1 //===--- ArrayRef.h - Array Reference Wrapper -------------------*- 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 #ifndef LLVM_ADT_ARRAYREF_H
11 #define LLVM_ADT_ARRAYREF_H
13 #include "llvm/ADT/None.h"
14 #include "llvm/ADT/STLExtras.h"
15 #include "llvm/ADT/SmallVector.h"
20 /// ArrayRef - Represent a constant reference to an array (0 or more elements
21 /// consecutively in memory), i.e. a start pointer and a length. It allows
22 /// various APIs to take consecutive elements easily and conveniently.
24 /// This class does not own the underlying data, it is expected to be used in
25 /// situations where the data resides in some other buffer, whose lifetime
26 /// extends past that of the ArrayRef. For this reason, it is not in general
27 /// safe to store an ArrayRef.
29 /// This is intended to be trivially copyable, so it should be passed by
34 typedef const T *iterator;
35 typedef const T *const_iterator;
36 typedef size_t size_type;
38 typedef std::reverse_iterator<iterator> reverse_iterator;
41 /// The start of the array, in an external buffer.
44 /// The number of elements.
47 /// \brief A dummy "optional" type that is only created by implicit
48 /// conversion from a reference to T.
50 /// This type must *only* be used in a function argument or as a copy of
51 /// a function argument, as otherwise it will hold a pointer to a temporary
52 /// past that temporaries' lifetime.
53 struct TRefOrNothing {
56 TRefOrNothing() : TPtr(nullptr) {}
57 TRefOrNothing(const T &TRef) : TPtr(&TRef) {}
61 /// @name Constructors
64 /// Construct an empty ArrayRef.
65 /*implicit*/ ArrayRef() : Data(nullptr), Length(0) {}
67 /// Construct an empty ArrayRef from None.
68 /*implicit*/ ArrayRef(NoneType) : Data(nullptr), Length(0) {}
70 /// Construct an ArrayRef from a single element.
71 /*implicit*/ ArrayRef(const T &OneElt)
72 : Data(&OneElt), Length(1) {}
74 /// Construct an ArrayRef from a pointer and length.
75 /*implicit*/ ArrayRef(const T *data, size_t length)
76 : Data(data), Length(length) {}
78 /// Construct an ArrayRef from a range.
79 ArrayRef(const T *begin, const T *end)
80 : Data(begin), Length(end - begin) {}
82 /// Construct an ArrayRef from a SmallVector. This is templated in order to
83 /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
84 /// copy-construct an ArrayRef.
86 /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
87 : Data(Vec.data()), Length(Vec.size()) {
90 /// Construct an ArrayRef from a std::vector.
92 /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
93 : Data(Vec.data()), Length(Vec.size()) {}
95 /// Construct an ArrayRef from a C array.
97 /*implicit*/ LLVM_CONSTEXPR ArrayRef(const T (&Arr)[N])
98 : Data(Arr), Length(N) {}
100 /// Construct an ArrayRef from a std::initializer_list.
101 /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
102 : Data(Vec.begin() == Vec.end() ? (T*)0 : Vec.begin()),
103 Length(Vec.size()) {}
105 /// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to
106 /// ensure that only ArrayRefs of pointers can be converted.
107 template <typename U>
108 ArrayRef(const ArrayRef<U *> &A,
109 typename std::enable_if<
110 std::is_convertible<U *const *, T const *>::value>::type* = 0)
111 : Data(A.data()), Length(A.size()) {}
114 /// @name Simple Operations
117 iterator begin() const { return Data; }
118 iterator end() const { return Data + Length; }
120 reverse_iterator rbegin() const { return reverse_iterator(end()); }
121 reverse_iterator rend() const { return reverse_iterator(begin()); }
123 /// empty - Check if the array is empty.
124 bool empty() const { return Length == 0; }
126 const T *data() const { return Data; }
128 /// size - Get the array size.
129 size_t size() const { return Length; }
131 /// front - Get the first element.
132 const T &front() const {
137 /// back - Get the last element.
138 const T &back() const {
140 return Data[Length-1];
143 // copy - Allocate copy in Allocator and return ArrayRef<T> to it.
144 template <typename Allocator> ArrayRef<T> copy(Allocator &A) {
145 T *Buff = A.template Allocate<T>(Length);
146 std::copy(begin(), end(), Buff);
147 return ArrayRef<T>(Buff, Length);
150 /// equals - Check for element-wise equality.
151 bool equals(ArrayRef RHS) const {
152 if (Length != RHS.Length)
154 // Don't use std::equal(), since it asserts in MSVC on nullptr iterators.
155 for (auto L = begin(), LE = end(), R = RHS.begin(); L != LE; ++L, ++R)
156 // Match std::equal() in using == (instead of !=) to minimize API
157 // requirements of ArrayRef'ed types.
163 /// slice(n) - Chop off the first N elements of the array.
164 ArrayRef<T> slice(unsigned N) const {
165 assert(N <= size() && "Invalid specifier");
166 return ArrayRef<T>(data()+N, size()-N);
169 /// slice(n, m) - Chop off the first N elements of the array, and keep M
170 /// elements in the array.
171 ArrayRef<T> slice(unsigned N, unsigned M) const {
172 assert(N+M <= size() && "Invalid specifier");
173 return ArrayRef<T>(data()+N, M);
176 // \brief Drop the last \p N elements of the array.
177 ArrayRef<T> drop_back(unsigned N = 1) const {
178 assert(size() >= N && "Dropping more elements than exist");
179 return slice(0, size() - N);
183 /// @name Operator Overloads
185 const T &operator[](size_t Index) const {
186 assert(Index < Length && "Invalid index!");
191 /// @name Expensive Operations
193 std::vector<T> vec() const {
194 return std::vector<T>(Data, Data+Length);
198 /// @name Conversion operators
200 operator std::vector<T>() const {
201 return std::vector<T>(Data, Data+Length);
206 /// @name Convenience methods
208 /// @brief Predicate for testing that the array equals the exact sequence of
211 /// Will return false if the size is not equal to the exact number of
212 /// arguments given or if the array elements don't equal the argument
213 /// elements in order. Currently supports up to 16 arguments, but can
214 /// easily be extended.
215 bool equals(TRefOrNothing Arg0 = TRefOrNothing(),
216 TRefOrNothing Arg1 = TRefOrNothing(),
217 TRefOrNothing Arg2 = TRefOrNothing(),
218 TRefOrNothing Arg3 = TRefOrNothing(),
219 TRefOrNothing Arg4 = TRefOrNothing(),
220 TRefOrNothing Arg5 = TRefOrNothing(),
221 TRefOrNothing Arg6 = TRefOrNothing(),
222 TRefOrNothing Arg7 = TRefOrNothing(),
223 TRefOrNothing Arg8 = TRefOrNothing(),
224 TRefOrNothing Arg9 = TRefOrNothing(),
225 TRefOrNothing Arg10 = TRefOrNothing(),
226 TRefOrNothing Arg11 = TRefOrNothing(),
227 TRefOrNothing Arg12 = TRefOrNothing(),
228 TRefOrNothing Arg13 = TRefOrNothing(),
229 TRefOrNothing Arg14 = TRefOrNothing(),
230 TRefOrNothing Arg15 = TRefOrNothing()) {
231 TRefOrNothing Args[] = {Arg0, Arg1, Arg2, Arg3, Arg4, Arg5,
232 Arg6, Arg7, Arg8, Arg9, Arg10, Arg11,
233 Arg12, Arg13, Arg14, Arg15};
234 if (size() > array_lengthof(Args))
237 for (unsigned i = 0, e = size(); i != e; ++i)
238 if (Args[i].TPtr == nullptr || (*this)[i] != *Args[i].TPtr)
241 // Either the size is exactly as many args, or the next arg must be null.
242 return size() == array_lengthof(Args) || Args[size()].TPtr == nullptr;
248 /// MutableArrayRef - Represent a mutable reference to an array (0 or more
249 /// elements consecutively in memory), i.e. a start pointer and a length. It
250 /// allows various APIs to take and modify consecutive elements easily and
253 /// This class does not own the underlying data, it is expected to be used in
254 /// situations where the data resides in some other buffer, whose lifetime
255 /// extends past that of the MutableArrayRef. For this reason, it is not in
256 /// general safe to store a MutableArrayRef.
258 /// This is intended to be trivially copyable, so it should be passed by
261 class MutableArrayRef : public ArrayRef<T> {
265 typedef std::reverse_iterator<iterator> reverse_iterator;
267 /// Construct an empty MutableArrayRef.
268 /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
270 /// Construct an empty MutableArrayRef from None.
271 /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
273 /// Construct an MutableArrayRef from a single element.
274 /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
276 /// Construct an MutableArrayRef from a pointer and length.
277 /*implicit*/ MutableArrayRef(T *data, size_t length)
278 : ArrayRef<T>(data, length) {}
280 /// Construct an MutableArrayRef from a range.
281 MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
283 /// Construct an MutableArrayRef from a SmallVector.
284 /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
285 : ArrayRef<T>(Vec) {}
287 /// Construct a MutableArrayRef from a std::vector.
288 /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
289 : ArrayRef<T>(Vec) {}
291 /// Construct an MutableArrayRef from a C array.
293 /*implicit*/ LLVM_CONSTEXPR MutableArrayRef(T (&Arr)[N])
294 : ArrayRef<T>(Arr) {}
296 T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
298 iterator begin() const { return data(); }
299 iterator end() const { return data() + this->size(); }
301 reverse_iterator rbegin() const { return reverse_iterator(end()); }
302 reverse_iterator rend() const { return reverse_iterator(begin()); }
304 /// front - Get the first element.
306 assert(!this->empty());
310 /// back - Get the last element.
312 assert(!this->empty());
313 return data()[this->size()-1];
316 /// slice(n) - Chop off the first N elements of the array.
317 MutableArrayRef<T> slice(unsigned N) const {
318 assert(N <= this->size() && "Invalid specifier");
319 return MutableArrayRef<T>(data()+N, this->size()-N);
322 /// slice(n, m) - Chop off the first N elements of the array, and keep M
323 /// elements in the array.
324 MutableArrayRef<T> slice(unsigned N, unsigned M) const {
325 assert(N+M <= this->size() && "Invalid specifier");
326 return MutableArrayRef<T>(data()+N, M);
330 /// @name Operator Overloads
332 T &operator[](size_t Index) const {
333 assert(Index < this->size() && "Invalid index!");
334 return data()[Index];
338 /// @name ArrayRef Convenience constructors
341 /// Construct an ArrayRef from a single element.
343 ArrayRef<T> makeArrayRef(const T &OneElt) {
347 /// Construct an ArrayRef from a pointer and length.
349 ArrayRef<T> makeArrayRef(const T *data, size_t length) {
350 return ArrayRef<T>(data, length);
353 /// Construct an ArrayRef from a range.
355 ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
356 return ArrayRef<T>(begin, end);
359 /// Construct an ArrayRef from a SmallVector.
360 template <typename T>
361 ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
365 /// Construct an ArrayRef from a SmallVector.
366 template <typename T, unsigned N>
367 ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
371 /// Construct an ArrayRef from a std::vector.
373 ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
377 /// Construct an ArrayRef from a C array.
378 template<typename T, size_t N>
379 ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
380 return ArrayRef<T>(Arr);
384 /// @name ArrayRef Comparison Operators
388 inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
389 return LHS.equals(RHS);
393 inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
394 return !(LHS == RHS);
399 // ArrayRefs can be treated like a POD type.
400 template <typename T> struct isPodLike;
401 template <typename T> struct isPodLike<ArrayRef<T> > {
402 static const bool value = true;