ArrayRef.h revision 827de0520ee986fcda5f0d3290a3746249fa5847 
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/SmallVector.h"
14#include <vector>
15
16namespace llvm {
17
18  /// ArrayRef - Represent a constant reference to an array (0 or more elements
19  /// consecutively in memory), i.e. a start pointer and a length.  It allows
20  /// various APIs to take consecutive elements easily and conveniently.
21  ///
22  /// This class does not own the underlying data, it is expected to be used in
23  /// situations where the data resides in some other buffer, whose lifetime
24  /// extends past that of the ArrayRef. For this reason, it is not in general
25  /// safe to store an ArrayRef.
26  ///
27  /// This is intended to be trivially copyable, so it should be passed by
28  /// value.
29  template<typename T>
30  class ArrayRef {
31  public:
32    typedef const T *iterator;
33    typedef const T *const_iterator;
34    typedef size_t size_type;
35
36    typedef std::reverse_iterator<iterator> reverse_iterator;
37
38  private:
39    /// The start of the array, in an external buffer.
40    const T *Data;
41
42    /// The number of elements.
43    size_type Length;
44
45  public:
46    /// @name Constructors
47    /// @{
48
49    /// Construct an empty ArrayRef.
50    /*implicit*/ ArrayRef() : Data(0), Length(0) {}
51
52    /// Construct an ArrayRef from a single element.
53    /*implicit*/ ArrayRef(const T &OneElt)
54      : Data(&OneElt), Length(1) {}
55
56    /// Construct an ArrayRef from a pointer and length.
57    /*implicit*/ ArrayRef(const T *data, size_t length)
58      : Data(data), Length(length) {}
59
60    /// Construct an ArrayRef from a range.
61    ArrayRef(const T *begin, const T *end)
62      : Data(begin), Length(end - begin) {}
63
64    /// Construct an ArrayRef from a SmallVector. This is templated in order to
65    /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
66    /// copy-construct an ArrayRef.
67    template<typename U>
68    /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
69      : Data(Vec.data()), Length(Vec.size()) {
70    }
71
72    /// Construct an ArrayRef from a std::vector.
73    template<typename A>
74    /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
75      : Data(Vec.empty() ? (T*)0 : &Vec[0]), Length(Vec.size()) {}
76
77    /// Construct an ArrayRef from a C array.
78    template <size_t N>
79    /*implicit*/ ArrayRef(const T (&Arr)[N])
80      : Data(Arr), Length(N) {}
81
82    /// @}
83    /// @name Simple Operations
84    /// @{
85
86    iterator begin() const { return Data; }
87    iterator end() const { return Data + Length; }
88
89    reverse_iterator rbegin() const { return reverse_iterator(end()); }
90    reverse_iterator rend() const { return reverse_iterator(begin()); }
91
92    /// empty - Check if the array is empty.
93    bool empty() const { return Length == 0; }
94
95    const T *data() const { return Data; }
96
97    /// size - Get the array size.
98    size_t size() const { return Length; }
99
100    /// front - Get the first element.
101    const T &front() const {
102      assert(!empty());
103      return Data[0];
104    }
105
106    /// back - Get the last element.
107    const T &back() const {
108      assert(!empty());
109      return Data[Length-1];
110    }
111
112    /// equals - Check for element-wise equality.
113    bool equals(ArrayRef RHS) const {
114      if (Length != RHS.Length)
115        return false;
116      for (size_type i = 0; i != Length; i++)
117        if (Data[i] != RHS.Data[i])
118          return false;
119      return true;
120    }
121
122    /// slice(n) - Chop off the first N elements of the array.
123    ArrayRef<T> slice(unsigned N) const {
124      assert(N <= size() && "Invalid specifier");
125      return ArrayRef<T>(data()+N, size()-N);
126    }
127
128    /// slice(n, m) - Chop off the first N elements of the array, and keep M
129    /// elements in the array.
130    ArrayRef<T> slice(unsigned N, unsigned M) const {
131      assert(N+M <= size() && "Invalid specifier");
132      return ArrayRef<T>(data()+N, M);
133    }
134
135    /// @}
136    /// @name Operator Overloads
137    /// @{
138    const T &operator[](size_t Index) const {
139      assert(Index < Length && "Invalid index!");
140      return Data[Index];
141    }
142
143    /// @}
144    /// @name Expensive Operations
145    /// @{
146    std::vector<T> vec() const {
147      return std::vector<T>(Data, Data+Length);
148    }
149
150    /// @}
151    /// @name Conversion operators
152    /// @{
153    operator std::vector<T>() const {
154      return std::vector<T>(Data, Data+Length);
155    }
156
157    /// @}
158  };
159
160  /// MutableArrayRef - Represent a mutable reference to an array (0 or more
161  /// elements consecutively in memory), i.e. a start pointer and a length.  It
162  /// allows various APIs to take and modify consecutive elements easily and
163  /// conveniently.
164  ///
165  /// This class does not own the underlying data, it is expected to be used in
166  /// situations where the data resides in some other buffer, whose lifetime
167  /// extends past that of the MutableArrayRef. For this reason, it is not in
168  /// general safe to store a MutableArrayRef.
169  ///
170  /// This is intended to be trivially copyable, so it should be passed by
171  /// value.
172  template<typename T>
173  class MutableArrayRef : public ArrayRef<T> {
174  public:
175    typedef T *iterator;
176
177    /// Construct an empty ArrayRef.
178    /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
179
180    /// Construct an MutableArrayRef from a single element.
181    /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
182
183    /// Construct an MutableArrayRef from a pointer and length.
184    /*implicit*/ MutableArrayRef(T *data, size_t length)
185      : ArrayRef<T>(data, length) {}
186
187    /// Construct an MutableArrayRef from a range.
188    MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
189
190    /// Construct an MutableArrayRef from a SmallVector.
191    /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
192    : ArrayRef<T>(Vec) {}
193
194    /// Construct a MutableArrayRef from a std::vector.
195    /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
196    : ArrayRef<T>(Vec) {}
197
198    /// Construct an MutableArrayRef from a C array.
199    template <size_t N>
200    /*implicit*/ MutableArrayRef(T (&Arr)[N])
201      : ArrayRef<T>(Arr) {}
202
203    T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
204
205    iterator begin() const { return data(); }
206    iterator end() const { return data() + this->size(); }
207
208    /// front - Get the first element.
209    T &front() const {
210      assert(!this->empty());
211      return data()[0];
212    }
213
214    /// back - Get the last element.
215    T &back() const {
216      assert(!this->empty());
217      return data()[this->size()-1];
218    }
219
220    /// slice(n) - Chop off the first N elements of the array.
221    MutableArrayRef<T> slice(unsigned N) const {
222      assert(N <= this->size() && "Invalid specifier");
223      return MutableArrayRef<T>(data()+N, this->size()-N);
224    }
225
226    /// slice(n, m) - Chop off the first N elements of the array, and keep M
227    /// elements in the array.
228    MutableArrayRef<T> slice(unsigned N, unsigned M) const {
229      assert(N+M <= this->size() && "Invalid specifier");
230      return MutableArrayRef<T>(data()+N, M);
231    }
232
233    /// @}
234    /// @name Operator Overloads
235    /// @{
236    T &operator[](size_t Index) const {
237      assert(Index < this->size() && "Invalid index!");
238      return data()[Index];
239    }
240  };
241
242  /// @name ArrayRef Convenience constructors
243  /// @{
244
245  /// Construct an ArrayRef from a single element.
246  template<typename T>
247  ArrayRef<T> makeArrayRef(const T &OneElt) {
248    return OneElt;
249  }
250
251  /// Construct an ArrayRef from a pointer and length.
252  template<typename T>
253  ArrayRef<T> makeArrayRef(const T *data, size_t length) {
254    return ArrayRef<T>(data, length);
255  }
256
257  /// Construct an ArrayRef from a range.
258  template<typename T>
259  ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
260    return ArrayRef<T>(begin, end);
261  }
262
263  /// Construct an ArrayRef from a SmallVector.
264  template <typename T>
265  ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
266    return Vec;
267  }
268
269  /// Construct an ArrayRef from a SmallVector.
270  template <typename T, unsigned N>
271  ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
272    return Vec;
273  }
274
275  /// Construct an ArrayRef from a std::vector.
276  template<typename T>
277  ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
278    return Vec;
279  }
280
281  /// Construct an ArrayRef from a C array.
282  template<typename T, size_t N>
283  ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
284    return ArrayRef<T>(Arr);
285  }
286
287  /// @}
288  /// @name ArrayRef Comparison Operators
289  /// @{
290
291  template<typename T>
292  inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
293    return LHS.equals(RHS);
294  }
295
296  template<typename T>
297  inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
298    return !(LHS == RHS);
299  }
300
301  /// @}
302
303  // ArrayRefs can be treated like a POD type.
304  template <typename T> struct isPodLike;
305  template <typename T> struct isPodLike<ArrayRef<T> > {
306    static const bool value = true;
307  };
308}
309
310#endif
311