1 //===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the SmallVector class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_SMALLVECTOR_H
15 #define LLVM_ADT_SMALLVECTOR_H
17 #include "llvm/ADT/iterator_range.h"
18 #include "llvm/Support/AlignOf.h"
19 #include "llvm/Support/Compiler.h"
20 #include "llvm/Support/MathExtras.h"
21 #include "llvm/Support/type_traits.h"
27 #include <initializer_list>
31 #include <type_traits>
36 /// This is all the non-templated stuff common to all SmallVectors.
37 class SmallVectorBase {
39 void *BeginX, *EndX, *CapacityX;
42 SmallVectorBase(void *FirstEl, size_t Size)
43 : BeginX(FirstEl), EndX(FirstEl), CapacityX((char*)FirstEl+Size) {}
45 /// This is an implementation of the grow() method which only works
46 /// on POD-like data types and is out of line to reduce code duplication.
47 void grow_pod(void *FirstEl, size_t MinSizeInBytes, size_t TSize);
50 /// This returns size()*sizeof(T).
51 size_t size_in_bytes() const {
52 return size_t((char*)EndX - (char*)BeginX);
55 /// capacity_in_bytes - This returns capacity()*sizeof(T).
56 size_t capacity_in_bytes() const {
57 return size_t((char*)CapacityX - (char*)BeginX);
60 LLVM_NODISCARD bool empty() const { return BeginX == EndX; }
63 /// This is the part of SmallVectorTemplateBase which does not depend on whether
64 /// the type T is a POD. The extra dummy template argument is used by ArrayRef
65 /// to avoid unnecessarily requiring T to be complete.
66 template <typename T, typename = void>
67 class SmallVectorTemplateCommon : public SmallVectorBase {
69 template <typename, unsigned> friend struct SmallVectorStorage;
71 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
72 // don't want it to be automatically run, so we need to represent the space as
73 // something else. Use an array of char of sufficient alignment.
74 typedef AlignedCharArrayUnion<T> U;
76 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
79 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(&FirstEl, Size) {}
81 void grow_pod(size_t MinSizeInBytes, size_t TSize) {
82 SmallVectorBase::grow_pod(&FirstEl, MinSizeInBytes, TSize);
85 /// Return true if this is a smallvector which has not had dynamic
86 /// memory allocated for it.
87 bool isSmall() const {
88 return BeginX == static_cast<const void*>(&FirstEl);
91 /// Put this vector in a state of being small.
93 BeginX = EndX = CapacityX = &FirstEl;
96 void setEnd(T *P) { this->EndX = P; }
99 typedef size_t size_type;
100 typedef ptrdiff_t difference_type;
101 typedef T value_type;
103 typedef const T *const_iterator;
105 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
106 typedef std::reverse_iterator<iterator> reverse_iterator;
108 typedef T &reference;
109 typedef const T &const_reference;
111 typedef const T *const_pointer;
113 // forward iterator creation methods.
114 LLVM_ATTRIBUTE_ALWAYS_INLINE
115 iterator begin() { return (iterator)this->BeginX; }
116 LLVM_ATTRIBUTE_ALWAYS_INLINE
117 const_iterator begin() const { return (const_iterator)this->BeginX; }
118 LLVM_ATTRIBUTE_ALWAYS_INLINE
119 iterator end() { return (iterator)this->EndX; }
120 LLVM_ATTRIBUTE_ALWAYS_INLINE
121 const_iterator end() const { return (const_iterator)this->EndX; }
124 iterator capacity_ptr() { return (iterator)this->CapacityX; }
125 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
128 // reverse iterator creation methods.
129 reverse_iterator rbegin() { return reverse_iterator(end()); }
130 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
131 reverse_iterator rend() { return reverse_iterator(begin()); }
132 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
134 LLVM_ATTRIBUTE_ALWAYS_INLINE
135 size_type size() const { return end()-begin(); }
136 size_type max_size() const { return size_type(-1) / sizeof(T); }
138 /// Return the total number of elements in the currently allocated buffer.
139 size_t capacity() const { return capacity_ptr() - begin(); }
141 /// Return a pointer to the vector's buffer, even if empty().
142 pointer data() { return pointer(begin()); }
143 /// Return a pointer to the vector's buffer, even if empty().
144 const_pointer data() const { return const_pointer(begin()); }
146 LLVM_ATTRIBUTE_ALWAYS_INLINE
147 reference operator[](size_type idx) {
148 assert(idx < size());
151 LLVM_ATTRIBUTE_ALWAYS_INLINE
152 const_reference operator[](size_type idx) const {
153 assert(idx < size());
161 const_reference front() const {
170 const_reference back() const {
176 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
177 /// implementations that are designed to work with non-POD-like T's.
178 template <typename T, bool isPodLike>
179 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
181 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
183 static void destroy_range(T *S, T *E) {
190 /// Move the range [I, E) into the uninitialized memory starting with "Dest",
191 /// constructing elements as needed.
192 template<typename It1, typename It2>
193 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
194 std::uninitialized_copy(std::make_move_iterator(I),
195 std::make_move_iterator(E), Dest);
198 /// Copy the range [I, E) onto the uninitialized memory starting with "Dest",
199 /// constructing elements as needed.
200 template<typename It1, typename It2>
201 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
202 std::uninitialized_copy(I, E, Dest);
205 /// Grow the allocated memory (without initializing new elements), doubling
206 /// the size of the allocated memory. Guarantees space for at least one more
207 /// element, or MinSize more elements if specified.
208 void grow(size_t MinSize = 0);
211 void push_back(const T &Elt) {
212 if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
214 ::new ((void*) this->end()) T(Elt);
215 this->setEnd(this->end()+1);
218 void push_back(T &&Elt) {
219 if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
221 ::new ((void*) this->end()) T(::std::move(Elt));
222 this->setEnd(this->end()+1);
226 this->setEnd(this->end()-1);
231 // Define this out-of-line to dissuade the C++ compiler from inlining it.
232 template <typename T, bool isPodLike>
233 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
234 size_t CurCapacity = this->capacity();
235 size_t CurSize = this->size();
236 // Always grow, even from zero.
237 size_t NewCapacity = size_t(NextPowerOf2(CurCapacity+2));
238 if (NewCapacity < MinSize)
239 NewCapacity = MinSize;
240 T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));
242 // Move the elements over.
243 this->uninitialized_move(this->begin(), this->end(), NewElts);
245 // Destroy the original elements.
246 destroy_range(this->begin(), this->end());
248 // If this wasn't grown from the inline copy, deallocate the old space.
249 if (!this->isSmall())
252 this->setEnd(NewElts+CurSize);
253 this->BeginX = NewElts;
254 this->CapacityX = this->begin()+NewCapacity;
258 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
259 /// implementations that are designed to work with POD-like T's.
260 template <typename T>
261 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
263 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
265 // No need to do a destroy loop for POD's.
266 static void destroy_range(T *, T *) {}
268 /// Move the range [I, E) onto the uninitialized memory
269 /// starting with "Dest", constructing elements into it as needed.
270 template<typename It1, typename It2>
271 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
273 uninitialized_copy(I, E, Dest);
276 /// Copy the range [I, E) onto the uninitialized memory
277 /// starting with "Dest", constructing elements into it as needed.
278 template<typename It1, typename It2>
279 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
280 // Arbitrary iterator types; just use the basic implementation.
281 std::uninitialized_copy(I, E, Dest);
284 /// Copy the range [I, E) onto the uninitialized memory
285 /// starting with "Dest", constructing elements into it as needed.
286 template <typename T1, typename T2>
287 static void uninitialized_copy(
288 T1 *I, T1 *E, T2 *Dest,
289 typename std::enable_if<std::is_same<typename std::remove_const<T1>::type,
290 T2>::value>::type * = nullptr) {
291 // Use memcpy for PODs iterated by pointers (which includes SmallVector
292 // iterators): std::uninitialized_copy optimizes to memmove, but we can
293 // use memcpy here. Note that I and E are iterators and thus might be
294 // invalid for memcpy if they are equal.
296 memcpy(Dest, I, (E - I) * sizeof(T));
299 /// Double the size of the allocated memory, guaranteeing space for at
300 /// least one more element or MinSize if specified.
301 void grow(size_t MinSize = 0) {
302 this->grow_pod(MinSize*sizeof(T), sizeof(T));
306 void push_back(const T &Elt) {
307 if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
309 memcpy(this->end(), &Elt, sizeof(T));
310 this->setEnd(this->end()+1);
314 this->setEnd(this->end()-1);
318 /// This class consists of common code factored out of the SmallVector class to
319 /// reduce code duplication based on the SmallVector 'N' template parameter.
320 template <typename T>
321 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
322 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
325 typedef typename SuperClass::iterator iterator;
326 typedef typename SuperClass::const_iterator const_iterator;
327 typedef typename SuperClass::size_type size_type;
330 // Default ctor - Initialize to empty.
331 explicit SmallVectorImpl(unsigned N)
332 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
336 SmallVectorImpl(const SmallVectorImpl &) = delete;
339 // Destroy the constructed elements in the vector.
340 this->destroy_range(this->begin(), this->end());
342 // If this wasn't grown from the inline copy, deallocate the old space.
343 if (!this->isSmall())
348 this->destroy_range(this->begin(), this->end());
349 this->EndX = this->BeginX;
352 void resize(size_type N) {
353 if (N < this->size()) {
354 this->destroy_range(this->begin()+N, this->end());
355 this->setEnd(this->begin()+N);
356 } else if (N > this->size()) {
357 if (this->capacity() < N)
359 for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
361 this->setEnd(this->begin()+N);
365 void resize(size_type N, const T &NV) {
366 if (N < this->size()) {
367 this->destroy_range(this->begin()+N, this->end());
368 this->setEnd(this->begin()+N);
369 } else if (N > this->size()) {
370 if (this->capacity() < N)
372 std::uninitialized_fill(this->end(), this->begin()+N, NV);
373 this->setEnd(this->begin()+N);
377 void reserve(size_type N) {
378 if (this->capacity() < N)
382 LLVM_NODISCARD T pop_back_val() {
383 T Result = ::std::move(this->back());
388 void swap(SmallVectorImpl &RHS);
390 /// Add the specified range to the end of the SmallVector.
391 template<typename in_iter>
392 void append(in_iter in_start, in_iter in_end) {
393 size_type NumInputs = std::distance(in_start, in_end);
394 // Grow allocated space if needed.
395 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
396 this->grow(this->size()+NumInputs);
398 // Copy the new elements over.
399 this->uninitialized_copy(in_start, in_end, this->end());
400 this->setEnd(this->end() + NumInputs);
403 /// Add the specified range to the end of the SmallVector.
404 void append(size_type NumInputs, const T &Elt) {
405 // Grow allocated space if needed.
406 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
407 this->grow(this->size()+NumInputs);
409 // Copy the new elements over.
410 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
411 this->setEnd(this->end() + NumInputs);
414 void append(std::initializer_list<T> IL) {
415 append(IL.begin(), IL.end());
418 void assign(size_type NumElts, const T &Elt) {
420 if (this->capacity() < NumElts)
422 this->setEnd(this->begin()+NumElts);
423 std::uninitialized_fill(this->begin(), this->end(), Elt);
426 void assign(std::initializer_list<T> IL) {
431 iterator erase(const_iterator CI) {
432 // Just cast away constness because this is a non-const member function.
433 iterator I = const_cast<iterator>(CI);
435 assert(I >= this->begin() && "Iterator to erase is out of bounds.");
436 assert(I < this->end() && "Erasing at past-the-end iterator.");
439 // Shift all elts down one.
440 std::move(I+1, this->end(), I);
441 // Drop the last elt.
446 iterator erase(const_iterator CS, const_iterator CE) {
447 // Just cast away constness because this is a non-const member function.
448 iterator S = const_cast<iterator>(CS);
449 iterator E = const_cast<iterator>(CE);
451 assert(S >= this->begin() && "Range to erase is out of bounds.");
452 assert(S <= E && "Trying to erase invalid range.");
453 assert(E <= this->end() && "Trying to erase past the end.");
456 // Shift all elts down.
457 iterator I = std::move(E, this->end(), S);
458 // Drop the last elts.
459 this->destroy_range(I, this->end());
464 iterator insert(iterator I, T &&Elt) {
465 if (I == this->end()) { // Important special case for empty vector.
466 this->push_back(::std::move(Elt));
467 return this->end()-1;
470 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
471 assert(I <= this->end() && "Inserting past the end of the vector.");
473 if (this->EndX >= this->CapacityX) {
474 size_t EltNo = I-this->begin();
476 I = this->begin()+EltNo;
479 ::new ((void*) this->end()) T(::std::move(this->back()));
480 // Push everything else over.
481 std::move_backward(I, this->end()-1, this->end());
482 this->setEnd(this->end()+1);
484 // If we just moved the element we're inserting, be sure to update
487 if (I <= EltPtr && EltPtr < this->EndX)
490 *I = ::std::move(*EltPtr);
494 iterator insert(iterator I, const T &Elt) {
495 if (I == this->end()) { // Important special case for empty vector.
496 this->push_back(Elt);
497 return this->end()-1;
500 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
501 assert(I <= this->end() && "Inserting past the end of the vector.");
503 if (this->EndX >= this->CapacityX) {
504 size_t EltNo = I-this->begin();
506 I = this->begin()+EltNo;
508 ::new ((void*) this->end()) T(std::move(this->back()));
509 // Push everything else over.
510 std::move_backward(I, this->end()-1, this->end());
511 this->setEnd(this->end()+1);
513 // If we just moved the element we're inserting, be sure to update
515 const T *EltPtr = &Elt;
516 if (I <= EltPtr && EltPtr < this->EndX)
523 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
524 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
525 size_t InsertElt = I - this->begin();
527 if (I == this->end()) { // Important special case for empty vector.
528 append(NumToInsert, Elt);
529 return this->begin()+InsertElt;
532 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
533 assert(I <= this->end() && "Inserting past the end of the vector.");
535 // Ensure there is enough space.
536 reserve(this->size() + NumToInsert);
538 // Uninvalidate the iterator.
539 I = this->begin()+InsertElt;
541 // If there are more elements between the insertion point and the end of the
542 // range than there are being inserted, we can use a simple approach to
543 // insertion. Since we already reserved space, we know that this won't
544 // reallocate the vector.
545 if (size_t(this->end()-I) >= NumToInsert) {
546 T *OldEnd = this->end();
547 append(std::move_iterator<iterator>(this->end() - NumToInsert),
548 std::move_iterator<iterator>(this->end()));
550 // Copy the existing elements that get replaced.
551 std::move_backward(I, OldEnd-NumToInsert, OldEnd);
553 std::fill_n(I, NumToInsert, Elt);
557 // Otherwise, we're inserting more elements than exist already, and we're
558 // not inserting at the end.
560 // Move over the elements that we're about to overwrite.
561 T *OldEnd = this->end();
562 this->setEnd(this->end() + NumToInsert);
563 size_t NumOverwritten = OldEnd-I;
564 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
566 // Replace the overwritten part.
567 std::fill_n(I, NumOverwritten, Elt);
569 // Insert the non-overwritten middle part.
570 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
574 template<typename ItTy>
575 iterator insert(iterator I, ItTy From, ItTy To) {
576 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
577 size_t InsertElt = I - this->begin();
579 if (I == this->end()) { // Important special case for empty vector.
581 return this->begin()+InsertElt;
584 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
585 assert(I <= this->end() && "Inserting past the end of the vector.");
587 size_t NumToInsert = std::distance(From, To);
589 // Ensure there is enough space.
590 reserve(this->size() + NumToInsert);
592 // Uninvalidate the iterator.
593 I = this->begin()+InsertElt;
595 // If there are more elements between the insertion point and the end of the
596 // range than there are being inserted, we can use a simple approach to
597 // insertion. Since we already reserved space, we know that this won't
598 // reallocate the vector.
599 if (size_t(this->end()-I) >= NumToInsert) {
600 T *OldEnd = this->end();
601 append(std::move_iterator<iterator>(this->end() - NumToInsert),
602 std::move_iterator<iterator>(this->end()));
604 // Copy the existing elements that get replaced.
605 std::move_backward(I, OldEnd-NumToInsert, OldEnd);
607 std::copy(From, To, I);
611 // Otherwise, we're inserting more elements than exist already, and we're
612 // not inserting at the end.
614 // Move over the elements that we're about to overwrite.
615 T *OldEnd = this->end();
616 this->setEnd(this->end() + NumToInsert);
617 size_t NumOverwritten = OldEnd-I;
618 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
620 // Replace the overwritten part.
621 for (T *J = I; NumOverwritten > 0; --NumOverwritten) {
626 // Insert the non-overwritten middle part.
627 this->uninitialized_copy(From, To, OldEnd);
631 void insert(iterator I, std::initializer_list<T> IL) {
632 insert(I, IL.begin(), IL.end());
635 template <typename... ArgTypes> void emplace_back(ArgTypes &&... Args) {
636 if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
638 ::new ((void *)this->end()) T(std::forward<ArgTypes>(Args)...);
639 this->setEnd(this->end() + 1);
642 SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
644 SmallVectorImpl &operator=(SmallVectorImpl &&RHS);
646 bool operator==(const SmallVectorImpl &RHS) const {
647 if (this->size() != RHS.size()) return false;
648 return std::equal(this->begin(), this->end(), RHS.begin());
650 bool operator!=(const SmallVectorImpl &RHS) const {
651 return !(*this == RHS);
654 bool operator<(const SmallVectorImpl &RHS) const {
655 return std::lexicographical_compare(this->begin(), this->end(),
656 RHS.begin(), RHS.end());
659 /// Set the array size to \p N, which the current array must have enough
662 /// This does not construct or destroy any elements in the vector.
664 /// Clients can use this in conjunction with capacity() to write past the end
665 /// of the buffer when they know that more elements are available, and only
666 /// update the size later. This avoids the cost of value initializing elements
667 /// which will only be overwritten.
668 void set_size(size_type N) {
669 assert(N <= this->capacity());
670 this->setEnd(this->begin() + N);
674 template <typename T>
675 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
676 if (this == &RHS) return;
678 // We can only avoid copying elements if neither vector is small.
679 if (!this->isSmall() && !RHS.isSmall()) {
680 std::swap(this->BeginX, RHS.BeginX);
681 std::swap(this->EndX, RHS.EndX);
682 std::swap(this->CapacityX, RHS.CapacityX);
685 if (RHS.size() > this->capacity())
686 this->grow(RHS.size());
687 if (this->size() > RHS.capacity())
688 RHS.grow(this->size());
690 // Swap the shared elements.
691 size_t NumShared = this->size();
692 if (NumShared > RHS.size()) NumShared = RHS.size();
693 for (size_type i = 0; i != NumShared; ++i)
694 std::swap((*this)[i], RHS[i]);
696 // Copy over the extra elts.
697 if (this->size() > RHS.size()) {
698 size_t EltDiff = this->size() - RHS.size();
699 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
700 RHS.setEnd(RHS.end()+EltDiff);
701 this->destroy_range(this->begin()+NumShared, this->end());
702 this->setEnd(this->begin()+NumShared);
703 } else if (RHS.size() > this->size()) {
704 size_t EltDiff = RHS.size() - this->size();
705 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
706 this->setEnd(this->end() + EltDiff);
707 this->destroy_range(RHS.begin()+NumShared, RHS.end());
708 RHS.setEnd(RHS.begin()+NumShared);
712 template <typename T>
713 SmallVectorImpl<T> &SmallVectorImpl<T>::
714 operator=(const SmallVectorImpl<T> &RHS) {
715 // Avoid self-assignment.
716 if (this == &RHS) return *this;
718 // If we already have sufficient space, assign the common elements, then
719 // destroy any excess.
720 size_t RHSSize = RHS.size();
721 size_t CurSize = this->size();
722 if (CurSize >= RHSSize) {
723 // Assign common elements.
726 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
728 NewEnd = this->begin();
730 // Destroy excess elements.
731 this->destroy_range(NewEnd, this->end());
734 this->setEnd(NewEnd);
738 // If we have to grow to have enough elements, destroy the current elements.
739 // This allows us to avoid copying them during the grow.
740 // FIXME: don't do this if they're efficiently moveable.
741 if (this->capacity() < RHSSize) {
742 // Destroy current elements.
743 this->destroy_range(this->begin(), this->end());
744 this->setEnd(this->begin());
747 } else if (CurSize) {
748 // Otherwise, use assignment for the already-constructed elements.
749 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
752 // Copy construct the new elements in place.
753 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
754 this->begin()+CurSize);
757 this->setEnd(this->begin()+RHSSize);
761 template <typename T>
762 SmallVectorImpl<T> &SmallVectorImpl<T>::operator=(SmallVectorImpl<T> &&RHS) {
763 // Avoid self-assignment.
764 if (this == &RHS) return *this;
766 // If the RHS isn't small, clear this vector and then steal its buffer.
767 if (!RHS.isSmall()) {
768 this->destroy_range(this->begin(), this->end());
769 if (!this->isSmall()) free(this->begin());
770 this->BeginX = RHS.BeginX;
771 this->EndX = RHS.EndX;
772 this->CapacityX = RHS.CapacityX;
777 // If we already have sufficient space, assign the common elements, then
778 // destroy any excess.
779 size_t RHSSize = RHS.size();
780 size_t CurSize = this->size();
781 if (CurSize >= RHSSize) {
782 // Assign common elements.
783 iterator NewEnd = this->begin();
785 NewEnd = std::move(RHS.begin(), RHS.end(), NewEnd);
787 // Destroy excess elements and trim the bounds.
788 this->destroy_range(NewEnd, this->end());
789 this->setEnd(NewEnd);
797 // If we have to grow to have enough elements, destroy the current elements.
798 // This allows us to avoid copying them during the grow.
799 // FIXME: this may not actually make any sense if we can efficiently move
801 if (this->capacity() < RHSSize) {
802 // Destroy current elements.
803 this->destroy_range(this->begin(), this->end());
804 this->setEnd(this->begin());
807 } else if (CurSize) {
808 // Otherwise, use assignment for the already-constructed elements.
809 std::move(RHS.begin(), RHS.begin()+CurSize, this->begin());
812 // Move-construct the new elements in place.
813 this->uninitialized_move(RHS.begin()+CurSize, RHS.end(),
814 this->begin()+CurSize);
817 this->setEnd(this->begin()+RHSSize);
823 /// Storage for the SmallVector elements which aren't contained in
824 /// SmallVectorTemplateCommon. There are 'N-1' elements here. The remaining '1'
825 /// element is in the base class. This is specialized for the N=1 and N=0 cases
826 /// to avoid allocating unnecessary storage.
827 template <typename T, unsigned N>
828 struct SmallVectorStorage {
829 typename SmallVectorTemplateCommon<T>::U InlineElts[N - 1];
831 template <typename T> struct SmallVectorStorage<T, 1> {};
832 template <typename T> struct SmallVectorStorage<T, 0> {};
834 /// This is a 'vector' (really, a variable-sized array), optimized
835 /// for the case when the array is small. It contains some number of elements
836 /// in-place, which allows it to avoid heap allocation when the actual number of
837 /// elements is below that threshold. This allows normal "small" cases to be
838 /// fast without losing generality for large inputs.
840 /// Note that this does not attempt to be exception safe.
842 template <typename T, unsigned N>
843 class SmallVector : public SmallVectorImpl<T> {
844 /// Inline space for elements which aren't stored in the base class.
845 SmallVectorStorage<T, N> Storage;
848 SmallVector() : SmallVectorImpl<T>(N) {
851 explicit SmallVector(size_t Size, const T &Value = T())
852 : SmallVectorImpl<T>(N) {
853 this->assign(Size, Value);
856 template<typename ItTy>
857 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
861 template <typename RangeTy>
862 explicit SmallVector(const iterator_range<RangeTy> &R)
863 : SmallVectorImpl<T>(N) {
864 this->append(R.begin(), R.end());
867 SmallVector(std::initializer_list<T> IL) : SmallVectorImpl<T>(N) {
871 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(N) {
873 SmallVectorImpl<T>::operator=(RHS);
876 const SmallVector &operator=(const SmallVector &RHS) {
877 SmallVectorImpl<T>::operator=(RHS);
881 SmallVector(SmallVector &&RHS) : SmallVectorImpl<T>(N) {
883 SmallVectorImpl<T>::operator=(::std::move(RHS));
886 const SmallVector &operator=(SmallVector &&RHS) {
887 SmallVectorImpl<T>::operator=(::std::move(RHS));
891 SmallVector(SmallVectorImpl<T> &&RHS) : SmallVectorImpl<T>(N) {
893 SmallVectorImpl<T>::operator=(::std::move(RHS));
896 const SmallVector &operator=(SmallVectorImpl<T> &&RHS) {
897 SmallVectorImpl<T>::operator=(::std::move(RHS));
901 const SmallVector &operator=(std::initializer_list<T> IL) {
907 template<typename T, unsigned N>
908 static inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
909 return X.capacity_in_bytes();
912 } // end namespace llvm
916 /// Implement std::swap in terms of SmallVector swap.
919 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
923 /// Implement std::swap in terms of SmallVector swap.
924 template<typename T, unsigned N>
926 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {
930 } // end namespace std
932 #endif // LLVM_ADT_SMALLVECTOR_H