ArrayRef.h revision 2f02ded68a114410f11bc2f4e901d0d8e5850de1 
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(0), Length(0) {}
52
53    /// Construct an empty ArrayRef from None.
54    /*implicit*/ ArrayRef(NoneType) : Data(0), 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.empty() ? (T*)0 : &Vec[0]), 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    /// @}
87    /// @name Simple Operations
88    /// @{
89
90    iterator begin() const { return Data; }
91    iterator end() const { return Data + Length; }
92
93    reverse_iterator rbegin() const { return reverse_iterator(end()); }
94    reverse_iterator rend() const { return reverse_iterator(begin()); }
95
96    /// empty - Check if the array is empty.
97    bool empty() const { return Length == 0; }
98
99    const T *data() const { return Data; }
100
101    /// size - Get the array size.
102    size_t size() const { return Length; }
103
104    /// front - Get the first element.
105    const T &front() const {
106      assert(!empty());
107      return Data[0];
108    }
109
110    /// back - Get the last element.
111    const T &back() const {
112      assert(!empty());
113      return Data[Length-1];
114    }
115
116    /// equals - Check for element-wise equality.
117    bool equals(ArrayRef RHS) const {
118      if (Length != RHS.Length)
119        return false;
120      for (size_type i = 0; i != Length; i++)
121        if (Data[i] != RHS.Data[i])
122          return false;
123      return true;
124    }
125
126    /// slice(n) - Chop off the first N elements of the array.
127    ArrayRef<T> slice(unsigned N) const {
128      assert(N <= size() && "Invalid specifier");
129      return ArrayRef<T>(data()+N, size()-N);
130    }
131
132    /// slice(n, m) - Chop off the first N elements of the array, and keep M
133    /// elements in the array.
134    ArrayRef<T> slice(unsigned N, unsigned M) const {
135      assert(N+M <= size() && "Invalid specifier");
136      return ArrayRef<T>(data()+N, M);
137    }
138
139    /// @}
140    /// @name Operator Overloads
141    /// @{
142    const T &operator[](size_t Index) const {
143      assert(Index < Length && "Invalid index!");
144      return Data[Index];
145    }
146
147    /// @}
148    /// @name Expensive Operations
149    /// @{
150    std::vector<T> vec() const {
151      return std::vector<T>(Data, Data+Length);
152    }
153
154    /// @}
155    /// @name Conversion operators
156    /// @{
157    operator std::vector<T>() const {
158      return std::vector<T>(Data, Data+Length);
159    }
160
161    /// @}
162  };
163
164  /// MutableArrayRef - Represent a mutable reference to an array (0 or more
165  /// elements consecutively in memory), i.e. a start pointer and a length.  It
166  /// allows various APIs to take and modify consecutive elements easily and
167  /// conveniently.
168  ///
169  /// This class does not own the underlying data, it is expected to be used in
170  /// situations where the data resides in some other buffer, whose lifetime
171  /// extends past that of the MutableArrayRef. For this reason, it is not in
172  /// general safe to store a MutableArrayRef.
173  ///
174  /// This is intended to be trivially copyable, so it should be passed by
175  /// value.
176  template<typename T>
177  class MutableArrayRef : public ArrayRef<T> {
178  public:
179    typedef T *iterator;
180
181    /// Construct an empty MutableArrayRef.
182    /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
183
184    /// Construct an empty MutableArrayRef from None.
185    /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
186
187    /// Construct an MutableArrayRef from a single element.
188    /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
189
190    /// Construct an MutableArrayRef from a pointer and length.
191    /*implicit*/ MutableArrayRef(T *data, size_t length)
192      : ArrayRef<T>(data, length) {}
193
194    /// Construct an MutableArrayRef from a range.
195    MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
196
197    /// Construct an MutableArrayRef from a SmallVector.
198    /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
199    : ArrayRef<T>(Vec) {}
200
201    /// Construct a MutableArrayRef from a std::vector.
202    /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
203    : ArrayRef<T>(Vec) {}
204
205    /// Construct an MutableArrayRef from a C array.
206    template <size_t N>
207    /*implicit*/ MutableArrayRef(T (&Arr)[N])
208      : ArrayRef<T>(Arr) {}
209
210    T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
211
212    iterator begin() const { return data(); }
213    iterator end() const { return data() + this->size(); }
214
215    /// front - Get the first element.
216    T &front() const {
217      assert(!this->empty());
218      return data()[0];
219    }
220
221    /// back - Get the last element.
222    T &back() const {
223      assert(!this->empty());
224      return data()[this->size()-1];
225    }
226
227    /// slice(n) - Chop off the first N elements of the array.
228    MutableArrayRef<T> slice(unsigned N) const {
229      assert(N <= this->size() && "Invalid specifier");
230      return MutableArrayRef<T>(data()+N, this->size()-N);
231    }
232
233    /// slice(n, m) - Chop off the first N elements of the array, and keep M
234    /// elements in the array.
235    MutableArrayRef<T> slice(unsigned N, unsigned M) const {
236      assert(N+M <= this->size() && "Invalid specifier");
237      return MutableArrayRef<T>(data()+N, M);
238    }
239
240    /// @}
241    /// @name Operator Overloads
242    /// @{
243    T &operator[](size_t Index) const {
244      assert(Index < this->size() && "Invalid index!");
245      return data()[Index];
246    }
247  };
248
249  /// @name ArrayRef Convenience constructors
250  /// @{
251
252  /// Construct an ArrayRef from a single element.
253  template<typename T>
254  ArrayRef<T> makeArrayRef(const T &OneElt) {
255    return OneElt;
256  }
257
258  /// Construct an ArrayRef from a pointer and length.
259  template<typename T>
260  ArrayRef<T> makeArrayRef(const T *data, size_t length) {
261    return ArrayRef<T>(data, length);
262  }
263
264  /// Construct an ArrayRef from a range.
265  template<typename T>
266  ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
267    return ArrayRef<T>(begin, end);
268  }
269
270  /// Construct an ArrayRef from a SmallVector.
271  template <typename T>
272  ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
273    return Vec;
274  }
275
276  /// Construct an ArrayRef from a SmallVector.
277  template <typename T, unsigned N>
278  ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
279    return Vec;
280  }
281
282  /// Construct an ArrayRef from a std::vector.
283  template<typename T>
284  ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
285    return Vec;
286  }
287
288  /// Construct an ArrayRef from a C array.
289  template<typename T, size_t N>
290  ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
291    return ArrayRef<T>(Arr);
292  }
293
294  /// @}
295  /// @name ArrayRef Comparison Operators
296  /// @{
297
298  template<typename T>
299  inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
300    return LHS.equals(RHS);
301  }
302
303  template<typename T>
304  inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
305    return !(LHS == RHS);
306  }
307
308  /// @}
309
310  // ArrayRefs can be treated like a POD type.
311  template <typename T> struct isPodLike;
312  template <typename T> struct isPodLike<ArrayRef<T> > {
313    static const bool value = true;
314  };
315}
316
317#endif
318