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/SmallVector.h"
19 /// ArrayRef - Represent a constant reference to an array (0 or more elements
20 /// consecutively in memory), i.e. a start pointer and a length. It allows
21 /// various APIs to take consecutive elements easily and conveniently.
23 /// This class does not own the underlying data, it is expected to be used in
24 /// situations where the data resides in some other buffer, whose lifetime
25 /// extends past that of the ArrayRef. For this reason, it is not in general
26 /// safe to store an ArrayRef.
28 /// This is intended to be trivially copyable, so it should be passed by
33 typedef const T *iterator;
34 typedef const T *const_iterator;
35 typedef size_t size_type;
37 typedef std::reverse_iterator<iterator> reverse_iterator;
40 /// The start of the array, in an external buffer.
43 /// The number of elements.
47 /// @name Constructors
50 /// Construct an empty ArrayRef.
51 /*implicit*/ ArrayRef() : Data(nullptr), Length(0) {}
53 /// Construct an empty ArrayRef from None.
54 /*implicit*/ ArrayRef(NoneType) : Data(nullptr), Length(0) {}
56 /// Construct an ArrayRef from a single element.
57 /*implicit*/ ArrayRef(const T &OneElt)
58 : Data(&OneElt), Length(1) {}
60 /// Construct an ArrayRef from a pointer and length.
61 /*implicit*/ ArrayRef(const T *data, size_t length)
62 : Data(data), Length(length) {}
64 /// Construct an ArrayRef from a range.
65 ArrayRef(const T *begin, const T *end)
66 : Data(begin), Length(end - begin) {}
68 /// Construct an ArrayRef from a SmallVector. This is templated in order to
69 /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
70 /// copy-construct an ArrayRef.
72 /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
73 : Data(Vec.data()), Length(Vec.size()) {
76 /// Construct an ArrayRef from a std::vector.
78 /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
79 : Data(Vec.data()), Length(Vec.size()) {}
81 /// Construct an ArrayRef from a C array.
83 /*implicit*/ LLVM_CONSTEXPR ArrayRef(const T (&Arr)[N])
84 : Data(Arr), Length(N) {}
86 /// Construct an ArrayRef from a std::initializer_list.
87 /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
88 : Data(Vec.begin() == Vec.end() ? (T*)0 : Vec.begin()),
91 /// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to
92 /// ensure that only ArrayRefs of pointers can be converted.
94 ArrayRef(const ArrayRef<U *> &A,
95 typename std::enable_if<
96 std::is_convertible<U *const *, T const *>::value>::type* = 0)
97 : Data(A.data()), Length(A.size()) {}
100 /// @name Simple Operations
103 iterator begin() const { return Data; }
104 iterator end() const { return Data + Length; }
106 reverse_iterator rbegin() const { return reverse_iterator(end()); }
107 reverse_iterator rend() const { return reverse_iterator(begin()); }
109 /// empty - Check if the array is empty.
110 bool empty() const { return Length == 0; }
112 const T *data() const { return Data; }
114 /// size - Get the array size.
115 size_t size() const { return Length; }
117 /// front - Get the first element.
118 const T &front() const {
123 /// back - Get the last element.
124 const T &back() const {
126 return Data[Length-1];
129 // copy - Allocate copy in Allocator and return ArrayRef<T> to it.
130 template <typename Allocator> ArrayRef<T> copy(Allocator &A) {
131 T *Buff = A.template Allocate<T>(Length);
132 std::copy(begin(), end(), Buff);
133 return ArrayRef<T>(Buff, Length);
136 /// equals - Check for element-wise equality.
137 bool equals(ArrayRef RHS) const {
138 if (Length != RHS.Length || Length == 0)
140 return std::equal(begin(), end(), RHS.begin());
143 /// slice(n) - Chop off the first N elements of the array.
144 ArrayRef<T> slice(unsigned N) const {
145 assert(N <= size() && "Invalid specifier");
146 return ArrayRef<T>(data()+N, size()-N);
149 /// slice(n, m) - Chop off the first N elements of the array, and keep M
150 /// elements in the array.
151 ArrayRef<T> slice(unsigned N, unsigned M) const {
152 assert(N+M <= size() && "Invalid specifier");
153 return ArrayRef<T>(data()+N, M);
156 // \brief Drop the last \p N elements of the array.
157 ArrayRef<T> drop_back(unsigned N = 1) const {
158 assert(size() >= N && "Dropping more elements than exist");
159 return slice(0, size() - N);
163 /// @name Operator Overloads
165 const T &operator[](size_t Index) const {
166 assert(Index < Length && "Invalid index!");
171 /// @name Expensive Operations
173 std::vector<T> vec() const {
174 return std::vector<T>(Data, Data+Length);
178 /// @name Conversion operators
180 operator std::vector<T>() const {
181 return std::vector<T>(Data, Data+Length);
187 /// MutableArrayRef - Represent a mutable reference to an array (0 or more
188 /// elements consecutively in memory), i.e. a start pointer and a length. It
189 /// allows various APIs to take and modify consecutive elements easily and
192 /// This class does not own the underlying data, it is expected to be used in
193 /// situations where the data resides in some other buffer, whose lifetime
194 /// extends past that of the MutableArrayRef. For this reason, it is not in
195 /// general safe to store a MutableArrayRef.
197 /// This is intended to be trivially copyable, so it should be passed by
200 class MutableArrayRef : public ArrayRef<T> {
204 typedef std::reverse_iterator<iterator> reverse_iterator;
206 /// Construct an empty MutableArrayRef.
207 /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
209 /// Construct an empty MutableArrayRef from None.
210 /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
212 /// Construct an MutableArrayRef from a single element.
213 /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
215 /// Construct an MutableArrayRef from a pointer and length.
216 /*implicit*/ MutableArrayRef(T *data, size_t length)
217 : ArrayRef<T>(data, length) {}
219 /// Construct an MutableArrayRef from a range.
220 MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
222 /// Construct an MutableArrayRef from a SmallVector.
223 /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
224 : ArrayRef<T>(Vec) {}
226 /// Construct a MutableArrayRef from a std::vector.
227 /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
228 : ArrayRef<T>(Vec) {}
230 /// Construct an MutableArrayRef from a C array.
232 /*implicit*/ LLVM_CONSTEXPR MutableArrayRef(T (&Arr)[N])
233 : ArrayRef<T>(Arr) {}
235 T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
237 iterator begin() const { return data(); }
238 iterator end() const { return data() + this->size(); }
240 reverse_iterator rbegin() const { return reverse_iterator(end()); }
241 reverse_iterator rend() const { return reverse_iterator(begin()); }
243 /// front - Get the first element.
245 assert(!this->empty());
249 /// back - Get the last element.
251 assert(!this->empty());
252 return data()[this->size()-1];
255 /// slice(n) - Chop off the first N elements of the array.
256 MutableArrayRef<T> slice(unsigned N) const {
257 assert(N <= this->size() && "Invalid specifier");
258 return MutableArrayRef<T>(data()+N, this->size()-N);
261 /// slice(n, m) - Chop off the first N elements of the array, and keep M
262 /// elements in the array.
263 MutableArrayRef<T> slice(unsigned N, unsigned M) const {
264 assert(N+M <= this->size() && "Invalid specifier");
265 return MutableArrayRef<T>(data()+N, M);
269 /// @name Operator Overloads
271 T &operator[](size_t Index) const {
272 assert(Index < this->size() && "Invalid index!");
273 return data()[Index];
277 /// @name ArrayRef Convenience constructors
280 /// Construct an ArrayRef from a single element.
282 ArrayRef<T> makeArrayRef(const T &OneElt) {
286 /// Construct an ArrayRef from a pointer and length.
288 ArrayRef<T> makeArrayRef(const T *data, size_t length) {
289 return ArrayRef<T>(data, length);
292 /// Construct an ArrayRef from a range.
294 ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
295 return ArrayRef<T>(begin, end);
298 /// Construct an ArrayRef from a SmallVector.
299 template <typename T>
300 ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
304 /// Construct an ArrayRef from a SmallVector.
305 template <typename T, unsigned N>
306 ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
310 /// Construct an ArrayRef from a std::vector.
312 ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
316 /// Construct an ArrayRef from a C array.
317 template<typename T, size_t N>
318 ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
319 return ArrayRef<T>(Arr);
323 /// @name ArrayRef Comparison Operators
327 inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
328 return LHS.equals(RHS);
332 inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
333 return !(LHS == RHS);
338 // ArrayRefs can be treated like a POD type.
339 template <typename T> struct isPodLike;
340 template <typename T> struct isPodLike<ArrayRef<T> > {
341 static const bool value = true;