libsanitizer/sanitizer_common/sanitizer_array_ref.h

   1 //===-- sanitizer_array_ref.h -----------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef SANITIZER_ARRAY_REF_H
  10 #define SANITIZER_ARRAY_REF_H
  11
  12 #include "sanitizer_internal_defs.h"
  13
  14 namespace __sanitizer {
  15
  16 /// ArrayRef - Represent a constant reference to an array (0 or more elements
  17 /// consecutively in memory), i.e. a start pointer and a length.  It allows
  18 /// various APIs to take consecutive elements easily and conveniently.
  19 ///
  20 /// This class does not own the underlying data, it is expected to be used in
  21 /// situations where the data resides in some other buffer, whose lifetime
  22 /// extends past that of the ArrayRef. For this reason, it is not in general
  23 /// safe to store an ArrayRef.
  24 ///
  25 /// This is intended to be trivially copyable, so it should be passed by
  26 /// value.
  27 template <typename T>
  28 class ArrayRef {
  29  public:
  30   constexpr ArrayRef() {}
  31   constexpr ArrayRef(const T *begin, const T *end) : begin_(begin), end_(end) {
  32     DCHECK(empty() || begin);
  33   }
  34   constexpr ArrayRef(const T *data, uptr length)
  35       : ArrayRef(data, data + length) {}
  36   template <uptr N>
  37   constexpr ArrayRef(const T (&src)[N]) : ArrayRef(src, src + N) {}
  38   template <typename C>
  39   constexpr ArrayRef(const C &src)
  40       : ArrayRef(src.data(), src.data() + src.size()) {}
  41   ArrayRef(const T &one_elt) : ArrayRef(&one_elt, &one_elt + 1) {}
  42
  43   const T *data() const { return empty() ? nullptr : begin_; }
  44
  45   const T *begin() const { return begin_; }
  46   const T *end() const { return end_; }
  47
  48   bool empty() const { return begin_ == end_; }
  49
  50   uptr size() const { return end_ - begin_; }
  51
  52   /// equals - Check for element-wise equality.
  53   bool equals(ArrayRef rhs) const {
  54     if (size() != rhs.size())
  55       return false;
  56     auto r = rhs.begin();
  57     for (auto &l : *this) {
  58       if (!(l == *r))
  59         return false;
  60       ++r;
  61     }
  62     return true;
  63   }
  64
  65   /// slice(n, m) - Chop off the first N elements of the array, and keep M
  66   /// elements in the array.
  67   ArrayRef<T> slice(uptr N, uptr M) const {
  68     DCHECK_LE(N + M, size());
  69     return ArrayRef<T>(data() + N, M);
  70   }
  71
  72   /// slice(n) - Chop off the first N elements of the array.
  73   ArrayRef<T> slice(uptr N) const { return slice(N, size() - N); }
  74
  75   /// Drop the first \p N elements of the array.
  76   ArrayRef<T> drop_front(uptr N = 1) const {
  77     DCHECK_GE(size(), N);
  78     return slice(N, size() - N);
  79   }
  80
  81   /// Drop the last \p N elements of the array.
  82   ArrayRef<T> drop_back(uptr N = 1) const {
  83     DCHECK_GE(size(), N);
  84     return slice(0, size() - N);
  85   }
  86
  87   /// Return a copy of *this with only the first \p N elements.
  88   ArrayRef<T> take_front(uptr N = 1) const {
  89     if (N >= size())
  90       return *this;
  91     return drop_back(size() - N);
  92   }
  93
  94   /// Return a copy of *this with only the last \p N elements.
  95   ArrayRef<T> take_back(uptr N = 1) const {
  96     if (N >= size())
  97       return *this;
  98     return drop_front(size() - N);
  99   }
 100
 101   const T &operator[](uptr index) const {
 102     DCHECK_LT(index, size());
 103     return begin_[index];
 104   }
 105
 106  private:
 107   const T *begin_ = nullptr;
 108   const T *end_ = nullptr;
 109 };
 110
 111 template <typename T>
 112 inline bool operator==(ArrayRef<T> lhs, ArrayRef<T> rhs) {
 113   return lhs.equals(rhs);
 114 }
 115
 116 template <typename T>
 117 inline bool operator!=(ArrayRef<T> lhs, ArrayRef<T> rhs) {
 118   return !(lhs == rhs);
 119 }
 120
 121 }  // namespace __sanitizer
 122
 123 #endif  // SANITIZER_ARRAY_REF_H