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"
32 /// This is all the non-templated stuff common to all SmallVectors.
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 /// 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 /// 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 /// This is the part of SmallVectorTemplateBase which does not depend on whether
62 /// the type T is a POD. The extra dummy template argument is used by ArrayRef
63 /// to avoid unnecessarily requiring T to be complete.
64 template <typename T, typename = void>
65 class SmallVectorTemplateCommon : public SmallVectorBase {
67 template <typename, unsigned> friend struct SmallVectorStorage;
69 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
70 // don't want it to be automatically run, so we need to represent the space as
71 // something else. Use an array of char of sufficient alignment.
72 typedef llvm::AlignedCharArrayUnion<T> U;
74 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
77 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(&FirstEl, Size) {}
79 void grow_pod(size_t MinSizeInBytes, size_t TSize) {
80 SmallVectorBase::grow_pod(&FirstEl, MinSizeInBytes, TSize);
83 /// Return true if this is a smallvector which has not had dynamic
84 /// memory allocated for it.
85 bool isSmall() const {
86 return BeginX == static_cast<const void*>(&FirstEl);
89 /// Put this vector in a state of being small.
91 BeginX = EndX = CapacityX = &FirstEl;
94 void setEnd(T *P) { this->EndX = P; }
96 typedef size_t size_type;
97 typedef ptrdiff_t difference_type;
100 typedef const T *const_iterator;
102 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
103 typedef std::reverse_iterator<iterator> reverse_iterator;
105 typedef T &reference;
106 typedef const T &const_reference;
108 typedef const T *const_pointer;
110 // forward iterator creation methods.
111 iterator begin() { return (iterator)this->BeginX; }
112 const_iterator begin() const { return (const_iterator)this->BeginX; }
113 iterator end() { return (iterator)this->EndX; }
114 const_iterator end() const { return (const_iterator)this->EndX; }
116 iterator capacity_ptr() { return (iterator)this->CapacityX; }
117 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
120 // reverse iterator creation methods.
121 reverse_iterator rbegin() { return reverse_iterator(end()); }
122 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
123 reverse_iterator rend() { return reverse_iterator(begin()); }
124 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
126 size_type size() const { return end()-begin(); }
127 size_type max_size() const { return size_type(-1) / sizeof(T); }
129 /// Return the total number of elements in the currently allocated buffer.
130 size_t capacity() const { return capacity_ptr() - begin(); }
132 /// Return a pointer to the vector's buffer, even if empty().
133 pointer data() { return pointer(begin()); }
134 /// Return a pointer to the vector's buffer, even if empty().
135 const_pointer data() const { return const_pointer(begin()); }
137 reference operator[](size_type idx) {
138 assert(begin() + idx < end());
141 const_reference operator[](size_type idx) const {
142 assert(begin() + idx < end());
150 const_reference front() const {
159 const_reference back() const {
165 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
166 /// implementations that are designed to work with non-POD-like T's.
167 template <typename T, bool isPodLike>
168 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
170 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
172 static void destroy_range(T *S, T *E) {
179 /// Use move-assignment to move the range [I, E) onto the
180 /// objects starting with "Dest". This is just <memory>'s
181 /// std::move, but not all stdlibs actually provide that.
182 template<typename It1, typename It2>
183 static It2 move(It1 I, It1 E, It2 Dest) {
184 for (; I != E; ++I, ++Dest)
185 *Dest = ::std::move(*I);
189 /// Use move-assignment to move the range
190 /// [I, E) onto the objects ending at "Dest", moving objects
191 /// in reverse order. This is just <algorithm>'s
192 /// std::move_backward, but not all stdlibs actually provide that.
193 template<typename It1, typename It2>
194 static It2 move_backward(It1 I, It1 E, It2 Dest) {
196 *--Dest = ::std::move(*--E);
200 /// Move the range [I, E) into the uninitialized memory starting with "Dest",
201 /// constructing elements as needed.
202 template<typename It1, typename It2>
203 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
204 for (; I != E; ++I, ++Dest)
205 ::new ((void*) &*Dest) T(::std::move(*I));
208 /// Copy the range [I, E) onto the uninitialized memory starting with "Dest",
209 /// constructing elements as needed.
210 template<typename It1, typename It2>
211 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
212 std::uninitialized_copy(I, E, Dest);
215 /// Grow the allocated memory (without initializing new elements), doubling
216 /// the size of the allocated memory. Guarantees space for at least one more
217 /// element, or MinSize more elements if specified.
218 void grow(size_t MinSize = 0);
221 void push_back(const T &Elt) {
222 if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
224 ::new ((void*) this->end()) T(Elt);
225 this->setEnd(this->end()+1);
228 void push_back(T &&Elt) {
229 if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
231 ::new ((void*) this->end()) T(::std::move(Elt));
232 this->setEnd(this->end()+1);
236 this->setEnd(this->end()-1);
241 // Define this out-of-line to dissuade the C++ compiler from inlining it.
242 template <typename T, bool isPodLike>
243 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
244 size_t CurCapacity = this->capacity();
245 size_t CurSize = this->size();
246 // Always grow, even from zero.
247 size_t NewCapacity = size_t(NextPowerOf2(CurCapacity+2));
248 if (NewCapacity < MinSize)
249 NewCapacity = MinSize;
250 T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));
252 // Move the elements over.
253 this->uninitialized_move(this->begin(), this->end(), NewElts);
255 // Destroy the original elements.
256 destroy_range(this->begin(), this->end());
258 // If this wasn't grown from the inline copy, deallocate the old space.
259 if (!this->isSmall())
262 this->setEnd(NewElts+CurSize);
263 this->BeginX = NewElts;
264 this->CapacityX = this->begin()+NewCapacity;
268 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
269 /// implementations that are designed to work with POD-like T's.
270 template <typename T>
271 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
273 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
275 // No need to do a destroy loop for POD's.
276 static void destroy_range(T *, T *) {}
278 /// Use move-assignment to move the range [I, E) onto the
279 /// objects starting with "Dest". For PODs, this is just memcpy.
280 template<typename It1, typename It2>
281 static It2 move(It1 I, It1 E, It2 Dest) {
282 return ::std::copy(I, E, Dest);
285 /// Use move-assignment to move the range [I, E) onto the objects ending at
286 /// "Dest", moving objects in reverse order.
287 template<typename It1, typename It2>
288 static It2 move_backward(It1 I, It1 E, It2 Dest) {
289 return ::std::copy_backward(I, E, Dest);
292 /// Move the range [I, E) onto the uninitialized memory
293 /// starting with "Dest", constructing elements into it as needed.
294 template<typename It1, typename It2>
295 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
297 uninitialized_copy(I, E, Dest);
300 /// Copy the range [I, E) onto the uninitialized memory
301 /// starting with "Dest", constructing elements into it as needed.
302 template<typename It1, typename It2>
303 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
304 // Arbitrary iterator types; just use the basic implementation.
305 std::uninitialized_copy(I, E, Dest);
308 /// Copy the range [I, E) onto the uninitialized memory
309 /// starting with "Dest", constructing elements into it as needed.
310 template<typename T1, typename T2>
311 static void uninitialized_copy(T1 *I, T1 *E, T2 *Dest) {
312 // Use memcpy for PODs iterated by pointers (which includes SmallVector
313 // iterators): std::uninitialized_copy optimizes to memmove, but we can
315 memcpy(Dest, I, (E-I)*sizeof(T));
318 /// Double the size of the allocated memory, guaranteeing space for at
319 /// least one more element or MinSize if specified.
320 void grow(size_t MinSize = 0) {
321 this->grow_pod(MinSize*sizeof(T), sizeof(T));
324 void push_back(const T &Elt) {
325 if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
327 memcpy(this->end(), &Elt, sizeof(T));
328 this->setEnd(this->end()+1);
332 this->setEnd(this->end()-1);
337 /// This class consists of common code factored out of the SmallVector class to
338 /// reduce code duplication based on the SmallVector 'N' template parameter.
339 template <typename T>
340 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
341 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
343 SmallVectorImpl(const SmallVectorImpl&) LLVM_DELETED_FUNCTION;
345 typedef typename SuperClass::iterator iterator;
346 typedef typename SuperClass::size_type size_type;
349 // Default ctor - Initialize to empty.
350 explicit SmallVectorImpl(unsigned N)
351 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
356 // Destroy the constructed elements in the vector.
357 this->destroy_range(this->begin(), this->end());
359 // If this wasn't grown from the inline copy, deallocate the old space.
360 if (!this->isSmall())
366 this->destroy_range(this->begin(), this->end());
367 this->EndX = this->BeginX;
370 void resize(unsigned N) {
371 if (N < this->size()) {
372 this->destroy_range(this->begin()+N, this->end());
373 this->setEnd(this->begin()+N);
374 } else if (N > this->size()) {
375 if (this->capacity() < N)
377 for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
379 this->setEnd(this->begin()+N);
383 void resize(unsigned N, const T &NV) {
384 if (N < this->size()) {
385 this->destroy_range(this->begin()+N, this->end());
386 this->setEnd(this->begin()+N);
387 } else if (N > this->size()) {
388 if (this->capacity() < N)
390 std::uninitialized_fill(this->end(), this->begin()+N, NV);
391 this->setEnd(this->begin()+N);
395 void reserve(unsigned N) {
396 if (this->capacity() < N)
400 T LLVM_ATTRIBUTE_UNUSED_RESULT pop_back_val() {
401 T Result = ::std::move(this->back());
406 void swap(SmallVectorImpl &RHS);
408 /// Add the specified range to the end of the SmallVector.
409 template<typename in_iter>
410 void append(in_iter in_start, in_iter in_end) {
411 size_type NumInputs = std::distance(in_start, in_end);
412 // Grow allocated space if needed.
413 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
414 this->grow(this->size()+NumInputs);
416 // Copy the new elements over.
417 // TODO: NEED To compile time dispatch on whether in_iter is a random access
418 // iterator to use the fast uninitialized_copy.
419 std::uninitialized_copy(in_start, in_end, this->end());
420 this->setEnd(this->end() + NumInputs);
423 /// Add the specified range to the end of the SmallVector.
424 void append(size_type NumInputs, const T &Elt) {
425 // Grow allocated space if needed.
426 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
427 this->grow(this->size()+NumInputs);
429 // Copy the new elements over.
430 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
431 this->setEnd(this->end() + NumInputs);
434 void assign(unsigned NumElts, const T &Elt) {
436 if (this->capacity() < NumElts)
438 this->setEnd(this->begin()+NumElts);
439 std::uninitialized_fill(this->begin(), this->end(), Elt);
442 iterator erase(iterator I) {
443 assert(I >= this->begin() && "Iterator to erase is out of bounds.");
444 assert(I < this->end() && "Erasing at past-the-end iterator.");
447 // Shift all elts down one.
448 this->move(I+1, this->end(), I);
449 // Drop the last elt.
454 iterator erase(iterator S, iterator E) {
455 assert(S >= this->begin() && "Range to erase is out of bounds.");
456 assert(S <= E && "Trying to erase invalid range.");
457 assert(E <= this->end() && "Trying to erase past the end.");
460 // Shift all elts down.
461 iterator I = this->move(E, this->end(), S);
462 // Drop the last elts.
463 this->destroy_range(I, this->end());
468 iterator insert(iterator I, T &&Elt) {
469 if (I == this->end()) { // Important special case for empty vector.
470 this->push_back(::std::move(Elt));
471 return this->end()-1;
474 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
475 assert(I <= this->end() && "Inserting past the end of the vector.");
477 if (this->EndX >= this->CapacityX) {
478 size_t EltNo = I-this->begin();
480 I = this->begin()+EltNo;
483 ::new ((void*) this->end()) T(::std::move(this->back()));
484 // Push everything else over.
485 this->move_backward(I, this->end()-1, this->end());
486 this->setEnd(this->end()+1);
488 // If we just moved the element we're inserting, be sure to update
491 if (I <= EltPtr && EltPtr < this->EndX)
494 *I = ::std::move(*EltPtr);
498 iterator insert(iterator I, const T &Elt) {
499 if (I == this->end()) { // Important special case for empty vector.
500 this->push_back(Elt);
501 return this->end()-1;
504 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
505 assert(I <= this->end() && "Inserting past the end of the vector.");
507 if (this->EndX >= this->CapacityX) {
508 size_t EltNo = I-this->begin();
510 I = this->begin()+EltNo;
512 ::new ((void*) this->end()) T(std::move(this->back()));
513 // Push everything else over.
514 this->move_backward(I, this->end()-1, this->end());
515 this->setEnd(this->end()+1);
517 // If we just moved the element we're inserting, be sure to update
519 const T *EltPtr = &Elt;
520 if (I <= EltPtr && EltPtr < this->EndX)
527 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
528 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
529 size_t InsertElt = I - this->begin();
531 if (I == this->end()) { // Important special case for empty vector.
532 append(NumToInsert, Elt);
533 return this->begin()+InsertElt;
536 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
537 assert(I <= this->end() && "Inserting past the end of the vector.");
539 // Ensure there is enough space.
540 reserve(static_cast<unsigned>(this->size() + NumToInsert));
542 // Uninvalidate the iterator.
543 I = this->begin()+InsertElt;
545 // If there are more elements between the insertion point and the end of the
546 // range than there are being inserted, we can use a simple approach to
547 // insertion. Since we already reserved space, we know that this won't
548 // reallocate the vector.
549 if (size_t(this->end()-I) >= NumToInsert) {
550 T *OldEnd = this->end();
551 append(std::move_iterator<iterator>(this->end() - NumToInsert),
552 std::move_iterator<iterator>(this->end()));
554 // Copy the existing elements that get replaced.
555 this->move_backward(I, OldEnd-NumToInsert, OldEnd);
557 std::fill_n(I, NumToInsert, Elt);
561 // Otherwise, we're inserting more elements than exist already, and we're
562 // not inserting at the end.
564 // Move over the elements that we're about to overwrite.
565 T *OldEnd = this->end();
566 this->setEnd(this->end() + NumToInsert);
567 size_t NumOverwritten = OldEnd-I;
568 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
570 // Replace the overwritten part.
571 std::fill_n(I, NumOverwritten, Elt);
573 // Insert the non-overwritten middle part.
574 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
578 template<typename ItTy>
579 iterator insert(iterator I, ItTy From, ItTy To) {
580 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
581 size_t InsertElt = I - this->begin();
583 if (I == this->end()) { // Important special case for empty vector.
585 return this->begin()+InsertElt;
588 assert(I >= this->begin() && "Insertion iterator is out of bounds.");
589 assert(I <= this->end() && "Inserting past the end of the vector.");
591 size_t NumToInsert = std::distance(From, To);
593 // Ensure there is enough space.
594 reserve(static_cast<unsigned>(this->size() + NumToInsert));
596 // Uninvalidate the iterator.
597 I = this->begin()+InsertElt;
599 // If there are more elements between the insertion point and the end of the
600 // range than there are being inserted, we can use a simple approach to
601 // insertion. Since we already reserved space, we know that this won't
602 // reallocate the vector.
603 if (size_t(this->end()-I) >= NumToInsert) {
604 T *OldEnd = this->end();
605 append(std::move_iterator<iterator>(this->end() - NumToInsert),
606 std::move_iterator<iterator>(this->end()));
608 // Copy the existing elements that get replaced.
609 this->move_backward(I, OldEnd-NumToInsert, OldEnd);
611 std::copy(From, To, I);
615 // Otherwise, we're inserting more elements than exist already, and we're
616 // not inserting at the end.
618 // Move over the elements that we're about to overwrite.
619 T *OldEnd = this->end();
620 this->setEnd(this->end() + NumToInsert);
621 size_t NumOverwritten = OldEnd-I;
622 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
624 // Replace the overwritten part.
625 for (T *J = I; NumOverwritten > 0; --NumOverwritten) {
630 // Insert the non-overwritten middle part.
631 this->uninitialized_copy(From, To, OldEnd);
635 SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
637 SmallVectorImpl &operator=(SmallVectorImpl &&RHS);
639 bool operator==(const SmallVectorImpl &RHS) const {
640 if (this->size() != RHS.size()) return false;
641 return std::equal(this->begin(), this->end(), RHS.begin());
643 bool operator!=(const SmallVectorImpl &RHS) const {
644 return !(*this == RHS);
647 bool operator<(const SmallVectorImpl &RHS) const {
648 return std::lexicographical_compare(this->begin(), this->end(),
649 RHS.begin(), RHS.end());
652 /// Set the array size to \p N, which the current array must have enough
655 /// This does not construct or destroy any elements in the vector.
657 /// Clients can use this in conjunction with capacity() to write past the end
658 /// of the buffer when they know that more elements are available, and only
659 /// update the size later. This avoids the cost of value initializing elements
660 /// which will only be overwritten.
661 void set_size(unsigned N) {
662 assert(N <= this->capacity());
663 this->setEnd(this->begin() + N);
668 template <typename T>
669 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
670 if (this == &RHS) return;
672 // We can only avoid copying elements if neither vector is small.
673 if (!this->isSmall() && !RHS.isSmall()) {
674 std::swap(this->BeginX, RHS.BeginX);
675 std::swap(this->EndX, RHS.EndX);
676 std::swap(this->CapacityX, RHS.CapacityX);
679 if (RHS.size() > this->capacity())
680 this->grow(RHS.size());
681 if (this->size() > RHS.capacity())
682 RHS.grow(this->size());
684 // Swap the shared elements.
685 size_t NumShared = this->size();
686 if (NumShared > RHS.size()) NumShared = RHS.size();
687 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
688 std::swap((*this)[i], RHS[i]);
690 // Copy over the extra elts.
691 if (this->size() > RHS.size()) {
692 size_t EltDiff = this->size() - RHS.size();
693 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
694 RHS.setEnd(RHS.end()+EltDiff);
695 this->destroy_range(this->begin()+NumShared, this->end());
696 this->setEnd(this->begin()+NumShared);
697 } else if (RHS.size() > this->size()) {
698 size_t EltDiff = RHS.size() - this->size();
699 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
700 this->setEnd(this->end() + EltDiff);
701 this->destroy_range(RHS.begin()+NumShared, RHS.end());
702 RHS.setEnd(RHS.begin()+NumShared);
706 template <typename T>
707 SmallVectorImpl<T> &SmallVectorImpl<T>::
708 operator=(const SmallVectorImpl<T> &RHS) {
709 // Avoid self-assignment.
710 if (this == &RHS) return *this;
712 // If we already have sufficient space, assign the common elements, then
713 // destroy any excess.
714 size_t RHSSize = RHS.size();
715 size_t CurSize = this->size();
716 if (CurSize >= RHSSize) {
717 // Assign common elements.
720 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
722 NewEnd = this->begin();
724 // Destroy excess elements.
725 this->destroy_range(NewEnd, this->end());
728 this->setEnd(NewEnd);
732 // If we have to grow to have enough elements, destroy the current elements.
733 // This allows us to avoid copying them during the grow.
734 // FIXME: don't do this if they're efficiently moveable.
735 if (this->capacity() < RHSSize) {
736 // Destroy current elements.
737 this->destroy_range(this->begin(), this->end());
738 this->setEnd(this->begin());
741 } else if (CurSize) {
742 // Otherwise, use assignment for the already-constructed elements.
743 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
746 // Copy construct the new elements in place.
747 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
748 this->begin()+CurSize);
751 this->setEnd(this->begin()+RHSSize);
755 template <typename T>
756 SmallVectorImpl<T> &SmallVectorImpl<T>::operator=(SmallVectorImpl<T> &&RHS) {
757 // Avoid self-assignment.
758 if (this == &RHS) return *this;
760 // If the RHS isn't small, clear this vector and then steal its buffer.
761 if (!RHS.isSmall()) {
762 this->destroy_range(this->begin(), this->end());
763 if (!this->isSmall()) free(this->begin());
764 this->BeginX = RHS.BeginX;
765 this->EndX = RHS.EndX;
766 this->CapacityX = RHS.CapacityX;
771 // If we already have sufficient space, assign the common elements, then
772 // destroy any excess.
773 size_t RHSSize = RHS.size();
774 size_t CurSize = this->size();
775 if (CurSize >= RHSSize) {
776 // Assign common elements.
777 iterator NewEnd = this->begin();
779 NewEnd = this->move(RHS.begin(), RHS.end(), NewEnd);
781 // Destroy excess elements and trim the bounds.
782 this->destroy_range(NewEnd, this->end());
783 this->setEnd(NewEnd);
791 // If we have to grow to have enough elements, destroy the current elements.
792 // This allows us to avoid copying them during the grow.
793 // FIXME: this may not actually make any sense if we can efficiently move
795 if (this->capacity() < RHSSize) {
796 // Destroy current elements.
797 this->destroy_range(this->begin(), this->end());
798 this->setEnd(this->begin());
801 } else if (CurSize) {
802 // Otherwise, use assignment for the already-constructed elements.
803 this->move(RHS.begin(), RHS.begin()+CurSize, this->begin());
806 // Move-construct the new elements in place.
807 this->uninitialized_move(RHS.begin()+CurSize, RHS.end(),
808 this->begin()+CurSize);
811 this->setEnd(this->begin()+RHSSize);
817 /// Storage for the SmallVector elements which aren't contained in
818 /// SmallVectorTemplateCommon. There are 'N-1' elements here. The remaining '1'
819 /// element is in the base class. This is specialized for the N=1 and N=0 cases
820 /// to avoid allocating unnecessary storage.
821 template <typename T, unsigned N>
822 struct SmallVectorStorage {
823 typename SmallVectorTemplateCommon<T>::U InlineElts[N - 1];
825 template <typename T> struct SmallVectorStorage<T, 1> {};
826 template <typename T> struct SmallVectorStorage<T, 0> {};
828 /// This is a 'vector' (really, a variable-sized array), optimized
829 /// for the case when the array is small. It contains some number of elements
830 /// in-place, which allows it to avoid heap allocation when the actual number of
831 /// elements is below that threshold. This allows normal "small" cases to be
832 /// fast without losing generality for large inputs.
834 /// Note that this does not attempt to be exception safe.
836 template <typename T, unsigned N>
837 class SmallVector : public SmallVectorImpl<T> {
838 /// Inline space for elements which aren't stored in the base class.
839 SmallVectorStorage<T, N> Storage;
841 SmallVector() : SmallVectorImpl<T>(N) {
844 explicit SmallVector(unsigned Size, const T &Value = T())
845 : SmallVectorImpl<T>(N) {
846 this->assign(Size, Value);
849 template<typename ItTy>
850 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
854 template <typename RangeTy>
855 explicit SmallVector(const llvm::iterator_range<RangeTy> R)
856 : SmallVectorImpl<T>(N) {
857 this->append(R.begin(), R.end());
860 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(N) {
862 SmallVectorImpl<T>::operator=(RHS);
865 const SmallVector &operator=(const SmallVector &RHS) {
866 SmallVectorImpl<T>::operator=(RHS);
870 SmallVector(SmallVector &&RHS) : SmallVectorImpl<T>(N) {
872 SmallVectorImpl<T>::operator=(::std::move(RHS));
875 const SmallVector &operator=(SmallVector &&RHS) {
876 SmallVectorImpl<T>::operator=(::std::move(RHS));
881 template<typename T, unsigned N>
882 static inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
883 return X.capacity_in_bytes();
886 } // End llvm namespace
889 /// Implement std::swap in terms of SmallVector swap.
892 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
896 /// Implement std::swap in terms of SmallVector swap.
897 template<typename T, unsigned N>
899 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {