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/Support/AlignOf.h"
18 #include "llvm/Support/Compiler.h"
19 #include "llvm/Support/MathExtras.h"
20 #include "llvm/Support/type_traits.h"
31 /// SmallVectorBase - This is all the non-templated stuff common to all
33 class SmallVectorBase {
35 void *BeginX, *EndX, *CapacityX;
38 SmallVectorBase(void *FirstEl, size_t Size)
39 : BeginX(FirstEl), EndX(FirstEl), CapacityX((char*)FirstEl+Size) {}
41 /// grow_pod - This is an implementation of the grow() method which only works
42 /// on POD-like data types and is out of line to reduce code duplication.
43 void grow_pod(void *FirstEl, size_t MinSizeInBytes, size_t TSize);
46 /// size_in_bytes - This returns size()*sizeof(T).
47 size_t size_in_bytes() const {
48 return size_t((char*)EndX - (char*)BeginX);
51 /// capacity_in_bytes - This returns capacity()*sizeof(T).
52 size_t capacity_in_bytes() const {
53 return size_t((char*)CapacityX - (char*)BeginX);
56 bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const { return BeginX == EndX; }
59 template <typename T, unsigned N> struct SmallVectorStorage;
61 /// SmallVectorTemplateCommon - This is the part of SmallVectorTemplateBase
62 /// which does not depend on whether the type T is a POD. The extra dummy
63 /// template argument is used by ArrayRef to avoid unnecessarily requiring T
65 template <typename T, typename = void>
66 class SmallVectorTemplateCommon : public SmallVectorBase {
68 template <typename, unsigned> friend struct SmallVectorStorage;
70 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
71 // don't want it to be automatically run, so we need to represent the space as
72 // something else. Use an array of char of sufficient alignment.
73 typedef llvm::AlignedCharArrayUnion<T> U;
75 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
78 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(&FirstEl, Size) {}
80 void grow_pod(size_t MinSizeInBytes, size_t TSize) {
81 SmallVectorBase::grow_pod(&FirstEl, MinSizeInBytes, TSize);
84 /// isSmall - Return true if this is a smallvector which has not had dynamic
85 /// memory allocated for it.
86 bool isSmall() const {
87 return BeginX == static_cast<const void*>(&FirstEl);
90 /// resetToSmall - Put this vector in a state of being small.
92 BeginX = EndX = CapacityX = &FirstEl;
95 void setEnd(T *P) { this->EndX = P; }
97 typedef size_t size_type;
98 typedef ptrdiff_t difference_type;
101 typedef const T *const_iterator;
103 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
104 typedef std::reverse_iterator<iterator> reverse_iterator;
106 typedef T &reference;
107 typedef const T &const_reference;
109 typedef const T *const_pointer;
111 // forward iterator creation methods.
112 iterator begin() { return (iterator)this->BeginX; }
113 const_iterator begin() const { return (const_iterator)this->BeginX; }
114 iterator end() { return (iterator)this->EndX; }
115 const_iterator end() const { return (const_iterator)this->EndX; }
117 iterator capacity_ptr() { return (iterator)this->CapacityX; }
118 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
121 // reverse iterator creation methods.
122 reverse_iterator rbegin() { return reverse_iterator(end()); }
123 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
124 reverse_iterator rend() { return reverse_iterator(begin()); }
125 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
127 size_type size() const { return end()-begin(); }
128 size_type max_size() const { return size_type(-1) / sizeof(T); }
130 /// capacity - Return the total number of elements in the currently allocated
132 size_t capacity() const { return capacity_ptr() - begin(); }
134 /// data - Return a pointer to the vector's buffer, even if empty().
135 pointer data() { return pointer(begin()); }
136 /// data - Return a pointer to the vector's buffer, even if empty().
137 const_pointer data() const { return const_pointer(begin()); }
139 reference operator[](unsigned idx) {
140 assert(begin() + idx < end());
143 const_reference operator[](unsigned idx) const {
144 assert(begin() + idx < end());
152 const_reference front() const {
161 const_reference back() const {
167 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
168 /// implementations that are designed to work with non-POD-like T's.
169 template <typename T, bool isPodLike>
170 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
172 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
174 static void destroy_range(T *S, T *E) {
181 /// move - Use move-assignment to move the range [I, E) onto the
182 /// objects starting with "Dest". This is just <memory>'s
183 /// std::move, but not all stdlibs actually provide that.
184 template<typename It1, typename It2>
185 static It2 move(It1 I, It1 E, It2 Dest) {
186 for (; I != E; ++I, ++Dest)
187 *Dest = ::std::move(*I);
191 /// move_backward - Use move-assignment to move the range
192 /// [I, E) onto the objects ending at "Dest", moving objects
193 /// in reverse order. This is just <algorithm>'s
194 /// std::move_backward, but not all stdlibs actually provide that.
195 template<typename It1, typename It2>
196 static It2 move_backward(It1 I, It1 E, It2 Dest) {
198 *--Dest = ::std::move(*--E);
202 /// uninitialized_move - Move the range [I, E) into the uninitialized
203 /// memory starting with "Dest", constructing elements as needed.
204 template<typename It1, typename It2>
205 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
206 for (; I != E; ++I, ++Dest)
207 ::new ((void*) &*Dest) T(::std::move(*I));
210 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized
211 /// memory starting with "Dest", constructing elements as needed.
212 template<typename It1, typename It2>
213 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
214 std::uninitialized_copy(I, E, Dest);
217 /// grow - Grow the allocated memory (without initializing new
218 /// elements), doubling the size of the allocated memory.
219 /// Guarantees space for at least one more element, or MinSize more
220 /// elements if specified.
221 void grow(size_t MinSize = 0);
224 void push_back(const T &Elt) {
225 if (this->EndX < this->CapacityX) {
227 ::new ((void*) this->end()) T(Elt);
228 this->setEnd(this->end()+1);
235 void push_back(T &&Elt) {
236 if (this->EndX < this->CapacityX) {
238 ::new ((void*) this->end()) T(::std::move(Elt));
239 this->setEnd(this->end()+1);
247 this->setEnd(this->end()-1);
252 // Define this out-of-line to dissuade the C++ compiler from inlining it.
253 template <typename T, bool isPodLike>
254 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
255 size_t CurCapacity = this->capacity();
256 size_t CurSize = this->size();
257 // Always grow, even from zero.
258 size_t NewCapacity = size_t(NextPowerOf2(CurCapacity+2));
259 if (NewCapacity < MinSize)
260 NewCapacity = MinSize;
261 T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));
263 // Move the elements over.
264 this->uninitialized_move(this->begin(), this->end(), NewElts);
266 // Destroy the original elements.
267 destroy_range(this->begin(), this->end());
269 // If this wasn't grown from the inline copy, deallocate the old space.
270 if (!this->isSmall())
273 this->setEnd(NewElts+CurSize);
274 this->BeginX = NewElts;
275 this->CapacityX = this->begin()+NewCapacity;
279 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
280 /// implementations that are designed to work with POD-like T's.
281 template <typename T>
282 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
284 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
286 // No need to do a destroy loop for POD's.
287 static void destroy_range(T *, T *) {}
289 /// move - Use move-assignment to move the range [I, E) onto the
290 /// objects starting with "Dest". For PODs, this is just memcpy.
291 template<typename It1, typename It2>
292 static It2 move(It1 I, It1 E, It2 Dest) {
293 return ::std::copy(I, E, Dest);
296 /// move_backward - Use move-assignment to move the range
297 /// [I, E) onto the objects ending at "Dest", moving objects
298 /// in reverse order.
299 template<typename It1, typename It2>
300 static It2 move_backward(It1 I, It1 E, It2 Dest) {
301 return ::std::copy_backward(I, E, Dest);
304 /// uninitialized_move - Move the range [I, E) onto the uninitialized memory
305 /// starting with "Dest", constructing elements into it as needed.
306 template<typename It1, typename It2>
307 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
309 uninitialized_copy(I, E, Dest);
312 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
313 /// starting with "Dest", constructing elements into it as needed.
314 template<typename It1, typename It2>
315 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
316 // Arbitrary iterator types; just use the basic implementation.
317 std::uninitialized_copy(I, E, Dest);
320 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
321 /// starting with "Dest", constructing elements into it as needed.
322 template<typename T1, typename T2>
323 static void uninitialized_copy(T1 *I, T1 *E, T2 *Dest) {
324 // Use memcpy for PODs iterated by pointers (which includes SmallVector
325 // iterators): std::uninitialized_copy optimizes to memmove, but we can
327 memcpy(Dest, I, (E-I)*sizeof(T));
330 /// grow - double the size of the allocated memory, guaranteeing space for at
331 /// least one more element or MinSize if specified.
332 void grow(size_t MinSize = 0) {
333 this->grow_pod(MinSize*sizeof(T), sizeof(T));
336 void push_back(const T &Elt) {
337 if (this->EndX < this->CapacityX) {
339 memcpy(this->end(), &Elt, sizeof(T));
340 this->setEnd(this->end()+1);
348 this->setEnd(this->end()-1);
353 /// SmallVectorImpl - This class consists of common code factored out of the
354 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
355 /// template parameter.
356 template <typename T>
357 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
358 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
360 SmallVectorImpl(const SmallVectorImpl&) LLVM_DELETED_FUNCTION;
362 typedef typename SuperClass::iterator iterator;
363 typedef typename SuperClass::size_type size_type;
366 // Default ctor - Initialize to empty.
367 explicit SmallVectorImpl(unsigned N)
368 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
373 // Destroy the constructed elements in the vector.
374 this->destroy_range(this->begin(), this->end());
376 // If this wasn't grown from the inline copy, deallocate the old space.
377 if (!this->isSmall())
383 this->destroy_range(this->begin(), this->end());
384 this->EndX = this->BeginX;
387 void resize(unsigned N) {
388 if (N < this->size()) {
389 this->destroy_range(this->begin()+N, this->end());
390 this->setEnd(this->begin()+N);
391 } else if (N > this->size()) {
392 if (this->capacity() < N)
394 std::uninitialized_fill(this->end(), this->begin()+N, T());
395 this->setEnd(this->begin()+N);
399 void resize(unsigned N, const T &NV) {
400 if (N < this->size()) {
401 this->destroy_range(this->begin()+N, this->end());
402 this->setEnd(this->begin()+N);
403 } else if (N > this->size()) {
404 if (this->capacity() < N)
406 std::uninitialized_fill(this->end(), this->begin()+N, NV);
407 this->setEnd(this->begin()+N);
411 void reserve(unsigned N) {
412 if (this->capacity() < N)
416 T LLVM_ATTRIBUTE_UNUSED_RESULT pop_back_val() {
417 T Result = ::std::move(this->back());
422 void swap(SmallVectorImpl &RHS);
424 /// append - Add the specified range to the end of the SmallVector.
426 template<typename in_iter>
427 void append(in_iter in_start, in_iter in_end) {
428 size_type NumInputs = std::distance(in_start, in_end);
429 // Grow allocated space if needed.
430 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
431 this->grow(this->size()+NumInputs);
433 // Copy the new elements over.
434 // TODO: NEED To compile time dispatch on whether in_iter is a random access
435 // iterator to use the fast uninitialized_copy.
436 std::uninitialized_copy(in_start, in_end, this->end());
437 this->setEnd(this->end() + NumInputs);
440 /// append - Add the specified range to the end of the SmallVector.
442 void append(size_type NumInputs, const T &Elt) {
443 // Grow allocated space if needed.
444 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
445 this->grow(this->size()+NumInputs);
447 // Copy the new elements over.
448 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
449 this->setEnd(this->end() + NumInputs);
452 void assign(unsigned NumElts, const T &Elt) {
454 append(NumElts, Elt);
457 template <typename in_iter> void assign(in_iter S, in_iter E) {
462 iterator erase(iterator I) {
463 assert(I >= this->begin() && "Iterator to erase is out of bounds.");
464 assert(I < this->end() && "Erasing at past-the-end iterator.");
467 // Shift all elts down one.
468 this->move(I+1, this->end(), I);
469 // Drop the last elt.
474 iterator erase(iterator S, iterator E) {
475 assert(S >= this->begin() && "Range to erase is out of bounds.");
476 assert(S <= E && "Trying to erase invalid range.");
477 assert(E <= this->end() && "Trying to erase past the end.");
480 // Shift all elts down.
481 iterator I = this->move(E, this->end(), S);
482 // Drop the last elts.
483 this->destroy_range(I, this->end());
488 iterator insert(iterator I, T &&Elt) {
489 if (I == this->end()) { // Important special case for empty vector.
490 this->push_back(::std::move(Elt));
491 return this->end()-1;
494 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
495 assert(I <= this->end() && "Inserting past the end of the vector.");
497 if (this->EndX < this->CapacityX) {
499 ::new ((void*) this->end()) T(::std::move(this->back()));
500 this->setEnd(this->end()+1);
501 // Push everything else over.
502 this->move_backward(I, this->end()-1, this->end());
504 // If we just moved the element we're inserting, be sure to update
507 if (I <= EltPtr && EltPtr < this->EndX)
510 *I = ::std::move(*EltPtr);
513 size_t EltNo = I-this->begin();
515 I = this->begin()+EltNo;
519 iterator insert(iterator I, const T &Elt) {
520 if (I == this->end()) { // Important special case for empty vector.
521 this->push_back(Elt);
522 return this->end()-1;
525 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
526 assert(I <= this->end() && "Inserting past the end of the vector.");
528 if (this->EndX < this->CapacityX) {
530 ::new ((void*) this->end()) T(this->back());
531 this->setEnd(this->end()+1);
532 // Push everything else over.
533 this->move_backward(I, this->end()-1, this->end());
535 // If we just moved the element we're inserting, be sure to update
537 const T *EltPtr = &Elt;
538 if (I <= EltPtr && EltPtr < this->EndX)
544 size_t EltNo = I-this->begin();
546 I = this->begin()+EltNo;
550 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
551 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
552 size_t InsertElt = I - this->begin();
554 if (I == this->end()) { // Important special case for empty vector.
555 append(NumToInsert, Elt);
556 return this->begin()+InsertElt;
559 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
560 assert(I <= this->end() && "Inserting past the end of the vector.");
562 // Ensure there is enough space.
563 reserve(static_cast<unsigned>(this->size() + NumToInsert));
565 // Uninvalidate the iterator.
566 I = this->begin()+InsertElt;
568 // If there are more elements between the insertion point and the end of the
569 // range than there are being inserted, we can use a simple approach to
570 // insertion. Since we already reserved space, we know that this won't
571 // reallocate the vector.
572 if (size_t(this->end()-I) >= NumToInsert) {
573 T *OldEnd = this->end();
574 append(this->end()-NumToInsert, this->end());
576 // Copy the existing elements that get replaced.
577 this->move_backward(I, OldEnd-NumToInsert, OldEnd);
579 std::fill_n(I, NumToInsert, Elt);
583 // Otherwise, we're inserting more elements than exist already, and we're
584 // not inserting at the end.
586 // Move over the elements that we're about to overwrite.
587 T *OldEnd = this->end();
588 this->setEnd(this->end() + NumToInsert);
589 size_t NumOverwritten = OldEnd-I;
590 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
592 // Replace the overwritten part.
593 std::fill_n(I, NumOverwritten, Elt);
595 // Insert the non-overwritten middle part.
596 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
600 template<typename ItTy>
601 iterator insert(iterator I, ItTy From, ItTy To) {
602 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
603 size_t InsertElt = I - this->begin();
605 if (I == this->end()) { // Important special case for empty vector.
607 return this->begin()+InsertElt;
610 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
611 assert(I <= this->end() && "Inserting past the end of the vector.");
613 size_t NumToInsert = std::distance(From, To);
615 // Ensure there is enough space.
616 reserve(static_cast<unsigned>(this->size() + NumToInsert));
618 // Uninvalidate the iterator.
619 I = this->begin()+InsertElt;
621 // If there are more elements between the insertion point and the end of the
622 // range than there are being inserted, we can use a simple approach to
623 // insertion. Since we already reserved space, we know that this won't
624 // reallocate the vector.
625 if (size_t(this->end()-I) >= NumToInsert) {
626 T *OldEnd = this->end();
627 append(this->end()-NumToInsert, this->end());
629 // Copy the existing elements that get replaced.
630 this->move_backward(I, OldEnd-NumToInsert, OldEnd);
632 std::copy(From, To, I);
636 // Otherwise, we're inserting more elements than exist already, and we're
637 // not inserting at the end.
639 // Move over the elements that we're about to overwrite.
640 T *OldEnd = this->end();
641 this->setEnd(this->end() + NumToInsert);
642 size_t NumOverwritten = OldEnd-I;
643 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
645 // Replace the overwritten part.
646 for (T *J = I; NumOverwritten > 0; --NumOverwritten) {
651 // Insert the non-overwritten middle part.
652 this->uninitialized_copy(From, To, OldEnd);
656 SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
658 SmallVectorImpl &operator=(SmallVectorImpl &&RHS);
660 bool operator==(const SmallVectorImpl &RHS) const {
661 if (this->size() != RHS.size()) return false;
662 return std::equal(this->begin(), this->end(), RHS.begin());
664 bool operator!=(const SmallVectorImpl &RHS) const {
665 return !(*this == RHS);
668 bool operator<(const SmallVectorImpl &RHS) const {
669 return std::lexicographical_compare(this->begin(), this->end(),
670 RHS.begin(), RHS.end());
673 /// Set the array size to \p N, which the current array must have enough
676 /// This does not construct or destroy any elements in the vector.
678 /// Clients can use this in conjunction with capacity() to write past the end
679 /// of the buffer when they know that more elements are available, and only
680 /// update the size later. This avoids the cost of value initializing elements
681 /// which will only be overwritten.
682 void set_size(unsigned N) {
683 assert(N <= this->capacity());
684 this->setEnd(this->begin() + N);
689 template <typename T>
690 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
691 if (this == &RHS) return;
693 // We can only avoid copying elements if neither vector is small.
694 if (!this->isSmall() && !RHS.isSmall()) {
695 std::swap(this->BeginX, RHS.BeginX);
696 std::swap(this->EndX, RHS.EndX);
697 std::swap(this->CapacityX, RHS.CapacityX);
700 if (RHS.size() > this->capacity())
701 this->grow(RHS.size());
702 if (this->size() > RHS.capacity())
703 RHS.grow(this->size());
705 // Swap the shared elements.
706 size_t NumShared = this->size();
707 if (NumShared > RHS.size()) NumShared = RHS.size();
708 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
709 std::swap((*this)[i], RHS[i]);
711 // Copy over the extra elts.
712 if (this->size() > RHS.size()) {
713 size_t EltDiff = this->size() - RHS.size();
714 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
715 RHS.setEnd(RHS.end()+EltDiff);
716 this->destroy_range(this->begin()+NumShared, this->end());
717 this->setEnd(this->begin()+NumShared);
718 } else if (RHS.size() > this->size()) {
719 size_t EltDiff = RHS.size() - this->size();
720 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
721 this->setEnd(this->end() + EltDiff);
722 this->destroy_range(RHS.begin()+NumShared, RHS.end());
723 RHS.setEnd(RHS.begin()+NumShared);
727 template <typename T>
728 SmallVectorImpl<T> &SmallVectorImpl<T>::
729 operator=(const SmallVectorImpl<T> &RHS) {
730 // Avoid self-assignment.
731 if (this == &RHS) return *this;
733 // If we already have sufficient space, assign the common elements, then
734 // destroy any excess.
735 size_t RHSSize = RHS.size();
736 size_t CurSize = this->size();
737 if (CurSize >= RHSSize) {
738 // Assign common elements.
741 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
743 NewEnd = this->begin();
745 // Destroy excess elements.
746 this->destroy_range(NewEnd, this->end());
749 this->setEnd(NewEnd);
753 // If we have to grow to have enough elements, destroy the current elements.
754 // This allows us to avoid copying them during the grow.
755 // FIXME: don't do this if they're efficiently moveable.
756 if (this->capacity() < RHSSize) {
757 // Destroy current elements.
758 this->destroy_range(this->begin(), this->end());
759 this->setEnd(this->begin());
762 } else if (CurSize) {
763 // Otherwise, use assignment for the already-constructed elements.
764 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
767 // Copy construct the new elements in place.
768 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
769 this->begin()+CurSize);
772 this->setEnd(this->begin()+RHSSize);
776 template <typename T>
777 SmallVectorImpl<T> &SmallVectorImpl<T>::operator=(SmallVectorImpl<T> &&RHS) {
778 // Avoid self-assignment.
779 if (this == &RHS) return *this;
781 // If the RHS isn't small, clear this vector and then steal its buffer.
782 if (!RHS.isSmall()) {
783 this->destroy_range(this->begin(), this->end());
784 if (!this->isSmall()) free(this->begin());
785 this->BeginX = RHS.BeginX;
786 this->EndX = RHS.EndX;
787 this->CapacityX = RHS.CapacityX;
792 // If we already have sufficient space, assign the common elements, then
793 // destroy any excess.
794 size_t RHSSize = RHS.size();
795 size_t CurSize = this->size();
796 if (CurSize >= RHSSize) {
797 // Assign common elements.
798 iterator NewEnd = this->begin();
800 NewEnd = this->move(RHS.begin(), RHS.end(), NewEnd);
802 // Destroy excess elements and trim the bounds.
803 this->destroy_range(NewEnd, this->end());
804 this->setEnd(NewEnd);
812 // If we have to grow to have enough elements, destroy the current elements.
813 // This allows us to avoid copying them during the grow.
814 // FIXME: this may not actually make any sense if we can efficiently move
816 if (this->capacity() < RHSSize) {
817 // Destroy current elements.
818 this->destroy_range(this->begin(), this->end());
819 this->setEnd(this->begin());
822 } else if (CurSize) {
823 // Otherwise, use assignment for the already-constructed elements.
824 this->move(RHS.begin(), RHS.end(), this->begin());
827 // Move-construct the new elements in place.
828 this->uninitialized_move(RHS.begin()+CurSize, RHS.end(),
829 this->begin()+CurSize);
832 this->setEnd(this->begin()+RHSSize);
838 /// Storage for the SmallVector elements which aren't contained in
839 /// SmallVectorTemplateCommon. There are 'N-1' elements here. The remaining '1'
840 /// element is in the base class. This is specialized for the N=1 and N=0 cases
841 /// to avoid allocating unnecessary storage.
842 template <typename T, unsigned N>
843 struct SmallVectorStorage {
844 typename SmallVectorTemplateCommon<T>::U InlineElts[N - 1];
846 template <typename T> struct SmallVectorStorage<T, 1> {};
847 template <typename T> struct SmallVectorStorage<T, 0> {};
849 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
850 /// for the case when the array is small. It contains some number of elements
851 /// in-place, which allows it to avoid heap allocation when the actual number of
852 /// elements is below that threshold. This allows normal "small" cases to be
853 /// fast without losing generality for large inputs.
855 /// Note that this does not attempt to be exception safe.
857 template <typename T, unsigned N>
858 class SmallVector : public SmallVectorImpl<T> {
859 /// Storage - Inline space for elements which aren't stored in the base class.
860 SmallVectorStorage<T, N> Storage;
862 SmallVector() : SmallVectorImpl<T>(N) {
865 explicit SmallVector(unsigned Size, const T &Value = T())
866 : SmallVectorImpl<T>(N) {
867 this->assign(Size, Value);
870 template<typename ItTy>
871 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
875 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(N) {
877 SmallVectorImpl<T>::operator=(RHS);
880 const SmallVector &operator=(const SmallVector &RHS) {
881 SmallVectorImpl<T>::operator=(RHS);
885 SmallVector(SmallVector &&RHS) : SmallVectorImpl<T>(N) {
887 SmallVectorImpl<T>::operator=(::std::move(RHS));
890 const SmallVector &operator=(SmallVector &&RHS) {
891 SmallVectorImpl<T>::operator=(::std::move(RHS));
896 template<typename T, unsigned N>
897 static inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
898 return X.capacity_in_bytes();
901 } // End llvm namespace
904 /// Implement std::swap in terms of SmallVector swap.
907 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
911 /// Implement std::swap in terms of SmallVector swap.
912 template<typename T, unsigned N>
914 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {