SmallVector.h revision dae2206390be0b1886cf0c1dba3edf079d28274f
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/ADT/iterator.h" 18#include "llvm/Support/type_traits.h" 19#include <algorithm> 20#include <cassert> 21#include <cstring> 22#include <memory> 23 24#ifdef _MSC_VER 25namespace std { 26#if _MSC_VER <= 1310 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; 33 return _Cat; 34 } 35 36 template<class T1, class T2> 37 inline _Scalar_ptr_iterator_tag _Ptr_cat(T1* const *, T2 **) { 38 _Scalar_ptr_iterator_tag _Cat; 39 return _Cat; 40 } 41#else 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. 44#endif 45} 46#endif 47 48namespace llvm { 49 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. 53template <typename T> 54class SmallVectorImpl { 55protected: 56 T *Begin, *End, *Capacity; 57 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. 63protected: 64#ifdef __GNUC__ 65 typedef char U; 66 U FirstEl __attribute__((aligned)); 67#else 68 union U { 69 double D; 70 long double LD; 71 long long L; 72 void *P; 73 } FirstEl; 74#endif 75 // Space after 'FirstEl' is clobbered, do not add any instance vars after it. 76public: 77 // Default ctor - Initialize to empty. 78 explicit SmallVectorImpl(unsigned N) 79 : Begin(reinterpret_cast<T*>(&FirstEl)), 80 End(reinterpret_cast<T*>(&FirstEl)), 81 Capacity(reinterpret_cast<T*>(&FirstEl)+N) { 82 } 83 84 ~SmallVectorImpl() { 85 // Destroy the constructed elements in the vector. 86 destroy_range(Begin, End); 87 88 // If this wasn't grown from the inline copy, deallocate the old space. 89 if (!isSmall()) 90 operator delete(Begin); 91 } 92 93 typedef size_t size_type; 94 typedef ptrdiff_t difference_type; 95 typedef T value_type; 96 typedef T* iterator; 97 typedef const T* const_iterator; 98 99 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 100 typedef std::reverse_iterator<iterator> reverse_iterator; 101 102 typedef T& reference; 103 typedef const T& const_reference; 104 typedef T* pointer; 105 typedef const T* const_pointer; 106 107 bool empty() const { return Begin == End; } 108 size_type size() const { return End-Begin; } 109 size_type max_size() const { return size_type(-1) / sizeof(T); } 110 111 // forward iterator creation methods. 112 iterator begin() { return Begin; } 113 const_iterator begin() const { return Begin; } 114 iterator end() { return End; } 115 const_iterator end() const { return End; } 116 117 // reverse iterator creation methods. 118 reverse_iterator rbegin() { return reverse_iterator(end()); } 119 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); } 120 reverse_iterator rend() { return reverse_iterator(begin()); } 121 const_reverse_iterator rend() const { return const_reverse_iterator(begin());} 122 123 124 /* These asserts could be "Begin + idx < End", but there are lots of places 125 in llvm where we use &v[v.size()] instead of v.end(). */ 126 reference operator[](unsigned idx) { 127 assert (Begin + idx <= End); 128 return Begin[idx]; 129 } 130 const_reference operator[](unsigned idx) const { 131 assert (Begin + idx <= End); 132 return Begin[idx]; 133 } 134 135 reference front() { 136 return begin()[0]; 137 } 138 const_reference front() const { 139 return begin()[0]; 140 } 141 142 reference back() { 143 return end()[-1]; 144 } 145 const_reference back() const { 146 return end()[-1]; 147 } 148 149 void push_back(const_reference Elt) { 150 if (End < Capacity) { 151 Retry: 152 new (End) T(Elt); 153 ++End; 154 return; 155 } 156 grow(); 157 goto Retry; 158 } 159 160 void pop_back() { 161 --End; 162 End->~T(); 163 } 164 165 T pop_back_val() { 166 T Result = back(); 167 pop_back(); 168 return Result; 169 } 170 171 void clear() { 172 destroy_range(Begin, End); 173 End = Begin; 174 } 175 176 void resize(unsigned N) { 177 if (N < size()) { 178 destroy_range(Begin+N, End); 179 End = Begin+N; 180 } else if (N > size()) { 181 if (unsigned(Capacity-Begin) < N) 182 grow(N); 183 construct_range(End, Begin+N, T()); 184 End = Begin+N; 185 } 186 } 187 188 void resize(unsigned N, const T &NV) { 189 if (N < size()) { 190 destroy_range(Begin+N, End); 191 End = Begin+N; 192 } else if (N > size()) { 193 if (unsigned(Capacity-Begin) < N) 194 grow(N); 195 construct_range(End, Begin+N, NV); 196 End = Begin+N; 197 } 198 } 199 200 void reserve(unsigned N) { 201 if (unsigned(Capacity-Begin) < N) 202 grow(N); 203 } 204 205 void swap(SmallVectorImpl &RHS); 206 207 /// append - Add the specified range to the end of the SmallVector. 208 /// 209 template<typename in_iter> 210 void append(in_iter in_start, in_iter in_end) { 211 size_type NumInputs = std::distance(in_start, in_end); 212 // Grow allocated space if needed. 213 if (End+NumInputs > Capacity) 214 grow(size()+NumInputs); 215 216 // Copy the new elements over. 217 std::uninitialized_copy(in_start, in_end, End); 218 End += NumInputs; 219 } 220 221 /// append - Add the specified range to the end of the SmallVector. 222 /// 223 void append(size_type NumInputs, const T &Elt) { 224 // Grow allocated space if needed. 225 if (End+NumInputs > Capacity) 226 grow(size()+NumInputs); 227 228 // Copy the new elements over. 229 std::uninitialized_fill_n(End, NumInputs, Elt); 230 End += NumInputs; 231 } 232 233 void assign(unsigned NumElts, const T &Elt) { 234 clear(); 235 if (unsigned(Capacity-Begin) < NumElts) 236 grow(NumElts); 237 End = Begin+NumElts; 238 construct_range(Begin, End, Elt); 239 } 240 241 iterator erase(iterator I) { 242 iterator N = I; 243 // Shift all elts down one. 244 std::copy(I+1, End, I); 245 // Drop the last elt. 246 pop_back(); 247 return(N); 248 } 249 250 iterator erase(iterator S, iterator E) { 251 iterator N = S; 252 // Shift all elts down. 253 iterator I = std::copy(E, End, S); 254 // Drop the last elts. 255 destroy_range(I, End); 256 End = I; 257 return(N); 258 } 259 260 iterator insert(iterator I, const T &Elt) { 261 if (I == End) { // Important special case for empty vector. 262 push_back(Elt); 263 return end()-1; 264 } 265 266 if (End < Capacity) { 267 Retry: 268 new (End) T(back()); 269 ++End; 270 // Push everything else over. 271 std::copy_backward(I, End-1, End); 272 *I = Elt; 273 return I; 274 } 275 size_t EltNo = I-Begin; 276 grow(); 277 I = Begin+EltNo; 278 goto Retry; 279 } 280 281 iterator insert(iterator I, size_type NumToInsert, const T &Elt) { 282 if (I == End) { // Important special case for empty vector. 283 append(NumToInsert, Elt); 284 return end()-1; 285 } 286 287 // Convert iterator to elt# to avoid invalidating iterator when we reserve() 288 size_t InsertElt = I-begin(); 289 290 // Ensure there is enough space. 291 reserve(static_cast<unsigned>(size() + NumToInsert)); 292 293 // Uninvalidate the iterator. 294 I = begin()+InsertElt; 295 296 // If there are more elements between the insertion point and the end of the 297 // range than there are being inserted, we can use a simple approach to 298 // insertion. Since we already reserved space, we know that this won't 299 // reallocate the vector. 300 if (size_t(end()-I) >= NumToInsert) { 301 T *OldEnd = End; 302 append(End-NumToInsert, End); 303 304 // Copy the existing elements that get replaced. 305 std::copy(I, OldEnd-NumToInsert, I+NumToInsert); 306 307 std::fill_n(I, NumToInsert, Elt); 308 return I; 309 } 310 311 // Otherwise, we're inserting more elements than exist already, and we're 312 // not inserting at the end. 313 314 // Copy over the elements that we're about to overwrite. 315 T *OldEnd = End; 316 End += NumToInsert; 317 size_t NumOverwritten = OldEnd-I; 318 std::uninitialized_copy(I, OldEnd, End-NumOverwritten); 319 320 // Replace the overwritten part. 321 std::fill_n(I, NumOverwritten, Elt); 322 323 // Insert the non-overwritten middle part. 324 std::uninitialized_fill_n(OldEnd, NumToInsert-NumOverwritten, Elt); 325 return I; 326 } 327 328 template<typename ItTy> 329 iterator insert(iterator I, ItTy From, ItTy To) { 330 if (I == End) { // Important special case for empty vector. 331 append(From, To); 332 return end()-1; 333 } 334 335 size_t NumToInsert = std::distance(From, To); 336 // Convert iterator to elt# to avoid invalidating iterator when we reserve() 337 size_t InsertElt = I-begin(); 338 339 // Ensure there is enough space. 340 reserve(static_cast<unsigned>(size() + NumToInsert)); 341 342 // Uninvalidate the iterator. 343 I = begin()+InsertElt; 344 345 // If there are more elements between the insertion point and the end of the 346 // range than there are being inserted, we can use a simple approach to 347 // insertion. Since we already reserved space, we know that this won't 348 // reallocate the vector. 349 if (size_t(end()-I) >= NumToInsert) { 350 T *OldEnd = End; 351 append(End-NumToInsert, End); 352 353 // Copy the existing elements that get replaced. 354 std::copy(I, OldEnd-NumToInsert, I+NumToInsert); 355 356 std::copy(From, To, I); 357 return I; 358 } 359 360 // Otherwise, we're inserting more elements than exist already, and we're 361 // not inserting at the end. 362 363 // Copy over the elements that we're about to overwrite. 364 T *OldEnd = End; 365 End += NumToInsert; 366 size_t NumOverwritten = OldEnd-I; 367 std::uninitialized_copy(I, OldEnd, End-NumOverwritten); 368 369 // Replace the overwritten part. 370 std::copy(From, From+NumOverwritten, I); 371 372 // Insert the non-overwritten middle part. 373 std::uninitialized_copy(From+NumOverwritten, To, OldEnd); 374 return I; 375 } 376 377 const SmallVectorImpl &operator=(const SmallVectorImpl &RHS); 378 379 bool operator==(const SmallVectorImpl &RHS) const { 380 if (size() != RHS.size()) return false; 381 for (T *This = Begin, *That = RHS.Begin, *E = Begin+size(); 382 This != E; ++This, ++That) 383 if (*This != *That) 384 return false; 385 return true; 386 } 387 bool operator!=(const SmallVectorImpl &RHS) const { return !(*this == RHS); } 388 389 bool operator<(const SmallVectorImpl &RHS) const { 390 return std::lexicographical_compare(begin(), end(), 391 RHS.begin(), RHS.end()); 392 } 393 394private: 395 /// isSmall - Return true if this is a smallvector which has not had dynamic 396 /// memory allocated for it. 397 bool isSmall() const { 398 return static_cast<const void*>(Begin) == 399 static_cast<const void*>(&FirstEl); 400 } 401 402 /// grow - double the size of the allocated memory, guaranteeing space for at 403 /// least one more element or MinSize if specified. 404 void grow(size_type MinSize = 0); 405 406 void construct_range(T *S, T *E, const T &Elt) { 407 for (; S != E; ++S) 408 new (S) T(Elt); 409 } 410 411 void destroy_range(T *S, T *E) { 412 while (S != E) { 413 --E; 414 E->~T(); 415 } 416 } 417}; 418 419// Define this out-of-line to dissuade the C++ compiler from inlining it. 420template <typename T> 421void SmallVectorImpl<T>::grow(size_t MinSize) { 422 size_t CurCapacity = Capacity-Begin; 423 size_t CurSize = size(); 424 size_t NewCapacity = 2*CurCapacity; 425 if (NewCapacity < MinSize) 426 NewCapacity = MinSize; 427 T *NewElts = static_cast<T*>(operator new(NewCapacity*sizeof(T))); 428 429 // Copy the elements over. 430 if (is_class<T>::value) 431 std::uninitialized_copy(Begin, End, NewElts); 432 else 433 // Use memcpy for PODs (std::uninitialized_copy optimizes to memmove). 434 memcpy(NewElts, Begin, CurSize * sizeof(T)); 435 436 // Destroy the original elements. 437 destroy_range(Begin, End); 438 439 // If this wasn't grown from the inline copy, deallocate the old space. 440 if (!isSmall()) 441 operator delete(Begin); 442 443 Begin = NewElts; 444 End = NewElts+CurSize; 445 Capacity = Begin+NewCapacity; 446} 447 448template <typename T> 449void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) { 450 if (this == &RHS) return; 451 452 // We can only avoid copying elements if neither vector is small. 453 if (!isSmall() && !RHS.isSmall()) { 454 std::swap(Begin, RHS.Begin); 455 std::swap(End, RHS.End); 456 std::swap(Capacity, RHS.Capacity); 457 return; 458 } 459 if (Begin+RHS.size() > Capacity) 460 grow(RHS.size()); 461 if (RHS.begin()+size() > RHS.Capacity) 462 RHS.grow(size()); 463 464 // Swap the shared elements. 465 size_t NumShared = size(); 466 if (NumShared > RHS.size()) NumShared = RHS.size(); 467 for (unsigned i = 0; i != static_cast<unsigned>(NumShared); ++i) 468 std::swap(Begin[i], RHS[i]); 469 470 // Copy over the extra elts. 471 if (size() > RHS.size()) { 472 size_t EltDiff = size() - RHS.size(); 473 std::uninitialized_copy(Begin+NumShared, End, RHS.End); 474 RHS.End += EltDiff; 475 destroy_range(Begin+NumShared, End); 476 End = Begin+NumShared; 477 } else if (RHS.size() > size()) { 478 size_t EltDiff = RHS.size() - size(); 479 std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End); 480 End += EltDiff; 481 destroy_range(RHS.Begin+NumShared, RHS.End); 482 RHS.End = RHS.Begin+NumShared; 483 } 484} 485 486template <typename T> 487const SmallVectorImpl<T> & 488SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) { 489 // Avoid self-assignment. 490 if (this == &RHS) return *this; 491 492 // If we already have sufficient space, assign the common elements, then 493 // destroy any excess. 494 unsigned RHSSize = unsigned(RHS.size()); 495 unsigned CurSize = unsigned(size()); 496 if (CurSize >= RHSSize) { 497 // Assign common elements. 498 iterator NewEnd; 499 if (RHSSize) 500 NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin); 501 else 502 NewEnd = Begin; 503 504 // Destroy excess elements. 505 destroy_range(NewEnd, End); 506 507 // Trim. 508 End = NewEnd; 509 return *this; 510 } 511 512 // If we have to grow to have enough elements, destroy the current elements. 513 // This allows us to avoid copying them during the grow. 514 if (unsigned(Capacity-Begin) < RHSSize) { 515 // Destroy current elements. 516 destroy_range(Begin, End); 517 End = Begin; 518 CurSize = 0; 519 grow(RHSSize); 520 } else if (CurSize) { 521 // Otherwise, use assignment for the already-constructed elements. 522 std::copy(RHS.Begin, RHS.Begin+CurSize, Begin); 523 } 524 525 // Copy construct the new elements in place. 526 std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize); 527 528 // Set end. 529 End = Begin+RHSSize; 530 return *this; 531} 532 533/// SmallVector - This is a 'vector' (really, a variable-sized array), optimized 534/// for the case when the array is small. It contains some number of elements 535/// in-place, which allows it to avoid heap allocation when the actual number of 536/// elements is below that threshold. This allows normal "small" cases to be 537/// fast without losing generality for large inputs. 538/// 539/// Note that this does not attempt to be exception safe. 540/// 541template <typename T, unsigned N> 542class SmallVector : public SmallVectorImpl<T> { 543 /// InlineElts - These are 'N-1' elements that are stored inline in the body 544 /// of the vector. The extra '1' element is stored in SmallVectorImpl. 545 typedef typename SmallVectorImpl<T>::U U; 546 enum { 547 // MinUs - The number of U's require to cover N T's. 548 MinUs = (static_cast<unsigned int>(sizeof(T))*N + 549 static_cast<unsigned int>(sizeof(U)) - 1) / 550 static_cast<unsigned int>(sizeof(U)), 551 552 // NumInlineEltsElts - The number of elements actually in this array. There 553 // is already one in the parent class, and we have to round up to avoid 554 // having a zero-element array. 555 NumInlineEltsElts = MinUs > 1 ? (MinUs - 1) : 1, 556 557 // NumTsAvailable - The number of T's we actually have space for, which may 558 // be more than N due to rounding. 559 NumTsAvailable = (NumInlineEltsElts+1)*static_cast<unsigned int>(sizeof(U))/ 560 static_cast<unsigned int>(sizeof(T)) 561 }; 562 U InlineElts[NumInlineEltsElts]; 563public: 564 SmallVector() : SmallVectorImpl<T>(NumTsAvailable) { 565 } 566 567 explicit SmallVector(unsigned Size, const T &Value = T()) 568 : SmallVectorImpl<T>(NumTsAvailable) { 569 this->reserve(Size); 570 while (Size--) 571 this->push_back(Value); 572 } 573 574 template<typename ItTy> 575 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) { 576 this->append(S, E); 577 } 578 579 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) { 580 if (!RHS.empty()) 581 SmallVectorImpl<T>::operator=(RHS); 582 } 583 584 const SmallVector &operator=(const SmallVector &RHS) { 585 SmallVectorImpl<T>::operator=(RHS); 586 return *this; 587 } 588 589}; 590 591} // End llvm namespace 592 593namespace std { 594 /// Implement std::swap in terms of SmallVector swap. 595 template<typename T> 596 inline void 597 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) { 598 LHS.swap(RHS); 599 } 600 601 /// Implement std::swap in terms of SmallVector swap. 602 template<typename T, unsigned N> 603 inline void 604 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) { 605 LHS.swap(RHS); 606 } 607} 608 609#endif 610