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"
28 /// SmallVectorBase - This is all the non-templated stuff common to all
30 class SmallVectorBase {
32 void *BeginX, *EndX, *CapacityX;
34 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
35 // don't want it to be automatically run, so we need to represent the space as
36 // something else. An array of char would work great, but might not be
37 // aligned sufficiently. Instead we use some number of union instances for
38 // the space, which guarantee maximal alignment.
45 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
48 SmallVectorBase(size_t Size)
49 : BeginX(&FirstEl), EndX(&FirstEl), CapacityX((char*)&FirstEl+Size) {}
51 /// isSmall - Return true if this is a smallvector which has not had dynamic
52 /// memory allocated for it.
53 bool isSmall() const {
54 return BeginX == static_cast<const void*>(&FirstEl);
57 /// grow_pod - This is an implementation of the grow() method which only works
58 /// on POD-like data types and is out of line to reduce code duplication.
59 void grow_pod(size_t MinSizeInBytes, size_t TSize);
62 /// size_in_bytes - This returns size()*sizeof(T).
63 size_t size_in_bytes() const {
64 return size_t((char*)EndX - (char*)BeginX);
67 /// capacity_in_bytes - This returns capacity()*sizeof(T).
68 size_t capacity_in_bytes() const {
69 return size_t((char*)CapacityX - (char*)BeginX);
72 bool empty() const { return BeginX == EndX; }
77 class SmallVectorTemplateCommon : public SmallVectorBase {
79 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(Size) {}
81 void setEnd(T *P) { this->EndX = P; }
83 typedef size_t size_type;
84 typedef ptrdiff_t difference_type;
87 typedef const T *const_iterator;
89 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
90 typedef std::reverse_iterator<iterator> reverse_iterator;
93 typedef const T &const_reference;
95 typedef const T *const_pointer;
97 // forward iterator creation methods.
98 iterator begin() { return (iterator)this->BeginX; }
99 const_iterator begin() const { return (const_iterator)this->BeginX; }
100 iterator end() { return (iterator)this->EndX; }
101 const_iterator end() const { return (const_iterator)this->EndX; }
103 iterator capacity_ptr() { return (iterator)this->CapacityX; }
104 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
107 // reverse iterator creation methods.
108 reverse_iterator rbegin() { return reverse_iterator(end()); }
109 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
110 reverse_iterator rend() { return reverse_iterator(begin()); }
111 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
113 size_type size() const { return end()-begin(); }
114 size_type max_size() const { return size_type(-1) / sizeof(T); }
116 /// capacity - Return the total number of elements in the currently allocated
118 size_t capacity() const { return capacity_ptr() - begin(); }
120 /// data - Return a pointer to the vector's buffer, even if empty().
121 pointer data() { return pointer(begin()); }
122 /// data - Return a pointer to the vector's buffer, even if empty().
123 const_pointer data() const { return const_pointer(begin()); }
125 reference operator[](unsigned idx) {
126 assert(begin() + idx < end());
129 const_reference operator[](unsigned idx) const {
130 assert(begin() + idx < end());
137 const_reference front() const {
144 const_reference back() const {
149 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
150 /// implementations that are designed to work with non-POD-like T's.
151 template <typename T, bool isPodLike>
152 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
154 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
156 static void destroy_range(T *S, T *E) {
163 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
164 /// starting with "Dest", constructing elements into it as needed.
165 template<typename It1, typename It2>
166 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
167 std::uninitialized_copy(I, E, Dest);
170 /// grow - double the size of the allocated memory, guaranteeing space for at
171 /// least one more element or MinSize if specified.
172 void grow(size_t MinSize = 0);
175 void push_back(const T &Elt) {
176 if (this->EndX < this->CapacityX) {
178 new (this->end()) T(Elt);
179 this->setEnd(this->end()+1);
187 this->setEnd(this->end()-1);
192 // Define this out-of-line to dissuade the C++ compiler from inlining it.
193 template <typename T, bool isPodLike>
194 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
195 size_t CurCapacity = this->capacity();
196 size_t CurSize = this->size();
197 size_t NewCapacity = 2*CurCapacity + 1; // Always grow, even from zero.
198 if (NewCapacity < MinSize)
199 NewCapacity = MinSize;
200 T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));
202 // Copy the elements over.
203 this->uninitialized_copy(this->begin(), this->end(), NewElts);
205 // Destroy the original elements.
206 destroy_range(this->begin(), this->end());
208 // If this wasn't grown from the inline copy, deallocate the old space.
209 if (!this->isSmall())
212 this->setEnd(NewElts+CurSize);
213 this->BeginX = NewElts;
214 this->CapacityX = this->begin()+NewCapacity;
218 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
219 /// implementations that are designed to work with POD-like T's.
220 template <typename T>
221 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
223 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
225 // No need to do a destroy loop for POD's.
226 static void destroy_range(T *, T *) {}
228 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
229 /// starting with "Dest", constructing elements into it as needed.
230 template<typename It1, typename It2>
231 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
232 // Arbitrary iterator types; just use the basic implementation.
233 std::uninitialized_copy(I, E, Dest);
236 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
237 /// starting with "Dest", constructing elements into it as needed.
238 template<typename T1, typename T2>
239 static void uninitialized_copy(T1 *I, T1 *E, T2 *Dest) {
240 // Use memcpy for PODs iterated by pointers (which includes SmallVector
241 // iterators): std::uninitialized_copy optimizes to memmove, but we can
243 memcpy(Dest, I, (E-I)*sizeof(T));
246 /// grow - double the size of the allocated memory, guaranteeing space for at
247 /// least one more element or MinSize if specified.
248 void grow(size_t MinSize = 0) {
249 this->grow_pod(MinSize*sizeof(T), sizeof(T));
252 void push_back(const T &Elt) {
253 if (this->EndX < this->CapacityX) {
256 this->setEnd(this->end()+1);
264 this->setEnd(this->end()-1);
269 /// SmallVectorImpl - This class consists of common code factored out of the
270 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
271 /// template parameter.
272 template <typename T>
273 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
274 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
276 SmallVectorImpl(const SmallVectorImpl&); // DISABLED.
278 typedef typename SuperClass::iterator iterator;
279 typedef typename SuperClass::size_type size_type;
282 // Default ctor - Initialize to empty.
283 explicit SmallVectorImpl(unsigned N)
284 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
289 // Destroy the constructed elements in the vector.
290 this->destroy_range(this->begin(), this->end());
292 // If this wasn't grown from the inline copy, deallocate the old space.
293 if (!this->isSmall())
299 this->destroy_range(this->begin(), this->end());
300 this->EndX = this->BeginX;
303 void resize(unsigned N) {
304 if (N < this->size()) {
305 this->destroy_range(this->begin()+N, this->end());
306 this->setEnd(this->begin()+N);
307 } else if (N > this->size()) {
308 if (this->capacity() < N)
310 std::uninitialized_fill(this->end(), this->begin()+N, T());
311 this->setEnd(this->begin()+N);
315 void resize(unsigned N, const T &NV) {
316 if (N < this->size()) {
317 this->destroy_range(this->begin()+N, this->end());
318 this->setEnd(this->begin()+N);
319 } else if (N > this->size()) {
320 if (this->capacity() < N)
322 std::uninitialized_fill(this->end(), this->begin()+N, NV);
323 this->setEnd(this->begin()+N);
327 void reserve(unsigned N) {
328 if (this->capacity() < N)
333 T Result = this->back();
338 void swap(SmallVectorImpl &RHS);
340 /// append - Add the specified range to the end of the SmallVector.
342 template<typename in_iter>
343 void append(in_iter in_start, in_iter in_end) {
344 size_type NumInputs = std::distance(in_start, in_end);
345 // Grow allocated space if needed.
346 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
347 this->grow(this->size()+NumInputs);
349 // Copy the new elements over.
350 // TODO: NEED To compile time dispatch on whether in_iter is a random access
351 // iterator to use the fast uninitialized_copy.
352 std::uninitialized_copy(in_start, in_end, this->end());
353 this->setEnd(this->end() + NumInputs);
356 /// append - Add the specified range to the end of the SmallVector.
358 void append(size_type NumInputs, const T &Elt) {
359 // Grow allocated space if needed.
360 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
361 this->grow(this->size()+NumInputs);
363 // Copy the new elements over.
364 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
365 this->setEnd(this->end() + NumInputs);
368 void assign(unsigned NumElts, const T &Elt) {
370 if (this->capacity() < NumElts)
372 this->setEnd(this->begin()+NumElts);
373 std::uninitialized_fill(this->begin(), this->end(), Elt);
376 iterator erase(iterator I) {
378 // Shift all elts down one.
379 std::copy(I+1, this->end(), I);
380 // Drop the last elt.
385 iterator erase(iterator S, iterator E) {
387 // Shift all elts down.
388 iterator I = std::copy(E, this->end(), S);
389 // Drop the last elts.
390 this->destroy_range(I, this->end());
395 iterator insert(iterator I, const T &Elt) {
396 if (I == this->end()) { // Important special case for empty vector.
397 this->push_back(Elt);
398 return this->end()-1;
401 if (this->EndX < this->CapacityX) {
403 new (this->end()) T(this->back());
404 this->setEnd(this->end()+1);
405 // Push everything else over.
406 std::copy_backward(I, this->end()-1, this->end());
408 // If we just moved the element we're inserting, be sure to update
410 const T *EltPtr = &Elt;
411 if (I <= EltPtr && EltPtr < this->EndX)
417 size_t EltNo = I-this->begin();
419 I = this->begin()+EltNo;
423 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
424 if (I == this->end()) { // Important special case for empty vector.
425 append(NumToInsert, Elt);
426 return this->end()-1;
429 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
430 size_t InsertElt = I - this->begin();
432 // Ensure there is enough space.
433 reserve(static_cast<unsigned>(this->size() + NumToInsert));
435 // Uninvalidate the iterator.
436 I = this->begin()+InsertElt;
438 // If there are more elements between the insertion point and the end of the
439 // range than there are being inserted, we can use a simple approach to
440 // insertion. Since we already reserved space, we know that this won't
441 // reallocate the vector.
442 if (size_t(this->end()-I) >= NumToInsert) {
443 T *OldEnd = this->end();
444 append(this->end()-NumToInsert, this->end());
446 // Copy the existing elements that get replaced.
447 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
449 std::fill_n(I, NumToInsert, Elt);
453 // Otherwise, we're inserting more elements than exist already, and we're
454 // not inserting at the end.
456 // Copy over the elements that we're about to overwrite.
457 T *OldEnd = this->end();
458 this->setEnd(this->end() + NumToInsert);
459 size_t NumOverwritten = OldEnd-I;
460 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
462 // Replace the overwritten part.
463 std::fill_n(I, NumOverwritten, Elt);
465 // Insert the non-overwritten middle part.
466 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
470 template<typename ItTy>
471 iterator insert(iterator I, ItTy From, ItTy To) {
472 if (I == this->end()) { // Important special case for empty vector.
474 return this->end()-1;
477 size_t NumToInsert = std::distance(From, To);
478 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
479 size_t InsertElt = I - this->begin();
481 // Ensure there is enough space.
482 reserve(static_cast<unsigned>(this->size() + NumToInsert));
484 // Uninvalidate the iterator.
485 I = this->begin()+InsertElt;
487 // If there are more elements between the insertion point and the end of the
488 // range than there are being inserted, we can use a simple approach to
489 // insertion. Since we already reserved space, we know that this won't
490 // reallocate the vector.
491 if (size_t(this->end()-I) >= NumToInsert) {
492 T *OldEnd = this->end();
493 append(this->end()-NumToInsert, this->end());
495 // Copy the existing elements that get replaced.
496 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
498 std::copy(From, To, I);
502 // Otherwise, we're inserting more elements than exist already, and we're
503 // not inserting at the end.
505 // Copy over the elements that we're about to overwrite.
506 T *OldEnd = this->end();
507 this->setEnd(this->end() + NumToInsert);
508 size_t NumOverwritten = OldEnd-I;
509 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
511 // Replace the overwritten part.
512 for (; NumOverwritten > 0; --NumOverwritten) {
517 // Insert the non-overwritten middle part.
518 this->uninitialized_copy(From, To, OldEnd);
522 const SmallVectorImpl
523 &operator=(const SmallVectorImpl &RHS);
525 bool operator==(const SmallVectorImpl &RHS) const {
526 if (this->size() != RHS.size()) return false;
527 return std::equal(this->begin(), this->end(), RHS.begin());
529 bool operator!=(const SmallVectorImpl &RHS) const {
530 return !(*this == RHS);
533 bool operator<(const SmallVectorImpl &RHS) const {
534 return std::lexicographical_compare(this->begin(), this->end(),
535 RHS.begin(), RHS.end());
538 /// set_size - Set the array size to \arg N, which the current array must have
539 /// enough capacity for.
541 /// This does not construct or destroy any elements in the vector.
543 /// Clients can use this in conjunction with capacity() to write past the end
544 /// of the buffer when they know that more elements are available, and only
545 /// update the size later. This avoids the cost of value initializing elements
546 /// which will only be overwritten.
547 void set_size(unsigned N) {
548 assert(N <= this->capacity());
549 this->setEnd(this->begin() + N);
554 template <typename T>
555 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
556 if (this == &RHS) return;
558 // We can only avoid copying elements if neither vector is small.
559 if (!this->isSmall() && !RHS.isSmall()) {
560 std::swap(this->BeginX, RHS.BeginX);
561 std::swap(this->EndX, RHS.EndX);
562 std::swap(this->CapacityX, RHS.CapacityX);
565 if (RHS.size() > this->capacity())
566 this->grow(RHS.size());
567 if (this->size() > RHS.capacity())
568 RHS.grow(this->size());
570 // Swap the shared elements.
571 size_t NumShared = this->size();
572 if (NumShared > RHS.size()) NumShared = RHS.size();
573 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
574 std::swap((*this)[i], RHS[i]);
576 // Copy over the extra elts.
577 if (this->size() > RHS.size()) {
578 size_t EltDiff = this->size() - RHS.size();
579 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
580 RHS.setEnd(RHS.end()+EltDiff);
581 this->destroy_range(this->begin()+NumShared, this->end());
582 this->setEnd(this->begin()+NumShared);
583 } else if (RHS.size() > this->size()) {
584 size_t EltDiff = RHS.size() - this->size();
585 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
586 this->setEnd(this->end() + EltDiff);
587 this->destroy_range(RHS.begin()+NumShared, RHS.end());
588 RHS.setEnd(RHS.begin()+NumShared);
592 template <typename T>
593 const SmallVectorImpl<T> &SmallVectorImpl<T>::
594 operator=(const SmallVectorImpl<T> &RHS) {
595 // Avoid self-assignment.
596 if (this == &RHS) return *this;
598 // If we already have sufficient space, assign the common elements, then
599 // destroy any excess.
600 size_t RHSSize = RHS.size();
601 size_t CurSize = this->size();
602 if (CurSize >= RHSSize) {
603 // Assign common elements.
606 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
608 NewEnd = this->begin();
610 // Destroy excess elements.
611 this->destroy_range(NewEnd, this->end());
614 this->setEnd(NewEnd);
618 // If we have to grow to have enough elements, destroy the current elements.
619 // This allows us to avoid copying them during the grow.
620 if (this->capacity() < RHSSize) {
621 // Destroy current elements.
622 this->destroy_range(this->begin(), this->end());
623 this->setEnd(this->begin());
626 } else if (CurSize) {
627 // Otherwise, use assignment for the already-constructed elements.
628 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
631 // Copy construct the new elements in place.
632 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
633 this->begin()+CurSize);
636 this->setEnd(this->begin()+RHSSize);
641 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
642 /// for the case when the array is small. It contains some number of elements
643 /// in-place, which allows it to avoid heap allocation when the actual number of
644 /// elements is below that threshold. This allows normal "small" cases to be
645 /// fast without losing generality for large inputs.
647 /// Note that this does not attempt to be exception safe.
649 template <typename T, unsigned N>
650 class SmallVector : public SmallVectorImpl<T> {
651 /// InlineElts - These are 'N-1' elements that are stored inline in the body
652 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
653 typedef typename SmallVectorImpl<T>::U U;
655 // MinUs - The number of U's require to cover N T's.
656 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
657 static_cast<unsigned int>(sizeof(U)) - 1) /
658 static_cast<unsigned int>(sizeof(U)),
660 // NumInlineEltsElts - The number of elements actually in this array. There
661 // is already one in the parent class, and we have to round up to avoid
662 // having a zero-element array.
663 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
665 // NumTsAvailable - The number of T's we actually have space for, which may
666 // be more than N due to rounding.
667 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
668 static_cast<unsigned int>(sizeof(T))
670 U InlineElts[NumInlineEltsElts];
672 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
675 explicit SmallVector(unsigned Size, const T &Value = T())
676 : SmallVectorImpl<T>(NumTsAvailable) {
677 this->assign(Size, Value);
680 template<typename ItTy>
681 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
685 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
687 SmallVectorImpl<T>::operator=(RHS);
690 const SmallVector &operator=(const SmallVector &RHS) {
691 SmallVectorImpl<T>::operator=(RHS);
697 /// Specialize SmallVector at N=0. This specialization guarantees
698 /// that it can be instantiated at an incomplete T if none of its
699 /// members are required.
700 template <typename T>
701 class SmallVector<T,0> : public SmallVectorImpl<T> {
703 SmallVector() : SmallVectorImpl<T>(0) {}
705 explicit SmallVector(unsigned Size, const T &Value = T())
706 : SmallVectorImpl<T>(0) {
707 this->assign(Size, Value);
710 template<typename ItTy>
711 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(0) {
715 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(0) {
716 SmallVectorImpl<T>::operator=(RHS);
719 SmallVector &operator=(const SmallVectorImpl<T> &RHS) {
720 return SmallVectorImpl<T>::operator=(RHS);
725 template<typename T, unsigned N>
726 static inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
727 return X.capacity_in_bytes();
730 } // End llvm namespace
733 /// Implement std::swap in terms of SmallVector swap.
736 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
740 /// Implement std::swap in terms of SmallVector swap.
741 template<typename T, unsigned N>
743 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {