1//===--- ArrayRef.h - Array Reference Wrapper -------------------*- 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#ifndef LLVM_ADT_ARRAYREF_H
11#define LLVM_ADT_ARRAYREF_H
12
13#include "llvm/ADT/None.h"
14#include "llvm/ADT/SmallVector.h"
15#include <vector>
16
17namespace llvm {
18
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.
22  ///
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.
27  ///
28  /// This is intended to be trivially copyable, so it should be passed by
29  /// value.
30  template<typename T>
31  class ArrayRef {
32  public:
33    typedef const T *iterator;
34    typedef const T *const_iterator;
35    typedef size_t size_type;
36
37    typedef std::reverse_iterator<iterator> reverse_iterator;
38
39  private:
40    /// The start of the array, in an external buffer.
41    const T *Data;
42
43    /// The number of elements.
44    size_type Length;
45
46  public:
47    /// @name Constructors
48    /// @{
49
50    /// Construct an empty ArrayRef.
51    /*implicit*/ ArrayRef() : Data(nullptr), Length(0) {}
52
53    /// Construct an empty ArrayRef from None.
54    /*implicit*/ ArrayRef(NoneType) : Data(nullptr), Length(0) {}
55
56    /// Construct an ArrayRef from a single element.
57    /*implicit*/ ArrayRef(const T &OneElt)
58      : Data(&OneElt), Length(1) {}
59
60    /// Construct an ArrayRef from a pointer and length.
61    /*implicit*/ ArrayRef(const T *data, size_t length)
62      : Data(data), Length(length) {}
63
64    /// Construct an ArrayRef from a range.
65    ArrayRef(const T *begin, const T *end)
66      : Data(begin), Length(end - begin) {}
67
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.
71    template<typename U>
72    /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
73      : Data(Vec.data()), Length(Vec.size()) {
74    }
75
76    /// Construct an ArrayRef from a std::vector.
77    template<typename A>
78    /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
79      : Data(Vec.data()), Length(Vec.size()) {}
80
81    /// Construct an ArrayRef from a C array.
82    template <size_t N>
83    /*implicit*/ LLVM_CONSTEXPR ArrayRef(const T (&Arr)[N])
84      : Data(Arr), Length(N) {}
85
86#if LLVM_HAS_INITIALIZER_LISTS
87    /// Construct an ArrayRef from a std::initializer_list.
88    /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
89    : Data(Vec.begin() == Vec.end() ? (T*)0 : Vec.begin()),
90      Length(Vec.size()) {}
91#endif
92
93    /// @}
94    /// @name Simple Operations
95    /// @{
96
97    iterator begin() const { return Data; }
98    iterator end() const { return Data + Length; }
99
100    reverse_iterator rbegin() const { return reverse_iterator(end()); }
101    reverse_iterator rend() const { return reverse_iterator(begin()); }
102
103    /// empty - Check if the array is empty.
104    bool empty() const { return Length == 0; }
105
106    const T *data() const { return Data; }
107
108    /// size - Get the array size.
109    size_t size() const { return Length; }
110
111    /// front - Get the first element.
112    const T &front() const {
113      assert(!empty());
114      return Data[0];
115    }
116
117    /// back - Get the last element.
118    const T &back() const {
119      assert(!empty());
120      return Data[Length-1];
121    }
122
123    // copy - Allocate copy in Allocator and return ArrayRef<T> to it.
124    template <typename Allocator> ArrayRef<T> copy(Allocator &A) {
125      T *Buff = A.template Allocate<T>(Length);
126      std::copy(begin(), end(), Buff);
127      return ArrayRef<T>(Buff, Length);
128    }
129
130    /// equals - Check for element-wise equality.
131    bool equals(ArrayRef RHS) const {
132      if (Length != RHS.Length)
133        return false;
134      return std::equal(begin(), end(), RHS.begin());
135    }
136
137    /// slice(n) - Chop off the first N elements of the array.
138    ArrayRef<T> slice(unsigned N) const {
139      assert(N <= size() && "Invalid specifier");
140      return ArrayRef<T>(data()+N, size()-N);
141    }
142
143    /// slice(n, m) - Chop off the first N elements of the array, and keep M
144    /// elements in the array.
145    ArrayRef<T> slice(unsigned N, unsigned M) const {
146      assert(N+M <= size() && "Invalid specifier");
147      return ArrayRef<T>(data()+N, M);
148    }
149
150    // \brief Drop the last \p N elements of the array.
151    ArrayRef<T> drop_back(unsigned N = 1) const {
152      assert(size() >= N && "Dropping more elements than exist");
153      return slice(0, size() - N);
154    }
155
156    /// @}
157    /// @name Operator Overloads
158    /// @{
159    const T &operator[](size_t Index) const {
160      assert(Index < Length && "Invalid index!");
161      return Data[Index];
162    }
163
164    /// @}
165    /// @name Expensive Operations
166    /// @{
167    std::vector<T> vec() const {
168      return std::vector<T>(Data, Data+Length);
169    }
170
171    /// @}
172    /// @name Conversion operators
173    /// @{
174    operator std::vector<T>() const {
175      return std::vector<T>(Data, Data+Length);
176    }
177
178    /// @}
179  };
180
181  /// MutableArrayRef - Represent a mutable reference to an array (0 or more
182  /// elements consecutively in memory), i.e. a start pointer and a length.  It
183  /// allows various APIs to take and modify consecutive elements easily and
184  /// conveniently.
185  ///
186  /// This class does not own the underlying data, it is expected to be used in
187  /// situations where the data resides in some other buffer, whose lifetime
188  /// extends past that of the MutableArrayRef. For this reason, it is not in
189  /// general safe to store a MutableArrayRef.
190  ///
191  /// This is intended to be trivially copyable, so it should be passed by
192  /// value.
193  template<typename T>
194  class MutableArrayRef : public ArrayRef<T> {
195  public:
196    typedef T *iterator;
197
198    typedef std::reverse_iterator<iterator> reverse_iterator;
199
200    /// Construct an empty MutableArrayRef.
201    /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
202
203    /// Construct an empty MutableArrayRef from None.
204    /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
205
206    /// Construct an MutableArrayRef from a single element.
207    /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
208
209    /// Construct an MutableArrayRef from a pointer and length.
210    /*implicit*/ MutableArrayRef(T *data, size_t length)
211      : ArrayRef<T>(data, length) {}
212
213    /// Construct an MutableArrayRef from a range.
214    MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
215
216    /// Construct an MutableArrayRef from a SmallVector.
217    /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
218    : ArrayRef<T>(Vec) {}
219
220    /// Construct a MutableArrayRef from a std::vector.
221    /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
222    : ArrayRef<T>(Vec) {}
223
224    /// Construct an MutableArrayRef from a C array.
225    template <size_t N>
226    /*implicit*/ LLVM_CONSTEXPR MutableArrayRef(T (&Arr)[N])
227      : ArrayRef<T>(Arr) {}
228
229    T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
230
231    iterator begin() const { return data(); }
232    iterator end() const { return data() + this->size(); }
233
234    reverse_iterator rbegin() const { return reverse_iterator(end()); }
235    reverse_iterator rend() const { return reverse_iterator(begin()); }
236
237    /// front - Get the first element.
238    T &front() const {
239      assert(!this->empty());
240      return data()[0];
241    }
242
243    /// back - Get the last element.
244    T &back() const {
245      assert(!this->empty());
246      return data()[this->size()-1];
247    }
248
249    /// slice(n) - Chop off the first N elements of the array.
250    MutableArrayRef<T> slice(unsigned N) const {
251      assert(N <= this->size() && "Invalid specifier");
252      return MutableArrayRef<T>(data()+N, this->size()-N);
253    }
254
255    /// slice(n, m) - Chop off the first N elements of the array, and keep M
256    /// elements in the array.
257    MutableArrayRef<T> slice(unsigned N, unsigned M) const {
258      assert(N+M <= this->size() && "Invalid specifier");
259      return MutableArrayRef<T>(data()+N, M);
260    }
261
262    /// @}
263    /// @name Operator Overloads
264    /// @{
265    T &operator[](size_t Index) const {
266      assert(Index < this->size() && "Invalid index!");
267      return data()[Index];
268    }
269  };
270
271  /// @name ArrayRef Convenience constructors
272  /// @{
273
274  /// Construct an ArrayRef from a single element.
275  template<typename T>
276  ArrayRef<T> makeArrayRef(const T &OneElt) {
277    return OneElt;
278  }
279
280  /// Construct an ArrayRef from a pointer and length.
281  template<typename T>
282  ArrayRef<T> makeArrayRef(const T *data, size_t length) {
283    return ArrayRef<T>(data, length);
284  }
285
286  /// Construct an ArrayRef from a range.
287  template<typename T>
288  ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
289    return ArrayRef<T>(begin, end);
290  }
291
292  /// Construct an ArrayRef from a SmallVector.
293  template <typename T>
294  ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
295    return Vec;
296  }
297
298  /// Construct an ArrayRef from a SmallVector.
299  template <typename T, unsigned N>
300  ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
301    return Vec;
302  }
303
304  /// Construct an ArrayRef from a std::vector.
305  template<typename T>
306  ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
307    return Vec;
308  }
309
310  /// Construct an ArrayRef from a C array.
311  template<typename T, size_t N>
312  ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
313    return ArrayRef<T>(Arr);
314  }
315
316  /// @}
317  /// @name ArrayRef Comparison Operators
318  /// @{
319
320  template<typename T>
321  inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
322    return LHS.equals(RHS);
323  }
324
325  template<typename T>
326  inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
327    return !(LHS == RHS);
328  }
329
330  /// @}
331
332  // ArrayRefs can be treated like a POD type.
333  template <typename T> struct isPodLike;
334  template <typename T> struct isPodLike<ArrayRef<T> > {
335    static const bool value = true;
336  };
337}
338
339#endif
340