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_GSL_POINTER LLVM_NODISCARD ArrayRef {
42 public:
43 using value_type = T;
44 using pointer = value_type *;
45 using const_pointer = const value_type *;
46 using reference = value_type &;
47 using const_reference = const value_type &;
48 using iterator = const_pointer;
49 using const_iterator = const_pointer;
50 using reverse_iterator = std::reverse_iterator<iterator>;
51 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
52 using size_type = size_t;
53 using difference_type = ptrdiff_t;
54
55 private:
56 /// The start of the array, in an external buffer.
57 const T *Data = nullptr;
58
59 /// The number of elements.
60 size_type Length = 0;
61
62 public:
63 /// @name Constructors
64 /// @{
65
66 /// Construct an empty ArrayRef.
67 /*implicit*/ ArrayRef() = default;
68
69 /// Construct an empty ArrayRef from None.
70 /*implicit*/ ArrayRef(NoneType) {}
71
72 /// Construct an ArrayRef from a single element.
73 /*implicit*/ ArrayRef(const T &OneElt)
74 : Data(&OneElt), Length(1) {}
75
76 /// Construct an ArrayRef from a pointer and length.
77 /*implicit*/ ArrayRef(const T *data, size_t length)
78 : Data(data), Length(length) {}
79
80 /// Construct an ArrayRef from a range.
81 ArrayRef(const T *begin, const T *end)
82 : Data(begin), Length(end - begin) {}
83
84 /// Construct an ArrayRef from a SmallVector. This is templated in order to
85 /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
86 /// copy-construct an ArrayRef.
87 template<typename U>
88 /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
89 : Data(Vec.data()), Length(Vec.size()) {
90 }
91
92 /// Construct an ArrayRef from a std::vector.
93 template<typename A>
94 /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
95 : Data(Vec.data()), Length(Vec.size()) {}
96
97 /// Construct an ArrayRef from a std::array
98 template <size_t N>
99 /*implicit*/ constexpr ArrayRef(const std::array<T, N> &Arr)
100 : Data(Arr.data()), Length(N) {}
101
102 /// Construct an ArrayRef from a C array.
103 template <size_t N>
104 /*implicit*/ constexpr ArrayRef(const T (&Arr)[N]) : Data(Arr), Length(N) {}
105
106 /// Construct an ArrayRef from a std::initializer_list.
107#if LLVM_GNUC_PREREQ(9, 0, 0)
108// Disable gcc's warning in this constructor as it generates an enormous amount
109// of messages. Anyone using ArrayRef should already be aware of the fact that
110// it does not do lifetime extension.
111#pragma GCC diagnostic push
112#pragma GCC diagnostic ignored "-Winit-list-lifetime"
113#endif
114 /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
115 : Data(Vec.begin() == Vec.end() ? (T*)nullptr : Vec.begin()),
116 Length(Vec.size()) {}
117#if LLVM_GNUC_PREREQ(9, 0, 0)
118#pragma GCC diagnostic pop
119#endif
120
121 /// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to
122 /// ensure that only ArrayRefs of pointers can be converted.
123 template <typename U>
124 ArrayRef(const ArrayRef<U *> &A,
125 std::enable_if_t<std::is_convertible<U *const *, T const *>::value>
126 * = nullptr)
127 : Data(A.data()), Length(A.size()) {}
128
129 /// Construct an ArrayRef<const T*> from a SmallVector<T*>. This is
130 /// templated in order to avoid instantiating SmallVectorTemplateCommon<T>
131 /// whenever we copy-construct an ArrayRef.
132 template <typename U, typename DummyT>
133 /*implicit*/ ArrayRef(
134 const SmallVectorTemplateCommon<U *, DummyT> &Vec,
135 std::enable_if_t<std::is_convertible<U *const *, T const *>::value> * =
136 nullptr)
137 : Data(Vec.data()), Length(Vec.size()) {}
138
139 /// Construct an ArrayRef<const T*> from std::vector<T*>. This uses SFINAE
140 /// to ensure that only vectors of pointers can be converted.
141 template <typename U, typename A>
142 ArrayRef(const std::vector<U *, A> &Vec,
143 std::enable_if_t<std::is_convertible<U *const *, T const *>::value>
144 * = 0)
145 : Data(Vec.data()), Length(Vec.size()) {}
146
147 /// @}
148 /// @name Simple Operations
149 /// @{
150
151 iterator begin() const { return Data; }
152 iterator end() const { return Data + Length; }
153
154 reverse_iterator rbegin() const { return reverse_iterator(end()); }
155 reverse_iterator rend() const { return reverse_iterator(begin()); }
156
157 /// empty - Check if the array is empty.
158 bool empty() const { return Length == 0; }
159
160 const T *data() const { return Data; }
161
162 /// size - Get the array size.
163 size_t size() const { return Length; }
164
165 /// front - Get the first element.
166 const T &front() const {
167 assert(!empty());
168 return Data[0];
169 }
170
171 /// back - Get the last element.
172 const T &back() const {
173 assert(!empty());
174 return Data[Length-1];
175 }
176
177 // copy - Allocate copy in Allocator and return ArrayRef<T> to it.
178 template <typename Allocator> ArrayRef<T> copy(Allocator &A) {
179 T *Buff = A.template Allocate<T>(Length);
180 std::uninitialized_copy(begin(), end(), Buff);
181 return ArrayRef<T>(Buff, Length);
182 }
183
184 /// equals - Check for element-wise equality.
185 bool equals(ArrayRef RHS) const {
186 if (Length != RHS.Length)
187 return false;
188 return std::equal(begin(), end(), RHS.begin());
189 }
190
191 /// slice(n, m) - Chop off the first N elements of the array, and keep M
192 /// elements in the array.
193 ArrayRef<T> slice(size_t N, size_t M) const {
194 assert(N+M <= size() && "Invalid specifier");
195 return ArrayRef<T>(data()+N, M);
196 }
197
198 /// slice(n) - Chop off the first N elements of the array.
199 ArrayRef<T> slice(size_t N) const { return slice(N, size() - N); }
200
201 /// Drop the first \p N elements of the array.
202 ArrayRef<T> drop_front(size_t N = 1) const {
203 assert(size() >= N && "Dropping more elements than exist");
204 return slice(N, size() - N);
205 }
206
207 /// Drop the last \p N elements of the array.
208 ArrayRef<T> drop_back(size_t N = 1) const {
209 assert(size() >= N && "Dropping more elements than exist");
210 return slice(0, size() - N);
211 }
212
213 /// Return a copy of *this with the first N elements satisfying the
214 /// given predicate removed.
215 template <class PredicateT> ArrayRef<T> drop_while(PredicateT Pred) const {
216 return ArrayRef<T>(find_if_not(*this, Pred), end());
217 }
218
219 /// Return a copy of *this with the first N elements not satisfying
220 /// the given predicate removed.
221 template <class PredicateT> ArrayRef<T> drop_until(PredicateT Pred) const {
222 return ArrayRef<T>(find_if(*this, Pred), end());
223 }
224
225 /// Return a copy of *this with only the first \p N elements.
226 ArrayRef<T> take_front(size_t N = 1) const {
227 if (N >= size())
228 return *this;
229 return drop_back(size() - N);
230 }
231
232 /// Return a copy of *this with only the last \p N elements.
233 ArrayRef<T> take_back(size_t N = 1) const {
234 if (N >= size())
235 return *this;
236 return drop_front(size() - N);
237 }
238
239 /// Return the first N elements of this Array that satisfy the given
240 /// predicate.
241 template <class PredicateT> ArrayRef<T> take_while(PredicateT Pred) const {
242 return ArrayRef<T>(begin(), find_if_not(*this, Pred));
243 }
244
245 /// Return the first N elements of this Array that don't satisfy the
246 /// given predicate.
247 template <class PredicateT> ArrayRef<T> take_until(PredicateT Pred) const {
248 return ArrayRef<T>(begin(), find_if(*this, Pred));
249 }
250
251 /// @}
252 /// @name Operator Overloads
253 /// @{
254 const T &operator[](size_t Index) const {
255 assert(Index < Length && "Invalid index!");
256 return Data[Index];
257 }
258
259 /// Disallow accidental assignment from a temporary.
260 ///
261 /// The declaration here is extra complicated so that "arrayRef = {}"
262 /// continues to select the move assignment operator.
263 template <typename U>
264 std::enable_if_t<std::is_same<U, T>::value, ArrayRef<T>> &
265 operator=(U &&Temporary) = delete;
266
267 /// Disallow accidental assignment from a temporary.
268 ///
269 /// The declaration here is extra complicated so that "arrayRef = {}"
270 /// continues to select the move assignment operator.
271 template <typename U>
272 std::enable_if_t<std::is_same<U, T>::value, ArrayRef<T>> &
273 operator=(std::initializer_list<U>) = delete;
274
275 /// @}
276 /// @name Expensive Operations
277 /// @{
278 std::vector<T> vec() const {
279 return std::vector<T>(Data, Data+Length);
280 }
281
282 /// @}
283 /// @name Conversion operators
284 /// @{
285 operator std::vector<T>() const {
286 return std::vector<T>(Data, Data+Length);
287 }
288
289 /// @}
290 };
291
292 /// MutableArrayRef - Represent a mutable reference to an array (0 or more
293 /// elements consecutively in memory), i.e. a start pointer and a length. It
294 /// allows various APIs to take and modify consecutive elements easily and
295 /// conveniently.
296 ///
297 /// This class does not own the underlying data, it is expected to be used in
298 /// situations where the data resides in some other buffer, whose lifetime
299 /// extends past that of the MutableArrayRef. For this reason, it is not in
300 /// general safe to store a MutableArrayRef.
301 ///
302 /// This is intended to be trivially copyable, so it should be passed by
303 /// value.
304 template<typename T>
305 class LLVM_NODISCARD MutableArrayRef : public ArrayRef<T> {
306 public:
307 using value_type = T;
308 using pointer = value_type *;
309 using const_pointer = const value_type *;
310 using reference = value_type &;
311 using const_reference = const value_type &;
312 using iterator = pointer;
313 using const_iterator = const_pointer;
314 using reverse_iterator = std::reverse_iterator<iterator>;
315 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
316 using size_type = size_t;
317 using difference_type = ptrdiff_t;
318
319 /// Construct an empty MutableArrayRef.
320 /*implicit*/ MutableArrayRef() = default;
321
322 /// Construct an empty MutableArrayRef from None.
323 /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
324
325 /// Construct a MutableArrayRef from a single element.
326 /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
327
328 /// Construct a MutableArrayRef from a pointer and length.
329 /*implicit*/ MutableArrayRef(T *data, size_t length)
330 : ArrayRef<T>(data, length) {}
331
332 /// Construct a MutableArrayRef from a range.
333 MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
334
335 /// Construct a MutableArrayRef from a SmallVector.
336 /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
337 : ArrayRef<T>(Vec) {}
338
339 /// Construct a MutableArrayRef from a std::vector.
340 /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
341 : ArrayRef<T>(Vec) {}
342
343 /// Construct a MutableArrayRef from a std::array
344 template <size_t N>
345 /*implicit*/ constexpr MutableArrayRef(std::array<T, N> &Arr)
346 : ArrayRef<T>(Arr) {}
347
348 /// Construct a MutableArrayRef from a C array.
349 template <size_t N>
350 /*implicit*/ constexpr MutableArrayRef(T (&Arr)[N]) : ArrayRef<T>(Arr) {}
351
352 T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
353
354 iterator begin() const { return data(); }
355 iterator end() const { return data() + this->size(); }
356
357 reverse_iterator rbegin() const { return reverse_iterator(end()); }
358 reverse_iterator rend() const { return reverse_iterator(begin()); }
359
360 /// front - Get the first element.
361 T &front() const {
362 assert(!this->empty());
363 return data()[0];
364 }
365
366 /// back - Get the last element.
367 T &back() const {
368 assert(!this->empty());
369 return data()[this->size()-1];
370 }
371
372 /// slice(n, m) - Chop off the first N elements of the array, and keep M
373 /// elements in the array.
374 MutableArrayRef<T> slice(size_t N, size_t M) const {
375 assert(N + M <= this->size() && "Invalid specifier");
376 return MutableArrayRef<T>(this->data() + N, M);
377 }
378
379 /// slice(n) - Chop off the first N elements of the array.
380 MutableArrayRef<T> slice(size_t N) const {
381 return slice(N, this->size() - N);
382 }
383
384 /// Drop the first \p N elements of the array.
385 MutableArrayRef<T> drop_front(size_t N = 1) const {
386 assert(this->size() >= N && "Dropping more elements than exist");
387 return slice(N, this->size() - N);
388 }
389
390 MutableArrayRef<T> drop_back(size_t N = 1) const {
391 assert(this->size() >= N && "Dropping more elements than exist");
392 return slice(0, this->size() - N);
393 }
394
395 /// Return a copy of *this with the first N elements satisfying the
396 /// given predicate removed.
397 template <class PredicateT>
398 MutableArrayRef<T> drop_while(PredicateT Pred) const {
399 return MutableArrayRef<T>(find_if_not(*this, Pred), end());
400 }
401
402 /// Return a copy of *this with the first N elements not satisfying
403 /// the given predicate removed.
404 template <class PredicateT>
405 MutableArrayRef<T> drop_until(PredicateT Pred) const {
406 return MutableArrayRef<T>(find_if(*this, Pred), end());
407 }
408
409 /// Return a copy of *this with only the first \p N elements.
410 MutableArrayRef<T> take_front(size_t N = 1) const {
411 if (N >= this->size())
412 return *this;
413 return drop_back(this->size() - N);
414 }
415
416 /// Return a copy of *this with only the last \p N elements.
417 MutableArrayRef<T> take_back(size_t N = 1) const {
418 if (N >= this->size())
419 return *this;
420 return drop_front(this->size() - N);
421 }
422
423 /// Return the first N elements of this Array that satisfy the given
424 /// predicate.
425 template <class PredicateT>
426 MutableArrayRef<T> take_while(PredicateT Pred) const {
427 return MutableArrayRef<T>(begin(), find_if_not(*this, Pred));
428 }
429
430 /// Return the first N elements of this Array that don't satisfy the
431 /// given predicate.
432 template <class PredicateT>
433 MutableArrayRef<T> take_until(PredicateT Pred) const {
434 return MutableArrayRef<T>(begin(), find_if(*this, Pred));
435 }
436
437 /// @}
438 /// @name Operator Overloads
439 /// @{
440 T &operator[](size_t Index) const {
441 assert(Index < this->size() && "Invalid index!");
442 return data()[Index];
443 }
444 };
445
446 /// This is a MutableArrayRef that owns its array.
447 template <typename T> class OwningArrayRef : public MutableArrayRef<T> {
448 public:
449 OwningArrayRef() = default;
450 OwningArrayRef(size_t Size) : MutableArrayRef<T>(new T[Size], Size) {}
451
452 OwningArrayRef(ArrayRef<T> Data)
453 : MutableArrayRef<T>(new T[Data.size()], Data.size()) {
454 std::copy(Data.begin(), Data.end(), this->begin());
455 }
456
457 OwningArrayRef(OwningArrayRef &&Other) { *this = std::move(Other); }
458
459 OwningArrayRef &operator=(OwningArrayRef &&Other) {
460 delete[] this->data();
461 this->MutableArrayRef<T>::operator=(Other);
462 Other.MutableArrayRef<T>::operator=(MutableArrayRef<T>());
463 return *this;
464 }
465
466 ~OwningArrayRef() { delete[] this->data(); }
467 };
468
469 /// @name ArrayRef Convenience constructors
470 /// @{
471
472 /// Construct an ArrayRef from a single element.
473 template<typename T>
474 ArrayRef<T> makeArrayRef(const T &OneElt) {
475 return OneElt;
476 }
477
478 /// Construct an ArrayRef from a pointer and length.
479 template<typename T>
480 ArrayRef<T> makeArrayRef(const T *data, size_t length) {
481 return ArrayRef<T>(data, length);
482 }
483
484 /// Construct an ArrayRef from a range.
485 template<typename T>
486 ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
487 return ArrayRef<T>(begin, end);
488 }
489
490 /// Construct an ArrayRef from a SmallVector.
491 template <typename T>
492 ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
493 return Vec;
494 }
495
496 /// Construct an ArrayRef from a SmallVector.
497 template <typename T, unsigned N>
498 ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
499 return Vec;
500 }
501
502 /// Construct an ArrayRef from a std::vector.
503 template<typename T>
504 ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
505 return Vec;
506 }
507
508 /// Construct an ArrayRef from a std::array.
509 template <typename T, std::size_t N>
510 ArrayRef<T> makeArrayRef(const std::array<T, N> &Arr) {
511 return Arr;
512 }
513
514 /// Construct an ArrayRef from an ArrayRef (no-op) (const)
515 template <typename T> ArrayRef<T> makeArrayRef(const ArrayRef<T> &Vec) {
516 return Vec;
517 }
518
519 /// Construct an ArrayRef from an ArrayRef (no-op)
520 template <typename T> ArrayRef<T> &makeArrayRef(ArrayRef<T> &Vec) {
521 return Vec;
522 }
523
524 /// Construct an ArrayRef from a C array.
525 template<typename T, size_t N>
526 ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
527 return ArrayRef<T>(Arr);
528 }
529
530 /// Construct a MutableArrayRef from a single element.
531 template<typename T>
532 MutableArrayRef<T> makeMutableArrayRef(T &OneElt) {
533 return OneElt;
534 }
535
536 /// Construct a MutableArrayRef from a pointer and length.
537 template<typename T>
538 MutableArrayRef<T> makeMutableArrayRef(T *data, size_t length) {
539 return MutableArrayRef<T>(data, length);
540 }
541
542 /// @}
543 /// @name ArrayRef Comparison Operators
544 /// @{
545
546 template<typename T>
547 inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
548 return LHS.equals(RHS);
549 }
550
551 template <typename T>
552 inline bool operator==(SmallVectorImpl<T> &LHS, ArrayRef<T> RHS) {
553 return ArrayRef<T>(LHS).equals(RHS);
554 }
555
556 template <typename T>
557 inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
558 return !(LHS == RHS);
559 }
560
561 template <typename T>
562 inline bool operator!=(SmallVectorImpl<T> &LHS, ArrayRef<T> RHS) {
563 return !(LHS == RHS);
564 }
565
566 /// @}
567
568 template <typename T> hash_code hash_value(ArrayRef<T> S) {
569 return hash_combine_range(S.begin(), S.end());
570 }
571
572} // end namespace llvm
573
574#endif // LLVM_ADT_ARRAYREF_H
575