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 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
24 // additional overloads so that elements with pointer types are recognized as
25 // scalars and not objects, causing bizarre type conversion errors.
26 // FIXME: this hack may or may not be correct for Visual Studio 2005.
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;
43 /// SmallVectorImpl - This class consists of common code factored out of the
44 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
45 /// template parameter.
47 class SmallVectorImpl {
49 T *Begin, *End, *Capacity;
51 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
52 // don't want it to be automatically run, so we need to represent the space as
53 // something else. An array of char would work great, but might not be
54 // aligned sufficiently. Instead, we either use GCC extensions, or some
55 // number of union instances for the space, which guarantee maximal alignment.
59 U FirstEl __attribute__((aligned));
68 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
70 // Default ctor - Initialize to empty.
71 SmallVectorImpl(unsigned N)
72 : Begin((T*)&FirstEl), End((T*)&FirstEl), Capacity((T*)&FirstEl+N) {
76 // Destroy the constructed elements in the vector.
77 destroy_range(Begin, End);
79 // If this wasn't grown from the inline copy, deallocate the old space.
81 delete[] (char*)Begin;
84 typedef size_t size_type;
86 typedef const T* const_iterator;
88 typedef const T& const_reference;
90 bool empty() const { return Begin == End; }
91 size_type size() const { return End-Begin; }
93 iterator begin() { return Begin; }
94 const_iterator begin() const { return Begin; }
96 iterator end() { return End; }
97 const_iterator end() const { return End; }
99 reference operator[](unsigned idx) {
102 const_reference operator[](unsigned idx) const {
109 const_reference front() const {
116 const_reference back() const {
120 void push_back(const_reference Elt) {
121 if (End < Capacity) {
137 destroy_range(Begin, End);
141 void resize(unsigned N) {
143 destroy_range(Begin+N, End);
145 } else if (N > size()) {
146 if (Begin+N > Capacity)
148 construct_range(End, Begin+N, T());
153 void resize(unsigned N, const T &NV) {
155 destroy_range(Begin+N, End);
157 } else if (N > size()) {
158 if (Begin+N > Capacity)
160 construct_range(End, Begin+N, NV);
165 void reserve(unsigned N) {
166 if (unsigned(Capacity-Begin) < N)
170 void swap(SmallVectorImpl &RHS);
172 /// append - Add the specified range to the end of the SmallVector.
174 template<typename in_iter>
175 void append(in_iter in_start, in_iter in_end) {
176 unsigned NumInputs = std::distance(in_start, in_end);
177 // Grow allocated space if needed.
178 if (End+NumInputs > Capacity)
179 grow(size()+NumInputs);
181 // Copy the new elements over.
182 std::uninitialized_copy(in_start, in_end, End);
186 void assign(unsigned NumElts, const T &Elt) {
188 if (Begin+NumElts > Capacity)
191 construct_range(Begin, End, Elt);
194 void erase(iterator I) {
195 // Shift all elts down one.
196 std::copy(I+1, End, I);
197 // Drop the last elt.
201 void erase(iterator S, iterator E) {
202 // Shift all elts down.
203 iterator I = std::copy(E, End, S);
204 // Drop the last elts.
205 destroy_range(I, End);
209 iterator insert(iterator I, const T &Elt) {
210 if (I == End) { // Important special case for empty vector.
215 if (End < Capacity) {
219 // Push everything else over.
220 std::copy_backward(I, End-1, End);
224 unsigned EltNo = I-Begin;
230 template<typename ItTy>
231 iterator insert(iterator I, ItTy From, ItTy To) {
232 if (I == End) { // Important special case for empty vector.
237 unsigned NumToInsert = std::distance(From, To);
238 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
239 unsigned InsertElt = I-begin();
241 // Ensure there is enough space.
242 reserve(size() + NumToInsert);
244 // Uninvalidate the iterator.
245 I = begin()+InsertElt;
247 // If we already have this many elements in the collection, append the
248 // dest elements at the end, then copy over the appropriate elements. Since
249 // we already reserved space, we know that this won't reallocate the vector.
250 if (size() >= NumToInsert) {
252 append(End-NumToInsert, End);
254 // Copy the existing elements that get replaced.
255 std::copy(I, OldEnd-NumToInsert, I+NumToInsert);
257 std::copy(From, To, I);
261 // Otherwise, we're inserting more elements than exist already, and we're
262 // not inserting at the end.
264 // Copy over the elements that we're about to overwrite.
267 unsigned NumOverwritten = OldEnd-I;
268 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
270 // Replace the overwritten part.
271 std::copy(From, From+NumOverwritten, I);
273 // Insert the non-overwritten middle part.
274 std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
278 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
281 /// isSmall - Return true if this is a smallvector which has not had dynamic
282 /// memory allocated for it.
283 bool isSmall() const {
284 return (void*)Begin == (void*)&FirstEl;
287 /// grow - double the size of the allocated memory, guaranteeing space for at
288 /// least one more element or MinSize if specified.
289 void grow(unsigned MinSize = 0);
291 void construct_range(T *S, T *E, const T &Elt) {
296 void destroy_range(T *S, T *E) {
304 // Define this out-of-line to dissuade the C++ compiler from inlining it.
305 template <typename T>
306 void SmallVectorImpl<T>::grow(unsigned MinSize) {
307 unsigned CurCapacity = Capacity-Begin;
308 unsigned CurSize = size();
309 unsigned NewCapacity = 2*CurCapacity;
310 if (NewCapacity < MinSize)
311 NewCapacity = MinSize;
312 T *NewElts = reinterpret_cast<T*>(new char[NewCapacity*sizeof(T)]);
314 // Copy the elements over.
315 std::uninitialized_copy(Begin, End, NewElts);
317 // Destroy the original elements.
318 destroy_range(Begin, End);
320 // If this wasn't grown from the inline copy, deallocate the old space.
322 delete[] (char*)Begin;
325 End = NewElts+CurSize;
326 Capacity = Begin+NewCapacity;
329 template <typename T>
330 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
331 if (this == &RHS) return;
333 // We can only avoid copying elements if neither vector is small.
334 if (!isSmall() && !RHS.isSmall()) {
335 std::swap(Begin, RHS.Begin);
336 std::swap(End, RHS.End);
337 std::swap(Capacity, RHS.Capacity);
340 if (Begin+RHS.size() > Capacity)
342 if (RHS.begin()+size() > RHS.Capacity)
345 // Swap the shared elements.
346 unsigned NumShared = size();
347 if (NumShared > RHS.size()) NumShared = RHS.size();
348 for (unsigned i = 0; i != NumShared; ++i)
349 std::swap(Begin[i], RHS[i]);
351 // Copy over the extra elts.
352 if (size() > RHS.size()) {
353 unsigned EltDiff = size() - RHS.size();
354 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
356 destroy_range(Begin+NumShared, End);
357 End = Begin+NumShared;
358 } else if (RHS.size() > size()) {
359 unsigned EltDiff = RHS.size() - size();
360 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
362 destroy_range(RHS.Begin+NumShared, RHS.End);
363 RHS.End = RHS.Begin+NumShared;
367 template <typename T>
368 const SmallVectorImpl<T> &
369 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
370 // Avoid self-assignment.
371 if (this == &RHS) return *this;
373 // If we already have sufficient space, assign the common elements, then
374 // destroy any excess.
375 unsigned RHSSize = RHS.size();
376 unsigned CurSize = size();
377 if (CurSize >= RHSSize) {
378 // Assign common elements.
379 iterator NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
381 // Destroy excess elements.
382 destroy_range(NewEnd, End);
389 // If we have to grow to have enough elements, destroy the current elements.
390 // This allows us to avoid copying them during the grow.
391 if (unsigned(Capacity-Begin) < RHSSize) {
392 // Destroy current elements.
393 destroy_range(Begin, End);
397 } else if (CurSize) {
398 // Otherwise, use assignment for the already-constructed elements.
399 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
402 // Copy construct the new elements in place.
403 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
410 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
411 /// for the case when the array is small. It contains some number of elements
412 /// in-place, which allows it to avoid heap allocation when the actual number of
413 /// elements is below that threshold. This allows normal "small" cases to be
414 /// fast without losing generality for large inputs.
416 /// Note that this does not attempt to be exception safe.
418 template <typename T, unsigned N>
419 class SmallVector : public SmallVectorImpl<T> {
420 /// InlineElts - These are 'N-1' elements that are stored inline in the body
421 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
422 typedef typename SmallVectorImpl<T>::U U;
424 // MinUs - The number of U's require to cover N T's.
425 MinUs = (sizeof(T)*N+sizeof(U)-1)/sizeof(U),
427 // NumInlineEltsElts - The number of elements actually in this array. There
428 // is already one in the parent class, and we have to round up to avoid
429 // having a zero-element array.
430 NumInlineEltsElts = (MinUs - 1) > 0 ? (MinUs - 1) : 1,
432 // NumTsAvailable - The number of T's we actually have space for, which may
433 // be more than N due to rounding.
434 NumTsAvailable = (NumInlineEltsElts+1)*sizeof(U) / sizeof(T)
436 U InlineElts[NumInlineEltsElts];
438 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
441 SmallVector(unsigned Size, const T &Value)
442 : SmallVectorImpl<T>(NumTsAvailable) {
448 template<typename ItTy>
449 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
453 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
457 const SmallVector &operator=(const SmallVector &RHS) {
458 SmallVectorImpl<T>::operator=(RHS);
463 } // End llvm namespace
466 /// Implement std::swap in terms of SmallVector swap.
469 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
473 /// Implement std::swap in terms of SmallVector swap.
474 template<typename T, unsigned N>
476 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {