libpqxx  7.7.2
zview.hxx
1 /* Zero-terminated string view.
2  *
3  * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/zview instead.
4  *
5  * Copyright (c) 2000-2022, Jeroen T. Vermeulen.
6  *
7  * See COPYING for copyright license. If you did not receive a file called
8  * COPYING with this source code, please notify the distributor of this
9  * mistake, or contact the author.
10  */
11 #ifndef PQXX_H_ZVIEW
12 #define PQXX_H_ZVIEW
13 
14 #include <string>
15 #include <string_view>
16 #include <type_traits>
17 
18 #include "pqxx/types.hxx"
19 
20 
21 namespace pqxx
22 {
24 
37 class zview : public std::string_view
38 {
39 public:
40  constexpr zview() noexcept = default;
41 
43  constexpr zview(char const text[], std::ptrdiff_t len) :
44  std::string_view{text, static_cast<std::size_t>(len)}
45  {}
46 
48  constexpr zview(char text[], std::ptrdiff_t len) :
49  std::string_view{text, static_cast<std::size_t>(len)}
50  {}
51 
53  explicit constexpr zview(std::string_view other) noexcept :
54  std::string_view{other}
55  {}
56 
58 
60  template<typename... Args>
61  explicit constexpr zview(Args &&...args) :
62  std::string_view(std::forward<Args>(args)...)
63  {}
64 
65  // C++20: constexpr.
67  zview(std::string const &str) noexcept :
68  std::string_view{str.c_str(), str.size()}
69  {}
70 
72 
76  constexpr zview(char const str[]) : std::string_view{str} {}
77 
79 
87  template<size_t size>
88  constexpr zview(char const (&literal)[size]) : zview(literal, size - 1)
89  {}
90 
92  [[nodiscard]] constexpr char const *c_str() const &noexcept
93  {
94  return data();
95  }
96 };
97 
98 
100 
107 constexpr zview operator"" _zv(char const str[], std::size_t len) noexcept
108 {
109  return zview{str, len};
110 }
111 } // namespace pqxx
112 
113 
114 #if defined(PQXX_HAVE_CONCEPTS)
115 template<> inline constexpr bool std::ranges::enable_view<pqxx::zview>{true};
117 
118 
120 template<>
121 inline constexpr bool std::ranges::enable_borrowed_range<pqxx::zview>{true};
122 
123 namespace pqxx::internal
124 {
126 
130 template<typename T>
131 concept ZString = std::is_convertible_v < strip_t<T>,
132 char const * > or std::is_convertible_v<strip_t<T>, zview> or
133  std::is_convertible_v<T, std::string const &>;
134 } // namespace pqxx::internal
135 #endif // PQXX_HAVE_CONCEPTS
136 
137 
138 namespace pqxx::internal
139 {
141 inline constexpr char const *as_c_string(char const str[]) noexcept
142 {
143  return str;
144 }
146 template<std::size_t N>
147 inline constexpr char const *as_c_string(char (&str)[N]) noexcept
148 {
149  return str;
150 }
152 inline constexpr char const *as_c_string(pqxx::zview str) noexcept
153 {
154  return str.c_str();
155 }
156 // C++20: Make this constexpr.
158 inline char const *as_c_string(std::string const &str) noexcept
159 {
160  return str.c_str();
161 }
162 } // namespace pqxx::internal
163 #endif
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:26
constexpr zview() noexcept=default
constexpr zview(Args &&...args)
Construct from any initialiser you might use for std::string_view.
Definition: zview.hxx:61
STL namespace.
constexpr char const * as_c_string(char const str[]) noexcept
Get a raw C string pointer.
Definition: zview.hxx:141
zview(std::string const &str) noexcept
Definition: zview.hxx:67
constexpr zview(char const text[], std::ptrdiff_t len)
Convenience overload: construct using pointer and signed length.
Definition: zview.hxx:43
constexpr zview(std::string_view other) noexcept
Explicitly promote a string_view to a zview.
Definition: zview.hxx:53
Marker-type wrapper: zero-terminated std::string_view.
Definition: zview.hxx:37
Internal items for libpqxx&#39; own use. Do not use these yourself.
Definition: composite.hxx:82
constexpr zview(char text[], std::ptrdiff_t len)
Convenience overload: construct using pointer and signed length.
Definition: zview.hxx:48
constexpr char const * c_str() const &noexcept
Either a null pointer, or a zero-terminated text buffer.
Definition: zview.hxx:92
constexpr zview(char const (&literal)[size])
Construct a zview from a string literal.
Definition: zview.hxx:88
constexpr zview(char const str[])
Construct a zview from a C-style string.
Definition: zview.hxx:76