2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 // @author: Andrei Alexandrescu (aalexandre)
24 #include <type_traits>
26 // This file appears in two locations: inside fbcode and in the
27 // libstdc++ source code (when embedding fbstring as std::string).
28 // To aid in this schizophrenic use, _LIBSTDCXX_FBSTRING is defined in
29 // libstdc++'s c++config.h, to gate use inside fbcode v. libstdc++.
30 #ifdef _LIBSTDCXX_FBSTRING
32 #pragma GCC system_header
34 // When used as std::string replacement always disable assertions.
37 #define FOLLY_DEFINED_NDEBUG_FOR_FBSTRING
40 // Handle the cases where the fbcode version (folly/Malloc.h) is included
41 // either before or after this inclusion.
42 #ifdef FOLLY_MALLOC_H_
43 #undef FOLLY_MALLOC_H_
44 #include "basic_fbstring_malloc.h" // nolint
46 #include "basic_fbstring_malloc.h" // nolint
47 #undef FOLLY_MALLOC_H_
50 #else // !_LIBSTDCXX_FBSTRING
52 #include <folly/Portability.h>
54 // libc++ doesn't provide this header, nor does msvc
55 #ifdef FOLLY_HAVE_BITS_CXXCONFIG_H
56 #include <bits/c++config.h>
64 #include <folly/Traits.h>
65 #include <folly/Malloc.h>
66 #include <folly/Hash.h>
67 #include <folly/ScopeGuard.h>
69 #if FOLLY_HAVE_DEPRECATED_ASSOC
70 #ifdef _GLIBCXX_SYMVER
71 #include <ext/hash_set>
72 #include <ext/hash_map>
78 // We defined these here rather than including Likely.h to avoid
79 // redefinition errors when fbstring is imported into libstdc++.
80 #if defined(__GNUC__) && __GNUC__ >= 4
81 #define FBSTRING_LIKELY(x) (__builtin_expect((x), 1))
82 #define FBSTRING_UNLIKELY(x) (__builtin_expect((x), 0))
84 #define FBSTRING_LIKELY(x) (x)
85 #define FBSTRING_UNLIKELY(x) (x)
88 #pragma GCC diagnostic push
89 // Ignore shadowing warnings within this file, so includers can use -Wshadow.
90 #pragma GCC diagnostic ignored "-Wshadow"
91 // GCC 4.9 has a false positive in setSmallSize (probably
92 // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59124), disable
93 // compile-time array bound checking.
94 #pragma GCC diagnostic ignored "-Warray-bounds"
96 // FBString cannot use throw when replacing std::string, though it may still
99 #define throw FOLLY_FBSTRING_MAY_NOT_USE_THROW
101 #ifdef _LIBSTDCXX_FBSTRING
102 namespace std _GLIBCXX_VISIBILITY(default) {
103 _GLIBCXX_BEGIN_NAMESPACE_VERSION
108 #if defined(__clang__)
109 # if __has_feature(address_sanitizer)
110 # define FBSTRING_SANITIZE_ADDRESS
112 #elif defined (__GNUC__) && \
113 (((__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)) || (__GNUC__ >= 5)) && \
115 # define FBSTRING_SANITIZE_ADDRESS
118 // When compiling with ASan, always heap-allocate the string even if
119 // it would fit in-situ, so that ASan can detect access to the string
120 // buffer after it has been invalidated (destroyed, resized, etc.).
121 // Note that this flag doesn't remove support for in-situ strings, as
122 // that would break ABI-compatibility and wouldn't allow linking code
123 // compiled with this flag with code compiled without.
124 #ifdef FBSTRING_SANITIZE_ADDRESS
125 # define FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
128 namespace fbstring_detail {
130 template <class InIt, class OutIt>
133 typename std::iterator_traits<InIt>::difference_type n,
135 for (; n != 0; --n, ++b, ++d) {
141 template <class Pod, class T>
142 inline void pod_fill(Pod* b, Pod* e, T c) {
143 assert(b && e && b <= e);
144 /*static*/ if (sizeof(T) == 1) {
147 auto const ee = b + ((e - b) & ~7u);
148 for (; b != ee; b += 8) {
159 for (; b != e; ++b) {
166 * Lightly structured memcpy, simplifies copying PODs and introduces
167 * some asserts. Unfortunately using this function may cause
168 * measurable overhead (presumably because it adjusts from a begin/end
169 * convention to a pointer/size convention, so it does some extra
170 * arithmetic even though the caller might have done the inverse
171 * adaptation outside).
174 inline void pod_copy(const Pod* b, const Pod* e, Pod* d) {
176 assert(d >= e || d + (e - b) <= b);
177 memcpy(d, b, (e - b) * sizeof(Pod));
181 * Lightly structured memmove, simplifies copying PODs and introduces
185 inline void pod_move(const Pod* b, const Pod* e, Pod* d) {
187 memmove(d, b, (e - b) * sizeof(*b));
190 } // namespace fbstring_detail
193 * Defines a special acquisition method for constructing fbstring
194 * objects. AcquireMallocatedString means that the user passes a
195 * pointer to a malloc-allocated string that the fbstring object will
198 enum class AcquireMallocatedString {};
201 * fbstring_core_model is a mock-up type that defines all required
202 * signatures of a fbstring core. The fbstring class itself uses such
203 * a core object to implement all of the numerous member functions
204 * required by the standard.
206 * If you want to define a new core, copy the definition below and
207 * implement the primitives. Then plug the core into basic_fbstring as
208 * a template argument.
210 template <class Char>
211 class fbstring_core_model {
213 fbstring_core_model();
214 fbstring_core_model(const fbstring_core_model &);
215 ~fbstring_core_model();
216 // Returns a pointer to string's buffer (currently only contiguous
217 // strings are supported). The pointer is guaranteed to be valid
218 // until the next call to a non-const member function.
219 const Char * data() const;
220 // Much like data(), except the string is prepared to support
221 // character-level changes. This call is a signal for
222 // e.g. reference-counted implementation to fork the data. The
223 // pointer is guaranteed to be valid until the next call to a
224 // non-const member function.
225 Char * mutable_data();
226 // Returns a pointer to string's buffer and guarantees that a
227 // readable '\0' lies right after the buffer. The pointer is
228 // guaranteed to be valid until the next call to a non-const member
230 const Char * c_str() const;
231 // Shrinks the string by delta characters. Asserts that delta <=
233 void shrink(size_t delta);
234 // Expands the string by delta characters (i.e. after this call
235 // size() will report the old size() plus delta) but without
236 // initializing the expanded region. The expanded region is
237 // zero-terminated. Returns a pointer to the memory to be
238 // initialized (the beginning of the expanded portion). The caller
239 // is expected to fill the expanded area appropriately.
240 // If expGrowth is true, exponential growth is guaranteed.
241 // It is not guaranteed not to reallocate even if size() + delta <
242 // capacity(), so all references to the buffer are invalidated.
243 Char* expand_noinit(size_t delta, bool expGrowth);
244 // Expands the string by one character and sets the last character
246 void push_back(Char c);
247 // Returns the string's size.
249 // Returns the string's capacity, i.e. maximum size that the string
250 // can grow to without reallocation. Note that for reference counted
251 // strings that's technically a lie - even assigning characters
252 // within the existing size would cause a reallocation.
253 size_t capacity() const;
254 // Returns true if the data underlying the string is actually shared
255 // across multiple strings (in a refcounted fashion).
256 bool isShared() const;
257 // Makes sure that at least minCapacity characters are available for
258 // the string without reallocation. For reference-counted strings,
259 // it should fork the data even if minCapacity < size().
260 void reserve(size_t minCapacity);
263 fbstring_core_model& operator=(const fbstring_core_model &);
268 * This is the core of the string. The code should work on 32- and
269 * 64-bit and both big- and little-endianan architectures with any
272 * The storage is selected as follows (assuming we store one-byte
273 * characters on a 64-bit machine): (a) "small" strings between 0 and
274 * 23 chars are stored in-situ without allocation (the rightmost byte
275 * stores the size); (b) "medium" strings from 24 through 254 chars
276 * are stored in malloc-allocated memory that is copied eagerly; (c)
277 * "large" strings of 255 chars and above are stored in a similar
278 * structure as medium arrays, except that the string is
279 * reference-counted and copied lazily. the reference count is
280 * allocated right before the character array.
282 * The discriminator between these three strategies sits in two
283 * bits of the rightmost char of the storage. If neither is set, then the
284 * string is small (and its length sits in the lower-order bits on
285 * little-endian or the high-order bits on big-endian of that
286 * rightmost character). If the MSb is set, the string is medium width.
287 * If the second MSb is set, then the string is large. On little-endian,
288 * these 2 bits are the 2 MSbs of MediumLarge::capacity_, while on
289 * big-endian, these 2 bits are the 2 LSbs. This keeps both little-endian
290 * and big-endian fbstring_core equivalent with merely different ops used
291 * to extract capacity/category.
293 template <class Char> class fbstring_core {
295 // It's MSVC, so we just have to guess ... and allow an override
297 # ifdef FOLLY_ENDIAN_BE
298 static constexpr auto kIsLittleEndian = false;
300 static constexpr auto kIsLittleEndian = true;
303 static constexpr auto kIsLittleEndian =
304 __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__;
307 fbstring_core() noexcept { reset(); }
309 fbstring_core(const fbstring_core & rhs) {
310 assert(&rhs != this);
311 // Simplest case first: small strings are bitblitted
312 if (rhs.category() == Category::isSmall) {
313 static_assert(offsetof(MediumLarge, data_) == 0,
314 "fbstring layout failure");
315 static_assert(offsetof(MediumLarge, size_) == sizeof(ml_.data_),
316 "fbstring layout failure");
317 static_assert(offsetof(MediumLarge, capacity_) == 2 * sizeof(ml_.data_),
318 "fbstring layout failure");
319 // Just write the whole thing, don't look at details. In
320 // particular we need to copy capacity anyway because we want
321 // to set the size (don't forget that the last character,
322 // which stores a short string's length, is shared with the
323 // ml_.capacity field).
325 assert(category() == Category::isSmall && this->size() == rhs.size());
326 } else if (rhs.category() == Category::isLarge) {
327 // Large strings are just refcounted
329 RefCounted::incrementRefs(ml_.data_);
330 assert(category() == Category::isLarge && size() == rhs.size());
332 // Medium strings are copied eagerly. Don't forget to allocate
333 // one extra Char for the null terminator.
334 auto const allocSize =
335 goodMallocSize((1 + rhs.ml_.size_) * sizeof(Char));
336 ml_.data_ = static_cast<Char*>(checkedMalloc(allocSize));
337 // Also copies terminator.
338 fbstring_detail::pod_copy(rhs.ml_.data_,
339 rhs.ml_.data_ + rhs.ml_.size_ + 1,
341 ml_.size_ = rhs.ml_.size_;
342 ml_.setCapacity(allocSize / sizeof(Char) - 1, Category::isMedium);
343 assert(category() == Category::isMedium);
345 assert(size() == rhs.size());
346 assert(memcmp(data(), rhs.data(), size() * sizeof(Char)) == 0);
349 fbstring_core(fbstring_core&& goner) noexcept {
352 // Clean goner's carcass
356 fbstring_core(const Char *const data, const size_t size) {
358 #ifndef _LIBSTDCXX_FBSTRING
360 assert(this->size() == size);
361 assert(memcmp(this->data(), data, size * sizeof(Char)) == 0);
366 #ifndef FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
367 // Simplest case first: small strings are bitblitted
368 if (size <= maxSmallSize) {
369 // Layout is: Char* data_, size_t size_, size_t capacity_
370 static_assert(sizeof(*this) == sizeof(Char*) + 2 * sizeof(size_t),
371 "fbstring has unexpected size");
372 static_assert(sizeof(Char*) == sizeof(size_t),
373 "fbstring size assumption violation");
374 // sizeof(size_t) must be a power of 2
375 static_assert((sizeof(size_t) & (sizeof(size_t) - 1)) == 0,
376 "fbstring size assumption violation");
378 // If data is aligned, use fast word-wise copying. Otherwise,
379 // use conservative memcpy.
380 if (reinterpret_cast<size_t>(data) & (sizeof(size_t) - 1)) {
381 fbstring_detail::pod_copy(data, data + size, small_);
383 // Copy one word at a time.
384 // NOTE: This reads bytes which are outside the range of the
385 // string, and makes ASan unhappy, but the small case is
386 // disabled under ASan.
388 const size_t byteSize = size * sizeof(Char);
389 constexpr size_t wordWidth = sizeof(size_t);
390 switch ((byteSize + wordWidth - 1) / wordWidth) { // Number of words.
392 ml_.capacity_ = reinterpret_cast<const size_t*>(data)[2];
394 ml_.size_ = reinterpret_cast<const size_t*>(data)[1];
396 ml_.data_ = *reinterpret_cast<Char**>(const_cast<Char*>(data));
403 #endif // FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
405 if (size <= maxMediumSize) {
406 // Medium strings are allocated normally. Don't forget to
407 // allocate one extra Char for the terminating null.
408 auto const allocSize = goodMallocSize((1 + size) * sizeof(Char));
409 ml_.data_ = static_cast<Char*>(checkedMalloc(allocSize));
410 fbstring_detail::pod_copy(data, data + size, ml_.data_);
412 ml_.setCapacity(allocSize / sizeof(Char) - 1, Category::isMedium);
414 // Large strings are allocated differently
415 size_t effectiveCapacity = size;
416 auto const newRC = RefCounted::create(data, & effectiveCapacity);
417 ml_.data_ = newRC->data_;
419 ml_.setCapacity(effectiveCapacity, Category::isLarge);
421 ml_.data_[size] = '\0';
425 ~fbstring_core() noexcept {
426 auto const c = category();
427 if (c == Category::isSmall) {
430 if (c == Category::isMedium) {
434 RefCounted::decrementRefs(ml_.data_);
437 // Snatches a previously mallocated string. The parameter "size"
438 // is the size of the string, and the parameter "allocatedSize"
439 // is the size of the mallocated block. The string must be
440 // \0-terminated, so allocatedSize >= size + 1 and data[size] == '\0'.
442 // So if you want a 2-character string, pass malloc(3) as "data",
443 // pass 2 as "size", and pass 3 as "allocatedSize".
444 fbstring_core(Char * const data,
446 const size_t allocatedSize,
447 AcquireMallocatedString) {
449 assert(allocatedSize >= size + 1);
450 assert(data[size] == '\0');
451 // Use the medium string storage
454 // Don't forget about null terminator
455 ml_.setCapacity(allocatedSize - 1, Category::isMedium);
457 // No need for the memory
463 // swap below doesn't test whether &rhs == this (and instead
464 // potentially does extra work) on the premise that the rarity of
465 // that situation actually makes the check more expensive than is
467 void swap(fbstring_core & rhs) {
473 // In C++11 data() and c_str() are 100% equivalent.
474 const Char * data() const {
478 Char * mutable_data() {
479 auto const c = category();
480 if (c == Category::isSmall) {
483 assert(c == Category::isMedium || c == Category::isLarge);
484 if (c == Category::isLarge && RefCounted::refs(ml_.data_) > 1) {
486 size_t effectiveCapacity = ml_.capacity();
487 auto const newRC = RefCounted::create(& effectiveCapacity);
488 // If this fails, someone placed the wrong capacity in an
490 assert(effectiveCapacity >= ml_.capacity());
491 // Also copies terminator.
492 fbstring_detail::pod_copy(ml_.data_, ml_.data_ + ml_.size_ + 1,
494 RefCounted::decrementRefs(ml_.data_);
495 ml_.data_ = newRC->data_;
500 const Char * c_str() const {
501 auto const c = category();
502 if (c == Category::isSmall) {
503 assert(small_[smallSize()] == '\0');
506 assert(c == Category::isMedium || c == Category::isLarge);
507 assert(ml_.data_[ml_.size_] == '\0');
511 void shrink(const size_t delta) {
512 if (category() == Category::isSmall) {
513 // Check for underflow
514 assert(delta <= smallSize());
515 setSmallSize(smallSize() - delta);
516 } else if (category() == Category::isMedium ||
517 RefCounted::refs(ml_.data_) == 1) {
518 // Medium strings and unique large strings need no special
520 assert(ml_.size_ >= delta);
522 ml_.data_[ml_.size_] = '\0';
524 assert(ml_.size_ >= delta);
525 // Shared large string, must make unique. This is because of the
526 // durn terminator must be written, which may trample the shared
529 fbstring_core(ml_.data_, ml_.size_ - delta).swap(*this);
531 // No need to write the terminator.
535 void reserve(size_t minCapacity) {
536 if (category() == Category::isLarge) {
538 if (RefCounted::refs(ml_.data_) > 1) {
539 // We must make it unique regardless; in-place reallocation is
540 // useless if the string is shared. In order to not surprise
541 // people, reserve the new block at current capacity or
542 // more. That way, a string's capacity never shrinks after a
544 minCapacity = std::max(minCapacity, ml_.capacity());
545 auto const newRC = RefCounted::create(& minCapacity);
546 // Also copies terminator.
547 fbstring_detail::pod_copy(ml_.data_, ml_.data_ + ml_.size_ + 1,
549 RefCounted::decrementRefs(ml_.data_);
550 ml_.data_ = newRC->data_;
551 ml_.setCapacity(minCapacity, Category::isLarge);
552 // size remains unchanged
554 // String is not shared, so let's try to realloc (if needed)
555 if (minCapacity > ml_.capacity()) {
556 // Asking for more memory
558 RefCounted::reallocate(ml_.data_, ml_.size_,
559 ml_.capacity(), minCapacity);
560 ml_.data_ = newRC->data_;
561 ml_.setCapacity(minCapacity, Category::isLarge);
563 assert(capacity() >= minCapacity);
565 } else if (category() == Category::isMedium) {
566 // String is not shared
567 if (minCapacity <= ml_.capacity()) {
568 return; // nothing to do, there's enough room
570 if (minCapacity <= maxMediumSize) {
571 // Keep the string at medium size. Don't forget to allocate
572 // one extra Char for the terminating null.
573 size_t capacityBytes = goodMallocSize((1 + minCapacity) * sizeof(Char));
574 // Also copies terminator.
575 ml_.data_ = static_cast<Char *>(
578 (ml_.size_ + 1) * sizeof(Char),
579 (ml_.capacity() + 1) * sizeof(Char),
581 ml_.setCapacity(capacityBytes / sizeof(Char) - 1, Category::isMedium);
583 // Conversion from medium to large string
584 fbstring_core nascent;
585 // Will recurse to another branch of this function
586 nascent.reserve(minCapacity);
587 nascent.ml_.size_ = ml_.size_;
588 // Also copies terminator.
589 fbstring_detail::pod_copy(ml_.data_, ml_.data_ + ml_.size_ + 1,
592 assert(capacity() >= minCapacity);
595 assert(category() == Category::isSmall);
596 #ifndef FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
597 if (minCapacity <= maxSmallSize) {
599 // Nothing to do, everything stays put
601 #endif // FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
602 if (minCapacity <= maxMediumSize) {
604 // Don't forget to allocate one extra Char for the terminating null
605 auto const allocSizeBytes =
606 goodMallocSize((1 + minCapacity) * sizeof(Char));
607 auto const pData = static_cast<Char*>(checkedMalloc(allocSizeBytes));
608 auto const size = smallSize();
609 // Also copies terminator.
610 fbstring_detail::pod_copy(small_, small_ + size + 1, pData);
613 ml_.setCapacity(allocSizeBytes / sizeof(Char) - 1, Category::isMedium);
616 auto const newRC = RefCounted::create(& minCapacity);
617 auto const size = smallSize();
618 // Also copies terminator.
619 fbstring_detail::pod_copy(small_, small_ + size + 1, newRC->data_);
620 ml_.data_ = newRC->data_;
622 ml_.setCapacity(minCapacity, Category::isLarge);
623 assert(capacity() >= minCapacity);
626 assert(capacity() >= minCapacity);
629 Char * expand_noinit(const size_t delta, bool expGrowth = false) {
630 // Strategy is simple: make room, then change size
631 assert(capacity() >= size());
633 if (category() == Category::isSmall) {
636 #ifndef FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
637 if (FBSTRING_LIKELY(newSz <= maxSmallSize)) {
641 #endif // FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
642 reserve(expGrowth ? std::max(newSz, 2 * maxSmallSize) : newSz);
646 if (FBSTRING_UNLIKELY(newSz > capacity())) {
647 // ensures not shared
648 reserve(expGrowth ? std::max(newSz, 1 + capacity() * 3 / 2) : newSz);
651 assert(capacity() >= newSz);
652 // Category can't be small - we took care of that above
653 assert(category() == Category::isMedium || category() == Category::isLarge);
655 ml_.data_[newSz] = '\0';
656 assert(size() == newSz);
657 return ml_.data_ + sz;
660 void push_back(Char c) {
661 *expand_noinit(1, /* expGrowth = */ true) = c;
664 size_t size() const {
665 return category() == Category::isSmall ? smallSize() : ml_.size_;
668 size_t capacity() const {
669 switch (category()) {
670 case Category::isSmall:
672 case Category::isLarge:
673 // For large-sized strings, a multi-referenced chunk has no
674 // available capacity. This is because any attempt to append
675 // data would trigger a new allocation.
676 if (RefCounted::refs(ml_.data_) > 1) return ml_.size_;
679 return ml_.capacity();
682 bool isShared() const {
683 return category() == Category::isLarge && RefCounted::refs(ml_.data_) > 1;
688 fbstring_core & operator=(const fbstring_core & rhs);
690 // Equivalent to setSmallSize(0) but a few ns faster in
693 ml_.capacity_ = kIsLittleEndian
694 ? maxSmallSize << (8 * (sizeof(size_t) - sizeof(Char)))
697 assert(category() == Category::isSmall && size() == 0);
701 std::atomic<size_t> refCount_;
704 static RefCounted * fromData(Char * p) {
705 return static_cast<RefCounted*>(
707 static_cast<unsigned char*>(static_cast<void*>(p))
708 - sizeof(refCount_)));
711 static size_t refs(Char * p) {
712 return fromData(p)->refCount_.load(std::memory_order_acquire);
715 static void incrementRefs(Char * p) {
716 fromData(p)->refCount_.fetch_add(1, std::memory_order_acq_rel);
719 static void decrementRefs(Char * p) {
720 auto const dis = fromData(p);
721 size_t oldcnt = dis->refCount_.fetch_sub(1, std::memory_order_acq_rel);
728 static RefCounted * create(size_t * size) {
729 // Don't forget to allocate one extra Char for the terminating
730 // null. In this case, however, one Char is already part of the
732 const size_t allocSize = goodMallocSize(
733 sizeof(RefCounted) + *size * sizeof(Char));
734 auto result = static_cast<RefCounted*>(checkedMalloc(allocSize));
735 result->refCount_.store(1, std::memory_order_release);
736 *size = (allocSize - sizeof(RefCounted)) / sizeof(Char);
740 static RefCounted * create(const Char * data, size_t * size) {
741 const size_t effectiveSize = *size;
742 auto result = create(size);
743 fbstring_detail::pod_copy(data, data + effectiveSize, result->data_);
747 static RefCounted * reallocate(Char *const data,
748 const size_t currentSize,
749 const size_t currentCapacity,
750 const size_t newCapacity) {
751 assert(newCapacity > 0 && newCapacity > currentSize);
752 auto const dis = fromData(data);
753 assert(dis->refCount_.load(std::memory_order_acquire) == 1);
754 // Don't forget to allocate one extra Char for the terminating
755 // null. In this case, however, one Char is already part of the
757 auto result = static_cast<RefCounted*>(
759 sizeof(RefCounted) + currentSize * sizeof(Char),
760 sizeof(RefCounted) + currentCapacity * sizeof(Char),
761 sizeof(RefCounted) + newCapacity * sizeof(Char)));
762 assert(result->refCount_.load(std::memory_order_acquire) == 1);
767 typedef std::conditional<sizeof(size_t) == 4, uint32_t, uint64_t>::type
770 enum class Category : category_type {
772 isMedium = kIsLittleEndian
773 ? sizeof(size_t) == 4 ? 0x80000000 : 0x8000000000000000
775 isLarge = kIsLittleEndian
776 ? sizeof(size_t) == 4 ? 0x40000000 : 0x4000000000000000
780 Category category() const {
781 // works for both big-endian and little-endian
782 return static_cast<Category>(ml_.capacity_ & categoryExtractMask);
790 size_t capacity() const {
791 return kIsLittleEndian
792 ? capacity_ & capacityExtractMask
796 void setCapacity(size_t cap, Category cat) {
797 capacity_ = kIsLittleEndian
798 ? cap | static_cast<category_type>(cat)
799 : (cap << 2) | static_cast<category_type>(cat);
804 Char small_[sizeof(MediumLarge) / sizeof(Char)];
809 lastChar = sizeof(MediumLarge) - 1,
810 maxSmallSize = lastChar / sizeof(Char),
811 maxMediumSize = 254 / sizeof(Char), // coincides with the small
812 // bin size in dlmalloc
813 categoryExtractMask = kIsLittleEndian
814 ? sizeof(size_t) == 4 ? 0xC0000000 : 0xC000000000000000
816 capacityExtractMask = kIsLittleEndian
817 ? ~categoryExtractMask
820 static_assert(!(sizeof(MediumLarge) % sizeof(Char)),
821 "Corrupt memory layout for fbstring.");
823 size_t smallSize() const {
824 assert(category() == Category::isSmall);
825 constexpr auto shift = kIsLittleEndian ? 0 : 2;
826 auto smallShifted = static_cast<size_t>(small_[maxSmallSize]) >> shift;
827 assert(static_cast<size_t>(maxSmallSize) >= smallShifted);
828 return static_cast<size_t>(maxSmallSize) - smallShifted;
831 void setSmallSize(size_t s) {
832 // Warning: this should work with uninitialized strings too,
833 // so don't assume anything about the previous value of
834 // small_[maxSmallSize].
835 assert(s <= maxSmallSize);
836 constexpr auto shift = kIsLittleEndian ? 0 : 2;
837 small_[maxSmallSize] = (maxSmallSize - s) << shift;
839 assert(category() == Category::isSmall && size() == s);
843 #ifndef _LIBSTDCXX_FBSTRING
845 * Dummy fbstring core that uses an actual std::string. This doesn't
846 * make any sense - it's just for testing purposes.
848 template <class Char>
849 class dummy_fbstring_core {
851 dummy_fbstring_core() {
853 dummy_fbstring_core(const dummy_fbstring_core& another)
854 : backend_(another.backend_) {
856 dummy_fbstring_core(const Char * s, size_t n)
859 void swap(dummy_fbstring_core & rhs) {
860 backend_.swap(rhs.backend_);
862 const Char * data() const {
863 return backend_.data();
865 Char * mutable_data() {
866 //assert(!backend_.empty());
867 return &*backend_.begin();
869 void shrink(size_t delta) {
870 assert(delta <= size());
871 backend_.resize(size() - delta);
873 Char * expand_noinit(size_t delta) {
874 auto const sz = size();
875 backend_.resize(size() + delta);
876 return backend_.data() + sz;
878 void push_back(Char c) {
879 backend_.push_back(c);
881 size_t size() const {
882 return backend_.size();
884 size_t capacity() const {
885 return backend_.capacity();
887 bool isShared() const {
890 void reserve(size_t minCapacity) {
891 backend_.reserve(minCapacity);
895 std::basic_string<Char> backend_;
897 #endif // !_LIBSTDCXX_FBSTRING
900 * This is the basic_string replacement. For conformity,
901 * basic_fbstring takes the same template parameters, plus the last
902 * one which is the core.
904 #ifdef _LIBSTDCXX_FBSTRING
905 template <typename E, class T, class A, class Storage>
907 template <typename E,
908 class T = std::char_traits<E>,
909 class A = std::allocator<E>,
910 class Storage = fbstring_core<E> >
912 class basic_fbstring {
916 void (*throw_exc)(const char*),
918 if (!condition) throw_exc(msg);
921 bool isSane() const {
924 empty() == (size() == 0) &&
925 empty() == (begin() == end()) &&
926 size() <= max_size() &&
927 capacity() <= max_size() &&
928 size() <= capacity() &&
929 begin()[size()] == '\0';
933 friend struct Invariant;
936 explicit Invariant(const basic_fbstring& s) : s_(s) {
943 const basic_fbstring& s_;
945 explicit Invariant(const basic_fbstring&) {}
947 Invariant& operator=(const Invariant&);
952 typedef T traits_type;
953 typedef typename traits_type::char_type value_type;
954 typedef A allocator_type;
955 typedef typename A::size_type size_type;
956 typedef typename A::difference_type difference_type;
958 typedef typename A::reference reference;
959 typedef typename A::const_reference const_reference;
960 typedef typename A::pointer pointer;
961 typedef typename A::const_pointer const_pointer;
964 typedef const E* const_iterator;
965 typedef std::reverse_iterator<iterator
966 #ifdef NO_ITERATOR_TRAITS
970 typedef std::reverse_iterator<const_iterator
971 #ifdef NO_ITERATOR_TRAITS
974 > const_reverse_iterator;
976 static const size_type npos; // = size_type(-1)
977 typedef std::true_type IsRelocatable;
980 static void procrustes(size_type& n, size_type nmax) {
981 if (n > nmax) n = nmax;
985 // C++11 21.4.2 construct/copy/destroy
987 // Note: while the following two constructors can be (and previously were)
988 // collapsed into one constructor written this way:
990 // explicit basic_fbstring(const A& a = A()) noexcept { }
992 // This can cause Clang (at least version 3.7) to fail with the error:
993 // "chosen constructor is explicit in copy-initialization ...
994 // in implicit initialization of field '(x)' with omitted initializer"
996 // if used in a struct which is default-initialized. Hence the split into
997 // these two separate constructors.
999 basic_fbstring() noexcept : basic_fbstring(A()) {
1002 explicit basic_fbstring(const A&) noexcept {
1005 basic_fbstring(const basic_fbstring& str)
1006 : store_(str.store_) {
1010 basic_fbstring(basic_fbstring&& goner) noexcept
1011 : store_(std::move(goner.store_)) {
1014 #ifndef _LIBSTDCXX_FBSTRING
1015 // This is defined for compatibility with std::string
1016 /* implicit */ basic_fbstring(const std::string& str)
1017 : store_(str.data(), str.size()) {
1021 basic_fbstring(const basic_fbstring& str,
1024 const A& /* a */ = A()) {
1025 assign(str, pos, n);
1028 /* implicit */ basic_fbstring(const value_type* s, const A& /*a*/ = A())
1030 ? traits_type::length(s)
1031 : (std::__throw_logic_error(
1032 "basic_fbstring: null pointer initializer not valid"),
1036 basic_fbstring(const value_type* s, size_type n, const A& /*a*/ = A())
1040 basic_fbstring(size_type n, value_type c, const A& /*a*/ = A()) {
1041 auto const pData = store_.expand_noinit(n);
1042 fbstring_detail::pod_fill(pData, pData + n, c);
1045 template <class InIt>
1046 basic_fbstring(InIt begin, InIt end,
1047 typename std::enable_if<
1048 !std::is_same<typename std::remove_const<InIt>::type,
1049 value_type*>::value, const A>::type & /*a*/ = A()) {
1053 // Specialization for const char*, const char*
1054 basic_fbstring(const value_type* b, const value_type* e)
1055 : store_(b, e - b) {
1058 // Nonstandard constructor
1059 basic_fbstring(value_type *s, size_type n, size_type c,
1060 AcquireMallocatedString a)
1061 : store_(s, n, c, a) {
1064 // Construction from initialization list
1065 basic_fbstring(std::initializer_list<value_type> il) {
1066 assign(il.begin(), il.end());
1069 ~basic_fbstring() noexcept {
1072 basic_fbstring& operator=(const basic_fbstring& lhs) {
1073 Invariant checker(*this);
1075 if (FBSTRING_UNLIKELY(&lhs == this)) {
1078 auto const oldSize = size();
1079 auto const srcSize = lhs.size();
1080 if (capacity() >= srcSize && !store_.isShared()) {
1081 // great, just copy the contents
1082 if (oldSize < srcSize) {
1083 store_.expand_noinit(srcSize - oldSize);
1085 store_.shrink(oldSize - srcSize);
1087 assert(size() == srcSize);
1088 auto srcData = lhs.data();
1089 fbstring_detail::pod_copy(
1090 srcData, srcData + srcSize, store_.mutable_data());
1092 // need to reallocate, so we may as well create a brand new string
1093 basic_fbstring(lhs).swap(*this);
1099 basic_fbstring& operator=(basic_fbstring&& goner) noexcept {
1100 if (FBSTRING_UNLIKELY(&goner == this)) {
1101 // Compatibility with std::basic_string<>,
1102 // C++11 21.4.2 [string.cons] / 23 requires self-move-assignment support.
1105 // No need of this anymore
1106 this->~basic_fbstring();
1107 // Move the goner into this
1108 new(&store_) fbstring_core<E>(std::move(goner.store_));
1112 #ifndef _LIBSTDCXX_FBSTRING
1113 // Compatibility with std::string
1114 basic_fbstring & operator=(const std::string & rhs) {
1115 return assign(rhs.data(), rhs.size());
1118 // Compatibility with std::string
1119 std::string toStdString() const {
1120 return std::string(data(), size());
1123 // A lot of code in fbcode still uses this method, so keep it here for now.
1124 const basic_fbstring& toStdString() const {
1129 basic_fbstring& operator=(const value_type* s) {
1133 basic_fbstring& operator=(value_type c) {
1134 Invariant checker(*this);
1137 store_.expand_noinit(1);
1138 } else if (store_.isShared()) {
1139 basic_fbstring(1, c).swap(*this);
1142 store_.shrink(size() - 1);
1148 basic_fbstring& operator=(std::initializer_list<value_type> il) {
1149 return assign(il.begin(), il.end());
1152 // C++11 21.4.3 iterators:
1153 iterator begin() { return store_.mutable_data(); }
1155 const_iterator begin() const { return store_.data(); }
1157 const_iterator cbegin() const { return begin(); }
1160 return store_.mutable_data() + store_.size();
1163 const_iterator end() const {
1164 return store_.data() + store_.size();
1167 const_iterator cend() const { return end(); }
1169 reverse_iterator rbegin() {
1170 return reverse_iterator(end());
1173 const_reverse_iterator rbegin() const {
1174 return const_reverse_iterator(end());
1177 const_reverse_iterator crbegin() const { return rbegin(); }
1179 reverse_iterator rend() {
1180 return reverse_iterator(begin());
1183 const_reverse_iterator rend() const {
1184 return const_reverse_iterator(begin());
1187 const_reverse_iterator crend() const { return rend(); }
1190 // C++11 21.4.5, element access:
1191 const value_type& front() const { return *begin(); }
1192 const value_type& back() const {
1194 // Should be begin()[size() - 1], but that branches twice
1195 return *(end() - 1);
1197 value_type& front() { return *begin(); }
1198 value_type& back() {
1200 // Should be begin()[size() - 1], but that branches twice
1201 return *(end() - 1);
1208 // C++11 21.4.4 capacity:
1209 size_type size() const { return store_.size(); }
1211 size_type length() const { return size(); }
1213 size_type max_size() const {
1214 return std::numeric_limits<size_type>::max();
1217 void resize(const size_type n, const value_type c = value_type()) {
1218 Invariant checker(*this);
1220 auto size = this->size();
1222 store_.shrink(size - n);
1224 auto const delta = n - size;
1225 auto pData = store_.expand_noinit(delta);
1226 fbstring_detail::pod_fill(pData, pData + delta, c);
1228 assert(this->size() == n);
1231 size_type capacity() const { return store_.capacity(); }
1233 void reserve(size_type res_arg = 0) {
1234 enforce(res_arg <= max_size(), std::__throw_length_error, "");
1235 store_.reserve(res_arg);
1238 void shrink_to_fit() {
1239 // Shrink only if slack memory is sufficiently large
1240 if (capacity() < size() * 3 / 2) {
1243 basic_fbstring(cbegin(), cend()).swap(*this);
1246 void clear() { resize(0); }
1248 bool empty() const { return size() == 0; }
1250 // C++11 21.4.5 element access:
1251 const_reference operator[](size_type pos) const {
1252 return *(begin() + pos);
1255 reference operator[](size_type pos) {
1256 return *(begin() + pos);
1259 const_reference at(size_type n) const {
1260 enforce(n <= size(), std::__throw_out_of_range, "");
1264 reference at(size_type n) {
1265 enforce(n < size(), std::__throw_out_of_range, "");
1269 // C++11 21.4.6 modifiers:
1270 basic_fbstring& operator+=(const basic_fbstring& str) {
1274 basic_fbstring& operator+=(const value_type* s) {
1278 basic_fbstring& operator+=(const value_type c) {
1283 basic_fbstring& operator+=(std::initializer_list<value_type> il) {
1288 basic_fbstring& append(const basic_fbstring& str) {
1290 auto desiredSize = size() + str.size();
1292 append(str.data(), str.size());
1293 assert(size() == desiredSize);
1297 basic_fbstring& append(const basic_fbstring& str, const size_type pos,
1299 const size_type sz = str.size();
1300 enforce(pos <= sz, std::__throw_out_of_range, "");
1301 procrustes(n, sz - pos);
1302 return append(str.data() + pos, n);
1305 basic_fbstring& append(const value_type* s, size_type n) {
1306 Invariant checker(*this);
1308 if (FBSTRING_UNLIKELY(!n)) {
1309 // Unlikely but must be done
1312 auto const oldSize = size();
1313 auto const oldData = data();
1314 // Check for aliasing (rare). We could use "<=" here but in theory
1315 // those do not work for pointers unless the pointers point to
1316 // elements in the same array. For that reason we use
1317 // std::less_equal, which is guaranteed to offer a total order
1318 // over pointers. See discussion at http://goo.gl/Cy2ya for more
1320 std::less_equal<const value_type*> le;
1321 if (FBSTRING_UNLIKELY(le(oldData, s) && !le(oldData + oldSize, s))) {
1322 assert(le(s + n, oldData + oldSize));
1323 const size_type offset = s - oldData;
1324 store_.reserve(oldSize + n);
1325 // Restore the source
1326 s = data() + offset;
1329 fbstring_detail::pod_copy(
1330 s, s + n, store_.expand_noinit(n, /* expGrowth = */ true));
1331 assert(size() == oldSize + n);
1335 basic_fbstring& append(const value_type* s) {
1336 return append(s, traits_type::length(s));
1339 basic_fbstring& append(size_type n, value_type c) {
1340 resize(size() + n, c);
1344 template<class InputIterator>
1345 basic_fbstring& append(InputIterator first, InputIterator last) {
1346 insert(end(), first, last);
1350 basic_fbstring& append(std::initializer_list<value_type> il) {
1351 return append(il.begin(), il.end());
1354 void push_back(const value_type c) { // primitive
1355 store_.push_back(c);
1358 basic_fbstring& assign(const basic_fbstring& str) {
1359 if (&str == this) return *this;
1360 return assign(str.data(), str.size());
1363 basic_fbstring& assign(basic_fbstring&& str) {
1364 return *this = std::move(str);
1367 basic_fbstring& assign(const basic_fbstring& str, const size_type pos,
1369 const size_type sz = str.size();
1370 enforce(pos <= sz, std::__throw_out_of_range, "");
1371 procrustes(n, sz - pos);
1372 return assign(str.data() + pos, n);
1375 basic_fbstring& assign(const value_type* s, const size_type n) {
1376 Invariant checker(*this);
1378 // s can alias this, we need to use pod_move.
1380 fbstring_detail::pod_move(s, s + n, store_.mutable_data());
1382 assert(size() == n);
1384 const value_type *const s2 = s + size();
1385 fbstring_detail::pod_move(s, s2, store_.mutable_data());
1386 append(s2, n - size());
1387 assert(size() == n);
1389 assert(size() == n);
1393 basic_fbstring& assign(const value_type* s) {
1394 return assign(s, traits_type::length(s));
1397 basic_fbstring& assign(std::initializer_list<value_type> il) {
1398 return assign(il.begin(), il.end());
1401 template <class ItOrLength, class ItOrChar>
1402 basic_fbstring& assign(ItOrLength first_or_n, ItOrChar last_or_c) {
1403 return replace(begin(), end(), first_or_n, last_or_c);
1406 basic_fbstring& insert(size_type pos1, const basic_fbstring& str) {
1407 return insert(pos1, str.data(), str.size());
1410 basic_fbstring& insert(size_type pos1, const basic_fbstring& str,
1411 size_type pos2, size_type n) {
1412 enforce(pos2 <= str.length(), std::__throw_out_of_range, "");
1413 procrustes(n, str.length() - pos2);
1414 return insert(pos1, str.data() + pos2, n);
1417 basic_fbstring& insert(size_type pos, const value_type* s, size_type n) {
1418 enforce(pos <= length(), std::__throw_out_of_range, "");
1419 insert(begin() + pos, s, s + n);
1423 basic_fbstring& insert(size_type pos, const value_type* s) {
1424 return insert(pos, s, traits_type::length(s));
1427 basic_fbstring& insert(size_type pos, size_type n, value_type c) {
1428 enforce(pos <= length(), std::__throw_out_of_range, "");
1429 insert(begin() + pos, n, c);
1433 iterator insert(const_iterator p, const value_type c) {
1434 const size_type pos = p - begin();
1436 return begin() + pos;
1439 #ifndef _LIBSTDCXX_FBSTRING
1441 typedef std::basic_istream<value_type, traits_type> istream_type;
1444 friend inline istream_type& getline(istream_type& is,
1445 basic_fbstring& str,
1447 Invariant checker(str);
1452 size_t avail = str.capacity() - size;
1453 // fbstring has 1 byte extra capacity for the null terminator,
1454 // and getline null-terminates the read string.
1455 is.getline(str.store_.expand_noinit(avail), avail + 1, delim);
1456 size += is.gcount();
1458 if (is.bad() || is.eof() || !is.fail()) {
1459 // Done by either failure, end of file, or normal read.
1460 if (!is.bad() && !is.eof()) {
1461 --size; // gcount() also accounts for the delimiter.
1467 assert(size == str.size());
1468 assert(size == str.capacity());
1469 // Start at minimum allocation 63 + terminator = 64.
1470 str.reserve(std::max<size_t>(63, 3 * size / 2));
1471 // Clear the error so we can continue reading.
1477 friend inline istream_type& getline(istream_type& is, basic_fbstring& str) {
1478 return getline(is, str, '\n');
1483 template <int i> class Selector {};
1485 iterator insertImplDiscr(const_iterator p,
1486 size_type n, value_type c, Selector<1>) {
1487 Invariant checker(*this);
1489 auto const pos = p - begin();
1490 assert(p >= begin() && p <= end());
1491 if (capacity() - size() < n) {
1492 const size_type sz = p - begin();
1493 reserve(size() + n);
1496 const iterator oldEnd = end();
1497 if (n < size_type(oldEnd - p)) {
1498 append(oldEnd - n, oldEnd);
1499 // Also copies terminator.
1500 fbstring_detail::pod_move(&*p, &*oldEnd - n + 1, begin() + pos + n);
1501 std::fill(begin() + pos, begin() + pos + n, c);
1503 append(n - (end() - p), c);
1504 append(iterator(p), oldEnd);
1505 std::fill(iterator(p), oldEnd, c);
1507 return begin() + pos;
1510 template<class InputIter>
1511 iterator insertImplDiscr(const_iterator i,
1512 InputIter b, InputIter e, Selector<0>) {
1513 return insertImpl(i, b, e,
1514 typename std::iterator_traits<InputIter>::iterator_category());
1517 template <class FwdIterator>
1518 iterator insertImpl(const_iterator i,
1521 std::forward_iterator_tag) {
1522 Invariant checker(*this);
1524 const size_type pos = i - begin();
1525 auto n = std::distance(s1, s2);
1527 assert(pos <= size());
1529 auto oldSize = size();
1530 store_.expand_noinit(n, /* expGrowth = */ true);
1532 fbstring_detail::pod_move(b + pos, b + oldSize, b + pos + n);
1533 std::copy(s1, s2, b + pos);
1538 template <class InputIterator>
1539 iterator insertImpl(const_iterator i,
1540 InputIterator b, InputIterator e,
1541 std::input_iterator_tag) {
1542 const auto pos = i - begin();
1543 basic_fbstring temp(begin(), i);
1544 for (; b != e; ++b) {
1547 temp.append(i, cend());
1549 return begin() + pos;
1553 template <class ItOrLength, class ItOrChar>
1554 iterator insert(const_iterator p, ItOrLength first_or_n, ItOrChar last_or_c) {
1555 Selector<std::numeric_limits<ItOrLength>::is_specialized> sel;
1556 return insertImplDiscr(p, first_or_n, last_or_c, sel);
1559 iterator insert(const_iterator p, std::initializer_list<value_type> il) {
1560 return insert(p, il.begin(), il.end());
1563 basic_fbstring& erase(size_type pos = 0, size_type n = npos) {
1564 Invariant checker(*this);
1566 enforce(pos <= length(), std::__throw_out_of_range, "");
1567 procrustes(n, length() - pos);
1568 std::copy(begin() + pos + n, end(), begin() + pos);
1569 resize(length() - n);
1573 iterator erase(iterator position) {
1574 const size_type pos(position - begin());
1575 enforce(pos <= size(), std::__throw_out_of_range, "");
1577 return begin() + pos;
1580 iterator erase(iterator first, iterator last) {
1581 const size_type pos(first - begin());
1582 erase(pos, last - first);
1583 return begin() + pos;
1586 // Replaces at most n1 chars of *this, starting with pos1 with the
1588 basic_fbstring& replace(size_type pos1, size_type n1,
1589 const basic_fbstring& str) {
1590 return replace(pos1, n1, str.data(), str.size());
1593 // Replaces at most n1 chars of *this, starting with pos1,
1594 // with at most n2 chars of str starting with pos2
1595 basic_fbstring& replace(size_type pos1, size_type n1,
1596 const basic_fbstring& str,
1597 size_type pos2, size_type n2) {
1598 enforce(pos2 <= str.length(), std::__throw_out_of_range, "");
1599 return replace(pos1, n1, str.data() + pos2,
1600 std::min(n2, str.size() - pos2));
1603 // Replaces at most n1 chars of *this, starting with pos, with chars from s
1604 basic_fbstring& replace(size_type pos, size_type n1, const value_type* s) {
1605 return replace(pos, n1, s, traits_type::length(s));
1608 // Replaces at most n1 chars of *this, starting with pos, with n2
1611 // consolidated with
1613 // Replaces at most n1 chars of *this, starting with pos, with at
1614 // most n2 chars of str. str must have at least n2 chars.
1615 template <class StrOrLength, class NumOrChar>
1616 basic_fbstring& replace(size_type pos, size_type n1,
1617 StrOrLength s_or_n2, NumOrChar n_or_c) {
1618 Invariant checker(*this);
1620 enforce(pos <= size(), std::__throw_out_of_range, "");
1621 procrustes(n1, length() - pos);
1622 const iterator b = begin() + pos;
1623 return replace(b, b + n1, s_or_n2, n_or_c);
1626 basic_fbstring& replace(iterator i1, iterator i2, const basic_fbstring& str) {
1627 return replace(i1, i2, str.data(), str.length());
1630 basic_fbstring& replace(iterator i1, iterator i2, const value_type* s) {
1631 return replace(i1, i2, s, traits_type::length(s));
1635 basic_fbstring& replaceImplDiscr(iterator i1, iterator i2,
1636 const value_type* s, size_type n,
1639 assert(begin() <= i1 && i1 <= end());
1640 assert(begin() <= i2 && i2 <= end());
1641 return replace(i1, i2, s, s + n);
1644 basic_fbstring& replaceImplDiscr(iterator i1, iterator i2,
1645 size_type n2, value_type c, Selector<1>) {
1646 const size_type n1 = i2 - i1;
1648 std::fill(i1, i1 + n2, c);
1651 std::fill(i1, i2, c);
1652 insert(i2, n2 - n1, c);
1658 template <class InputIter>
1659 basic_fbstring& replaceImplDiscr(iterator i1, iterator i2,
1660 InputIter b, InputIter e,
1662 replaceImpl(i1, i2, b, e,
1663 typename std::iterator_traits<InputIter>::iterator_category());
1668 template <class FwdIterator>
1669 bool replaceAliased(iterator /* i1 */,
1671 FwdIterator /* s1 */,
1672 FwdIterator /* s2 */,
1677 template <class FwdIterator>
1678 bool replaceAliased(iterator i1, iterator i2,
1679 FwdIterator s1, FwdIterator s2, std::true_type) {
1680 static const std::less_equal<const value_type*> le =
1681 std::less_equal<const value_type*>();
1682 const bool aliased = le(&*begin(), &*s1) && le(&*s1, &*end());
1686 // Aliased replace, copy to new string
1687 basic_fbstring temp;
1688 temp.reserve(size() - (i2 - i1) + std::distance(s1, s2));
1689 temp.append(begin(), i1).append(s1, s2).append(i2, end());
1694 template <class FwdIterator>
1695 void replaceImpl(iterator i1, iterator i2,
1696 FwdIterator s1, FwdIterator s2, std::forward_iterator_tag) {
1697 Invariant checker(*this);
1699 // Handle aliased replace
1700 if (replaceAliased(i1, i2, s1, s2,
1701 std::integral_constant<bool,
1702 std::is_same<FwdIterator, iterator>::value ||
1703 std::is_same<FwdIterator, const_iterator>::value>())) {
1707 auto const n1 = i2 - i1;
1709 auto const n2 = std::distance(s1, s2);
1714 std::copy(s1, s2, i1);
1718 fbstring_detail::copy_n(s1, n1, i1);
1719 std::advance(s1, n1);
1725 template <class InputIterator>
1726 void replaceImpl(iterator i1, iterator i2,
1727 InputIterator b, InputIterator e, std::input_iterator_tag) {
1728 basic_fbstring temp(begin(), i1);
1729 temp.append(b, e).append(i2, end());
1734 template <class T1, class T2>
1735 basic_fbstring& replace(iterator i1, iterator i2,
1736 T1 first_or_n_or_s, T2 last_or_c_or_n) {
1738 num1 = std::numeric_limits<T1>::is_specialized,
1739 num2 = std::numeric_limits<T2>::is_specialized;
1740 return replaceImplDiscr(
1741 i1, i2, first_or_n_or_s, last_or_c_or_n,
1742 Selector<num1 ? (num2 ? 1 : -1) : (num2 ? 2 : 0)>());
1745 size_type copy(value_type* s, size_type n, size_type pos = 0) const {
1746 enforce(pos <= size(), std::__throw_out_of_range, "");
1747 procrustes(n, size() - pos);
1749 fbstring_detail::pod_copy(
1756 void swap(basic_fbstring& rhs) {
1757 store_.swap(rhs.store_);
1760 const value_type* c_str() const {
1761 return store_.c_str();
1764 const value_type* data() const { return c_str(); }
1766 allocator_type get_allocator() const {
1767 return allocator_type();
1770 size_type find(const basic_fbstring& str, size_type pos = 0) const {
1771 return find(str.data(), pos, str.length());
1774 size_type find(const value_type* needle, const size_type pos,
1775 const size_type nsize) const {
1776 if (!nsize) return pos;
1777 auto const size = this->size();
1778 // nsize + pos can overflow (eg pos == npos), guard against that by checking
1779 // that nsize + pos does not wrap around.
1780 if (nsize + pos > size || nsize + pos < pos) return npos;
1781 // Don't use std::search, use a Boyer-Moore-like trick by comparing
1782 // the last characters first
1783 auto const haystack = data();
1784 auto const nsize_1 = nsize - 1;
1785 auto const lastNeedle = needle[nsize_1];
1787 // Boyer-Moore skip value for the last char in the needle. Zero is
1788 // not a valid value; skip will be computed the first time it's
1792 const E * i = haystack + pos;
1793 auto iEnd = haystack + size - nsize_1;
1796 // Boyer-Moore: match the last element in the needle
1797 while (i[nsize_1] != lastNeedle) {
1803 // Here we know that the last char matches
1804 // Continue in pedestrian mode
1805 for (size_t j = 0; ; ) {
1807 if (i[j] != needle[j]) {
1808 // Not found, we can skip
1809 // Compute the skip value lazily
1812 while (skip <= nsize_1 && needle[nsize_1 - skip] != lastNeedle) {
1819 // Check if done searching
1822 return i - haystack;
1829 size_type find(const value_type* s, size_type pos = 0) const {
1830 return find(s, pos, traits_type::length(s));
1833 size_type find (value_type c, size_type pos = 0) const {
1834 return find(&c, pos, 1);
1837 size_type rfind(const basic_fbstring& str, size_type pos = npos) const {
1838 return rfind(str.data(), pos, str.length());
1841 size_type rfind(const value_type* s, size_type pos, size_type n) const {
1842 if (n > length()) return npos;
1843 pos = std::min(pos, length() - n);
1844 if (n == 0) return pos;
1846 const_iterator i(begin() + pos);
1848 if (traits_type::eq(*i, *s)
1849 && traits_type::compare(&*i, s, n) == 0) {
1852 if (i == begin()) break;
1857 size_type rfind(const value_type* s, size_type pos = npos) const {
1858 return rfind(s, pos, traits_type::length(s));
1861 size_type rfind(value_type c, size_type pos = npos) const {
1862 return rfind(&c, pos, 1);
1865 size_type find_first_of(const basic_fbstring& str, size_type pos = 0) const {
1866 return find_first_of(str.data(), pos, str.length());
1869 size_type find_first_of(const value_type* s,
1870 size_type pos, size_type n) const {
1871 if (pos > length() || n == 0) return npos;
1872 const_iterator i(begin() + pos),
1874 for (; i != finish; ++i) {
1875 if (traits_type::find(s, n, *i) != 0) {
1882 size_type find_first_of(const value_type* s, size_type pos = 0) const {
1883 return find_first_of(s, pos, traits_type::length(s));
1886 size_type find_first_of(value_type c, size_type pos = 0) const {
1887 return find_first_of(&c, pos, 1);
1890 size_type find_last_of (const basic_fbstring& str,
1891 size_type pos = npos) const {
1892 return find_last_of(str.data(), pos, str.length());
1895 size_type find_last_of (const value_type* s, size_type pos,
1896 size_type n) const {
1897 if (!empty() && n > 0) {
1898 pos = std::min(pos, length() - 1);
1899 const_iterator i(begin() + pos);
1901 if (traits_type::find(s, n, *i) != 0) {
1904 if (i == begin()) break;
1910 size_type find_last_of (const value_type* s,
1911 size_type pos = npos) const {
1912 return find_last_of(s, pos, traits_type::length(s));
1915 size_type find_last_of (value_type c, size_type pos = npos) const {
1916 return find_last_of(&c, pos, 1);
1919 size_type find_first_not_of(const basic_fbstring& str,
1920 size_type pos = 0) const {
1921 return find_first_not_of(str.data(), pos, str.size());
1924 size_type find_first_not_of(const value_type* s, size_type pos,
1925 size_type n) const {
1926 if (pos < length()) {
1930 for (; i != finish; ++i) {
1931 if (traits_type::find(s, n, *i) == 0) {
1939 size_type find_first_not_of(const value_type* s,
1940 size_type pos = 0) const {
1941 return find_first_not_of(s, pos, traits_type::length(s));
1944 size_type find_first_not_of(value_type c, size_type pos = 0) const {
1945 return find_first_not_of(&c, pos, 1);
1948 size_type find_last_not_of(const basic_fbstring& str,
1949 size_type pos = npos) const {
1950 return find_last_not_of(str.data(), pos, str.length());
1953 size_type find_last_not_of(const value_type* s, size_type pos,
1954 size_type n) const {
1955 if (!this->empty()) {
1956 pos = std::min(pos, size() - 1);
1957 const_iterator i(begin() + pos);
1959 if (traits_type::find(s, n, *i) == 0) {
1962 if (i == begin()) break;
1968 size_type find_last_not_of(const value_type* s,
1969 size_type pos = npos) const {
1970 return find_last_not_of(s, pos, traits_type::length(s));
1973 size_type find_last_not_of (value_type c, size_type pos = npos) const {
1974 return find_last_not_of(&c, pos, 1);
1977 basic_fbstring substr(size_type pos = 0, size_type n = npos) const& {
1978 enforce(pos <= size(), std::__throw_out_of_range, "");
1979 return basic_fbstring(data() + pos, std::min(n, size() - pos));
1982 basic_fbstring substr(size_type pos = 0, size_type n = npos) && {
1983 enforce(pos <= size(), std::__throw_out_of_range, "");
1985 if (n < size()) resize(n);
1986 return std::move(*this);
1989 int compare(const basic_fbstring& str) const {
1990 // FIX due to Goncalo N M de Carvalho July 18, 2005
1991 return compare(0, size(), str);
1994 int compare(size_type pos1, size_type n1,
1995 const basic_fbstring& str) const {
1996 return compare(pos1, n1, str.data(), str.size());
1999 int compare(size_type pos1, size_type n1,
2000 const value_type* s) const {
2001 return compare(pos1, n1, s, traits_type::length(s));
2004 int compare(size_type pos1, size_type n1,
2005 const value_type* s, size_type n2) const {
2006 enforce(pos1 <= size(), std::__throw_out_of_range, "");
2007 procrustes(n1, size() - pos1);
2008 // The line below fixed by Jean-Francois Bastien, 04-23-2007. Thanks!
2009 const int r = traits_type::compare(pos1 + data(), s, std::min(n1, n2));
2010 return r != 0 ? r : n1 > n2 ? 1 : n1 < n2 ? -1 : 0;
2013 int compare(size_type pos1, size_type n1,
2014 const basic_fbstring& str,
2015 size_type pos2, size_type n2) const {
2016 enforce(pos2 <= str.size(), std::__throw_out_of_range, "");
2017 return compare(pos1, n1, str.data() + pos2,
2018 std::min(n2, str.size() - pos2));
2021 // Code from Jean-Francois Bastien (03/26/2007)
2022 int compare(const value_type* s) const {
2023 // Could forward to compare(0, size(), s, traits_type::length(s))
2024 // but that does two extra checks
2025 const size_type n1(size()), n2(traits_type::length(s));
2026 const int r = traits_type::compare(data(), s, std::min(n1, n2));
2027 return r != 0 ? r : n1 > n2 ? 1 : n1 < n2 ? -1 : 0;
2035 // non-member functions
2037 template <typename E, class T, class A, class S>
2039 basic_fbstring<E, T, A, S> operator+(const basic_fbstring<E, T, A, S>& lhs,
2040 const basic_fbstring<E, T, A, S>& rhs) {
2042 basic_fbstring<E, T, A, S> result;
2043 result.reserve(lhs.size() + rhs.size());
2044 result.append(lhs).append(rhs);
2045 return std::move(result);
2049 template <typename E, class T, class A, class S>
2051 basic_fbstring<E, T, A, S> operator+(basic_fbstring<E, T, A, S>&& lhs,
2052 const basic_fbstring<E, T, A, S>& rhs) {
2053 return std::move(lhs.append(rhs));
2057 template <typename E, class T, class A, class S>
2059 basic_fbstring<E, T, A, S> operator+(const basic_fbstring<E, T, A, S>& lhs,
2060 basic_fbstring<E, T, A, S>&& rhs) {
2061 if (rhs.capacity() >= lhs.size() + rhs.size()) {
2062 // Good, at least we don't need to reallocate
2063 return std::move(rhs.insert(0, lhs));
2065 // Meh, no go. Forward to operator+(const&, const&).
2066 auto const& rhsC = rhs;
2071 template <typename E, class T, class A, class S>
2073 basic_fbstring<E, T, A, S> operator+(basic_fbstring<E, T, A, S>&& lhs,
2074 basic_fbstring<E, T, A, S>&& rhs) {
2075 return std::move(lhs.append(rhs));
2079 template <typename E, class T, class A, class S>
2081 basic_fbstring<E, T, A, S> operator+(
2083 const basic_fbstring<E, T, A, S>& rhs) {
2085 basic_fbstring<E, T, A, S> result;
2086 const auto len = basic_fbstring<E, T, A, S>::traits_type::length(lhs);
2087 result.reserve(len + rhs.size());
2088 result.append(lhs, len).append(rhs);
2093 template <typename E, class T, class A, class S>
2095 basic_fbstring<E, T, A, S> operator+(
2097 basic_fbstring<E, T, A, S>&& rhs) {
2099 const auto len = basic_fbstring<E, T, A, S>::traits_type::length(lhs);
2100 if (rhs.capacity() >= len + rhs.size()) {
2101 // Good, at least we don't need to reallocate
2102 rhs.insert(rhs.begin(), lhs, lhs + len);
2105 // Meh, no go. Do it by hand since we have len already.
2106 basic_fbstring<E, T, A, S> result;
2107 result.reserve(len + rhs.size());
2108 result.append(lhs, len).append(rhs);
2113 template <typename E, class T, class A, class S>
2115 basic_fbstring<E, T, A, S> operator+(
2117 const basic_fbstring<E, T, A, S>& rhs) {
2119 basic_fbstring<E, T, A, S> result;
2120 result.reserve(1 + rhs.size());
2121 result.push_back(lhs);
2127 template <typename E, class T, class A, class S>
2129 basic_fbstring<E, T, A, S> operator+(
2131 basic_fbstring<E, T, A, S>&& rhs) {
2133 if (rhs.capacity() > rhs.size()) {
2134 // Good, at least we don't need to reallocate
2135 rhs.insert(rhs.begin(), lhs);
2138 // Meh, no go. Forward to operator+(E, const&).
2139 auto const& rhsC = rhs;
2144 template <typename E, class T, class A, class S>
2146 basic_fbstring<E, T, A, S> operator+(
2147 const basic_fbstring<E, T, A, S>& lhs,
2150 typedef typename basic_fbstring<E, T, A, S>::size_type size_type;
2151 typedef typename basic_fbstring<E, T, A, S>::traits_type traits_type;
2153 basic_fbstring<E, T, A, S> result;
2154 const size_type len = traits_type::length(rhs);
2155 result.reserve(lhs.size() + len);
2156 result.append(lhs).append(rhs, len);
2160 // C++11 21.4.8.1/10
2161 template <typename E, class T, class A, class S>
2163 basic_fbstring<E, T, A, S> operator+(
2164 basic_fbstring<E, T, A, S>&& lhs,
2167 return std::move(lhs += rhs);
2170 // C++11 21.4.8.1/11
2171 template <typename E, class T, class A, class S>
2173 basic_fbstring<E, T, A, S> operator+(
2174 const basic_fbstring<E, T, A, S>& lhs,
2177 basic_fbstring<E, T, A, S> result;
2178 result.reserve(lhs.size() + 1);
2180 result.push_back(rhs);
2184 // C++11 21.4.8.1/12
2185 template <typename E, class T, class A, class S>
2187 basic_fbstring<E, T, A, S> operator+(
2188 basic_fbstring<E, T, A, S>&& lhs,
2191 return std::move(lhs += rhs);
2194 template <typename E, class T, class A, class S>
2196 bool operator==(const basic_fbstring<E, T, A, S>& lhs,
2197 const basic_fbstring<E, T, A, S>& rhs) {
2198 return lhs.size() == rhs.size() && lhs.compare(rhs) == 0; }
2200 template <typename E, class T, class A, class S>
2202 bool operator==(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2203 const basic_fbstring<E, T, A, S>& rhs) {
2204 return rhs == lhs; }
2206 template <typename E, class T, class A, class S>
2208 bool operator==(const basic_fbstring<E, T, A, S>& lhs,
2209 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2210 return lhs.compare(rhs) == 0; }
2212 template <typename E, class T, class A, class S>
2214 bool operator!=(const basic_fbstring<E, T, A, S>& lhs,
2215 const basic_fbstring<E, T, A, S>& rhs) {
2216 return !(lhs == rhs); }
2218 template <typename E, class T, class A, class S>
2220 bool operator!=(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2221 const basic_fbstring<E, T, A, S>& rhs) {
2222 return !(lhs == rhs); }
2224 template <typename E, class T, class A, class S>
2226 bool operator!=(const basic_fbstring<E, T, A, S>& lhs,
2227 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2228 return !(lhs == rhs); }
2230 template <typename E, class T, class A, class S>
2232 bool operator<(const basic_fbstring<E, T, A, S>& lhs,
2233 const basic_fbstring<E, T, A, S>& rhs) {
2234 return lhs.compare(rhs) < 0; }
2236 template <typename E, class T, class A, class S>
2238 bool operator<(const basic_fbstring<E, T, A, S>& lhs,
2239 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2240 return lhs.compare(rhs) < 0; }
2242 template <typename E, class T, class A, class S>
2244 bool operator<(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2245 const basic_fbstring<E, T, A, S>& rhs) {
2246 return rhs.compare(lhs) > 0; }
2248 template <typename E, class T, class A, class S>
2250 bool operator>(const basic_fbstring<E, T, A, S>& lhs,
2251 const basic_fbstring<E, T, A, S>& rhs) {
2254 template <typename E, class T, class A, class S>
2256 bool operator>(const basic_fbstring<E, T, A, S>& lhs,
2257 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2260 template <typename E, class T, class A, class S>
2262 bool operator>(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2263 const basic_fbstring<E, T, A, S>& rhs) {
2266 template <typename E, class T, class A, class S>
2268 bool operator<=(const basic_fbstring<E, T, A, S>& lhs,
2269 const basic_fbstring<E, T, A, S>& rhs) {
2270 return !(rhs < lhs); }
2272 template <typename E, class T, class A, class S>
2274 bool operator<=(const basic_fbstring<E, T, A, S>& lhs,
2275 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2276 return !(rhs < lhs); }
2278 template <typename E, class T, class A, class S>
2280 bool operator<=(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2281 const basic_fbstring<E, T, A, S>& rhs) {
2282 return !(rhs < lhs); }
2284 template <typename E, class T, class A, class S>
2286 bool operator>=(const basic_fbstring<E, T, A, S>& lhs,
2287 const basic_fbstring<E, T, A, S>& rhs) {
2288 return !(lhs < rhs); }
2290 template <typename E, class T, class A, class S>
2292 bool operator>=(const basic_fbstring<E, T, A, S>& lhs,
2293 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2294 return !(lhs < rhs); }
2296 template <typename E, class T, class A, class S>
2298 bool operator>=(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2299 const basic_fbstring<E, T, A, S>& rhs) {
2300 return !(lhs < rhs);
2304 template <typename E, class T, class A, class S>
2305 void swap(basic_fbstring<E, T, A, S>& lhs, basic_fbstring<E, T, A, S>& rhs) {
2309 // TODO: make this faster.
2310 template <typename E, class T, class A, class S>
2313 typename basic_fbstring<E, T, A, S>::value_type,
2314 typename basic_fbstring<E, T, A, S>::traits_type>&
2316 std::basic_istream<typename basic_fbstring<E, T, A, S>::value_type,
2317 typename basic_fbstring<E, T, A, S>::traits_type>& is,
2318 basic_fbstring<E, T, A, S>& str) {
2319 typename std::basic_istream<E, T>::sentry sentry(is);
2320 typedef std::basic_istream<typename basic_fbstring<E, T, A, S>::value_type,
2321 typename basic_fbstring<E, T, A, S>::traits_type>
2323 typedef typename __istream_type::ios_base __ios_base;
2324 size_t extracted = 0;
2325 auto err = __ios_base::goodbit;
2327 auto n = is.width();
2332 for (auto got = is.rdbuf()->sgetc(); extracted != size_t(n); ++extracted) {
2333 if (got == T::eof()) {
2334 err |= __ios_base::eofbit;
2338 if (isspace(got)) break;
2340 got = is.rdbuf()->snextc();
2344 err |= __ios_base::failbit;
2352 template <typename E, class T, class A, class S>
2354 std::basic_ostream<typename basic_fbstring<E, T, A, S>::value_type,
2355 typename basic_fbstring<E, T, A, S>::traits_type>&
2357 std::basic_ostream<typename basic_fbstring<E, T, A, S>::value_type,
2358 typename basic_fbstring<E, T, A, S>::traits_type>& os,
2359 const basic_fbstring<E, T, A, S>& str) {
2361 typename std::basic_ostream<
2362 typename basic_fbstring<E, T, A, S>::value_type,
2363 typename basic_fbstring<E, T, A, S>::traits_type>::sentry __s(os);
2365 typedef std::ostreambuf_iterator<
2366 typename basic_fbstring<E, T, A, S>::value_type,
2367 typename basic_fbstring<E, T, A, S>::traits_type> _Ip;
2368 size_t __len = str.size();
2370 (os.flags() & std::ios_base::adjustfield) == std::ios_base::left;
2371 if (__pad_and_output(_Ip(os),
2373 __left ? str.data() + __len : str.data(),
2376 os.fill()).failed()) {
2377 os.setstate(std::ios_base::badbit | std::ios_base::failbit);
2380 #elif defined(_MSC_VER)
2381 // MSVC doesn't define __ostream_insert
2382 os.write(str.data(), str.size());
2384 std::__ostream_insert(os, str.data(), str.size());
2389 template <typename E1, class T, class A, class S>
2390 const typename basic_fbstring<E1, T, A, S>::size_type
2391 basic_fbstring<E1, T, A, S>::npos =
2392 static_cast<typename basic_fbstring<E1, T, A, S>::size_type>(-1);
2394 #ifndef _LIBSTDCXX_FBSTRING
2395 // basic_string compatibility routines
2397 template <typename E, class T, class A, class S>
2399 bool operator==(const basic_fbstring<E, T, A, S>& lhs,
2400 const std::string& rhs) {
2401 return lhs.compare(0, lhs.size(), rhs.data(), rhs.size()) == 0;
2404 template <typename E, class T, class A, class S>
2406 bool operator==(const std::string& lhs,
2407 const basic_fbstring<E, T, A, S>& rhs) {
2411 template <typename E, class T, class A, class S>
2413 bool operator!=(const basic_fbstring<E, T, A, S>& lhs,
2414 const std::string& rhs) {
2415 return !(lhs == rhs);
2418 template <typename E, class T, class A, class S>
2420 bool operator!=(const std::string& lhs,
2421 const basic_fbstring<E, T, A, S>& rhs) {
2422 return !(lhs == rhs);
2425 #if !defined(_LIBSTDCXX_FBSTRING)
2426 typedef basic_fbstring<char> fbstring;
2429 // fbstring is relocatable
2430 template <class T, class R, class A, class S>
2431 FOLLY_ASSUME_RELOCATABLE(basic_fbstring<T, R, A, S>);
2434 _GLIBCXX_END_NAMESPACE_VERSION
2437 } // namespace folly
2439 #ifndef _LIBSTDCXX_FBSTRING
2441 // Hash functions to make fbstring usable with e.g. hash_map
2443 // Handle interaction with different C++ standard libraries, which
2444 // expect these types to be in different namespaces.
2446 #define FOLLY_FBSTRING_HASH1(T) \
2448 struct hash< ::folly::basic_fbstring<T> > { \
2449 size_t operator()(const ::folly::fbstring& s) const { \
2450 return ::folly::hash::fnv32_buf(s.data(), s.size()); \
2454 // The C++11 standard says that these four are defined
2455 #define FOLLY_FBSTRING_HASH \
2456 FOLLY_FBSTRING_HASH1(char) \
2457 FOLLY_FBSTRING_HASH1(char16_t) \
2458 FOLLY_FBSTRING_HASH1(char32_t) \
2459 FOLLY_FBSTRING_HASH1(wchar_t)
2467 #if FOLLY_HAVE_DEPRECATED_ASSOC
2468 #if defined(_GLIBCXX_SYMVER) && !defined(__BIONIC__)
2469 namespace __gnu_cxx {
2473 } // namespace __gnu_cxx
2474 #endif // _GLIBCXX_SYMVER && !__BIONIC__
2475 #endif // FOLLY_HAVE_DEPRECATED_ASSOC
2477 #undef FOLLY_FBSTRING_HASH
2478 #undef FOLLY_FBSTRING_HASH1
2480 #endif // _LIBSTDCXX_FBSTRING
2482 #pragma GCC diagnostic pop
2484 #undef FBSTRING_DISABLE_SMALL_STRING_OPTIMIZATION
2485 #undef FBSTRING_SANITIZE_ADDRESS
2487 #undef FBSTRING_LIKELY
2488 #undef FBSTRING_UNLIKELY
2490 #ifdef FOLLY_DEFINED_NDEBUG_FOR_FBSTRING
2492 #undef FOLLY_DEFINED_NDEBUG_FOR_FBSTRING
2493 #endif // FOLLY_DEFINED_NDEBUG_FOR_FBSTRING