ArrayRef.h revision bc363931085587bac42a40653962a3e5acd1ffce 
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  private:
37    /// The start of the array, in an external buffer.
38    const T *Data;
39
40    /// The number of elements.
41    size_type Length;
42
43  public:
44    /// @name Constructors
45    /// @{
46
47    /// Construct an empty ArrayRef.
48    /*implicit*/ ArrayRef() : Data(0), Length(0) {}
49
50    /// Construct an ArrayRef from a single element.
51    /*implicit*/ ArrayRef(const T &OneElt)
52      : Data(&OneElt), Length(1) {}
53
54    /// Construct an ArrayRef from a pointer and length.
55    /*implicit*/ ArrayRef(const T *data, size_t length)
56      : Data(data), Length(length) {}
57
58    /// Construct an ArrayRef from a range.
59    ArrayRef(const T *begin, const T *end)
60      : Data(begin), Length(end - begin) {}
61
62    /// Construct an ArrayRef from a SmallVector. This is templated in order to
63    /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
64    /// copy-construct an ArrayRef.
65    template<typename U>
66    /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
67      : Data(Vec.data()), Length(Vec.size()) {
68    }
69
70    /// Construct an ArrayRef from a std::vector.
71    template<typename A>
72    /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
73      : Data(Vec.empty() ? (T*)0 : &Vec[0]), Length(Vec.size()) {}
74
75    /// Construct an ArrayRef from a C array.
76    template <size_t N>
77    /*implicit*/ ArrayRef(const T (&Arr)[N])
78      : Data(Arr), Length(N) {}
79
80    /// @}
81    /// @name Simple Operations
82    /// @{
83
84    iterator begin() const { return Data; }
85    iterator end() const { return Data + Length; }
86
87    /// empty - Check if the array is empty.
88    bool empty() const { return Length == 0; }
89
90    const T *data() const { return Data; }
91
92    /// size - Get the array size.
93    size_t size() const { return Length; }
94
95    /// front - Get the first element.
96    const T &front() const {
97      assert(!empty());
98      return Data[0];
99    }
100
101    /// back - Get the last element.
102    const T &back() const {
103      assert(!empty());
104      return Data[Length-1];
105    }
106
107    /// equals - Check for element-wise equality.
108    bool equals(ArrayRef RHS) const {
109      if (Length != RHS.Length)
110        return false;
111      for (size_type i = 0; i != Length; i++)
112        if (Data[i] != RHS.Data[i])
113          return false;
114      return true;
115    }
116
117    /// slice(n) - Chop off the first N elements of the array.
118    ArrayRef<T> slice(unsigned N) const {
119      assert(N <= size() && "Invalid specifier");
120      return ArrayRef<T>(data()+N, size()-N);
121    }
122
123    /// slice(n, m) - Chop off the first N elements of the array, and keep M
124    /// elements in the array.
125    ArrayRef<T> slice(unsigned N, unsigned M) const {
126      assert(N+M <= size() && "Invalid specifier");
127      return ArrayRef<T>(data()+N, M);
128    }
129
130    /// @}
131    /// @name Operator Overloads
132    /// @{
133    const T &operator[](size_t Index) const {
134      assert(Index < Length && "Invalid index!");
135      return Data[Index];
136    }
137
138    /// @}
139    /// @name Expensive Operations
140    /// @{
141    std::vector<T> vec() const {
142      return std::vector<T>(Data, Data+Length);
143    }
144
145    /// @}
146    /// @name Conversion operators
147    /// @{
148    operator std::vector<T>() const {
149      return std::vector<T>(Data, Data+Length);
150    }
151
152    /// @}
153  };
154
155  /// MutableArrayRef - Represent a mutable reference to an array (0 or more
156  /// elements consecutively in memory), i.e. a start pointer and a length.  It
157  /// allows various APIs to take and modify consecutive elements easily and
158  /// conveniently.
159  ///
160  /// This class does not own the underlying data, it is expected to be used in
161  /// situations where the data resides in some other buffer, whose lifetime
162  /// extends past that of the MutableArrayRef. For this reason, it is not in
163  /// general safe to store a MutableArrayRef.
164  ///
165  /// This is intended to be trivially copyable, so it should be passed by
166  /// value.
167  template<typename T>
168  class MutableArrayRef : public ArrayRef<T> {
169  public:
170    typedef T *iterator;
171
172    /// Construct an empty ArrayRef.
173    /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
174
175    /// Construct an MutableArrayRef from a single element.
176    /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
177
178    /// Construct an MutableArrayRef from a pointer and length.
179    /*implicit*/ MutableArrayRef(T *data, size_t length)
180      : ArrayRef<T>(data, length) {}
181
182    /// Construct an MutableArrayRef from a range.
183    MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
184
185    /// Construct an MutableArrayRef from a SmallVector.
186    /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
187    : ArrayRef<T>(Vec) {}
188
189    /// Construct a MutableArrayRef from a std::vector.
190    /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
191    : ArrayRef<T>(Vec) {}
192
193    /// Construct an MutableArrayRef from a C array.
194    template <size_t N>
195    /*implicit*/ MutableArrayRef(T (&Arr)[N])
196      : ArrayRef<T>(Arr) {}
197
198    T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
199
200    iterator begin() const { return data(); }
201    iterator end() const { return data() + this->size(); }
202
203    /// front - Get the first element.
204    T &front() const {
205      assert(!this->empty());
206      return data()[0];
207    }
208
209    /// back - Get the last element.
210    T &back() const {
211      assert(!this->empty());
212      return data()[this->size()-1];
213    }
214
215    /// slice(n) - Chop off the first N elements of the array.
216    MutableArrayRef<T> slice(unsigned N) const {
217      assert(N <= this->size() && "Invalid specifier");
218      return MutableArrayRef<T>(data()+N, this->size()-N);
219    }
220
221    /// slice(n, m) - Chop off the first N elements of the array, and keep M
222    /// elements in the array.
223    MutableArrayRef<T> slice(unsigned N, unsigned M) const {
224      assert(N+M <= this->size() && "Invalid specifier");
225      return MutableArrayRef<T>(data()+N, M);
226    }
227
228    /// @}
229    /// @name Operator Overloads
230    /// @{
231    T &operator[](size_t Index) const {
232      assert(Index < this->size() && "Invalid index!");
233      return data()[Index];
234    }
235  };
236
237  /// @name ArrayRef Convenience constructors
238  /// @{
239
240  /// Construct an ArrayRef from a single element.
241  template<typename T>
242  ArrayRef<T> makeArrayRef(const T &OneElt) {
243    return OneElt;
244  }
245
246  /// Construct an ArrayRef from a pointer and length.
247  template<typename T>
248  ArrayRef<T> makeArrayRef(const T *data, size_t length) {
249    return ArrayRef<T>(data, length);
250  }
251
252  /// Construct an ArrayRef from a range.
253  template<typename T>
254  ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
255    return ArrayRef<T>(begin, end);
256  }
257
258  /// Construct an ArrayRef from a SmallVector.
259  template <typename T>
260  ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
261    return Vec;
262  }
263
264  /// Construct an ArrayRef from a SmallVector.
265  template <typename T, unsigned N>
266  ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
267    return Vec;
268  }
269
270  /// Construct an ArrayRef from a std::vector.
271  template<typename T>
272  ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
273    return Vec;
274  }
275
276  /// Construct an ArrayRef from a C array.
277  template<typename T, size_t N>
278  ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
279    return ArrayRef<T>(Arr);
280  }
281
282  /// @}
283  /// @name ArrayRef Comparison Operators
284  /// @{
285
286  template<typename T>
287  inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
288    return LHS.equals(RHS);
289  }
290
291  template<typename T>
292  inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
293    return !(LHS == RHS);
294  }
295
296  /// @}
297
298  // ArrayRefs can be treated like a POD type.
299  template <typename T> struct isPodLike;
300  template <typename T> struct isPodLike<ArrayRef<T> > {
301    static const bool value = true;
302  };
303}
304
305#endif
306