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 {
160 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
161 /// implementations that are designed to work with non-POD-like T's.
162 template <typename T, bool isPodLike>
163 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
165 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
167 static void destroy_range(T *S, T *E) {
174 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
175 /// starting with "Dest", constructing elements into it as needed.
176 template<typename It1, typename It2>
177 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
178 std::uninitialized_copy(I, E, Dest);
183 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
184 /// implementations that are designed to work with POD-like T's.
185 template <typename T>
186 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
188 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
190 // No need to do a destroy loop for POD's.
191 static void destroy_range(T *S, T *E) {}
193 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
194 /// starting with "Dest", constructing elements into it as needed.
195 template<typename It1, typename It2>
196 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
197 // Use memcpy for PODs: std::uninitialized_copy optimizes to memmove, memcpy
199 memcpy(&*Dest, &*I, (E-I)*sizeof(T));
204 /// SmallVectorImpl - This class consists of common code factored out of the
205 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
206 /// template parameter.
207 template <typename T>
208 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
209 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
211 typedef typename SuperClass::iterator iterator;
212 typedef typename SuperClass::size_type size_type;
214 // Default ctor - Initialize to empty.
215 explicit SmallVectorImpl(unsigned N)
216 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
220 // Destroy the constructed elements in the vector.
221 destroy_range(this->begin(), this->end());
223 // If this wasn't grown from the inline copy, deallocate the old space.
224 if (!this->isSmall())
225 operator delete(this->begin());
230 destroy_range(this->begin(), this->end());
231 this->EndX = this->BeginX;
234 void resize(unsigned N) {
235 if (N < this->size()) {
236 this->destroy_range(this->begin()+N, this->end());
237 this->setEnd(this->begin()+N);
238 } else if (N > this->size()) {
239 if (this->capacity() < N)
241 this->construct_range(this->end(), this->begin()+N, T());
242 this->setEnd(this->begin()+N);
246 void resize(unsigned N, const T &NV) {
247 if (N < this->size()) {
248 destroy_range(this->begin()+N, this->end());
249 setEnd(this->begin()+N);
250 } else if (N > this->size()) {
251 if (this->capacity() < N)
253 construct_range(this->end(), this->begin()+N, NV);
254 setEnd(this->begin()+N);
258 void reserve(unsigned N) {
259 if (this->capacity() < N)
263 void push_back(const T &Elt) {
264 if (this->EndX < this->CapacityX) {
266 new (this->end()) T(Elt);
267 setEnd(this->end()+1);
275 setEnd(this->end()-1);
280 T Result = this->back();
286 void swap(SmallVectorImpl &RHS);
288 /// append - Add the specified range to the end of the SmallVector.
290 template<typename in_iter>
291 void append(in_iter in_start, in_iter in_end) {
292 size_type NumInputs = std::distance(in_start, in_end);
293 // Grow allocated space if needed.
294 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
295 grow(this->size()+NumInputs);
297 // Copy the new elements over.
298 // TODO: NEED To compile time dispatch on whether in_iter is a random access
299 // iterator to use the fast uninitialized_copy.
300 std::uninitialized_copy(in_start, in_end, this->end());
301 setEnd(this->end() + NumInputs);
304 /// append - Add the specified range to the end of the SmallVector.
306 void append(size_type NumInputs, const T &Elt) {
307 // Grow allocated space if needed.
308 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
309 grow(this->size()+NumInputs);
311 // Copy the new elements over.
312 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
313 setEnd(this->end() + NumInputs);
316 void assign(unsigned NumElts, const T &Elt) {
318 if (this->capacity() < NumElts)
320 setEnd(this->begin()+NumElts);
321 construct_range(this->begin(), this->end(), Elt);
324 iterator erase(iterator I) {
326 // Shift all elts down one.
327 std::copy(I+1, this->end(), I);
328 // Drop the last elt.
333 iterator erase(iterator S, iterator E) {
335 // Shift all elts down.
336 iterator I = std::copy(E, this->end(), S);
337 // Drop the last elts.
338 destroy_range(I, this->end());
343 iterator insert(iterator I, const T &Elt) {
344 if (I == this->end()) { // Important special case for empty vector.
346 return this->end()-1;
349 if (this->EndX < this->CapacityX) {
351 new (this->end()) T(this->back());
352 this->setEnd(this->end()+1);
353 // Push everything else over.
354 std::copy_backward(I, this->end()-1, this->end());
358 size_t EltNo = I-this->begin();
360 I = this->begin()+EltNo;
364 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
365 if (I == this->end()) { // Important special case for empty vector.
366 append(NumToInsert, Elt);
367 return this->end()-1;
370 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
371 size_t InsertElt = I - this->begin();
373 // Ensure there is enough space.
374 reserve(static_cast<unsigned>(this->size() + NumToInsert));
376 // Uninvalidate the iterator.
377 I = this->begin()+InsertElt;
379 // If there are more elements between the insertion point and the end of the
380 // range than there are being inserted, we can use a simple approach to
381 // insertion. Since we already reserved space, we know that this won't
382 // reallocate the vector.
383 if (size_t(this->end()-I) >= NumToInsert) {
384 T *OldEnd = this->end();
385 append(this->end()-NumToInsert, this->end());
387 // Copy the existing elements that get replaced.
388 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
390 std::fill_n(I, NumToInsert, Elt);
394 // Otherwise, we're inserting more elements than exist already, and we're
395 // not inserting at the end.
397 // Copy over the elements that we're about to overwrite.
398 T *OldEnd = this->end();
399 setEnd(this->end() + NumToInsert);
400 size_t NumOverwritten = OldEnd-I;
401 uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
403 // Replace the overwritten part.
404 std::fill_n(I, NumOverwritten, Elt);
406 // Insert the non-overwritten middle part.
407 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
411 template<typename ItTy>
412 iterator insert(iterator I, ItTy From, ItTy To) {
413 if (I == this->end()) { // Important special case for empty vector.
415 return this->end()-1;
418 size_t NumToInsert = std::distance(From, To);
419 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
420 size_t InsertElt = I - this->begin();
422 // Ensure there is enough space.
423 reserve(static_cast<unsigned>(this->size() + NumToInsert));
425 // Uninvalidate the iterator.
426 I = this->begin()+InsertElt;
428 // If there are more elements between the insertion point and the end of the
429 // range than there are being inserted, we can use a simple approach to
430 // insertion. Since we already reserved space, we know that this won't
431 // reallocate the vector.
432 if (size_t(this->end()-I) >= NumToInsert) {
433 T *OldEnd = this->end();
434 append(this->end()-NumToInsert, this->end());
436 // Copy the existing elements that get replaced.
437 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
439 std::copy(From, To, I);
443 // Otherwise, we're inserting more elements than exist already, and we're
444 // not inserting at the end.
446 // Copy over the elements that we're about to overwrite.
447 T *OldEnd = this->end();
448 setEnd(this->end() + NumToInsert);
449 size_t NumOverwritten = OldEnd-I;
450 uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
452 // Replace the overwritten part.
453 std::copy(From, From+NumOverwritten, I);
455 // Insert the non-overwritten middle part.
456 uninitialized_copy(From+NumOverwritten, To, OldEnd);
460 const SmallVectorImpl
461 &operator=(const SmallVectorImpl &RHS);
463 bool operator==(const SmallVectorImpl &RHS) const {
464 if (this->size() != RHS.size()) return false;
465 return std::equal(this->begin(), this->end(), RHS.begin());
467 bool operator!=(const SmallVectorImpl &RHS) const {
468 return !(*this == RHS);
471 bool operator<(const SmallVectorImpl &RHS) const {
472 return std::lexicographical_compare(this->begin(), this->end(),
473 RHS.begin(), RHS.end());
476 /// set_size - Set the array size to \arg N, which the current array must have
477 /// enough capacity for.
479 /// This does not construct or destroy any elements in the vector.
481 /// Clients can use this in conjunction with capacity() to write past the end
482 /// of the buffer when they know that more elements are available, and only
483 /// update the size later. This avoids the cost of value initializing elements
484 /// which will only be overwritten.
485 void set_size(unsigned N) {
486 assert(N <= this->capacity());
487 setEnd(this->begin() + N);
491 /// grow - double the size of the allocated memory, guaranteeing space for at
492 /// least one more element or MinSize if specified.
493 void grow(size_t MinSize = 0);
495 static void construct_range(T *S, T *E, const T &Elt) {
502 // Define this out-of-line to dissuade the C++ compiler from inlining it.
503 template <typename T>
504 void SmallVectorImpl<T>::grow(size_t MinSize) {
505 size_t CurCapacity = this->capacity();
506 size_t CurSize = this->size();
507 size_t NewCapacity = 2*CurCapacity;
508 if (NewCapacity < MinSize)
509 NewCapacity = MinSize;
510 T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T)));
512 // Copy the elements over.
513 uninitialized_copy(this->begin(), this->end(), NewElts);
515 // Destroy the original elements.
516 destroy_range(this->begin(), this->end());
518 // If this wasn't grown from the inline copy, deallocate the old space.
519 if (!this->isSmall())
520 operator delete(this->begin());
522 setEnd(NewElts+CurSize);
523 this->BeginX = NewElts;
524 this->CapacityX = this->begin()+NewCapacity;
527 template <typename T>
528 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
529 if (this == &RHS) return;
531 // We can only avoid copying elements if neither vector is small.
532 if (!this->isSmall() && !RHS.isSmall()) {
533 std::swap(this->BeginX, RHS.BeginX);
534 std::swap(this->EndX, RHS.EndX);
535 std::swap(this->CapacityX, RHS.CapacityX);
538 if (RHS.size() > this->capacity())
540 if (this->size() > RHS.capacity())
541 RHS.grow(this->size());
543 // Swap the shared elements.
544 size_t NumShared = this->size();
545 if (NumShared > RHS.size()) NumShared = RHS.size();
546 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
547 std::swap((*this)[i], RHS[i]);
549 // Copy over the extra elts.
550 if (this->size() > RHS.size()) {
551 size_t EltDiff = this->size() - RHS.size();
552 uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
553 RHS.setEnd(RHS.end()+EltDiff);
554 destroy_range(this->begin()+NumShared, this->end());
555 setEnd(this->begin()+NumShared);
556 } else if (RHS.size() > this->size()) {
557 size_t EltDiff = RHS.size() - this->size();
558 uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
559 setEnd(this->end() + EltDiff);
560 destroy_range(RHS.begin()+NumShared, RHS.end());
561 RHS.setEnd(RHS.begin()+NumShared);
565 template <typename T>
566 const SmallVectorImpl<T> &SmallVectorImpl<T>::
567 operator=(const SmallVectorImpl<T> &RHS) {
568 // Avoid self-assignment.
569 if (this == &RHS) return *this;
571 // If we already have sufficient space, assign the common elements, then
572 // destroy any excess.
573 size_t RHSSize = RHS.size();
574 size_t CurSize = this->size();
575 if (CurSize >= RHSSize) {
576 // Assign common elements.
579 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
581 NewEnd = this->begin();
583 // Destroy excess elements.
584 destroy_range(NewEnd, this->end());
591 // If we have to grow to have enough elements, destroy the current elements.
592 // This allows us to avoid copying them during the grow.
593 if (this->capacity() < RHSSize) {
594 // Destroy current elements.
595 destroy_range(this->begin(), this->end());
596 setEnd(this->begin());
599 } else if (CurSize) {
600 // Otherwise, use assignment for the already-constructed elements.
601 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
604 // Copy construct the new elements in place.
605 uninitialized_copy(RHS.begin()+CurSize, RHS.end(), this->begin()+CurSize);
608 setEnd(this->begin()+RHSSize);
613 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
614 /// for the case when the array is small. It contains some number of elements
615 /// in-place, which allows it to avoid heap allocation when the actual number of
616 /// elements is below that threshold. This allows normal "small" cases to be
617 /// fast without losing generality for large inputs.
619 /// Note that this does not attempt to be exception safe.
621 template <typename T, unsigned N>
622 class SmallVector : public SmallVectorImpl<T> {
623 /// InlineElts - These are 'N-1' elements that are stored inline in the body
624 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
625 typedef typename SmallVectorImpl<T>::U U;
627 // MinUs - The number of U's require to cover N T's.
628 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
629 static_cast<unsigned int>(sizeof(U)) - 1) /
630 static_cast<unsigned int>(sizeof(U)),
632 // NumInlineEltsElts - The number of elements actually in this array. There
633 // is already one in the parent class, and we have to round up to avoid
634 // having a zero-element array.
635 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
637 // NumTsAvailable - The number of T's we actually have space for, which may
638 // be more than N due to rounding.
639 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
640 static_cast<unsigned int>(sizeof(T))
642 U InlineElts[NumInlineEltsElts];
644 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
647 explicit SmallVector(unsigned Size, const T &Value = T())
648 : SmallVectorImpl<T>(NumTsAvailable) {
651 this->push_back(Value);
654 template<typename ItTy>
655 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
659 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
661 SmallVectorImpl<T>::operator=(RHS);
664 const SmallVector &operator=(const SmallVector &RHS) {
665 SmallVectorImpl<T>::operator=(RHS);
671 } // End llvm namespace
674 /// Implement std::swap in terms of SmallVector swap.
677 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
681 /// Implement std::swap in terms of SmallVector swap.
682 template<typename T, unsigned N>
684 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {