2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 // @author: Andrei Alexandrescu (aalexandre)
26 #include <type_traits>
28 // This file appears in two locations: inside fbcode and in the
29 // libstdc++ source code (when embedding fbstring as std::string).
30 // To aid in this schizophrenic use, _LIBSTDCXX_FBSTRING is defined in
31 // libstdc++'s c++config.h, to gate use inside fbcode v. libstdc++.
32 #ifdef _LIBSTDCXX_FBSTRING
34 #pragma GCC system_header
36 #include "basic_fbstring_malloc.h"
38 // When used as std::string replacement always disable assertions.
39 #define FBSTRING_ASSERT(expr) /* empty */
41 #else // !_LIBSTDCXX_FBSTRING
43 #include <folly/Portability.h>
45 // libc++ doesn't provide this header, nor does msvc
46 #ifdef FOLLY_HAVE_BITS_CXXCONFIG_H
47 #include <bits/c++config.h>
56 #include <folly/Hash.h>
57 #include <folly/Malloc.h>
58 #include <folly/Traits.h>
60 #if FOLLY_HAVE_DEPRECATED_ASSOC
61 #ifdef _GLIBCXX_SYMVER
62 #include <ext/hash_set>
63 #include <ext/hash_map>
67 // When used in folly, assertions are not disabled.
68 #define FBSTRING_ASSERT(expr) assert(expr)
72 // We defined these here rather than including Likely.h to avoid
73 // redefinition errors when fbstring is imported into libstdc++.
74 #if defined(__GNUC__) && __GNUC__ >= 4
75 #define FBSTRING_LIKELY(x) (__builtin_expect((x), 1))
76 #define FBSTRING_UNLIKELY(x) (__builtin_expect((x), 0))
78 #define FBSTRING_LIKELY(x) (x)
79 #define FBSTRING_UNLIKELY(x) (x)
82 #pragma GCC diagnostic push
83 // Ignore shadowing warnings within this file, so includers can use -Wshadow.
84 #pragma GCC diagnostic ignored "-Wshadow"
85 // GCC 4.9 has a false positive in setSmallSize (probably
86 // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59124), disable
87 // compile-time array bound checking.
88 #pragma GCC diagnostic ignored "-Warray-bounds"
90 // FBString cannot use throw when replacing std::string, though it may still
93 #define throw FOLLY_FBSTRING_MAY_NOT_USE_THROW
95 #ifdef _LIBSTDCXX_FBSTRING
96 namespace std _GLIBCXX_VISIBILITY(default) {
97 _GLIBCXX_BEGIN_NAMESPACE_VERSION
102 #if defined(__clang__)
103 # if __has_feature(address_sanitizer)
104 # define FBSTRING_SANITIZE_ADDRESS
106 #elif defined (__GNUC__) && \
107 (((__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)) || (__GNUC__ >= 5)) && \
109 # define FBSTRING_SANITIZE_ADDRESS
112 // When compiling with ASan, always heap-allocate the string even if
113 // it would fit in-situ, so that ASan can detect access to the string
114 // buffer after it has been invalidated (destroyed, resized, etc.).
115 // Note that this flag doesn't remove support for in-situ strings, as
116 // that would break ABI-compatibility and wouldn't allow linking code
117 // compiled with this flag with code compiled without.
118 #ifdef FBSTRING_SANITIZE_ADDRESS
119 # define FBSTRING_DISABLE_SSO true
121 # define FBSTRING_DISABLE_SSO false
124 namespace fbstring_detail {
126 template <class InIt, class OutIt>
127 inline std::pair<InIt, OutIt> copy_n(
129 typename std::iterator_traits<InIt>::difference_type n,
131 for (; n != 0; --n, ++b, ++d) {
134 return std::make_pair(b, d);
137 template <class Pod, class T>
138 inline void podFill(Pod* b, Pod* e, T c) {
139 FBSTRING_ASSERT(b && e && b <= e);
140 constexpr auto kUseMemset = sizeof(T) == 1;
141 /* static */ if (kUseMemset) {
142 memset(b, c, size_t(e - b));
144 auto const ee = b + ((e - b) & ~7u);
145 for (; b != ee; b += 8) {
156 for (; b != e; ++b) {
163 * Lightly structured memcpy, simplifies copying PODs and introduces
164 * some asserts. Unfortunately using this function may cause
165 * measurable overhead (presumably because it adjusts from a begin/end
166 * convention to a pointer/size convention, so it does some extra
167 * arithmetic even though the caller might have done the inverse
168 * adaptation outside).
171 inline void podCopy(const Pod* b, const Pod* e, Pod* d) {
172 FBSTRING_ASSERT(b != nullptr);
173 FBSTRING_ASSERT(e != nullptr);
174 FBSTRING_ASSERT(d != nullptr);
175 FBSTRING_ASSERT(e >= b);
176 FBSTRING_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 podMove(const Pod* b, const Pod* e, Pod* d) {
186 FBSTRING_ASSERT(e >= b);
187 memmove(d, b, (e - b) * sizeof(*b));
191 #if defined(__GNUC__) // Clang also defines __GNUC__
192 # define FBSTRING_ALWAYS_INLINE inline __attribute__((__always_inline__))
193 #elif defined(_MSC_VER)
194 # define FBSTRING_ALWAYS_INLINE __forceinline
196 # define FBSTRING_ALWAYS_INLINE inline
199 [[noreturn]] FBSTRING_ALWAYS_INLINE void assume_unreachable() {
200 #if defined(__GNUC__) // Clang also defines __GNUC__
201 __builtin_unreachable();
202 #elif defined(_MSC_VER)
205 // Well, it's better than nothing.
210 } // namespace fbstring_detail
213 * Defines a special acquisition method for constructing fbstring
214 * objects. AcquireMallocatedString means that the user passes a
215 * pointer to a malloc-allocated string that the fbstring object will
218 enum class AcquireMallocatedString {};
221 * fbstring_core_model is a mock-up type that defines all required
222 * signatures of a fbstring core. The fbstring class itself uses such
223 * a core object to implement all of the numerous member functions
224 * required by the standard.
226 * If you want to define a new core, copy the definition below and
227 * implement the primitives. Then plug the core into basic_fbstring as
228 * a template argument.
230 template <class Char>
231 class fbstring_core_model {
233 fbstring_core_model();
234 fbstring_core_model(const fbstring_core_model &);
235 ~fbstring_core_model();
236 // Returns a pointer to string's buffer (currently only contiguous
237 // strings are supported). The pointer is guaranteed to be valid
238 // until the next call to a non-const member function.
239 const Char * data() const;
240 // Much like data(), except the string is prepared to support
241 // character-level changes. This call is a signal for
242 // e.g. reference-counted implementation to fork the data. The
243 // pointer is guaranteed to be valid until the next call to a
244 // non-const member function.
246 // Returns a pointer to string's buffer and guarantees that a
247 // readable '\0' lies right after the buffer. The pointer is
248 // guaranteed to be valid until the next call to a non-const member
250 const Char * c_str() const;
251 // Shrinks the string by delta characters. Asserts that delta <=
253 void shrink(size_t delta);
254 // Expands the string by delta characters (i.e. after this call
255 // size() will report the old size() plus delta) but without
256 // initializing the expanded region. The expanded region is
257 // zero-terminated. Returns a pointer to the memory to be
258 // initialized (the beginning of the expanded portion). The caller
259 // is expected to fill the expanded area appropriately.
260 // If expGrowth is true, exponential growth is guaranteed.
261 // It is not guaranteed not to reallocate even if size() + delta <
262 // capacity(), so all references to the buffer are invalidated.
263 Char* expandNoinit(size_t delta, bool expGrowth);
264 // Expands the string by one character and sets the last character
266 void push_back(Char c);
267 // Returns the string's size.
269 // Returns the string's capacity, i.e. maximum size that the string
270 // can grow to without reallocation. Note that for reference counted
271 // strings that's technically a lie - even assigning characters
272 // within the existing size would cause a reallocation.
273 size_t capacity() const;
274 // Returns true if the data underlying the string is actually shared
275 // across multiple strings (in a refcounted fashion).
276 bool isShared() const;
277 // Makes sure that at least minCapacity characters are available for
278 // the string without reallocation. For reference-counted strings,
279 // it should fork the data even if minCapacity < size().
280 void reserve(size_t minCapacity);
283 fbstring_core_model& operator=(const fbstring_core_model &);
288 * This is the core of the string. The code should work on 32- and
289 * 64-bit and both big- and little-endianan architectures with any
292 * The storage is selected as follows (assuming we store one-byte
293 * characters on a 64-bit machine): (a) "small" strings between 0 and
294 * 23 chars are stored in-situ without allocation (the rightmost byte
295 * stores the size); (b) "medium" strings from 24 through 254 chars
296 * are stored in malloc-allocated memory that is copied eagerly; (c)
297 * "large" strings of 255 chars and above are stored in a similar
298 * structure as medium arrays, except that the string is
299 * reference-counted and copied lazily. the reference count is
300 * allocated right before the character array.
302 * The discriminator between these three strategies sits in two
303 * bits of the rightmost char of the storage. If neither is set, then the
304 * string is small (and its length sits in the lower-order bits on
305 * little-endian or the high-order bits on big-endian of that
306 * rightmost character). If the MSb is set, the string is medium width.
307 * If the second MSb is set, then the string is large. On little-endian,
308 * these 2 bits are the 2 MSbs of MediumLarge::capacity_, while on
309 * big-endian, these 2 bits are the 2 LSbs. This keeps both little-endian
310 * and big-endian fbstring_core equivalent with merely different ops used
311 * to extract capacity/category.
313 template <class Char> class fbstring_core {
315 // It's MSVC, so we just have to guess ... and allow an override
317 # ifdef FOLLY_ENDIAN_BE
318 static constexpr auto kIsLittleEndian = false;
320 static constexpr auto kIsLittleEndian = true;
323 static constexpr auto kIsLittleEndian =
324 __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__;
327 fbstring_core() noexcept { reset(); }
329 fbstring_core(const fbstring_core & rhs) {
330 FBSTRING_ASSERT(&rhs != this);
331 switch (rhs.category()) {
332 case Category::isSmall:
335 case Category::isMedium:
338 case Category::isLarge:
342 fbstring_detail::assume_unreachable();
344 FBSTRING_ASSERT(size() == rhs.size());
345 FBSTRING_ASSERT(memcmp(data(), rhs.data(), size() * sizeof(Char)) == 0);
348 fbstring_core(fbstring_core&& goner) noexcept {
351 // Clean goner's carcass
355 fbstring_core(const Char *const data,
357 bool disableSSO = FBSTRING_DISABLE_SSO) {
358 if (!disableSSO && size <= maxSmallSize) {
359 initSmall(data, size);
360 } else if (size <= maxMediumSize) {
361 initMedium(data, size);
363 initLarge(data, size);
365 FBSTRING_ASSERT(this->size() == size);
367 size == 0 || memcmp(this->data(), data, size * sizeof(Char)) == 0);
370 ~fbstring_core() noexcept {
371 if (category() == Category::isSmall) {
374 destroyMediumLarge();
377 // Snatches a previously mallocated string. The parameter "size"
378 // is the size of the string, and the parameter "allocatedSize"
379 // is the size of the mallocated block. The string must be
380 // \0-terminated, so allocatedSize >= size + 1 and data[size] == '\0'.
382 // So if you want a 2-character string, pass malloc(3) as "data",
383 // pass 2 as "size", and pass 3 as "allocatedSize".
384 fbstring_core(Char * const data,
386 const size_t allocatedSize,
387 AcquireMallocatedString) {
389 FBSTRING_ASSERT(allocatedSize >= size + 1);
390 FBSTRING_ASSERT(data[size] == '\0');
391 // Use the medium string storage
394 // Don't forget about null terminator
395 ml_.setCapacity(allocatedSize - 1, Category::isMedium);
397 // No need for the memory
403 // swap below doesn't test whether &rhs == this (and instead
404 // potentially does extra work) on the premise that the rarity of
405 // that situation actually makes the check more expensive than is
407 void swap(fbstring_core & rhs) {
413 // In C++11 data() and c_str() are 100% equivalent.
414 const Char * data() const {
418 Char* mutableData() {
419 switch (category()) {
420 case Category::isSmall:
422 case Category::isMedium:
424 case Category::isLarge:
425 return mutableDataLarge();
427 fbstring_detail::assume_unreachable();
430 const Char* c_str() const {
431 const Char* ptr = ml_.data_;
432 // With this syntax, GCC and Clang generate a CMOV instead of a branch.
433 ptr = (category() == Category::isSmall) ? small_ : ptr;
437 void shrink(const size_t delta) {
438 if (category() == Category::isSmall) {
440 } else if (category() == Category::isMedium ||
441 RefCounted::refs(ml_.data_) == 1) {
448 FOLLY_MALLOC_NOINLINE
449 void reserve(size_t minCapacity, bool disableSSO = FBSTRING_DISABLE_SSO) {
450 switch (category()) {
451 case Category::isSmall:
452 reserveSmall(minCapacity, disableSSO);
454 case Category::isMedium:
455 reserveMedium(minCapacity);
457 case Category::isLarge:
458 reserveLarge(minCapacity);
461 fbstring_detail::assume_unreachable();
463 FBSTRING_ASSERT(capacity() >= minCapacity);
468 bool expGrowth = false,
469 bool disableSSO = FBSTRING_DISABLE_SSO);
471 void push_back(Char c) {
472 *expandNoinit(1, /* expGrowth = */ true) = c;
475 size_t size() const {
476 size_t ret = ml_.size_;
477 /* static */ if (kIsLittleEndian) {
478 // We can save a couple instructions, because the category is
479 // small iff the last char, as unsigned, is <= maxSmallSize.
480 typedef typename std::make_unsigned<Char>::type UChar;
481 auto maybeSmallSize = size_t(maxSmallSize) -
482 size_t(static_cast<UChar>(small_[maxSmallSize]));
483 // With this syntax, GCC and Clang generate a CMOV instead of a branch.
484 ret = (static_cast<ssize_t>(maybeSmallSize) >= 0) ? maybeSmallSize : ret;
486 ret = (category() == Category::isSmall) ? smallSize() : ret;
491 size_t capacity() const {
492 switch (category()) {
493 case Category::isSmall:
495 case Category::isLarge:
496 // For large-sized strings, a multi-referenced chunk has no
497 // available capacity. This is because any attempt to append
498 // data would trigger a new allocation.
499 if (RefCounted::refs(ml_.data_) > 1) {
504 return ml_.capacity();
507 bool isShared() const {
508 return category() == Category::isLarge && RefCounted::refs(ml_.data_) > 1;
513 fbstring_core & operator=(const fbstring_core & rhs);
519 FOLLY_MALLOC_NOINLINE void destroyMediumLarge() noexcept {
520 auto const c = category();
521 FBSTRING_ASSERT(c != Category::isSmall);
522 if (c == Category::isMedium) {
525 RefCounted::decrementRefs(ml_.data_);
530 std::atomic<size_t> refCount_;
533 constexpr static size_t getDataOffset() {
534 return offsetof(RefCounted, data_);
537 static RefCounted * fromData(Char * p) {
538 return static_cast<RefCounted*>(static_cast<void*>(
539 static_cast<unsigned char*>(static_cast<void*>(p)) -
543 static size_t refs(Char * p) {
544 return fromData(p)->refCount_.load(std::memory_order_acquire);
547 static void incrementRefs(Char * p) {
548 fromData(p)->refCount_.fetch_add(1, std::memory_order_acq_rel);
551 static void decrementRefs(Char * p) {
552 auto const dis = fromData(p);
553 size_t oldcnt = dis->refCount_.fetch_sub(1, std::memory_order_acq_rel);
554 FBSTRING_ASSERT(oldcnt > 0);
560 static RefCounted * create(size_t * size) {
561 const size_t allocSize =
562 goodMallocSize(getDataOffset() + (*size + 1) * sizeof(Char));
563 auto result = static_cast<RefCounted*>(checkedMalloc(allocSize));
564 result->refCount_.store(1, std::memory_order_release);
565 *size = (allocSize - getDataOffset()) / sizeof(Char) - 1;
569 static RefCounted * create(const Char * data, size_t * size) {
570 const size_t effectiveSize = *size;
571 auto result = create(size);
572 if (FBSTRING_LIKELY(effectiveSize > 0)) {
573 fbstring_detail::podCopy(data, data + effectiveSize, result->data_);
578 static RefCounted * reallocate(Char *const data,
579 const size_t currentSize,
580 const size_t currentCapacity,
581 size_t * newCapacity) {
582 FBSTRING_ASSERT(*newCapacity > 0 && *newCapacity > currentSize);
583 const size_t allocNewCapacity =
584 goodMallocSize(getDataOffset() + (*newCapacity + 1) * sizeof(Char));
585 auto const dis = fromData(data);
586 FBSTRING_ASSERT(dis->refCount_.load(std::memory_order_acquire) == 1);
587 auto result = static_cast<RefCounted*>(smartRealloc(
589 getDataOffset() + (currentSize + 1) * sizeof(Char),
590 getDataOffset() + (currentCapacity + 1) * sizeof(Char),
592 FBSTRING_ASSERT(result->refCount_.load(std::memory_order_acquire) == 1);
593 *newCapacity = (allocNewCapacity - getDataOffset()) / sizeof(Char) - 1;
598 typedef uint8_t category_type;
600 enum class Category : category_type {
602 isMedium = kIsLittleEndian ? 0x80 : 0x2,
603 isLarge = kIsLittleEndian ? 0x40 : 0x1,
606 Category category() const {
607 // works for both big-endian and little-endian
608 return static_cast<Category>(bytes_[lastChar] & categoryExtractMask);
616 size_t capacity() const {
617 return kIsLittleEndian
618 ? capacity_ & capacityExtractMask
622 void setCapacity(size_t cap, Category cat) {
623 capacity_ = kIsLittleEndian
624 ? cap | (static_cast<size_t>(cat) << kCategoryShift)
625 : (cap << 2) | static_cast<size_t>(cat);
630 uint8_t bytes_[sizeof(MediumLarge)]; // For accessing the last byte.
631 Char small_[sizeof(MediumLarge) / sizeof(Char)];
635 constexpr static size_t lastChar = sizeof(MediumLarge) - 1;
636 constexpr static size_t maxSmallSize = lastChar / sizeof(Char);
637 constexpr static size_t maxMediumSize = 254 / sizeof(Char);
638 constexpr static uint8_t categoryExtractMask = kIsLittleEndian ? 0xC0 : 0x3;
639 constexpr static size_t kCategoryShift = (sizeof(size_t) - 1) * 8;
640 constexpr static size_t capacityExtractMask = kIsLittleEndian
641 ? ~(size_t(categoryExtractMask) << kCategoryShift)
644 static_assert(!(sizeof(MediumLarge) % sizeof(Char)),
645 "Corrupt memory layout for fbstring.");
647 size_t smallSize() const {
648 FBSTRING_ASSERT(category() == Category::isSmall);
649 constexpr auto shift = kIsLittleEndian ? 0 : 2;
650 auto smallShifted = static_cast<size_t>(small_[maxSmallSize]) >> shift;
651 FBSTRING_ASSERT(static_cast<size_t>(maxSmallSize) >= smallShifted);
652 return static_cast<size_t>(maxSmallSize) - smallShifted;
655 void setSmallSize(size_t s) {
656 // Warning: this should work with uninitialized strings too,
657 // so don't assume anything about the previous value of
658 // small_[maxSmallSize].
659 FBSTRING_ASSERT(s <= maxSmallSize);
660 constexpr auto shift = kIsLittleEndian ? 0 : 2;
661 small_[maxSmallSize] = char((maxSmallSize - s) << shift);
663 FBSTRING_ASSERT(category() == Category::isSmall && size() == s);
666 void copySmall(const fbstring_core&);
667 void copyMedium(const fbstring_core&);
668 void copyLarge(const fbstring_core&);
670 void initSmall(const Char* data, size_t size);
671 void initMedium(const Char* data, size_t size);
672 void initLarge(const Char* data, size_t size);
674 void reserveSmall(size_t minCapacity, bool disableSSO);
675 void reserveMedium(size_t minCapacity);
676 void reserveLarge(size_t minCapacity);
678 void shrinkSmall(size_t delta);
679 void shrinkMedium(size_t delta);
680 void shrinkLarge(size_t delta);
682 void unshare(size_t minCapacity = 0);
683 Char* mutableDataLarge();
686 template <class Char>
687 inline void fbstring_core<Char>::copySmall(const fbstring_core& rhs) {
688 static_assert(offsetof(MediumLarge, data_) == 0, "fbstring layout failure");
690 offsetof(MediumLarge, size_) == sizeof(ml_.data_),
691 "fbstring layout failure");
693 offsetof(MediumLarge, capacity_) == 2 * sizeof(ml_.data_),
694 "fbstring layout failure");
695 // Just write the whole thing, don't look at details. In
696 // particular we need to copy capacity anyway because we want
697 // to set the size (don't forget that the last character,
698 // which stores a short string's length, is shared with the
699 // ml_.capacity field).
702 category() == Category::isSmall && this->size() == rhs.size());
705 template <class Char>
706 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::copyMedium(
707 const fbstring_core& rhs) {
708 // Medium strings are copied eagerly. Don't forget to allocate
709 // one extra Char for the null terminator.
710 auto const allocSize = goodMallocSize((1 + rhs.ml_.size_) * sizeof(Char));
711 ml_.data_ = static_cast<Char*>(checkedMalloc(allocSize));
712 // Also copies terminator.
713 fbstring_detail::podCopy(
714 rhs.ml_.data_, rhs.ml_.data_ + rhs.ml_.size_ + 1, ml_.data_);
715 ml_.size_ = rhs.ml_.size_;
716 ml_.setCapacity(allocSize / sizeof(Char) - 1, Category::isMedium);
717 FBSTRING_ASSERT(category() == Category::isMedium);
720 template <class Char>
721 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::copyLarge(
722 const fbstring_core& rhs) {
723 // Large strings are just refcounted
725 RefCounted::incrementRefs(ml_.data_);
726 FBSTRING_ASSERT(category() == Category::isLarge && size() == rhs.size());
729 // Small strings are bitblitted
730 template <class Char>
731 inline void fbstring_core<Char>::initSmall(
732 const Char* const data, const size_t size) {
733 // Layout is: Char* data_, size_t size_, size_t capacity_
735 sizeof(*this) == sizeof(Char*) + 2 * sizeof(size_t),
736 "fbstring has unexpected size");
738 sizeof(Char*) == sizeof(size_t), "fbstring size assumption violation");
739 // sizeof(size_t) must be a power of 2
741 (sizeof(size_t) & (sizeof(size_t) - 1)) == 0,
742 "fbstring size assumption violation");
744 // If data is aligned, use fast word-wise copying. Otherwise,
745 // use conservative memcpy.
746 // The word-wise path reads bytes which are outside the range of
747 // the string, and makes ASan unhappy, so we disable it when
748 // compiling with ASan.
749 #ifndef FBSTRING_SANITIZE_ADDRESS
750 if ((reinterpret_cast<size_t>(data) & (sizeof(size_t) - 1)) == 0) {
751 const size_t byteSize = size * sizeof(Char);
752 constexpr size_t wordWidth = sizeof(size_t);
753 switch ((byteSize + wordWidth - 1) / wordWidth) { // Number of words.
755 ml_.capacity_ = reinterpret_cast<const size_t*>(data)[2];
757 ml_.size_ = reinterpret_cast<const size_t*>(data)[1];
759 ml_.data_ = *reinterpret_cast<Char**>(const_cast<Char*>(data));
767 fbstring_detail::podCopy(data, data + size, small_);
773 template <class Char>
774 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::initMedium(
775 const Char* const data, const size_t size) {
776 // Medium strings are allocated normally. Don't forget to
777 // allocate one extra Char for the terminating null.
778 auto const allocSize = goodMallocSize((1 + size) * sizeof(Char));
779 ml_.data_ = static_cast<Char*>(checkedMalloc(allocSize));
780 if (FBSTRING_LIKELY(size > 0)) {
781 fbstring_detail::podCopy(data, data + size, ml_.data_);
784 ml_.setCapacity(allocSize / sizeof(Char) - 1, Category::isMedium);
785 ml_.data_[size] = '\0';
788 template <class Char>
789 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::initLarge(
790 const Char* const data, const size_t size) {
791 // Large strings are allocated differently
792 size_t effectiveCapacity = size;
793 auto const newRC = RefCounted::create(data, &effectiveCapacity);
794 ml_.data_ = newRC->data_;
796 ml_.setCapacity(effectiveCapacity, Category::isLarge);
797 ml_.data_[size] = '\0';
800 template <class Char>
801 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::unshare(
802 size_t minCapacity) {
803 FBSTRING_ASSERT(category() == Category::isLarge);
804 size_t effectiveCapacity = std::max(minCapacity, ml_.capacity());
805 auto const newRC = RefCounted::create(&effectiveCapacity);
806 // If this fails, someone placed the wrong capacity in an
808 FBSTRING_ASSERT(effectiveCapacity >= ml_.capacity());
809 // Also copies terminator.
810 fbstring_detail::podCopy(ml_.data_, ml_.data_ + ml_.size_ + 1, newRC->data_);
811 RefCounted::decrementRefs(ml_.data_);
812 ml_.data_ = newRC->data_;
813 ml_.setCapacity(effectiveCapacity, Category::isLarge);
814 // size_ remains unchanged.
817 template <class Char>
818 inline Char* fbstring_core<Char>::mutableDataLarge() {
819 FBSTRING_ASSERT(category() == Category::isLarge);
820 if (RefCounted::refs(ml_.data_) > 1) { // Ensure unique.
826 template <class Char>
827 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::reserveLarge(
828 size_t minCapacity) {
829 FBSTRING_ASSERT(category() == Category::isLarge);
830 if (RefCounted::refs(ml_.data_) > 1) { // Ensure unique
831 // We must make it unique regardless; in-place reallocation is
832 // useless if the string is shared. In order to not surprise
833 // people, reserve the new block at current capacity or
834 // more. That way, a string's capacity never shrinks after a
836 unshare(minCapacity);
838 // String is not shared, so let's try to realloc (if needed)
839 if (minCapacity > ml_.capacity()) {
840 // Asking for more memory
841 auto const newRC = RefCounted::reallocate(
842 ml_.data_, ml_.size_, ml_.capacity(), &minCapacity);
843 ml_.data_ = newRC->data_;
844 ml_.setCapacity(minCapacity, Category::isLarge);
846 FBSTRING_ASSERT(capacity() >= minCapacity);
850 template <class Char>
851 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::reserveMedium(
852 const size_t minCapacity) {
853 FBSTRING_ASSERT(category() == Category::isMedium);
854 // String is not shared
855 if (minCapacity <= ml_.capacity()) {
856 return; // nothing to do, there's enough room
858 if (minCapacity <= maxMediumSize) {
859 // Keep the string at medium size. Don't forget to allocate
860 // one extra Char for the terminating null.
861 size_t capacityBytes = goodMallocSize((1 + minCapacity) * sizeof(Char));
862 // Also copies terminator.
863 ml_.data_ = static_cast<Char*>(smartRealloc(
865 (ml_.size_ + 1) * sizeof(Char),
866 (ml_.capacity() + 1) * sizeof(Char),
868 ml_.setCapacity(capacityBytes / sizeof(Char) - 1, Category::isMedium);
870 // Conversion from medium to large string
871 fbstring_core nascent;
872 // Will recurse to another branch of this function
873 nascent.reserve(minCapacity);
874 nascent.ml_.size_ = ml_.size_;
875 // Also copies terminator.
876 fbstring_detail::podCopy(
877 ml_.data_, ml_.data_ + ml_.size_ + 1, nascent.ml_.data_);
879 FBSTRING_ASSERT(capacity() >= minCapacity);
883 template <class Char>
884 FOLLY_MALLOC_NOINLINE inline void fbstring_core<Char>::reserveSmall(
885 size_t minCapacity, const bool disableSSO) {
886 FBSTRING_ASSERT(category() == Category::isSmall);
887 if (!disableSSO && minCapacity <= maxSmallSize) {
889 // Nothing to do, everything stays put
890 } else if (minCapacity <= maxMediumSize) {
892 // Don't forget to allocate one extra Char for the terminating null
893 auto const allocSizeBytes =
894 goodMallocSize((1 + minCapacity) * sizeof(Char));
895 auto const pData = static_cast<Char*>(checkedMalloc(allocSizeBytes));
896 auto const size = smallSize();
897 // Also copies terminator.
898 fbstring_detail::podCopy(small_, small_ + size + 1, pData);
901 ml_.setCapacity(allocSizeBytes / sizeof(Char) - 1, Category::isMedium);
904 auto const newRC = RefCounted::create(&minCapacity);
905 auto const size = smallSize();
906 // Also copies terminator.
907 fbstring_detail::podCopy(small_, small_ + size + 1, newRC->data_);
908 ml_.data_ = newRC->data_;
910 ml_.setCapacity(minCapacity, Category::isLarge);
911 FBSTRING_ASSERT(capacity() >= minCapacity);
915 template <class Char>
916 inline Char* fbstring_core<Char>::expandNoinit(
918 bool expGrowth, /* = false */
919 bool disableSSO /* = FBSTRING_DISABLE_SSO */) {
920 // Strategy is simple: make room, then change size
921 FBSTRING_ASSERT(capacity() >= size());
923 if (category() == Category::isSmall) {
926 if (!disableSSO && FBSTRING_LIKELY(newSz <= maxSmallSize)) {
931 expGrowth ? std::max(newSz, 2 * maxSmallSize) : newSz, disableSSO);
935 if (FBSTRING_UNLIKELY(newSz > capacity())) {
936 // ensures not shared
937 reserve(expGrowth ? std::max(newSz, 1 + capacity() * 3 / 2) : newSz);
940 FBSTRING_ASSERT(capacity() >= newSz);
941 // Category can't be small - we took care of that above
943 category() == Category::isMedium || category() == Category::isLarge);
945 ml_.data_[newSz] = '\0';
946 FBSTRING_ASSERT(size() == newSz);
947 return ml_.data_ + sz;
950 template <class Char>
951 inline void fbstring_core<Char>::shrinkSmall(const size_t delta) {
952 // Check for underflow
953 FBSTRING_ASSERT(delta <= smallSize());
954 setSmallSize(smallSize() - delta);
957 template <class Char>
958 inline void fbstring_core<Char>::shrinkMedium(const size_t delta) {
959 // Medium strings and unique large strings need no special
961 FBSTRING_ASSERT(ml_.size_ >= delta);
963 ml_.data_[ml_.size_] = '\0';
966 template <class Char>
967 inline void fbstring_core<Char>::shrinkLarge(const size_t delta) {
968 FBSTRING_ASSERT(ml_.size_ >= delta);
969 // Shared large string, must make unique. This is because of the
970 // durn terminator must be written, which may trample the shared
973 fbstring_core(ml_.data_, ml_.size_ - delta).swap(*this);
975 // No need to write the terminator.
978 #ifndef _LIBSTDCXX_FBSTRING
980 * Dummy fbstring core that uses an actual std::string. This doesn't
981 * make any sense - it's just for testing purposes.
983 template <class Char>
984 class dummy_fbstring_core {
986 dummy_fbstring_core() {
988 dummy_fbstring_core(const dummy_fbstring_core& another)
989 : backend_(another.backend_) {
991 dummy_fbstring_core(const Char * s, size_t n)
994 void swap(dummy_fbstring_core & rhs) {
995 backend_.swap(rhs.backend_);
997 const Char * data() const {
998 return backend_.data();
1000 Char* mutableData() {
1001 return const_cast<Char*>(backend_.data());
1003 void shrink(size_t delta) {
1004 FBSTRING_ASSERT(delta <= size());
1005 backend_.resize(size() - delta);
1007 Char* expandNoinit(size_t delta) {
1008 auto const sz = size();
1009 backend_.resize(size() + delta);
1010 return backend_.data() + sz;
1012 void push_back(Char c) {
1013 backend_.push_back(c);
1015 size_t size() const {
1016 return backend_.size();
1018 size_t capacity() const {
1019 return backend_.capacity();
1021 bool isShared() const {
1024 void reserve(size_t minCapacity) {
1025 backend_.reserve(minCapacity);
1029 std::basic_string<Char> backend_;
1031 #endif // !_LIBSTDCXX_FBSTRING
1034 * This is the basic_string replacement. For conformity,
1035 * basic_fbstring takes the same template parameters, plus the last
1036 * one which is the core.
1038 #ifdef _LIBSTDCXX_FBSTRING
1039 template <typename E, class T, class A, class Storage>
1041 template <typename E,
1042 class T = std::char_traits<E>,
1043 class A = std::allocator<E>,
1044 class Storage = fbstring_core<E> >
1046 class basic_fbstring {
1047 static void enforce(
1049 void (*throw_exc)(const char*),
1056 bool isSane() const {
1059 empty() == (size() == 0) &&
1060 empty() == (begin() == end()) &&
1061 size() <= max_size() &&
1062 capacity() <= max_size() &&
1063 size() <= capacity() &&
1064 begin()[size()] == '\0';
1068 Invariant& operator=(const Invariant&) = delete;
1069 explicit Invariant(const basic_fbstring& s) noexcept : s_(s) {
1070 FBSTRING_ASSERT(s_.isSane());
1072 ~Invariant() noexcept {
1073 FBSTRING_ASSERT(s_.isSane());
1077 const basic_fbstring& s_;
1082 typedef T traits_type;
1083 typedef typename traits_type::char_type value_type;
1084 typedef A allocator_type;
1085 typedef typename A::size_type size_type;
1086 typedef typename A::difference_type difference_type;
1088 typedef typename A::reference reference;
1089 typedef typename A::const_reference const_reference;
1090 typedef typename A::pointer pointer;
1091 typedef typename A::const_pointer const_pointer;
1093 typedef E* iterator;
1094 typedef const E* const_iterator;
1095 typedef std::reverse_iterator<iterator
1096 #ifdef NO_ITERATOR_TRAITS
1100 typedef std::reverse_iterator<const_iterator
1101 #ifdef NO_ITERATOR_TRAITS
1104 > const_reverse_iterator;
1106 static constexpr size_type npos = size_type(-1);
1107 typedef std::true_type IsRelocatable;
1110 static void procrustes(size_type& n, size_type nmax) {
1116 static size_type traitsLength(const value_type* s);
1119 // C++11 21.4.2 construct/copy/destroy
1121 // Note: while the following two constructors can be (and previously were)
1122 // collapsed into one constructor written this way:
1124 // explicit basic_fbstring(const A& a = A()) noexcept { }
1126 // This can cause Clang (at least version 3.7) to fail with the error:
1127 // "chosen constructor is explicit in copy-initialization ...
1128 // in implicit initialization of field '(x)' with omitted initializer"
1130 // if used in a struct which is default-initialized. Hence the split into
1131 // these two separate constructors.
1133 basic_fbstring() noexcept : basic_fbstring(A()) {
1136 explicit basic_fbstring(const A&) noexcept {
1139 basic_fbstring(const basic_fbstring& str)
1140 : store_(str.store_) {
1144 basic_fbstring(basic_fbstring&& goner) noexcept
1145 : store_(std::move(goner.store_)) {
1148 #ifndef _LIBSTDCXX_FBSTRING
1149 // This is defined for compatibility with std::string
1150 /* implicit */ basic_fbstring(const std::string& str)
1151 : store_(str.data(), str.size()) {
1155 basic_fbstring(const basic_fbstring& str,
1158 const A& /* a */ = A()) {
1159 assign(str, pos, n);
1162 FOLLY_MALLOC_NOINLINE
1163 /* implicit */ basic_fbstring(const value_type* s, const A& /*a*/ = A())
1164 : store_(s, traitsLength(s)) {}
1166 FOLLY_MALLOC_NOINLINE
1167 basic_fbstring(const value_type* s, size_type n, const A& /*a*/ = A())
1171 FOLLY_MALLOC_NOINLINE
1172 basic_fbstring(size_type n, value_type c, const A& /*a*/ = A()) {
1173 auto const pData = store_.expandNoinit(n);
1174 fbstring_detail::podFill(pData, pData + n, c);
1177 template <class InIt>
1178 FOLLY_MALLOC_NOINLINE basic_fbstring(
1181 typename std::enable_if<
1182 !std::is_same<InIt, value_type*>::value,
1183 const A>::type& /*a*/ = A()) {
1187 // Specialization for const char*, const char*
1188 FOLLY_MALLOC_NOINLINE
1189 basic_fbstring(const value_type* b, const value_type* e, const A& /*a*/ = A())
1190 : store_(b, size_type(e - b)) {
1193 // Nonstandard constructor
1194 basic_fbstring(value_type *s, size_type n, size_type c,
1195 AcquireMallocatedString a)
1196 : store_(s, n, c, a) {
1199 // Construction from initialization list
1200 FOLLY_MALLOC_NOINLINE
1201 basic_fbstring(std::initializer_list<value_type> il) {
1202 assign(il.begin(), il.end());
1205 ~basic_fbstring() noexcept {}
1207 basic_fbstring& operator=(const basic_fbstring& lhs);
1210 basic_fbstring& operator=(basic_fbstring&& goner) noexcept;
1212 #ifndef _LIBSTDCXX_FBSTRING
1213 // Compatibility with std::string
1214 basic_fbstring & operator=(const std::string & rhs) {
1215 return assign(rhs.data(), rhs.size());
1218 // Compatibility with std::string
1219 std::string toStdString() const {
1220 return std::string(data(), size());
1223 // A lot of code in fbcode still uses this method, so keep it here for now.
1224 const basic_fbstring& toStdString() const {
1229 basic_fbstring& operator=(const value_type* s) {
1233 basic_fbstring& operator=(value_type c);
1235 basic_fbstring& operator=(std::initializer_list<value_type> il) {
1236 return assign(il.begin(), il.end());
1239 // C++11 21.4.3 iterators:
1241 return store_.mutableData();
1244 const_iterator begin() const {
1245 return store_.data();
1248 const_iterator cbegin() const {
1253 return store_.mutableData() + store_.size();
1256 const_iterator end() const {
1257 return store_.data() + store_.size();
1260 const_iterator cend() const { return end(); }
1262 reverse_iterator rbegin() {
1263 return reverse_iterator(end());
1266 const_reverse_iterator rbegin() const {
1267 return const_reverse_iterator(end());
1270 const_reverse_iterator crbegin() const { return rbegin(); }
1272 reverse_iterator rend() {
1273 return reverse_iterator(begin());
1276 const_reverse_iterator rend() const {
1277 return const_reverse_iterator(begin());
1280 const_reverse_iterator crend() const { return rend(); }
1283 // C++11 21.4.5, element access:
1284 const value_type& front() const { return *begin(); }
1285 const value_type& back() const {
1286 FBSTRING_ASSERT(!empty());
1287 // Should be begin()[size() - 1], but that branches twice
1288 return *(end() - 1);
1290 value_type& front() { return *begin(); }
1291 value_type& back() {
1292 FBSTRING_ASSERT(!empty());
1293 // Should be begin()[size() - 1], but that branches twice
1294 return *(end() - 1);
1297 FBSTRING_ASSERT(!empty());
1301 // C++11 21.4.4 capacity:
1302 size_type size() const { return store_.size(); }
1304 size_type length() const { return size(); }
1306 size_type max_size() const {
1307 return std::numeric_limits<size_type>::max();
1310 void resize(size_type n, value_type c = value_type());
1312 size_type capacity() const { return store_.capacity(); }
1314 void reserve(size_type res_arg = 0) {
1315 enforce(res_arg <= max_size(), std::__throw_length_error, "");
1316 store_.reserve(res_arg);
1319 void shrink_to_fit() {
1320 // Shrink only if slack memory is sufficiently large
1321 if (capacity() < size() * 3 / 2) {
1324 basic_fbstring(cbegin(), cend()).swap(*this);
1327 void clear() { resize(0); }
1329 bool empty() const { return size() == 0; }
1331 // C++11 21.4.5 element access:
1332 const_reference operator[](size_type pos) const {
1333 return *(begin() + pos);
1336 reference operator[](size_type pos) {
1337 return *(begin() + pos);
1340 const_reference at(size_type n) const {
1341 enforce(n <= size(), std::__throw_out_of_range, "");
1345 reference at(size_type n) {
1346 enforce(n < size(), std::__throw_out_of_range, "");
1350 // C++11 21.4.6 modifiers:
1351 basic_fbstring& operator+=(const basic_fbstring& str) {
1355 basic_fbstring& operator+=(const value_type* s) {
1359 basic_fbstring& operator+=(const value_type c) {
1364 basic_fbstring& operator+=(std::initializer_list<value_type> il) {
1369 basic_fbstring& append(const basic_fbstring& str);
1372 append(const basic_fbstring& str, const size_type pos, size_type n);
1374 basic_fbstring& append(const value_type* s, size_type n);
1376 basic_fbstring& append(const value_type* s) {
1377 return append(s, traitsLength(s));
1380 basic_fbstring& append(size_type n, value_type c);
1382 template<class InputIterator>
1383 basic_fbstring& append(InputIterator first, InputIterator last) {
1384 insert(end(), first, last);
1388 basic_fbstring& append(std::initializer_list<value_type> il) {
1389 return append(il.begin(), il.end());
1392 void push_back(const value_type c) { // primitive
1393 store_.push_back(c);
1396 basic_fbstring& assign(const basic_fbstring& str) {
1397 if (&str == this) return *this;
1398 return assign(str.data(), str.size());
1401 basic_fbstring& assign(basic_fbstring&& str) {
1402 return *this = std::move(str);
1406 assign(const basic_fbstring& str, const size_type pos, size_type n);
1408 basic_fbstring& assign(const value_type* s, const size_type n);
1410 basic_fbstring& assign(const value_type* s) {
1411 return assign(s, traitsLength(s));
1414 basic_fbstring& assign(std::initializer_list<value_type> il) {
1415 return assign(il.begin(), il.end());
1418 template <class ItOrLength, class ItOrChar>
1419 basic_fbstring& assign(ItOrLength first_or_n, ItOrChar last_or_c) {
1420 return replace(begin(), end(), first_or_n, last_or_c);
1423 basic_fbstring& insert(size_type pos1, const basic_fbstring& str) {
1424 return insert(pos1, str.data(), str.size());
1427 basic_fbstring& insert(size_type pos1, const basic_fbstring& str,
1428 size_type pos2, size_type n) {
1429 enforce(pos2 <= str.length(), std::__throw_out_of_range, "");
1430 procrustes(n, str.length() - pos2);
1431 return insert(pos1, str.data() + pos2, n);
1434 basic_fbstring& insert(size_type pos, const value_type* s, size_type n) {
1435 enforce(pos <= length(), std::__throw_out_of_range, "");
1436 insert(begin() + pos, s, s + n);
1440 basic_fbstring& insert(size_type pos, const value_type* s) {
1441 return insert(pos, s, traitsLength(s));
1444 basic_fbstring& insert(size_type pos, size_type n, value_type c) {
1445 enforce(pos <= length(), std::__throw_out_of_range, "");
1446 insert(begin() + pos, n, c);
1450 iterator insert(const_iterator p, const value_type c) {
1451 const size_type pos = p - cbegin();
1453 return begin() + pos;
1456 #ifndef _LIBSTDCXX_FBSTRING
1458 typedef std::basic_istream<value_type, traits_type> istream_type;
1459 istream_type& getlineImpl(istream_type& is, value_type delim);
1462 friend inline istream_type& getline(istream_type& is,
1463 basic_fbstring& str,
1465 return str.getlineImpl(is, delim);
1468 friend inline istream_type& getline(istream_type& is, basic_fbstring& str) {
1469 return getline(is, str, '\n');
1475 insertImplDiscr(const_iterator i, size_type n, value_type c, std::true_type);
1477 template <class InputIter>
1479 insertImplDiscr(const_iterator i, InputIter b, InputIter e, std::false_type);
1481 template <class FwdIterator>
1482 iterator insertImpl(
1486 std::forward_iterator_tag);
1488 template <class InputIterator>
1489 iterator insertImpl(
1493 std::input_iterator_tag);
1496 template <class ItOrLength, class ItOrChar>
1497 iterator insert(const_iterator p, ItOrLength first_or_n, ItOrChar last_or_c) {
1498 using Sel = std::integral_constant<
1500 std::numeric_limits<ItOrLength>::is_specialized>;
1501 return insertImplDiscr(p, first_or_n, last_or_c, Sel());
1504 iterator insert(const_iterator p, std::initializer_list<value_type> il) {
1505 return insert(p, il.begin(), il.end());
1508 basic_fbstring& erase(size_type pos = 0, size_type n = npos) {
1509 Invariant checker(*this);
1511 enforce(pos <= length(), std::__throw_out_of_range, "");
1512 procrustes(n, length() - pos);
1513 std::copy(begin() + pos + n, end(), begin() + pos);
1514 resize(length() - n);
1518 iterator erase(iterator position) {
1519 const size_type pos(position - begin());
1520 enforce(pos <= size(), std::__throw_out_of_range, "");
1522 return begin() + pos;
1525 iterator erase(iterator first, iterator last) {
1526 const size_type pos(first - begin());
1527 erase(pos, last - first);
1528 return begin() + pos;
1531 // Replaces at most n1 chars of *this, starting with pos1 with the
1533 basic_fbstring& replace(size_type pos1, size_type n1,
1534 const basic_fbstring& str) {
1535 return replace(pos1, n1, str.data(), str.size());
1538 // Replaces at most n1 chars of *this, starting with pos1,
1539 // with at most n2 chars of str starting with pos2
1540 basic_fbstring& replace(size_type pos1, size_type n1,
1541 const basic_fbstring& str,
1542 size_type pos2, size_type n2) {
1543 enforce(pos2 <= str.length(), std::__throw_out_of_range, "");
1544 return replace(pos1, n1, str.data() + pos2,
1545 std::min(n2, str.size() - pos2));
1548 // Replaces at most n1 chars of *this, starting with pos, with chars from s
1549 basic_fbstring& replace(size_type pos, size_type n1, const value_type* s) {
1550 return replace(pos, n1, s, traitsLength(s));
1553 // Replaces at most n1 chars of *this, starting with pos, with n2
1556 // consolidated with
1558 // Replaces at most n1 chars of *this, starting with pos, with at
1559 // most n2 chars of str. str must have at least n2 chars.
1560 template <class StrOrLength, class NumOrChar>
1561 basic_fbstring& replace(size_type pos, size_type n1,
1562 StrOrLength s_or_n2, NumOrChar n_or_c) {
1563 Invariant checker(*this);
1565 enforce(pos <= size(), std::__throw_out_of_range, "");
1566 procrustes(n1, length() - pos);
1567 const iterator b = begin() + pos;
1568 return replace(b, b + n1, s_or_n2, n_or_c);
1571 basic_fbstring& replace(iterator i1, iterator i2, const basic_fbstring& str) {
1572 return replace(i1, i2, str.data(), str.length());
1575 basic_fbstring& replace(iterator i1, iterator i2, const value_type* s) {
1576 return replace(i1, i2, s, traitsLength(s));
1580 basic_fbstring& replaceImplDiscr(
1583 const value_type* s,
1585 std::integral_constant<int, 2>);
1587 basic_fbstring& replaceImplDiscr(
1592 std::integral_constant<int, 1>);
1594 template <class InputIter>
1595 basic_fbstring& replaceImplDiscr(
1600 std::integral_constant<int, 0>);
1603 template <class FwdIterator>
1604 bool replaceAliased(iterator /* i1 */,
1606 FwdIterator /* s1 */,
1607 FwdIterator /* s2 */,
1612 template <class FwdIterator>
1613 bool replaceAliased(
1620 template <class FwdIterator>
1626 std::forward_iterator_tag);
1628 template <class InputIterator>
1634 std::input_iterator_tag);
1637 template <class T1, class T2>
1638 basic_fbstring& replace(iterator i1, iterator i2,
1639 T1 first_or_n_or_s, T2 last_or_c_or_n) {
1640 constexpr bool num1 = std::numeric_limits<T1>::is_specialized,
1641 num2 = std::numeric_limits<T2>::is_specialized;
1643 std::integral_constant<int, num1 ? (num2 ? 1 : -1) : (num2 ? 2 : 0)>;
1644 return replaceImplDiscr(i1, i2, first_or_n_or_s, last_or_c_or_n, Sel());
1647 size_type copy(value_type* s, size_type n, size_type pos = 0) const {
1648 enforce(pos <= size(), std::__throw_out_of_range, "");
1649 procrustes(n, size() - pos);
1652 fbstring_detail::podCopy(data() + pos, data() + pos + n, s);
1657 void swap(basic_fbstring& rhs) {
1658 store_.swap(rhs.store_);
1661 const value_type* c_str() const {
1662 return store_.c_str();
1665 const value_type* data() const { return c_str(); }
1667 allocator_type get_allocator() const {
1668 return allocator_type();
1671 size_type find(const basic_fbstring& str, size_type pos = 0) const {
1672 return find(str.data(), pos, str.length());
1675 size_type find(const value_type* needle, size_type pos, size_type nsize)
1678 size_type find(const value_type* s, size_type pos = 0) const {
1679 return find(s, pos, traitsLength(s));
1682 size_type find (value_type c, size_type pos = 0) const {
1683 return find(&c, pos, 1);
1686 size_type rfind(const basic_fbstring& str, size_type pos = npos) const {
1687 return rfind(str.data(), pos, str.length());
1690 size_type rfind(const value_type* s, size_type pos, size_type n) const;
1692 size_type rfind(const value_type* s, size_type pos = npos) const {
1693 return rfind(s, pos, traitsLength(s));
1696 size_type rfind(value_type c, size_type pos = npos) const {
1697 return rfind(&c, pos, 1);
1700 size_type find_first_of(const basic_fbstring& str, size_type pos = 0) const {
1701 return find_first_of(str.data(), pos, str.length());
1704 size_type find_first_of(const value_type* s, size_type pos, size_type n)
1707 size_type find_first_of(const value_type* s, size_type pos = 0) const {
1708 return find_first_of(s, pos, traitsLength(s));
1711 size_type find_first_of(value_type c, size_type pos = 0) const {
1712 return find_first_of(&c, pos, 1);
1715 size_type find_last_of(const basic_fbstring& str, size_type pos = npos)
1717 return find_last_of(str.data(), pos, str.length());
1720 size_type find_last_of(const value_type* s, size_type pos, size_type n) const;
1722 size_type find_last_of (const value_type* s,
1723 size_type pos = npos) const {
1724 return find_last_of(s, pos, traitsLength(s));
1727 size_type find_last_of (value_type c, size_type pos = npos) const {
1728 return find_last_of(&c, pos, 1);
1731 size_type find_first_not_of(const basic_fbstring& str,
1732 size_type pos = 0) const {
1733 return find_first_not_of(str.data(), pos, str.size());
1736 size_type find_first_not_of(const value_type* s, size_type pos, size_type n)
1739 size_type find_first_not_of(const value_type* s,
1740 size_type pos = 0) const {
1741 return find_first_not_of(s, pos, traitsLength(s));
1744 size_type find_first_not_of(value_type c, size_type pos = 0) const {
1745 return find_first_not_of(&c, pos, 1);
1748 size_type find_last_not_of(const basic_fbstring& str,
1749 size_type pos = npos) const {
1750 return find_last_not_of(str.data(), pos, str.length());
1753 size_type find_last_not_of(const value_type* s, size_type pos, size_type n)
1756 size_type find_last_not_of(const value_type* s,
1757 size_type pos = npos) const {
1758 return find_last_not_of(s, pos, traitsLength(s));
1761 size_type find_last_not_of (value_type c, size_type pos = npos) const {
1762 return find_last_not_of(&c, pos, 1);
1765 basic_fbstring substr(size_type pos = 0, size_type n = npos) const& {
1766 enforce(pos <= size(), std::__throw_out_of_range, "");
1767 return basic_fbstring(data() + pos, std::min(n, size() - pos));
1770 basic_fbstring substr(size_type pos = 0, size_type n = npos) && {
1771 enforce(pos <= size(), std::__throw_out_of_range, "");
1776 return std::move(*this);
1779 int compare(const basic_fbstring& str) const {
1780 // FIX due to Goncalo N M de Carvalho July 18, 2005
1781 return compare(0, size(), str);
1784 int compare(size_type pos1, size_type n1,
1785 const basic_fbstring& str) const {
1786 return compare(pos1, n1, str.data(), str.size());
1789 int compare(size_type pos1, size_type n1,
1790 const value_type* s) const {
1791 return compare(pos1, n1, s, traitsLength(s));
1794 int compare(size_type pos1, size_type n1,
1795 const value_type* s, size_type n2) const {
1796 enforce(pos1 <= size(), std::__throw_out_of_range, "");
1797 procrustes(n1, size() - pos1);
1798 // The line below fixed by Jean-Francois Bastien, 04-23-2007. Thanks!
1799 const int r = traits_type::compare(pos1 + data(), s, std::min(n1, n2));
1800 return r != 0 ? r : n1 > n2 ? 1 : n1 < n2 ? -1 : 0;
1803 int compare(size_type pos1, size_type n1,
1804 const basic_fbstring& str,
1805 size_type pos2, size_type n2) const {
1806 enforce(pos2 <= str.size(), std::__throw_out_of_range, "");
1807 return compare(pos1, n1, str.data() + pos2,
1808 std::min(n2, str.size() - pos2));
1811 // Code from Jean-Francois Bastien (03/26/2007)
1812 int compare(const value_type* s) const {
1813 // Could forward to compare(0, size(), s, traitsLength(s))
1814 // but that does two extra checks
1815 const size_type n1(size()), n2(traitsLength(s));
1816 const int r = traits_type::compare(data(), s, std::min(n1, n2));
1817 return r != 0 ? r : n1 > n2 ? 1 : n1 < n2 ? -1 : 0;
1825 template <typename E, class T, class A, class S>
1826 FOLLY_MALLOC_NOINLINE inline typename basic_fbstring<E, T, A, S>::size_type
1827 basic_fbstring<E, T, A, S>::traitsLength(const value_type* s) {
1828 return s ? traits_type::length(s)
1829 : (std::__throw_logic_error(
1830 "basic_fbstring: null pointer initializer not valid"),
1834 template <typename E, class T, class A, class S>
1835 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::operator=(
1836 const basic_fbstring& lhs) {
1837 Invariant checker(*this);
1839 if (FBSTRING_UNLIKELY(&lhs == this)) {
1843 return assign(lhs.data(), lhs.size());
1847 template <typename E, class T, class A, class S>
1848 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::operator=(
1849 basic_fbstring&& goner) noexcept {
1850 if (FBSTRING_UNLIKELY(&goner == this)) {
1851 // Compatibility with std::basic_string<>,
1852 // C++11 21.4.2 [string.cons] / 23 requires self-move-assignment support.
1855 // No need of this anymore
1856 this->~basic_fbstring();
1857 // Move the goner into this
1858 new (&store_) S(std::move(goner.store_));
1862 template <typename E, class T, class A, class S>
1863 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::operator=(
1864 const value_type c) {
1865 Invariant checker(*this);
1868 store_.expandNoinit(1);
1869 } else if (store_.isShared()) {
1870 basic_fbstring(1, c).swap(*this);
1873 store_.shrink(size() - 1);
1879 template <typename E, class T, class A, class S>
1880 inline void basic_fbstring<E, T, A, S>::resize(
1881 const size_type n, const value_type c /*= value_type()*/) {
1882 Invariant checker(*this);
1884 auto size = this->size();
1886 store_.shrink(size - n);
1888 auto const delta = n - size;
1889 auto pData = store_.expandNoinit(delta);
1890 fbstring_detail::podFill(pData, pData + delta, c);
1892 FBSTRING_ASSERT(this->size() == n);
1895 template <typename E, class T, class A, class S>
1896 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::append(
1897 const basic_fbstring& str) {
1899 auto desiredSize = size() + str.size();
1901 append(str.data(), str.size());
1902 FBSTRING_ASSERT(size() == desiredSize);
1906 template <typename E, class T, class A, class S>
1907 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::append(
1908 const basic_fbstring& str, const size_type pos, size_type n) {
1909 const size_type sz = str.size();
1910 enforce(pos <= sz, std::__throw_out_of_range, "");
1911 procrustes(n, sz - pos);
1912 return append(str.data() + pos, n);
1915 template <typename E, class T, class A, class S>
1916 FOLLY_MALLOC_NOINLINE inline basic_fbstring<E, T, A, S>&
1917 basic_fbstring<E, T, A, S>::append(const value_type* s, size_type n) {
1918 Invariant checker(*this);
1920 if (FBSTRING_UNLIKELY(!n)) {
1921 // Unlikely but must be done
1924 auto const oldSize = size();
1925 auto const oldData = data();
1926 auto pData = store_.expandNoinit(n, /* expGrowth = */ true);
1928 // Check for aliasing (rare). We could use "<=" here but in theory
1929 // those do not work for pointers unless the pointers point to
1930 // elements in the same array. For that reason we use
1931 // std::less_equal, which is guaranteed to offer a total order
1932 // over pointers. See discussion at http://goo.gl/Cy2ya for more
1934 std::less_equal<const value_type*> le;
1935 if (FBSTRING_UNLIKELY(le(oldData, s) && !le(oldData + oldSize, s))) {
1936 FBSTRING_ASSERT(le(s + n, oldData + oldSize));
1937 // expandNoinit() could have moved the storage, restore the source.
1938 s = data() + (s - oldData);
1939 fbstring_detail::podMove(s, s + n, pData);
1941 fbstring_detail::podCopy(s, s + n, pData);
1944 FBSTRING_ASSERT(size() == oldSize + n);
1948 template <typename E, class T, class A, class S>
1949 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::append(
1950 size_type n, value_type c) {
1951 Invariant checker(*this);
1952 auto pData = store_.expandNoinit(n, /* expGrowth = */ true);
1953 fbstring_detail::podFill(pData, pData + n, c);
1957 template <typename E, class T, class A, class S>
1958 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::assign(
1959 const basic_fbstring& str, const size_type pos, size_type n) {
1960 const size_type sz = str.size();
1961 enforce(pos <= sz, std::__throw_out_of_range, "");
1962 procrustes(n, sz - pos);
1963 return assign(str.data() + pos, n);
1966 template <typename E, class T, class A, class S>
1967 FOLLY_MALLOC_NOINLINE inline basic_fbstring<E, T, A, S>&
1968 basic_fbstring<E, T, A, S>::assign(const value_type* s, const size_type n) {
1969 Invariant checker(*this);
1973 } else if (size() >= n) {
1974 // s can alias this, we need to use podMove.
1975 fbstring_detail::podMove(s, s + n, store_.mutableData());
1976 store_.shrink(size() - n);
1977 FBSTRING_ASSERT(size() == n);
1979 // If n is larger than size(), s cannot alias this string's
1982 // Do not use exponential growth here: assign() should be tight,
1983 // to mirror the behavior of the equivalent constructor.
1984 fbstring_detail::podCopy(s, s + n, store_.expandNoinit(n));
1987 FBSTRING_ASSERT(size() == n);
1991 #ifndef _LIBSTDCXX_FBSTRING
1992 template <typename E, class T, class A, class S>
1993 inline typename basic_fbstring<E, T, A, S>::istream_type&
1994 basic_fbstring<E, T, A, S>::getlineImpl(istream_type & is, value_type delim) {
1995 Invariant checker(*this);
2000 size_t avail = capacity() - size;
2001 // fbstring has 1 byte extra capacity for the null terminator,
2002 // and getline null-terminates the read string.
2003 is.getline(store_.expandNoinit(avail), avail + 1, delim);
2004 size += is.gcount();
2006 if (is.bad() || is.eof() || !is.fail()) {
2007 // Done by either failure, end of file, or normal read.
2008 if (!is.bad() && !is.eof()) {
2009 --size; // gcount() also accounts for the delimiter.
2015 FBSTRING_ASSERT(size == this->size());
2016 FBSTRING_ASSERT(size == capacity());
2017 // Start at minimum allocation 63 + terminator = 64.
2018 reserve(std::max<size_t>(63, 3 * size / 2));
2019 // Clear the error so we can continue reading.
2026 template <typename E, class T, class A, class S>
2027 inline typename basic_fbstring<E, T, A, S>::size_type
2028 basic_fbstring<E, T, A, S>::find(
2029 const value_type* needle, const size_type pos, const size_type nsize)
2031 auto const size = this->size();
2032 // nsize + pos can overflow (eg pos == npos), guard against that by checking
2033 // that nsize + pos does not wrap around.
2034 if (nsize + pos > size || nsize + pos < pos) {
2041 // Don't use std::search, use a Boyer-Moore-like trick by comparing
2042 // the last characters first
2043 auto const haystack = data();
2044 auto const nsize_1 = nsize - 1;
2045 auto const lastNeedle = needle[nsize_1];
2047 // Boyer-Moore skip value for the last char in the needle. Zero is
2048 // not a valid value; skip will be computed the first time it's
2052 const E* i = haystack + pos;
2053 auto iEnd = haystack + size - nsize_1;
2056 // Boyer-Moore: match the last element in the needle
2057 while (i[nsize_1] != lastNeedle) {
2063 // Here we know that the last char matches
2064 // Continue in pedestrian mode
2065 for (size_t j = 0;;) {
2066 FBSTRING_ASSERT(j < nsize);
2067 if (i[j] != needle[j]) {
2068 // Not found, we can skip
2069 // Compute the skip value lazily
2072 while (skip <= nsize_1 && needle[nsize_1 - skip] != lastNeedle) {
2079 // Check if done searching
2082 return i - haystack;
2089 template <typename E, class T, class A, class S>
2090 inline typename basic_fbstring<E, T, A, S>::iterator
2091 basic_fbstring<E, T, A, S>::insertImplDiscr(
2092 const_iterator i, size_type n, value_type c, std::true_type) {
2093 Invariant checker(*this);
2095 FBSTRING_ASSERT(i >= cbegin() && i <= cend());
2096 const size_type pos = i - cbegin();
2098 auto oldSize = size();
2099 store_.expandNoinit(n, /* expGrowth = */ true);
2101 fbstring_detail::podMove(b + pos, b + oldSize, b + pos + n);
2102 fbstring_detail::podFill(b + pos, b + pos + n, c);
2107 template <typename E, class T, class A, class S>
2108 template <class InputIter>
2109 inline typename basic_fbstring<E, T, A, S>::iterator
2110 basic_fbstring<E, T, A, S>::insertImplDiscr(
2111 const_iterator i, InputIter b, InputIter e, std::false_type) {
2113 i, b, e, typename std::iterator_traits<InputIter>::iterator_category());
2116 template <typename E, class T, class A, class S>
2117 template <class FwdIterator>
2118 inline typename basic_fbstring<E, T, A, S>::iterator
2119 basic_fbstring<E, T, A, S>::insertImpl(
2123 std::forward_iterator_tag) {
2124 Invariant checker(*this);
2126 FBSTRING_ASSERT(i >= cbegin() && i <= cend());
2127 const size_type pos = i - cbegin();
2128 auto n = std::distance(s1, s2);
2129 FBSTRING_ASSERT(n >= 0);
2131 auto oldSize = size();
2132 store_.expandNoinit(n, /* expGrowth = */ true);
2134 fbstring_detail::podMove(b + pos, b + oldSize, b + pos + n);
2135 std::copy(s1, s2, b + pos);
2140 template <typename E, class T, class A, class S>
2141 template <class InputIterator>
2142 inline typename basic_fbstring<E, T, A, S>::iterator
2143 basic_fbstring<E, T, A, S>::insertImpl(
2147 std::input_iterator_tag) {
2148 const auto pos = i - cbegin();
2149 basic_fbstring temp(cbegin(), i);
2150 for (; b != e; ++b) {
2153 temp.append(i, cend());
2155 return begin() + pos;
2158 template <typename E, class T, class A, class S>
2159 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::replaceImplDiscr(
2162 const value_type* s,
2164 std::integral_constant<int, 2>) {
2165 FBSTRING_ASSERT(i1 <= i2);
2166 FBSTRING_ASSERT(begin() <= i1 && i1 <= end());
2167 FBSTRING_ASSERT(begin() <= i2 && i2 <= end());
2168 return replace(i1, i2, s, s + n);
2171 template <typename E, class T, class A, class S>
2172 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::replaceImplDiscr(
2177 std::integral_constant<int, 1>) {
2178 const size_type n1 = i2 - i1;
2180 std::fill(i1, i1 + n2, c);
2183 std::fill(i1, i2, c);
2184 insert(i2, n2 - n1, c);
2186 FBSTRING_ASSERT(isSane());
2190 template <typename E, class T, class A, class S>
2191 template <class InputIter>
2192 inline basic_fbstring<E, T, A, S>& basic_fbstring<E, T, A, S>::replaceImplDiscr(
2197 std::integral_constant<int, 0>) {
2198 using Cat = typename std::iterator_traits<InputIter>::iterator_category;
2199 replaceImpl(i1, i2, b, e, Cat());
2203 template <typename E, class T, class A, class S>
2204 template <class FwdIterator>
2205 inline bool basic_fbstring<E, T, A, S>::replaceAliased(
2206 iterator i1, iterator i2, FwdIterator s1, FwdIterator s2, std::true_type) {
2207 std::less_equal<const value_type*> le{};
2208 const bool aliased = le(&*begin(), &*s1) && le(&*s1, &*end());
2212 // Aliased replace, copy to new string
2213 basic_fbstring temp;
2214 temp.reserve(size() - (i2 - i1) + std::distance(s1, s2));
2215 temp.append(begin(), i1).append(s1, s2).append(i2, end());
2220 template <typename E, class T, class A, class S>
2221 template <class FwdIterator>
2222 inline void basic_fbstring<E, T, A, S>::replaceImpl(
2227 std::forward_iterator_tag) {
2228 Invariant checker(*this);
2230 // Handle aliased replace
2231 using Sel = std::integral_constant<
2233 std::is_same<FwdIterator, iterator>::value ||
2234 std::is_same<FwdIterator, const_iterator>::value>;
2235 if (replaceAliased(i1, i2, s1, s2, Sel())) {
2239 auto const n1 = i2 - i1;
2240 FBSTRING_ASSERT(n1 >= 0);
2241 auto const n2 = std::distance(s1, s2);
2242 FBSTRING_ASSERT(n2 >= 0);
2246 std::copy(s1, s2, i1);
2250 s1 = fbstring_detail::copy_n(s1, n1, i1).first;
2253 FBSTRING_ASSERT(isSane());
2256 template <typename E, class T, class A, class S>
2257 template <class InputIterator>
2258 inline void basic_fbstring<E, T, A, S>::replaceImpl(
2263 std::input_iterator_tag) {
2264 basic_fbstring temp(begin(), i1);
2265 temp.append(b, e).append(i2, end());
2269 template <typename E, class T, class A, class S>
2270 inline typename basic_fbstring<E, T, A, S>::size_type
2271 basic_fbstring<E, T, A, S>::rfind(
2272 const value_type* s, size_type pos, size_type n) const {
2276 pos = std::min(pos, length() - n);
2281 const_iterator i(begin() + pos);
2283 if (traits_type::eq(*i, *s) && traits_type::compare(&*i, s, n) == 0) {
2293 template <typename E, class T, class A, class S>
2294 inline typename basic_fbstring<E, T, A, S>::size_type
2295 basic_fbstring<E, T, A, S>::find_first_of(
2296 const value_type* s, size_type pos, size_type n) const {
2297 if (pos > length() || n == 0) {
2300 const_iterator i(begin() + pos), finish(end());
2301 for (; i != finish; ++i) {
2302 if (traits_type::find(s, n, *i) != 0) {
2309 template <typename E, class T, class A, class S>
2310 inline typename basic_fbstring<E, T, A, S>::size_type
2311 basic_fbstring<E, T, A, S>::find_last_of(
2312 const value_type* s, size_type pos, size_type n) const {
2313 if (!empty() && n > 0) {
2314 pos = std::min(pos, length() - 1);
2315 const_iterator i(begin() + pos);
2317 if (traits_type::find(s, n, *i) != 0) {
2328 template <typename E, class T, class A, class S>
2329 inline typename basic_fbstring<E, T, A, S>::size_type
2330 basic_fbstring<E, T, A, S>::find_first_not_of(
2331 const value_type* s, size_type pos, size_type n) const {
2332 if (pos < length()) {
2333 const_iterator i(begin() + pos), finish(end());
2334 for (; i != finish; ++i) {
2335 if (traits_type::find(s, n, *i) == 0) {
2343 template <typename E, class T, class A, class S>
2344 inline typename basic_fbstring<E, T, A, S>::size_type
2345 basic_fbstring<E, T, A, S>::find_last_not_of(
2346 const value_type* s, size_type pos, size_type n) const {
2347 if (!this->empty()) {
2348 pos = std::min(pos, size() - 1);
2349 const_iterator i(begin() + pos);
2351 if (traits_type::find(s, n, *i) == 0) {
2362 // non-member functions
2364 template <typename E, class T, class A, class S>
2366 basic_fbstring<E, T, A, S> operator+(const basic_fbstring<E, T, A, S>& lhs,
2367 const basic_fbstring<E, T, A, S>& rhs) {
2369 basic_fbstring<E, T, A, S> result;
2370 result.reserve(lhs.size() + rhs.size());
2371 result.append(lhs).append(rhs);
2372 return std::move(result);
2376 template <typename E, class T, class A, class S>
2378 basic_fbstring<E, T, A, S> operator+(basic_fbstring<E, T, A, S>&& lhs,
2379 const basic_fbstring<E, T, A, S>& rhs) {
2380 return std::move(lhs.append(rhs));
2384 template <typename E, class T, class A, class S>
2386 basic_fbstring<E, T, A, S> operator+(const basic_fbstring<E, T, A, S>& lhs,
2387 basic_fbstring<E, T, A, S>&& rhs) {
2388 if (rhs.capacity() >= lhs.size() + rhs.size()) {
2389 // Good, at least we don't need to reallocate
2390 return std::move(rhs.insert(0, lhs));
2392 // Meh, no go. Forward to operator+(const&, const&).
2393 auto const& rhsC = rhs;
2398 template <typename E, class T, class A, class S>
2400 basic_fbstring<E, T, A, S> operator+(basic_fbstring<E, T, A, S>&& lhs,
2401 basic_fbstring<E, T, A, S>&& rhs) {
2402 return std::move(lhs.append(rhs));
2406 template <typename E, class T, class A, class S>
2408 basic_fbstring<E, T, A, S> operator+(
2410 const basic_fbstring<E, T, A, S>& rhs) {
2412 basic_fbstring<E, T, A, S> result;
2413 const auto len = basic_fbstring<E, T, A, S>::traits_type::length(lhs);
2414 result.reserve(len + rhs.size());
2415 result.append(lhs, len).append(rhs);
2420 template <typename E, class T, class A, class S>
2422 basic_fbstring<E, T, A, S> operator+(
2424 basic_fbstring<E, T, A, S>&& rhs) {
2426 const auto len = basic_fbstring<E, T, A, S>::traits_type::length(lhs);
2427 if (rhs.capacity() >= len + rhs.size()) {
2428 // Good, at least we don't need to reallocate
2429 rhs.insert(rhs.begin(), lhs, lhs + len);
2432 // Meh, no go. Do it by hand since we have len already.
2433 basic_fbstring<E, T, A, S> result;
2434 result.reserve(len + rhs.size());
2435 result.append(lhs, len).append(rhs);
2440 template <typename E, class T, class A, class S>
2442 basic_fbstring<E, T, A, S> operator+(
2444 const basic_fbstring<E, T, A, S>& rhs) {
2446 basic_fbstring<E, T, A, S> result;
2447 result.reserve(1 + rhs.size());
2448 result.push_back(lhs);
2454 template <typename E, class T, class A, class S>
2456 basic_fbstring<E, T, A, S> operator+(
2458 basic_fbstring<E, T, A, S>&& rhs) {
2460 if (rhs.capacity() > rhs.size()) {
2461 // Good, at least we don't need to reallocate
2462 rhs.insert(rhs.begin(), lhs);
2465 // Meh, no go. Forward to operator+(E, const&).
2466 auto const& rhsC = rhs;
2471 template <typename E, class T, class A, class S>
2473 basic_fbstring<E, T, A, S> operator+(
2474 const basic_fbstring<E, T, A, S>& lhs,
2477 typedef typename basic_fbstring<E, T, A, S>::size_type size_type;
2478 typedef typename basic_fbstring<E, T, A, S>::traits_type traits_type;
2480 basic_fbstring<E, T, A, S> result;
2481 const size_type len = traits_type::length(rhs);
2482 result.reserve(lhs.size() + len);
2483 result.append(lhs).append(rhs, len);
2487 // C++11 21.4.8.1/10
2488 template <typename E, class T, class A, class S>
2490 basic_fbstring<E, T, A, S> operator+(
2491 basic_fbstring<E, T, A, S>&& lhs,
2494 return std::move(lhs += rhs);
2497 // C++11 21.4.8.1/11
2498 template <typename E, class T, class A, class S>
2500 basic_fbstring<E, T, A, S> operator+(
2501 const basic_fbstring<E, T, A, S>& lhs,
2504 basic_fbstring<E, T, A, S> result;
2505 result.reserve(lhs.size() + 1);
2507 result.push_back(rhs);
2511 // C++11 21.4.8.1/12
2512 template <typename E, class T, class A, class S>
2514 basic_fbstring<E, T, A, S> operator+(
2515 basic_fbstring<E, T, A, S>&& lhs,
2518 return std::move(lhs += rhs);
2521 template <typename E, class T, class A, class S>
2523 bool operator==(const basic_fbstring<E, T, A, S>& lhs,
2524 const basic_fbstring<E, T, A, S>& rhs) {
2525 return lhs.size() == rhs.size() && lhs.compare(rhs) == 0; }
2527 template <typename E, class T, class A, class S>
2529 bool operator==(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2530 const basic_fbstring<E, T, A, S>& rhs) {
2531 return rhs == lhs; }
2533 template <typename E, class T, class A, class S>
2535 bool operator==(const basic_fbstring<E, T, A, S>& lhs,
2536 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2537 return lhs.compare(rhs) == 0; }
2539 template <typename E, class T, class A, class S>
2541 bool operator!=(const basic_fbstring<E, T, A, S>& lhs,
2542 const basic_fbstring<E, T, A, S>& rhs) {
2543 return !(lhs == rhs); }
2545 template <typename E, class T, class A, class S>
2547 bool operator!=(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2548 const basic_fbstring<E, T, A, S>& rhs) {
2549 return !(lhs == rhs); }
2551 template <typename E, class T, class A, class S>
2553 bool operator!=(const basic_fbstring<E, T, A, S>& lhs,
2554 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2555 return !(lhs == rhs); }
2557 template <typename E, class T, class A, class S>
2559 bool operator<(const basic_fbstring<E, T, A, S>& lhs,
2560 const basic_fbstring<E, T, A, S>& rhs) {
2561 return lhs.compare(rhs) < 0; }
2563 template <typename E, class T, class A, class S>
2565 bool operator<(const basic_fbstring<E, T, A, S>& lhs,
2566 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2567 return lhs.compare(rhs) < 0; }
2569 template <typename E, class T, class A, class S>
2571 bool operator<(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2572 const basic_fbstring<E, T, A, S>& rhs) {
2573 return rhs.compare(lhs) > 0; }
2575 template <typename E, class T, class A, class S>
2577 bool operator>(const basic_fbstring<E, T, A, S>& lhs,
2578 const basic_fbstring<E, T, A, S>& rhs) {
2581 template <typename E, class T, class A, class S>
2583 bool operator>(const basic_fbstring<E, T, A, S>& lhs,
2584 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2587 template <typename E, class T, class A, class S>
2589 bool operator>(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2590 const basic_fbstring<E, T, A, S>& rhs) {
2593 template <typename E, class T, class A, class S>
2595 bool operator<=(const basic_fbstring<E, T, A, S>& lhs,
2596 const basic_fbstring<E, T, A, S>& rhs) {
2597 return !(rhs < lhs); }
2599 template <typename E, class T, class A, class S>
2601 bool operator<=(const basic_fbstring<E, T, A, S>& lhs,
2602 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2603 return !(rhs < lhs); }
2605 template <typename E, class T, class A, class S>
2607 bool operator<=(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2608 const basic_fbstring<E, T, A, S>& rhs) {
2609 return !(rhs < lhs); }
2611 template <typename E, class T, class A, class S>
2613 bool operator>=(const basic_fbstring<E, T, A, S>& lhs,
2614 const basic_fbstring<E, T, A, S>& rhs) {
2615 return !(lhs < rhs); }
2617 template <typename E, class T, class A, class S>
2619 bool operator>=(const basic_fbstring<E, T, A, S>& lhs,
2620 const typename basic_fbstring<E, T, A, S>::value_type* rhs) {
2621 return !(lhs < rhs); }
2623 template <typename E, class T, class A, class S>
2625 bool operator>=(const typename basic_fbstring<E, T, A, S>::value_type* lhs,
2626 const basic_fbstring<E, T, A, S>& rhs) {
2627 return !(lhs < rhs);
2631 template <typename E, class T, class A, class S>
2632 void swap(basic_fbstring<E, T, A, S>& lhs, basic_fbstring<E, T, A, S>& rhs) {
2636 // TODO: make this faster.
2637 template <typename E, class T, class A, class S>
2640 typename basic_fbstring<E, T, A, S>::value_type,
2641 typename basic_fbstring<E, T, A, S>::traits_type>&
2643 std::basic_istream<typename basic_fbstring<E, T, A, S>::value_type,
2644 typename basic_fbstring<E, T, A, S>::traits_type>& is,
2645 basic_fbstring<E, T, A, S>& str) {
2646 typedef std::basic_istream<
2647 typename basic_fbstring<E, T, A, S>::value_type,
2648 typename basic_fbstring<E, T, A, S>::traits_type>
2650 typename _istream_type::sentry sentry(is);
2651 size_t extracted = 0;
2652 auto err = _istream_type::goodbit;
2654 auto n = is.width();
2659 for (auto got = is.rdbuf()->sgetc(); extracted != size_t(n); ++extracted) {
2660 if (got == T::eof()) {
2661 err |= _istream_type::eofbit;
2669 got = is.rdbuf()->snextc();
2673 err |= _istream_type::failbit;
2681 template <typename E, class T, class A, class S>
2683 std::basic_ostream<typename basic_fbstring<E, T, A, S>::value_type,
2684 typename basic_fbstring<E, T, A, S>::traits_type>&
2686 std::basic_ostream<typename basic_fbstring<E, T, A, S>::value_type,
2687 typename basic_fbstring<E, T, A, S>::traits_type>& os,
2688 const basic_fbstring<E, T, A, S>& str) {
2690 typedef std::basic_ostream<
2691 typename basic_fbstring<E, T, A, S>::value_type,
2692 typename basic_fbstring<E, T, A, S>::traits_type>
2694 typename _ostream_type::sentry _s(os);
2696 typedef std::ostreambuf_iterator<
2697 typename basic_fbstring<E, T, A, S>::value_type,
2698 typename basic_fbstring<E, T, A, S>::traits_type> _Ip;
2699 size_t __len = str.size();
2701 (os.flags() & _ostream_type::adjustfield) == _ostream_type::left;
2702 if (__pad_and_output(_Ip(os),
2704 __left ? str.data() + __len : str.data(),
2707 os.fill()).failed()) {
2708 os.setstate(_ostream_type::badbit | _ostream_type::failbit);
2711 #elif defined(_MSC_VER)
2712 typedef decltype(os.precision()) streamsize;
2713 // MSVC doesn't define __ostream_insert
2714 os.write(str.data(), static_cast<streamsize>(str.size()));
2716 std::__ostream_insert(os, str.data(), str.size());
2721 template <typename E1, class T, class A, class S>
2722 constexpr typename basic_fbstring<E1, T, A, S>::size_type
2723 basic_fbstring<E1, T, A, S>::npos;
2725 #ifndef _LIBSTDCXX_FBSTRING
2726 // basic_string compatibility routines
2728 template <typename E, class T, class A, class S>
2730 bool operator==(const basic_fbstring<E, T, A, S>& lhs,
2731 const std::string& rhs) {
2732 return lhs.compare(0, lhs.size(), rhs.data(), rhs.size()) == 0;
2735 template <typename E, class T, class A, class S>
2737 bool operator==(const std::string& lhs,
2738 const basic_fbstring<E, T, A, S>& rhs) {
2742 template <typename E, class T, class A, class S>
2744 bool operator!=(const basic_fbstring<E, T, A, S>& lhs,
2745 const std::string& rhs) {
2746 return !(lhs == rhs);
2749 template <typename E, class T, class A, class S>
2751 bool operator!=(const std::string& lhs,
2752 const basic_fbstring<E, T, A, S>& rhs) {
2753 return !(lhs == rhs);
2756 #if !defined(_LIBSTDCXX_FBSTRING)
2757 typedef basic_fbstring<char> fbstring;
2760 // fbstring is relocatable
2761 template <class T, class R, class A, class S>
2762 FOLLY_ASSUME_RELOCATABLE(basic_fbstring<T, R, A, S>);
2765 _GLIBCXX_END_NAMESPACE_VERSION
2768 } // namespace folly
2770 #ifndef _LIBSTDCXX_FBSTRING
2772 // Hash functions to make fbstring usable with e.g. hash_map
2774 // Handle interaction with different C++ standard libraries, which
2775 // expect these types to be in different namespaces.
2777 #define FOLLY_FBSTRING_HASH1(T) \
2779 struct hash< ::folly::basic_fbstring<T>> { \
2780 size_t operator()(const ::folly::basic_fbstring<T>& s) const { \
2781 return ::folly::hash::fnv32_buf(s.data(), s.size() * sizeof(T)); \
2785 // The C++11 standard says that these four are defined
2786 #define FOLLY_FBSTRING_HASH \
2787 FOLLY_FBSTRING_HASH1(char) \
2788 FOLLY_FBSTRING_HASH1(char16_t) \
2789 FOLLY_FBSTRING_HASH1(char32_t) \
2790 FOLLY_FBSTRING_HASH1(wchar_t)
2798 #if FOLLY_HAVE_DEPRECATED_ASSOC
2799 #if defined(_GLIBCXX_SYMVER) && !defined(__BIONIC__)
2800 namespace __gnu_cxx {
2804 } // namespace __gnu_cxx
2805 #endif // _GLIBCXX_SYMVER && !__BIONIC__
2806 #endif // FOLLY_HAVE_DEPRECATED_ASSOC
2808 #undef FOLLY_FBSTRING_HASH
2809 #undef FOLLY_FBSTRING_HASH1
2811 #endif // _LIBSTDCXX_FBSTRING
2813 #pragma GCC diagnostic pop
2815 #undef FBSTRING_DISABLE_SSO
2816 #undef FBSTRING_SANITIZE_ADDRESS
2818 #undef FBSTRING_LIKELY
2819 #undef FBSTRING_UNLIKELY
2820 #undef FBSTRING_ASSERT