorted_vector_set is a container similar to std::set<>, but
153 * implemented as as a sorted array with std::vector<>.
155 * @param class T Data type to store
156 * @param class Compare Comparison function that imposes a
157 * strict weak ordering over instances of T
158 * @param class Allocator allocation policy
159 * @param class GrowthPolicy policy object to control growth
161 * @author Aditya Agarwal <aditya@fb.com>
162 * @author Akhil Wable <akhil@fb.com>
163 * @author Jordan DeLong <delong.j@fb.com>
166 class Compare = std::less<T>,
167 class Allocator = std::allocator<T>,
168 class GrowthPolicy = void>
169 class sorted_vector_set
170 : boost::totally_ordered1<
171 sorted_vector_set<T,Compare,Allocator,GrowthPolicy>
172 , detail::growth_policy_wrapper<GrowthPolicy> >
174 typedef std::vector<T,Allocator> ContainerT;
176 detail::growth_policy_wrapper<GrowthPolicy>&
177 get_growth_policy() { return *this; }
180 typedef T value_type;
182 typedef Compare key_compare;
183 typedef Compare value_compare;
185 typedef typename ContainerT::pointer pointer;
186 typedef typename ContainerT::reference reference;
187 typedef typename ContainerT::const_reference const_reference;
189 * XXX: Our normal iterator ought to also be a constant iterator
190 * (cf. Defect Report 103 for std::set), but this is a bit more of a
193 typedef typename ContainerT::iterator iterator;
194 typedef typename ContainerT::const_iterator const_iterator;
195 typedef typename ContainerT::difference_type difference_type;
196 typedef typename ContainerT::size_type size_type;
197 typedef typename ContainerT::reverse_iterator reverse_iterator;
198 typedef typename ContainerT::const_reverse_iterator const_reverse_iterator;
200 explicit sorted_vector_set(const Compare& comp = Compare(),
201 const Allocator& alloc = Allocator())
205 template<class InputIterator>
206 explicit sorted_vector_set(
209 const Compare& comp = Compare(),
210 const Allocator& alloc = Allocator())
213 // This is linear if [first, last) is already sorted (and if we
214 // can figure out the distance between the two iterators).
218 explicit sorted_vector_set(
219 std::initializer_list<value_type> list,
220 const Compare& comp = Compare(),
221 const Allocator& alloc = Allocator())
224 insert(list.begin(), list.end());
227 key_compare key_comp() const { return m_; }
228 value_compare value_comp() const { return m_; }
230 iterator begin() { return m_.cont_.begin(); }
231 iterator end() { return m_.cont_.end(); }
232 const_iterator cbegin() const { return m_.cont_.cbegin(); }
233 const_iterator begin() const { return m_.cont_.begin(); }
234 const_iterator cend() const { return m_.cont_.cend(); }
235 const_iterator end() const { return m_.cont_.end(); }
236 reverse_iterator rbegin() { return m_.cont_.rbegin(); }
237 reverse_iterator rend() { return m_.cont_.rend(); }
238 const_reverse_iterator rbegin() const { return m_.cont_.rbegin(); }
239 const_reverse_iterator rend() const { return m_.cont_.rend(); }
241 void clear() { return m_.cont_.clear(); }
242 size_type size() const { return m_.cont_.size(); }
243 size_type max_size() const { return m_.cont_.max_size(); }
244 bool empty() const { return m_.cont_.empty(); }
245 void reserve(size_type s) { return m_.cont_.reserve(s); }
246 void shrink_to_fit() { m_.cont_.shrink_to_fit(); }
247 size_type capacity() const { return m_.cont_.capacity(); }
249 std::pair<iterator,bool> insert(const value_type& value) {
250 return insert(std::move(value_type(value)));
253 std::pair<iterator,bool> insert(value_type&& value) {
254 iterator it = lower_bound(value);
255 if (it == end() || value_comp()(value, *it)) {
256 it = get_growth_policy().increase_capacity(m_.cont_, it);
257 return std::make_pair(m_.cont_.insert(it, std::move(value)), true);
259 return std::make_pair(it, false);
262 iterator insert(iterator hint, const value_type& value) {
263 return insert(hint, std::move(value_type(value)));
266 iterator insert(iterator hint, value_type&& value) {
267 return detail::insert_with_hint(*this, m_.cont_, hint, std::move(value),
268 get_growth_policy());
271 template<class InputIterator>
272 void insert(InputIterator first, InputIterator last) {
273 int d = detail::distance_if_multipass(first, last);
275 m_.cont_.reserve(m_.cont_.size() + d);
277 for (; first != last; ++first) {
278 insert(end(), *first);
282 size_type erase(const key_type& key) {
283 iterator it = lower_bound(key);
291 void erase(iterator it) {
295 void erase(iterator first, iterator last) {
296 m_.cont_.erase(first, last);
299 iterator find(const key_type& key) {
300 iterator it = lower_bound(key);
301 if (it == end() || !key_comp()(key, *it))
306 const_iterator find(const key_type& key) const {
307 const_iterator it = lower_bound(key);
308 if (it == end() || !key_comp()(key, *it))
313 size_type count(const key_type& key) const {
314 return find(key) == end() ? 0 : 1;
317 iterator lower_bound(const key_type& key) {
318 return std::lower_bound(begin(), end(), key, key_comp());
321 const_iterator lower_bound(const key_type& key) const {
322 return std::lower_bound(begin(), end(), key, key_comp());
325 iterator upper_bound(const key_type& key) {
326 return std::upper_bound(begin(), end(), key, key_comp());
329 const_iterator upper_bound(const key_type& key) const {
330 return std::upper_bound(begin(), end(), key, key_comp());
333 std::pair<iterator,iterator> equal_range(const key_type& key) {
334 return std::equal_range(begin(), end(), key, key_comp());
337 std::pair<const_iterator,const_iterator>
338 equal_range(const key_type& key) const {
339 return std::equal_range(begin(), end(), key, key_comp());
342 // Nothrow as long as swap() on the Compare type is nothrow.
343 void swap(sorted_vector_set& o) {
344 using std::swap; // Allow ADL for swap(); fall back to std::swap().
348 m_.cont_.swap(o.m_.cont_);
351 bool operator==(const sorted_vector_set& other) const {
352 return other.m_.cont_ == m_.cont_;
355 bool operator<(const sorted_vector_set& other) const {
356 return m_.cont_ < other.m_.cont_;
361 * This structure derives from the comparison object in order to
362 * make use of the empty base class optimization if our comparison
363 * functor is an empty class (usual case).
365 * Wrapping up this member like this is better than deriving from
366 * the Compare object ourselves (there are some perverse edge cases
367 * involving virtual functions).
369 * More info: http://www.cantrip.org/emptyopt.html
371 struct EBO : Compare {
372 explicit EBO(const Compare& c, const Allocator& alloc)
380 // Swap function that can be found using ADL.
381 template<class T, class C, class A, class G>
382 inline void swap(sorted_vector_set<T,C,A,G>& a,
383 sorted_vector_set<T,C,A,G>& b) {
387 //////////////////////////////////////////////////////////////////////
390 * A sorted_vector_map is similar to a sorted_vector_set but stores
391 * <key,value> pairs instead of single elements.
393 * @param class Key Key type
394 * @param class Value Value type
395 * @param class Compare Function that can compare key types and impose
396 * a strict weak ordering over them.
397 * @param class Allocator allocation policy
398 * @param class GrowthPolicy policy object to control growth
400 * @author Aditya Agarwal <aditya@fb.com>
401 * @author Akhil Wable <akhil@fb.com>
402 * @author Jordan DeLong <delong.j@fb.com>
406 class Compare = std::less<Key>,
407 class Allocator = std::allocator<std::pair<Key,Value> >,
408 class GrowthPolicy = void>
409 class sorted_vector_map
410 : boost::totally_ordered1<
411 sorted_vector_map<Key,Value,Compare,Allocator,GrowthPolicy>
412 , detail::growth_policy_wrapper<GrowthPolicy> >
414 typedef std::vector<std::pair<Key,Value>,Allocator> ContainerT;
416 detail::growth_policy_wrapper<GrowthPolicy>&
417 get_growth_policy() { return *this; }
420 typedef Key key_type;
421 typedef Value mapped_type;
422 typedef std::pair<key_type,mapped_type> value_type;
423 typedef Compare key_compare;
425 struct value_compare : private Compare {
426 bool operator()(const value_type& a, const value_type& b) const {
427 return Compare::operator()(a.first, b.first);
431 friend class sorted_vector_map;
432 explicit value_compare(const Compare& c) : Compare(c) {}
435 typedef typename ContainerT::pointer pointer;
436 typedef typename ContainerT::reference reference;
437 typedef typename ContainerT::const_reference const_reference;
438 typedef typename ContainerT::iterator iterator;
439 typedef typename ContainerT::const_iterator const_iterator;
440 typedef typename ContainerT::difference_type difference_type;
441 typedef typename ContainerT::size_type size_type;
442 typedef typename ContainerT::reverse_iterator reverse_iterator;
443 typedef typename ContainerT::const_reverse_iterator const_reverse_iterator;
445 explicit sorted_vector_map(const Compare& comp = Compare(),
446 const Allocator& alloc = Allocator())
447 : m_(value_compare(comp), alloc)
450 template<class InputIterator>
451 explicit sorted_vector_map(
454 const Compare& comp = Compare(),
455 const Allocator& alloc = Allocator())
456 : m_(value_compare(comp), alloc)
461 explicit sorted_vector_map(
462 std::initializer_list<value_type> list,
463 const Compare& comp = Compare(),
464 const Allocator& alloc = Allocator())
465 : m_(value_compare(comp), alloc)
467 insert(list.begin(), list.end());
470 key_compare key_comp() const { return m_; }
471 value_compare value_comp() const { return m_; }
473 iterator begin() { return m_.cont_.begin(); }
474 iterator end() { return m_.cont_.end(); }
475 const_iterator cbegin() const { return m_.cont_.cbegin(); }
476 const_iterator begin() const { return m_.cont_.begin(); }
477 const_iterator cend() const { return m_.cont_.cend(); }
478 const_iterator end() const { return m_.cont_.end(); }
479 reverse_iterator rbegin() { return m_.cont_.rbegin(); }
480 reverse_iterator rend() { return m_.cont_.rend(); }
481 const_reverse_iterator rbegin() const { return m_.cont_.rbegin(); }
482 const_reverse_iterator rend() const { return m_.cont_.rend(); }
484 void clear() { return m_.cont_.clear(); }
485 size_type size() const { return m_.cont_.size(); }
486 size_type max_size() const { return m_.cont_.max_size(); }
487 bool empty() const { return m_.cont_.empty(); }
488 void reserve(size_type s) { return m_.cont_.reserve(s); }
489 void shrink_to_fit() { m_.cont_.shrink_to_fit(); }
490 size_type capacity() const { return m_.cont_.capacity(); }
492 std::pair<iterator,bool> insert(const value_type& value) {
493 return insert(std::move(value_type(value)));
496 std::pair<iterator,bool> insert(value_type&& value) {
497 iterator it = lower_bound(value.first);
498 if (it == end() || value_comp()(value, *it)) {
499 it = get_growth_policy().increase_capacity(m_.cont_, it);
500 return std::make_pair(m_.cont_.insert(it, std::move(value)), true);
502 return std::make_pair(it, false);
505 iterator insert(iterator hint, const value_type& value) {
506 return insert(hint, std::move(value_type(value)));
509 iterator insert(iterator hint, value_type&& value) {
510 return detail::insert_with_hint(*this, m_.cont_, hint, std::move(value),
511 get_growth_policy());
514 template<class InputIterator>
515 void insert(InputIterator first, InputIterator last) {
516 int d = detail::distance_if_multipass(first, last);
518 m_.cont_.reserve(m_.cont_.size() + d);
520 for (; first != last; ++first) {
521 insert(end(), *first);
525 size_type erase(const key_type& key) {
526 iterator it = find(key);
534 void erase(iterator it) {
538 void erase(iterator first, iterator last) {
539 m_.cont_.erase(first, last);
542 iterator find(const key_type& key) {
543 iterator it = lower_bound(key);
544 if (it == end() || !key_comp()(key, it->first))
549 const_iterator find(const key_type& key) const {
550 const_iterator it = lower_bound(key);
551 if (it == end() || !key_comp()(key, it->first))
556 mapped_type& at(const key_type& key) {
557 iterator it = find(key);
561 throw std::out_of_range("sorted_vector_map::at");
564 const mapped_type& at(const key_type& key) const {
565 const_iterator it = find(key);
569 throw std::out_of_range("sorted_vector_map::at");
572 size_type count(const key_type& key) const {
573 return find(key) == end() ? 0 : 1;
576 iterator lower_bound(const key_type& key) {
578 auto f = [&](const value_type& a, const key_type& b) {
579 return c(a.first, b);
581 return std::lower_bound(begin(), end(), key, f);
584 const_iterator lower_bound(const key_type& key) const {
586 auto f = [&](const value_type& a, const key_type& b) {
587 return c(a.first, b);
589 return std::lower_bound(begin(), end(), key, f);
592 iterator upper_bound(const key_type& key) {
594 auto f = [&](const key_type& a, const value_type& b) {
595 return c(a, b.first);
597 return std::upper_bound(begin(), end(), key, f);
600 const_iterator upper_bound(const key_type& key) const {
602 auto f = [&](const key_type& a, const value_type& b) {
603 return c(a, b.first);
605 return std::upper_bound(begin(), end(), key, f);
608 std::pair<iterator,iterator> equal_range(const key_type& key) {
609 // Note: std::equal_range can't be passed a functor that takes
610 // argument types different from the iterator value_type, so we
612 iterator low = lower_bound(key);
614 auto f = [&](const key_type& a, const value_type& b) {
615 return c(a, b.first);
617 iterator high = std::upper_bound(low, end(), key, f);
618 return std::make_pair(low, high);
621 std::pair<const_iterator,const_iterator>
622 equal_range(const key_type& key) const {
623 return const_cast<sorted_vector_map*>(this)->equal_range(key);
626 // Nothrow as long as swap() on the Compare type is nothrow.
627 void swap(sorted_vector_map& o) {
628 using std::swap; // Allow ADL for swap(); fall back to std::swap().
632 m_.cont_.swap(o.m_.cont_);
635 mapped_type& operator[](const key_type& key) {
636 iterator it = lower_bound(key);
637 if (it == end() || key_comp()(key, it->first)) {
638 return insert(it, value_type(key, mapped_type()))->second;
643 bool operator==(const sorted_vector_map& other) const {
644 return m_.cont_ == other.m_.cont_;
647 bool operator<(const sorted_vector_map& other) const {
648 return m_.cont_ < other.m_.cont_;
652 // This is to get the empty base optimization; see the comment in
653 // sorted_vector_set.
654 struct EBO : value_compare {
655 explicit EBO(const value_compare& c, const Allocator& alloc)
663 // Swap function that can be found using ADL.
664 template<class K, class V, class C, class A, class G>
665 inline void swap(sorted_vector_map<K,V,C,A,G>& a,
666 sorted_vector_map<K,V,C,A,G>& b) {
670 //////////////////////////////////////////////////////////////////////