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/type_traits.h"
29 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
30 // additional overloads so that elements with pointer types are recognized as
31 // scalars and not objects, causing bizarre type conversion errors.
32 template<class T1, class T2>
33 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
34 _Scalar_ptr_iterator_tag _Cat;
38 template<class T1, class T2>
39 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
40 _Scalar_ptr_iterator_tag _Cat;
44 // FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
45 // is that the above hack won't work if it wasn't fixed.
52 /// SmallVectorBase - This is all the non-templated stuff common to all
54 class SmallVectorBase {
56 void *BeginX, *EndX, *CapacityX;
58 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
59 // don't want it to be automatically run, so we need to represent the space as
60 // something else. An array of char would work great, but might not be
61 // aligned sufficiently. Instead we use some number of union instances for
62 // the space, which guarantee maximal alignment.
69 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
72 SmallVectorBase(size_t Size)
73 : BeginX(&FirstEl), EndX(&FirstEl), CapacityX((char*)&FirstEl+Size) {}
75 /// isSmall - Return true if this is a smallvector which has not had dynamic
76 /// memory allocated for it.
77 bool isSmall() const {
78 return BeginX == static_cast<const void*>(&FirstEl);
81 /// grow_pod - This is an implementation of the grow() method which only works
82 /// on POD-like data types and is out of line to reduce code duplication.
83 void grow_pod(size_t MinSizeInBytes, size_t TSize);
86 /// size_in_bytes - This returns size()*sizeof(T).
87 size_t size_in_bytes() const {
88 return size_t((char*)EndX - (char*)BeginX);
91 /// capacity_in_bytes - This returns capacity()*sizeof(T).
92 size_t capacity_in_bytes() const {
93 return size_t((char*)CapacityX - (char*)BeginX);
96 bool empty() const { return BeginX == EndX; }
100 template <typename T>
101 class SmallVectorTemplateCommon : public SmallVectorBase {
103 void setEnd(T *P) { this->EndX = P; }
105 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(Size) {}
107 typedef size_t size_type;
108 typedef ptrdiff_t difference_type;
109 typedef T value_type;
111 typedef const T *const_iterator;
113 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
114 typedef std::reverse_iterator<iterator> reverse_iterator;
116 typedef T &reference;
117 typedef const T &const_reference;
119 typedef const T *const_pointer;
121 // forward iterator creation methods.
122 iterator begin() { return (iterator)this->BeginX; }
123 const_iterator begin() const { return (const_iterator)this->BeginX; }
124 iterator end() { return (iterator)this->EndX; }
125 const_iterator end() const { return (const_iterator)this->EndX; }
127 iterator capacity_ptr() { return (iterator)this->CapacityX; }
128 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
131 // reverse iterator creation methods.
132 reverse_iterator rbegin() { return reverse_iterator(end()); }
133 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
134 reverse_iterator rend() { return reverse_iterator(begin()); }
135 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
137 size_type size() const { return end()-begin(); }
138 size_type max_size() const { return size_type(-1) / sizeof(T); }
140 /// capacity - Return the total number of elements in the currently allocated
142 size_t capacity() const { return capacity_ptr() - begin(); }
144 /// data - Return a pointer to the vector's buffer, even if empty().
145 pointer data() { return pointer(begin()); }
146 /// data - Return a pointer to the vector's buffer, even if empty().
147 const_pointer data() const { return const_pointer(begin()); }
149 reference operator[](unsigned idx) {
150 assert(begin() + idx < end());
153 const_reference operator[](unsigned idx) const {
154 assert(begin() + idx < end());
161 const_reference front() const {
168 const_reference back() const {
173 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
174 /// implementations that are designed to work with non-POD-like T's.
175 template <typename T, bool isPodLike>
176 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
178 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
180 static void destroy_range(T *S, T *E) {
187 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
188 /// starting with "Dest", constructing elements into it as needed.
189 template<typename It1, typename It2>
190 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
191 std::uninitialized_copy(I, E, Dest);
194 /// grow - double the size of the allocated memory, guaranteeing space for at
195 /// least one more element or MinSize if specified.
196 void grow(size_t MinSize = 0);
199 // Define this out-of-line to dissuade the C++ compiler from inlining it.
200 template <typename T, bool isPodLike>
201 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
202 size_t CurCapacity = this->capacity();
203 size_t CurSize = this->size();
204 size_t NewCapacity = 2*CurCapacity + 1; // Always grow, even from zero.
205 if (NewCapacity < MinSize)
206 NewCapacity = MinSize;
207 T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));
209 // Copy the elements over.
210 this->uninitialized_copy(this->begin(), this->end(), NewElts);
212 // Destroy the original elements.
213 destroy_range(this->begin(), this->end());
215 // If this wasn't grown from the inline copy, deallocate the old space.
216 if (!this->isSmall())
219 this->setEnd(NewElts+CurSize);
220 this->BeginX = NewElts;
221 this->CapacityX = this->begin()+NewCapacity;
225 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
226 /// implementations that are designed to work with POD-like T's.
227 template <typename T>
228 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
230 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
232 // No need to do a destroy loop for POD's.
233 static void destroy_range(T *, T *) {}
235 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
236 /// starting with "Dest", constructing elements into it as needed.
237 template<typename It1, typename It2>
238 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
239 // Arbitrary iterator types; just use the basic implementation.
240 std::uninitialized_copy(I, E, Dest);
243 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
244 /// starting with "Dest", constructing elements into it as needed.
245 template<typename T1, typename T2>
246 static void uninitialized_copy(T1 *I, T1 *E, T2 *Dest) {
247 // Use memcpy for PODs iterated by pointers (which includes SmallVector
248 // iterators): std::uninitialized_copy optimizes to memmove, but we can
250 memcpy(Dest, I, (E-I)*sizeof(T));
253 /// grow - double the size of the allocated memory, guaranteeing space for at
254 /// least one more element or MinSize if specified.
255 void grow(size_t MinSize = 0) {
256 this->grow_pod(MinSize*sizeof(T), sizeof(T));
261 /// SmallVectorImpl - This class consists of common code factored out of the
262 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
263 /// template parameter.
264 template <typename T>
265 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
266 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
268 SmallVectorImpl(const SmallVectorImpl&); // DISABLED.
270 typedef typename SuperClass::iterator iterator;
271 typedef typename SuperClass::size_type size_type;
273 // Default ctor - Initialize to empty.
274 explicit SmallVectorImpl(unsigned N)
275 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
279 // Destroy the constructed elements in the vector.
280 this->destroy_range(this->begin(), this->end());
282 // If this wasn't grown from the inline copy, deallocate the old space.
283 if (!this->isSmall())
289 this->destroy_range(this->begin(), this->end());
290 this->EndX = this->BeginX;
293 void resize(unsigned N) {
294 if (N < this->size()) {
295 this->destroy_range(this->begin()+N, this->end());
296 this->setEnd(this->begin()+N);
297 } else if (N > this->size()) {
298 if (this->capacity() < N)
300 this->construct_range(this->end(), this->begin()+N, T());
301 this->setEnd(this->begin()+N);
305 void resize(unsigned N, const T &NV) {
306 if (N < this->size()) {
307 this->destroy_range(this->begin()+N, this->end());
308 this->setEnd(this->begin()+N);
309 } else if (N > this->size()) {
310 if (this->capacity() < N)
312 construct_range(this->end(), this->begin()+N, NV);
313 this->setEnd(this->begin()+N);
317 void reserve(unsigned N) {
318 if (this->capacity() < N)
322 void push_back(const T &Elt) {
323 if (this->EndX < this->CapacityX) {
325 new (this->end()) T(Elt);
326 this->setEnd(this->end()+1);
334 this->setEnd(this->end()-1);
339 T Result = this->back();
344 void swap(SmallVectorImpl &RHS);
346 /// append - Add the specified range to the end of the SmallVector.
348 template<typename in_iter>
349 void append(in_iter in_start, in_iter in_end) {
350 size_type NumInputs = std::distance(in_start, in_end);
351 // Grow allocated space if needed.
352 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
353 this->grow(this->size()+NumInputs);
355 // Copy the new elements over.
356 // TODO: NEED To compile time dispatch on whether in_iter is a random access
357 // iterator to use the fast uninitialized_copy.
358 std::uninitialized_copy(in_start, in_end, this->end());
359 this->setEnd(this->end() + NumInputs);
362 /// append - Add the specified range to the end of the SmallVector.
364 void append(size_type NumInputs, const T &Elt) {
365 // Grow allocated space if needed.
366 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
367 this->grow(this->size()+NumInputs);
369 // Copy the new elements over.
370 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
371 this->setEnd(this->end() + NumInputs);
374 void assign(unsigned NumElts, const T &Elt) {
376 if (this->capacity() < NumElts)
378 this->setEnd(this->begin()+NumElts);
379 construct_range(this->begin(), this->end(), Elt);
382 iterator erase(iterator I) {
384 // Shift all elts down one.
385 std::copy(I+1, this->end(), I);
386 // Drop the last elt.
391 iterator erase(iterator S, iterator E) {
393 // Shift all elts down.
394 iterator I = std::copy(E, this->end(), S);
395 // Drop the last elts.
396 this->destroy_range(I, this->end());
401 iterator insert(iterator I, const T &Elt) {
402 if (I == this->end()) { // Important special case for empty vector.
404 return this->end()-1;
407 if (this->EndX < this->CapacityX) {
409 new (this->end()) T(this->back());
410 this->setEnd(this->end()+1);
411 // Push everything else over.
412 std::copy_backward(I, this->end()-1, this->end());
414 // If we just moved the element we're inserting, be sure to update
416 const T *EltPtr = &Elt;
417 if (I <= EltPtr && EltPtr < this->EndX)
423 size_t EltNo = I-this->begin();
425 I = this->begin()+EltNo;
429 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
430 if (I == this->end()) { // Important special case for empty vector.
431 append(NumToInsert, Elt);
432 return this->end()-1;
435 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
436 size_t InsertElt = I - this->begin();
438 // Ensure there is enough space.
439 reserve(static_cast<unsigned>(this->size() + NumToInsert));
441 // Uninvalidate the iterator.
442 I = this->begin()+InsertElt;
444 // If there are more elements between the insertion point and the end of the
445 // range than there are being inserted, we can use a simple approach to
446 // insertion. Since we already reserved space, we know that this won't
447 // reallocate the vector.
448 if (size_t(this->end()-I) >= NumToInsert) {
449 T *OldEnd = this->end();
450 append(this->end()-NumToInsert, this->end());
452 // Copy the existing elements that get replaced.
453 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
455 std::fill_n(I, NumToInsert, Elt);
459 // Otherwise, we're inserting more elements than exist already, and we're
460 // not inserting at the end.
462 // Copy over the elements that we're about to overwrite.
463 T *OldEnd = this->end();
464 this->setEnd(this->end() + NumToInsert);
465 size_t NumOverwritten = OldEnd-I;
466 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
468 // Replace the overwritten part.
469 std::fill_n(I, NumOverwritten, Elt);
471 // Insert the non-overwritten middle part.
472 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
476 template<typename ItTy>
477 iterator insert(iterator I, ItTy From, ItTy To) {
478 if (I == this->end()) { // Important special case for empty vector.
480 return this->end()-1;
483 size_t NumToInsert = std::distance(From, To);
484 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
485 size_t InsertElt = I - this->begin();
487 // Ensure there is enough space.
488 reserve(static_cast<unsigned>(this->size() + NumToInsert));
490 // Uninvalidate the iterator.
491 I = this->begin()+InsertElt;
493 // If there are more elements between the insertion point and the end of the
494 // range than there are being inserted, we can use a simple approach to
495 // insertion. Since we already reserved space, we know that this won't
496 // reallocate the vector.
497 if (size_t(this->end()-I) >= NumToInsert) {
498 T *OldEnd = this->end();
499 append(this->end()-NumToInsert, this->end());
501 // Copy the existing elements that get replaced.
502 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
504 std::copy(From, To, I);
508 // Otherwise, we're inserting more elements than exist already, and we're
509 // not inserting at the end.
511 // Copy over the elements that we're about to overwrite.
512 T *OldEnd = this->end();
513 this->setEnd(this->end() + NumToInsert);
514 size_t NumOverwritten = OldEnd-I;
515 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
517 // Replace the overwritten part.
518 for (; NumOverwritten > 0; --NumOverwritten) {
523 // Insert the non-overwritten middle part.
524 this->uninitialized_copy(From, To, OldEnd);
528 const SmallVectorImpl
529 &operator=(const SmallVectorImpl &RHS);
531 bool operator==(const SmallVectorImpl &RHS) const {
532 if (this->size() != RHS.size()) return false;
533 return std::equal(this->begin(), this->end(), RHS.begin());
535 bool operator!=(const SmallVectorImpl &RHS) const {
536 return !(*this == RHS);
539 bool operator<(const SmallVectorImpl &RHS) const {
540 return std::lexicographical_compare(this->begin(), this->end(),
541 RHS.begin(), RHS.end());
544 /// set_size - Set the array size to \arg N, which the current array must have
545 /// enough capacity for.
547 /// This does not construct or destroy any elements in the vector.
549 /// Clients can use this in conjunction with capacity() to write past the end
550 /// of the buffer when they know that more elements are available, and only
551 /// update the size later. This avoids the cost of value initializing elements
552 /// which will only be overwritten.
553 void set_size(unsigned N) {
554 assert(N <= this->capacity());
555 this->setEnd(this->begin() + N);
559 static void construct_range(T *S, T *E, const T &Elt) {
566 template <typename T>
567 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
568 if (this == &RHS) return;
570 // We can only avoid copying elements if neither vector is small.
571 if (!this->isSmall() && !RHS.isSmall()) {
572 std::swap(this->BeginX, RHS.BeginX);
573 std::swap(this->EndX, RHS.EndX);
574 std::swap(this->CapacityX, RHS.CapacityX);
577 if (RHS.size() > this->capacity())
578 this->grow(RHS.size());
579 if (this->size() > RHS.capacity())
580 RHS.grow(this->size());
582 // Swap the shared elements.
583 size_t NumShared = this->size();
584 if (NumShared > RHS.size()) NumShared = RHS.size();
585 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
586 std::swap((*this)[i], RHS[i]);
588 // Copy over the extra elts.
589 if (this->size() > RHS.size()) {
590 size_t EltDiff = this->size() - RHS.size();
591 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
592 RHS.setEnd(RHS.end()+EltDiff);
593 this->destroy_range(this->begin()+NumShared, this->end());
594 this->setEnd(this->begin()+NumShared);
595 } else if (RHS.size() > this->size()) {
596 size_t EltDiff = RHS.size() - this->size();
597 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
598 this->setEnd(this->end() + EltDiff);
599 this->destroy_range(RHS.begin()+NumShared, RHS.end());
600 RHS.setEnd(RHS.begin()+NumShared);
604 template <typename T>
605 const SmallVectorImpl<T> &SmallVectorImpl<T>::
606 operator=(const SmallVectorImpl<T> &RHS) {
607 // Avoid self-assignment.
608 if (this == &RHS) return *this;
610 // If we already have sufficient space, assign the common elements, then
611 // destroy any excess.
612 size_t RHSSize = RHS.size();
613 size_t CurSize = this->size();
614 if (CurSize >= RHSSize) {
615 // Assign common elements.
618 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
620 NewEnd = this->begin();
622 // Destroy excess elements.
623 this->destroy_range(NewEnd, this->end());
626 this->setEnd(NewEnd);
630 // If we have to grow to have enough elements, destroy the current elements.
631 // This allows us to avoid copying them during the grow.
632 if (this->capacity() < RHSSize) {
633 // Destroy current elements.
634 this->destroy_range(this->begin(), this->end());
635 this->setEnd(this->begin());
638 } else if (CurSize) {
639 // Otherwise, use assignment for the already-constructed elements.
640 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
643 // Copy construct the new elements in place.
644 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
645 this->begin()+CurSize);
648 this->setEnd(this->begin()+RHSSize);
653 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
654 /// for the case when the array is small. It contains some number of elements
655 /// in-place, which allows it to avoid heap allocation when the actual number of
656 /// elements is below that threshold. This allows normal "small" cases to be
657 /// fast without losing generality for large inputs.
659 /// Note that this does not attempt to be exception safe.
661 template <typename T, unsigned N>
662 class SmallVector : public SmallVectorImpl<T> {
663 /// InlineElts - These are 'N-1' elements that are stored inline in the body
664 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
665 typedef typename SmallVectorImpl<T>::U U;
667 // MinUs - The number of U's require to cover N T's.
668 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
669 static_cast<unsigned int>(sizeof(U)) - 1) /
670 static_cast<unsigned int>(sizeof(U)),
672 // NumInlineEltsElts - The number of elements actually in this array. There
673 // is already one in the parent class, and we have to round up to avoid
674 // having a zero-element array.
675 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
677 // NumTsAvailable - The number of T's we actually have space for, which may
678 // be more than N due to rounding.
679 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
680 static_cast<unsigned int>(sizeof(T))
682 U InlineElts[NumInlineEltsElts];
684 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
687 explicit SmallVector(unsigned Size, const T &Value = T())
688 : SmallVectorImpl<T>(NumTsAvailable) {
691 this->push_back(Value);
694 template<typename ItTy>
695 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
699 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
701 SmallVectorImpl<T>::operator=(RHS);
704 const SmallVector &operator=(const SmallVector &RHS) {
705 SmallVectorImpl<T>::operator=(RHS);
711 /// Specialize SmallVector at N=0. This specialization guarantees
712 /// that it can be instantiated at an incomplete T if none of its
713 /// members are required.
714 template <typename T>
715 class SmallVector<T,0> : public SmallVectorImpl<T> {
717 SmallVector() : SmallVectorImpl<T>(0) {}
719 explicit SmallVector(unsigned Size, const T &Value = T())
720 : SmallVectorImpl<T>(0) {
723 this->push_back(Value);
726 template<typename ItTy>
727 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(0) {
731 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(0) {
732 SmallVectorImpl<T>::operator=(RHS);
735 SmallVector &operator=(const SmallVectorImpl<T> &RHS) {
736 return SmallVectorImpl<T>::operator=(RHS);
741 template<typename T, unsigned N>
742 static inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
743 return X.capacity_in_bytes();
746 } // End llvm namespace
749 /// Implement std::swap in terms of SmallVector swap.
752 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
756 /// Implement std::swap in terms of SmallVector swap.
757 template<typename T, unsigned N>
759 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {