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/ADT/iterator.h"
18 #include "llvm/Support/type_traits.h"
27 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
28 // additional overloads so that elements with pointer types are recognized as
29 // scalars and not objects, causing bizarre type conversion errors.
30 template<class T1, class T2>
31 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
32 _Scalar_ptr_iterator_tag _Cat;
36 template<class T1, class T2>
37 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
38 _Scalar_ptr_iterator_tag _Cat;
42 // FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
43 // is that the above hack won't work if it wasn't fixed.
50 /// SmallVectorImpl - This class consists of common code factored out of the
51 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
52 /// template parameter.
54 class SmallVectorImpl {
56 T *Begin, *End, *Capacity;
58 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
59 // don't want it to be automatically run, so we need to represent the space as
60 // something else. An array of char would work great, but might not be
61 // aligned sufficiently. Instead, we either use GCC extensions, or some
62 // number of union instances for the space, which guarantee maximal alignment.
66 U FirstEl __attribute__((aligned));
75 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
77 // Default ctor - Initialize to empty.
78 SmallVectorImpl(unsigned N)
79 : Begin(reinterpret_cast<T*>(&FirstEl)),
80 End(reinterpret_cast<T*>(&FirstEl)),
81 Capacity(reinterpret_cast<T*>(&FirstEl)+N) {
85 // Destroy the constructed elements in the vector.
86 destroy_range(Begin, End);
88 // If this wasn't grown from the inline copy, deallocate the old space.
90 operator delete(Begin);
93 typedef size_t size_type;
94 typedef ptrdiff_t difference_type;
97 typedef const T* const_iterator;
99 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
100 typedef std::reverse_iterator<iterator> reverse_iterator;
102 typedef T& reference;
103 typedef const T& const_reference;
105 typedef const T* const_pointer;
107 bool empty() const { return Begin == End; }
108 size_type size() const { return End-Begin; }
109 size_type max_size() const { return size_type(-1) / sizeof(T); }
111 // forward iterator creation methods.
112 iterator begin() { return Begin; }
113 const_iterator begin() const { return Begin; }
114 iterator end() { return End; }
115 const_iterator end() const { return End; }
117 // reverse iterator creation methods.
118 reverse_iterator rbegin() { return reverse_iterator(end()); }
119 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
120 reverse_iterator rend() { return reverse_iterator(begin()); }
121 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
124 /* These asserts could be "Begin + idx < End", but there are lots of places
125 in llvm where we use &v[v.size()] instead of v.end(). */
126 reference operator[](unsigned idx) {
127 assert (Begin + idx <= End);
130 const_reference operator[](unsigned idx) const {
131 assert (Begin + idx <= End);
138 const_reference front() const {
145 const_reference back() const {
149 void push_back(const_reference Elt) {
150 if (End < Capacity) {
166 destroy_range(Begin, End);
170 void resize(unsigned N) {
172 destroy_range(Begin+N, End);
174 } else if (N > size()) {
175 if (unsigned(Capacity-Begin) < N)
177 construct_range(End, Begin+N, T());
182 void resize(unsigned N, const T &NV) {
184 destroy_range(Begin+N, End);
186 } else if (N > size()) {
187 if (unsigned(Capacity-Begin) < N)
189 construct_range(End, Begin+N, NV);
194 void reserve(unsigned N) {
195 if (unsigned(Capacity-Begin) < N)
199 void swap(SmallVectorImpl &RHS);
201 /// append - Add the specified range to the end of the SmallVector.
203 template<typename in_iter>
204 void append(in_iter in_start, in_iter in_end) {
205 size_type NumInputs = std::distance(in_start, in_end);
206 // Grow allocated space if needed.
207 if (End+NumInputs > Capacity)
208 grow(size()+NumInputs);
210 // Copy the new elements over.
211 std::uninitialized_copy(in_start, in_end, End);
215 /// append - Add the specified range to the end of the SmallVector.
217 void append(size_type NumInputs, const T &Elt) {
218 // Grow allocated space if needed.
219 if (End+NumInputs > Capacity)
220 grow(size()+NumInputs);
222 // Copy the new elements over.
223 std::uninitialized_fill_n(End, NumInputs, Elt);
227 void assign(unsigned NumElts, const T &Elt) {
229 if (unsigned(Capacity-Begin) < NumElts)
232 construct_range(Begin, End, Elt);
235 iterator erase(iterator I) {
237 // Shift all elts down one.
238 std::copy(I+1, End, I);
239 // Drop the last elt.
244 iterator erase(iterator S, iterator E) {
246 // Shift all elts down.
247 iterator I = std::copy(E, End, S);
248 // Drop the last elts.
249 destroy_range(I, End);
254 iterator insert(iterator I, const T &Elt) {
255 if (I == End) { // Important special case for empty vector.
260 if (End < Capacity) {
264 // Push everything else over.
265 std::copy_backward(I, End-1, End);
269 size_t EltNo = I-Begin;
275 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
276 if (I == End) { // Important special case for empty vector.
277 append(NumToInsert, Elt);
281 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
282 size_t InsertElt = I-begin();
284 // Ensure there is enough space.
285 reserve(static_cast<unsigned>(size() + NumToInsert));
287 // Uninvalidate the iterator.
288 I = begin()+InsertElt;
290 // If we already have this many elements in the collection, append the
291 // dest elements at the end, then copy over the appropriate elements. Since
292 // we already reserved space, we know that this won't reallocate the vector.
293 if (size() >= NumToInsert) {
295 append(End-NumToInsert, End);
297 // Copy the existing elements that get replaced.
298 std::copy(I, OldEnd-NumToInsert, I+NumToInsert);
300 std::fill_n(I, NumToInsert, Elt);
304 // Otherwise, we're inserting more elements than exist already, and we're
305 // not inserting at the end.
307 // Copy over the elements that we're about to overwrite.
310 size_t NumOverwritten = OldEnd-I;
311 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
313 // Replace the overwritten part.
314 std::fill_n(I, NumOverwritten, Elt);
316 // Insert the non-overwritten middle part.
317 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
321 template<typename ItTy>
322 iterator insert(iterator I, ItTy From, ItTy To) {
323 if (I == End) { // Important special case for empty vector.
328 size_t NumToInsert = std::distance(From, To);
329 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
330 size_t InsertElt = I-begin();
332 // Ensure there is enough space.
333 reserve(static_cast<unsigned>(size() + NumToInsert));
335 // Uninvalidate the iterator.
336 I = begin()+InsertElt;
338 // If we already have this many elements in the collection, append the
339 // dest elements at the end, then copy over the appropriate elements. Since
340 // we already reserved space, we know that this won't reallocate the vector.
341 if (size() >= NumToInsert) {
343 append(End-NumToInsert, End);
345 // Copy the existing elements that get replaced.
346 std::copy(I, OldEnd-NumToInsert, I+NumToInsert);
348 std::copy(From, To, I);
352 // Otherwise, we're inserting more elements than exist already, and we're
353 // not inserting at the end.
355 // Copy over the elements that we're about to overwrite.
358 size_t NumOverwritten = OldEnd-I;
359 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
361 // Replace the overwritten part.
362 std::copy(From, From+NumOverwritten, I);
364 // Insert the non-overwritten middle part.
365 std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
369 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
371 bool operator==(const SmallVectorImpl &RHS) const {
372 if (size() != RHS.size()) return false;
373 for (T *This = Begin, *That = RHS.Begin, *E = Begin+size();
374 This != E; ++This, ++That)
379 bool operator!=(const SmallVectorImpl &RHS) const { return !(*this == RHS); }
381 bool operator<(const SmallVectorImpl &RHS) const {
382 return std::lexicographical_compare(begin(), end(),
383 RHS.begin(), RHS.end());
387 /// isSmall - Return true if this is a smallvector which has not had dynamic
388 /// memory allocated for it.
389 bool isSmall() const {
390 return static_cast<const void*>(Begin) ==
391 static_cast<const void*>(&FirstEl);
394 /// grow - double the size of the allocated memory, guaranteeing space for at
395 /// least one more element or MinSize if specified.
396 void grow(size_type MinSize = 0);
398 void construct_range(T *S, T *E, const T &Elt) {
403 void destroy_range(T *S, T *E) {
411 // Define this out-of-line to dissuade the C++ compiler from inlining it.
412 template <typename T>
413 void SmallVectorImpl<T>::grow(size_t MinSize) {
414 size_t CurCapacity = Capacity-Begin;
415 size_t CurSize = size();
416 size_t NewCapacity = 2*CurCapacity;
417 if (NewCapacity < MinSize)
418 NewCapacity = MinSize;
419 T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T)));
421 // Copy the elements over.
422 if (is_class<T>::value)
423 std::uninitialized_copy(Begin, End, NewElts);
425 // Use memcpy for PODs (std::uninitialized_copy optimizes to memmove).
426 memcpy(NewElts, Begin, CurSize * sizeof(T));
428 // Destroy the original elements.
429 destroy_range(Begin, End);
431 // If this wasn't grown from the inline copy, deallocate the old space.
433 operator delete(Begin);
436 End = NewElts+CurSize;
437 Capacity = Begin+NewCapacity;
440 template <typename T>
441 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
442 if (this == &RHS) return;
444 // We can only avoid copying elements if neither vector is small.
445 if (!isSmall() && !RHS.isSmall()) {
446 std::swap(Begin, RHS.Begin);
447 std::swap(End, RHS.End);
448 std::swap(Capacity, RHS.Capacity);
451 if (Begin+RHS.size() > Capacity)
453 if (RHS.begin()+size() > RHS.Capacity)
456 // Swap the shared elements.
457 size_t NumShared = size();
458 if (NumShared > RHS.size()) NumShared = RHS.size();
459 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
460 std::swap(Begin[i], RHS[i]);
462 // Copy over the extra elts.
463 if (size() > RHS.size()) {
464 size_t EltDiff = size() - RHS.size();
465 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
467 destroy_range(Begin+NumShared, End);
468 End = Begin+NumShared;
469 } else if (RHS.size() > size()) {
470 size_t EltDiff = RHS.size() - size();
471 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
473 destroy_range(RHS.Begin+NumShared, RHS.End);
474 RHS.End = RHS.Begin+NumShared;
478 template <typename T>
479 const SmallVectorImpl<T> &
480 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
481 // Avoid self-assignment.
482 if (this == &RHS) return *this;
484 // If we already have sufficient space, assign the common elements, then
485 // destroy any excess.
486 unsigned RHSSize = unsigned(RHS.size());
487 unsigned CurSize = unsigned(size());
488 if (CurSize >= RHSSize) {
489 // Assign common elements.
492 NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
496 // Destroy excess elements.
497 destroy_range(NewEnd, End);
504 // If we have to grow to have enough elements, destroy the current elements.
505 // This allows us to avoid copying them during the grow.
506 if (unsigned(Capacity-Begin) < RHSSize) {
507 // Destroy current elements.
508 destroy_range(Begin, End);
512 } else if (CurSize) {
513 // Otherwise, use assignment for the already-constructed elements.
514 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
517 // Copy construct the new elements in place.
518 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
525 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
526 /// for the case when the array is small. It contains some number of elements
527 /// in-place, which allows it to avoid heap allocation when the actual number of
528 /// elements is below that threshold. This allows normal "small" cases to be
529 /// fast without losing generality for large inputs.
531 /// Note that this does not attempt to be exception safe.
533 template <typename T, unsigned N>
534 class SmallVector : public SmallVectorImpl<T> {
535 /// InlineElts - These are 'N-1' elements that are stored inline in the body
536 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
537 typedef typename SmallVectorImpl<T>::U U;
539 // MinUs - The number of U's require to cover N T's.
540 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
541 static_cast<unsigned int>(sizeof(U)) - 1) /
542 static_cast<unsigned int>(sizeof(U)),
544 // NumInlineEltsElts - The number of elements actually in this array. There
545 // is already one in the parent class, and we have to round up to avoid
546 // having a zero-element array.
547 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
549 // NumTsAvailable - The number of T's we actually have space for, which may
550 // be more than N due to rounding.
551 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
552 static_cast<unsigned int>(sizeof(T))
554 U InlineElts[NumInlineEltsElts];
556 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
559 explicit SmallVector(unsigned Size, const T &Value = T())
560 : SmallVectorImpl<T>(NumTsAvailable) {
566 template<typename ItTy>
567 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
571 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
576 const SmallVector &operator=(const SmallVector &RHS) {
577 SmallVectorImpl<T>::operator=(RHS);
583 } // End llvm namespace
586 /// Implement std::swap in terms of SmallVector swap.
589 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
593 /// Implement std::swap in terms of SmallVector swap.
594 template<typename T, unsigned N>
596 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {