libpqxx  7.7.1
result.hxx
1 /* Definitions for the pqxx::result class and support classes.
2  *
3  * pqxx::result represents the set of result rows from a database query.
4  *
5  * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/result instead.
6  *
7  * Copyright (c) 2000-2022, Jeroen T. Vermeulen.
8  *
9  * See COPYING for copyright license. If you did not receive a file called
10  * COPYING with this source code, please notify the distributor of this
11  * mistake, or contact the author.
12  */
13 #ifndef PQXX_H_RESULT
14 #define PQXX_H_RESULT
15 
16 #if !defined(PQXX_HEADER_PRE)
17 # error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
18 #endif
19 
20 #include <ios>
21 #include <memory>
22 #include <stdexcept>
23 
24 #include "pqxx/except.hxx"
25 #include "pqxx/types.hxx"
26 #include "pqxx/util.hxx"
27 #include "pqxx/zview.hxx"
28 
29 #include "pqxx/internal/encodings.hxx"
30 
31 
32 namespace pqxx::internal
33 {
34 // TODO: Make noexcept (but breaks ABI).
35 PQXX_LIBEXPORT void clear_result(pq::PGresult const *);
36 } // namespace pqxx::internal
37 
38 
39 namespace pqxx::internal::gate
40 {
41 class result_connection;
42 class result_creation;
43 class result_pipeline;
44 class result_row;
45 class result_sql_cursor;
46 } // namespace pqxx::internal::gate
47 
48 
49 namespace pqxx
50 {
52 
72 class PQXX_LIBEXPORT result
73 {
74 public:
77  using reference = row;
78  using const_iterator = const_result_iterator;
81  using const_reverse_iterator = const_reverse_result_iterator;
83 
84  result() noexcept :
85  m_data{make_data_pointer()},
86  m_query{},
87  m_encoding{internal::encoding_group::MONOBYTE}
88  {}
89 
90  result(result const &rhs) noexcept = default;
91  result(result &&rhs) noexcept = default;
92 
94 
97  result &operator=(result const &rhs) noexcept = default;
98 
100  result &operator=(result &&rhs) noexcept = default;
101 
110  [[nodiscard]] bool operator==(result const &) const noexcept;
113  [[nodiscard]] bool operator!=(result const &rhs) const noexcept
114  {
115  return not operator==(rhs);
116  }
118 
120 
126  template<typename... TYPE> auto iter() const;
127 
128  [[nodiscard]] const_reverse_iterator rbegin() const;
129  [[nodiscard]] const_reverse_iterator crbegin() const;
130  [[nodiscard]] const_reverse_iterator rend() const;
131  [[nodiscard]] const_reverse_iterator crend() const;
132 
133  [[nodiscard]] const_iterator begin() const noexcept;
134  [[nodiscard]] const_iterator cbegin() const noexcept;
135  [[nodiscard]] inline const_iterator end() const noexcept;
136  [[nodiscard]] inline const_iterator cend() const noexcept;
137 
138  [[nodiscard]] reference front() const noexcept;
139  [[nodiscard]] reference back() const noexcept;
140 
141  [[nodiscard]] PQXX_PURE size_type size() const noexcept;
142  [[nodiscard]] PQXX_PURE bool empty() const noexcept;
143  [[nodiscard]] size_type capacity() const noexcept { return size(); }
144 
146 
150  void swap(result &) noexcept;
151 
153 
157  [[nodiscard]] row operator[](size_type i) const noexcept;
158 
159 #if defined(PQXX_HAVE_MULTIDIMENSIONAL_SUBSCRIPT)
160  [[nodiscard]] field
161  operator[](size_type row_num, row_size_type col_num) const noexcept;
162 #endif
163 
165  row at(size_type) const;
166 
168  field at(size_type, row_size_type) const;
169 
171 
178  void clear() noexcept
179  {
180  m_data.reset();
181  m_query = nullptr;
182  }
183 
188  [[nodiscard]] PQXX_PURE row_size_type columns() const noexcept;
190 
192  [[nodiscard]] row_size_type column_number(zview name) const;
193 
195  [[nodiscard]] char const *column_name(row_size_type number) const &;
196 
198  [[nodiscard]] oid column_type(row_size_type col_num) const;
199 
201  [[nodiscard]] oid column_type(zview col_name) const
202  {
203  return column_type(column_number(col_name));
204  }
205 
207  [[nodiscard]] oid column_table(row_size_type col_num) const;
208 
210  [[nodiscard]] oid column_table(zview col_name) const
211  {
212  return column_table(column_number(col_name));
213  }
214 
216  [[nodiscard]] row_size_type table_column(row_size_type col_num) const;
217 
219  [[nodiscard]] row_size_type table_column(zview col_name) const
220  {
221  return table_column(column_number(col_name));
222  }
224 
226  [[nodiscard]] PQXX_PURE std::string const &query() const &noexcept;
227 
229 
232  [[nodiscard]] PQXX_PURE oid inserted_oid() const;
233 
235 
238  [[nodiscard]] PQXX_PURE size_type affected_rows() const;
239 
240 
241 private:
242  using data_pointer = std::shared_ptr<internal::pq::PGresult const>;
243 
245  data_pointer m_data;
246 
248  static data_pointer
249  make_data_pointer(internal::pq::PGresult const *res = nullptr) noexcept
250  {
251  return {res, internal::clear_result};
252  }
253 
254  friend class pqxx::internal::gate::result_pipeline;
255  PQXX_PURE std::shared_ptr<std::string const> query_ptr() const noexcept
256  {
257  return m_query;
258  }
259 
261  std::shared_ptr<std::string const> m_query;
262 
263  internal::encoding_group m_encoding;
264 
265  static std::string const s_empty_string;
266 
267  friend class pqxx::field;
268  // TODO: noexcept. Breaks ABI.
269  PQXX_PURE char const *get_value(size_type row, row_size_type col) const;
270  // TODO: noexcept. Breaks ABI.
271  PQXX_PURE bool get_is_null(size_type row, row_size_type col) const;
272  PQXX_PURE
273  field_size_type get_length(size_type, row_size_type) const noexcept;
274 
275  friend class pqxx::internal::gate::result_creation;
276  result(
277  internal::pq::PGresult *rhs, std::shared_ptr<std::string> query,
278  internal::encoding_group enc);
279 
280  PQXX_PRIVATE void check_status(std::string_view desc = ""sv) const;
281 
282  friend class pqxx::internal::gate::result_connection;
283  friend class pqxx::internal::gate::result_row;
284  bool operator!() const noexcept { return m_data.get() == nullptr; }
285  operator bool() const noexcept { return m_data.get() != nullptr; }
286 
287  [[noreturn]] PQXX_PRIVATE void
288  throw_sql_error(std::string const &Err, std::string const &Query) const;
289  PQXX_PRIVATE PQXX_PURE int errorposition() const;
290  PQXX_PRIVATE std::string status_error() const;
291 
292  friend class pqxx::internal::gate::result_sql_cursor;
293  PQXX_PURE char const *cmd_status() const noexcept;
294 };
295 } // namespace pqxx
296 #endif
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:26
Reference to one row in a result.
Definition: row.hxx:46
void clear_result(pq::PGresult const *)
C++ wrapper for libpq&#39;s PQclear.
Definition: result.cxx:42
row_size_type table_column(zview col_name) const
What column in its table did this column come from?
Definition: result.hxx:219
const_result_iterator const_iterator
Definition: result.hxx:78
Reference to a field in a result set.
Definition: field.hxx:34
std::size_t field_size_type
Number of bytes in a field of database data.
Definition: types.hxx:40
int row_size_type
Number of fields in a row of database data.
Definition: types.hxx:34
size_type capacity() const noexcept
Definition: result.hxx:143
result() noexcept
Definition: result.hxx:84
result_difference_type difference_type
Definition: result.hxx:76
Definition: connection.hxx:99
bool operator!=(result const &rhs) const noexcept
Compare two results for inequality.
Definition: result.hxx:113
const_reverse_result_iterator const_reverse_iterator
Definition: result.hxx:81
result_size_type size_type
Definition: result.hxx:75
oid column_type(zview col_name) const
Return column&#39;s type, as an OID from the system catalogue.
Definition: result.hxx:201
const_iterator iterator
Definition: result.hxx:80
constexpr row_size_type col() const noexcept
Definition: field.hxx:265
Result set containing data returned by a query or command.
Definition: result.hxx:72
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
void clear() noexcept
Let go of the result&#39;s data.
Definition: result.hxx:178
oid column_table(zview col_name) const
What table did this column come from?
Definition: result.hxx:210
const_reverse_iterator reverse_iterator
Definition: result.hxx:82
int result_difference_type
Difference between result sizes.
Definition: types.hxx:31
int result_size_type
Number of rows in a result set.
Definition: types.hxx:28
const_iterator pointer
Definition: result.hxx:79