1/*
2 * Copyright (c) Facebook, Inc. and its affiliates.
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17// @author Mark Rabkin ([email protected])
18// @author Andrei Alexandrescu ([email protected])
19
20#pragma once
21
22#include <folly/Portability.h>
23#include <folly/hash/SpookyHashV2.h>
24#include <folly/lang/Exception.h>
25#include <folly/portability/Constexpr.h>
26#include <folly/portability/String.h>
27
28#include <algorithm>
29#include <array>
30#include <cassert>
31#include <climits>
32#include <cstddef>
33#include <cstring>
34#include <iosfwd>
35#include <iterator>
36#include <stdexcept>
37#include <string>
38#include <type_traits>
39
40#if FOLLY_HAS_STRING_VIEW
41#include <string_view> // @manual
42#endif
43
44#include <folly/CpuId.h>
45#include <folly/Likely.h>
46#include <folly/Traits.h>
47#include <folly/detail/RangeCommon.h>
48#include <folly/detail/RangeSse42.h>
49
50// Ignore shadowing warnings within this file, so includers can use -Wshadow.
51FOLLY_PUSH_WARNING
52FOLLY_GNU_DISABLE_WARNING("-Wshadow")
53
54namespace folly {
55
56/**
57 * Ubiquitous helper template for knowing what's a string.
58 */
59template <class T>
60struct IsSomeString : std::false_type {};
61
62template <typename Alloc>
63struct IsSomeString<std::basic_string<char, std::char_traits<char>, Alloc>>
64 : std::true_type {};
65
66template <class Iter>
67class Range;
68
69/**
70 * Finds the first occurrence of needle in haystack. The algorithm is on
71 * average faster than O(haystack.size() * needle.size()) but not as fast
72 * as Boyer-Moore. On the upside, it does not do any upfront
73 * preprocessing and does not allocate memory.
74 */
75template <
76 class Iter,
77 class Comp = std::equal_to<typename Range<Iter>::value_type>>
78inline size_t
79qfind(const Range<Iter>& haystack, const Range<Iter>& needle, Comp eq = Comp());
80
81/**
82 * Finds the first occurrence of needle in haystack. The result is the
83 * offset reported to the beginning of haystack, or string::npos if
84 * needle wasn't found.
85 */
86template <class Iter>
87size_t qfind(
88 const Range<Iter>& haystack,
89 const typename Range<Iter>::value_type& needle);
90
91/**
92 * Finds the last occurrence of needle in haystack. The result is the
93 * offset reported to the beginning of haystack, or string::npos if
94 * needle wasn't found.
95 */
96template <class Iter>
97size_t rfind(
98 const Range<Iter>& haystack,
99 const typename Range<Iter>::value_type& needle);
100
101/**
102 * Finds the first occurrence of any element of needle in
103 * haystack. The algorithm is O(haystack.size() * needle.size()).
104 */
105template <class Iter>
106inline size_t qfind_first_of(
107 const Range<Iter>& haystack,
108 const Range<Iter>& needle);
109
110/**
111 * Small internal helper - returns the value just before an iterator.
112 */
113namespace detail {
114
115/*
116 * Use IsCharPointer<T>::type to enable const char* or char*.
117 * Use IsCharPointer<T>::const_type to enable only const char*.
118 */
119template <class T>
120struct IsCharPointer {};
121
122template <>
123struct IsCharPointer<char*> {
124 typedef int type;
125};
126
127template <>
128struct IsCharPointer<const char*> {
129 typedef int const_type;
130 typedef int type;
131};
132
133} // namespace detail
134
135/**
136 * Range abstraction keeping a pair of iterators. We couldn't use
137 * boost's similar range abstraction because we need an API identical
138 * with the former StringPiece class, which is used by a lot of other
139 * code. This abstraction does fulfill the needs of boost's
140 * range-oriented algorithms though.
141 *
142 * (Keep memory lifetime in mind when using this class, since it
143 * doesn't manage the data it refers to - just like an iterator
144 * wouldn't.)
145 */
146template <class Iter>
147class Range {
148 private:
149 template <typename Alloc>
150 using string = std::basic_string<char, std::char_traits<char>, Alloc>;
151
152 public:
153 typedef std::size_t size_type;
154 typedef Iter iterator;
155 typedef Iter const_iterator;
156 typedef typename std::remove_reference<
157 typename std::iterator_traits<Iter>::reference>::type value_type;
158 using difference_type = typename std::iterator_traits<Iter>::difference_type;
159 typedef typename std::iterator_traits<Iter>::reference reference;
160
161 /**
162 * For MutableStringPiece and MutableByteRange we define StringPiece
163 * and ByteRange as const_range_type (for everything else its just
164 * identity). We do that to enable operations such as find with
165 * args which are const.
166 */
167 typedef typename std::conditional<
168 std::is_same<Iter, char*>::value ||
169 std::is_same<Iter, unsigned char*>::value,
170 Range<const value_type*>,
171 Range<Iter>>::type const_range_type;
172
173 typedef std::char_traits<typename std::remove_const<value_type>::type>
174 traits_type;
175
176 static const size_type npos;
177
178 // Works for all iterators
179 constexpr Range() : b_(), e_() {}
180
181 constexpr Range(const Range&) = default;
182 constexpr Range(Range&&) = default;
183
184 public:
185 // Works for all iterators
186 constexpr Range(Iter start, Iter end) : b_(start), e_(end) {}
187
188 // Works only for random-access iterators
189 constexpr Range(Iter start, size_t size) : b_(start), e_(start + size) {}
190
191 /* implicit */ Range(std::nullptr_t) = delete;
192
193 constexpr /* implicit */ Range(Iter str)
194 : b_(str), e_(str + constexpr_strlen(str)) {
195 static_assert(
196 std::is_same<int, typename detail::IsCharPointer<Iter>::type>::value,
197 "This constructor is only available for character ranges");
198 }
199
200 template <
201 class Alloc,
202 class T = Iter,
203 typename detail::IsCharPointer<T>::const_type = 0>
204 /* implicit */ Range(const string<Alloc>& str)
205 : b_(str.data()), e_(b_ + str.size()) {}
206
207 template <
208 class Alloc,
209 class T = Iter,
210 typename detail::IsCharPointer<T>::const_type = 0>
211 Range(const string<Alloc>& str, typename string<Alloc>::size_type startFrom) {
212 if (UNLIKELY(startFrom > str.size())) {
213 throw_exception<std::out_of_range>("index out of range");
214 }
215 b_ = str.data() + startFrom;
216 e_ = str.data() + str.size();
217 }
218
219 template <
220 class Alloc,
221 class T = Iter,
222 typename detail::IsCharPointer<T>::const_type = 0>
223 Range(
224 const string<Alloc>& str,
225 typename string<Alloc>::size_type startFrom,
226 typename string<Alloc>::size_type size) {
227 if (UNLIKELY(startFrom > str.size())) {
228 throw_exception<std::out_of_range>("index out of range");
229 }
230 b_ = str.data() + startFrom;
231 if (str.size() - startFrom < size) {
232 e_ = str.data() + str.size();
233 } else {
234 e_ = b_ + size;
235 }
236 }
237
238 Range(const Range& other, size_type first, size_type length = npos)
239 : Range(other.subpiece(first, length)) {}
240
241 template <
242 class Container,
243 class = typename std::enable_if<
244 std::is_same<Iter, typename Container::const_pointer>::value>::type,
245 class = decltype(
246 Iter(std::declval<Container const&>().data()),
247 Iter(
248 std::declval<Container const&>().data() +
249 std::declval<Container const&>().size()))>
250 /* implicit */ constexpr Range(Container const& container)
251 : b_(container.data()), e_(b_ + container.size()) {}
252
253 template <
254 class Container,
255 class = typename std::enable_if<
256 std::is_same<Iter, typename Container::const_pointer>::value>::type,
257 class = decltype(
258 Iter(std::declval<Container const&>().data()),
259 Iter(
260 std::declval<Container const&>().data() +
261 std::declval<Container const&>().size()))>
262 Range(Container const& container, typename Container::size_type startFrom) {
263 auto const cdata = container.data();
264 auto const csize = container.size();
265 if (UNLIKELY(startFrom > csize)) {
266 throw_exception<std::out_of_range>("index out of range");
267 }
268 b_ = cdata + startFrom;
269 e_ = cdata + csize;
270 }
271
272 template <
273 class Container,
274 class = typename std::enable_if<
275 std::is_same<Iter, typename Container::const_pointer>::value>::type,
276 class = decltype(
277 Iter(std::declval<Container const&>().data()),
278 Iter(
279 std::declval<Container const&>().data() +
280 std::declval<Container const&>().size()))>
281 Range(
282 Container const& container,
283 typename Container::size_type startFrom,
284 typename Container::size_type size) {
285 auto const cdata = container.data();
286 auto const csize = container.size();
287 if (UNLIKELY(startFrom > csize)) {
288 throw_exception<std::out_of_range>("index out of range");
289 }
290 b_ = cdata + startFrom;
291 if (csize - startFrom < size) {
292 e_ = cdata + csize;
293 } else {
294 e_ = b_ + size;
295 }
296 }
297
298 // Allow implicit conversion from Range<const char*> (aka StringPiece) to
299 // Range<const unsigned char*> (aka ByteRange), as they're both frequently
300 // used to represent ranges of bytes. Allow explicit conversion in the other
301 // direction.
302 template <
303 class OtherIter,
304 typename std::enable_if<
305 (std::is_same<Iter, const unsigned char*>::value &&
306 (std::is_same<OtherIter, const char*>::value ||
307 std::is_same<OtherIter, char*>::value)),
308 int>::type = 0>
309 /* implicit */ Range(const Range<OtherIter>& other)
310 : b_(reinterpret_cast<const unsigned char*>(other.begin())),
311 e_(reinterpret_cast<const unsigned char*>(other.end())) {}
312
313 template <
314 class OtherIter,
315 typename std::enable_if<
316 (std::is_same<Iter, unsigned char*>::value &&
317 std::is_same<OtherIter, char*>::value),
318 int>::type = 0>
319 /* implicit */ Range(const Range<OtherIter>& other)
320 : b_(reinterpret_cast<unsigned char*>(other.begin())),
321 e_(reinterpret_cast<unsigned char*>(other.end())) {}
322
323 template <
324 class OtherIter,
325 typename std::enable_if<
326 (std::is_same<Iter, const char*>::value &&
327 (std::is_same<OtherIter, const unsigned char*>::value ||
328 std::is_same<OtherIter, unsigned char*>::value)),
329 int>::type = 0>
330 explicit Range(const Range<OtherIter>& other)
331 : b_(reinterpret_cast<const char*>(other.begin())),
332 e_(reinterpret_cast<const char*>(other.end())) {}
333
334 template <
335 class OtherIter,
336 typename std::enable_if<
337 (std::is_same<Iter, char*>::value &&
338 std::is_same<OtherIter, unsigned char*>::value),
339 int>::type = 0>
340 explicit Range(const Range<OtherIter>& other)
341 : b_(reinterpret_cast<char*>(other.begin())),
342 e_(reinterpret_cast<char*>(other.end())) {}
343
344 // Allow implicit conversion from Range<From> to Range<To> if From is
345 // implicitly convertible to To.
346 template <
347 class OtherIter,
348 typename std::enable_if<
349 (!std::is_same<Iter, OtherIter>::value &&
350 std::is_convertible<OtherIter, Iter>::value),
351 int>::type = 0>
352 constexpr /* implicit */ Range(const Range<OtherIter>& other)
353 : b_(other.begin()), e_(other.end()) {}
354
355 // Allow explicit conversion from Range<From> to Range<To> if From is
356 // explicitly convertible to To.
357 template <
358 class OtherIter,
359 typename std::enable_if<
360 (!std::is_same<Iter, OtherIter>::value &&
361 !std::is_convertible<OtherIter, Iter>::value &&
362 std::is_constructible<Iter, const OtherIter&>::value),
363 int>::type = 0>
364 constexpr explicit Range(const Range<OtherIter>& other)
365 : b_(other.begin()), e_(other.end()) {}
366
367 /**
368 * Allow explicit construction of Range() from a std::array of a
369 * convertible type.
370 *
371 * For instance, this allows constructing StringPiece from a
372 * std::array<char, N> or a std::array<const char, N>
373 */
374 template <
375 class T,
376 size_t N,
377 typename = typename std::enable_if<
378 std::is_convertible<const T*, Iter>::value>::type>
379 constexpr explicit Range(const std::array<T, N>& array)
380 : b_{array.empty() ? nullptr : &array.at(0)},
381 e_{array.empty() ? nullptr : &array.at(0) + N} {}
382 template <
383 class T,
384 size_t N,
385 typename =
386 typename std::enable_if<std::is_convertible<T*, Iter>::value>::type>
387 constexpr explicit Range(std::array<T, N>& array)
388 : b_{array.empty() ? nullptr : &array.at(0)},
389 e_{array.empty() ? nullptr : &array.at(0) + N} {}
390
391 Range& operator=(const Range& rhs) & = default;
392 Range& operator=(Range&& rhs) & = default;
393
394 template <
395 class Alloc,
396 class T = Iter,
397 typename detail::IsCharPointer<T>::const_type = 0>
398 Range& operator=(string<Alloc>&& rhs) = delete;
399
400 void clear() {
401 b_ = Iter();
402 e_ = Iter();
403 }
404
405 void assign(Iter start, Iter end) {
406 b_ = start;
407 e_ = end;
408 }
409
410 void reset(Iter start, size_type size) {
411 b_ = start;
412 e_ = start + size;
413 }
414
415 // Works only for Range<const char*>
416 template <typename Alloc>
417 void reset(const string<Alloc>& str) {
418 reset(str.data(), str.size());
419 }
420
421 constexpr size_type size() const {
422#if __clang__ || !__GNUC__ || __GNUC__ >= 7
423 assert(b_ <= e_);
424#endif
425 return size_type(e_ - b_);
426 }
427 constexpr size_type walk_size() const {
428 return size_type(std::distance(b_, e_));
429 }
430 constexpr bool empty() const {
431 return b_ == e_;
432 }
433 constexpr Iter data() const {
434 return b_;
435 }
436 constexpr Iter start() const {
437 return b_;
438 }
439 constexpr Iter begin() const {
440 return b_;
441 }
442 constexpr Iter end() const {
443 return e_;
444 }
445 constexpr Iter cbegin() const {
446 return b_;
447 }
448 constexpr Iter cend() const {
449 return e_;
450 }
451 value_type& front() {
452 assert(b_ < e_);
453 return *b_;
454 }
455 value_type& back() {
456 assert(b_ < e_);
457 return *std::prev(e_);
458 }
459 const value_type& front() const {
460 assert(b_ < e_);
461 return *b_;
462 }
463 const value_type& back() const {
464 assert(b_ < e_);
465 return *std::prev(e_);
466 }
467
468 private:
469 // It would be nice to be able to implicit convert to any target type
470 // T for which either an (Iter, Iter) or (Iter, size_type) noexcept
471 // constructor was available, and explicitly convert to any target
472 // type for which those signatures were available but not noexcept.
473 // The problem is that this creates ambiguity when there is also a
474 // T constructor that takes a type U that is implicitly convertible
475 // from Range.
476 //
477 // To avoid ambiguity, we need to avoid having explicit operator T
478 // and implicit operator U coexist when T is constructible from U.
479 // U cannot be deduced when searching for operator T (and C++ won't
480 // perform an existential search for it), so we must limit the implicit
481 // target types to a finite set that we can enumerate.
482 //
483 // At the moment the set of implicit target types consists of just
484 // std::string_view (when it is available).
485#if FOLLY_HAS_STRING_VIEW
486 struct NotStringView {};
487 template <typename ValueType>
488 struct StringViewType
489 : std::conditional<
490 std::is_pod<std::remove_const_t<ValueType>>::value,
491 std::basic_string_view<std::remove_const_t<ValueType>>,
492 NotStringView> {};
493
494 template <typename Target>
495 struct IsConstructibleViaStringView
496 : Conjunction<
497 std::is_constructible<
498 _t<StringViewType<value_type>>,
499 Iter const&,
500 size_type>,
501 std::is_constructible<Target, _t<StringViewType<value_type>>>> {};
502#else
503 template <typename Target>
504 using IsConstructibleViaStringView = std::false_type;
505#endif
506
507 public:
508 /// explicit operator conversion to any compatible type
509 ///
510 /// A compatible type is one which is constructible with an iterator and a
511 /// size (preferred), or a pair of iterators (fallback), passed by const-ref.
512 ///
513 /// Participates in overload resolution precisely when the target type is
514 /// compatible. This allows std::is_constructible compile-time checks to work.
515 template <
516 typename Tgt,
517 std::enable_if_t<
518 std::is_constructible<Tgt, Iter const&, size_type>::value &&
519 !IsConstructibleViaStringView<Tgt>::value,
520 int> = 0>
521 constexpr explicit operator Tgt() const noexcept(
522 std::is_nothrow_constructible<Tgt, Iter const&, size_type>::value) {
523 return Tgt(b_, walk_size());
524 }
525 template <
526 typename Tgt,
527 std::enable_if_t<
528 !std::is_constructible<Tgt, Iter const&, size_type>::value &&
529 std::is_constructible<Tgt, Iter const&, Iter const&>::value &&
530 !IsConstructibleViaStringView<Tgt>::value,
531 int> = 0>
532 constexpr explicit operator Tgt() const noexcept(
533 std::is_nothrow_constructible<Tgt, Iter const&, Iter const&>::value) {
534 return Tgt(b_, e_);
535 }
536
537#if FOLLY_HAS_STRING_VIEW
538 /// implicit operator conversion to std::string_view
539 template <
540 typename Tgt,
541 typename ValueType = value_type,
542 std::enable_if_t<
543 StrictConjunction<
544 std::is_same<Tgt, _t<StringViewType<ValueType>>>,
545 std::is_constructible<
546 _t<StringViewType<ValueType>>,
547 Iter const&,
548 size_type>>::value,
549 int> = 0>
550 constexpr operator Tgt() const noexcept(
551 std::is_nothrow_constructible<Tgt, Iter const&, size_type>::value) {
552 return Tgt(b_, walk_size());
553 }
554#endif
555
556 /// explicit non-operator conversion to any compatible type
557 ///
558 /// A compatible type is one which is constructible with an iterator and a
559 /// size (preferred), or a pair of iterators (fallback), passed by const-ref.
560 ///
561 /// Participates in overload resolution precisely when the target type is
562 /// compatible. This allows is_invocable compile-time checks to work.
563 ///
564 /// Provided in addition to the explicit operator conversion to permit passing
565 /// additional arguments to the target type constructor. A canonical example
566 /// of an additional argument might be an allocator, where the target type is
567 /// some specialization of std::vector or std::basic_string in a context which
568 /// requires a non-default-constructed allocator.
569 template <typename Tgt, typename... Args>
570 constexpr std::enable_if_t<
571 std::is_constructible<Tgt, Iter const&, size_type>::value,
572 Tgt>
573 to(Args&&... args) const noexcept(
574 std::is_nothrow_constructible<Tgt, Iter const&, size_type, Args&&...>::
575 value) {
576 return Tgt(b_, walk_size(), static_cast<Args&&>(args)...);
577 }
578 template <typename Tgt, typename... Args>
579 constexpr std::enable_if_t<
580 !std::is_constructible<Tgt, Iter const&, size_type>::value &&
581 std::is_constructible<Tgt, Iter const&, Iter const&>::value,
582 Tgt>
583 to(Args&&... args) const noexcept(
584 std::is_nothrow_constructible<Tgt, Iter const&, Iter const&, Args&&...>::
585 value) {
586 return Tgt(b_, e_, static_cast<Args&&>(args)...);
587 }
588
589 // Works only for Range<const char*> and Range<char*>
590 std::string str() const {
591 return to<std::string>();
592 }
593 std::string toString() const {
594 return to<std::string>();
595 }
596
597 const_range_type castToConst() const {
598 return const_range_type(*this);
599 }
600
601 int compare(const const_range_type& o) const {
602 const size_type tsize = this->size();
603 const size_type osize = o.size();
604 const size_type msize = std::min(tsize, osize);
605 int r = traits_type::compare(data(), o.data(), msize);
606 if (r == 0 && tsize != osize) {
607 // We check the signed bit of the subtraction and bit shift it
608 // to produce either 0 or 2. The subtraction yields the
609 // comparison values of either -1 or 1.
610 r = (static_cast<int>((osize - tsize) >> (CHAR_BIT * sizeof(size_t) - 1))
611 << 1) -
612 1;
613 }
614 return r;
615 }
616
617 value_type& operator[](size_t i) {
618 assert(i < size());
619 return b_[i];
620 }
621
622 const value_type& operator[](size_t i) const {
623 assert(i < size());
624 return b_[i];
625 }
626
627 value_type& at(size_t i) {
628 if (i >= size()) {
629 throw_exception<std::out_of_range>("index out of range");
630 }
631 return b_[i];
632 }
633
634 const value_type& at(size_t i) const {
635 if (i >= size()) {
636 throw_exception<std::out_of_range>("index out of range");
637 }
638 return b_[i];
639 }
640
641 // Do NOT use this function, which was left behind for backwards
642 // compatibility. Use SpookyHashV2 instead -- it is faster, and produces
643 // a 64-bit hash, which means dramatically fewer collisions in large maps.
644 // (The above advice does not apply if you are targeting a 32-bit system.)
645 //
646 // Works only for Range<const char*> and Range<char*>
647 //
648 //
649 // ** WANT TO GET RID OF THIS LINT? **
650 //
651 // A) Use a better hash function (*cough*folly::Hash*cough*), but
652 // only if you don't serialize data in a format that depends on
653 // this formula (ie the writer and reader assume this exact hash
654 // function is used).
655 //
656 // B) If you have to use this exact function then make your own hasher
657 // object and copy the body over (see thrift example: D3972362).
658 // https://github.com/facebook/fbthrift/commit/f8ed502e24ab4a32a9d5f266580
659 [[deprecated(
660 "Replace with folly::Hash if the hash is not serialized")]] uint32_t
661 hash() const {
662 // Taken from fbi/nstring.h:
663 // Quick and dirty bernstein hash...fine for short ascii strings
664 uint32_t hash = 5381;
665 for (size_t ix = 0; ix < size(); ix++) {
666 hash = ((hash << 5) + hash) + b_[ix];
667 }
668 return hash;
669 }
670
671 void advance(size_type n) {
672 if (UNLIKELY(n > size())) {
673 throw_exception<std::out_of_range>("index out of range");
674 }
675 b_ += n;
676 }
677
678 void subtract(size_type n) {
679 if (UNLIKELY(n > size())) {
680 throw_exception<std::out_of_range>("index out of range");
681 }
682 e_ -= n;
683 }
684
685 Range subpiece(size_type first, size_type length = npos) const {
686 if (UNLIKELY(first > size())) {
687 throw_exception<std::out_of_range>("index out of range");
688 }
689
690 return Range(b_ + first, std::min(length, size() - first));
691 }
692
693 // unchecked versions
694 void uncheckedAdvance(size_type n) {
695 assert(n <= size());
696 b_ += n;
697 }
698
699 void uncheckedSubtract(size_type n) {
700 assert(n <= size());
701 e_ -= n;
702 }
703
704 Range uncheckedSubpiece(size_type first, size_type length = npos) const {
705 assert(first <= size());
706 return Range(b_ + first, std::min(length, size() - first));
707 }
708
709 void pop_front() {
710 assert(b_ < e_);
711 ++b_;
712 }
713
714 void pop_back() {
715 assert(b_ < e_);
716 --e_;
717 }
718
719 // string work-alike functions
720 size_type find(const_range_type str) const {
721 return qfind(castToConst(), str);
722 }
723
724 size_type find(const_range_type str, size_t pos) const {
725 if (pos > size()) {
726 return std::string::npos;
727 }
728 size_t ret = qfind(castToConst().subpiece(pos), str);
729 return ret == npos ? ret : ret + pos;
730 }
731
732 size_type find(Iter s, size_t pos, size_t n) const {
733 if (pos > size()) {
734 return std::string::npos;
735 }
736 auto forFinding = castToConst();
737 size_t ret = qfind(
738 pos ? forFinding.subpiece(pos) : forFinding, const_range_type(s, n));
739 return ret == npos ? ret : ret + pos;
740 }
741
742 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
743 size_type find(const Iter s) const {
744 return qfind(castToConst(), const_range_type(s));
745 }
746
747 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
748 size_type find(const Iter s, size_t pos) const {
749 if (pos > size()) {
750 return std::string::npos;
751 }
752 size_type ret = qfind(castToConst().subpiece(pos), const_range_type(s));
753 return ret == npos ? ret : ret + pos;
754 }
755
756 size_type find(value_type c) const {
757 return qfind(castToConst(), c);
758 }
759
760 size_type rfind(value_type c) const {
761 return folly::rfind(castToConst(), c);
762 }
763
764 size_type find(value_type c, size_t pos) const {
765 if (pos > size()) {
766 return std::string::npos;
767 }
768 size_type ret = qfind(castToConst().subpiece(pos), c);
769 return ret == npos ? ret : ret + pos;
770 }
771
772 size_type find_first_of(const_range_type needles) const {
773 return qfind_first_of(castToConst(), needles);
774 }
775
776 size_type find_first_of(const_range_type needles, size_t pos) const {
777 if (pos > size()) {
778 return std::string::npos;
779 }
780 size_type ret = qfind_first_of(castToConst().subpiece(pos), needles);
781 return ret == npos ? ret : ret + pos;
782 }
783
784 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
785 size_type find_first_of(Iter needles) const {
786 return find_first_of(const_range_type(needles));
787 }
788
789 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
790 size_type find_first_of(Iter needles, size_t pos) const {
791 return find_first_of(const_range_type(needles), pos);
792 }
793
794 size_type find_first_of(Iter needles, size_t pos, size_t n) const {
795 return find_first_of(const_range_type(needles, n), pos);
796 }
797
798 size_type find_first_of(value_type c) const {
799 return find(c);
800 }
801
802 size_type find_first_of(value_type c, size_t pos) const {
803 return find(c, pos);
804 }
805
806 /**
807 * Determine whether the range contains the given subrange or item.
808 *
809 * Note: Call find() directly if the index is needed.
810 */
811 bool contains(const const_range_type& other) const {
812 return find(other) != std::string::npos;
813 }
814
815 bool contains(const value_type& other) const {
816 return find(other) != std::string::npos;
817 }
818
819 void swap(Range& rhs) {
820 std::swap(b_, rhs.b_);
821 std::swap(e_, rhs.e_);
822 }
823
824 /**
825 * Does this Range start with another range?
826 */
827 bool startsWith(const const_range_type& other) const {
828 return size() >= other.size() &&
829 castToConst().subpiece(0, other.size()) == other;
830 }
831 bool startsWith(value_type c) const {
832 return !empty() && front() == c;
833 }
834
835 template <class Comp>
836 bool startsWith(const const_range_type& other, Comp&& eq) const {
837 if (size() < other.size()) {
838 return false;
839 }
840 auto const trunc = subpiece(0, other.size());
841 return std::equal(
842 trunc.begin(), trunc.end(), other.begin(), std::forward<Comp>(eq));
843 }
844
845 /**
846 * Does this Range end with another range?
847 */
848 bool endsWith(const const_range_type& other) const {
849 return size() >= other.size() &&
850 castToConst().subpiece(size() - other.size()) == other;
851 }
852 bool endsWith(value_type c) const {
853 return !empty() && back() == c;
854 }
855
856 template <class Comp>
857 bool endsWith(const const_range_type& other, Comp&& eq) const {
858 if (size() < other.size()) {
859 return false;
860 }
861 auto const trunc = subpiece(size() - other.size());
862 return std::equal(
863 trunc.begin(), trunc.end(), other.begin(), std::forward<Comp>(eq));
864 }
865
866 template <class Comp>
867 bool equals(const const_range_type& other, Comp&& eq) const {
868 return size() == other.size() &&
869 std::equal(begin(), end(), other.begin(), std::forward<Comp>(eq));
870 }
871
872 /**
873 * Remove the items in [b, e), as long as this subrange is at the beginning
874 * or end of the Range.
875 *
876 * Required for boost::algorithm::trim()
877 */
878 void erase(Iter b, Iter e) {
879 if (b == b_) {
880 b_ = e;
881 } else if (e == e_) {
882 e_ = b;
883 } else {
884 throw_exception<std::out_of_range>("index out of range");
885 }
886 }
887
888 /**
889 * Remove the given prefix and return true if the range starts with the given
890 * prefix; return false otherwise.
891 */
892 bool removePrefix(const const_range_type& prefix) {
893 return startsWith(prefix) && (b_ += prefix.size(), true);
894 }
895 bool removePrefix(value_type prefix) {
896 return startsWith(prefix) && (++b_, true);
897 }
898
899 /**
900 * Remove the given suffix and return true if the range ends with the given
901 * suffix; return false otherwise.
902 */
903 bool removeSuffix(const const_range_type& suffix) {
904 return endsWith(suffix) && (e_ -= suffix.size(), true);
905 }
906 bool removeSuffix(value_type suffix) {
907 return endsWith(suffix) && (--e_, true);
908 }
909
910 /**
911 * Replaces the content of the range, starting at position 'pos', with
912 * contents of 'replacement'. Entire 'replacement' must fit into the
913 * range. Returns false if 'replacements' does not fit. Example use:
914 *
915 * char in[] = "buffer";
916 * auto msp = MutablesStringPiece(input);
917 * EXPECT_TRUE(msp.replaceAt(2, "tt"));
918 * EXPECT_EQ(msp, "butter");
919 *
920 * // not enough space
921 * EXPECT_FALSE(msp.replace(msp.size() - 1, "rr"));
922 * EXPECT_EQ(msp, "butter"); // unchanged
923 */
924 bool replaceAt(size_t pos, const_range_type replacement) {
925 if (size() < pos + replacement.size()) {
926 return false;
927 }
928
929 std::copy(replacement.begin(), replacement.end(), begin() + pos);
930
931 return true;
932 }
933
934 /**
935 * Replaces all occurences of 'source' with 'dest'. Returns number
936 * of replacements made. Source and dest have to have the same
937 * length. Throws if the lengths are different. If 'source' is a
938 * pattern that is overlapping with itself, we perform sequential
939 * replacement: "aaaaaaa".replaceAll("aa", "ba") --> "bababaa"
940 *
941 * Example use:
942 *
943 * char in[] = "buffer";
944 * auto msp = MutablesStringPiece(input);
945 * EXPECT_EQ(msp.replaceAll("ff","tt"), 1);
946 * EXPECT_EQ(msp, "butter");
947 */
948 size_t replaceAll(const_range_type source, const_range_type dest) {
949 if (source.size() != dest.size()) {
950 throw_exception<std::invalid_argument>(
951 "replacement must have the same size as source");
952 }
953
954 if (dest.empty()) {
955 return 0;
956 }
957
958 size_t pos = 0;
959 size_t num_replaced = 0;
960 size_type found = std::string::npos;
961 while ((found = find(source, pos)) != std::string::npos) {
962 replaceAt(found, dest);
963 pos += source.size();
964 ++num_replaced;
965 }
966
967 return num_replaced;
968 }
969
970 /**
971 * Splits this `Range` `[b, e)` in the position `i` dictated by the next
972 * occurence of `delimiter`.
973 *
974 * Returns a new `Range` `[b, i)` and adjusts this range to start right after
975 * the delimiter's position. This range will be empty if the delimiter is not
976 * found. If called on an empty `Range`, both this and the returned `Range`
977 * will be empty.
978 *
979 * Example:
980 *
981 * folly::StringPiece s("sample string for split_next");
982 * auto p = s.split_step(' ');
983 *
984 * // prints "string for split_next"
985 * cout << s << endl;
986 *
987 * // prints "sample"
988 * cout << p << endl;
989 *
990 * Example 2:
991 *
992 * void tokenize(StringPiece s, char delimiter) {
993 * while (!s.empty()) {
994 * cout << s.split_step(delimiter);
995 * }
996 * }
997 *
998 * @author: Marcelo Juchem <marcelo@fb.com>
999 */
1000 Range split_step(value_type delimiter) {
1001 auto i = std::find(b_, e_, delimiter);
1002 Range result(b_, i);
1003
1004 b_ = i == e_ ? e_ : std::next(i);
1005
1006 return result;
1007 }
1008
1009 Range split_step(Range delimiter) {
1010 auto i = find(delimiter);
1011 Range result(b_, i == std::string::npos ? size() : i);
1012
1013 b_ = result.end() == e_
1014 ? e_
1015 : std::next(
1016 result.end(),
1017 typename std::iterator_traits<Iter>::difference_type(
1018 delimiter.size()));
1019
1020 return result;
1021 }
1022
1023 /**
1024 * Convenience method that calls `split_step()` and passes the result to a
1025 * functor, returning whatever the functor does. Any additional arguments
1026 * `args` passed to this function are perfectly forwarded to the functor.
1027 *
1028 * Say you have a functor with this signature:
1029 *
1030 * Foo fn(Range r) { }
1031 *
1032 * `split_step()`'s return type will be `Foo`. It works just like:
1033 *
1034 * auto result = fn(myRange.split_step(' '));
1035 *
1036 * A functor returning `void` is also supported.
1037 *
1038 * Example:
1039 *
1040 * void do_some_parsing(folly::StringPiece s) {
1041 * auto version = s.split_step(' ', [&](folly::StringPiece x) {
1042 * if (x.empty()) {
1043 * throw std::invalid_argument("empty string");
1044 * }
1045 * return std::strtoull(x.begin(), x.end(), 16);
1046 * });
1047 *
1048 * // ...
1049 * }
1050 *
1051 * struct Foo {
1052 * void parse(folly::StringPiece s) {
1053 * s.split_step(' ', parse_field, bar, 10);
1054 * s.split_step('\t', parse_field, baz, 20);
1055 *
1056 * auto const kludge = [](folly::StringPiece x, int &out, int def) {
1057 * if (x == "null") {
1058 * out = 0;
1059 * } else {
1060 * parse_field(x, out, def);
1061 * }
1062 * };
1063 *
1064 * s.split_step('\t', kludge, gaz);
1065 * s.split_step(' ', kludge, foo);
1066 * }
1067 *
1068 * private:
1069 * int bar;
1070 * int baz;
1071 * int gaz;
1072 * int foo;
1073 *
1074 * static parse_field(folly::StringPiece s, int &out, int def) {
1075 * try {
1076 * out = folly::to<int>(s);
1077 * } catch (std::exception const &) {
1078 * value = def;
1079 * }
1080 * }
1081 * };
1082 *
1083 * @author: Marcelo Juchem <marcelo@fb.com>
1084 */
1085 template <typename TProcess, typename... Args>
1086 auto split_step(value_type delimiter, TProcess&& process, Args&&... args)
1087 -> decltype(process(std::declval<Range>(), std::forward<Args>(args)...)) {
1088 return process(split_step(delimiter), std::forward<Args>(args)...);
1089 }
1090
1091 template <typename TProcess, typename... Args>
1092 auto split_step(Range delimiter, TProcess&& process, Args&&... args)
1093 -> decltype(process(std::declval<Range>(), std::forward<Args>(args)...)) {
1094 return process(split_step(delimiter), std::forward<Args>(args)...);
1095 }
1096
1097 private:
1098 Iter b_, e_;
1099};
1100
1101template <class Iter>
1102const typename Range<Iter>::size_type Range<Iter>::npos = std::string::npos;
1103
1104template <class Iter>
1105void swap(Range<Iter>& lhs, Range<Iter>& rhs) {
1106 lhs.swap(rhs);
1107}
1108
1109/**
1110 * Create a range from two iterators, with type deduction.
1111 */
1112template <class Iter>
1113constexpr Range<Iter> range(Iter first, Iter last) {
1114 return Range<Iter>(first, last);
1115}
1116
1117/*
1118 * Creates a range to reference the contents of a contiguous-storage container.
1119 */
1120// Use pointers for types with '.data()' member
1121template <class Collection>
1122constexpr auto range(Collection& v) -> Range<decltype(v.data())> {
1123 return Range<decltype(v.data())>(v.data(), v.data() + v.size());
1124}
1125template <class Collection>
1126constexpr auto range(Collection const& v) -> Range<decltype(v.data())> {
1127 return Range<decltype(v.data())>(v.data(), v.data() + v.size());
1128}
1129template <class Collection>
1130constexpr auto crange(Collection const& v) -> Range<decltype(v.data())> {
1131 return Range<decltype(v.data())>(v.data(), v.data() + v.size());
1132}
1133
1134template <class T, size_t n>
1135constexpr Range<T*> range(T (&array)[n]) {
1136 return Range<T*>(array, array + n);
1137}
1138template <class T, size_t n>
1139constexpr Range<T const*> range(T const (&array)[n]) {
1140 return Range<T const*>(array, array + n);
1141}
1142template <class T, size_t n>
1143constexpr Range<T const*> crange(T const (&array)[n]) {
1144 return Range<T const*>(array, array + n);
1145}
1146
1147template <class T, size_t n>
1148constexpr Range<T*> range(std::array<T, n>& array) {
1149 return Range<T*>{array};
1150}
1151template <class T, size_t n>
1152constexpr Range<T const*> range(std::array<T, n> const& array) {
1153 return Range<T const*>{array};
1154}
1155template <class T, size_t n>
1156constexpr Range<T const*> crange(std::array<T, n> const& array) {
1157 return Range<T const*>{array};
1158}
1159
1160typedef Range<const char*> StringPiece;
1161typedef Range<char*> MutableStringPiece;
1162typedef Range<const unsigned char*> ByteRange;
1163typedef Range<unsigned char*> MutableByteRange;
1164
1165template <class C>
1166std::basic_ostream<C>& operator<<(
1167 std::basic_ostream<C>& os,
1168 Range<C const*> piece) {
1169 using StreamSize = decltype(os.width());
1170 os.write(piece.start(), static_cast<StreamSize>(piece.size()));
1171 return os;
1172}
1173
1174template <class C>
1175std::basic_ostream<C>& operator<<(std::basic_ostream<C>& os, Range<C*> piece) {
1176 using StreamSize = decltype(os.width());
1177 os.write(piece.start(), static_cast<StreamSize>(piece.size()));
1178 return os;
1179}
1180
1181/**
1182 * Templated comparison operators
1183 */
1184
1185template <class Iter>
1186inline bool operator==(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1187 return lhs.size() == rhs.size() && lhs.compare(rhs) == 0;
1188}
1189
1190template <class Iter>
1191inline bool operator!=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1192 return !(operator==(lhs, rhs));
1193}
1194
1195template <class Iter>
1196inline bool operator<(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1197 return lhs.compare(rhs) < 0;
1198}
1199
1200template <class Iter>
1201inline bool operator<=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1202 return lhs.compare(rhs) <= 0;
1203}
1204
1205template <class Iter>
1206inline bool operator>(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1207 return lhs.compare(rhs) > 0;
1208}
1209
1210template <class Iter>
1211inline bool operator>=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1212 return lhs.compare(rhs) >= 0;
1213}
1214
1215/**
1216 * Specializations of comparison operators for StringPiece
1217 */
1218
1219namespace detail {
1220
1221template <class A, class B>
1222struct ComparableAsStringPiece {
1223 enum {
1224 value = (std::is_convertible<A, StringPiece>::value &&
1225 std::is_same<B, StringPiece>::value) ||
1226 (std::is_convertible<B, StringPiece>::value &&
1227 std::is_same<A, StringPiece>::value)
1228 };
1229};
1230
1231} // namespace detail
1232
1233/**
1234 * operator== through conversion for Range<const char*>
1235 */
1236template <class T, class U>
1237std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator==(
1238 const T& lhs,
1239 const U& rhs) {
1240 return StringPiece(lhs) == StringPiece(rhs);
1241}
1242
1243/**
1244 * operator!= through conversion for Range<const char*>
1245 */
1246template <class T, class U>
1247std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator!=(
1248 const T& lhs,
1249 const U& rhs) {
1250 return StringPiece(lhs) != StringPiece(rhs);
1251}
1252
1253/**
1254 * operator< through conversion for Range<const char*>
1255 */
1256template <class T, class U>
1257std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator<(
1258 const T& lhs,
1259 const U& rhs) {
1260 return StringPiece(lhs) < StringPiece(rhs);
1261}
1262
1263/**
1264 * operator> through conversion for Range<const char*>
1265 */
1266template <class T, class U>
1267std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator>(
1268 const T& lhs,
1269 const U& rhs) {
1270 return StringPiece(lhs) > StringPiece(rhs);
1271}
1272
1273/**
1274 * operator< through conversion for Range<const char*>
1275 */
1276template <class T, class U>
1277std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator<=(
1278 const T& lhs,
1279 const U& rhs) {
1280 return StringPiece(lhs) <= StringPiece(rhs);
1281}
1282
1283/**
1284 * operator> through conversion for Range<const char*>
1285 */
1286template <class T, class U>
1287std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator>=(
1288 const T& lhs,
1289 const U& rhs) {
1290 return StringPiece(lhs) >= StringPiece(rhs);
1291}
1292
1293/**
1294 * Finds substrings faster than brute force by borrowing from Boyer-Moore
1295 */
1296template <class Iter, class Comp>
1297size_t qfind(const Range<Iter>& haystack, const Range<Iter>& needle, Comp eq) {
1298 // Don't use std::search, use a Boyer-Moore-like trick by comparing
1299 // the last characters first
1300 auto const nsize = needle.size();
1301 if (haystack.size() < nsize) {
1302 return std::string::npos;
1303 }
1304 if (!nsize) {
1305 return 0;
1306 }
1307 auto const nsize_1 = nsize - 1;
1308 auto const lastNeedle = needle[nsize_1];
1309
1310 // Boyer-Moore skip value for the last char in the needle. Zero is
1311 // not a valid value; skip will be computed the first time it's
1312 // needed.
1313 std::string::size_type skip = 0;
1314
1315 auto i = haystack.begin();
1316 auto iEnd = haystack.end() - nsize_1;
1317
1318 while (i < iEnd) {
1319 // Boyer-Moore: match the last element in the needle
1320 while (!eq(i[nsize_1], lastNeedle)) {
1321 if (++i == iEnd) {
1322 // not found
1323 return std::string::npos;
1324 }
1325 }
1326 // Here we know that the last char matches
1327 // Continue in pedestrian mode
1328 for (size_t j = 0;;) {
1329 assert(j < nsize);
1330 if (!eq(i[j], needle[j])) {
1331 // Not found, we can skip
1332 // Compute the skip value lazily
1333 if (skip == 0) {
1334 skip = 1;
1335 while (skip <= nsize_1 && !eq(needle[nsize_1 - skip], lastNeedle)) {
1336 ++skip;
1337 }
1338 }
1339 i += skip;
1340 break;
1341 }
1342 // Check if done searching
1343 if (++j == nsize) {
1344 // Yay
1345 return size_t(i - haystack.begin());
1346 }
1347 }
1348 }
1349 return std::string::npos;
1350}
1351
1352namespace detail {
1353
1354inline size_t qfind_first_byte_of(
1355 const StringPiece haystack,
1356 const StringPiece needles) {
1357 static auto const qfind_first_byte_of_fn = folly::CpuId().sse42()
1358 ? qfind_first_byte_of_sse42
1359 : qfind_first_byte_of_nosse;
1360 return qfind_first_byte_of_fn(haystack, needles);
1361}
1362
1363} // namespace detail
1364
1365template <class Iter, class Comp>
1366size_t qfind_first_of(
1367 const Range<Iter>& haystack,
1368 const Range<Iter>& needles,
1369 Comp eq) {
1370 auto ret = std::find_first_of(
1371 haystack.begin(), haystack.end(), needles.begin(), needles.end(), eq);
1372 return ret == haystack.end() ? std::string::npos : ret - haystack.begin();
1373}
1374
1375struct AsciiCaseSensitive {
1376 bool operator()(char lhs, char rhs) const {
1377 return lhs == rhs;
1378 }
1379};
1380
1381/**
1382 * Check if two ascii characters are case insensitive equal.
1383 * The difference between the lower/upper case characters are the 6-th bit.
1384 * We also check they are alpha chars, in case of xor = 32.
1385 */
1386struct AsciiCaseInsensitive {
1387 bool operator()(char lhs, char rhs) const {
1388 char k = lhs ^ rhs;
1389 if (k == 0) {
1390 return true;
1391 }
1392 if (k != 32) {
1393 return false;
1394 }
1395 k = lhs | rhs;
1396 return (k >= 'a' && k <= 'z');
1397 }
1398};
1399
1400template <class Iter>
1401size_t qfind(
1402 const Range<Iter>& haystack,
1403 const typename Range<Iter>::value_type& needle) {
1404 auto pos = std::find(haystack.begin(), haystack.end(), needle);
1405 return pos == haystack.end() ? std::string::npos : pos - haystack.data();
1406}
1407
1408template <class Iter>
1409size_t rfind(
1410 const Range<Iter>& haystack,
1411 const typename Range<Iter>::value_type& needle) {
1412 for (auto i = haystack.size(); i-- > 0;) {
1413 if (haystack[i] == needle) {
1414 return i;
1415 }
1416 }
1417 return std::string::npos;
1418}
1419
1420// specialization for StringPiece
1421template <>
1422inline size_t qfind(const Range<const char*>& haystack, const char& needle) {
1423 // memchr expects a not-null pointer, early return if the range is empty.
1424 if (haystack.empty()) {
1425 return std::string::npos;
1426 }
1427 auto pos = static_cast<const char*>(
1428 ::memchr(haystack.data(), needle, haystack.size()));
1429 return pos == nullptr ? std::string::npos : pos - haystack.data();
1430}
1431
1432template <>
1433inline size_t rfind(const Range<const char*>& haystack, const char& needle) {
1434 // memchr expects a not-null pointer, early return if the range is empty.
1435 if (haystack.empty()) {
1436 return std::string::npos;
1437 }
1438 auto pos = static_cast<const char*>(
1439 ::memrchr(haystack.data(), needle, haystack.size()));
1440 return pos == nullptr ? std::string::npos : pos - haystack.data();
1441}
1442
1443// specialization for ByteRange
1444template <>
1445inline size_t qfind(
1446 const Range<const unsigned char*>& haystack,
1447 const unsigned char& needle) {
1448 // memchr expects a not-null pointer, early return if the range is empty.
1449 if (haystack.empty()) {
1450 return std::string::npos;
1451 }
1452 auto pos = static_cast<const unsigned char*>(
1453 ::memchr(haystack.data(), needle, haystack.size()));
1454 return pos == nullptr ? std::string::npos : pos - haystack.data();
1455}
1456
1457template <>
1458inline size_t rfind(
1459 const Range<const unsigned char*>& haystack,
1460 const unsigned char& needle) {
1461 // memchr expects a not-null pointer, early return if the range is empty.
1462 if (haystack.empty()) {
1463 return std::string::npos;
1464 }
1465 auto pos = static_cast<const unsigned char*>(
1466 ::memrchr(haystack.data(), needle, haystack.size()));
1467 return pos == nullptr ? std::string::npos : pos - haystack.data();
1468}
1469
1470template <class Iter>
1471size_t qfind_first_of(const Range<Iter>& haystack, const Range<Iter>& needles) {
1472 return qfind_first_of(haystack, needles, AsciiCaseSensitive());
1473}
1474
1475// specialization for StringPiece
1476template <>
1477inline size_t qfind_first_of(
1478 const Range<const char*>& haystack,
1479 const Range<const char*>& needles) {
1480 return detail::qfind_first_byte_of(haystack, needles);
1481}
1482
1483// specialization for ByteRange
1484template <>
1485inline size_t qfind_first_of(
1486 const Range<const unsigned char*>& haystack,
1487 const Range<const unsigned char*>& needles) {
1488 return detail::qfind_first_byte_of(
1489 StringPiece(haystack), StringPiece(needles));
1490}
1491
1492template <class Key, class Enable>
1493struct hasher;
1494
1495template <class T>
1496struct hasher<
1497 folly::Range<T*>,
1498 std::enable_if_t<std::is_integral<T>::value, void>> {
1499 using folly_is_avalanching = std::true_type;
1500
1501 size_t operator()(folly::Range<T*> r) const {
1502 // std::is_integral<T> is too restrictive, but is sufficient to
1503 // guarantee we can just hash all of the underlying bytes to get a
1504 // suitable hash of T. Something like absl::is_uniquely_represented<T>
1505 // would be better. std::is_pod is not enough, because POD types
1506 // can contain pointers and padding. Also, floating point numbers
1507 // may be == without being bit-identical.
1508 return hash::SpookyHashV2::Hash64(r.begin(), r.size() * sizeof(T), 0);
1509 }
1510};
1511
1512/**
1513 * _sp is a user-defined literal suffix to make an appropriate Range
1514 * specialization from a literal string.
1515 *
1516 * Modeled after C++17's `sv` suffix.
1517 */
1518inline namespace literals {
1519inline namespace string_piece_literals {
1520constexpr Range<char const*> operator"" _sp(
1521 char const* str,
1522 size_t len) noexcept {
1523 return Range<char const*>(str, len);
1524}
1525
1526constexpr Range<char16_t const*> operator"" _sp(
1527 char16_t const* str,
1528 size_t len) noexcept {
1529 return Range<char16_t const*>(str, len);
1530}
1531
1532constexpr Range<char32_t const*> operator"" _sp(
1533 char32_t const* str,
1534 size_t len) noexcept {
1535 return Range<char32_t const*>(str, len);
1536}
1537
1538constexpr Range<wchar_t const*> operator"" _sp(
1539 wchar_t const* str,
1540 size_t len) noexcept {
1541 return Range<wchar_t const*>(str, len);
1542}
1543} // namespace string_piece_literals
1544} // namespace literals
1545
1546} // namespace folly
1547
1548FOLLY_POP_WARNING
1549
1550FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(folly::Range)
1551