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
24 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
25 // additional overloads so that elements with pointer types are recognized as
26 // scalars and not objects, causing bizarre type conversion errors.
27 template<class T1, class T2>
28 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
29 _Scalar_ptr_iterator_tag _Cat;
33 template<class T1, class T2>
34 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
35 _Scalar_ptr_iterator_tag _Cat;
39 // FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
40 // is that the above hack won't work if it wasn't fixed.
47 /// SmallVectorImpl - This class consists of common code factored out of the
48 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
49 /// template parameter.
51 class SmallVectorImpl {
53 T *Begin, *End, *Capacity;
55 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
56 // don't want it to be automatically run, so we need to represent the space as
57 // something else. An array of char would work great, but might not be
58 // aligned sufficiently. Instead, we either use GCC extensions, or some
59 // number of union instances for the space, which guarantee maximal alignment.
63 U FirstEl __attribute__((aligned));
72 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
74 // Default ctor - Initialize to empty.
75 SmallVectorImpl(unsigned N)
76 : Begin((T*)&FirstEl), End((T*)&FirstEl), Capacity((T*)&FirstEl+N) {
80 // Destroy the constructed elements in the vector.
81 destroy_range(Begin, End);
83 // If this wasn't grown from the inline copy, deallocate the old space.
85 delete[] (char*)Begin;
88 typedef size_t size_type;
90 typedef const T* const_iterator;
92 typedef const T& const_reference;
94 bool empty() const { return Begin == End; }
95 size_type size() const { return End-Begin; }
97 iterator begin() { return Begin; }
98 const_iterator begin() const { return Begin; }
100 iterator end() { return End; }
101 const_iterator end() const { return End; }
103 reference operator[](unsigned idx) {
106 const_reference operator[](unsigned idx) const {
113 const_reference front() const {
120 const_reference back() const {
124 void push_back(const_reference Elt) {
125 if (End < Capacity) {
141 destroy_range(Begin, End);
145 void resize(unsigned N) {
147 destroy_range(Begin+N, End);
149 } else if (N > size()) {
150 if (Begin+N > Capacity)
152 construct_range(End, Begin+N, T());
157 void resize(unsigned N, const T &NV) {
159 destroy_range(Begin+N, End);
161 } else if (N > size()) {
162 if (Begin+N > Capacity)
164 construct_range(End, Begin+N, NV);
169 void reserve(unsigned N) {
170 if (unsigned(Capacity-Begin) < N)
174 void swap(SmallVectorImpl &RHS);
176 /// append - Add the specified range to the end of the SmallVector.
178 template<typename in_iter>
179 void append(in_iter in_start, in_iter in_end) {
180 unsigned NumInputs = std::distance(in_start, in_end);
181 // Grow allocated space if needed.
182 if (End+NumInputs > Capacity)
183 grow(size()+NumInputs);
185 // Copy the new elements over.
186 std::uninitialized_copy(in_start, in_end, End);
190 void assign(unsigned NumElts, const T &Elt) {
192 if (Begin+NumElts > Capacity)
195 construct_range(Begin, End, Elt);
198 void erase(iterator I) {
199 // Shift all elts down one.
200 std::copy(I+1, End, I);
201 // Drop the last elt.
205 void erase(iterator S, iterator E) {
206 // Shift all elts down.
207 iterator I = std::copy(E, End, S);
208 // Drop the last elts.
209 destroy_range(I, End);
213 iterator insert(iterator I, const T &Elt) {
214 if (I == End) { // Important special case for empty vector.
219 if (End < Capacity) {
223 // Push everything else over.
224 std::copy_backward(I, End-1, End);
228 unsigned EltNo = I-Begin;
234 template<typename ItTy>
235 iterator insert(iterator I, ItTy From, ItTy To) {
236 if (I == End) { // Important special case for empty vector.
241 unsigned NumToInsert = std::distance(From, To);
242 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
243 unsigned InsertElt = I-begin();
245 // Ensure there is enough space.
246 reserve(size() + NumToInsert);
248 // Uninvalidate the iterator.
249 I = begin()+InsertElt;
251 // If we already have this many elements in the collection, append the
252 // dest elements at the end, then copy over the appropriate elements. Since
253 // we already reserved space, we know that this won't reallocate the vector.
254 if (size() >= NumToInsert) {
256 append(End-NumToInsert, End);
258 // Copy the existing elements that get replaced.
259 std::copy(I, OldEnd-NumToInsert, I+NumToInsert);
261 std::copy(From, To, I);
265 // Otherwise, we're inserting more elements than exist already, and we're
266 // not inserting at the end.
268 // Copy over the elements that we're about to overwrite.
271 unsigned NumOverwritten = OldEnd-I;
272 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
274 // Replace the overwritten part.
275 std::copy(From, From+NumOverwritten, I);
277 // Insert the non-overwritten middle part.
278 std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
282 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
285 /// isSmall - Return true if this is a smallvector which has not had dynamic
286 /// memory allocated for it.
287 bool isSmall() const {
288 return (void*)Begin == (void*)&FirstEl;
291 /// grow - double the size of the allocated memory, guaranteeing space for at
292 /// least one more element or MinSize if specified.
293 void grow(unsigned MinSize = 0);
295 void construct_range(T *S, T *E, const T &Elt) {
300 void destroy_range(T *S, T *E) {
308 // Define this out-of-line to dissuade the C++ compiler from inlining it.
309 template <typename T>
310 void SmallVectorImpl<T>::grow(unsigned MinSize) {
311 unsigned CurCapacity = Capacity-Begin;
312 unsigned CurSize = size();
313 unsigned NewCapacity = 2*CurCapacity;
314 if (NewCapacity < MinSize)
315 NewCapacity = MinSize;
316 T *NewElts = reinterpret_cast<T*>(new char[NewCapacity*sizeof(T)]);
318 // Copy the elements over.
319 std::uninitialized_copy(Begin, End, NewElts);
321 // Destroy the original elements.
322 destroy_range(Begin, End);
324 // If this wasn't grown from the inline copy, deallocate the old space.
326 delete[] (char*)Begin;
329 End = NewElts+CurSize;
330 Capacity = Begin+NewCapacity;
333 template <typename T>
334 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
335 if (this == &RHS) return;
337 // We can only avoid copying elements if neither vector is small.
338 if (!isSmall() && !RHS.isSmall()) {
339 std::swap(Begin, RHS.Begin);
340 std::swap(End, RHS.End);
341 std::swap(Capacity, RHS.Capacity);
344 if (Begin+RHS.size() > Capacity)
346 if (RHS.begin()+size() > RHS.Capacity)
349 // Swap the shared elements.
350 unsigned NumShared = size();
351 if (NumShared > RHS.size()) NumShared = RHS.size();
352 for (unsigned i = 0; i != NumShared; ++i)
353 std::swap(Begin[i], RHS[i]);
355 // Copy over the extra elts.
356 if (size() > RHS.size()) {
357 unsigned EltDiff = size() - RHS.size();
358 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
360 destroy_range(Begin+NumShared, End);
361 End = Begin+NumShared;
362 } else if (RHS.size() > size()) {
363 unsigned EltDiff = RHS.size() - size();
364 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
366 destroy_range(RHS.Begin+NumShared, RHS.End);
367 RHS.End = RHS.Begin+NumShared;
371 template <typename T>
372 const SmallVectorImpl<T> &
373 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
374 // Avoid self-assignment.
375 if (this == &RHS) return *this;
377 // If we already have sufficient space, assign the common elements, then
378 // destroy any excess.
379 unsigned RHSSize = RHS.size();
380 unsigned CurSize = size();
381 if (CurSize >= RHSSize) {
382 // Assign common elements.
383 iterator NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
385 // Destroy excess elements.
386 destroy_range(NewEnd, End);
393 // If we have to grow to have enough elements, destroy the current elements.
394 // This allows us to avoid copying them during the grow.
395 if (unsigned(Capacity-Begin) < RHSSize) {
396 // Destroy current elements.
397 destroy_range(Begin, End);
401 } else if (CurSize) {
402 // Otherwise, use assignment for the already-constructed elements.
403 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
406 // Copy construct the new elements in place.
407 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
414 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
415 /// for the case when the array is small. It contains some number of elements
416 /// in-place, which allows it to avoid heap allocation when the actual number of
417 /// elements is below that threshold. This allows normal "small" cases to be
418 /// fast without losing generality for large inputs.
420 /// Note that this does not attempt to be exception safe.
422 template <typename T, unsigned N>
423 class SmallVector : public SmallVectorImpl<T> {
424 /// InlineElts - These are 'N-1' elements that are stored inline in the body
425 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
426 typedef typename SmallVectorImpl<T>::U U;
428 // MinUs - The number of U's require to cover N T's.
429 MinUs = (sizeof(T)*N+sizeof(U)-1)/sizeof(U),
431 // NumInlineEltsElts - The number of elements actually in this array. There
432 // is already one in the parent class, and we have to round up to avoid
433 // having a zero-element array.
434 NumInlineEltsElts = (MinUs - 1) > 0 ? (MinUs - 1) : 1,
436 // NumTsAvailable - The number of T's we actually have space for, which may
437 // be more than N due to rounding.
438 NumTsAvailable = (NumInlineEltsElts+1)*sizeof(U) / sizeof(T)
440 U InlineElts[NumInlineEltsElts];
442 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
445 SmallVector(unsigned Size, const T &Value)
446 : SmallVectorImpl<T>(NumTsAvailable) {
452 template<typename ItTy>
453 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
457 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
461 const SmallVector &operator=(const SmallVector &RHS) {
462 SmallVectorImpl<T>::operator=(RHS);
467 } // End llvm namespace
470 /// Implement std::swap in terms of SmallVector swap.
473 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
477 /// Implement std::swap in terms of SmallVector swap.
478 template<typename T, unsigned N>
480 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {