1 //===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Chris Lattner and is distributed under
6 // the University of Illinois Open Source 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
23 // Fix bug in VC++ implementation of std::uninitialized_copy. Define
24 // additional overloads so that the copy is recognized as a scalar and
25 // not an object copy.
26 template<class T1, class T2>
27 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
28 _Scalar_ptr_iterator_tag _Cat;
32 template<class T1, class T2>
33 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
34 _Scalar_ptr_iterator_tag _Cat;
42 /// SmallVectorImpl - This class consists of common code factored out of the
43 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
44 /// template parameter.
46 class SmallVectorImpl {
48 T *Begin, *End, *Capacity;
50 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
51 // don't want it to be automatically run, so we need to represent the space as
52 // something else. An array of char would work great, but might not be
53 // aligned sufficiently. Instead, we either use GCC extensions, or some
54 // number of union instances for the space, which guarantee maximal alignment.
58 U FirstEl __attribute__((aligned));
67 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
69 // Default ctor - Initialize to empty.
70 SmallVectorImpl(unsigned N)
71 : Begin((T*)&FirstEl), End((T*)&FirstEl), Capacity((T*)&FirstEl+N) {
75 // Destroy the constructed elements in the vector.
76 destroy_range(Begin, End);
78 // If this wasn't grown from the inline copy, deallocate the old space.
80 delete[] (char*)Begin;
83 typedef size_t size_type;
85 typedef const T* const_iterator;
87 typedef const T& const_reference;
89 bool empty() const { return Begin == End; }
90 size_type size() const { return End-Begin; }
92 iterator begin() { return Begin; }
93 const_iterator begin() const { return Begin; }
95 iterator end() { return End; }
96 const_iterator end() const { return End; }
98 reference operator[](unsigned idx) {
101 const_reference operator[](unsigned idx) const {
108 const_reference front() const {
115 const_reference back() const {
119 void push_back(const_reference Elt) {
120 if (End < Capacity) {
136 destroy_range(Begin, End);
140 void resize(unsigned N) {
142 destroy_range(Begin+N, End);
144 } else if (N > size()) {
145 if (Begin+N > Capacity)
147 construct_range(End, Begin+N, T());
152 void resize(unsigned N, const T &NV) {
154 destroy_range(Begin+N, End);
156 } else if (N > size()) {
157 if (Begin+N > Capacity)
159 construct_range(End, Begin+N, NV);
164 void reserve(unsigned N) {
165 if (unsigned(Capacity-Begin) < N)
169 void swap(SmallVectorImpl &RHS);
171 /// append - Add the specified range to the end of the SmallVector.
173 template<typename in_iter>
174 void append(in_iter in_start, in_iter in_end) {
175 unsigned NumInputs = std::distance(in_start, in_end);
176 // Grow allocated space if needed.
177 if (End+NumInputs > Capacity)
178 grow(size()+NumInputs);
180 // Copy the new elements over.
181 std::uninitialized_copy(in_start, in_end, End);
185 void assign(unsigned NumElts, const T &Elt) {
187 if (Begin+NumElts > Capacity)
190 construct_range(Begin, End, Elt);
193 void erase(iterator I) {
194 // Shift all elts down one.
195 std::copy(I+1, End, I);
196 // Drop the last elt.
200 void erase(iterator S, iterator E) {
201 // Shift all elts down.
202 iterator I = std::copy(E, End, S);
203 // Drop the last elts.
204 destroy_range(I, End);
208 iterator insert(iterator I, const T &Elt) {
209 if (I == End) { // Important special case for empty vector.
214 if (End < Capacity) {
218 // Push everything else over.
219 std::copy_backward(I, End-1, End);
223 unsigned EltNo = I-Begin;
229 template<typename ItTy>
230 iterator insert(iterator I, ItTy From, ItTy To) {
231 if (I == End) { // Important special case for empty vector.
236 unsigned NumToInsert = std::distance(From, To);
237 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
238 unsigned InsertElt = I-begin();
240 // Ensure there is enough space.
241 reserve(size() + NumToInsert);
243 // Uninvalidate the iterator.
244 I = begin()+InsertElt;
246 // If we already have this many elements in the collection, append the
247 // dest elements at the end, then copy over the appropriate elements. Since
248 // we already reserved space, we know that this won't reallocate the vector.
249 if (size() >= NumToInsert) {
251 append(End-NumToInsert, End);
253 // Copy the existing elements that get replaced.
254 std::copy(I, OldEnd-NumToInsert, I+NumToInsert);
256 std::copy(From, To, I);
260 // Otherwise, we're inserting more elements than exist already, and we're
261 // not inserting at the end.
263 // Copy over the elements that we're about to overwrite.
266 unsigned NumOverwritten = OldEnd-I;
267 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
269 // Replace the overwritten part.
270 std::copy(From, From+NumOverwritten, I);
272 // Insert the non-overwritten middle part.
273 std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
277 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
280 /// isSmall - Return true if this is a smallvector which has not had dynamic
281 /// memory allocated for it.
282 bool isSmall() const {
283 return (void*)Begin == (void*)&FirstEl;
286 /// grow - double the size of the allocated memory, guaranteeing space for at
287 /// least one more element or MinSize if specified.
288 void grow(unsigned MinSize = 0);
290 void construct_range(T *S, T *E, const T &Elt) {
295 void destroy_range(T *S, T *E) {
303 // Define this out-of-line to dissuade the C++ compiler from inlining it.
304 template <typename T>
305 void SmallVectorImpl<T>::grow(unsigned MinSize) {
306 unsigned CurCapacity = Capacity-Begin;
307 unsigned CurSize = size();
308 unsigned NewCapacity = 2*CurCapacity;
309 if (NewCapacity < MinSize)
310 NewCapacity = MinSize;
311 T *NewElts = reinterpret_cast<T*>(new char[NewCapacity*sizeof(T)]);
313 // Copy the elements over.
314 std::uninitialized_copy(Begin, End, NewElts);
316 // Destroy the original elements.
317 destroy_range(Begin, End);
319 // If this wasn't grown from the inline copy, deallocate the old space.
321 delete[] (char*)Begin;
324 End = NewElts+CurSize;
325 Capacity = Begin+NewCapacity;
328 template <typename T>
329 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
330 if (this == &RHS) return;
332 // We can only avoid copying elements if neither vector is small.
333 if (!isSmall() && !RHS.isSmall()) {
334 std::swap(Begin, RHS.Begin);
335 std::swap(End, RHS.End);
336 std::swap(Capacity, RHS.Capacity);
339 if (Begin+RHS.size() > Capacity)
341 if (RHS.begin()+size() > RHS.Capacity)
344 // Swap the shared elements.
345 unsigned NumShared = size();
346 if (NumShared > RHS.size()) NumShared = RHS.size();
347 for (unsigned i = 0; i != NumShared; ++i)
348 std::swap(Begin[i], RHS[i]);
350 // Copy over the extra elts.
351 if (size() > RHS.size()) {
352 unsigned EltDiff = size() - RHS.size();
353 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
355 destroy_range(Begin+NumShared, End);
356 End = Begin+NumShared;
357 } else if (RHS.size() > size()) {
358 unsigned EltDiff = RHS.size() - size();
359 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
361 destroy_range(RHS.Begin+NumShared, RHS.End);
362 RHS.End = RHS.Begin+NumShared;
366 template <typename T>
367 const SmallVectorImpl<T> &
368 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
369 // Avoid self-assignment.
370 if (this == &RHS) return *this;
372 // If we already have sufficient space, assign the common elements, then
373 // destroy any excess.
374 unsigned RHSSize = RHS.size();
375 unsigned CurSize = size();
376 if (CurSize >= RHSSize) {
377 // Assign common elements.
378 iterator NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
380 // Destroy excess elements.
381 destroy_range(NewEnd, End);
388 // If we have to grow to have enough elements, destroy the current elements.
389 // This allows us to avoid copying them during the grow.
390 if (unsigned(Capacity-Begin) < RHSSize) {
391 // Destroy current elements.
392 destroy_range(Begin, End);
396 } else if (CurSize) {
397 // Otherwise, use assignment for the already-constructed elements.
398 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
401 // Copy construct the new elements in place.
402 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
409 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
410 /// for the case when the array is small. It contains some number of elements
411 /// in-place, which allows it to avoid heap allocation when the actual number of
412 /// elements is below that threshold. This allows normal "small" cases to be
413 /// fast without losing generality for large inputs.
415 /// Note that this does not attempt to be exception safe.
417 template <typename T, unsigned N>
418 class SmallVector : public SmallVectorImpl<T> {
419 /// InlineElts - These are 'N-1' elements that are stored inline in the body
420 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
421 typedef typename SmallVectorImpl<T>::U U;
423 // MinUs - The number of U's require to cover N T's.
424 MinUs = (sizeof(T)*N+sizeof(U)-1)/sizeof(U),
426 // NumInlineEltsElts - The number of elements actually in this array. There
427 // is already one in the parent class, and we have to round up to avoid
428 // having a zero-element array.
429 NumInlineEltsElts = (MinUs - 1) > 0 ? (MinUs - 1) : 1,
431 // NumTsAvailable - The number of T's we actually have space for, which may
432 // be more than N due to rounding.
433 NumTsAvailable = (NumInlineEltsElts+1)*sizeof(U) / sizeof(T)
435 U InlineElts[NumInlineEltsElts];
437 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
440 SmallVector(unsigned Size, const T &Value)
441 : SmallVectorImpl<T>(NumTsAvailable) {
447 template<typename ItTy>
448 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
452 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
456 const SmallVector &operator=(const SmallVector &RHS) {
457 SmallVectorImpl<T>::operator=(RHS);
462 } // End llvm namespace
465 /// Implement std::swap in terms of SmallVector swap.
468 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
472 /// Implement std::swap in terms of SmallVector swap.
473 template<typename T, unsigned N>
475 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {