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 // Use memcpy for PODs: std::uninitialized_copy optimizes to memmove, memcpy
244 memcpy(&*Dest, &*I, (E-I)*sizeof(T));
247 /// grow - double the size of the allocated memory, guaranteeing space for at
248 /// least one more element or MinSize if specified.
249 void grow(size_t MinSize = 0) {
250 this->grow_pod(MinSize*sizeof(T), sizeof(T));
255 /// SmallVectorImpl - This class consists of common code factored out of the
256 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
257 /// template parameter.
258 template <typename T>
259 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
260 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
262 typedef typename SuperClass::iterator iterator;
263 typedef typename SuperClass::size_type size_type;
265 // Default ctor - Initialize to empty.
266 explicit SmallVectorImpl(unsigned N)
267 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
271 // Destroy the constructed elements in the vector.
272 this->destroy_range(this->begin(), this->end());
274 // If this wasn't grown from the inline copy, deallocate the old space.
275 if (!this->isSmall())
276 operator delete(this->begin());
281 this->destroy_range(this->begin(), this->end());
282 this->EndX = this->BeginX;
285 void resize(unsigned N) {
286 if (N < this->size()) {
287 this->destroy_range(this->begin()+N, this->end());
288 this->setEnd(this->begin()+N);
289 } else if (N > this->size()) {
290 if (this->capacity() < N)
292 this->construct_range(this->end(), this->begin()+N, T());
293 this->setEnd(this->begin()+N);
297 void resize(unsigned N, const T &NV) {
298 if (N < this->size()) {
299 this->destroy_range(this->begin()+N, this->end());
300 this->setEnd(this->begin()+N);
301 } else if (N > this->size()) {
302 if (this->capacity() < N)
304 construct_range(this->end(), this->begin()+N, NV);
305 this->setEnd(this->begin()+N);
309 void reserve(unsigned N) {
310 if (this->capacity() < N)
314 void push_back(const T &Elt) {
315 if (this->EndX < this->CapacityX) {
317 new (this->end()) T(Elt);
318 this->setEnd(this->end()+1);
326 this->setEnd(this->end()-1);
331 T Result = this->back();
337 void swap(SmallVectorImpl &RHS);
339 /// append - Add the specified range to the end of the SmallVector.
341 template<typename in_iter>
342 void append(in_iter in_start, in_iter in_end) {
343 size_type NumInputs = std::distance(in_start, in_end);
344 // Grow allocated space if needed.
345 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
346 this->grow(this->size()+NumInputs);
348 // Copy the new elements over.
349 // TODO: NEED To compile time dispatch on whether in_iter is a random access
350 // iterator to use the fast uninitialized_copy.
351 std::uninitialized_copy(in_start, in_end, this->end());
352 this->setEnd(this->end() + NumInputs);
355 /// append - Add the specified range to the end of the SmallVector.
357 void append(size_type NumInputs, const T &Elt) {
358 // Grow allocated space if needed.
359 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
360 this->grow(this->size()+NumInputs);
362 // Copy the new elements over.
363 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
364 this->setEnd(this->end() + NumInputs);
367 void assign(unsigned NumElts, const T &Elt) {
369 if (this->capacity() < NumElts)
371 this->setEnd(this->begin()+NumElts);
372 construct_range(this->begin(), this->end(), Elt);
375 iterator erase(iterator I) {
377 // Shift all elts down one.
378 std::copy(I+1, this->end(), I);
379 // Drop the last elt.
384 iterator erase(iterator S, iterator E) {
386 // Shift all elts down.
387 iterator I = std::copy(E, this->end(), S);
388 // Drop the last elts.
389 this->destroy_range(I, this->end());
394 iterator insert(iterator I, const T &Elt) {
395 if (I == this->end()) { // Important special case for empty vector.
397 return this->end()-1;
400 if (this->EndX < this->CapacityX) {
402 new (this->end()) T(this->back());
403 this->setEnd(this->end()+1);
404 // Push everything else over.
405 std::copy_backward(I, this->end()-1, this->end());
409 size_t EltNo = I-this->begin();
411 I = this->begin()+EltNo;
415 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
416 if (I == this->end()) { // Important special case for empty vector.
417 append(NumToInsert, Elt);
418 return this->end()-1;
421 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
422 size_t InsertElt = I - this->begin();
424 // Ensure there is enough space.
425 reserve(static_cast<unsigned>(this->size() + NumToInsert));
427 // Uninvalidate the iterator.
428 I = this->begin()+InsertElt;
430 // If there are more elements between the insertion point and the end of the
431 // range than there are being inserted, we can use a simple approach to
432 // insertion. Since we already reserved space, we know that this won't
433 // reallocate the vector.
434 if (size_t(this->end()-I) >= NumToInsert) {
435 T *OldEnd = this->end();
436 append(this->end()-NumToInsert, this->end());
438 // Copy the existing elements that get replaced.
439 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
441 std::fill_n(I, NumToInsert, Elt);
445 // Otherwise, we're inserting more elements than exist already, and we're
446 // not inserting at the end.
448 // Copy over the elements that we're about to overwrite.
449 T *OldEnd = this->end();
450 this->setEnd(this->end() + NumToInsert);
451 size_t NumOverwritten = OldEnd-I;
452 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
454 // Replace the overwritten part.
455 std::fill_n(I, NumOverwritten, Elt);
457 // Insert the non-overwritten middle part.
458 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
462 template<typename ItTy>
463 iterator insert(iterator I, ItTy From, ItTy To) {
464 if (I == this->end()) { // Important special case for empty vector.
466 return this->end()-1;
469 size_t NumToInsert = std::distance(From, To);
470 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
471 size_t InsertElt = I - this->begin();
473 // Ensure there is enough space.
474 reserve(static_cast<unsigned>(this->size() + NumToInsert));
476 // Uninvalidate the iterator.
477 I = this->begin()+InsertElt;
479 // If there are more elements between the insertion point and the end of the
480 // range than there are being inserted, we can use a simple approach to
481 // insertion. Since we already reserved space, we know that this won't
482 // reallocate the vector.
483 if (size_t(this->end()-I) >= NumToInsert) {
484 T *OldEnd = this->end();
485 append(this->end()-NumToInsert, this->end());
487 // Copy the existing elements that get replaced.
488 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
490 std::copy(From, To, I);
494 // Otherwise, we're inserting more elements than exist already, and we're
495 // not inserting at the end.
497 // Copy over the elements that we're about to overwrite.
498 T *OldEnd = this->end();
499 this->setEnd(this->end() + NumToInsert);
500 size_t NumOverwritten = OldEnd-I;
501 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
503 // Replace the overwritten part.
504 std::copy(From, From+NumOverwritten, I);
506 // Insert the non-overwritten middle part.
507 this->uninitialized_copy(From+NumOverwritten, To, OldEnd);
511 const SmallVectorImpl
512 &operator=(const SmallVectorImpl &RHS);
514 bool operator==(const SmallVectorImpl &RHS) const {
515 if (this->size() != RHS.size()) return false;
516 return std::equal(this->begin(), this->end(), RHS.begin());
518 bool operator!=(const SmallVectorImpl &RHS) const {
519 return !(*this == RHS);
522 bool operator<(const SmallVectorImpl &RHS) const {
523 return std::lexicographical_compare(this->begin(), this->end(),
524 RHS.begin(), RHS.end());
527 /// set_size - Set the array size to \arg N, which the current array must have
528 /// enough capacity for.
530 /// This does not construct or destroy any elements in the vector.
532 /// Clients can use this in conjunction with capacity() to write past the end
533 /// of the buffer when they know that more elements are available, and only
534 /// update the size later. This avoids the cost of value initializing elements
535 /// which will only be overwritten.
536 void set_size(unsigned N) {
537 assert(N <= this->capacity());
538 this->setEnd(this->begin() + N);
542 static void construct_range(T *S, T *E, const T &Elt) {
549 template <typename T>
550 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
551 if (this == &RHS) return;
553 // We can only avoid copying elements if neither vector is small.
554 if (!this->isSmall() && !RHS.isSmall()) {
555 std::swap(this->BeginX, RHS.BeginX);
556 std::swap(this->EndX, RHS.EndX);
557 std::swap(this->CapacityX, RHS.CapacityX);
560 if (RHS.size() > this->capacity())
561 this->grow(RHS.size());
562 if (this->size() > RHS.capacity())
563 RHS.grow(this->size());
565 // Swap the shared elements.
566 size_t NumShared = this->size();
567 if (NumShared > RHS.size()) NumShared = RHS.size();
568 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
569 std::swap((*this)[i], RHS[i]);
571 // Copy over the extra elts.
572 if (this->size() > RHS.size()) {
573 size_t EltDiff = this->size() - RHS.size();
574 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
575 RHS.setEnd(RHS.end()+EltDiff);
576 this->destroy_range(this->begin()+NumShared, this->end());
577 this->setEnd(this->begin()+NumShared);
578 } else if (RHS.size() > this->size()) {
579 size_t EltDiff = RHS.size() - this->size();
580 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
581 this->setEnd(this->end() + EltDiff);
582 this->destroy_range(RHS.begin()+NumShared, RHS.end());
583 RHS.setEnd(RHS.begin()+NumShared);
587 template <typename T>
588 const SmallVectorImpl<T> &SmallVectorImpl<T>::
589 operator=(const SmallVectorImpl<T> &RHS) {
590 // Avoid self-assignment.
591 if (this == &RHS) return *this;
593 // If we already have sufficient space, assign the common elements, then
594 // destroy any excess.
595 size_t RHSSize = RHS.size();
596 size_t CurSize = this->size();
597 if (CurSize >= RHSSize) {
598 // Assign common elements.
601 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
603 NewEnd = this->begin();
605 // Destroy excess elements.
606 this->destroy_range(NewEnd, this->end());
609 this->setEnd(NewEnd);
613 // If we have to grow to have enough elements, destroy the current elements.
614 // This allows us to avoid copying them during the grow.
615 if (this->capacity() < RHSSize) {
616 // Destroy current elements.
617 this->destroy_range(this->begin(), this->end());
618 this->setEnd(this->begin());
621 } else if (CurSize) {
622 // Otherwise, use assignment for the already-constructed elements.
623 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
626 // Copy construct the new elements in place.
627 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
628 this->begin()+CurSize);
631 this->setEnd(this->begin()+RHSSize);
636 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
637 /// for the case when the array is small. It contains some number of elements
638 /// in-place, which allows it to avoid heap allocation when the actual number of
639 /// elements is below that threshold. This allows normal "small" cases to be
640 /// fast without losing generality for large inputs.
642 /// Note that this does not attempt to be exception safe.
644 template <typename T, unsigned N>
645 class SmallVector : public SmallVectorImpl<T> {
646 /// InlineElts - These are 'N-1' elements that are stored inline in the body
647 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
648 typedef typename SmallVectorImpl<T>::U U;
650 // MinUs - The number of U's require to cover N T's.
651 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
652 static_cast<unsigned int>(sizeof(U)) - 1) /
653 static_cast<unsigned int>(sizeof(U)),
655 // NumInlineEltsElts - The number of elements actually in this array. There
656 // is already one in the parent class, and we have to round up to avoid
657 // having a zero-element array.
658 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
660 // NumTsAvailable - The number of T's we actually have space for, which may
661 // be more than N due to rounding.
662 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
663 static_cast<unsigned int>(sizeof(T))
665 U InlineElts[NumInlineEltsElts];
667 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
670 explicit SmallVector(unsigned Size, const T &Value = T())
671 : SmallVectorImpl<T>(NumTsAvailable) {
674 this->push_back(Value);
677 template<typename ItTy>
678 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
682 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
684 SmallVectorImpl<T>::operator=(RHS);
687 const SmallVector &operator=(const SmallVector &RHS) {
688 SmallVectorImpl<T>::operator=(RHS);
694 } // End llvm namespace
697 /// Implement std::swap in terms of SmallVector swap.
700 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
704 /// Implement std::swap in terms of SmallVector swap.
705 template<typename T, unsigned N>
707 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {