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.
150 //////////////////////////////////////////////////////////////////////
153 * A sorted_vector_set is a container similar to std::set<>, but
154 * implemented as as a sorted array with std::vector<>.
156 * @param class T Data type to store
157 * @param class Compare Comparison function that imposes a
158 * strict weak ordering over instances of T
159 * @param class Allocator allocation policy
160 * @param class GrowthPolicy policy object to control growth
162 * @author Aditya Agarwal <aditya@fb.com>
163 * @author Akhil Wable <akhil@fb.com>
164 * @author Jordan DeLong <delong.j@fb.com>
167 class Compare = std::less<T>,
168 class Allocator = std::allocator<T>,
169 class GrowthPolicy = void>
170 class sorted_vector_set
171 : boost::totally_ordered1<
172 sorted_vector_set<T,Compare,Allocator,GrowthPolicy>
173 , detail::growth_policy_wrapper<GrowthPolicy> >
175 typedef std::vector<T,Allocator> ContainerT;
177 detail::growth_policy_wrapper<GrowthPolicy>&
178 get_growth_policy() { return *this; }
181 typedef T value_type;
183 typedef Compare key_compare;
184 typedef Compare value_compare;
186 typedef typename ContainerT::pointer pointer;
187 typedef typename ContainerT::reference reference;
188 typedef typename ContainerT::const_reference const_reference;
190 * XXX: Our normal iterator ought to also be a constant iterator
191 * (cf. Defect Report 103 for std::set), but this is a bit more of a
194 typedef typename ContainerT::iterator iterator;
195 typedef typename ContainerT::const_iterator const_iterator;
196 typedef typename ContainerT::difference_type difference_type;
197 typedef typename ContainerT::size_type size_type;
198 typedef typename ContainerT::reverse_iterator reverse_iterator;
199 typedef typename ContainerT::const_reverse_iterator const_reverse_iterator;
201 explicit sorted_vector_set(const Compare& comp = Compare(),
202 const Allocator& alloc = Allocator())
206 template<class InputIterator>
207 explicit sorted_vector_set(
210 const Compare& comp = Compare(),
211 const Allocator& alloc = Allocator())
214 // This is linear if [first, last) is already sorted (and if we
215 // can figure out the distance between the two iterators).
219 /* implicit */ sorted_vector_set(
220 std::initializer_list<value_type> list,
221 const Compare& comp = Compare(),
222 const Allocator& alloc = Allocator())
225 insert(list.begin(), list.end());
228 key_compare key_comp() const { return m_; }
229 value_compare value_comp() const { return m_; }
231 iterator begin() { return m_.cont_.begin(); }
232 iterator end() { return m_.cont_.end(); }
233 const_iterator cbegin() const { return m_.cont_.cbegin(); }
234 const_iterator begin() const { return m_.cont_.begin(); }
235 const_iterator cend() const { return m_.cont_.cend(); }
236 const_iterator end() const { return m_.cont_.end(); }
237 reverse_iterator rbegin() { return m_.cont_.rbegin(); }
238 reverse_iterator rend() { return m_.cont_.rend(); }
239 const_reverse_iterator rbegin() const { return m_.cont_.rbegin(); }
240 const_reverse_iterator rend() const { return m_.cont_.rend(); }
242 void clear() { return m_.cont_.clear(); }
243 size_type size() const { return m_.cont_.size(); }
244 size_type max_size() const { return m_.cont_.max_size(); }
245 bool empty() const { return m_.cont_.empty(); }
246 void reserve(size_type s) { return m_.cont_.reserve(s); }
247 void shrink_to_fit() { m_.cont_.shrink_to_fit(); }
248 size_type capacity() const { return m_.cont_.capacity(); }
250 std::pair<iterator,bool> insert(const value_type& value) {
251 return insert(std::move(value_type(value)));
254 std::pair<iterator,bool> insert(value_type&& value) {
255 iterator it = lower_bound(value);
256 if (it == end() || value_comp()(value, *it)) {
257 it = get_growth_policy().increase_capacity(m_.cont_, it);
258 return std::make_pair(m_.cont_.insert(it, std::move(value)), true);
260 return std::make_pair(it, false);
263 iterator insert(iterator hint, const value_type& value) {
264 return insert(hint, std::move(value_type(value)));
267 iterator insert(iterator hint, value_type&& value) {
268 return detail::insert_with_hint(*this, m_.cont_, hint, std::move(value),
269 get_growth_policy());
272 template<class InputIterator>
273 void insert(InputIterator first, InputIterator last) {
274 int d = detail::distance_if_multipass(first, last);
276 m_.cont_.reserve(m_.cont_.size() + d);
278 for (; first != last; ++first) {
279 insert(end(), *first);
283 size_type erase(const key_type& key) {
284 iterator it = find(key);
292 void erase(iterator it) {
296 void erase(iterator first, iterator last) {
297 m_.cont_.erase(first, last);
300 iterator find(const key_type& key) {
301 iterator it = lower_bound(key);
302 if (it == end() || !key_comp()(key, *it))
307 const_iterator find(const key_type& key) const {
308 const_iterator it = lower_bound(key);
309 if (it == end() || !key_comp()(key, *it))
314 size_type count(const key_type& key) const {
315 return find(key) == end() ? 0 : 1;
318 iterator lower_bound(const key_type& key) {
319 return std::lower_bound(begin(), end(), key, key_comp());
322 const_iterator lower_bound(const key_type& key) const {
323 return std::lower_bound(begin(), end(), key, key_comp());
326 iterator upper_bound(const key_type& key) {
327 return std::upper_bound(begin(), end(), key, key_comp());
330 const_iterator upper_bound(const key_type& key) const {
331 return std::upper_bound(begin(), end(), key, key_comp());
334 std::pair<iterator,iterator> equal_range(const key_type& key) {
335 return std::equal_range(begin(), end(), key, key_comp());
338 std::pair<const_iterator,const_iterator>
339 equal_range(const key_type& key) const {
340 return std::equal_range(begin(), end(), key, key_comp());
343 // Nothrow as long as swap() on the Compare type is nothrow.
344 void swap(sorted_vector_set& o) {
345 using std::swap; // Allow ADL for swap(); fall back to std::swap().
349 m_.cont_.swap(o.m_.cont_);
352 bool operator==(const sorted_vector_set& other) const {
353 return other.m_.cont_ == m_.cont_;
356 bool operator<(const sorted_vector_set& other) const {
357 return m_.cont_ < other.m_.cont_;
362 * This structure derives from the comparison object in order to
363 * make use of the empty base class optimization if our comparison
364 * functor is an empty class (usual case).
366 * Wrapping up this member like this is better than deriving from
367 * the Compare object ourselves (there are some perverse edge cases
368 * involving virtual functions).
370 * More info: http://www.cantrip.org/emptyopt.html
372 struct EBO : Compare {
373 explicit EBO(const Compare& c, const Allocator& alloc)
381 // Swap function that can be found using ADL.
382 template<class T, class C, class A, class G>
383 inline void swap(sorted_vector_set<T,C,A,G>& a,
384 sorted_vector_set<T,C,A,G>& b) {
388 //////////////////////////////////////////////////////////////////////
391 * A sorted_vector_map is similar to a sorted_vector_set but stores
392 * <key,value> pairs instead of single elements.
394 * @param class Key Key type
395 * @param class Value Value type
396 * @param class Compare Function that can compare key types and impose
397 * a strict weak ordering over them.
398 * @param class Allocator allocation policy
399 * @param class GrowthPolicy policy object to control growth
401 * @author Aditya Agarwal <aditya@fb.com>
402 * @author Akhil Wable <akhil@fb.com>
403 * @author Jordan DeLong <delong.j@fb.com>
407 class Compare = std::less<Key>,
408 class Allocator = std::allocator<std::pair<Key,Value> >,
409 class GrowthPolicy = void>
410 class sorted_vector_map
411 : boost::totally_ordered1<
412 sorted_vector_map<Key,Value,Compare,Allocator,GrowthPolicy>
413 , detail::growth_policy_wrapper<GrowthPolicy> >
415 typedef std::vector<std::pair<Key,Value>,Allocator> ContainerT;
417 detail::growth_policy_wrapper<GrowthPolicy>&
418 get_growth_policy() { return *this; }
421 typedef Key key_type;
422 typedef Value mapped_type;
423 typedef std::pair<key_type,mapped_type> value_type;
424 typedef Compare key_compare;
426 struct value_compare : private Compare {
427 bool operator()(const value_type& a, const value_type& b) const {
428 return Compare::operator()(a.first, b.first);
432 friend class sorted_vector_map;
433 explicit value_compare(const Compare& c) : Compare(c) {}
436 typedef typename ContainerT::pointer pointer;
437 typedef typename ContainerT::reference reference;
438 typedef typename ContainerT::const_reference const_reference;
439 typedef typename ContainerT::iterator iterator;
440 typedef typename ContainerT::const_iterator const_iterator;
441 typedef typename ContainerT::difference_type difference_type;
442 typedef typename ContainerT::size_type size_type;
443 typedef typename ContainerT::reverse_iterator reverse_iterator;
444 typedef typename ContainerT::const_reverse_iterator const_reverse_iterator;
446 explicit sorted_vector_map(const Compare& comp = Compare(),
447 const Allocator& alloc = Allocator())
448 : m_(value_compare(comp), alloc)
451 template<class InputIterator>
452 explicit sorted_vector_map(
455 const Compare& comp = Compare(),
456 const Allocator& alloc = Allocator())
457 : m_(value_compare(comp), alloc)
462 explicit sorted_vector_map(
463 std::initializer_list<value_type> list,
464 const Compare& comp = Compare(),
465 const Allocator& alloc = Allocator())
466 : m_(value_compare(comp), alloc)
468 insert(list.begin(), list.end());
471 key_compare key_comp() const { return m_; }
472 value_compare value_comp() const { return m_; }
474 iterator begin() { return m_.cont_.begin(); }
475 iterator end() { return m_.cont_.end(); }
476 const_iterator cbegin() const { return m_.cont_.cbegin(); }
477 const_iterator begin() const { return m_.cont_.begin(); }
478 const_iterator cend() const { return m_.cont_.cend(); }
479 const_iterator end() const { return m_.cont_.end(); }
480 reverse_iterator rbegin() { return m_.cont_.rbegin(); }
481 reverse_iterator rend() { return m_.cont_.rend(); }
482 const_reverse_iterator rbegin() const { return m_.cont_.rbegin(); }
483 const_reverse_iterator rend() const { return m_.cont_.rend(); }
485 void clear() { return m_.cont_.clear(); }
486 size_type size() const { return m_.cont_.size(); }
487 size_type max_size() const { return m_.cont_.max_size(); }
488 bool empty() const { return m_.cont_.empty(); }
489 void reserve(size_type s) { return m_.cont_.reserve(s); }
490 void shrink_to_fit() { m_.cont_.shrink_to_fit(); }
491 size_type capacity() const { return m_.cont_.capacity(); }
493 std::pair<iterator,bool> insert(const value_type& value) {
494 return insert(std::move(value_type(value)));
497 std::pair<iterator,bool> insert(value_type&& value) {
498 iterator it = lower_bound(value.first);
499 if (it == end() || value_comp()(value, *it)) {
500 it = get_growth_policy().increase_capacity(m_.cont_, it);
501 return std::make_pair(m_.cont_.insert(it, std::move(value)), true);
503 return std::make_pair(it, false);
506 iterator insert(iterator hint, const value_type& value) {
507 return insert(hint, std::move(value_type(value)));
510 iterator insert(iterator hint, value_type&& value) {
511 return detail::insert_with_hint(*this, m_.cont_, hint, std::move(value),
512 get_growth_policy());
515 template<class InputIterator>
516 void insert(InputIterator first, InputIterator last) {
517 int d = detail::distance_if_multipass(first, last);
519 m_.cont_.reserve(m_.cont_.size() + d);
521 for (; first != last; ++first) {
522 insert(end(), *first);
526 size_type erase(const key_type& key) {
527 iterator it = find(key);
535 void erase(iterator it) {
539 void erase(iterator first, iterator last) {
540 m_.cont_.erase(first, last);
543 iterator find(const key_type& key) {
544 iterator it = lower_bound(key);
545 if (it == end() || !key_comp()(key, it->first))
550 const_iterator find(const key_type& key) const {
551 const_iterator it = lower_bound(key);
552 if (it == end() || !key_comp()(key, it->first))
557 mapped_type& at(const key_type& key) {
558 iterator it = find(key);
562 std::__throw_out_of_range("sorted_vector_map::at");
565 const mapped_type& at(const key_type& key) const {
566 const_iterator it = find(key);
570 std::__throw_out_of_range("sorted_vector_map::at");
573 size_type count(const key_type& key) const {
574 return find(key) == end() ? 0 : 1;
577 iterator lower_bound(const key_type& key) {
579 auto f = [&](const value_type& a, const key_type& b) {
580 return c(a.first, b);
582 return std::lower_bound(begin(), end(), key, f);
585 const_iterator lower_bound(const key_type& key) const {
587 auto f = [&](const value_type& a, const key_type& b) {
588 return c(a.first, b);
590 return std::lower_bound(begin(), end(), key, f);
593 iterator upper_bound(const key_type& key) {
595 auto f = [&](const key_type& a, const value_type& b) {
596 return c(a, b.first);
598 return std::upper_bound(begin(), end(), key, f);
601 const_iterator upper_bound(const key_type& key) const {
603 auto f = [&](const key_type& a, const value_type& b) {
604 return c(a, b.first);
606 return std::upper_bound(begin(), end(), key, f);
609 std::pair<iterator,iterator> equal_range(const key_type& key) {
610 // Note: std::equal_range can't be passed a functor that takes
611 // argument types different from the iterator value_type, so we
613 iterator low = lower_bound(key);
615 auto f = [&](const key_type& a, const value_type& b) {
616 return c(a, b.first);
618 iterator high = std::upper_bound(low, end(), key, f);
619 return std::make_pair(low, high);
622 std::pair<const_iterator,const_iterator>
623 equal_range(const key_type& key) const {
624 return const_cast<sorted_vector_map*>(this)->equal_range(key);
627 // Nothrow as long as swap() on the Compare type is nothrow.
628 void swap(sorted_vector_map& o) {
629 using std::swap; // Allow ADL for swap(); fall back to std::swap().
633 m_.cont_.swap(o.m_.cont_);
636 mapped_type& operator[](const key_type& key) {
637 iterator it = lower_bound(key);
638 if (it == end() || key_comp()(key, it->first)) {
639 return insert(it, value_type(key, mapped_type()))->second;
644 bool operator==(const sorted_vector_map& other) const {
645 return m_.cont_ == other.m_.cont_;
648 bool operator<(const sorted_vector_map& other) const {
649 return m_.cont_ < other.m_.cont_;
653 // This is to get the empty base optimization; see the comment in
654 // sorted_vector_set.
655 struct EBO : value_compare {
656 explicit EBO(const value_compare& c, const Allocator& alloc)
664 // Swap function that can be found using ADL.
665 template<class K, class V, class C, class A, class G>
666 inline void swap(sorted_vector_map<K,V,C,A,G>& a,
667 sorted_vector_map<K,V,C,A,G>& b) {
671 //////////////////////////////////////////////////////////////////////