1 //===----------------------- adt.h - Handy ADTs -----------------*- 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 // This file is a part of the ORC runtime support library.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef ORC_RT_ADT_H
14 #define ORC_RT_ADT_H
15 
16 #include <cstring>
17 #include <limits>
18 #include <ostream>
19 #include <string>
20 
21 namespace __orc_rt {
22 
23 constexpr std::size_t dynamic_extent = std::numeric_limits<std::size_t>::max();
24 
25 /// A substitute for std::span (and llvm::ArrayRef).
26 /// FIXME: Remove in favor of std::span once we can use c++20.
27 template <typename T, std::size_t Extent = dynamic_extent> class span {
28 public:
29   typedef T element_type;
30   typedef std::remove_cv<T> value_type;
31   typedef std::size_t size_type;
32   typedef std::ptrdiff_t difference_type;
33   typedef T *pointer;
34   typedef const T *const_pointer;
35   typedef T &reference;
36   typedef const T &const_reference;
37 
38   typedef pointer iterator;
39 
40   static constexpr std::size_t extent = Extent;
41 
42   constexpr span() noexcept = default;
43   constexpr span(T *first, size_type count) noexcept
44       : Data(first), Size(count) {}
45 
46   template <std::size_t N>
47   constexpr span(T (&arr)[N]) noexcept : Data(&arr[0]), Size(N) {}
48 
49   constexpr iterator begin() const noexcept { return Data; }
50   constexpr iterator end() const noexcept { return Data + Size; }
51   constexpr pointer data() const noexcept { return Data; }
52   constexpr reference operator[](size_type idx) const { return Data[idx]; }
53   constexpr size_type size() const noexcept { return Size; }
54   constexpr bool empty() const noexcept { return Size == 0; }
55 
56 private:
57   T *Data = nullptr;
58   size_type Size = 0;
59 };
60 
61 /// A substitue for std::string_view (and llvm::StringRef).
62 /// FIXME: Remove in favor of std::string_view once we have c++17.
63 class string_view {
64 public:
65   typedef char value_type;
66   typedef char *pointer;
67   typedef const char *const_pointer;
68   typedef char &reference;
69   typedef const char &const_reference;
70   typedef std::size_t size_type;
71   typedef std::ptrdiff_t difference_type;
72 
73   typedef const_pointer const_iterator;
74   typedef const_iterator iterator;
75 
76   constexpr string_view() noexcept = default;
77   constexpr string_view(const char *S, size_type Count)
78       : Data(S), Size(Count) {}
79   string_view(const char *S) : Data(S), Size(strlen(S)) {}
80   string_view(const std::string &S) : Data(S.data()), Size(S.size()) {}
81 
82   constexpr const_iterator begin() const noexcept { return Data; }
83   constexpr const_iterator end() const noexcept { return Data + Size; }
84   constexpr const_pointer data() const noexcept { return Data; }
85   constexpr const_reference operator[](size_type idx) { return Data[idx]; }
86   constexpr size_type size() const noexcept { return Size; }
87   constexpr bool empty() const noexcept { return Size == 0; }
88 
89   friend bool operator==(const string_view &LHS, const string_view &RHS) {
90     if (LHS.Size != RHS.Size)
91       return false;
92     if (LHS.Data == RHS.Data)
93       return true;
94     for (size_t I = 0; I != LHS.Size; ++I)
95       if (LHS.Data[I] != RHS.Data[I])
96         return false;
97     return true;
98   }
99 
100   friend bool operator!=(const string_view &LHS, const string_view &RHS) {
101     return !(LHS == RHS);
102   }
103 
104 private:
105   const char *Data = nullptr;
106   size_type Size = 0;
107 };
108 
109 inline std::ostream &operator<<(std::ostream &OS, string_view S) {
110   return OS.write(S.data(), S.size());
111 }
112 
113 } // end namespace __orc_rt
114 
115 namespace std {
116 // Make string_view hashable.
117 // FIXME: This can be removed (along with the string_view class) when we move
118 // to C++17.
119 template <> struct hash<__orc_rt::string_view> {
120   size_t operator()(const __orc_rt::string_view &S) const {
121     std::string Tmp(S.data(), S.size());
122     return hash<std::string>()(Tmp);
123   }
124 };
125 
126 } // namespace std
127 
128 #endif // ORC_RT_ADT_H
129