1 //===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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
17 #include "llvm/ADT/iterator.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(reinterpret_cast<T*>(&FirstEl)),
77 End(reinterpret_cast<T*>(&FirstEl)),
78 Capacity(reinterpret_cast<T*>(&FirstEl)+N) {
82 // Destroy the constructed elements in the vector.
83 destroy_range(Begin, End);
85 // If this wasn't grown from the inline copy, deallocate the old space.
87 delete[] reinterpret_cast<char*>(Begin);
90 typedef size_t size_type;
92 typedef const T* const_iterator;
94 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
95 typedef std::reverse_iterator<iterator> reverse_iterator;
98 typedef const T& const_reference;
100 bool empty() const { return Begin == End; }
101 size_type size() const { return End-Begin; }
103 // forward iterator creation methods.
104 iterator begin() { return Begin; }
105 const_iterator begin() const { return Begin; }
106 iterator end() { return End; }
107 const_iterator end() const { return End; }
109 // reverse iterator creation methods.
110 reverse_iterator rbegin() { return reverse_iterator(end()); }
111 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
112 reverse_iterator rend() { return reverse_iterator(begin()); }
113 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
116 reference operator[](unsigned idx) {
119 const_reference operator[](unsigned idx) const {
126 const_reference front() const {
133 const_reference back() const {
137 void push_back(const_reference Elt) {
138 if (End < Capacity) {
154 destroy_range(Begin, End);
158 void resize(unsigned N) {
160 destroy_range(Begin+N, End);
162 } else if (N > size()) {
163 if (unsigned(Capacity-Begin) < N)
165 construct_range(End, Begin+N, T());
170 void resize(unsigned N, const T &NV) {
172 destroy_range(Begin+N, End);
174 } else if (N > size()) {
175 if (unsigned(Capacity-Begin) < N)
177 construct_range(End, Begin+N, NV);
182 void reserve(unsigned N) {
183 if (unsigned(Capacity-Begin) < N)
187 void swap(SmallVectorImpl &RHS);
189 /// append - Add the specified range to the end of the SmallVector.
191 template<typename in_iter>
192 void append(in_iter in_start, in_iter in_end) {
193 size_type NumInputs = std::distance(in_start, in_end);
194 // Grow allocated space if needed.
195 if (End+NumInputs > Capacity)
196 grow(size()+NumInputs);
198 // Copy the new elements over.
199 std::uninitialized_copy(in_start, in_end, End);
203 void assign(unsigned NumElts, const T &Elt) {
205 if (unsigned(Capacity-Begin) < NumElts)
208 construct_range(Begin, End, Elt);
211 iterator erase(iterator I) {
213 // Shift all elts down one.
214 std::copy(I+1, End, I);
215 // Drop the last elt.
220 iterator erase(iterator S, iterator E) {
222 // Shift all elts down.
223 iterator I = std::copy(E, End, S);
224 // Drop the last elts.
225 destroy_range(I, End);
230 iterator insert(iterator I, const T &Elt) {
231 if (I == End) { // Important special case for empty vector.
236 if (End < Capacity) {
240 // Push everything else over.
241 std::copy_backward(I, End-1, End);
245 size_t EltNo = I-Begin;
251 template<typename ItTy>
252 iterator insert(iterator I, ItTy From, ItTy To) {
253 if (I == End) { // Important special case for empty vector.
258 size_t NumToInsert = std::distance(From, To);
259 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
260 size_t InsertElt = I-begin();
262 // Ensure there is enough space.
263 reserve(static_cast<unsigned>(size() + NumToInsert));
265 // Uninvalidate the iterator.
266 I = begin()+InsertElt;
268 // If we already have this many elements in the collection, append the
269 // dest elements at the end, then copy over the appropriate elements. Since
270 // we already reserved space, we know that this won't reallocate the vector.
271 if (size() >= NumToInsert) {
273 append(End-NumToInsert, End);
275 // Copy the existing elements that get replaced.
276 std::copy(I, OldEnd-NumToInsert, I+NumToInsert);
278 std::copy(From, To, I);
282 // Otherwise, we're inserting more elements than exist already, and we're
283 // not inserting at the end.
285 // Copy over the elements that we're about to overwrite.
288 size_t NumOverwritten = OldEnd-I;
289 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
291 // Replace the overwritten part.
292 std::copy(From, From+NumOverwritten, I);
294 // Insert the non-overwritten middle part.
295 std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
299 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
301 bool operator==(const SmallVectorImpl &RHS) const {
302 if (size() != RHS.size()) return false;
303 for (T *This = Begin, *That = RHS.Begin, *E = Begin+size();
304 This != E; ++This, ++That)
309 bool operator!=(const SmallVectorImpl &RHS) const { return !(*this == RHS); }
311 bool operator<(const SmallVectorImpl &RHS) const {
312 return std::lexicographical_compare(begin(), end(),
313 RHS.begin(), RHS.end());
317 /// isSmall - Return true if this is a smallvector which has not had dynamic
318 /// memory allocated for it.
319 bool isSmall() const {
320 return reinterpret_cast<const void*>(Begin) ==
321 reinterpret_cast<const void*>(&FirstEl);
324 /// grow - double the size of the allocated memory, guaranteeing space for at
325 /// least one more element or MinSize if specified.
326 void grow(size_type MinSize = 0);
328 void construct_range(T *S, T *E, const T &Elt) {
333 void destroy_range(T *S, T *E) {
341 // Define this out-of-line to dissuade the C++ compiler from inlining it.
342 template <typename T>
343 void SmallVectorImpl<T>::grow(size_t MinSize) {
344 size_t CurCapacity = Capacity-Begin;
345 size_t CurSize = size();
346 size_t NewCapacity = 2*CurCapacity;
347 if (NewCapacity < MinSize)
348 NewCapacity = MinSize;
349 T *NewElts = reinterpret_cast<T*>(new char[NewCapacity*sizeof(T)]);
351 // Copy the elements over.
352 std::uninitialized_copy(Begin, End, NewElts);
354 // Destroy the original elements.
355 destroy_range(Begin, End);
357 // If this wasn't grown from the inline copy, deallocate the old space.
359 delete[] reinterpret_cast<char*>(Begin);
362 End = NewElts+CurSize;
363 Capacity = Begin+NewCapacity;
366 template <typename T>
367 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
368 if (this == &RHS) return;
370 // We can only avoid copying elements if neither vector is small.
371 if (!isSmall() && !RHS.isSmall()) {
372 std::swap(Begin, RHS.Begin);
373 std::swap(End, RHS.End);
374 std::swap(Capacity, RHS.Capacity);
377 if (Begin+RHS.size() > Capacity)
379 if (RHS.begin()+size() > RHS.Capacity)
382 // Swap the shared elements.
383 size_t NumShared = size();
384 if (NumShared > RHS.size()) NumShared = RHS.size();
385 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
386 std::swap(Begin[i], RHS[i]);
388 // Copy over the extra elts.
389 if (size() > RHS.size()) {
390 size_t EltDiff = size() - RHS.size();
391 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
393 destroy_range(Begin+NumShared, End);
394 End = Begin+NumShared;
395 } else if (RHS.size() > size()) {
396 size_t EltDiff = RHS.size() - size();
397 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
399 destroy_range(RHS.Begin+NumShared, RHS.End);
400 RHS.End = RHS.Begin+NumShared;
404 template <typename T>
405 const SmallVectorImpl<T> &
406 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
407 // Avoid self-assignment.
408 if (this == &RHS) return *this;
410 // If we already have sufficient space, assign the common elements, then
411 // destroy any excess.
412 unsigned RHSSize = unsigned(RHS.size());
413 unsigned CurSize = unsigned(size());
414 if (CurSize >= RHSSize) {
415 // Assign common elements.
418 NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
422 // Destroy excess elements.
423 destroy_range(NewEnd, End);
430 // If we have to grow to have enough elements, destroy the current elements.
431 // This allows us to avoid copying them during the grow.
432 if (unsigned(Capacity-Begin) < RHSSize) {
433 // Destroy current elements.
434 destroy_range(Begin, End);
438 } else if (CurSize) {
439 // Otherwise, use assignment for the already-constructed elements.
440 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
443 // Copy construct the new elements in place.
444 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
451 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
452 /// for the case when the array is small. It contains some number of elements
453 /// in-place, which allows it to avoid heap allocation when the actual number of
454 /// elements is below that threshold. This allows normal "small" cases to be
455 /// fast without losing generality for large inputs.
457 /// Note that this does not attempt to be exception safe.
459 template <typename T, unsigned N>
460 class SmallVector : public SmallVectorImpl<T> {
461 /// InlineElts - These are 'N-1' elements that are stored inline in the body
462 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
463 typedef typename SmallVectorImpl<T>::U U;
465 // MinUs - The number of U's require to cover N T's.
466 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
467 static_cast<unsigned int>(sizeof(U)) - 1) /
468 static_cast<unsigned int>(sizeof(U)),
470 // NumInlineEltsElts - The number of elements actually in this array. There
471 // is already one in the parent class, and we have to round up to avoid
472 // having a zero-element array.
473 NumInlineEltsElts = (MinUs - 1) > 0 ? (MinUs - 1) : 1,
475 // NumTsAvailable - The number of T's we actually have space for, which may
476 // be more than N due to rounding.
477 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
478 static_cast<unsigned int>(sizeof(T))
480 U InlineElts[NumInlineEltsElts];
482 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
485 explicit SmallVector(unsigned Size, const T &Value = T())
486 : SmallVectorImpl<T>(NumTsAvailable) {
492 template<typename ItTy>
493 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
497 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
502 const SmallVector &operator=(const SmallVector &RHS) {
503 SmallVectorImpl<T>::operator=(RHS);
509 } // End llvm namespace
512 /// Implement std::swap in terms of SmallVector swap.
515 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
519 /// Implement std::swap in terms of SmallVector swap.
520 template<typename T, unsigned N>
522 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {