1//===- ArrayRef.h - Array Reference Wrapper ---------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_ADT_ARRAYREF_H
10#define LLVM_ADT_ARRAYREF_H
11
12#include "llvm/ADT/Hashing.h"
13#include "llvm/ADT/None.h"
14#include "llvm/ADT/SmallVector.h"
15#include "llvm/ADT/STLExtras.h"
16#include "llvm/Support/Compiler.h"
17#include <algorithm>
18#include <array>
19#include <cassert>
20#include <cstddef>
21#include <initializer_list>
22#include <iterator>
23#include <memory>
24#include <type_traits>
25#include <vector>
26
27namespace llvm {
28
29 /// ArrayRef - Represent a constant reference to an array (0 or more elements
30 /// consecutively in memory), i.e. a start pointer and a length. It allows
31 /// various APIs to take consecutive elements easily and conveniently.
32 ///
33 /// This class does not own the underlying data, it is expected to be used in
34 /// situations where the data resides in some other buffer, whose lifetime
35 /// extends past that of the ArrayRef. For this reason, it is not in general
36 /// safe to store an ArrayRef.
37 ///
38 /// This is intended to be trivially copyable, so it should be passed by
39 /// value.
40 template<typename T>
41 class LLVM_NODISCARD ArrayRef {
42 public:
43 using iterator = const T *;
44 using const_iterator = const T *;
45 using size_type = size_t;
46 using reverse_iterator = std::reverse_iterator<iterator>;
47
48 private:
49 /// The start of the array, in an external buffer.
50 const T *Data = nullptr;
51
52 /// The number of elements.
53 size_type Length = 0;
54
55 public:
56 /// @name Constructors
57 /// @{
58
59 /// Construct an empty ArrayRef.
60 /*implicit*/ ArrayRef() = default;
61
62 /// Construct an empty ArrayRef from None.
63 /*implicit*/ ArrayRef(NoneType) {}
64
65 /// Construct an ArrayRef from a single element.
66 /*implicit*/ ArrayRef(const T &OneElt)
67 : Data(&OneElt), Length(1) {}
68
69 /// Construct an ArrayRef from a pointer and length.
70 /*implicit*/ ArrayRef(const T *data, size_t length)
71 : Data(data), Length(length) {}
72
73 /// Construct an ArrayRef from a range.
74 ArrayRef(const T *begin, const T *end)
75 : Data(begin), Length(end - begin) {}
76
77 /// Construct an ArrayRef from a SmallVector. This is templated in order to
78 /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
79 /// copy-construct an ArrayRef.
80 template<typename U>
81 /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
82 : Data(Vec.data()), Length(Vec.size()) {
83 }
84
85 /// Construct an ArrayRef from a std::vector.
86 template<typename A>
87 /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
88 : Data(Vec.data()), Length(Vec.size()) {}
89
90 /// Construct an ArrayRef from a std::array
91 template <size_t N>
92 /*implicit*/ constexpr ArrayRef(const std::array<T, N> &Arr)
93 : Data(Arr.data()), Length(N) {}
94
95 /// Construct an ArrayRef from a C array.
96 template <size_t N>
97 /*implicit*/ constexpr ArrayRef(const T (&Arr)[N]) : Data(Arr), Length(N) {}
98
99 /// Construct an ArrayRef from a std::initializer_list.
100 /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
101 : Data(Vec.begin() == Vec.end() ? (T*)nullptr : Vec.begin()),
102 Length(Vec.size()) {}
103
104 /// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to
105 /// ensure that only ArrayRefs of pointers can be converted.
106 template <typename U>
107 ArrayRef(
108 const ArrayRef<U *> &A,
109 typename std::enable_if<
110 std::is_convertible<U *const *, T const *>::value>::type * = nullptr)
111 : Data(A.data()), Length(A.size()) {}
112
113 /// Construct an ArrayRef<const T*> from a SmallVector<T*>. This is
114 /// templated in order to avoid instantiating SmallVectorTemplateCommon<T>
115 /// whenever we copy-construct an ArrayRef.
116 template<typename U, typename DummyT>
117 /*implicit*/ ArrayRef(
118 const SmallVectorTemplateCommon<U *, DummyT> &Vec,
119 typename std::enable_if<
120 std::is_convertible<U *const *, T const *>::value>::type * = nullptr)
121 : Data(Vec.data()), Length(Vec.size()) {
122 }
123
124 /// Construct an ArrayRef<const T*> from std::vector<T*>. This uses SFINAE
125 /// to ensure that only vectors of pointers can be converted.
126 template<typename U, typename A>
127 ArrayRef(const std::vector<U *, A> &Vec,
128 typename std::enable_if<
129 std::is_convertible<U *const *, T const *>::value>::type* = 0)
130 : Data(Vec.data()), Length(Vec.size()) {}
131
132 /// @}
133 /// @name Simple Operations
134 /// @{
135
136 iterator begin() const { return Data; }
137 iterator end() const { return Data + Length; }
138
139 reverse_iterator rbegin() const { return reverse_iterator(end()); }
140 reverse_iterator rend() const { return reverse_iterator(begin()); }
141
142 /// empty - Check if the array is empty.
143 bool empty() const { return Length == 0; }
144
145 const T *data() const { return Data; }
146
147 /// size - Get the array size.
148 size_t size() const { return Length; }
149
150 /// front - Get the first element.
151 const T &front() const {
152 assert(!empty());
153 return Data[0];
154 }
155
156 /// back - Get the last element.
157 const T &back() const {
158 assert(!empty());
159 return Data[Length-1];
160 }
161
162 // copy - Allocate copy in Allocator and return ArrayRef<T> to it.
163 template <typename Allocator> ArrayRef<T> copy(Allocator &A) {
164 T *Buff = A.template Allocate<T>(Length);
165 std::uninitialized_copy(begin(), end(), Buff);
166 return ArrayRef<T>(Buff, Length);
167 }
168
169 /// equals - Check for element-wise equality.
170 bool equals(ArrayRef RHS) const {
171 if (Length != RHS.Length)
172 return false;
173 return std::equal(begin(), end(), RHS.begin());
174 }
175
176 /// slice(n, m) - Chop off the first N elements of the array, and keep M
177 /// elements in the array.
178 ArrayRef<T> slice(size_t N, size_t M) const {
179 assert(N+M <= size() && "Invalid specifier");
180 return ArrayRef<T>(data()+N, M);
181 }
182
183 /// slice(n) - Chop off the first N elements of the array.
184 ArrayRef<T> slice(size_t N) const { return slice(N, size() - N); }
185
186 /// Drop the first \p N elements of the array.
187 ArrayRef<T> drop_front(size_t N = 1) const {
188 assert(size() >= N && "Dropping more elements than exist");
189 return slice(N, size() - N);
190 }
191
192 /// Drop the last \p N elements of the array.
193 ArrayRef<T> drop_back(size_t N = 1) const {
194 assert(size() >= N && "Dropping more elements than exist");
195 return slice(0, size() - N);
196 }
197
198 /// Return a copy of *this with the first N elements satisfying the
199 /// given predicate removed.
200 template <class PredicateT> ArrayRef<T> drop_while(PredicateT Pred) const {
201 return ArrayRef<T>(find_if_not(*this, Pred), end());
202 }
203
204 /// Return a copy of *this with the first N elements not satisfying
205 /// the given predicate removed.
206 template <class PredicateT> ArrayRef<T> drop_until(PredicateT Pred) const {
207 return ArrayRef<T>(find_if(*this, Pred), end());
208 }
209
210 /// Return a copy of *this with only the first \p N elements.
211 ArrayRef<T> take_front(size_t N = 1) const {
212 if (N >= size())
213 return *this;
214 return drop_back(size() - N);
215 }
216
217 /// Return a copy of *this with only the last \p N elements.
218 ArrayRef<T> take_back(size_t N = 1) const {
219 if (N >= size())
220 return *this;
221 return drop_front(size() - N);
222 }
223
224 /// Return the first N elements of this Array that satisfy the given
225 /// predicate.
226 template <class PredicateT> ArrayRef<T> take_while(PredicateT Pred) const {
227 return ArrayRef<T>(begin(), find_if_not(*this, Pred));
228 }
229
230 /// Return the first N elements of this Array that don't satisfy the
231 /// given predicate.
232 template <class PredicateT> ArrayRef<T> take_until(PredicateT Pred) const {
233 return ArrayRef<T>(begin(), find_if(*this, Pred));
234 }
235
236 /// @}
237 /// @name Operator Overloads
238 /// @{
239 const T &operator[](size_t Index) const {
240 assert(Index < Length && "Invalid index!");
241 return Data[Index];
242 }
243
244 /// Disallow accidental assignment from a temporary.
245 ///
246 /// The declaration here is extra complicated so that "arrayRef = {}"
247 /// continues to select the move assignment operator.
248 template <typename U>
249 typename std::enable_if<std::is_same<U, T>::value, ArrayRef<T>>::type &
250 operator=(U &&Temporary) = delete;
251
252 /// Disallow accidental assignment from a temporary.
253 ///
254 /// The declaration here is extra complicated so that "arrayRef = {}"
255 /// continues to select the move assignment operator.
256 template <typename U>
257 typename std::enable_if<std::is_same<U, T>::value, ArrayRef<T>>::type &
258 operator=(std::initializer_list<U>) = delete;
259
260 /// @}
261 /// @name Expensive Operations
262 /// @{
263 std::vector<T> vec() const {
264 return std::vector<T>(Data, Data+Length);
265 }
266
267 /// @}
268 /// @name Conversion operators
269 /// @{
270 operator std::vector<T>() const {
271 return std::vector<T>(Data, Data+Length);
272 }
273
274 /// @}
275 };
276
277 /// MutableArrayRef - Represent a mutable reference to an array (0 or more
278 /// elements consecutively in memory), i.e. a start pointer and a length. It
279 /// allows various APIs to take and modify consecutive elements easily and
280 /// conveniently.
281 ///
282 /// This class does not own the underlying data, it is expected to be used in
283 /// situations where the data resides in some other buffer, whose lifetime
284 /// extends past that of the MutableArrayRef. For this reason, it is not in
285 /// general safe to store a MutableArrayRef.
286 ///
287 /// This is intended to be trivially copyable, so it should be passed by
288 /// value.
289 template<typename T>
290 class LLVM_NODISCARD MutableArrayRef : public ArrayRef<T> {
291 public:
292 using iterator = T *;
293 using reverse_iterator = std::reverse_iterator<iterator>;
294
295 /// Construct an empty MutableArrayRef.
296 /*implicit*/ MutableArrayRef() = default;
297
298 /// Construct an empty MutableArrayRef from None.
299 /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
300
301 /// Construct an MutableArrayRef from a single element.
302 /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
303
304 /// Construct an MutableArrayRef from a pointer and length.
305 /*implicit*/ MutableArrayRef(T *data, size_t length)
306 : ArrayRef<T>(data, length) {}
307
308 /// Construct an MutableArrayRef from a range.
309 MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
310
311 /// Construct an MutableArrayRef from a SmallVector.
312 /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
313 : ArrayRef<T>(Vec) {}
314
315 /// Construct a MutableArrayRef from a std::vector.
316 /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
317 : ArrayRef<T>(Vec) {}
318
319 /// Construct an ArrayRef from a std::array
320 template <size_t N>
321 /*implicit*/ constexpr MutableArrayRef(std::array<T, N> &Arr)
322 : ArrayRef<T>(Arr) {}
323
324 /// Construct an MutableArrayRef from a C array.
325 template <size_t N>
326 /*implicit*/ constexpr MutableArrayRef(T (&Arr)[N]) : ArrayRef<T>(Arr) {}
327
328 T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
329
330 iterator begin() const { return data(); }
331 iterator end() const { return data() + this->size(); }
332
333 reverse_iterator rbegin() const { return reverse_iterator(end()); }
334 reverse_iterator rend() const { return reverse_iterator(begin()); }
335
336 /// front - Get the first element.
337 T &front() const {
338 assert(!this->empty());
339 return data()[0];
340 }
341
342 /// back - Get the last element.
343 T &back() const {
344 assert(!this->empty());
345 return data()[this->size()-1];
346 }
347
348 /// slice(n, m) - Chop off the first N elements of the array, and keep M
349 /// elements in the array.
350 MutableArrayRef<T> slice(size_t N, size_t M) const {
351 assert(N + M <= this->size() && "Invalid specifier");
352 return MutableArrayRef<T>(this->data() + N, M);
353 }
354
355 /// slice(n) - Chop off the first N elements of the array.
356 MutableArrayRef<T> slice(size_t N) const {
357 return slice(N, this->size() - N);
358 }
359
360 /// Drop the first \p N elements of the array.
361 MutableArrayRef<T> drop_front(size_t N = 1) const {
362 assert(this->size() >= N && "Dropping more elements than exist");
363 return slice(N, this->size() - N);
364 }
365
366 MutableArrayRef<T> drop_back(size_t N = 1) const {
367 assert(this->size() >= N && "Dropping more elements than exist");
368 return slice(0, this->size() - N);
369 }
370
371 /// Return a copy of *this with the first N elements satisfying the
372 /// given predicate removed.
373 template <class PredicateT>
374 MutableArrayRef<T> drop_while(PredicateT Pred) const {
375 return MutableArrayRef<T>(find_if_not(*this, Pred), end());
376 }
377
378 /// Return a copy of *this with the first N elements not satisfying
379 /// the given predicate removed.
380 template <class PredicateT>
381 MutableArrayRef<T> drop_until(PredicateT Pred) const {
382 return MutableArrayRef<T>(find_if(*this, Pred), end());
383 }
384
385 /// Return a copy of *this with only the first \p N elements.
386 MutableArrayRef<T> take_front(size_t N = 1) const {
387 if (N >= this->size())
388 return *this;
389 return drop_back(this->size() - N);
390 }
391
392 /// Return a copy of *this with only the last \p N elements.
393 MutableArrayRef<T> take_back(size_t N = 1) const {
394 if (N >= this->size())
395 return *this;
396 return drop_front(this->size() - N);
397 }
398
399 /// Return the first N elements of this Array that satisfy the given
400 /// predicate.
401 template <class PredicateT>
402 MutableArrayRef<T> take_while(PredicateT Pred) const {
403 return MutableArrayRef<T>(begin(), find_if_not(*this, Pred));
404 }
405
406 /// Return the first N elements of this Array that don't satisfy the
407 /// given predicate.
408 template <class PredicateT>
409 MutableArrayRef<T> take_until(PredicateT Pred) const {
410 return MutableArrayRef<T>(begin(), find_if(*this, Pred));
411 }
412
413 /// @}
414 /// @name Operator Overloads
415 /// @{
416 T &operator[](size_t Index) const {
417 assert(Index < this->size() && "Invalid index!");
418 return data()[Index];
419 }
420 };
421
422 /// This is a MutableArrayRef that owns its array.
423 template <typename T> class OwningArrayRef : public MutableArrayRef<T> {
424 public:
425 OwningArrayRef() = default;
426 OwningArrayRef(size_t Size) : MutableArrayRef<T>(new T[Size], Size) {}
427
428 OwningArrayRef(ArrayRef<T> Data)
429 : MutableArrayRef<T>(new T[Data.size()], Data.size()) {
430 std::copy(Data.begin(), Data.end(), this->begin());
431 }
432
433 OwningArrayRef(OwningArrayRef &&Other) { *this = Other; }
434
435 OwningArrayRef &operator=(OwningArrayRef &&Other) {
436 delete[] this->data();
437 this->MutableArrayRef<T>::operator=(Other);
438 Other.MutableArrayRef<T>::operator=(MutableArrayRef<T>());
439 return *this;
440 }
441
442 ~OwningArrayRef() { delete[] this->data(); }
443 };
444
445 /// @name ArrayRef Convenience constructors
446 /// @{
447
448 /// Construct an ArrayRef from a single element.
449 template<typename T>
450 ArrayRef<T> makeArrayRef(const T &OneElt) {
451 return OneElt;
452 }
453
454 /// Construct an ArrayRef from a pointer and length.
455 template<typename T>
456 ArrayRef<T> makeArrayRef(const T *data, size_t length) {
457 return ArrayRef<T>(data, length);
458 }
459
460 /// Construct an ArrayRef from a range.
461 template<typename T>
462 ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
463 return ArrayRef<T>(begin, end);
464 }
465
466 /// Construct an ArrayRef from a SmallVector.
467 template <typename T>
468 ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
469 return Vec;
470 }
471
472 /// Construct an ArrayRef from a SmallVector.
473 template <typename T, unsigned N>
474 ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
475 return Vec;
476 }
477
478 /// Construct an ArrayRef from a std::vector.
479 template<typename T>
480 ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
481 return Vec;
482 }
483
484 /// Construct an ArrayRef from an ArrayRef (no-op) (const)
485 template <typename T> ArrayRef<T> makeArrayRef(const ArrayRef<T> &Vec) {
486 return Vec;
487 }
488
489 /// Construct an ArrayRef from an ArrayRef (no-op)
490 template <typename T> ArrayRef<T> &makeArrayRef(ArrayRef<T> &Vec) {
491 return Vec;
492 }
493
494 /// Construct an ArrayRef from a C array.
495 template<typename T, size_t N>
496 ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
497 return ArrayRef<T>(Arr);
498 }
499
500 /// Construct a MutableArrayRef from a single element.
501 template<typename T>
502 MutableArrayRef<T> makeMutableArrayRef(T &OneElt) {
503 return OneElt;
504 }
505
506 /// Construct a MutableArrayRef from a pointer and length.
507 template<typename T>
508 MutableArrayRef<T> makeMutableArrayRef(T *data, size_t length) {
509 return MutableArrayRef<T>(data, length);
510 }
511
512 /// @}
513 /// @name ArrayRef Comparison Operators
514 /// @{
515
516 template<typename T>
517 inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
518 return LHS.equals(RHS);
519 }
520
521 template<typename T>
522 inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
523 return !(LHS == RHS);
524 }
525
526 /// @}
527
528 template <typename T> hash_code hash_value(ArrayRef<T> S) {
529 return hash_combine_range(S.begin(), S.end());
530 }
531
532} // end namespace llvm
533
534#endif // LLVM_ADT_ARRAYREF_H
535