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"
26 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
27 // additional overloads so that elements with pointer types are recognized as
28 // scalars and not objects, causing bizarre type conversion errors.
29 template<class T1, class T2>
30 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
31 _Scalar_ptr_iterator_tag _Cat;
35 template<class T1, class T2>
36 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
37 _Scalar_ptr_iterator_tag _Cat;
41 // FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
42 // is that the above hack won't work if it wasn't fixed.
49 /// SmallVectorBase - This is all the non-templated stuff common to all
51 class SmallVectorBase {
53 void *BeginX, *EndX, *CapacityX;
55 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
56 // don't want it to be automatically run, so we need to represent the space as
57 // something else. An array of char would work great, but might not be
58 // aligned sufficiently. Instead, we either use GCC extensions, or some
59 // number of union instances for the space, which guarantee maximal alignment.
62 U FirstEl __attribute__((aligned));
71 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
74 SmallVectorBase(size_t Size)
75 : BeginX(&FirstEl), EndX(&FirstEl), CapacityX((char*)&FirstEl+Size) {}
77 /// isSmall - Return true if this is a smallvector which has not had dynamic
78 /// memory allocated for it.
79 bool isSmall() const {
80 return BeginX == static_cast<const void*>(&FirstEl);
84 bool empty() const { return BeginX == EndX; }
88 class SmallVectorTemplateCommon : public SmallVectorBase {
90 void setEnd(T *P) { this->EndX = P; }
92 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(Size) {}
94 typedef size_t size_type;
95 typedef ptrdiff_t difference_type;
98 typedef const T *const_iterator;
100 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
101 typedef std::reverse_iterator<iterator> reverse_iterator;
103 typedef T &reference;
104 typedef const T &const_reference;
106 typedef const T *const_pointer;
108 // forward iterator creation methods.
109 iterator begin() { return (iterator)this->BeginX; }
110 const_iterator begin() const { return (const_iterator)this->BeginX; }
111 iterator end() { return (iterator)this->EndX; }
112 const_iterator end() const { return (const_iterator)this->EndX; }
114 iterator capacity_ptr() { return (iterator)this->CapacityX; }
115 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
118 // reverse iterator creation methods.
119 reverse_iterator rbegin() { return reverse_iterator(end()); }
120 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
121 reverse_iterator rend() { return reverse_iterator(begin()); }
122 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
124 size_type size() const { return end()-begin(); }
125 size_type max_size() const { return size_type(-1) / sizeof(T); }
127 /// capacity - Return the total number of elements in the currently allocated
129 size_t capacity() const { return capacity_ptr() - begin(); }
131 /// data - Return a pointer to the vector's buffer, even if empty().
132 pointer data() { return pointer(begin()); }
133 /// data - Return a pointer to the vector's buffer, even if empty().
134 const_pointer data() const { return const_pointer(begin()); }
136 reference operator[](unsigned idx) {
137 assert(begin() + idx < end());
140 const_reference operator[](unsigned idx) const {
141 assert(begin() + idx < end());
148 const_reference front() const {
155 const_reference back() const {
161 template <typename T, bool isPodLike>
162 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
164 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
168 template <typename T>
169 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
171 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
176 /// SmallVectorImpl - This class consists of common code factored out of the
177 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
178 /// template parameter.
179 template <typename T>
180 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
182 typedef typename SmallVectorTemplateBase<T, isPodLike<T>::value >::iterator
184 typedef typename SmallVectorTemplateBase<T, isPodLike<T>::value >::size_type
187 // Default ctor - Initialize to empty.
188 explicit SmallVectorImpl(unsigned N)
189 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
193 // Destroy the constructed elements in the vector.
194 destroy_range(this->begin(), this->end());
196 // If this wasn't grown from the inline copy, deallocate the old space.
197 if (!this->isSmall())
198 operator delete(this->begin());
203 destroy_range(this->begin(), this->end());
204 this->EndX = this->BeginX;
207 void resize(unsigned N) {
208 if (N < this->size()) {
209 this->destroy_range(this->begin()+N, this->end());
210 this->setEnd(this->begin()+N);
211 } else if (N > this->size()) {
212 if (this->capacity() < N)
214 this->construct_range(this->end(), this->begin()+N, T());
215 this->setEnd(this->begin()+N);
219 void resize(unsigned N, const T &NV) {
220 if (N < this->size()) {
221 destroy_range(this->begin()+N, this->end());
222 setEnd(this->begin()+N);
223 } else if (N > this->size()) {
224 if (this->capacity() < N)
226 construct_range(this->end(), this->begin()+N, NV);
227 setEnd(this->begin()+N);
231 void reserve(unsigned N) {
232 if (this->capacity() < N)
236 void push_back(const T &Elt) {
237 if (this->EndX < this->CapacityX) {
239 new (this->end()) T(Elt);
240 setEnd(this->end()+1);
248 setEnd(this->end()-1);
253 T Result = this->back();
259 void swap(SmallVectorImpl &RHS);
261 /// append - Add the specified range to the end of the SmallVector.
263 template<typename in_iter>
264 void append(in_iter in_start, in_iter in_end) {
265 size_type NumInputs = std::distance(in_start, in_end);
266 // Grow allocated space if needed.
267 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
268 grow(this->size()+NumInputs);
270 // Copy the new elements over.
271 // TODO: NEED To compile time dispatch on whether in_iter is a random access
272 // iterator to use the fast uninitialized_copy.
273 std::uninitialized_copy(in_start, in_end, this->end());
274 setEnd(this->end() + NumInputs);
277 /// append - Add the specified range to the end of the SmallVector.
279 void append(size_type NumInputs, const T &Elt) {
280 // Grow allocated space if needed.
281 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
282 grow(this->size()+NumInputs);
284 // Copy the new elements over.
285 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
286 setEnd(this->end() + NumInputs);
289 void assign(unsigned NumElts, const T &Elt) {
291 if (this->capacity() < NumElts)
293 setEnd(this->begin()+NumElts);
294 construct_range(this->begin(), this->end(), Elt);
297 iterator erase(iterator I) {
299 // Shift all elts down one.
300 std::copy(I+1, this->end(), I);
301 // Drop the last elt.
306 iterator erase(iterator S, iterator E) {
308 // Shift all elts down.
309 iterator I = std::copy(E, this->end(), S);
310 // Drop the last elts.
311 destroy_range(I, this->end());
316 iterator insert(iterator I, const T &Elt) {
317 if (I == this->end()) { // Important special case for empty vector.
319 return this->end()-1;
322 if (this->EndX < this->CapacityX) {
324 new (this->end()) T(this->back());
325 this->setEnd(this->end()+1);
326 // Push everything else over.
327 std::copy_backward(I, this->end()-1, this->end());
331 size_t EltNo = I-this->begin();
333 I = this->begin()+EltNo;
337 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
338 if (I == this->end()) { // Important special case for empty vector.
339 append(NumToInsert, Elt);
340 return this->end()-1;
343 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
344 size_t InsertElt = I - this->begin();
346 // Ensure there is enough space.
347 reserve(static_cast<unsigned>(this->size() + NumToInsert));
349 // Uninvalidate the iterator.
350 I = this->begin()+InsertElt;
352 // If there are more elements between the insertion point and the end of the
353 // range than there are being inserted, we can use a simple approach to
354 // insertion. Since we already reserved space, we know that this won't
355 // reallocate the vector.
356 if (size_t(this->end()-I) >= NumToInsert) {
357 T *OldEnd = this->end();
358 append(this->end()-NumToInsert, this->end());
360 // Copy the existing elements that get replaced.
361 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
363 std::fill_n(I, NumToInsert, Elt);
367 // Otherwise, we're inserting more elements than exist already, and we're
368 // not inserting at the end.
370 // Copy over the elements that we're about to overwrite.
371 T *OldEnd = this->end();
372 setEnd(this->end() + NumToInsert);
373 size_t NumOverwritten = OldEnd-I;
374 uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
376 // Replace the overwritten part.
377 std::fill_n(I, NumOverwritten, Elt);
379 // Insert the non-overwritten middle part.
380 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
384 template<typename ItTy>
385 iterator insert(iterator I, ItTy From, ItTy To) {
386 if (I == this->end()) { // Important special case for empty vector.
388 return this->end()-1;
391 size_t NumToInsert = std::distance(From, To);
392 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
393 size_t InsertElt = I - this->begin();
395 // Ensure there is enough space.
396 reserve(static_cast<unsigned>(this->size() + NumToInsert));
398 // Uninvalidate the iterator.
399 I = this->begin()+InsertElt;
401 // If there are more elements between the insertion point and the end of the
402 // range than there are being inserted, we can use a simple approach to
403 // insertion. Since we already reserved space, we know that this won't
404 // reallocate the vector.
405 if (size_t(this->end()-I) >= NumToInsert) {
406 T *OldEnd = this->end();
407 append(this->end()-NumToInsert, this->end());
409 // Copy the existing elements that get replaced.
410 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
412 std::copy(From, To, I);
416 // Otherwise, we're inserting more elements than exist already, and we're
417 // not inserting at the end.
419 // Copy over the elements that we're about to overwrite.
420 T *OldEnd = this->end();
421 setEnd(this->end() + NumToInsert);
422 size_t NumOverwritten = OldEnd-I;
423 uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
425 // Replace the overwritten part.
426 std::copy(From, From+NumOverwritten, I);
428 // Insert the non-overwritten middle part.
429 uninitialized_copy(From+NumOverwritten, To, OldEnd);
433 const SmallVectorImpl
434 &operator=(const SmallVectorImpl &RHS);
436 bool operator==(const SmallVectorImpl &RHS) const {
437 if (this->size() != RHS.size()) return false;
438 return std::equal(this->begin(), this->end(), RHS.begin());
440 bool operator!=(const SmallVectorImpl &RHS) const {
441 return !(*this == RHS);
444 bool operator<(const SmallVectorImpl &RHS) const {
445 return std::lexicographical_compare(this->begin(), this->end(),
446 RHS.begin(), RHS.end());
449 /// set_size - Set the array size to \arg N, which the current array must have
450 /// enough capacity for.
452 /// This does not construct or destroy any elements in the vector.
454 /// Clients can use this in conjunction with capacity() to write past the end
455 /// of the buffer when they know that more elements are available, and only
456 /// update the size later. This avoids the cost of value initializing elements
457 /// which will only be overwritten.
458 void set_size(unsigned N) {
459 assert(N <= this->capacity());
460 setEnd(this->begin() + N);
464 /// grow - double the size of the allocated memory, guaranteeing space for at
465 /// least one more element or MinSize if specified.
466 void grow(size_t MinSize = 0);
468 static void construct_range(T *S, T *E, const T &Elt) {
473 static void destroy_range(T *S, T *E) {
474 // No need to do a destroy loop for POD's.
475 if (isPodLike<T>::value) return;
483 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
484 /// starting with "Dest", constructing elements into it as needed.
485 template<typename It1, typename It2>
486 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
487 // Use memcpy for PODs: std::uninitialized_copy optimizes to memmove.
488 if (isPodLike<T>::value)
489 memcpy(&*Dest, &*I, (E-I)*sizeof(T));
491 std::uninitialized_copy(I, E, Dest);
496 // Define this out-of-line to dissuade the C++ compiler from inlining it.
497 template <typename T>
498 void SmallVectorImpl<T>::grow(size_t MinSize) {
499 size_t CurCapacity = this->capacity();
500 size_t CurSize = this->size();
501 size_t NewCapacity = 2*CurCapacity;
502 if (NewCapacity < MinSize)
503 NewCapacity = MinSize;
504 T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T)));
506 // Copy the elements over.
507 uninitialized_copy(this->begin(), this->end(), NewElts);
509 // Destroy the original elements.
510 destroy_range(this->begin(), this->end());
512 // If this wasn't grown from the inline copy, deallocate the old space.
513 if (!this->isSmall())
514 operator delete(this->begin());
516 setEnd(NewElts+CurSize);
517 this->BeginX = NewElts;
518 this->CapacityX = this->begin()+NewCapacity;
521 template <typename T>
522 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
523 if (this == &RHS) return;
525 // We can only avoid copying elements if neither vector is small.
526 if (!this->isSmall() && !RHS.isSmall()) {
527 std::swap(this->BeginX, RHS.BeginX);
528 std::swap(this->EndX, RHS.EndX);
529 std::swap(this->CapacityX, RHS.CapacityX);
532 if (RHS.size() > this->capacity())
534 if (this->size() > RHS.capacity())
535 RHS.grow(this->size());
537 // Swap the shared elements.
538 size_t NumShared = this->size();
539 if (NumShared > RHS.size()) NumShared = RHS.size();
540 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
541 std::swap((*this)[i], RHS[i]);
543 // Copy over the extra elts.
544 if (this->size() > RHS.size()) {
545 size_t EltDiff = this->size() - RHS.size();
546 uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
547 RHS.setEnd(RHS.end()+EltDiff);
548 destroy_range(this->begin()+NumShared, this->end());
549 setEnd(this->begin()+NumShared);
550 } else if (RHS.size() > this->size()) {
551 size_t EltDiff = RHS.size() - this->size();
552 uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
553 setEnd(this->end() + EltDiff);
554 destroy_range(RHS.begin()+NumShared, RHS.end());
555 RHS.setEnd(RHS.begin()+NumShared);
559 template <typename T>
560 const SmallVectorImpl<T> &SmallVectorImpl<T>::
561 operator=(const SmallVectorImpl<T> &RHS) {
562 // Avoid self-assignment.
563 if (this == &RHS) return *this;
565 // If we already have sufficient space, assign the common elements, then
566 // destroy any excess.
567 size_t RHSSize = RHS.size();
568 size_t CurSize = this->size();
569 if (CurSize >= RHSSize) {
570 // Assign common elements.
573 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
575 NewEnd = this->begin();
577 // Destroy excess elements.
578 destroy_range(NewEnd, this->end());
585 // If we have to grow to have enough elements, destroy the current elements.
586 // This allows us to avoid copying them during the grow.
587 if (this->capacity() < RHSSize) {
588 // Destroy current elements.
589 destroy_range(this->begin(), this->end());
590 setEnd(this->begin());
593 } else if (CurSize) {
594 // Otherwise, use assignment for the already-constructed elements.
595 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
598 // Copy construct the new elements in place.
599 uninitialized_copy(RHS.begin()+CurSize, RHS.end(), this->begin()+CurSize);
602 setEnd(this->begin()+RHSSize);
607 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
608 /// for the case when the array is small. It contains some number of elements
609 /// in-place, which allows it to avoid heap allocation when the actual number of
610 /// elements is below that threshold. This allows normal "small" cases to be
611 /// fast without losing generality for large inputs.
613 /// Note that this does not attempt to be exception safe.
615 template <typename T, unsigned N>
616 class SmallVector : public SmallVectorImpl<T> {
617 /// InlineElts - These are 'N-1' elements that are stored inline in the body
618 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
619 typedef typename SmallVectorImpl<T>::U U;
621 // MinUs - The number of U's require to cover N T's.
622 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
623 static_cast<unsigned int>(sizeof(U)) - 1) /
624 static_cast<unsigned int>(sizeof(U)),
626 // NumInlineEltsElts - The number of elements actually in this array. There
627 // is already one in the parent class, and we have to round up to avoid
628 // having a zero-element array.
629 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
631 // NumTsAvailable - The number of T's we actually have space for, which may
632 // be more than N due to rounding.
633 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
634 static_cast<unsigned int>(sizeof(T))
636 U InlineElts[NumInlineEltsElts];
638 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
641 explicit SmallVector(unsigned Size, const T &Value = T())
642 : SmallVectorImpl<T>(NumTsAvailable) {
645 this->push_back(Value);
648 template<typename ItTy>
649 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
653 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
655 SmallVectorImpl<T>::operator=(RHS);
658 const SmallVector &operator=(const SmallVector &RHS) {
659 SmallVectorImpl<T>::operator=(RHS);
665 } // End llvm namespace
668 /// Implement std::swap in terms of SmallVector swap.
671 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
675 /// Implement std::swap in terms of SmallVector swap.
676 template<typename T, unsigned N>
678 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {