1 //===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines the SmallVector class.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #ifndef LLVM_ADT_SMALLVECTOR_H
15 #define LLVM_ADT_SMALLVECTOR_H
16
17 #include "llvm/Support/type_traits.h"
18 #include <algorithm>
19 #include <cassert>
20 #include <cstddef>
21 #include <cstdlib>
22 #include <cstring>
23 #include <memory>
24
25 #ifdef _MSC_VER
26 namespace std {
27 #if _MSC_VER <= 1310
28 // Work around flawed VC++ implementation of std::uninitialized_copy. Define
29 // additional overloads so that elements with pointer types are recognized as
30 // scalars and not objects, causing bizarre type conversion errors.
31 template<class T1, class T2>
_Ptr_cat(T1 **,T2 **)32 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1 **, T2 **) {
33 _Scalar_ptr_iterator_tag _Cat;
34 return _Cat;
35 }
36
37 template<class T1, class T2>
_Ptr_cat(T1 * const *,T2 **)38 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) {
39 _Scalar_ptr_iterator_tag _Cat;
40 return _Cat;
41 }
42 #else
43 // FIXME: It is not clear if the problem is fixed in VS 2005. What is clear
44 // is that the above hack won't work if it wasn't fixed.
45 #endif
46 }
47 #endif
48
49 namespace llvm {
50
51 /// SmallVectorBase - This is all the non-templated stuff common to all
52 /// SmallVectors.
53 class SmallVectorBase {
54 protected:
55 void *BeginX, *EndX, *CapacityX;
56
57 // Allocate raw space for N elements of type T. If T has a ctor or dtor, we
58 // don't want it to be automatically run, so we need to represent the space as
59 // something else. An array of char would work great, but might not be
60 // aligned sufficiently. Instead, we either use GCC extensions, or some
61 // number of union instances for the space, which guarantee maximal alignment.
62 #ifdef __GNUC__
63 typedef char U;
64 U FirstEl __attribute__((aligned(8)));
65 #else
66 union U {
67 double D;
68 long double LD;
69 long long L;
70 void *P;
71 } FirstEl;
72 #endif
73 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
74
75 protected:
SmallVectorBase(size_t Size)76 SmallVectorBase(size_t Size)
77 : BeginX(&FirstEl), EndX(&FirstEl), CapacityX((char*)&FirstEl+Size) {}
78
79 /// isSmall - Return true if this is a smallvector which has not had dynamic
80 /// memory allocated for it.
isSmall()81 bool isSmall() const {
82 return BeginX == static_cast<const void*>(&FirstEl);
83 }
84
85 /// size_in_bytes - This returns size()*sizeof(T).
size_in_bytes()86 size_t size_in_bytes() const {
87 return size_t((char*)EndX - (char*)BeginX);
88 }
89
90 /// capacity_in_bytes - This returns capacity()*sizeof(T).
capacity_in_bytes()91 size_t capacity_in_bytes() const {
92 return size_t((char*)CapacityX - (char*)BeginX);
93 }
94
95 /// grow_pod - This is an implementation of the grow() method which only works
96 /// on POD-like datatypes and is out of line to reduce code duplication.
97 void grow_pod(size_t MinSizeInBytes, size_t TSize);
98
99 public:
empty()100 bool empty() const { return BeginX == EndX; }
101 };
102
103
104 template <typename T>
105 class SmallVectorTemplateCommon : public SmallVectorBase {
106 protected:
setEnd(T * P)107 void setEnd(T *P) { this->EndX = P; }
108 public:
SmallVectorTemplateCommon(size_t Size)109 SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(Size) {}
110
111 typedef size_t size_type;
112 typedef ptrdiff_t difference_type;
113 typedef T value_type;
114 typedef T *iterator;
115 typedef const T *const_iterator;
116
117 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
118 typedef std::reverse_iterator<iterator> reverse_iterator;
119
120 typedef T &reference;
121 typedef const T &const_reference;
122 typedef T *pointer;
123 typedef const T *const_pointer;
124
125 // forward iterator creation methods.
begin()126 iterator begin() { return (iterator)this->BeginX; }
begin()127 const_iterator begin() const { return (const_iterator)this->BeginX; }
end()128 iterator end() { return (iterator)this->EndX; }
end()129 const_iterator end() const { return (const_iterator)this->EndX; }
130 protected:
capacity_ptr()131 iterator capacity_ptr() { return (iterator)this->CapacityX; }
capacity_ptr()132 const_iterator capacity_ptr() const { return (const_iterator)this->CapacityX;}
133 public:
134
135 // reverse iterator creation methods.
rbegin()136 reverse_iterator rbegin() { return reverse_iterator(end()); }
rbegin()137 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
rend()138 reverse_iterator rend() { return reverse_iterator(begin()); }
rend()139 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
140
size()141 size_type size() const { return end()-begin(); }
max_size()142 size_type max_size() const { return size_type(-1) / sizeof(T); }
143
144 /// capacity - Return the total number of elements in the currently allocated
145 /// buffer.
capacity()146 size_t capacity() const { return capacity_ptr() - begin(); }
147
148 /// data - Return a pointer to the vector's buffer, even if empty().
data()149 pointer data() { return pointer(begin()); }
150 /// data - Return a pointer to the vector's buffer, even if empty().
data()151 const_pointer data() const { return const_pointer(begin()); }
152
153 reference operator[](unsigned idx) {
154 assert(begin() + idx < end());
155 return begin()[idx];
156 }
157 const_reference operator[](unsigned idx) const {
158 assert(begin() + idx < end());
159 return begin()[idx];
160 }
161
front()162 reference front() {
163 return begin()[0];
164 }
front()165 const_reference front() const {
166 return begin()[0];
167 }
168
back()169 reference back() {
170 return end()[-1];
171 }
back()172 const_reference back() const {
173 return end()[-1];
174 }
175 };
176
177 /// SmallVectorTemplateBase<isPodLike = false> - This is where we put method
178 /// implementations that are designed to work with non-POD-like T's.
179 template <typename T, bool isPodLike>
180 class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
181 public:
SmallVectorTemplateBase(size_t Size)182 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
183
destroy_range(T * S,T * E)184 static void destroy_range(T *S, T *E) {
185 while (S != E) {
186 --E;
187 E->~T();
188 }
189 }
190
191 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
192 /// starting with "Dest", constructing elements into it as needed.
193 template<typename It1, typename It2>
uninitialized_copy(It1 I,It1 E,It2 Dest)194 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
195 std::uninitialized_copy(I, E, Dest);
196 }
197
198 /// grow - double the size of the allocated memory, guaranteeing space for at
199 /// least one more element or MinSize if specified.
200 void grow(size_t MinSize = 0);
201 };
202
203 // Define this out-of-line to dissuade the C++ compiler from inlining it.
204 template <typename T, bool isPodLike>
grow(size_t MinSize)205 void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize) {
206 size_t CurCapacity = this->capacity();
207 size_t CurSize = this->size();
208 size_t NewCapacity = 2*CurCapacity + 1; // Always grow, even from zero.
209 if (NewCapacity < MinSize)
210 NewCapacity = MinSize;
211 T *NewElts = static_cast<T*>(malloc(NewCapacity*sizeof(T)));
212
213 // Copy the elements over.
214 this->uninitialized_copy(this->begin(), this->end(), NewElts);
215
216 // Destroy the original elements.
217 destroy_range(this->begin(), this->end());
218
219 // If this wasn't grown from the inline copy, deallocate the old space.
220 if (!this->isSmall())
221 free(this->begin());
222
223 this->setEnd(NewElts+CurSize);
224 this->BeginX = NewElts;
225 this->CapacityX = this->begin()+NewCapacity;
226 }
227
228
229 /// SmallVectorTemplateBase<isPodLike = true> - This is where we put method
230 /// implementations that are designed to work with POD-like T's.
231 template <typename T>
232 class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
233 public:
SmallVectorTemplateBase(size_t Size)234 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
235
236 // No need to do a destroy loop for POD's.
destroy_range(T *,T *)237 static void destroy_range(T *, T *) {}
238
239 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
240 /// starting with "Dest", constructing elements into it as needed.
241 template<typename It1, typename It2>
uninitialized_copy(It1 I,It1 E,It2 Dest)242 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
243 // Arbitrary iterator types; just use the basic implementation.
244 std::uninitialized_copy(I, E, Dest);
245 }
246
247 /// uninitialized_copy - Copy the range [I, E) onto the uninitialized memory
248 /// starting with "Dest", constructing elements into it as needed.
249 template<typename T1, typename T2>
uninitialized_copy(T1 * I,T1 * E,T2 * Dest)250 static void uninitialized_copy(T1 *I, T1 *E, T2 *Dest) {
251 // Use memcpy for PODs iterated by pointers (which includes SmallVector
252 // iterators): std::uninitialized_copy optimizes to memmove, but we can
253 // use memcpy here.
254 memcpy(Dest, I, (E-I)*sizeof(T));
255 }
256
257 /// grow - double the size of the allocated memory, guaranteeing space for at
258 /// least one more element or MinSize if specified.
259 void grow(size_t MinSize = 0) {
260 this->grow_pod(MinSize*sizeof(T), sizeof(T));
261 }
262 };
263
264
265 /// SmallVectorImpl - This class consists of common code factored out of the
266 /// SmallVector class to reduce code duplication based on the SmallVector 'N'
267 /// template parameter.
268 template <typename T>
269 class SmallVectorImpl : public SmallVectorTemplateBase<T, isPodLike<T>::value> {
270 typedef SmallVectorTemplateBase<T, isPodLike<T>::value > SuperClass;
271
272 SmallVectorImpl(const SmallVectorImpl&); // DISABLED.
273 public:
274 typedef typename SuperClass::iterator iterator;
275 typedef typename SuperClass::size_type size_type;
276
277 // Default ctor - Initialize to empty.
SmallVectorImpl(unsigned N)278 explicit SmallVectorImpl(unsigned N)
279 : SmallVectorTemplateBase<T, isPodLike<T>::value>(N*sizeof(T)) {
280 }
281
~SmallVectorImpl()282 ~SmallVectorImpl() {
283 // Destroy the constructed elements in the vector.
284 this->destroy_range(this->begin(), this->end());
285
286 // If this wasn't grown from the inline copy, deallocate the old space.
287 if (!this->isSmall())
288 free(this->begin());
289 }
290
291
clear()292 void clear() {
293 this->destroy_range(this->begin(), this->end());
294 this->EndX = this->BeginX;
295 }
296
resize(unsigned N)297 void resize(unsigned N) {
298 if (N < this->size()) {
299 this->destroy_range(this->begin()+N, this->end());
300 this->setEnd(this->begin()+N);
301 } else if (N > this->size()) {
302 if (this->capacity() < N)
303 this->grow(N);
304 this->construct_range(this->end(), this->begin()+N, T());
305 this->setEnd(this->begin()+N);
306 }
307 }
308
resize(unsigned N,const T & NV)309 void resize(unsigned N, const T &NV) {
310 if (N < this->size()) {
311 this->destroy_range(this->begin()+N, this->end());
312 this->setEnd(this->begin()+N);
313 } else if (N > this->size()) {
314 if (this->capacity() < N)
315 this->grow(N);
316 construct_range(this->end(), this->begin()+N, NV);
317 this->setEnd(this->begin()+N);
318 }
319 }
320
reserve(unsigned N)321 void reserve(unsigned N) {
322 if (this->capacity() < N)
323 this->grow(N);
324 }
325
push_back(const T & Elt)326 void push_back(const T &Elt) {
327 if (this->EndX < this->CapacityX) {
328 Retry:
329 new (this->end()) T(Elt);
330 this->setEnd(this->end()+1);
331 return;
332 }
333 this->grow();
334 goto Retry;
335 }
336
pop_back()337 void pop_back() {
338 this->setEnd(this->end()-1);
339 this->end()->~T();
340 }
341
pop_back_val()342 T pop_back_val() {
343 T Result = this->back();
344 pop_back();
345 return Result;
346 }
347
348
349 void swap(SmallVectorImpl &RHS);
350
351 /// append - Add the specified range to the end of the SmallVector.
352 ///
353 template<typename in_iter>
append(in_iter in_start,in_iter in_end)354 void append(in_iter in_start, in_iter in_end) {
355 size_type NumInputs = std::distance(in_start, in_end);
356 // Grow allocated space if needed.
357 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
358 this->grow(this->size()+NumInputs);
359
360 // Copy the new elements over.
361 // TODO: NEED To compile time dispatch on whether in_iter is a random access
362 // iterator to use the fast uninitialized_copy.
363 std::uninitialized_copy(in_start, in_end, this->end());
364 this->setEnd(this->end() + NumInputs);
365 }
366
367 /// append - Add the specified range to the end of the SmallVector.
368 ///
append(size_type NumInputs,const T & Elt)369 void append(size_type NumInputs, const T &Elt) {
370 // Grow allocated space if needed.
371 if (NumInputs > size_type(this->capacity_ptr()-this->end()))
372 this->grow(this->size()+NumInputs);
373
374 // Copy the new elements over.
375 std::uninitialized_fill_n(this->end(), NumInputs, Elt);
376 this->setEnd(this->end() + NumInputs);
377 }
378
assign(unsigned NumElts,const T & Elt)379 void assign(unsigned NumElts, const T &Elt) {
380 clear();
381 if (this->capacity() < NumElts)
382 this->grow(NumElts);
383 this->setEnd(this->begin()+NumElts);
384 construct_range(this->begin(), this->end(), Elt);
385 }
386
erase(iterator I)387 iterator erase(iterator I) {
388 iterator N = I;
389 // Shift all elts down one.
390 std::copy(I+1, this->end(), I);
391 // Drop the last elt.
392 pop_back();
393 return(N);
394 }
395
erase(iterator S,iterator E)396 iterator erase(iterator S, iterator E) {
397 iterator N = S;
398 // Shift all elts down.
399 iterator I = std::copy(E, this->end(), S);
400 // Drop the last elts.
401 this->destroy_range(I, this->end());
402 this->setEnd(I);
403 return(N);
404 }
405
insert(iterator I,const T & Elt)406 iterator insert(iterator I, const T &Elt) {
407 if (I == this->end()) { // Important special case for empty vector.
408 push_back(Elt);
409 return this->end()-1;
410 }
411
412 if (this->EndX < this->CapacityX) {
413 Retry:
414 new (this->end()) T(this->back());
415 this->setEnd(this->end()+1);
416 // Push everything else over.
417 std::copy_backward(I, this->end()-1, this->end());
418 *I = Elt;
419 return I;
420 }
421 size_t EltNo = I-this->begin();
422 this->grow();
423 I = this->begin()+EltNo;
424 goto Retry;
425 }
426
insert(iterator I,size_type NumToInsert,const T & Elt)427 iterator insert(iterator I, size_type NumToInsert, const T &Elt) {
428 if (I == this->end()) { // Important special case for empty vector.
429 append(NumToInsert, Elt);
430 return this->end()-1;
431 }
432
433 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
434 size_t InsertElt = I - this->begin();
435
436 // Ensure there is enough space.
437 reserve(static_cast<unsigned>(this->size() + NumToInsert));
438
439 // Uninvalidate the iterator.
440 I = this->begin()+InsertElt;
441
442 // If there are more elements between the insertion point and the end of the
443 // range than there are being inserted, we can use a simple approach to
444 // insertion. Since we already reserved space, we know that this won't
445 // reallocate the vector.
446 if (size_t(this->end()-I) >= NumToInsert) {
447 T *OldEnd = this->end();
448 append(this->end()-NumToInsert, this->end());
449
450 // Copy the existing elements that get replaced.
451 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
452
453 std::fill_n(I, NumToInsert, Elt);
454 return I;
455 }
456
457 // Otherwise, we're inserting more elements than exist already, and we're
458 // not inserting at the end.
459
460 // Copy over the elements that we're about to overwrite.
461 T *OldEnd = this->end();
462 this->setEnd(this->end() + NumToInsert);
463 size_t NumOverwritten = OldEnd-I;
464 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
465
466 // Replace the overwritten part.
467 std::fill_n(I, NumOverwritten, Elt);
468
469 // Insert the non-overwritten middle part.
470 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt);
471 return I;
472 }
473
474 template<typename ItTy>
insert(iterator I,ItTy From,ItTy To)475 iterator insert(iterator I, ItTy From, ItTy To) {
476 if (I == this->end()) { // Important special case for empty vector.
477 append(From, To);
478 return this->end()-1;
479 }
480
481 size_t NumToInsert = std::distance(From, To);
482 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
483 size_t InsertElt = I - this->begin();
484
485 // Ensure there is enough space.
486 reserve(static_cast<unsigned>(this->size() + NumToInsert));
487
488 // Uninvalidate the iterator.
489 I = this->begin()+InsertElt;
490
491 // If there are more elements between the insertion point and the end of the
492 // range than there are being inserted, we can use a simple approach to
493 // insertion. Since we already reserved space, we know that this won't
494 // reallocate the vector.
495 if (size_t(this->end()-I) >= NumToInsert) {
496 T *OldEnd = this->end();
497 append(this->end()-NumToInsert, this->end());
498
499 // Copy the existing elements that get replaced.
500 std::copy_backward(I, OldEnd-NumToInsert, OldEnd);
501
502 std::copy(From, To, I);
503 return I;
504 }
505
506 // Otherwise, we're inserting more elements than exist already, and we're
507 // not inserting at the end.
508
509 // Copy over the elements that we're about to overwrite.
510 T *OldEnd = this->end();
511 this->setEnd(this->end() + NumToInsert);
512 size_t NumOverwritten = OldEnd-I;
513 this->uninitialized_copy(I, OldEnd, this->end()-NumOverwritten);
514
515 // Replace the overwritten part.
516 for (; NumOverwritten > 0; --NumOverwritten) {
517 *I = *From;
518 ++I; ++From;
519 }
520
521 // Insert the non-overwritten middle part.
522 this->uninitialized_copy(From, To, OldEnd);
523 return I;
524 }
525
526 const SmallVectorImpl
527 &operator=(const SmallVectorImpl &RHS);
528
529 bool operator==(const SmallVectorImpl &RHS) const {
530 if (this->size() != RHS.size()) return false;
531 return std::equal(this->begin(), this->end(), RHS.begin());
532 }
533 bool operator!=(const SmallVectorImpl &RHS) const {
534 return !(*this == RHS);
535 }
536
537 bool operator<(const SmallVectorImpl &RHS) const {
538 return std::lexicographical_compare(this->begin(), this->end(),
539 RHS.begin(), RHS.end());
540 }
541
542 /// set_size - Set the array size to \arg N, which the current array must have
543 /// enough capacity for.
544 ///
545 /// This does not construct or destroy any elements in the vector.
546 ///
547 /// Clients can use this in conjunction with capacity() to write past the end
548 /// of the buffer when they know that more elements are available, and only
549 /// update the size later. This avoids the cost of value initializing elements
550 /// which will only be overwritten.
set_size(unsigned N)551 void set_size(unsigned N) {
552 assert(N <= this->capacity());
553 this->setEnd(this->begin() + N);
554 }
555
556 private:
construct_range(T * S,T * E,const T & Elt)557 static void construct_range(T *S, T *E, const T &Elt) {
558 for (; S != E; ++S)
559 new (S) T(Elt);
560 }
561 };
562
563
564 template <typename T>
swap(SmallVectorImpl<T> & RHS)565 void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
566 if (this == &RHS) return;
567
568 // We can only avoid copying elements if neither vector is small.
569 if (!this->isSmall() && !RHS.isSmall()) {
570 std::swap(this->BeginX, RHS.BeginX);
571 std::swap(this->EndX, RHS.EndX);
572 std::swap(this->CapacityX, RHS.CapacityX);
573 return;
574 }
575 if (RHS.size() > this->capacity())
576 this->grow(RHS.size());
577 if (this->size() > RHS.capacity())
578 RHS.grow(this->size());
579
580 // Swap the shared elements.
581 size_t NumShared = this->size();
582 if (NumShared > RHS.size()) NumShared = RHS.size();
583 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i)
584 std::swap((*this)[i], RHS[i]);
585
586 // Copy over the extra elts.
587 if (this->size() > RHS.size()) {
588 size_t EltDiff = this->size() - RHS.size();
589 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
590 RHS.setEnd(RHS.end()+EltDiff);
591 this->destroy_range(this->begin()+NumShared, this->end());
592 this->setEnd(this->begin()+NumShared);
593 } else if (RHS.size() > this->size()) {
594 size_t EltDiff = RHS.size() - this->size();
595 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
596 this->setEnd(this->end() + EltDiff);
597 this->destroy_range(RHS.begin()+NumShared, RHS.end());
598 RHS.setEnd(RHS.begin()+NumShared);
599 }
600 }
601
602 template <typename T>
603 const SmallVectorImpl<T> &SmallVectorImpl<T>::
604 operator=(const SmallVectorImpl<T> &RHS) {
605 // Avoid self-assignment.
606 if (this == &RHS) return *this;
607
608 // If we already have sufficient space, assign the common elements, then
609 // destroy any excess.
610 size_t RHSSize = RHS.size();
611 size_t CurSize = this->size();
612 if (CurSize >= RHSSize) {
613 // Assign common elements.
614 iterator NewEnd;
615 if (RHSSize)
616 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
617 else
618 NewEnd = this->begin();
619
620 // Destroy excess elements.
621 this->destroy_range(NewEnd, this->end());
622
623 // Trim.
624 this->setEnd(NewEnd);
625 return *this;
626 }
627
628 // If we have to grow to have enough elements, destroy the current elements.
629 // This allows us to avoid copying them during the grow.
630 if (this->capacity() < RHSSize) {
631 // Destroy current elements.
632 this->destroy_range(this->begin(), this->end());
633 this->setEnd(this->begin());
634 CurSize = 0;
635 this->grow(RHSSize);
636 } else if (CurSize) {
637 // Otherwise, use assignment for the already-constructed elements.
638 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
639 }
640
641 // Copy construct the new elements in place.
642 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
643 this->begin()+CurSize);
644
645 // Set end.
646 this->setEnd(this->begin()+RHSSize);
647 return *this;
648 }
649
650
651 /// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
652 /// for the case when the array is small. It contains some number of elements
653 /// in-place, which allows it to avoid heap allocation when the actual number of
654 /// elements is below that threshold. This allows normal "small" cases to be
655 /// fast without losing generality for large inputs.
656 ///
657 /// Note that this does not attempt to be exception safe.
658 ///
659 template <typename T, unsigned N>
660 class SmallVector : public SmallVectorImpl<T> {
661 /// InlineElts - These are 'N-1' elements that are stored inline in the body
662 /// of the vector. The extra '1' element is stored in SmallVectorImpl.
663 typedef typename SmallVectorImpl<T>::U U;
664 enum {
665 // MinUs - The number of U's require to cover N T's.
666 MinUs = (static_cast<unsigned int>(sizeof(T))*N +
667 static_cast<unsigned int>(sizeof(U)) - 1) /
668 static_cast<unsigned int>(sizeof(U)),
669
670 // NumInlineEltsElts - The number of elements actually in this array. There
671 // is already one in the parent class, and we have to round up to avoid
672 // having a zero-element array.
673 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1,
674
675 // NumTsAvailable - The number of T's we actually have space for, which may
676 // be more than N due to rounding.
677 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/
678 static_cast<unsigned int>(sizeof(T))
679 };
680 U InlineElts[NumInlineEltsElts];
681 public:
SmallVector()682 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
683 }
684
685 explicit SmallVector(unsigned Size, const T &Value = T())
686 : SmallVectorImpl<T>(NumTsAvailable) {
687 this->reserve(Size);
688 while (Size--)
689 this->push_back(Value);
690 }
691
692 template<typename ItTy>
SmallVector(ItTy S,ItTy E)693 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
694 this->append(S, E);
695 }
696
SmallVector(const SmallVector & RHS)697 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
698 if (!RHS.empty())
699 SmallVectorImpl<T>::operator=(RHS);
700 }
701
702 const SmallVector &operator=(const SmallVector &RHS) {
703 SmallVectorImpl<T>::operator=(RHS);
704 return *this;
705 }
706
707 };
708
709 /// Specialize SmallVector at N=0. This specialization guarantees
710 /// that it can be instantiated at an incomplete T if none of its
711 /// members are required.
712 template <typename T>
713 class SmallVector<T,0> : public SmallVectorImpl<T> {
714 public:
SmallVector()715 SmallVector() : SmallVectorImpl<T>(0) {}
716
717 explicit SmallVector(unsigned Size, const T &Value = T())
718 : SmallVectorImpl<T>(0) {
719 this->reserve(Size);
720 while (Size--)
721 this->push_back(Value);
722 }
723
724 template<typename ItTy>
SmallVector(ItTy S,ItTy E)725 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(0) {
726 this->append(S, E);
727 }
728
SmallVector(const SmallVector & RHS)729 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(0) {
730 SmallVectorImpl<T>::operator=(RHS);
731 }
732
733 SmallVector &operator=(const SmallVectorImpl<T> &RHS) {
734 return SmallVectorImpl<T>::operator=(RHS);
735 }
736
737 };
738
739 } // End llvm namespace
740
741 namespace std {
742 /// Implement std::swap in terms of SmallVector swap.
743 template<typename T>
744 inline void
swap(llvm::SmallVectorImpl<T> & LHS,llvm::SmallVectorImpl<T> & RHS)745 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
746 LHS.swap(RHS);
747 }
748
749 /// Implement std::swap in terms of SmallVector swap.
750 template<typename T, unsigned N>
751 inline void
swap(llvm::SmallVector<T,N> & LHS,llvm::SmallVector<T,N> & RHS)752 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {
753 LHS.swap(RHS);
754 }
755 }
756
757 #endif
758