1// Copyright 2017 The Abseil Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14//
15// -----------------------------------------------------------------------------
16// File: container.h
17// -----------------------------------------------------------------------------
18//
19// This header file provides Container-based versions of algorithmic functions
20// within the C++ standard library. The following standard library sets of
21// functions are covered within this file:
22//
23// * Algorithmic <iterator> functions
24// * Algorithmic <numeric> functions
25// * <algorithm> functions
26//
27// The standard library functions operate on iterator ranges; the functions
28// within this API operate on containers, though many return iterator ranges.
29//
30// All functions within this API are named with a `c_` prefix. Calls such as
31// `absl::c_xx(container, ...) are equivalent to std:: functions such as
32// `std::xx(std::begin(cont), std::end(cont), ...)`. Functions that act on
33// iterators but not conceptually on iterator ranges (e.g. `std::iter_swap`)
34// have no equivalent here.
35//
36// For template parameter and variable naming, `C` indicates the container type
37// to which the function is applied, `Pred` indicates the predicate object type
38// to be used by the function and `T` indicates the applicable element type.
39
40#ifndef ABSL_ALGORITHM_CONTAINER_H_
41#define ABSL_ALGORITHM_CONTAINER_H_
42
43#include <algorithm>
44#include <cassert>
45#include <iterator>
46#include <numeric>
47#include <type_traits>
48#include <unordered_map>
49#include <unordered_set>
50#include <utility>
51#include <vector>
52
53#include "absl/algorithm/algorithm.h"
54#include "absl/base/macros.h"
55#include "absl/meta/type_traits.h"
56
57namespace absl {
58ABSL_NAMESPACE_BEGIN
59namespace container_algorithm_internal {
60
61// NOTE: it is important to defer to ADL lookup for building with C++ modules,
62// especially for headers like <valarray> which are not visible from this file
63// but specialize std::begin and std::end.
64using std::begin;
65using std::end;
66
67// The type of the iterator given by begin(c) (possibly std::begin(c)).
68// ContainerIter<const vector<T>> gives vector<T>::const_iterator,
69// while ContainerIter<vector<T>> gives vector<T>::iterator.
70template <typename C>
71using ContainerIter = decltype(begin(std::declval<C&>()));
72
73// An MSVC bug involving template parameter substitution requires us to use
74// decltype() here instead of just std::pair.
75template <typename C1, typename C2>
76using ContainerIterPairType =
77 decltype(std::make_pair(ContainerIter<C1>(), ContainerIter<C2>()));
78
79template <typename C>
80using ContainerDifferenceType =
81 decltype(std::distance(std::declval<ContainerIter<C>>(),
82 std::declval<ContainerIter<C>>()));
83
84template <typename C>
85using ContainerPointerType =
86 typename std::iterator_traits<ContainerIter<C>>::pointer;
87
88// container_algorithm_internal::c_begin and
89// container_algorithm_internal::c_end are abbreviations for proper ADL
90// lookup of std::begin and std::end, i.e.
91// using std::begin;
92// using std::end;
93// std::foo(begin(c), end(c));
94// becomes
95// std::foo(container_algorithm_internal::begin(c),
96// container_algorithm_internal::end(c));
97// These are meant for internal use only.
98
99template <typename C>
100ContainerIter<C> c_begin(C& c) { return begin(c); }
101
102template <typename C>
103ContainerIter<C> c_end(C& c) { return end(c); }
104
105template <typename T>
106struct IsUnorderedContainer : std::false_type {};
107
108template <class Key, class T, class Hash, class KeyEqual, class Allocator>
109struct IsUnorderedContainer<
110 std::unordered_map<Key, T, Hash, KeyEqual, Allocator>> : std::true_type {};
111
112template <class Key, class Hash, class KeyEqual, class Allocator>
113struct IsUnorderedContainer<std::unordered_set<Key, Hash, KeyEqual, Allocator>>
114 : std::true_type {};
115
116// container_algorithm_internal::c_size. It is meant for internal use only.
117
118template <class C>
119auto c_size(C& c) -> decltype(c.size()) {
120 return c.size();
121}
122
123template <class T, std::size_t N>
124constexpr std::size_t c_size(T (&)[N]) {
125 return N;
126}
127
128} // namespace container_algorithm_internal
129
130// PUBLIC API
131
132//------------------------------------------------------------------------------
133// Abseil algorithm.h functions
134//------------------------------------------------------------------------------
135
136// c_linear_search()
137//
138// Container-based version of absl::linear_search() for performing a linear
139// search within a container.
140template <typename C, typename EqualityComparable>
141bool c_linear_search(const C& c, EqualityComparable&& value) {
142 return linear_search(container_algorithm_internal::c_begin(c),
143 container_algorithm_internal::c_end(c),
144 std::forward<EqualityComparable>(value));
145}
146
147//------------------------------------------------------------------------------
148// <iterator> algorithms
149//------------------------------------------------------------------------------
150
151// c_distance()
152//
153// Container-based version of the <iterator> `std::distance()` function to
154// return the number of elements within a container.
155template <typename C>
156container_algorithm_internal::ContainerDifferenceType<const C> c_distance(
157 const C& c) {
158 return std::distance(container_algorithm_internal::c_begin(c),
159 container_algorithm_internal::c_end(c));
160}
161
162//------------------------------------------------------------------------------
163// <algorithm> Non-modifying sequence operations
164//------------------------------------------------------------------------------
165
166// c_all_of()
167//
168// Container-based version of the <algorithm> `std::all_of()` function to
169// test if all elements within a container satisfy a condition.
170template <typename C, typename Pred>
171bool c_all_of(const C& c, Pred&& pred) {
172 return std::all_of(container_algorithm_internal::c_begin(c),
173 container_algorithm_internal::c_end(c),
174 std::forward<Pred>(pred));
175}
176
177// c_any_of()
178//
179// Container-based version of the <algorithm> `std::any_of()` function to
180// test if any element in a container fulfills a condition.
181template <typename C, typename Pred>
182bool c_any_of(const C& c, Pred&& pred) {
183 return std::any_of(container_algorithm_internal::c_begin(c),
184 container_algorithm_internal::c_end(c),
185 std::forward<Pred>(pred));
186}
187
188// c_none_of()
189//
190// Container-based version of the <algorithm> `std::none_of()` function to
191// test if no elements in a container fulfill a condition.
192template <typename C, typename Pred>
193bool c_none_of(const C& c, Pred&& pred) {
194 return std::none_of(container_algorithm_internal::c_begin(c),
195 container_algorithm_internal::c_end(c),
196 std::forward<Pred>(pred));
197}
198
199// c_for_each()
200//
201// Container-based version of the <algorithm> `std::for_each()` function to
202// apply a function to a container's elements.
203template <typename C, typename Function>
204decay_t<Function> c_for_each(C&& c, Function&& f) {
205 return std::for_each(container_algorithm_internal::c_begin(c),
206 container_algorithm_internal::c_end(c),
207 std::forward<Function>(f));
208}
209
210// c_find()
211//
212// Container-based version of the <algorithm> `std::find()` function to find
213// the first element containing the passed value within a container value.
214template <typename C, typename T>
215container_algorithm_internal::ContainerIter<C> c_find(C& c, T&& value) {
216 return std::find(container_algorithm_internal::c_begin(c),
217 container_algorithm_internal::c_end(c),
218 std::forward<T>(value));
219}
220
221// c_find_if()
222//
223// Container-based version of the <algorithm> `std::find_if()` function to find
224// the first element in a container matching the given condition.
225template <typename C, typename Pred>
226container_algorithm_internal::ContainerIter<C> c_find_if(C& c, Pred&& pred) {
227 return std::find_if(container_algorithm_internal::c_begin(c),
228 container_algorithm_internal::c_end(c),
229 std::forward<Pred>(pred));
230}
231
232// c_find_if_not()
233//
234// Container-based version of the <algorithm> `std::find_if_not()` function to
235// find the first element in a container not matching the given condition.
236template <typename C, typename Pred>
237container_algorithm_internal::ContainerIter<C> c_find_if_not(C& c,
238 Pred&& pred) {
239 return std::find_if_not(container_algorithm_internal::c_begin(c),
240 container_algorithm_internal::c_end(c),
241 std::forward<Pred>(pred));
242}
243
244// c_find_end()
245//
246// Container-based version of the <algorithm> `std::find_end()` function to
247// find the last subsequence within a container.
248template <typename Sequence1, typename Sequence2>
249container_algorithm_internal::ContainerIter<Sequence1> c_find_end(
250 Sequence1& sequence, Sequence2& subsequence) {
251 return std::find_end(container_algorithm_internal::c_begin(sequence),
252 container_algorithm_internal::c_end(sequence),
253 container_algorithm_internal::c_begin(subsequence),
254 container_algorithm_internal::c_end(subsequence));
255}
256
257// Overload of c_find_end() for using a predicate evaluation other than `==` as
258// the function's test condition.
259template <typename Sequence1, typename Sequence2, typename BinaryPredicate>
260container_algorithm_internal::ContainerIter<Sequence1> c_find_end(
261 Sequence1& sequence, Sequence2& subsequence, BinaryPredicate&& pred) {
262 return std::find_end(container_algorithm_internal::c_begin(sequence),
263 container_algorithm_internal::c_end(sequence),
264 container_algorithm_internal::c_begin(subsequence),
265 container_algorithm_internal::c_end(subsequence),
266 std::forward<BinaryPredicate>(pred));
267}
268
269// c_find_first_of()
270//
271// Container-based version of the <algorithm> `std::find_first_of()` function to
272// find the first element within the container that is also within the options
273// container.
274template <typename C1, typename C2>
275container_algorithm_internal::ContainerIter<C1> c_find_first_of(C1& container,
276 C2& options) {
277 return std::find_first_of(container_algorithm_internal::c_begin(container),
278 container_algorithm_internal::c_end(container),
279 container_algorithm_internal::c_begin(options),
280 container_algorithm_internal::c_end(options));
281}
282
283// Overload of c_find_first_of() for using a predicate evaluation other than
284// `==` as the function's test condition.
285template <typename C1, typename C2, typename BinaryPredicate>
286container_algorithm_internal::ContainerIter<C1> c_find_first_of(
287 C1& container, C2& options, BinaryPredicate&& pred) {
288 return std::find_first_of(container_algorithm_internal::c_begin(container),
289 container_algorithm_internal::c_end(container),
290 container_algorithm_internal::c_begin(options),
291 container_algorithm_internal::c_end(options),
292 std::forward<BinaryPredicate>(pred));
293}
294
295// c_adjacent_find()
296//
297// Container-based version of the <algorithm> `std::adjacent_find()` function to
298// find equal adjacent elements within a container.
299template <typename Sequence>
300container_algorithm_internal::ContainerIter<Sequence> c_adjacent_find(
301 Sequence& sequence) {
302 return std::adjacent_find(container_algorithm_internal::c_begin(sequence),
303 container_algorithm_internal::c_end(sequence));
304}
305
306// Overload of c_adjacent_find() for using a predicate evaluation other than
307// `==` as the function's test condition.
308template <typename Sequence, typename BinaryPredicate>
309container_algorithm_internal::ContainerIter<Sequence> c_adjacent_find(
310 Sequence& sequence, BinaryPredicate&& pred) {
311 return std::adjacent_find(container_algorithm_internal::c_begin(sequence),
312 container_algorithm_internal::c_end(sequence),
313 std::forward<BinaryPredicate>(pred));
314}
315
316// c_count()
317//
318// Container-based version of the <algorithm> `std::count()` function to count
319// values that match within a container.
320template <typename C, typename T>
321container_algorithm_internal::ContainerDifferenceType<const C> c_count(
322 const C& c, T&& value) {
323 return std::count(container_algorithm_internal::c_begin(c),
324 container_algorithm_internal::c_end(c),
325 std::forward<T>(value));
326}
327
328// c_count_if()
329//
330// Container-based version of the <algorithm> `std::count_if()` function to
331// count values matching a condition within a container.
332template <typename C, typename Pred>
333container_algorithm_internal::ContainerDifferenceType<const C> c_count_if(
334 const C& c, Pred&& pred) {
335 return std::count_if(container_algorithm_internal::c_begin(c),
336 container_algorithm_internal::c_end(c),
337 std::forward<Pred>(pred));
338}
339
340// c_mismatch()
341//
342// Container-based version of the <algorithm> `std::mismatch()` function to
343// return the first element where two ordered containers differ. Applies `==` to
344// the first N elements of `c1` and `c2`, where N = min(size(c1), size(c2)).
345template <typename C1, typename C2>
346container_algorithm_internal::ContainerIterPairType<C1, C2>
347c_mismatch(C1& c1, C2& c2) {
348 auto first1 = container_algorithm_internal::c_begin(c1);
349 auto last1 = container_algorithm_internal::c_end(c1);
350 auto first2 = container_algorithm_internal::c_begin(c2);
351 auto last2 = container_algorithm_internal::c_end(c2);
352
353 for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) {
354 // Negates equality because Cpp17EqualityComparable doesn't require clients
355 // to overload both `operator==` and `operator!=`.
356 if (!(*first1 == *first2)) {
357 break;
358 }
359 }
360
361 return std::make_pair(first1, first2);
362}
363
364// Overload of c_mismatch() for using a predicate evaluation other than `==` as
365// the function's test condition. Applies `pred`to the first N elements of `c1`
366// and `c2`, where N = min(size(c1), size(c2)).
367template <typename C1, typename C2, typename BinaryPredicate>
368container_algorithm_internal::ContainerIterPairType<C1, C2>
369c_mismatch(C1& c1, C2& c2, BinaryPredicate pred) {
370 auto first1 = container_algorithm_internal::c_begin(c1);
371 auto last1 = container_algorithm_internal::c_end(c1);
372 auto first2 = container_algorithm_internal::c_begin(c2);
373 auto last2 = container_algorithm_internal::c_end(c2);
374
375 for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) {
376 if (!pred(*first1, *first2)) {
377 break;
378 }
379 }
380
381 return std::make_pair(first1, first2);
382}
383
384// c_equal()
385//
386// Container-based version of the <algorithm> `std::equal()` function to
387// test whether two containers are equal.
388//
389// NOTE: the semantics of c_equal() are slightly different than those of
390// equal(): while the latter iterates over the second container only up to the
391// size of the first container, c_equal() also checks whether the container
392// sizes are equal. This better matches expectations about c_equal() based on
393// its signature.
394//
395// Example:
396// vector v1 = <1, 2, 3>;
397// vector v2 = <1, 2, 3, 4>;
398// equal(std::begin(v1), std::end(v1), std::begin(v2)) returns true
399// c_equal(v1, v2) returns false
400
401template <typename C1, typename C2>
402bool c_equal(const C1& c1, const C2& c2) {
403 return ((container_algorithm_internal::c_size(c1) ==
404 container_algorithm_internal::c_size(c2)) &&
405 std::equal(container_algorithm_internal::c_begin(c1),
406 container_algorithm_internal::c_end(c1),
407 container_algorithm_internal::c_begin(c2)));
408}
409
410// Overload of c_equal() for using a predicate evaluation other than `==` as
411// the function's test condition.
412template <typename C1, typename C2, typename BinaryPredicate>
413bool c_equal(const C1& c1, const C2& c2, BinaryPredicate&& pred) {
414 return ((container_algorithm_internal::c_size(c1) ==
415 container_algorithm_internal::c_size(c2)) &&
416 std::equal(container_algorithm_internal::c_begin(c1),
417 container_algorithm_internal::c_end(c1),
418 container_algorithm_internal::c_begin(c2),
419 std::forward<BinaryPredicate>(pred)));
420}
421
422// c_is_permutation()
423//
424// Container-based version of the <algorithm> `std::is_permutation()` function
425// to test whether a container is a permutation of another.
426template <typename C1, typename C2>
427bool c_is_permutation(const C1& c1, const C2& c2) {
428 using std::begin;
429 using std::end;
430 return c1.size() == c2.size() &&
431 std::is_permutation(begin(c1), end(c1), begin(c2));
432}
433
434// Overload of c_is_permutation() for using a predicate evaluation other than
435// `==` as the function's test condition.
436template <typename C1, typename C2, typename BinaryPredicate>
437bool c_is_permutation(const C1& c1, const C2& c2, BinaryPredicate&& pred) {
438 using std::begin;
439 using std::end;
440 return c1.size() == c2.size() &&
441 std::is_permutation(begin(c1), end(c1), begin(c2),
442 std::forward<BinaryPredicate>(pred));
443}
444
445// c_search()
446//
447// Container-based version of the <algorithm> `std::search()` function to search
448// a container for a subsequence.
449template <typename Sequence1, typename Sequence2>
450container_algorithm_internal::ContainerIter<Sequence1> c_search(
451 Sequence1& sequence, Sequence2& subsequence) {
452 return std::search(container_algorithm_internal::c_begin(sequence),
453 container_algorithm_internal::c_end(sequence),
454 container_algorithm_internal::c_begin(subsequence),
455 container_algorithm_internal::c_end(subsequence));
456}
457
458// Overload of c_search() for using a predicate evaluation other than
459// `==` as the function's test condition.
460template <typename Sequence1, typename Sequence2, typename BinaryPredicate>
461container_algorithm_internal::ContainerIter<Sequence1> c_search(
462 Sequence1& sequence, Sequence2& subsequence, BinaryPredicate&& pred) {
463 return std::search(container_algorithm_internal::c_begin(sequence),
464 container_algorithm_internal::c_end(sequence),
465 container_algorithm_internal::c_begin(subsequence),
466 container_algorithm_internal::c_end(subsequence),
467 std::forward<BinaryPredicate>(pred));
468}
469
470// c_search_n()
471//
472// Container-based version of the <algorithm> `std::search_n()` function to
473// search a container for the first sequence of N elements.
474template <typename Sequence, typename Size, typename T>
475container_algorithm_internal::ContainerIter<Sequence> c_search_n(
476 Sequence& sequence, Size count, T&& value) {
477 return std::search_n(container_algorithm_internal::c_begin(sequence),
478 container_algorithm_internal::c_end(sequence), count,
479 std::forward<T>(value));
480}
481
482// Overload of c_search_n() for using a predicate evaluation other than
483// `==` as the function's test condition.
484template <typename Sequence, typename Size, typename T,
485 typename BinaryPredicate>
486container_algorithm_internal::ContainerIter<Sequence> c_search_n(
487 Sequence& sequence, Size count, T&& value, BinaryPredicate&& pred) {
488 return std::search_n(container_algorithm_internal::c_begin(sequence),
489 container_algorithm_internal::c_end(sequence), count,
490 std::forward<T>(value),
491 std::forward<BinaryPredicate>(pred));
492}
493
494//------------------------------------------------------------------------------
495// <algorithm> Modifying sequence operations
496//------------------------------------------------------------------------------
497
498// c_copy()
499//
500// Container-based version of the <algorithm> `std::copy()` function to copy a
501// container's elements into an iterator.
502template <typename InputSequence, typename OutputIterator>
503OutputIterator c_copy(const InputSequence& input, OutputIterator output) {
504 return std::copy(container_algorithm_internal::c_begin(input),
505 container_algorithm_internal::c_end(input), output);
506}
507
508// c_copy_n()
509//
510// Container-based version of the <algorithm> `std::copy_n()` function to copy a
511// container's first N elements into an iterator.
512template <typename C, typename Size, typename OutputIterator>
513OutputIterator c_copy_n(const C& input, Size n, OutputIterator output) {
514 return std::copy_n(container_algorithm_internal::c_begin(input), n, output);
515}
516
517// c_copy_if()
518//
519// Container-based version of the <algorithm> `std::copy_if()` function to copy
520// a container's elements satisfying some condition into an iterator.
521template <typename InputSequence, typename OutputIterator, typename Pred>
522OutputIterator c_copy_if(const InputSequence& input, OutputIterator output,
523 Pred&& pred) {
524 return std::copy_if(container_algorithm_internal::c_begin(input),
525 container_algorithm_internal::c_end(input), output,
526 std::forward<Pred>(pred));
527}
528
529// c_copy_backward()
530//
531// Container-based version of the <algorithm> `std::copy_backward()` function to
532// copy a container's elements in reverse order into an iterator.
533template <typename C, typename BidirectionalIterator>
534BidirectionalIterator c_copy_backward(const C& src,
535 BidirectionalIterator dest) {
536 return std::copy_backward(container_algorithm_internal::c_begin(src),
537 container_algorithm_internal::c_end(src), dest);
538}
539
540// c_move()
541//
542// Container-based version of the <algorithm> `std::move()` function to move
543// a container's elements into an iterator.
544template <typename C, typename OutputIterator>
545OutputIterator c_move(C&& src, OutputIterator dest) {
546 return std::move(container_algorithm_internal::c_begin(src),
547 container_algorithm_internal::c_end(src), dest);
548}
549
550// c_move_backward()
551//
552// Container-based version of the <algorithm> `std::move_backward()` function to
553// move a container's elements into an iterator in reverse order.
554template <typename C, typename BidirectionalIterator>
555BidirectionalIterator c_move_backward(C&& src, BidirectionalIterator dest) {
556 return std::move_backward(container_algorithm_internal::c_begin(src),
557 container_algorithm_internal::c_end(src), dest);
558}
559
560// c_swap_ranges()
561//
562// Container-based version of the <algorithm> `std::swap_ranges()` function to
563// swap a container's elements with another container's elements. Swaps the
564// first N elements of `c1` and `c2`, where N = min(size(c1), size(c2)).
565template <typename C1, typename C2>
566container_algorithm_internal::ContainerIter<C2> c_swap_ranges(C1& c1, C2& c2) {
567 auto first1 = container_algorithm_internal::c_begin(c1);
568 auto last1 = container_algorithm_internal::c_end(c1);
569 auto first2 = container_algorithm_internal::c_begin(c2);
570 auto last2 = container_algorithm_internal::c_end(c2);
571
572 using std::swap;
573 for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) {
574 swap(*first1, *first2);
575 }
576 return first2;
577}
578
579// c_transform()
580//
581// Container-based version of the <algorithm> `std::transform()` function to
582// transform a container's elements using the unary operation, storing the
583// result in an iterator pointing to the last transformed element in the output
584// range.
585template <typename InputSequence, typename OutputIterator, typename UnaryOp>
586OutputIterator c_transform(const InputSequence& input, OutputIterator output,
587 UnaryOp&& unary_op) {
588 return std::transform(container_algorithm_internal::c_begin(input),
589 container_algorithm_internal::c_end(input), output,
590 std::forward<UnaryOp>(unary_op));
591}
592
593// Overload of c_transform() for performing a transformation using a binary
594// predicate. Applies `binary_op` to the first N elements of `c1` and `c2`,
595// where N = min(size(c1), size(c2)).
596template <typename InputSequence1, typename InputSequence2,
597 typename OutputIterator, typename BinaryOp>
598OutputIterator c_transform(const InputSequence1& input1,
599 const InputSequence2& input2, OutputIterator output,
600 BinaryOp&& binary_op) {
601 auto first1 = container_algorithm_internal::c_begin(input1);
602 auto last1 = container_algorithm_internal::c_end(input1);
603 auto first2 = container_algorithm_internal::c_begin(input2);
604 auto last2 = container_algorithm_internal::c_end(input2);
605 for (; first1 != last1 && first2 != last2;
606 ++first1, (void)++first2, ++output) {
607 *output = binary_op(*first1, *first2);
608 }
609
610 return output;
611}
612
613// c_replace()
614//
615// Container-based version of the <algorithm> `std::replace()` function to
616// replace a container's elements of some value with a new value. The container
617// is modified in place.
618template <typename Sequence, typename T>
619void c_replace(Sequence& sequence, const T& old_value, const T& new_value) {
620 std::replace(container_algorithm_internal::c_begin(sequence),
621 container_algorithm_internal::c_end(sequence), old_value,
622 new_value);
623}
624
625// c_replace_if()
626//
627// Container-based version of the <algorithm> `std::replace_if()` function to
628// replace a container's elements of some value with a new value based on some
629// condition. The container is modified in place.
630template <typename C, typename Pred, typename T>
631void c_replace_if(C& c, Pred&& pred, T&& new_value) {
632 std::replace_if(container_algorithm_internal::c_begin(c),
633 container_algorithm_internal::c_end(c),
634 std::forward<Pred>(pred), std::forward<T>(new_value));
635}
636
637// c_replace_copy()
638//
639// Container-based version of the <algorithm> `std::replace_copy()` function to
640// replace a container's elements of some value with a new value and return the
641// results within an iterator.
642template <typename C, typename OutputIterator, typename T>
643OutputIterator c_replace_copy(const C& c, OutputIterator result, T&& old_value,
644 T&& new_value) {
645 return std::replace_copy(container_algorithm_internal::c_begin(c),
646 container_algorithm_internal::c_end(c), result,
647 std::forward<T>(old_value),
648 std::forward<T>(new_value));
649}
650
651// c_replace_copy_if()
652//
653// Container-based version of the <algorithm> `std::replace_copy_if()` function
654// to replace a container's elements of some value with a new value based on
655// some condition, and return the results within an iterator.
656template <typename C, typename OutputIterator, typename Pred, typename T>
657OutputIterator c_replace_copy_if(const C& c, OutputIterator result, Pred&& pred,
658 T&& new_value) {
659 return std::replace_copy_if(container_algorithm_internal::c_begin(c),
660 container_algorithm_internal::c_end(c), result,
661 std::forward<Pred>(pred),
662 std::forward<T>(new_value));
663}
664
665// c_fill()
666//
667// Container-based version of the <algorithm> `std::fill()` function to fill a
668// container with some value.
669template <typename C, typename T>
670void c_fill(C& c, T&& value) {
671 std::fill(container_algorithm_internal::c_begin(c),
672 container_algorithm_internal::c_end(c), std::forward<T>(value));
673}
674
675// c_fill_n()
676//
677// Container-based version of the <algorithm> `std::fill_n()` function to fill
678// the first N elements in a container with some value.
679template <typename C, typename Size, typename T>
680void c_fill_n(C& c, Size n, T&& value) {
681 std::fill_n(container_algorithm_internal::c_begin(c), n,
682 std::forward<T>(value));
683}
684
685// c_generate()
686//
687// Container-based version of the <algorithm> `std::generate()` function to
688// assign a container's elements to the values provided by the given generator.
689template <typename C, typename Generator>
690void c_generate(C& c, Generator&& gen) {
691 std::generate(container_algorithm_internal::c_begin(c),
692 container_algorithm_internal::c_end(c),
693 std::forward<Generator>(gen));
694}
695
696// c_generate_n()
697//
698// Container-based version of the <algorithm> `std::generate_n()` function to
699// assign a container's first N elements to the values provided by the given
700// generator.
701template <typename C, typename Size, typename Generator>
702container_algorithm_internal::ContainerIter<C> c_generate_n(C& c, Size n,
703 Generator&& gen) {
704 return std::generate_n(container_algorithm_internal::c_begin(c), n,
705 std::forward<Generator>(gen));
706}
707
708// Note: `c_xx()` <algorithm> container versions for `remove()`, `remove_if()`,
709// and `unique()` are omitted, because it's not clear whether or not such
710// functions should call erase on their supplied sequences afterwards. Either
711// behavior would be surprising for a different set of users.
712
713// c_remove_copy()
714//
715// Container-based version of the <algorithm> `std::remove_copy()` function to
716// copy a container's elements while removing any elements matching the given
717// `value`.
718template <typename C, typename OutputIterator, typename T>
719OutputIterator c_remove_copy(const C& c, OutputIterator result, T&& value) {
720 return std::remove_copy(container_algorithm_internal::c_begin(c),
721 container_algorithm_internal::c_end(c), result,
722 std::forward<T>(value));
723}
724
725// c_remove_copy_if()
726//
727// Container-based version of the <algorithm> `std::remove_copy_if()` function
728// to copy a container's elements while removing any elements matching the given
729// condition.
730template <typename C, typename OutputIterator, typename Pred>
731OutputIterator c_remove_copy_if(const C& c, OutputIterator result,
732 Pred&& pred) {
733 return std::remove_copy_if(container_algorithm_internal::c_begin(c),
734 container_algorithm_internal::c_end(c), result,
735 std::forward<Pred>(pred));
736}
737
738// c_unique_copy()
739//
740// Container-based version of the <algorithm> `std::unique_copy()` function to
741// copy a container's elements while removing any elements containing duplicate
742// values.
743template <typename C, typename OutputIterator>
744OutputIterator c_unique_copy(const C& c, OutputIterator result) {
745 return std::unique_copy(container_algorithm_internal::c_begin(c),
746 container_algorithm_internal::c_end(c), result);
747}
748
749// Overload of c_unique_copy() for using a predicate evaluation other than
750// `==` for comparing uniqueness of the element values.
751template <typename C, typename OutputIterator, typename BinaryPredicate>
752OutputIterator c_unique_copy(const C& c, OutputIterator result,
753 BinaryPredicate&& pred) {
754 return std::unique_copy(container_algorithm_internal::c_begin(c),
755 container_algorithm_internal::c_end(c), result,
756 std::forward<BinaryPredicate>(pred));
757}
758
759// c_reverse()
760//
761// Container-based version of the <algorithm> `std::reverse()` function to
762// reverse a container's elements.
763template <typename Sequence>
764void c_reverse(Sequence& sequence) {
765 std::reverse(container_algorithm_internal::c_begin(sequence),
766 container_algorithm_internal::c_end(sequence));
767}
768
769// c_reverse_copy()
770//
771// Container-based version of the <algorithm> `std::reverse()` function to
772// reverse a container's elements and write them to an iterator range.
773template <typename C, typename OutputIterator>
774OutputIterator c_reverse_copy(const C& sequence, OutputIterator result) {
775 return std::reverse_copy(container_algorithm_internal::c_begin(sequence),
776 container_algorithm_internal::c_end(sequence),
777 result);
778}
779
780// c_rotate()
781//
782// Container-based version of the <algorithm> `std::rotate()` function to
783// shift a container's elements leftward such that the `middle` element becomes
784// the first element in the container.
785template <typename C,
786 typename Iterator = container_algorithm_internal::ContainerIter<C>>
787Iterator c_rotate(C& sequence, Iterator middle) {
788 return absl::rotate(container_algorithm_internal::c_begin(sequence), middle,
789 container_algorithm_internal::c_end(sequence));
790}
791
792// c_rotate_copy()
793//
794// Container-based version of the <algorithm> `std::rotate_copy()` function to
795// shift a container's elements leftward such that the `middle` element becomes
796// the first element in a new iterator range.
797template <typename C, typename OutputIterator>
798OutputIterator c_rotate_copy(
799 const C& sequence,
800 container_algorithm_internal::ContainerIter<const C> middle,
801 OutputIterator result) {
802 return std::rotate_copy(container_algorithm_internal::c_begin(sequence),
803 middle, container_algorithm_internal::c_end(sequence),
804 result);
805}
806
807// c_shuffle()
808//
809// Container-based version of the <algorithm> `std::shuffle()` function to
810// randomly shuffle elements within the container using a `gen()` uniform random
811// number generator.
812template <typename RandomAccessContainer, typename UniformRandomBitGenerator>
813void c_shuffle(RandomAccessContainer& c, UniformRandomBitGenerator&& gen) {
814 std::shuffle(container_algorithm_internal::c_begin(c),
815 container_algorithm_internal::c_end(c),
816 std::forward<UniformRandomBitGenerator>(gen));
817}
818
819//------------------------------------------------------------------------------
820// <algorithm> Partition functions
821//------------------------------------------------------------------------------
822
823// c_is_partitioned()
824//
825// Container-based version of the <algorithm> `std::is_partitioned()` function
826// to test whether all elements in the container for which `pred` returns `true`
827// precede those for which `pred` is `false`.
828template <typename C, typename Pred>
829bool c_is_partitioned(const C& c, Pred&& pred) {
830 return std::is_partitioned(container_algorithm_internal::c_begin(c),
831 container_algorithm_internal::c_end(c),
832 std::forward<Pred>(pred));
833}
834
835// c_partition()
836//
837// Container-based version of the <algorithm> `std::partition()` function
838// to rearrange all elements in a container in such a way that all elements for
839// which `pred` returns `true` precede all those for which it returns `false`,
840// returning an iterator to the first element of the second group.
841template <typename C, typename Pred>
842container_algorithm_internal::ContainerIter<C> c_partition(C& c, Pred&& pred) {
843 return std::partition(container_algorithm_internal::c_begin(c),
844 container_algorithm_internal::c_end(c),
845 std::forward<Pred>(pred));
846}
847
848// c_stable_partition()
849//
850// Container-based version of the <algorithm> `std::stable_partition()` function
851// to rearrange all elements in a container in such a way that all elements for
852// which `pred` returns `true` precede all those for which it returns `false`,
853// preserving the relative ordering between the two groups. The function returns
854// an iterator to the first element of the second group.
855template <typename C, typename Pred>
856container_algorithm_internal::ContainerIter<C> c_stable_partition(C& c,
857 Pred&& pred) {
858 return std::stable_partition(container_algorithm_internal::c_begin(c),
859 container_algorithm_internal::c_end(c),
860 std::forward<Pred>(pred));
861}
862
863// c_partition_copy()
864//
865// Container-based version of the <algorithm> `std::partition_copy()` function
866// to partition a container's elements and return them into two iterators: one
867// for which `pred` returns `true`, and one for which `pred` returns `false.`
868
869template <typename C, typename OutputIterator1, typename OutputIterator2,
870 typename Pred>
871std::pair<OutputIterator1, OutputIterator2> c_partition_copy(
872 const C& c, OutputIterator1 out_true, OutputIterator2 out_false,
873 Pred&& pred) {
874 return std::partition_copy(container_algorithm_internal::c_begin(c),
875 container_algorithm_internal::c_end(c), out_true,
876 out_false, std::forward<Pred>(pred));
877}
878
879// c_partition_point()
880//
881// Container-based version of the <algorithm> `std::partition_point()` function
882// to return the first element of an already partitioned container for which
883// the given `pred` is not `true`.
884template <typename C, typename Pred>
885container_algorithm_internal::ContainerIter<C> c_partition_point(C& c,
886 Pred&& pred) {
887 return std::partition_point(container_algorithm_internal::c_begin(c),
888 container_algorithm_internal::c_end(c),
889 std::forward<Pred>(pred));
890}
891
892//------------------------------------------------------------------------------
893// <algorithm> Sorting functions
894//------------------------------------------------------------------------------
895
896// c_sort()
897//
898// Container-based version of the <algorithm> `std::sort()` function
899// to sort elements in ascending order of their values.
900template <typename C>
901void c_sort(C& c) {
902 std::sort(container_algorithm_internal::c_begin(c),
903 container_algorithm_internal::c_end(c));
904}
905
906// Overload of c_sort() for performing a `comp` comparison other than the
907// default `operator<`.
908template <typename C, typename LessThan>
909void c_sort(C& c, LessThan&& comp) {
910 std::sort(container_algorithm_internal::c_begin(c),
911 container_algorithm_internal::c_end(c),
912 std::forward<LessThan>(comp));
913}
914
915// c_stable_sort()
916//
917// Container-based version of the <algorithm> `std::stable_sort()` function
918// to sort elements in ascending order of their values, preserving the order
919// of equivalents.
920template <typename C>
921void c_stable_sort(C& c) {
922 std::stable_sort(container_algorithm_internal::c_begin(c),
923 container_algorithm_internal::c_end(c));
924}
925
926// Overload of c_stable_sort() for performing a `comp` comparison other than the
927// default `operator<`.
928template <typename C, typename LessThan>
929void c_stable_sort(C& c, LessThan&& comp) {
930 std::stable_sort(container_algorithm_internal::c_begin(c),
931 container_algorithm_internal::c_end(c),
932 std::forward<LessThan>(comp));
933}
934
935// c_is_sorted()
936//
937// Container-based version of the <algorithm> `std::is_sorted()` function
938// to evaluate whether the given container is sorted in ascending order.
939template <typename C>
940bool c_is_sorted(const C& c) {
941 return std::is_sorted(container_algorithm_internal::c_begin(c),
942 container_algorithm_internal::c_end(c));
943}
944
945// c_is_sorted() overload for performing a `comp` comparison other than the
946// default `operator<`.
947template <typename C, typename LessThan>
948bool c_is_sorted(const C& c, LessThan&& comp) {
949 return std::is_sorted(container_algorithm_internal::c_begin(c),
950 container_algorithm_internal::c_end(c),
951 std::forward<LessThan>(comp));
952}
953
954// c_partial_sort()
955//
956// Container-based version of the <algorithm> `std::partial_sort()` function
957// to rearrange elements within a container such that elements before `middle`
958// are sorted in ascending order.
959template <typename RandomAccessContainer>
960void c_partial_sort(
961 RandomAccessContainer& sequence,
962 container_algorithm_internal::ContainerIter<RandomAccessContainer> middle) {
963 std::partial_sort(container_algorithm_internal::c_begin(sequence), middle,
964 container_algorithm_internal::c_end(sequence));
965}
966
967// Overload of c_partial_sort() for performing a `comp` comparison other than
968// the default `operator<`.
969template <typename RandomAccessContainer, typename LessThan>
970void c_partial_sort(
971 RandomAccessContainer& sequence,
972 container_algorithm_internal::ContainerIter<RandomAccessContainer> middle,
973 LessThan&& comp) {
974 std::partial_sort(container_algorithm_internal::c_begin(sequence), middle,
975 container_algorithm_internal::c_end(sequence),
976 std::forward<LessThan>(comp));
977}
978
979// c_partial_sort_copy()
980//
981// Container-based version of the <algorithm> `std::partial_sort_copy()`
982// function to sort the elements in the given range `result` within the larger
983// `sequence` in ascending order (and using `result` as the output parameter).
984// At most min(result.last - result.first, sequence.last - sequence.first)
985// elements from the sequence will be stored in the result.
986template <typename C, typename RandomAccessContainer>
987container_algorithm_internal::ContainerIter<RandomAccessContainer>
988c_partial_sort_copy(const C& sequence, RandomAccessContainer& result) {
989 return std::partial_sort_copy(container_algorithm_internal::c_begin(sequence),
990 container_algorithm_internal::c_end(sequence),
991 container_algorithm_internal::c_begin(result),
992 container_algorithm_internal::c_end(result));
993}
994
995// Overload of c_partial_sort_copy() for performing a `comp` comparison other
996// than the default `operator<`.
997template <typename C, typename RandomAccessContainer, typename LessThan>
998container_algorithm_internal::ContainerIter<RandomAccessContainer>
999c_partial_sort_copy(const C& sequence, RandomAccessContainer& result,
1000 LessThan&& comp) {
1001 return std::partial_sort_copy(container_algorithm_internal::c_begin(sequence),
1002 container_algorithm_internal::c_end(sequence),
1003 container_algorithm_internal::c_begin(result),
1004 container_algorithm_internal::c_end(result),
1005 std::forward<LessThan>(comp));
1006}
1007
1008// c_is_sorted_until()
1009//
1010// Container-based version of the <algorithm> `std::is_sorted_until()` function
1011// to return the first element within a container that is not sorted in
1012// ascending order as an iterator.
1013template <typename C>
1014container_algorithm_internal::ContainerIter<C> c_is_sorted_until(C& c) {
1015 return std::is_sorted_until(container_algorithm_internal::c_begin(c),
1016 container_algorithm_internal::c_end(c));
1017}
1018
1019// Overload of c_is_sorted_until() for performing a `comp` comparison other than
1020// the default `operator<`.
1021template <typename C, typename LessThan>
1022container_algorithm_internal::ContainerIter<C> c_is_sorted_until(
1023 C& c, LessThan&& comp) {
1024 return std::is_sorted_until(container_algorithm_internal::c_begin(c),
1025 container_algorithm_internal::c_end(c),
1026 std::forward<LessThan>(comp));
1027}
1028
1029// c_nth_element()
1030//
1031// Container-based version of the <algorithm> `std::nth_element()` function
1032// to rearrange the elements within a container such that the `nth` element
1033// would be in that position in an ordered sequence; other elements may be in
1034// any order, except that all preceding `nth` will be less than that element,
1035// and all following `nth` will be greater than that element.
1036template <typename RandomAccessContainer>
1037void c_nth_element(
1038 RandomAccessContainer& sequence,
1039 container_algorithm_internal::ContainerIter<RandomAccessContainer> nth) {
1040 std::nth_element(container_algorithm_internal::c_begin(sequence), nth,
1041 container_algorithm_internal::c_end(sequence));
1042}
1043
1044// Overload of c_nth_element() for performing a `comp` comparison other than
1045// the default `operator<`.
1046template <typename RandomAccessContainer, typename LessThan>
1047void c_nth_element(
1048 RandomAccessContainer& sequence,
1049 container_algorithm_internal::ContainerIter<RandomAccessContainer> nth,
1050 LessThan&& comp) {
1051 std::nth_element(container_algorithm_internal::c_begin(sequence), nth,
1052 container_algorithm_internal::c_end(sequence),
1053 std::forward<LessThan>(comp));
1054}
1055
1056//------------------------------------------------------------------------------
1057// <algorithm> Binary Search
1058//------------------------------------------------------------------------------
1059
1060// c_lower_bound()
1061//
1062// Container-based version of the <algorithm> `std::lower_bound()` function
1063// to return an iterator pointing to the first element in a sorted container
1064// which does not compare less than `value`.
1065template <typename Sequence, typename T>
1066container_algorithm_internal::ContainerIter<Sequence> c_lower_bound(
1067 Sequence& sequence, T&& value) {
1068 return std::lower_bound(container_algorithm_internal::c_begin(sequence),
1069 container_algorithm_internal::c_end(sequence),
1070 std::forward<T>(value));
1071}
1072
1073// Overload of c_lower_bound() for performing a `comp` comparison other than
1074// the default `operator<`.
1075template <typename Sequence, typename T, typename LessThan>
1076container_algorithm_internal::ContainerIter<Sequence> c_lower_bound(
1077 Sequence& sequence, T&& value, LessThan&& comp) {
1078 return std::lower_bound(container_algorithm_internal::c_begin(sequence),
1079 container_algorithm_internal::c_end(sequence),
1080 std::forward<T>(value), std::forward<LessThan>(comp));
1081}
1082
1083// c_upper_bound()
1084//
1085// Container-based version of the <algorithm> `std::upper_bound()` function
1086// to return an iterator pointing to the first element in a sorted container
1087// which is greater than `value`.
1088template <typename Sequence, typename T>
1089container_algorithm_internal::ContainerIter<Sequence> c_upper_bound(
1090 Sequence& sequence, T&& value) {
1091 return std::upper_bound(container_algorithm_internal::c_begin(sequence),
1092 container_algorithm_internal::c_end(sequence),
1093 std::forward<T>(value));
1094}
1095
1096// Overload of c_upper_bound() for performing a `comp` comparison other than
1097// the default `operator<`.
1098template <typename Sequence, typename T, typename LessThan>
1099container_algorithm_internal::ContainerIter<Sequence> c_upper_bound(
1100 Sequence& sequence, T&& value, LessThan&& comp) {
1101 return std::upper_bound(container_algorithm_internal::c_begin(sequence),
1102 container_algorithm_internal::c_end(sequence),
1103 std::forward<T>(value), std::forward<LessThan>(comp));
1104}
1105
1106// c_equal_range()
1107//
1108// Container-based version of the <algorithm> `std::equal_range()` function
1109// to return an iterator pair pointing to the first and last elements in a
1110// sorted container which compare equal to `value`.
1111template <typename Sequence, typename T>
1112container_algorithm_internal::ContainerIterPairType<Sequence, Sequence>
1113c_equal_range(Sequence& sequence, T&& value) {
1114 return std::equal_range(container_algorithm_internal::c_begin(sequence),
1115 container_algorithm_internal::c_end(sequence),
1116 std::forward<T>(value));
1117}
1118
1119// Overload of c_equal_range() for performing a `comp` comparison other than
1120// the default `operator<`.
1121template <typename Sequence, typename T, typename LessThan>
1122container_algorithm_internal::ContainerIterPairType<Sequence, Sequence>
1123c_equal_range(Sequence& sequence, T&& value, LessThan&& comp) {
1124 return std::equal_range(container_algorithm_internal::c_begin(sequence),
1125 container_algorithm_internal::c_end(sequence),
1126 std::forward<T>(value), std::forward<LessThan>(comp));
1127}
1128
1129// c_binary_search()
1130//
1131// Container-based version of the <algorithm> `std::binary_search()` function
1132// to test if any element in the sorted container contains a value equivalent to
1133// 'value'.
1134template <typename Sequence, typename T>
1135bool c_binary_search(Sequence&& sequence, T&& value) {
1136 return std::binary_search(container_algorithm_internal::c_begin(sequence),
1137 container_algorithm_internal::c_end(sequence),
1138 std::forward<T>(value));
1139}
1140
1141// Overload of c_binary_search() for performing a `comp` comparison other than
1142// the default `operator<`.
1143template <typename Sequence, typename T, typename LessThan>
1144bool c_binary_search(Sequence&& sequence, T&& value, LessThan&& comp) {
1145 return std::binary_search(container_algorithm_internal::c_begin(sequence),
1146 container_algorithm_internal::c_end(sequence),
1147 std::forward<T>(value),
1148 std::forward<LessThan>(comp));
1149}
1150
1151//------------------------------------------------------------------------------
1152// <algorithm> Merge functions
1153//------------------------------------------------------------------------------
1154
1155// c_merge()
1156//
1157// Container-based version of the <algorithm> `std::merge()` function
1158// to merge two sorted containers into a single sorted iterator.
1159template <typename C1, typename C2, typename OutputIterator>
1160OutputIterator c_merge(const C1& c1, const C2& c2, OutputIterator result) {
1161 return std::merge(container_algorithm_internal::c_begin(c1),
1162 container_algorithm_internal::c_end(c1),
1163 container_algorithm_internal::c_begin(c2),
1164 container_algorithm_internal::c_end(c2), result);
1165}
1166
1167// Overload of c_merge() for performing a `comp` comparison other than
1168// the default `operator<`.
1169template <typename C1, typename C2, typename OutputIterator, typename LessThan>
1170OutputIterator c_merge(const C1& c1, const C2& c2, OutputIterator result,
1171 LessThan&& comp) {
1172 return std::merge(container_algorithm_internal::c_begin(c1),
1173 container_algorithm_internal::c_end(c1),
1174 container_algorithm_internal::c_begin(c2),
1175 container_algorithm_internal::c_end(c2), result,
1176 std::forward<LessThan>(comp));
1177}
1178
1179// c_inplace_merge()
1180//
1181// Container-based version of the <algorithm> `std::inplace_merge()` function
1182// to merge a supplied iterator `middle` into a container.
1183template <typename C>
1184void c_inplace_merge(C& c,
1185 container_algorithm_internal::ContainerIter<C> middle) {
1186 std::inplace_merge(container_algorithm_internal::c_begin(c), middle,
1187 container_algorithm_internal::c_end(c));
1188}
1189
1190// Overload of c_inplace_merge() for performing a merge using a `comp` other
1191// than `operator<`.
1192template <typename C, typename LessThan>
1193void c_inplace_merge(C& c,
1194 container_algorithm_internal::ContainerIter<C> middle,
1195 LessThan&& comp) {
1196 std::inplace_merge(container_algorithm_internal::c_begin(c), middle,
1197 container_algorithm_internal::c_end(c),
1198 std::forward<LessThan>(comp));
1199}
1200
1201// c_includes()
1202//
1203// Container-based version of the <algorithm> `std::includes()` function
1204// to test whether a sorted container `c1` entirely contains another sorted
1205// container `c2`.
1206template <typename C1, typename C2>
1207bool c_includes(const C1& c1, const C2& c2) {
1208 return std::includes(container_algorithm_internal::c_begin(c1),
1209 container_algorithm_internal::c_end(c1),
1210 container_algorithm_internal::c_begin(c2),
1211 container_algorithm_internal::c_end(c2));
1212}
1213
1214// Overload of c_includes() for performing a merge using a `comp` other than
1215// `operator<`.
1216template <typename C1, typename C2, typename LessThan>
1217bool c_includes(const C1& c1, const C2& c2, LessThan&& comp) {
1218 return std::includes(container_algorithm_internal::c_begin(c1),
1219 container_algorithm_internal::c_end(c1),
1220 container_algorithm_internal::c_begin(c2),
1221 container_algorithm_internal::c_end(c2),
1222 std::forward<LessThan>(comp));
1223}
1224
1225// c_set_union()
1226//
1227// Container-based version of the <algorithm> `std::set_union()` function
1228// to return an iterator containing the union of two containers; duplicate
1229// values are not copied into the output.
1230template <typename C1, typename C2, typename OutputIterator,
1231 typename = typename std::enable_if<
1232 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1233 void>::type,
1234 typename = typename std::enable_if<
1235 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1236 void>::type>
1237OutputIterator c_set_union(const C1& c1, const C2& c2, OutputIterator output) {
1238 return std::set_union(container_algorithm_internal::c_begin(c1),
1239 container_algorithm_internal::c_end(c1),
1240 container_algorithm_internal::c_begin(c2),
1241 container_algorithm_internal::c_end(c2), output);
1242}
1243
1244// Overload of c_set_union() for performing a merge using a `comp` other than
1245// `operator<`.
1246template <typename C1, typename C2, typename OutputIterator, typename LessThan,
1247 typename = typename std::enable_if<
1248 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1249 void>::type,
1250 typename = typename std::enable_if<
1251 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1252 void>::type>
1253OutputIterator c_set_union(const C1& c1, const C2& c2, OutputIterator output,
1254 LessThan&& comp) {
1255 return std::set_union(container_algorithm_internal::c_begin(c1),
1256 container_algorithm_internal::c_end(c1),
1257 container_algorithm_internal::c_begin(c2),
1258 container_algorithm_internal::c_end(c2), output,
1259 std::forward<LessThan>(comp));
1260}
1261
1262// c_set_intersection()
1263//
1264// Container-based version of the <algorithm> `std::set_intersection()` function
1265// to return an iterator containing the intersection of two sorted containers.
1266template <typename C1, typename C2, typename OutputIterator,
1267 typename = typename std::enable_if<
1268 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1269 void>::type,
1270 typename = typename std::enable_if<
1271 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1272 void>::type>
1273OutputIterator c_set_intersection(const C1& c1, const C2& c2,
1274 OutputIterator output) {
1275 // In debug builds, ensure that both containers are sorted with respect to the
1276 // default comparator. std::set_intersection requires the containers be sorted
1277 // using operator<.
1278 assert(absl::c_is_sorted(c1));
1279 assert(absl::c_is_sorted(c2));
1280 return std::set_intersection(container_algorithm_internal::c_begin(c1),
1281 container_algorithm_internal::c_end(c1),
1282 container_algorithm_internal::c_begin(c2),
1283 container_algorithm_internal::c_end(c2), output);
1284}
1285
1286// Overload of c_set_intersection() for performing a merge using a `comp` other
1287// than `operator<`.
1288template <typename C1, typename C2, typename OutputIterator, typename LessThan,
1289 typename = typename std::enable_if<
1290 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1291 void>::type,
1292 typename = typename std::enable_if<
1293 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1294 void>::type>
1295OutputIterator c_set_intersection(const C1& c1, const C2& c2,
1296 OutputIterator output, LessThan&& comp) {
1297 // In debug builds, ensure that both containers are sorted with respect to the
1298 // default comparator. std::set_intersection requires the containers be sorted
1299 // using the same comparator.
1300 assert(absl::c_is_sorted(c1, comp));
1301 assert(absl::c_is_sorted(c2, comp));
1302 return std::set_intersection(container_algorithm_internal::c_begin(c1),
1303 container_algorithm_internal::c_end(c1),
1304 container_algorithm_internal::c_begin(c2),
1305 container_algorithm_internal::c_end(c2), output,
1306 std::forward<LessThan>(comp));
1307}
1308
1309// c_set_difference()
1310//
1311// Container-based version of the <algorithm> `std::set_difference()` function
1312// to return an iterator containing elements present in the first container but
1313// not in the second.
1314template <typename C1, typename C2, typename OutputIterator,
1315 typename = typename std::enable_if<
1316 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1317 void>::type,
1318 typename = typename std::enable_if<
1319 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1320 void>::type>
1321OutputIterator c_set_difference(const C1& c1, const C2& c2,
1322 OutputIterator output) {
1323 return std::set_difference(container_algorithm_internal::c_begin(c1),
1324 container_algorithm_internal::c_end(c1),
1325 container_algorithm_internal::c_begin(c2),
1326 container_algorithm_internal::c_end(c2), output);
1327}
1328
1329// Overload of c_set_difference() for performing a merge using a `comp` other
1330// than `operator<`.
1331template <typename C1, typename C2, typename OutputIterator, typename LessThan,
1332 typename = typename std::enable_if<
1333 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1334 void>::type,
1335 typename = typename std::enable_if<
1336 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1337 void>::type>
1338OutputIterator c_set_difference(const C1& c1, const C2& c2,
1339 OutputIterator output, LessThan&& comp) {
1340 return std::set_difference(container_algorithm_internal::c_begin(c1),
1341 container_algorithm_internal::c_end(c1),
1342 container_algorithm_internal::c_begin(c2),
1343 container_algorithm_internal::c_end(c2), output,
1344 std::forward<LessThan>(comp));
1345}
1346
1347// c_set_symmetric_difference()
1348//
1349// Container-based version of the <algorithm> `std::set_symmetric_difference()`
1350// function to return an iterator containing elements present in either one
1351// container or the other, but not both.
1352template <typename C1, typename C2, typename OutputIterator,
1353 typename = typename std::enable_if<
1354 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1355 void>::type,
1356 typename = typename std::enable_if<
1357 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1358 void>::type>
1359OutputIterator c_set_symmetric_difference(const C1& c1, const C2& c2,
1360 OutputIterator output) {
1361 return std::set_symmetric_difference(
1362 container_algorithm_internal::c_begin(c1),
1363 container_algorithm_internal::c_end(c1),
1364 container_algorithm_internal::c_begin(c2),
1365 container_algorithm_internal::c_end(c2), output);
1366}
1367
1368// Overload of c_set_symmetric_difference() for performing a merge using a
1369// `comp` other than `operator<`.
1370template <typename C1, typename C2, typename OutputIterator, typename LessThan,
1371 typename = typename std::enable_if<
1372 !container_algorithm_internal::IsUnorderedContainer<C1>::value,
1373 void>::type,
1374 typename = typename std::enable_if<
1375 !container_algorithm_internal::IsUnorderedContainer<C2>::value,
1376 void>::type>
1377OutputIterator c_set_symmetric_difference(const C1& c1, const C2& c2,
1378 OutputIterator output,
1379 LessThan&& comp) {
1380 return std::set_symmetric_difference(
1381 container_algorithm_internal::c_begin(c1),
1382 container_algorithm_internal::c_end(c1),
1383 container_algorithm_internal::c_begin(c2),
1384 container_algorithm_internal::c_end(c2), output,
1385 std::forward<LessThan>(comp));
1386}
1387
1388//------------------------------------------------------------------------------
1389// <algorithm> Heap functions
1390//------------------------------------------------------------------------------
1391
1392// c_push_heap()
1393//
1394// Container-based version of the <algorithm> `std::push_heap()` function
1395// to push a value onto a container heap.
1396template <typename RandomAccessContainer>
1397void c_push_heap(RandomAccessContainer& sequence) {
1398 std::push_heap(container_algorithm_internal::c_begin(sequence),
1399 container_algorithm_internal::c_end(sequence));
1400}
1401
1402// Overload of c_push_heap() for performing a push operation on a heap using a
1403// `comp` other than `operator<`.
1404template <typename RandomAccessContainer, typename LessThan>
1405void c_push_heap(RandomAccessContainer& sequence, LessThan&& comp) {
1406 std::push_heap(container_algorithm_internal::c_begin(sequence),
1407 container_algorithm_internal::c_end(sequence),
1408 std::forward<LessThan>(comp));
1409}
1410
1411// c_pop_heap()
1412//
1413// Container-based version of the <algorithm> `std::pop_heap()` function
1414// to pop a value from a heap container.
1415template <typename RandomAccessContainer>
1416void c_pop_heap(RandomAccessContainer& sequence) {
1417 std::pop_heap(container_algorithm_internal::c_begin(sequence),
1418 container_algorithm_internal::c_end(sequence));
1419}
1420
1421// Overload of c_pop_heap() for performing a pop operation on a heap using a
1422// `comp` other than `operator<`.
1423template <typename RandomAccessContainer, typename LessThan>
1424void c_pop_heap(RandomAccessContainer& sequence, LessThan&& comp) {
1425 std::pop_heap(container_algorithm_internal::c_begin(sequence),
1426 container_algorithm_internal::c_end(sequence),
1427 std::forward<LessThan>(comp));
1428}
1429
1430// c_make_heap()
1431//
1432// Container-based version of the <algorithm> `std::make_heap()` function
1433// to make a container a heap.
1434template <typename RandomAccessContainer>
1435void c_make_heap(RandomAccessContainer& sequence) {
1436 std::make_heap(container_algorithm_internal::c_begin(sequence),
1437 container_algorithm_internal::c_end(sequence));
1438}
1439
1440// Overload of c_make_heap() for performing heap comparisons using a
1441// `comp` other than `operator<`
1442template <typename RandomAccessContainer, typename LessThan>
1443void c_make_heap(RandomAccessContainer& sequence, LessThan&& comp) {
1444 std::make_heap(container_algorithm_internal::c_begin(sequence),
1445 container_algorithm_internal::c_end(sequence),
1446 std::forward<LessThan>(comp));
1447}
1448
1449// c_sort_heap()
1450//
1451// Container-based version of the <algorithm> `std::sort_heap()` function
1452// to sort a heap into ascending order (after which it is no longer a heap).
1453template <typename RandomAccessContainer>
1454void c_sort_heap(RandomAccessContainer& sequence) {
1455 std::sort_heap(container_algorithm_internal::c_begin(sequence),
1456 container_algorithm_internal::c_end(sequence));
1457}
1458
1459// Overload of c_sort_heap() for performing heap comparisons using a
1460// `comp` other than `operator<`
1461template <typename RandomAccessContainer, typename LessThan>
1462void c_sort_heap(RandomAccessContainer& sequence, LessThan&& comp) {
1463 std::sort_heap(container_algorithm_internal::c_begin(sequence),
1464 container_algorithm_internal::c_end(sequence),
1465 std::forward<LessThan>(comp));
1466}
1467
1468// c_is_heap()
1469//
1470// Container-based version of the <algorithm> `std::is_heap()` function
1471// to check whether the given container is a heap.
1472template <typename RandomAccessContainer>
1473bool c_is_heap(const RandomAccessContainer& sequence) {
1474 return std::is_heap(container_algorithm_internal::c_begin(sequence),
1475 container_algorithm_internal::c_end(sequence));
1476}
1477
1478// Overload of c_is_heap() for performing heap comparisons using a
1479// `comp` other than `operator<`
1480template <typename RandomAccessContainer, typename LessThan>
1481bool c_is_heap(const RandomAccessContainer& sequence, LessThan&& comp) {
1482 return std::is_heap(container_algorithm_internal::c_begin(sequence),
1483 container_algorithm_internal::c_end(sequence),
1484 std::forward<LessThan>(comp));
1485}
1486
1487// c_is_heap_until()
1488//
1489// Container-based version of the <algorithm> `std::is_heap_until()` function
1490// to find the first element in a given container which is not in heap order.
1491template <typename RandomAccessContainer>
1492container_algorithm_internal::ContainerIter<RandomAccessContainer>
1493c_is_heap_until(RandomAccessContainer& sequence) {
1494 return std::is_heap_until(container_algorithm_internal::c_begin(sequence),
1495 container_algorithm_internal::c_end(sequence));
1496}
1497
1498// Overload of c_is_heap_until() for performing heap comparisons using a
1499// `comp` other than `operator<`
1500template <typename RandomAccessContainer, typename LessThan>
1501container_algorithm_internal::ContainerIter<RandomAccessContainer>
1502c_is_heap_until(RandomAccessContainer& sequence, LessThan&& comp) {
1503 return std::is_heap_until(container_algorithm_internal::c_begin(sequence),
1504 container_algorithm_internal::c_end(sequence),
1505 std::forward<LessThan>(comp));
1506}
1507
1508//------------------------------------------------------------------------------
1509// <algorithm> Min/max
1510//------------------------------------------------------------------------------
1511
1512// c_min_element()
1513//
1514// Container-based version of the <algorithm> `std::min_element()` function
1515// to return an iterator pointing to the element with the smallest value, using
1516// `operator<` to make the comparisons.
1517template <typename Sequence>
1518container_algorithm_internal::ContainerIter<Sequence> c_min_element(
1519 Sequence& sequence) {
1520 return std::min_element(container_algorithm_internal::c_begin(sequence),
1521 container_algorithm_internal::c_end(sequence));
1522}
1523
1524// Overload of c_min_element() for performing a `comp` comparison other than
1525// `operator<`.
1526template <typename Sequence, typename LessThan>
1527container_algorithm_internal::ContainerIter<Sequence> c_min_element(
1528 Sequence& sequence, LessThan&& comp) {
1529 return std::min_element(container_algorithm_internal::c_begin(sequence),
1530 container_algorithm_internal::c_end(sequence),
1531 std::forward<LessThan>(comp));
1532}
1533
1534// c_max_element()
1535//
1536// Container-based version of the <algorithm> `std::max_element()` function
1537// to return an iterator pointing to the element with the largest value, using
1538// `operator<` to make the comparisons.
1539template <typename Sequence>
1540container_algorithm_internal::ContainerIter<Sequence> c_max_element(
1541 Sequence& sequence) {
1542 return std::max_element(container_algorithm_internal::c_begin(sequence),
1543 container_algorithm_internal::c_end(sequence));
1544}
1545
1546// Overload of c_max_element() for performing a `comp` comparison other than
1547// `operator<`.
1548template <typename Sequence, typename LessThan>
1549container_algorithm_internal::ContainerIter<Sequence> c_max_element(
1550 Sequence& sequence, LessThan&& comp) {
1551 return std::max_element(container_algorithm_internal::c_begin(sequence),
1552 container_algorithm_internal::c_end(sequence),
1553 std::forward<LessThan>(comp));
1554}
1555
1556// c_minmax_element()
1557//
1558// Container-based version of the <algorithm> `std::minmax_element()` function
1559// to return a pair of iterators pointing to the elements containing the
1560// smallest and largest values, respectively, using `operator<` to make the
1561// comparisons.
1562template <typename C>
1563container_algorithm_internal::ContainerIterPairType<C, C>
1564c_minmax_element(C& c) {
1565 return std::minmax_element(container_algorithm_internal::c_begin(c),
1566 container_algorithm_internal::c_end(c));
1567}
1568
1569// Overload of c_minmax_element() for performing `comp` comparisons other than
1570// `operator<`.
1571template <typename C, typename LessThan>
1572container_algorithm_internal::ContainerIterPairType<C, C>
1573c_minmax_element(C& c, LessThan&& comp) {
1574 return std::minmax_element(container_algorithm_internal::c_begin(c),
1575 container_algorithm_internal::c_end(c),
1576 std::forward<LessThan>(comp));
1577}
1578
1579//------------------------------------------------------------------------------
1580// <algorithm> Lexicographical Comparisons
1581//------------------------------------------------------------------------------
1582
1583// c_lexicographical_compare()
1584//
1585// Container-based version of the <algorithm> `std::lexicographical_compare()`
1586// function to lexicographically compare (e.g. sort words alphabetically) two
1587// container sequences. The comparison is performed using `operator<`. Note
1588// that capital letters ("A-Z") have ASCII values less than lowercase letters
1589// ("a-z").
1590template <typename Sequence1, typename Sequence2>
1591bool c_lexicographical_compare(Sequence1&& sequence1, Sequence2&& sequence2) {
1592 return std::lexicographical_compare(
1593 container_algorithm_internal::c_begin(sequence1),
1594 container_algorithm_internal::c_end(sequence1),
1595 container_algorithm_internal::c_begin(sequence2),
1596 container_algorithm_internal::c_end(sequence2));
1597}
1598
1599// Overload of c_lexicographical_compare() for performing a lexicographical
1600// comparison using a `comp` operator instead of `operator<`.
1601template <typename Sequence1, typename Sequence2, typename LessThan>
1602bool c_lexicographical_compare(Sequence1&& sequence1, Sequence2&& sequence2,
1603 LessThan&& comp) {
1604 return std::lexicographical_compare(
1605 container_algorithm_internal::c_begin(sequence1),
1606 container_algorithm_internal::c_end(sequence1),
1607 container_algorithm_internal::c_begin(sequence2),
1608 container_algorithm_internal::c_end(sequence2),
1609 std::forward<LessThan>(comp));
1610}
1611
1612// c_next_permutation()
1613//
1614// Container-based version of the <algorithm> `std::next_permutation()` function
1615// to rearrange a container's elements into the next lexicographically greater
1616// permutation.
1617template <typename C>
1618bool c_next_permutation(C& c) {
1619 return std::next_permutation(container_algorithm_internal::c_begin(c),
1620 container_algorithm_internal::c_end(c));
1621}
1622
1623// Overload of c_next_permutation() for performing a lexicographical
1624// comparison using a `comp` operator instead of `operator<`.
1625template <typename C, typename LessThan>
1626bool c_next_permutation(C& c, LessThan&& comp) {
1627 return std::next_permutation(container_algorithm_internal::c_begin(c),
1628 container_algorithm_internal::c_end(c),
1629 std::forward<LessThan>(comp));
1630}
1631
1632// c_prev_permutation()
1633//
1634// Container-based version of the <algorithm> `std::prev_permutation()` function
1635// to rearrange a container's elements into the next lexicographically lesser
1636// permutation.
1637template <typename C>
1638bool c_prev_permutation(C& c) {
1639 return std::prev_permutation(container_algorithm_internal::c_begin(c),
1640 container_algorithm_internal::c_end(c));
1641}
1642
1643// Overload of c_prev_permutation() for performing a lexicographical
1644// comparison using a `comp` operator instead of `operator<`.
1645template <typename C, typename LessThan>
1646bool c_prev_permutation(C& c, LessThan&& comp) {
1647 return std::prev_permutation(container_algorithm_internal::c_begin(c),
1648 container_algorithm_internal::c_end(c),
1649 std::forward<LessThan>(comp));
1650}
1651
1652//------------------------------------------------------------------------------
1653// <numeric> algorithms
1654//------------------------------------------------------------------------------
1655
1656// c_iota()
1657//
1658// Container-based version of the <algorithm> `std::iota()` function
1659// to compute successive values of `value`, as if incremented with `++value`
1660// after each element is written. and write them to the container.
1661template <typename Sequence, typename T>
1662void c_iota(Sequence& sequence, T&& value) {
1663 std::iota(container_algorithm_internal::c_begin(sequence),
1664 container_algorithm_internal::c_end(sequence),
1665 std::forward<T>(value));
1666}
1667// c_accumulate()
1668//
1669// Container-based version of the <algorithm> `std::accumulate()` function
1670// to accumulate the element values of a container to `init` and return that
1671// accumulation by value.
1672//
1673// Note: Due to a language technicality this function has return type
1674// absl::decay_t<T>. As a user of this function you can casually read
1675// this as "returns T by value" and assume it does the right thing.
1676template <typename Sequence, typename T>
1677decay_t<T> c_accumulate(const Sequence& sequence, T&& init) {
1678 return std::accumulate(container_algorithm_internal::c_begin(sequence),
1679 container_algorithm_internal::c_end(sequence),
1680 std::forward<T>(init));
1681}
1682
1683// Overload of c_accumulate() for using a binary operations other than
1684// addition for computing the accumulation.
1685template <typename Sequence, typename T, typename BinaryOp>
1686decay_t<T> c_accumulate(const Sequence& sequence, T&& init,
1687 BinaryOp&& binary_op) {
1688 return std::accumulate(container_algorithm_internal::c_begin(sequence),
1689 container_algorithm_internal::c_end(sequence),
1690 std::forward<T>(init),
1691 std::forward<BinaryOp>(binary_op));
1692}
1693
1694// c_inner_product()
1695//
1696// Container-based version of the <algorithm> `std::inner_product()` function
1697// to compute the cumulative inner product of container element pairs.
1698//
1699// Note: Due to a language technicality this function has return type
1700// absl::decay_t<T>. As a user of this function you can casually read
1701// this as "returns T by value" and assume it does the right thing.
1702template <typename Sequence1, typename Sequence2, typename T>
1703decay_t<T> c_inner_product(const Sequence1& factors1, const Sequence2& factors2,
1704 T&& sum) {
1705 return std::inner_product(container_algorithm_internal::c_begin(factors1),
1706 container_algorithm_internal::c_end(factors1),
1707 container_algorithm_internal::c_begin(factors2),
1708 std::forward<T>(sum));
1709}
1710
1711// Overload of c_inner_product() for using binary operations other than
1712// `operator+` (for computing the accumulation) and `operator*` (for computing
1713// the product between the two container's element pair).
1714template <typename Sequence1, typename Sequence2, typename T,
1715 typename BinaryOp1, typename BinaryOp2>
1716decay_t<T> c_inner_product(const Sequence1& factors1, const Sequence2& factors2,
1717 T&& sum, BinaryOp1&& op1, BinaryOp2&& op2) {
1718 return std::inner_product(container_algorithm_internal::c_begin(factors1),
1719 container_algorithm_internal::c_end(factors1),
1720 container_algorithm_internal::c_begin(factors2),
1721 std::forward<T>(sum), std::forward<BinaryOp1>(op1),
1722 std::forward<BinaryOp2>(op2));
1723}
1724
1725// c_adjacent_difference()
1726//
1727// Container-based version of the <algorithm> `std::adjacent_difference()`
1728// function to compute the difference between each element and the one preceding
1729// it and write it to an iterator.
1730template <typename InputSequence, typename OutputIt>
1731OutputIt c_adjacent_difference(const InputSequence& input,
1732 OutputIt output_first) {
1733 return std::adjacent_difference(container_algorithm_internal::c_begin(input),
1734 container_algorithm_internal::c_end(input),
1735 output_first);
1736}
1737
1738// Overload of c_adjacent_difference() for using a binary operation other than
1739// subtraction to compute the adjacent difference.
1740template <typename InputSequence, typename OutputIt, typename BinaryOp>
1741OutputIt c_adjacent_difference(const InputSequence& input,
1742 OutputIt output_first, BinaryOp&& op) {
1743 return std::adjacent_difference(container_algorithm_internal::c_begin(input),
1744 container_algorithm_internal::c_end(input),
1745 output_first, std::forward<BinaryOp>(op));
1746}
1747
1748// c_partial_sum()
1749//
1750// Container-based version of the <algorithm> `std::partial_sum()` function
1751// to compute the partial sum of the elements in a sequence and write them
1752// to an iterator. The partial sum is the sum of all element values so far in
1753// the sequence.
1754template <typename InputSequence, typename OutputIt>
1755OutputIt c_partial_sum(const InputSequence& input, OutputIt output_first) {
1756 return std::partial_sum(container_algorithm_internal::c_begin(input),
1757 container_algorithm_internal::c_end(input),
1758 output_first);
1759}
1760
1761// Overload of c_partial_sum() for using a binary operation other than addition
1762// to compute the "partial sum".
1763template <typename InputSequence, typename OutputIt, typename BinaryOp>
1764OutputIt c_partial_sum(const InputSequence& input, OutputIt output_first,
1765 BinaryOp&& op) {
1766 return std::partial_sum(container_algorithm_internal::c_begin(input),
1767 container_algorithm_internal::c_end(input),
1768 output_first, std::forward<BinaryOp>(op));
1769}
1770
1771ABSL_NAMESPACE_END
1772} // namespace absl
1773
1774#endif // ABSL_ALGORITHM_CONTAINER_H_
1775