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 explicit 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 reference operator[](unsigned idx) {
125 assert (Begin + idx < End);
128 const_reference operator[](unsigned idx) const {
129 assert (Begin + idx < End);
136 const_reference front() const {
143 const_reference back() const {
147 void push_back(const_reference Elt) {
148 if (End < Capacity) {
170 destroy_range(Begin, End);
174 void resize(unsigned N) {
176 destroy_range(Begin+N, End);
178 } else if (N > size()) {
179 if (unsigned(Capacity-Begin) < N)
181 construct_range(End, Begin+N, T());
186 void resize(unsigned N, const T &NV) {
188 destroy_range(Begin+N, End);
190 } else if (N > size()) {
191 if (unsigned(Capacity-Begin) < N)
193 construct_range(End, Begin+N, NV);
198 void reserve(unsigned N) {
199 if (unsigned(Capacity-Begin) < N)
203 void swap(SmallVectorImpl &RHS);
205 /// append - Add the specified range to the end of the SmallVector.
207 template<typename in_iter>
208 void append(in_iter in_start, in_iter in_end) {
209 size_type NumInputs = std::distance(in_start, in_end);
210 // Grow allocated space if needed.
211 if (NumInputs > size_type(Capacity-End))
212 grow(size()+NumInputs);
214 // Copy the new elements over.
215 std::uninitialized_copy(in_start, in_end, End);
219 /// append - Add the specified range to the end of the SmallVector.
221 void append(size_type NumInputs, const T &Elt) {
222 // Grow allocated space if needed.
223 if (NumInputs > size_type(Capacity-End))
224 grow(size()+NumInputs);
226 // Copy the new elements over.
227 std::uninitialized_fill_n(End, NumInputs, Elt);
231 void assign(unsigned NumElts, const T &Elt) {
233 if (unsigned(Capacity-Begin) < NumElts)
236 construct_range(Begin, End, Elt);
239 iterator erase(iterator I) {
241 // Shift all elts down one.
242 std::copy(I+1, End, I);
243 // Drop the last elt.
248 iterator erase(iterator S, iterator E) {
250 // Shift all elts down.
251 iterator I = std::copy(E, End, S);
252 // Drop the last elts.
253 destroy_range(I, End);
258 iterator insert(iterator I, const T &Elt) {
259 if (I == End) { // Important special case for empty vector.
264 if (End < Capacity) {
268 // Push everything else over.
269 std::copy_backward(I, End-1, End);
273 size_t EltNo = I-Begin;
279 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
280 if (I == End) { // Important special case for empty vector.
281 append(NumToInsert, Elt);
285 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
286 size_t InsertElt = I-begin();
288 // Ensure there is enough space.
289 reserve(static_cast<unsigned>(size() + NumToInsert));
291 // Uninvalidate the iterator.
292 I = begin()+InsertElt;
294 // If there are more elements between the insertion point and the end of the
295 // range than there are being inserted, we can use a simple approach to
296 // insertion. Since we already reserved space, we know that this won't
297 // reallocate the vector.
298 if (size_t(end()-I) >= NumToInsert) {
300 append(End-NumToInsert, End);
302 // Copy the existing elements that get replaced.
303 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
305 std::fill_n(I, NumToInsert, Elt);
309 // Otherwise, we're inserting more elements than exist already, and we're
310 // not inserting at the end.
312 // Copy over the elements that we're about to overwrite.
315 size_t NumOverwritten = OldEnd-I;
316 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
318 // Replace the overwritten part.
319 std::fill_n(I, NumOverwritten, Elt);
321 // Insert the non-overwritten middle part.
322 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
326 template<typename ItTy>
327 iterator insert(iterator I, ItTy From, ItTy To) {
328 if (I == End) { // Important special case for empty vector.
333 size_t NumToInsert = std::distance(From, To);
334 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
335 size_t InsertElt = I-begin();
337 // Ensure there is enough space.
338 reserve(static_cast<unsigned>(size() + NumToInsert));
340 // Uninvalidate the iterator.
341 I = begin()+InsertElt;
343 // If there are more elements between the insertion point and the end of the
344 // range than there are being inserted, we can use a simple approach to
345 // insertion. Since we already reserved space, we know that this won't
346 // reallocate the vector.
347 if (size_t(end()-I) >= NumToInsert) {
349 append(End-NumToInsert, End);
351 // Copy the existing elements that get replaced.
352 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
354 std::copy(From, To, I);
358 // Otherwise, we're inserting more elements than exist already, and we're
359 // not inserting at the end.
361 // Copy over the elements that we're about to overwrite.
364 size_t NumOverwritten = OldEnd-I;
365 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
367 // Replace the overwritten part.
368 std::copy(From, From+NumOverwritten, I);
370 // Insert the non-overwritten middle part.
371 std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
375 /// data - Return a pointer to the vector's buffer, even if empty().
377 return pointer(Begin);
380 /// data - Return a pointer to the vector's buffer, even if empty().
381 const_pointer data() const {
382 return const_pointer(Begin);
385 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
387 bool operator==(const SmallVectorImpl &RHS) const {
388 if (size() != RHS.size()) return false;
389 for (T *This = Begin, *That = RHS.Begin, *E = Begin+size();
390 This != E; ++This, ++That)
395 bool operator!=(const SmallVectorImpl &RHS) const { return !(*this == RHS); }
397 bool operator<(const SmallVectorImpl &RHS) const {
398 return std::lexicographical_compare(begin(), end(),
399 RHS.begin(), RHS.end());
403 /// isSmall - Return true if this is a smallvector which has not had dynamic
404 /// memory allocated for it.
405 bool isSmall() const {
406 return static_cast<const void*>(Begin) ==
407 static_cast<const void*>(&FirstEl);
410 /// grow - double the size of the allocated memory, guaranteeing space for at
411 /// least one more element or MinSize if specified.
412 void grow(size_type MinSize = 0);
414 void construct_range(T *S, T *E, const T &Elt) {
419 void destroy_range(T *S, T *E) {
427 // Define this out-of-line to dissuade the C++ compiler from inlining it.
428 template <typename T>
429 void SmallVectorImpl<T>::grow(size_t MinSize) {
430 size_t CurCapacity = Capacity-Begin;
431 size_t CurSize = size();
432 size_t NewCapacity = 2*CurCapacity;
433 if (NewCapacity < MinSize)
434 NewCapacity = MinSize;
435 T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T)));
437 // Copy the elements over.
438 if (is_class<T>::value)
439 std::uninitialized_copy(Begin, End, NewElts);
441 // Use memcpy for PODs (std::uninitialized_copy optimizes to memmove).
442 memcpy(NewElts, Begin, CurSize * sizeof(T));
444 // Destroy the original elements.
445 destroy_range(Begin, End);
447 // If this wasn't grown from the inline copy, deallocate the old space.
449 operator delete(Begin);
452 End = NewElts+CurSize;
453 Capacity = Begin+NewCapacity;
456 template <typename T>
457 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
458 if (this == &RHS) return;
460 // We can only avoid copying elements if neither vector is small.
461 if (!isSmall() && !RHS.isSmall()) {
462 std::swap(Begin, RHS.Begin);
463 std::swap(End, RHS.End);
464 std::swap(Capacity, RHS.Capacity);
467 if (RHS.size() > size_type(Capacity-Begin))
469 if (size() > size_type(RHS.Capacity-RHS.begin()))
472 // Swap the shared elements.
473 size_t NumShared = size();
474 if (NumShared > RHS.size()) NumShared = RHS.size();
475 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
476 std::swap(Begin[i], RHS[i]);
478 // Copy over the extra elts.
479 if (size() > RHS.size()) {
480 size_t EltDiff = size() - RHS.size();
481 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
483 destroy_range(Begin+NumShared, End);
484 End = Begin+NumShared;
485 } else if (RHS.size() > size()) {
486 size_t EltDiff = RHS.size() - size();
487 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
489 destroy_range(RHS.Begin+NumShared, RHS.End);
490 RHS.End = RHS.Begin+NumShared;
494 template <typename T>
495 const SmallVectorImpl<T> &
496 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
497 // Avoid self-assignment.
498 if (this == &RHS) return *this;
500 // If we already have sufficient space, assign the common elements, then
501 // destroy any excess.
502 unsigned RHSSize = unsigned(RHS.size());
503 unsigned CurSize = unsigned(size());
504 if (CurSize >= RHSSize) {
505 // Assign common elements.
508 NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
512 // Destroy excess elements.
513 destroy_range(NewEnd, End);
520 // If we have to grow to have enough elements, destroy the current elements.
521 // This allows us to avoid copying them during the grow.
522 if (unsigned(Capacity-Begin) < RHSSize) {
523 // Destroy current elements.
524 destroy_range(Begin, End);
528 } else if (CurSize) {
529 // Otherwise, use assignment for the already-constructed elements.
530 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
533 // Copy construct the new elements in place.
534 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
541 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
542 /// for the case when the array is small. It contains some number of elements
543 /// in-place, which allows it to avoid heap allocation when the actual number of
544 /// elements is below that threshold. This allows normal "small" cases to be
545 /// fast without losing generality for large inputs.
547 /// Note that this does not attempt to be exception safe.
549 template <typename T, unsigned N>
550 class SmallVector : public SmallVectorImpl<T> {
551 /// InlineElts - These are 'N-1' elements that are stored inline in the body
552 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
553 typedef typename SmallVectorImpl<T>::U U;
555 // MinUs - The number of U's require to cover N T's.
556 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
557 static_cast<unsigned int>(sizeof(U)) - 1) /
558 static_cast<unsigned int>(sizeof(U)),
560 // NumInlineEltsElts - The number of elements actually in this array. There
561 // is already one in the parent class, and we have to round up to avoid
562 // having a zero-element array.
563 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
565 // NumTsAvailable - The number of T's we actually have space for, which may
566 // be more than N due to rounding.
567 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
568 static_cast<unsigned int>(sizeof(T))
570 U InlineElts[NumInlineEltsElts];
572 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
575 explicit SmallVector(unsigned Size, const T &Value = T())
576 : SmallVectorImpl<T>(NumTsAvailable) {
579 this->push_back(Value);
582 template<typename ItTy>
583 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
587 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
589 SmallVectorImpl<T>::operator=(RHS);
592 const SmallVector &operator=(const SmallVector &RHS) {
593 SmallVectorImpl<T>::operator=(RHS);
599 } // End llvm namespace
602 /// Implement std::swap in terms of SmallVector swap.
605 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
609 /// Implement std::swap in terms of SmallVector swap.
610 template<typename T, unsigned N>
612 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {