ArrayRef.h revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
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 "llvm/Support/Allocator.h"
16#include <vector>
17
18namespace llvm {
19
20  /// ArrayRef - Represent a constant reference to an array (0 or more elements
21  /// consecutively in memory), i.e. a start pointer and a length.  It allows
22  /// various APIs to take consecutive elements easily and conveniently.
23  ///
24  /// This class does not own the underlying data, it is expected to be used in
25  /// situations where the data resides in some other buffer, whose lifetime
26  /// extends past that of the ArrayRef. For this reason, it is not in general
27  /// safe to store an ArrayRef.
28  ///
29  /// This is intended to be trivially copyable, so it should be passed by
30  /// value.
31  template<typename T>
32  class ArrayRef {
33  public:
34    typedef const T *iterator;
35    typedef const T *const_iterator;
36    typedef size_t size_type;
37
38    typedef std::reverse_iterator<iterator> reverse_iterator;
39
40  private:
41    /// The start of the array, in an external buffer.
42    const T *Data;
43
44    /// The number of elements.
45    size_type Length;
46
47  public:
48    /// @name Constructors
49    /// @{
50
51    /// Construct an empty ArrayRef.
52    /*implicit*/ ArrayRef() : Data(0), Length(0) {}
53
54    /// Construct an empty ArrayRef from None.
55    /*implicit*/ ArrayRef(NoneType) : Data(0), Length(0) {}
56
57    /// Construct an ArrayRef from a single element.
58    /*implicit*/ ArrayRef(const T &OneElt)
59      : Data(&OneElt), Length(1) {}
60
61    /// Construct an ArrayRef from a pointer and length.
62    /*implicit*/ ArrayRef(const T *data, size_t length)
63      : Data(data), Length(length) {}
64
65    /// Construct an ArrayRef from a range.
66    ArrayRef(const T *begin, const T *end)
67      : Data(begin), Length(end - begin) {}
68
69    /// Construct an ArrayRef from a SmallVector. This is templated in order to
70    /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
71    /// copy-construct an ArrayRef.
72    template<typename U>
73    /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
74      : Data(Vec.data()), Length(Vec.size()) {
75    }
76
77    /// Construct an ArrayRef from a std::vector.
78    template<typename A>
79    /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
80      : Data(Vec.data()), Length(Vec.size()) {}
81
82    /// Construct an ArrayRef from a C array.
83    template <size_t N>
84    /*implicit*/ LLVM_CONSTEXPR ArrayRef(const T (&Arr)[N])
85      : Data(Arr), Length(N) {}
86
87#if LLVM_HAS_INITIALIZER_LISTS
88    /// Construct an ArrayRef from a std::initializer_list.
89    /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
90    : Data(Vec.begin() == Vec.end() ? (T*)0 : Vec.begin()),
91      Length(Vec.size()) {}
92#endif
93
94    /// @}
95    /// @name Simple Operations
96    /// @{
97
98    iterator begin() const { return Data; }
99    iterator end() const { return Data + Length; }
100
101    reverse_iterator rbegin() const { return reverse_iterator(end()); }
102    reverse_iterator rend() const { return reverse_iterator(begin()); }
103
104    /// empty - Check if the array is empty.
105    bool empty() const { return Length == 0; }
106
107    const T *data() const { return Data; }
108
109    /// size - Get the array size.
110    size_t size() const { return Length; }
111
112    /// front - Get the first element.
113    const T &front() const {
114      assert(!empty());
115      return Data[0];
116    }
117
118    /// back - Get the last element.
119    const T &back() const {
120      assert(!empty());
121      return Data[Length-1];
122    }
123
124    // copy - Allocate copy in BumpPtrAllocator and return ArrayRef<T> to it.
125    ArrayRef<T> copy(BumpPtrAllocator &Allocator) {
126      T *Buff = Allocator.Allocate<T>(Length);
127      std::copy(begin(), end(), Buff);
128      return ArrayRef<T>(Buff, Length);
129    }
130
131    /// equals - Check for element-wise equality.
132    bool equals(ArrayRef RHS) const {
133      if (Length != RHS.Length)
134        return false;
135      for (size_type i = 0; i != Length; i++)
136        if (Data[i] != RHS.Data[i])
137          return false;
138      return true;
139    }
140
141    /// slice(n) - Chop off the first N elements of the array.
142    ArrayRef<T> slice(unsigned N) const {
143      assert(N <= size() && "Invalid specifier");
144      return ArrayRef<T>(data()+N, size()-N);
145    }
146
147    /// slice(n, m) - Chop off the first N elements of the array, and keep M
148    /// elements in the array.
149    ArrayRef<T> slice(unsigned N, unsigned M) const {
150      assert(N+M <= size() && "Invalid specifier");
151      return ArrayRef<T>(data()+N, M);
152    }
153
154    /// @}
155    /// @name Operator Overloads
156    /// @{
157    const T &operator[](size_t Index) const {
158      assert(Index < Length && "Invalid index!");
159      return Data[Index];
160    }
161
162    /// @}
163    /// @name Expensive Operations
164    /// @{
165    std::vector<T> vec() const {
166      return std::vector<T>(Data, Data+Length);
167    }
168
169    /// @}
170    /// @name Conversion operators
171    /// @{
172    operator std::vector<T>() const {
173      return std::vector<T>(Data, Data+Length);
174    }
175
176    /// @}
177  };
178
179  /// MutableArrayRef - Represent a mutable reference to an array (0 or more
180  /// elements consecutively in memory), i.e. a start pointer and a length.  It
181  /// allows various APIs to take and modify consecutive elements easily and
182  /// conveniently.
183  ///
184  /// This class does not own the underlying data, it is expected to be used in
185  /// situations where the data resides in some other buffer, whose lifetime
186  /// extends past that of the MutableArrayRef. For this reason, it is not in
187  /// general safe to store a MutableArrayRef.
188  ///
189  /// This is intended to be trivially copyable, so it should be passed by
190  /// value.
191  template<typename T>
192  class MutableArrayRef : public ArrayRef<T> {
193  public:
194    typedef T *iterator;
195
196    typedef std::reverse_iterator<iterator> reverse_iterator;
197
198    /// Construct an empty MutableArrayRef.
199    /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
200
201    /// Construct an empty MutableArrayRef from None.
202    /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
203
204    /// Construct an MutableArrayRef from a single element.
205    /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
206
207    /// Construct an MutableArrayRef from a pointer and length.
208    /*implicit*/ MutableArrayRef(T *data, size_t length)
209      : ArrayRef<T>(data, length) {}
210
211    /// Construct an MutableArrayRef from a range.
212    MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
213
214    /// Construct an MutableArrayRef from a SmallVector.
215    /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
216    : ArrayRef<T>(Vec) {}
217
218    /// Construct a MutableArrayRef from a std::vector.
219    /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
220    : ArrayRef<T>(Vec) {}
221
222    /// Construct an MutableArrayRef from a C array.
223    template <size_t N>
224    /*implicit*/ MutableArrayRef(T (&Arr)[N])
225      : ArrayRef<T>(Arr) {}
226
227    T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
228
229    iterator begin() const { return data(); }
230    iterator end() const { return data() + this->size(); }
231
232    reverse_iterator rbegin() const { return reverse_iterator(end()); }
233    reverse_iterator rend() const { return reverse_iterator(begin()); }
234
235    /// front - Get the first element.
236    T &front() const {
237      assert(!this->empty());
238      return data()[0];
239    }
240
241    /// back - Get the last element.
242    T &back() const {
243      assert(!this->empty());
244      return data()[this->size()-1];
245    }
246
247    /// slice(n) - Chop off the first N elements of the array.
248    MutableArrayRef<T> slice(unsigned N) const {
249      assert(N <= this->size() && "Invalid specifier");
250      return MutableArrayRef<T>(data()+N, this->size()-N);
251    }
252
253    /// slice(n, m) - Chop off the first N elements of the array, and keep M
254    /// elements in the array.
255    MutableArrayRef<T> slice(unsigned N, unsigned M) const {
256      assert(N+M <= this->size() && "Invalid specifier");
257      return MutableArrayRef<T>(data()+N, M);
258    }
259
260    /// @}
261    /// @name Operator Overloads
262    /// @{
263    T &operator[](size_t Index) const {
264      assert(Index < this->size() && "Invalid index!");
265      return data()[Index];
266    }
267  };
268
269  /// @name ArrayRef Convenience constructors
270  /// @{
271
272  /// Construct an ArrayRef from a single element.
273  template<typename T>
274  ArrayRef<T> makeArrayRef(const T &OneElt) {
275    return OneElt;
276  }
277
278  /// Construct an ArrayRef from a pointer and length.
279  template<typename T>
280  ArrayRef<T> makeArrayRef(const T *data, size_t length) {
281    return ArrayRef<T>(data, length);
282  }
283
284  /// Construct an ArrayRef from a range.
285  template<typename T>
286  ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
287    return ArrayRef<T>(begin, end);
288  }
289
290  /// Construct an ArrayRef from a SmallVector.
291  template <typename T>
292  ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
293    return Vec;
294  }
295
296  /// Construct an ArrayRef from a SmallVector.
297  template <typename T, unsigned N>
298  ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
299    return Vec;
300  }
301
302  /// Construct an ArrayRef from a std::vector.
303  template<typename T>
304  ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
305    return Vec;
306  }
307
308  /// Construct an ArrayRef from a C array.
309  template<typename T, size_t N>
310  ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
311    return ArrayRef<T>(Arr);
312  }
313
314  /// @}
315  /// @name ArrayRef Comparison Operators
316  /// @{
317
318  template<typename T>
319  inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
320    return LHS.equals(RHS);
321  }
322
323  template<typename T>
324  inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
325    return !(LHS == RHS);
326  }
327
328  /// @}
329
330  // ArrayRefs can be treated like a POD type.
331  template <typename T> struct isPodLike;
332  template <typename T> struct isPodLike<ArrayRef<T> > {
333    static const bool value = true;
334  };
335}
336
337#endif
338