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"
18 #include "llvm/Support/type_traits.h"
27 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
28 // additional overloads so that elements with pointer types are recognized as
29 // scalars and not objects, causing bizarre type conversion errors.
30 template<class T1, class T2>
31 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
32 _Scalar_ptr_iterator_tag _Cat;
36 template<class T1, class T2>
37 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
38 _Scalar_ptr_iterator_tag _Cat;
42 // FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
43 // is that the above hack won't work if it wasn't fixed.
50 /// SmallVectorImpl - This class consists of common code factored out of the
51 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
52 /// template parameter.
54 class SmallVectorImpl {
56 T *Begin, *End, *Capacity;
58 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
59 // don't want it to be automatically run, so we need to represent the space as
60 // something else. An array of char would work great, but might not be
61 // aligned sufficiently. Instead, we either use GCC extensions, or some
62 // number of union instances for the space, which guarantee maximal alignment.
66 U FirstEl __attribute__((aligned));
75 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
77 // Default ctor - Initialize to empty.
78 SmallVectorImpl(unsigned N)
79 : Begin(reinterpret_cast<T*>(&FirstEl)),
80 End(reinterpret_cast<T*>(&FirstEl)),
81 Capacity(reinterpret_cast<T*>(&FirstEl)+N) {
85 // Destroy the constructed elements in the vector.
86 destroy_range(Begin, End);
88 // If this wasn't grown from the inline copy, deallocate the old space.
90 operator delete(Begin);
93 typedef size_t size_type;
96 typedef const T* const_iterator;
98 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
99 typedef std::reverse_iterator<iterator> reverse_iterator;
101 typedef T& reference;
102 typedef const T& const_reference;
104 bool empty() const { return Begin == End; }
105 size_type size() const { return End-Begin; }
107 // forward iterator creation methods.
108 iterator begin() { return Begin; }
109 const_iterator begin() const { return Begin; }
110 iterator end() { return End; }
111 const_iterator end() const { return End; }
113 // reverse iterator creation methods.
114 reverse_iterator rbegin() { return reverse_iterator(end()); }
115 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
116 reverse_iterator rend() { return reverse_iterator(begin()); }
117 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
120 /* These asserts could be "Begin + idx < End", but there are lots of places
121 in llvm where we use &v[v.size()] instead of v.end(). */
122 reference operator[](unsigned idx) {
123 assert (Begin + idx <= End);
126 const_reference operator[](unsigned idx) const {
127 assert (Begin + idx <= End);
134 const_reference front() const {
141 const_reference back() const {
145 void push_back(const_reference Elt) {
146 if (End < Capacity) {
162 destroy_range(Begin, End);
166 void resize(unsigned N) {
168 destroy_range(Begin+N, End);
170 } else if (N > size()) {
171 if (unsigned(Capacity-Begin) < N)
173 construct_range(End, Begin+N, T());
178 void resize(unsigned N, const T &NV) {
180 destroy_range(Begin+N, End);
182 } else if (N > size()) {
183 if (unsigned(Capacity-Begin) < N)
185 construct_range(End, Begin+N, NV);
190 void reserve(unsigned N) {
191 if (unsigned(Capacity-Begin) < N)
195 void swap(SmallVectorImpl &RHS);
197 /// append - Add the specified range to the end of the SmallVector.
199 template<typename in_iter>
200 void append(in_iter in_start, in_iter in_end) {
201 size_type NumInputs = std::distance(in_start, in_end);
202 // Grow allocated space if needed.
203 if (End+NumInputs > Capacity)
204 grow(size()+NumInputs);
206 // Copy the new elements over.
207 std::uninitialized_copy(in_start, in_end, End);
211 void assign(unsigned NumElts, const T &Elt) {
213 if (unsigned(Capacity-Begin) < NumElts)
216 construct_range(Begin, End, Elt);
219 iterator erase(iterator I) {
221 // Shift all elts down one.
222 std::copy(I+1, End, I);
223 // Drop the last elt.
228 iterator erase(iterator S, iterator E) {
230 // Shift all elts down.
231 iterator I = std::copy(E, End, S);
232 // Drop the last elts.
233 destroy_range(I, End);
238 iterator insert(iterator I, const T &Elt) {
239 if (I == End) { // Important special case for empty vector.
244 if (End < Capacity) {
248 // Push everything else over.
249 std::copy_backward(I, End-1, End);
253 size_t EltNo = I-Begin;
259 template<typename ItTy>
260 iterator insert(iterator I, ItTy From, ItTy To) {
261 if (I == End) { // Important special case for empty vector.
266 size_t NumToInsert = std::distance(From, To);
267 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
268 size_t InsertElt = I-begin();
270 // Ensure there is enough space.
271 reserve(static_cast<unsigned>(size() + NumToInsert));
273 // Uninvalidate the iterator.
274 I = begin()+InsertElt;
276 // If we already have this many elements in the collection, append the
277 // dest elements at the end, then copy over the appropriate elements. Since
278 // we already reserved space, we know that this won't reallocate the vector.
279 if (size() >= NumToInsert) {
281 append(End-NumToInsert, End);
283 // Copy the existing elements that get replaced.
284 std::copy(I, OldEnd-NumToInsert, I+NumToInsert);
286 std::copy(From, To, I);
290 // Otherwise, we're inserting more elements than exist already, and we're
291 // not inserting at the end.
293 // Copy over the elements that we're about to overwrite.
296 size_t NumOverwritten = OldEnd-I;
297 std::uninitialized_copy(I, OldEnd, End-NumOverwritten);
299 // Replace the overwritten part.
300 std::copy(From, From+NumOverwritten, I);
302 // Insert the non-overwritten middle part.
303 std::uninitialized_copy(From+NumOverwritten, To, OldEnd);
307 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
309 bool operator==(const SmallVectorImpl &RHS) const {
310 if (size() != RHS.size()) return false;
311 for (T *This = Begin, *That = RHS.Begin, *E = Begin+size();
312 This != E; ++This, ++That)
317 bool operator!=(const SmallVectorImpl &RHS) const { return !(*this == RHS); }
319 bool operator<(const SmallVectorImpl &RHS) const {
320 return std::lexicographical_compare(begin(), end(),
321 RHS.begin(), RHS.end());
325 /// isSmall - Return true if this is a smallvector which has not had dynamic
326 /// memory allocated for it.
327 bool isSmall() const {
328 return static_cast<const void*>(Begin) ==
329 static_cast<const void*>(&FirstEl);
332 /// grow - double the size of the allocated memory, guaranteeing space for at
333 /// least one more element or MinSize if specified.
334 void grow(size_type MinSize = 0);
336 void construct_range(T *S, T *E, const T &Elt) {
341 void destroy_range(T *S, T *E) {
349 // Define this out-of-line to dissuade the C++ compiler from inlining it.
350 template <typename T>
351 void SmallVectorImpl<T>::grow(size_t MinSize) {
352 size_t CurCapacity = Capacity-Begin;
353 size_t CurSize = size();
354 size_t NewCapacity = 2*CurCapacity;
355 if (NewCapacity < MinSize)
356 NewCapacity = MinSize;
357 T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T)));
359 // Copy the elements over.
360 if (is_class<T>::value)
361 std::uninitialized_copy(Begin, End, NewElts);
363 // Use memcpy for PODs (std::uninitialized_copy optimizes to memmove).
364 memcpy(NewElts, Begin, CurSize * sizeof(T));
366 // Destroy the original elements.
367 destroy_range(Begin, End);
369 // If this wasn't grown from the inline copy, deallocate the old space.
371 operator delete(Begin);
374 End = NewElts+CurSize;
375 Capacity = Begin+NewCapacity;
378 template <typename T>
379 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
380 if (this == &RHS) return;
382 // We can only avoid copying elements if neither vector is small.
383 if (!isSmall() && !RHS.isSmall()) {
384 std::swap(Begin, RHS.Begin);
385 std::swap(End, RHS.End);
386 std::swap(Capacity, RHS.Capacity);
389 if (Begin+RHS.size() > Capacity)
391 if (RHS.begin()+size() > RHS.Capacity)
394 // Swap the shared elements.
395 size_t NumShared = size();
396 if (NumShared > RHS.size()) NumShared = RHS.size();
397 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
398 std::swap(Begin[i], RHS[i]);
400 // Copy over the extra elts.
401 if (size() > RHS.size()) {
402 size_t EltDiff = size() - RHS.size();
403 std::uninitialized_copy(Begin+NumShared, End, RHS.End);
405 destroy_range(Begin+NumShared, End);
406 End = Begin+NumShared;
407 } else if (RHS.size() > size()) {
408 size_t EltDiff = RHS.size() - size();
409 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
411 destroy_range(RHS.Begin+NumShared, RHS.End);
412 RHS.End = RHS.Begin+NumShared;
416 template <typename T>
417 const SmallVectorImpl<T> &
418 SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
419 // Avoid self-assignment.
420 if (this == &RHS) return *this;
422 // If we already have sufficient space, assign the common elements, then
423 // destroy any excess.
424 unsigned RHSSize = unsigned(RHS.size());
425 unsigned CurSize = unsigned(size());
426 if (CurSize >= RHSSize) {
427 // Assign common elements.
430 NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
434 // Destroy excess elements.
435 destroy_range(NewEnd, End);
442 // If we have to grow to have enough elements, destroy the current elements.
443 // This allows us to avoid copying them during the grow.
444 if (unsigned(Capacity-Begin) < RHSSize) {
445 // Destroy current elements.
446 destroy_range(Begin, End);
450 } else if (CurSize) {
451 // Otherwise, use assignment for the already-constructed elements.
452 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
455 // Copy construct the new elements in place.
456 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
463 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
464 /// for the case when the array is small. It contains some number of elements
465 /// in-place, which allows it to avoid heap allocation when the actual number of
466 /// elements is below that threshold. This allows normal "small" cases to be
467 /// fast without losing generality for large inputs.
469 /// Note that this does not attempt to be exception safe.
471 template <typename T, unsigned N>
472 class SmallVector : public SmallVectorImpl<T> {
473 /// InlineElts - These are 'N-1' elements that are stored inline in the body
474 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
475 typedef typename SmallVectorImpl<T>::U U;
477 // MinUs - The number of U's require to cover N T's.
478 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
479 static_cast<unsigned int>(sizeof(U)) - 1) /
480 static_cast<unsigned int>(sizeof(U)),
482 // NumInlineEltsElts - The number of elements actually in this array. There
483 // is already one in the parent class, and we have to round up to avoid
484 // having a zero-element array.
485 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
487 // NumTsAvailable - The number of T's we actually have space for, which may
488 // be more than N due to rounding.
489 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
490 static_cast<unsigned int>(sizeof(T))
492 U InlineElts[NumInlineEltsElts];
494 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
497 explicit SmallVector(unsigned Size, const T &Value = T())
498 : SmallVectorImpl<T>(NumTsAvailable) {
504 template<typename ItTy>
505 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
509 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
514 const SmallVector &operator=(const SmallVector &RHS) {
515 SmallVectorImpl<T>::operator=(RHS);
521 } // End llvm namespace
524 /// Implement std::swap in terms of SmallVector swap.
527 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
531 /// Implement std::swap in terms of SmallVector swap.
532 template<typename T, unsigned N>
534 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {