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"
27 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
28 // additional overloads so that elements with pointer types are recognized as
29 // scalars and not objects, causing bizarre type conversion errors.
30 template<class T1, class T2>
31 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
32 _Scalar_ptr_iterator_tag _Cat;
36 template<class T1, class T2>
37 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
38 _Scalar_ptr_iterator_tag _Cat;
42 // FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
43 // is that the above hack won't work if it wasn't fixed.
50 /// SmallVectorBase - This is all the non-templated stuff common to all
52 class SmallVectorBase {
54 void *BeginX, *EndX, *CapacityX;
56 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
57 // don't want it to be automatically run, so we need to represent the space as
58 // something else. An array of char would work great, but might not be
59 // aligned sufficiently. Instead, we either use GCC extensions, or some
60 // number of union instances for the space, which guarantee maximal alignment.
63 char X __attribute__((aligned(8)));
73 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
76 SmallVectorBase(size_t Size)
77 : BeginX(&FirstEl), EndX(&FirstEl), CapacityX((char*)&FirstEl+Size) {}
79 /// isSmall - Return true if this is a smallvector which has not had dynamic
80 /// memory allocated for it.
81 bool isSmall() const {
82 return BeginX == static_cast<const void*>(&FirstEl);
85 /// size_in_bytes - This returns size()*sizeof(T).
86 size_t size_in_bytes() const {
87 return size_t((char*)EndX - (char*)BeginX);
90 /// capacity_in_bytes - This returns capacity()*sizeof(T).
91 size_t capacity_in_bytes() const {
92 return size_t((char*)CapacityX - (char*)BeginX);
95 /// grow_pod - This is an implementation of the grow() method which only works
96 /// on POD-like datatypes and is out of line to reduce code duplication.
97 void grow_pod(size_t MinSizeInBytes, size_t TSize);
100 bool empty() const { return BeginX == EndX; }
104 template <typename T>
105 class SmallVectorTemplateCommon : public SmallVectorBase {
107 void setEnd(T *P) { this->EndX = P; }
109 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(Size) {}
111 typedef size_t size_type;
112 typedef ptrdiff_t difference_type;
113 typedef T value_type;
115 typedef const T *const_iterator;
117 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
118 typedef std::reverse_iterator<iterator> reverse_iterator;
120 typedef T &reference;
121 typedef const T &const_reference;
123 typedef const T *const_pointer;
125 // forward iterator creation methods.
126 iterator begin() { return (iterator)this->BeginX; }
127 const_iterator begin() const { return (const_iterator)this->BeginX; }
128 iterator end() { return (iterator)this->EndX; }
129 const_iterator end() const { return (const_iterator)this->EndX; }
131 iterator capacity_ptr() { return (iterator)this->CapacityX; }
132 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
135 // reverse iterator creation methods.
136 reverse_iterator rbegin() { return reverse_iterator(end()); }
137 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
138 reverse_iterator rend() { return reverse_iterator(begin()); }
139 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
141 size_type size() const { return end()-begin(); }
142 size_type max_size() const { return size_type(-1) / sizeof(T); }
144 /// capacity - Return the total number of elements in the currently allocated
146 size_t capacity() const { return capacity_ptr() - begin(); }
148 /// data - Return a pointer to the vector's buffer, even if empty().
149 pointer data() { return pointer(begin()); }
150 /// data - Return a pointer to the vector's buffer, even if empty().
151 const_pointer data() const { return const_pointer(begin()); }
153 reference operator[](unsigned idx) {
154 assert(begin() + idx < end());
157 const_reference operator[](unsigned idx) const {
158 assert(begin() + idx < end());
165 const_reference front() const {
172 const_reference back() const {
177 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
178 /// implementations that are designed to work with non-POD-like T's.
179 template <typename T, bool isPodLike>
180 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
182 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
184 static void destroy_range(T *S, T *E) {
191 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
192 /// starting with "Dest", constructing elements into it as needed.
193 template<typename It1, typename It2>
194 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
195 std::uninitialized_copy(I, E, Dest);
198 /// grow - double the size of the allocated memory, guaranteeing space for at
199 /// least one more element or MinSize if specified.
200 void grow(size_t MinSize = 0);
203 // Define this out-of-line to dissuade the C++ compiler from inlining it.
204 template <typename T, bool isPodLike>
205 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
206 size_t CurCapacity = this->capacity();
207 size_t CurSize = this->size();
208 size_t NewCapacity = 2*CurCapacity;
209 if (NewCapacity < MinSize)
210 NewCapacity = MinSize;
211 T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));
213 // Copy the elements over.
214 this->uninitialized_copy(this->begin(), this->end(), NewElts);
216 // Destroy the original elements.
217 destroy_range(this->begin(), this->end());
219 // If this wasn't grown from the inline copy, deallocate the old space.
220 if (!this->isSmall())
223 this->setEnd(NewElts+CurSize);
224 this->BeginX = NewElts;
225 this->CapacityX = this->begin()+NewCapacity;
229 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
230 /// implementations that are designed to work with POD-like T's.
231 template <typename T>
232 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
234 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
236 // No need to do a destroy loop for POD's.
237 static void destroy_range(T *, T *) {}
239 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
240 /// starting with "Dest", constructing elements into it as needed.
241 template<typename It1, typename It2>
242 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
243 // Arbitrary iterator types; just use the basic implementation.
244 std::uninitialized_copy(I, E, Dest);
247 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
248 /// starting with "Dest", constructing elements into it as needed.
249 template<typename T1, typename T2>
250 static void uninitialized_copy(T1 *I, T1 *E, T2 *Dest) {
251 // Use memcpy for PODs iterated by pointers (which includes SmallVector
252 // iterators): std::uninitialized_copy optimizes to memmove, but we can
254 memcpy(Dest, I, (E-I)*sizeof(T));
257 /// grow - double the size of the allocated memory, guaranteeing space for at
258 /// least one more element or MinSize if specified.
259 void grow(size_t MinSize = 0) {
260 this->grow_pod(MinSize*sizeof(T), sizeof(T));
265 /// SmallVectorImpl - This class consists of common code factored out of the
266 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
267 /// template parameter.
268 template <typename T>
269 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
270 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
272 typedef typename SuperClass::iterator iterator;
273 typedef typename SuperClass::size_type size_type;
275 // Default ctor - Initialize to empty.
276 explicit SmallVectorImpl(unsigned N)
277 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
281 // Destroy the constructed elements in the vector.
282 this->destroy_range(this->begin(), this->end());
284 // If this wasn't grown from the inline copy, deallocate the old space.
285 if (!this->isSmall())
291 this->destroy_range(this->begin(), this->end());
292 this->EndX = this->BeginX;
295 void resize(unsigned N) {
296 if (N < this->size()) {
297 this->destroy_range(this->begin()+N, this->end());
298 this->setEnd(this->begin()+N);
299 } else if (N > this->size()) {
300 if (this->capacity() < N)
302 this->construct_range(this->end(), this->begin()+N, T());
303 this->setEnd(this->begin()+N);
307 void resize(unsigned N, const T &NV) {
308 if (N < this->size()) {
309 this->destroy_range(this->begin()+N, this->end());
310 this->setEnd(this->begin()+N);
311 } else if (N > this->size()) {
312 if (this->capacity() < N)
314 construct_range(this->end(), this->begin()+N, NV);
315 this->setEnd(this->begin()+N);
319 void reserve(unsigned N) {
320 if (this->capacity() < N)
324 void push_back(const T &Elt) {
325 if (this->EndX < this->CapacityX) {
327 new (this->end()) T(Elt);
328 this->setEnd(this->end()+1);
336 this->setEnd(this->end()-1);
341 T Result = this->back();
347 void swap(SmallVectorImpl &RHS);
349 /// append - Add the specified range to the end of the SmallVector.
351 template<typename in_iter>
352 void append(in_iter in_start, in_iter in_end) {
353 size_type NumInputs = std::distance(in_start, in_end);
354 // Grow allocated space if needed.
355 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
356 this->grow(this->size()+NumInputs);
358 // Copy the new elements over.
359 // TODO: NEED To compile time dispatch on whether in_iter is a random access
360 // iterator to use the fast uninitialized_copy.
361 std::uninitialized_copy(in_start, in_end, this->end());
362 this->setEnd(this->end() + NumInputs);
365 /// append - Add the specified range to the end of the SmallVector.
367 void append(size_type NumInputs, const T &Elt) {
368 // Grow allocated space if needed.
369 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
370 this->grow(this->size()+NumInputs);
372 // Copy the new elements over.
373 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
374 this->setEnd(this->end() + NumInputs);
377 void assign(unsigned NumElts, const T &Elt) {
379 if (this->capacity() < NumElts)
381 this->setEnd(this->begin()+NumElts);
382 construct_range(this->begin(), this->end(), Elt);
385 iterator erase(iterator I) {
387 // Shift all elts down one.
388 std::copy(I+1, this->end(), I);
389 // Drop the last elt.
394 iterator erase(iterator S, iterator E) {
396 // Shift all elts down.
397 iterator I = std::copy(E, this->end(), S);
398 // Drop the last elts.
399 this->destroy_range(I, this->end());
404 iterator insert(iterator I, const T &Elt) {
405 if (I == this->end()) { // Important special case for empty vector.
407 return this->end()-1;
410 if (this->EndX < this->CapacityX) {
412 new (this->end()) T(this->back());
413 this->setEnd(this->end()+1);
414 // Push everything else over.
415 std::copy_backward(I, this->end()-1, this->end());
419 size_t EltNo = I-this->begin();
421 I = this->begin()+EltNo;
425 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
426 if (I == this->end()) { // Important special case for empty vector.
427 append(NumToInsert, Elt);
428 return this->end()-1;
431 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
432 size_t InsertElt = I - this->begin();
434 // Ensure there is enough space.
435 reserve(static_cast<unsigned>(this->size() + NumToInsert));
437 // Uninvalidate the iterator.
438 I = this->begin()+InsertElt;
440 // If there are more elements between the insertion point and the end of the
441 // range than there are being inserted, we can use a simple approach to
442 // insertion. Since we already reserved space, we know that this won't
443 // reallocate the vector.
444 if (size_t(this->end()-I) >= NumToInsert) {
445 T *OldEnd = this->end();
446 append(this->end()-NumToInsert, this->end());
448 // Copy the existing elements that get replaced.
449 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
451 std::fill_n(I, NumToInsert, Elt);
455 // Otherwise, we're inserting more elements than exist already, and we're
456 // not inserting at the end.
458 // Copy over the elements that we're about to overwrite.
459 T *OldEnd = this->end();
460 this->setEnd(this->end() + NumToInsert);
461 size_t NumOverwritten = OldEnd-I;
462 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
464 // Replace the overwritten part.
465 std::fill_n(I, NumOverwritten, Elt);
467 // Insert the non-overwritten middle part.
468 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
472 template<typename ItTy>
473 iterator insert(iterator I, ItTy From, ItTy To) {
474 if (I == this->end()) { // Important special case for empty vector.
476 return this->end()-1;
479 size_t NumToInsert = std::distance(From, To);
480 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
481 size_t InsertElt = I - this->begin();
483 // Ensure there is enough space.
484 reserve(static_cast<unsigned>(this->size() + NumToInsert));
486 // Uninvalidate the iterator.
487 I = this->begin()+InsertElt;
489 // If there are more elements between the insertion point and the end of the
490 // range than there are being inserted, we can use a simple approach to
491 // insertion. Since we already reserved space, we know that this won't
492 // reallocate the vector.
493 if (size_t(this->end()-I) >= NumToInsert) {
494 T *OldEnd = this->end();
495 append(this->end()-NumToInsert, this->end());
497 // Copy the existing elements that get replaced.
498 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
500 std::copy(From, To, I);
504 // Otherwise, we're inserting more elements than exist already, and we're
505 // not inserting at the end.
507 // Copy over the elements that we're about to overwrite.
508 T *OldEnd = this->end();
509 this->setEnd(this->end() + NumToInsert);
510 size_t NumOverwritten = OldEnd-I;
511 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
513 // Replace the overwritten part.
514 for (; NumOverwritten > 0; --NumOverwritten) {
519 // Insert the non-overwritten middle part.
520 this->uninitialized_copy(From, To, OldEnd);
524 const SmallVectorImpl
525 &operator=(const SmallVectorImpl &RHS);
527 bool operator==(const SmallVectorImpl &RHS) const {
528 if (this->size() != RHS.size()) return false;
529 return std::equal(this->begin(), this->end(), RHS.begin());
531 bool operator!=(const SmallVectorImpl &RHS) const {
532 return !(*this == RHS);
535 bool operator<(const SmallVectorImpl &RHS) const {
536 return std::lexicographical_compare(this->begin(), this->end(),
537 RHS.begin(), RHS.end());
540 /// set_size - Set the array size to \arg N, which the current array must have
541 /// enough capacity for.
543 /// This does not construct or destroy any elements in the vector.
545 /// Clients can use this in conjunction with capacity() to write past the end
546 /// of the buffer when they know that more elements are available, and only
547 /// update the size later. This avoids the cost of value initializing elements
548 /// which will only be overwritten.
549 void set_size(unsigned N) {
550 assert(N <= this->capacity());
551 this->setEnd(this->begin() + N);
555 static void construct_range(T *S, T *E, const T &Elt) {
562 template <typename T>
563 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
564 if (this == &RHS) return;
566 // We can only avoid copying elements if neither vector is small.
567 if (!this->isSmall() && !RHS.isSmall()) {
568 std::swap(this->BeginX, RHS.BeginX);
569 std::swap(this->EndX, RHS.EndX);
570 std::swap(this->CapacityX, RHS.CapacityX);
573 if (RHS.size() > this->capacity())
574 this->grow(RHS.size());
575 if (this->size() > RHS.capacity())
576 RHS.grow(this->size());
578 // Swap the shared elements.
579 size_t NumShared = this->size();
580 if (NumShared > RHS.size()) NumShared = RHS.size();
581 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
582 std::swap((*this)[i], RHS[i]);
584 // Copy over the extra elts.
585 if (this->size() > RHS.size()) {
586 size_t EltDiff = this->size() - RHS.size();
587 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
588 RHS.setEnd(RHS.end()+EltDiff);
589 this->destroy_range(this->begin()+NumShared, this->end());
590 this->setEnd(this->begin()+NumShared);
591 } else if (RHS.size() > this->size()) {
592 size_t EltDiff = RHS.size() - this->size();
593 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
594 this->setEnd(this->end() + EltDiff);
595 this->destroy_range(RHS.begin()+NumShared, RHS.end());
596 RHS.setEnd(RHS.begin()+NumShared);
600 template <typename T>
601 const SmallVectorImpl<T> &SmallVectorImpl<T>::
602 operator=(const SmallVectorImpl<T> &RHS) {
603 // Avoid self-assignment.
604 if (this == &RHS) return *this;
606 // If we already have sufficient space, assign the common elements, then
607 // destroy any excess.
608 size_t RHSSize = RHS.size();
609 size_t CurSize = this->size();
610 if (CurSize >= RHSSize) {
611 // Assign common elements.
614 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
616 NewEnd = this->begin();
618 // Destroy excess elements.
619 this->destroy_range(NewEnd, this->end());
622 this->setEnd(NewEnd);
626 // If we have to grow to have enough elements, destroy the current elements.
627 // This allows us to avoid copying them during the grow.
628 if (this->capacity() < RHSSize) {
629 // Destroy current elements.
630 this->destroy_range(this->begin(), this->end());
631 this->setEnd(this->begin());
634 } else if (CurSize) {
635 // Otherwise, use assignment for the already-constructed elements.
636 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
639 // Copy construct the new elements in place.
640 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
641 this->begin()+CurSize);
644 this->setEnd(this->begin()+RHSSize);
649 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
650 /// for the case when the array is small. It contains some number of elements
651 /// in-place, which allows it to avoid heap allocation when the actual number of
652 /// elements is below that threshold. This allows normal "small" cases to be
653 /// fast without losing generality for large inputs.
655 /// Note that this does not attempt to be exception safe.
657 template <typename T, unsigned N>
658 class SmallVector : public SmallVectorImpl<T> {
659 /// InlineElts - These are 'N-1' elements that are stored inline in the body
660 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
661 typedef typename SmallVectorImpl<T>::U U;
663 // MinUs - The number of U's require to cover N T's.
664 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
665 static_cast<unsigned int>(sizeof(U)) - 1) /
666 static_cast<unsigned int>(sizeof(U)),
668 // NumInlineEltsElts - The number of elements actually in this array. There
669 // is already one in the parent class, and we have to round up to avoid
670 // having a zero-element array.
671 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
673 // NumTsAvailable - The number of T's we actually have space for, which may
674 // be more than N due to rounding.
675 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
676 static_cast<unsigned int>(sizeof(T))
678 U InlineElts[NumInlineEltsElts];
680 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
683 explicit SmallVector(unsigned Size, const T &Value = T())
684 : SmallVectorImpl<T>(NumTsAvailable) {
687 this->push_back(Value);
690 template<typename ItTy>
691 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
695 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
697 SmallVectorImpl<T>::operator=(RHS);
700 const SmallVector &operator=(const SmallVector &RHS) {
701 SmallVectorImpl<T>::operator=(RHS);
707 } // End llvm namespace
710 /// Implement std::swap in terms of SmallVector swap.
713 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
717 /// Implement std::swap in terms of SmallVector swap.
718 template<typename T, unsigned N>
720 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {