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.
42 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
44 // Default ctor - Initialize to empty.
45 SmallVectorImpl(unsigned N)
46 : Begin((T*)&FirstEl), End((T*)&FirstEl), Capacity((T*)&FirstEl+N) {
50 // Destroy the constructed elements in the vector.
51 destroy_range(Begin, End);
53 // If this wasn't grown from the inline copy, deallocate the old space.
55 delete[] (char*)Begin;
58 typedef size_t size_type;
60 typedef const T* const_iterator;
62 typedef const T& const_reference;
64 bool empty() const { return Begin == End; }
65 size_type size() const { return End-Begin; }
67 iterator begin() { return Begin; }
68 const_iterator begin() const { return Begin; }
70 iterator end() { return End; }
71 const_iterator end() const { return End; }
73 reference operator[](unsigned idx) {
76 const_reference operator[](unsigned idx) const {
83 const_reference front() const {
90 const_reference back() const {
94 void push_back(const_reference Elt) {
111 destroy_range(Begin, End);
115 void resize(unsigned N) {
117 destroy_range(Begin+N, End);
119 } else if (N > size()) {
120 if (Begin+N > Capacity)
122 construct_range(End, Begin+N, T());
127 void swap(SmallVectorImpl &RHS);
129 /// append - Add the specified range to the end of the SmallVector.
131 template<typename in_iter>
132 void append(in_iter in_start, in_iter in_end) {
133 unsigned NumInputs = std::distance(in_start, in_end);
134 // Grow allocated space if needed.
135 if (End+NumInputs > Capacity)
136 grow(size()+NumInputs);
138 // Copy the new elements over.
139 std::uninitialized_copy(in_start, in_end, End);
143 void assign(unsigned NumElts, const T &Elt) {
145 if (Begin+NumElts > Capacity)
148 construct_range(Begin, End, Elt);
151 void erase(iterator I) {
152 // Shift all elts down one.
153 std::copy(I+1, End, I);
154 // Drop the last elt.
158 void erase(iterator S, iterator E) {
159 // Shift all elts down.
160 iterator I = std::copy(E, End, S);
161 // Drop the last elts.
162 destroy_range(I, End);
166 iterator insert(iterator I, const T &Elt) {
167 if (I == End) { // Important special case for empty vector.
172 if (End < Capacity) {
176 // Push everything else over.
177 std::copy_backward(I, End-1, End);
181 unsigned EltNo = I-Begin;
187 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
190 /// isSmall - Return true if this is a smallvector which has not had dynamic
191 /// memory allocated for it.
192 bool isSmall() const {
193 return (void*)Begin == (void*)&FirstEl;
196 /// grow - double the size of the allocated memory, guaranteeing space for at
197 /// least one more element or MinSize if specified.
198 void grow(unsigned MinSize = 0);
200 void construct_range(T *S, T *E, const T &Elt) {
206 void destroy_range(T *S, T *E) {
214 // Define this out-of-line to dissuade the C++ compiler from inlining it.
215 template <typename T>
216 void SmallVectorImpl<T>::grow(unsigned MinSize) {
217 unsigned CurCapacity = Capacity-Begin;
218 unsigned CurSize = size();
219 unsigned NewCapacity = 2*CurCapacity;
220 if (NewCapacity < MinSize)
221 NewCapacity = MinSize;
222 T *NewElts = reinterpret_cast<T*>(new char[NewCapacity*sizeof(T)]);
224 // Copy the elements over.
225 std::uninitialized_copy(Begin, End, NewElts);
227 // Destroy the original elements.
228 destroy_range(Begin, End);
230 // If this wasn't grown from the inline copy, deallocate the old space.
232 delete[] (char*)Begin;
235 End = NewElts+CurSize;
236 Capacity = Begin+NewCapacity;
239 template <typename T>
240 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
241 if (this == &RHS) return;
243 // We can only avoid copying elements if neither vector is small.
244 if (!isSmall() && !RHS.isSmall()) {
245 std::swap(Begin, RHS.Begin);
246 std::swap(End, RHS.End);
247 std::swap(Capacity, RHS.Capacity);
250 if (Begin+RHS.size() > Capacity)
252 if (RHS.begin()+size() > RHS.Capacity)
255 // Swap the shared elements.
256 unsigned NumShared = size();
257 if (NumShared > RHS.size()) NumShared = RHS.size();
258 for (unsigned i = 0; i != NumShared; ++i)
259 std::swap(Begin[i], RHS[i]);
261 // Copy over the extra elts.
262 if (size() > RHS.size()) {
263 unsigned EltDiff = size() - RHS.size();
264 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
266 destroy_range(Begin+NumShared, End);
267 End = Begin+NumShared;
268 } else if (RHS.size() > size()) {
269 unsigned EltDiff = RHS.size() - size();
270 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
272 destroy_range(RHS.Begin+NumShared, RHS.End);
273 RHS.End = RHS.Begin+NumShared;
277 template <typename T>
278 const SmallVectorImpl<T> &
279 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
280 // Avoid self-assignment.
281 if (this == &RHS) return *this;
283 // If we already have sufficient space, assign the common elements, then
284 // destroy any excess.
285 unsigned RHSSize = RHS.size();
286 unsigned CurSize = size();
287 if (CurSize >= RHSSize) {
288 // Assign common elements.
289 iterator NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
291 // Destroy excess elements.
292 destroy_range(NewEnd, End);
299 // If we have to grow to have enough elements, destroy the current elements.
300 // This allows us to avoid copying them during the grow.
301 if (unsigned(Capacity-Begin) < RHSSize) {
302 // Destroy current elements.
303 destroy_range(Begin, End);
307 } else if (CurSize) {
308 // Otherwise, use assignment for the already-constructed elements.
309 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
312 // Copy construct the new elements in place.
313 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
320 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
321 /// for the case when the array is small. It contains some number of elements
322 /// in-place, which allows it to avoid heap allocation when the actual number of
323 /// elements is below that threshold. This allows normal "small" cases to be
324 /// fast without losing generality for large inputs.
326 /// Note that this does not attempt to be exception safe.
328 template <typename T, unsigned N>
329 class SmallVector : public SmallVectorImpl<T> {
330 /// InlineElts - These are 'N-1' elements that are stored inline in the body
331 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
332 typedef typename SmallVectorImpl<T>::U U;
334 // MinUs - The number of U's require to cover N T's.
335 MinUs = (sizeof(T)*N+sizeof(U)-1)/sizeof(U),
337 // NumInlineEltsElts - The number of elements actually in this array. There
338 // is already one in the parent class, and we have to round up to avoid
339 // having a zero-element array.
340 NumInlineEltsElts = (MinUs - 1) > 0 ? (MinUs - 1) : 1,
342 // NumTsAvailable - The number of T's we actually have space for, which may
343 // be more than N due to rounding.
344 NumTsAvailable = (NumInlineEltsElts+1)*sizeof(U) / sizeof(T)
346 U InlineElts[NumInlineEltsElts];
348 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
351 template<typename ItTy>
352 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
356 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
360 const SmallVector &operator=(const SmallVector &RHS) {
361 SmallVectorImpl<T>::operator=(RHS);
366 } // End llvm namespace
369 /// Implement std::swap in terms of SmallVector swap.
372 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
376 /// Implement std::swap in terms of SmallVector swap.
377 template<typename T, unsigned N>
379 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {