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 char X __attribute__((aligned));
72 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
75 SmallVectorBase(size_t Size)
76 : BeginX(&FirstEl), EndX(&FirstEl), CapacityX((char*)&FirstEl+Size) {}
78 /// isSmall - Return true if this is a smallvector which has not had dynamic
79 /// memory allocated for it.
80 bool isSmall() const {
81 return BeginX == static_cast<const void*>(&FirstEl);
84 /// size_in_bytes - This returns size()*sizeof(T).
85 size_t size_in_bytes() const {
86 return size_t((char*)EndX - (char*)BeginX);
89 /// capacity_in_bytes - This returns capacity()*sizeof(T).
90 size_t capacity_in_bytes() const {
91 return size_t((char*)CapacityX - (char*)BeginX);
94 /// grow_pod - This is an implementation of the grow() method which only works
95 /// on POD-like datatypes and is out of line to reduce code duplication.
96 void grow_pod(size_t MinSizeInBytes, size_t TSize);
99 bool empty() const { return BeginX == EndX; }
103 template <typename T>
104 class SmallVectorTemplateCommon : public SmallVectorBase {
106 void setEnd(T *P) { this->EndX = P; }
108 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(Size) {}
110 typedef size_t size_type;
111 typedef ptrdiff_t difference_type;
112 typedef T value_type;
114 typedef const T *const_iterator;
116 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
117 typedef std::reverse_iterator<iterator> reverse_iterator;
119 typedef T &reference;
120 typedef const T &const_reference;
122 typedef const T *const_pointer;
124 // forward iterator creation methods.
125 iterator begin() { return (iterator)this->BeginX; }
126 const_iterator begin() const { return (const_iterator)this->BeginX; }
127 iterator end() { return (iterator)this->EndX; }
128 const_iterator end() const { return (const_iterator)this->EndX; }
130 iterator capacity_ptr() { return (iterator)this->CapacityX; }
131 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
134 // reverse iterator creation methods.
135 reverse_iterator rbegin() { return reverse_iterator(end()); }
136 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
137 reverse_iterator rend() { return reverse_iterator(begin()); }
138 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
140 size_type size() const { return end()-begin(); }
141 size_type max_size() const { return size_type(-1) / sizeof(T); }
143 /// capacity - Return the total number of elements in the currently allocated
145 size_t capacity() const { return capacity_ptr() - begin(); }
147 /// data - Return a pointer to the vector's buffer, even if empty().
148 pointer data() { return pointer(begin()); }
149 /// data - Return a pointer to the vector's buffer, even if empty().
150 const_pointer data() const { return const_pointer(begin()); }
152 reference operator[](unsigned idx) {
153 assert(begin() + idx < end());
156 const_reference operator[](unsigned idx) const {
157 assert(begin() + idx < end());
164 const_reference front() const {
171 const_reference back() const {
176 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
177 /// implementations that are designed to work with non-POD-like T's.
178 template <typename T, bool isPodLike>
179 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
181 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
183 static void destroy_range(T *S, T *E) {
190 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
191 /// starting with "Dest", constructing elements into it as needed.
192 template<typename It1, typename It2>
193 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
194 std::uninitialized_copy(I, E, Dest);
197 /// grow - double the size of the allocated memory, guaranteeing space for at
198 /// least one more element or MinSize if specified.
199 void grow(size_t MinSize = 0);
202 // Define this out-of-line to dissuade the C++ compiler from inlining it.
203 template <typename T, bool isPodLike>
204 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
205 size_t CurCapacity = this->capacity();
206 size_t CurSize = this->size();
207 size_t NewCapacity = 2*CurCapacity;
208 if (NewCapacity < MinSize)
209 NewCapacity = MinSize;
210 T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T)));
212 // Copy the elements over.
213 this->uninitialized_copy(this->begin(), this->end(), NewElts);
215 // Destroy the original elements.
216 destroy_range(this->begin(), this->end());
218 // If this wasn't grown from the inline copy, deallocate the old space.
219 if (!this->isSmall())
220 operator delete(this->begin());
222 this->setEnd(NewElts+CurSize);
223 this->BeginX = NewElts;
224 this->CapacityX = this->begin()+NewCapacity;
228 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
229 /// implementations that are designed to work with POD-like T's.
230 template <typename T>
231 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
233 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
235 // No need to do a destroy loop for POD's.
236 static void destroy_range(T *, T *) {}
238 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
239 /// starting with "Dest", constructing elements into it as needed.
240 template<typename It1, typename It2>
241 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
242 // Arbitrary iterator types; just use the basic implementation.
243 std::uninitialized_copy(I, E, Dest);
246 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
247 /// starting with "Dest", constructing elements into it as needed.
248 template<typename T1, typename T2>
249 static void uninitialized_copy(T1 *I, T1 *E, T2 *Dest) {
250 // Use memcpy for PODs iterated by pointers (which includes SmallVector
251 // iterators): std::uninitialized_copy optimizes to memmove, but we can
253 memcpy(Dest, I, (E-I)*sizeof(T));
256 /// grow - double the size of the allocated memory, guaranteeing space for at
257 /// least one more element or MinSize if specified.
258 void grow(size_t MinSize = 0) {
259 this->grow_pod(MinSize*sizeof(T), sizeof(T));
264 /// SmallVectorImpl - This class consists of common code factored out of the
265 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
266 /// template parameter.
267 template <typename T>
268 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
269 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
271 typedef typename SuperClass::iterator iterator;
272 typedef typename SuperClass::size_type size_type;
274 // Default ctor - Initialize to empty.
275 explicit SmallVectorImpl(unsigned N)
276 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
280 // Destroy the constructed elements in the vector.
281 this->destroy_range(this->begin(), this->end());
283 // If this wasn't grown from the inline copy, deallocate the old space.
284 if (!this->isSmall())
285 operator delete(this->begin());
290 this->destroy_range(this->begin(), this->end());
291 this->EndX = this->BeginX;
294 void resize(unsigned N) {
295 if (N < this->size()) {
296 this->destroy_range(this->begin()+N, this->end());
297 this->setEnd(this->begin()+N);
298 } else if (N > this->size()) {
299 if (this->capacity() < N)
301 this->construct_range(this->end(), this->begin()+N, T());
302 this->setEnd(this->begin()+N);
306 void resize(unsigned N, const T &NV) {
307 if (N < this->size()) {
308 this->destroy_range(this->begin()+N, this->end());
309 this->setEnd(this->begin()+N);
310 } else if (N > this->size()) {
311 if (this->capacity() < N)
313 construct_range(this->end(), this->begin()+N, NV);
314 this->setEnd(this->begin()+N);
318 void reserve(unsigned N) {
319 if (this->capacity() < N)
323 void push_back(const T &Elt) {
324 if (this->EndX < this->CapacityX) {
326 new (this->end()) T(Elt);
327 this->setEnd(this->end()+1);
335 this->setEnd(this->end()-1);
340 T Result = this->back();
346 void swap(SmallVectorImpl &RHS);
348 /// append - Add the specified range to the end of the SmallVector.
350 template<typename in_iter>
351 void append(in_iter in_start, in_iter in_end) {
352 size_type NumInputs = std::distance(in_start, in_end);
353 // Grow allocated space if needed.
354 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
355 this->grow(this->size()+NumInputs);
357 // Copy the new elements over.
358 // TODO: NEED To compile time dispatch on whether in_iter is a random access
359 // iterator to use the fast uninitialized_copy.
360 std::uninitialized_copy(in_start, in_end, this->end());
361 this->setEnd(this->end() + NumInputs);
364 /// append - Add the specified range to the end of the SmallVector.
366 void append(size_type NumInputs, const T &Elt) {
367 // Grow allocated space if needed.
368 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
369 this->grow(this->size()+NumInputs);
371 // Copy the new elements over.
372 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
373 this->setEnd(this->end() + NumInputs);
376 void assign(unsigned NumElts, const T &Elt) {
378 if (this->capacity() < NumElts)
380 this->setEnd(this->begin()+NumElts);
381 construct_range(this->begin(), this->end(), Elt);
384 iterator erase(iterator I) {
386 // Shift all elts down one.
387 std::copy(I+1, this->end(), I);
388 // Drop the last elt.
393 iterator erase(iterator S, iterator E) {
395 // Shift all elts down.
396 iterator I = std::copy(E, this->end(), S);
397 // Drop the last elts.
398 this->destroy_range(I, this->end());
403 iterator insert(iterator I, const T &Elt) {
404 if (I == this->end()) { // Important special case for empty vector.
406 return this->end()-1;
409 if (this->EndX < this->CapacityX) {
411 new (this->end()) T(this->back());
412 this->setEnd(this->end()+1);
413 // Push everything else over.
414 std::copy_backward(I, this->end()-1, this->end());
418 size_t EltNo = I-this->begin();
420 I = this->begin()+EltNo;
424 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
425 if (I == this->end()) { // Important special case for empty vector.
426 append(NumToInsert, Elt);
427 return this->end()-1;
430 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
431 size_t InsertElt = I - this->begin();
433 // Ensure there is enough space.
434 reserve(static_cast<unsigned>(this->size() + NumToInsert));
436 // Uninvalidate the iterator.
437 I = this->begin()+InsertElt;
439 // If there are more elements between the insertion point and the end of the
440 // range than there are being inserted, we can use a simple approach to
441 // insertion. Since we already reserved space, we know that this won't
442 // reallocate the vector.
443 if (size_t(this->end()-I) >= NumToInsert) {
444 T *OldEnd = this->end();
445 append(this->end()-NumToInsert, this->end());
447 // Copy the existing elements that get replaced.
448 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
450 std::fill_n(I, NumToInsert, Elt);
454 // Otherwise, we're inserting more elements than exist already, and we're
455 // not inserting at the end.
457 // Copy over the elements that we're about to overwrite.
458 T *OldEnd = this->end();
459 this->setEnd(this->end() + NumToInsert);
460 size_t NumOverwritten = OldEnd-I;
461 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
463 // Replace the overwritten part.
464 std::fill_n(I, NumOverwritten, Elt);
466 // Insert the non-overwritten middle part.
467 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
471 template<typename ItTy>
472 iterator insert(iterator I, ItTy From, ItTy To) {
473 if (I == this->end()) { // Important special case for empty vector.
475 return this->end()-1;
478 size_t NumToInsert = std::distance(From, To);
479 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
480 size_t InsertElt = I - this->begin();
482 // Ensure there is enough space.
483 reserve(static_cast<unsigned>(this->size() + NumToInsert));
485 // Uninvalidate the iterator.
486 I = this->begin()+InsertElt;
488 // If there are more elements between the insertion point and the end of the
489 // range than there are being inserted, we can use a simple approach to
490 // insertion. Since we already reserved space, we know that this won't
491 // reallocate the vector.
492 if (size_t(this->end()-I) >= NumToInsert) {
493 T *OldEnd = this->end();
494 append(this->end()-NumToInsert, this->end());
496 // Copy the existing elements that get replaced.
497 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
499 std::copy(From, To, I);
503 // Otherwise, we're inserting more elements than exist already, and we're
504 // not inserting at the end.
506 // Copy over the elements that we're about to overwrite.
507 T *OldEnd = this->end();
508 this->setEnd(this->end() + NumToInsert);
509 size_t NumOverwritten = OldEnd-I;
510 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
512 // Replace the overwritten part.
513 for (; NumOverwritten > 0; --NumOverwritten) {
518 // Insert the non-overwritten middle part.
519 this->uninitialized_copy(From, To, OldEnd);
523 const SmallVectorImpl
524 &operator=(const SmallVectorImpl &RHS);
526 bool operator==(const SmallVectorImpl &RHS) const {
527 if (this->size() != RHS.size()) return false;
528 return std::equal(this->begin(), this->end(), RHS.begin());
530 bool operator!=(const SmallVectorImpl &RHS) const {
531 return !(*this == RHS);
534 bool operator<(const SmallVectorImpl &RHS) const {
535 return std::lexicographical_compare(this->begin(), this->end(),
536 RHS.begin(), RHS.end());
539 /// set_size - Set the array size to \arg N, which the current array must have
540 /// enough capacity for.
542 /// This does not construct or destroy any elements in the vector.
544 /// Clients can use this in conjunction with capacity() to write past the end
545 /// of the buffer when they know that more elements are available, and only
546 /// update the size later. This avoids the cost of value initializing elements
547 /// which will only be overwritten.
548 void set_size(unsigned N) {
549 assert(N <= this->capacity());
550 this->setEnd(this->begin() + N);
554 static void construct_range(T *S, T *E, const T &Elt) {
561 template <typename T>
562 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
563 if (this == &RHS) return;
565 // We can only avoid copying elements if neither vector is small.
566 if (!this->isSmall() && !RHS.isSmall()) {
567 std::swap(this->BeginX, RHS.BeginX);
568 std::swap(this->EndX, RHS.EndX);
569 std::swap(this->CapacityX, RHS.CapacityX);
572 if (RHS.size() > this->capacity())
573 this->grow(RHS.size());
574 if (this->size() > RHS.capacity())
575 RHS.grow(this->size());
577 // Swap the shared elements.
578 size_t NumShared = this->size();
579 if (NumShared > RHS.size()) NumShared = RHS.size();
580 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
581 std::swap((*this)[i], RHS[i]);
583 // Copy over the extra elts.
584 if (this->size() > RHS.size()) {
585 size_t EltDiff = this->size() - RHS.size();
586 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
587 RHS.setEnd(RHS.end()+EltDiff);
588 this->destroy_range(this->begin()+NumShared, this->end());
589 this->setEnd(this->begin()+NumShared);
590 } else if (RHS.size() > this->size()) {
591 size_t EltDiff = RHS.size() - this->size();
592 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
593 this->setEnd(this->end() + EltDiff);
594 this->destroy_range(RHS.begin()+NumShared, RHS.end());
595 RHS.setEnd(RHS.begin()+NumShared);
599 template <typename T>
600 const SmallVectorImpl<T> &SmallVectorImpl<T>::
601 operator=(const SmallVectorImpl<T> &RHS) {
602 // Avoid self-assignment.
603 if (this == &RHS) return *this;
605 // If we already have sufficient space, assign the common elements, then
606 // destroy any excess.
607 size_t RHSSize = RHS.size();
608 size_t CurSize = this->size();
609 if (CurSize >= RHSSize) {
610 // Assign common elements.
613 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
615 NewEnd = this->begin();
617 // Destroy excess elements.
618 this->destroy_range(NewEnd, this->end());
621 this->setEnd(NewEnd);
625 // If we have to grow to have enough elements, destroy the current elements.
626 // This allows us to avoid copying them during the grow.
627 if (this->capacity() < RHSSize) {
628 // Destroy current elements.
629 this->destroy_range(this->begin(), this->end());
630 this->setEnd(this->begin());
633 } else if (CurSize) {
634 // Otherwise, use assignment for the already-constructed elements.
635 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
638 // Copy construct the new elements in place.
639 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
640 this->begin()+CurSize);
643 this->setEnd(this->begin()+RHSSize);
648 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
649 /// for the case when the array is small. It contains some number of elements
650 /// in-place, which allows it to avoid heap allocation when the actual number of
651 /// elements is below that threshold. This allows normal "small" cases to be
652 /// fast without losing generality for large inputs.
654 /// Note that this does not attempt to be exception safe.
656 template <typename T, unsigned N>
657 class SmallVector : public SmallVectorImpl<T> {
658 /// InlineElts - These are 'N-1' elements that are stored inline in the body
659 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
660 typedef typename SmallVectorImpl<T>::U U;
662 // MinUs - The number of U's require to cover N T's.
663 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
664 static_cast<unsigned int>(sizeof(U)) - 1) /
665 static_cast<unsigned int>(sizeof(U)),
667 // NumInlineEltsElts - The number of elements actually in this array. There
668 // is already one in the parent class, and we have to round up to avoid
669 // having a zero-element array.
670 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
672 // NumTsAvailable - The number of T's we actually have space for, which may
673 // be more than N due to rounding.
674 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
675 static_cast<unsigned int>(sizeof(T))
677 U InlineElts[NumInlineEltsElts];
679 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
682 explicit SmallVector(unsigned Size, const T &Value = T())
683 : SmallVectorImpl<T>(NumTsAvailable) {
686 this->push_back(Value);
689 template<typename ItTy>
690 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
694 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
696 SmallVectorImpl<T>::operator=(RHS);
699 const SmallVector &operator=(const SmallVector &RHS) {
700 SmallVectorImpl<T>::operator=(RHS);
706 } // End llvm namespace
709 /// Implement std::swap in terms of SmallVector swap.
712 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
716 /// Implement std::swap in terms of SmallVector swap.
717 template<typename T, unsigned N>
719 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {