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 /// SmallVectorImpl - This class consists of common code factored out of the
24 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
25 /// template parameter.
27 class SmallVectorImpl {
28 T *Begin, *End, *Capacity;
30 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
31 // don't want it to be automatically run, so we need to represent the space as
32 // something else. An array of char would work great, but might not be
33 // aligned sufficiently. Instead, we either use GCC extensions, or some
34 // number of union instances for the space, which guarantee maximal alignment.
38 U FirstEl __attribute__((aligned(__alignof__(double))));
47 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
49 // Default ctor - Initialize to empty.
50 SmallVectorImpl(unsigned N)
51 : Begin((T*)&FirstEl), End((T*)&FirstEl), Capacity((T*)&FirstEl+N) {
55 // Destroy the constructed elements in the vector.
56 destroy_range(Begin, End);
58 // If this wasn't grown from the inline copy, deallocate the old space.
60 delete[] (char*)Begin;
63 typedef size_t size_type;
65 typedef const T* const_iterator;
67 typedef const T& const_reference;
69 bool empty() const { return Begin == End; }
70 size_type size() const { return End-Begin; }
72 iterator begin() { return Begin; }
73 const_iterator begin() const { return Begin; }
75 iterator end() { return End; }
76 const_iterator end() const { return End; }
78 reference operator[](unsigned idx) {
81 const_reference operator[](unsigned idx) const {
88 const_reference front() const {
95 const_reference back() const {
99 void push_back(const_reference Elt) {
100 if (End < Capacity) {
116 destroy_range(Begin, End);
120 void resize(unsigned N) {
122 destroy_range(Begin+N, End);
124 } else if (N > size()) {
125 if (Begin+N > Capacity)
127 construct_range(End, Begin+N, T());
132 void resize(unsigned N, const T &NV) {
134 destroy_range(Begin+N, End);
136 } else if (N > size()) {
137 if (Begin+N > Capacity)
139 construct_range(End, Begin+N, NV);
144 void reserve(unsigned N) {
145 if (unsigned(Capacity-Begin) < N)
149 void swap(SmallVectorImpl &RHS);
151 /// append - Add the specified range to the end of the SmallVector.
153 template<typename in_iter>
154 void append(in_iter in_start, in_iter in_end) {
155 unsigned NumInputs = std::distance(in_start, in_end);
156 // Grow allocated space if needed.
157 if (End+NumInputs > Capacity)
158 grow(size()+NumInputs);
160 // Copy the new elements over.
161 std::uninitialized_copy(in_start, in_end, End);
165 void assign(unsigned NumElts, const T &Elt) {
167 if (Begin+NumElts > Capacity)
170 construct_range(Begin, End, Elt);
173 void erase(iterator I) {
174 // Shift all elts down one.
175 std::copy(I+1, End, I);
176 // Drop the last elt.
180 void erase(iterator S, iterator E) {
181 // Shift all elts down.
182 iterator I = std::copy(E, End, S);
183 // Drop the last elts.
184 destroy_range(I, End);
188 iterator insert(iterator I, const T &Elt) {
189 if (I == End) { // Important special case for empty vector.
194 if (End < Capacity) {
198 // Push everything else over.
199 std::copy_backward(I, End-1, End);
203 unsigned EltNo = I-Begin;
209 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
212 /// isSmall - Return true if this is a smallvector which has not had dynamic
213 /// memory allocated for it.
214 bool isSmall() const {
215 return (void*)Begin == (void*)&FirstEl;
218 /// grow - double the size of the allocated memory, guaranteeing space for at
219 /// least one more element or MinSize if specified.
220 void grow(unsigned MinSize = 0);
222 void construct_range(T *S, T *E, const T &Elt) {
228 void destroy_range(T *S, T *E) {
236 // Define this out-of-line to dissuade the C++ compiler from inlining it.
237 template <typename T>
238 void SmallVectorImpl<T>::grow(unsigned MinSize) {
239 unsigned CurCapacity = Capacity-Begin;
240 unsigned CurSize = size();
241 unsigned NewCapacity = 2*CurCapacity;
242 if (NewCapacity < MinSize)
243 NewCapacity = MinSize;
244 T *NewElts = reinterpret_cast<T*>(new char[NewCapacity*sizeof(T)]);
246 // Copy the elements over.
247 std::uninitialized_copy(Begin, End, NewElts);
249 // Destroy the original elements.
250 destroy_range(Begin, End);
252 // If this wasn't grown from the inline copy, deallocate the old space.
254 delete[] (char*)Begin;
257 End = NewElts+CurSize;
258 Capacity = Begin+NewCapacity;
261 template <typename T>
262 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
263 if (this == &RHS) return;
265 // We can only avoid copying elements if neither vector is small.
266 if (!isSmall() && !RHS.isSmall()) {
267 std::swap(Begin, RHS.Begin);
268 std::swap(End, RHS.End);
269 std::swap(Capacity, RHS.Capacity);
272 if (Begin+RHS.size() > Capacity)
274 if (RHS.begin()+size() > RHS.Capacity)
277 // Swap the shared elements.
278 unsigned NumShared = size();
279 if (NumShared > RHS.size()) NumShared = RHS.size();
280 for (unsigned i = 0; i != NumShared; ++i)
281 std::swap(Begin[i], RHS[i]);
283 // Copy over the extra elts.
284 if (size() > RHS.size()) {
285 unsigned EltDiff = size() - RHS.size();
286 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
288 destroy_range(Begin+NumShared, End);
289 End = Begin+NumShared;
290 } else if (RHS.size() > size()) {
291 unsigned EltDiff = RHS.size() - size();
292 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
294 destroy_range(RHS.Begin+NumShared, RHS.End);
295 RHS.End = RHS.Begin+NumShared;
299 template <typename T>
300 const SmallVectorImpl<T> &
301 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
302 // Avoid self-assignment.
303 if (this == &RHS) return *this;
305 // If we already have sufficient space, assign the common elements, then
306 // destroy any excess.
307 unsigned RHSSize = RHS.size();
308 unsigned CurSize = size();
309 if (CurSize >= RHSSize) {
310 // Assign common elements.
311 iterator NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
313 // Destroy excess elements.
314 destroy_range(NewEnd, End);
321 // If we have to grow to have enough elements, destroy the current elements.
322 // This allows us to avoid copying them during the grow.
323 if (unsigned(Capacity-Begin) < RHSSize) {
324 // Destroy current elements.
325 destroy_range(Begin, End);
329 } else if (CurSize) {
330 // Otherwise, use assignment for the already-constructed elements.
331 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
334 // Copy construct the new elements in place.
335 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
342 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
343 /// for the case when the array is small. It contains some number of elements
344 /// in-place, which allows it to avoid heap allocation when the actual number of
345 /// elements is below that threshold. This allows normal "small" cases to be
346 /// fast without losing generality for large inputs.
348 /// Note that this does not attempt to be exception safe.
350 template <typename T, unsigned N>
351 class SmallVector : public SmallVectorImpl<T> {
352 /// InlineElts - These are 'N-1' elements that are stored inline in the body
353 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
354 typedef typename SmallVectorImpl<T>::U U;
356 // MinUs - The number of U's require to cover N T's.
357 MinUs = (sizeof(T)*N+sizeof(U)-1)/sizeof(U),
359 // NumInlineEltsElts - The number of elements actually in this array. There
360 // is already one in the parent class, and we have to round up to avoid
361 // having a zero-element array.
362 NumInlineEltsElts = (MinUs - 1) > 0 ? (MinUs - 1) : 1,
364 // NumTsAvailable - The number of T's we actually have space for, which may
365 // be more than N due to rounding.
366 NumTsAvailable = (NumInlineEltsElts+1)*sizeof(U) / sizeof(T)
368 U InlineElts[NumInlineEltsElts];
370 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
373 template<typename ItTy>
374 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
378 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
382 const SmallVector &operator=(const SmallVector &RHS) {
383 SmallVectorImpl<T>::operator=(RHS);
388 } // End llvm namespace
391 /// Implement std::swap in terms of SmallVector swap.
394 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
398 /// Implement std::swap in terms of SmallVector swap.
399 template<typename T, unsigned N>
401 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {