libpqxx 7.7.0
row.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_ROW
14#define PQXX_H_ROW
15
16#include "pqxx/except.hxx"
17#include "pqxx/field.hxx"
18#include "pqxx/result.hxx"
19
20#include "pqxx/internal/concat.hxx"
21
22namespace pqxx::internal
23{
24template<typename... T> class result_iter;
25} // namespace pqxx::internal
26
27
28namespace pqxx
29{
31
42class PQXX_LIBEXPORT row
43{
44public:
53
54 row() = default;
55 row(row &&) = default;
56 row(row const &) = default;
57 row &operator=(row const &) = default;
58 row &operator=(row &&) = default;
59
64 [[nodiscard]] PQXX_PURE bool operator==(row const &) const noexcept;
65 [[nodiscard]] bool operator!=(row const &rhs) const noexcept
66 {
67 return not operator==(rhs);
68 }
70
71 [[nodiscard]] const_iterator begin() const noexcept;
72 [[nodiscard]] const_iterator cbegin() const noexcept;
73 [[nodiscard]] const_iterator end() const noexcept;
74 [[nodiscard]] const_iterator cend() const noexcept;
75
80 [[nodiscard]] reference front() const noexcept;
81 [[nodiscard]] reference back() const noexcept;
82
83 [[nodiscard]] const_reverse_row_iterator rbegin() const;
84 [[nodiscard]] const_reverse_row_iterator crbegin() const;
85 [[nodiscard]] const_reverse_row_iterator rend() const;
86 [[nodiscard]] const_reverse_row_iterator crend() const;
87
88 [[nodiscard]] reference operator[](size_type) const noexcept;
92 [[nodiscard]] reference operator[](zview col_name) const;
93
94 reference at(size_type) const;
98 reference at(zview col_name) const;
99
100 [[nodiscard]] size_type size() const noexcept { return m_end - m_begin; }
101
102 [[deprecated("Swap iterators, not rows.")]] void swap(row &) noexcept;
103
105 [[nodiscard]] result::size_type rownumber() const noexcept
106 {
107 return m_index;
108 }
109
115 [[nodiscard]] size_type column_number(zview col_name) const;
116
118 [[nodiscard]] oid column_type(size_type) const;
119
121 [[nodiscard]] oid column_type(zview col_name) const
122 {
123 return column_type(column_number(col_name));
124 }
125
127 [[nodiscard]] oid column_table(size_type col_num) const;
128
130 [[nodiscard]] oid column_table(zview col_name) const
131 {
132 return column_table(column_number(col_name));
133 }
134
136
143 [[nodiscard]] size_type table_column(size_type) const;
144
146 [[nodiscard]] size_type table_column(zview col_name) const
147 {
148 return table_column(column_number(col_name));
149 }
151
152 [[nodiscard]] result::size_type num() const { return rownumber(); }
153
165 [[deprecated("Row slicing is going away. File a bug if you need it.")]] row
166 slice(size_type sbegin, size_type send) const;
167
169 [[nodiscard, deprecated("Row slicing is going away.")]] PQXX_PURE bool
170 empty() const noexcept;
171
173
175 template<typename Tuple> void to(Tuple &t) const
176 {
177 check_size(std::tuple_size_v<Tuple>);
178 convert(t);
179 }
180
181 template<typename... TYPE> std::tuple<TYPE...> as() const
182 {
183 check_size(sizeof...(TYPE));
184 using seq = std::make_index_sequence<sizeof...(TYPE)>;
185 return get_tuple<std::tuple<TYPE...>>(seq{});
186 }
187
188protected:
189 friend class const_row_iterator;
190 friend class result;
191 row(result const &r, result_size_type index, size_type cols) noexcept;
192
194 void check_size(size_type expected) const
195 {
196 if (size() != expected)
197 throw usage_error{internal::concat(
198 "Tried to extract ", expected, " field(s) from a row of ", size(),
199 ".")};
200 }
201
202 template<typename... T> friend class pqxx::internal::result_iter;
204 template<typename Tuple> void convert(Tuple &t) const
205 {
206 // C++20: constinit.
207 constexpr auto tup_size{std::tuple_size_v<Tuple>};
208 extract_fields(t, std::make_index_sequence<tup_size>{});
209 }
210
211 friend class field;
212
215
217
221 result::size_type m_index = 0;
222
223 // TODO: Remove m_begin and (if possible) m_end when we remove slice().
225 size_type m_begin = 0;
227 size_type m_end = 0;
228
229private:
230 template<typename Tuple, std::size_t... indexes>
231 void extract_fields(Tuple &t, std::index_sequence<indexes...>) const
232 {
233 (extract_value<Tuple, indexes>(t), ...);
234 }
235
236 template<typename Tuple, std::size_t index>
237 void extract_value(Tuple &t) const;
238
240 template<typename TUPLE, std::size_t... indexes>
241 auto get_tuple(std::index_sequence<indexes...>) const
242 {
243 return std::make_tuple(get_field<TUPLE, indexes>()...);
244 }
245
247 template<typename TUPLE, std::size_t index> auto get_field() const
248 {
249 return (*this)[index].as<std::tuple_element_t<index, TUPLE>>();
250 }
251};
252
253
255class PQXX_LIBEXPORT const_row_iterator : public field
256{
257public:
258 using iterator_category = std::random_access_iterator_tag;
259 using value_type = field const;
260 using pointer = field const *;
264
265#include "pqxx/internal/ignore-deprecated-pre.hxx"
267#include "pqxx/internal/ignore-deprecated-post.hxx"
268 const_row_iterator(row const &t, row_size_type c) noexcept :
269 field{t.m_result, t.m_index, c}
270 {}
271 const_row_iterator(field const &F) noexcept : field{F} {}
274
279 [[nodiscard]] pointer operator->() const { return this; }
280 [[nodiscard]] reference operator*() const { return {*this}; }
282
289
290 const_row_iterator operator++(int);
292 {
293 ++m_col;
294 return *this;
295 }
296 const_row_iterator operator--(int);
298 {
299 --m_col;
300 return *this;
301 }
302
304 {
305 m_col = size_type(difference_type(m_col) + i);
306 return *this;
307 }
309 {
310 m_col = size_type(difference_type(m_col) - i);
311 return *this;
312 }
314
319 [[nodiscard]] bool operator==(const_row_iterator const &i) const
320 {
321 return col() == i.col();
322 }
323 [[nodiscard]] bool operator!=(const_row_iterator const &i) const
324 {
325 return col() != i.col();
326 }
327 [[nodiscard]] bool operator<(const_row_iterator const &i) const
328 {
329 return col() < i.col();
330 }
331 [[nodiscard]] bool operator<=(const_row_iterator const &i) const
332 {
333 return col() <= i.col();
334 }
335 [[nodiscard]] bool operator>(const_row_iterator const &i) const
336 {
337 return col() > i.col();
338 }
339 [[nodiscard]] bool operator>=(const_row_iterator const &i) const
340 {
341 return col() >= i.col();
342 }
344
349 [[nodiscard]] inline const_row_iterator operator+(difference_type) const;
350
351 friend const_row_iterator
352 operator+(difference_type, const_row_iterator const &);
353
354 [[nodiscard]] inline const_row_iterator operator-(difference_type) const;
355 [[nodiscard]] inline difference_type
356 operator-(const_row_iterator const &) const;
358};
359
360
362class PQXX_LIBEXPORT const_reverse_row_iterator : private const_row_iterator
363{
364public:
372
376
377 explicit const_reverse_row_iterator(super const &rhs) noexcept :
379 {
380 super::operator--();
381 }
382
383 [[nodiscard]] PQXX_PURE iterator_type base() const noexcept;
384
389 using iterator_type::operator->;
390 using iterator_type::operator*;
392
398 {
399 iterator_type::operator=(r);
400 return *this;
401 }
403 {
404 iterator_type::operator--();
405 return *this;
406 }
407 const_reverse_row_iterator operator++(int);
409 {
410 iterator_type::operator++();
411 return *this;
412 }
413 const_reverse_row_iterator operator--(int);
415 {
416 iterator_type::operator-=(i);
417 return *this;
418 }
420 {
421 iterator_type::operator+=(i);
422 return *this;
423 }
425
431 {
432 return const_reverse_row_iterator{base() - i};
433 }
435 {
436 return const_reverse_row_iterator{base() + i};
437 }
438 [[nodiscard]] difference_type
440 {
441 return rhs.const_row_iterator::operator-(*this);
442 }
444
449 [[nodiscard]] bool
450 operator==(const_reverse_row_iterator const &rhs) const noexcept
451 {
452 return iterator_type::operator==(rhs);
453 }
454 [[nodiscard]] bool
455 operator!=(const_reverse_row_iterator const &rhs) const noexcept
456 {
457 return !operator==(rhs);
458 }
459
460 [[nodiscard]] bool operator<(const_reverse_row_iterator const &rhs) const
461 {
462 return iterator_type::operator>(rhs);
463 }
464 [[nodiscard]] bool operator<=(const_reverse_row_iterator const &rhs) const
465 {
466 return iterator_type::operator>=(rhs);
467 }
468 [[nodiscard]] bool operator>(const_reverse_row_iterator const &rhs) const
469 {
470 return iterator_type::operator<(rhs);
471 }
472 [[nodiscard]] bool operator>=(const_reverse_row_iterator const &rhs) const
473 {
474 return iterator_type::operator<=(rhs);
475 }
477};
478
479
481{
482 // TODO:: More direct route to home().columns()?
483 return {
484 row{home(), idx(), home().columns()},
486}
487
490{
491 return i + o;
492}
493
496{
497 // TODO:: More direct route to home().columns()?
498 return {
499 row{home(), idx(), home().columns()},
501}
502
505{
506 return difference_type(num() - i.num());
507}
508
509
510template<typename Tuple, std::size_t index>
511inline void row::extract_value(Tuple &t) const
512{
513 using field_type = strip_t<decltype(std::get<index>(t))>;
514 field const f{m_result, m_index, index};
515 std::get<index>(t) = from_string<field_type>(f);
516}
517} // namespace pqxx
518#endif
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:23
const_row_iterator operator+(const_row_iterator::difference_type o, const_row_iterator const &i)
Definition: row.hxx:489
int row_size_type
Number of fields in a row of database data.
Definition: types.hxx:30
std::remove_cv_t< std::remove_reference_t< TYPE > > strip_t
Remove any constness, volatile, and reference-ness from a type.
Definition: types.hxx:87
int row_difference_type
Difference between row sizes.
Definition: types.hxx:33
int result_size_type
Number of rows in a result set.
Definition: types.hxx:24
Internal items for libpqxx' own use. Do not use these yourself.
Definition: composite.hxx:80
Error in usage of libpqxx library, similar to std::logic_error.
Definition: except.hxx:162
Reference to a field in a result set.
Definition: field.hxx:31
row_size_type col() const noexcept
Definition: field.hxx:255
field_size_type size_type
Definition: field.hxx:33
result::size_type idx() const noexcept
Definition: field.hxx:254
result const & home() const noexcept
Definition: field.hxx:253
PQXX_PURE row_size_type num() const
Return row number. The first row is row 0, the second is row 1, etc.
Definition: field.hxx:94
Result set containing data returned by a query or command.
Definition: result.hxx:68
PQXX_PURE row_size_type columns() const noexcept
Number of columns in result.
Definition: result.cxx:477
result_size_type size_type
Definition: result.hxx:70
Definition: row.hxx:24
Reference to one row in a result.
Definition: row.hxx:43
std::tuple< TYPE... > as() const
Definition: row.hxx:181
bool operator!=(row const &rhs) const noexcept
Definition: row.hxx:65
row(row &&)=default
row_size_type size_type
Definition: row.hxx:45
result::size_type rownumber() const noexcept
Row number, assuming this is a real row and not end()/rend().
Definition: row.hxx:105
result::size_type num() const
Definition: row.hxx:152
oid column_type(zview col_name) const
Return a column's type.
Definition: row.hxx:121
row_difference_type difference_type
Definition: row.hxx:46
row()=default
row & operator=(row const &)=default
result m_result
Result set of which this is one row.
Definition: row.hxx:214
result::size_type m_index
Row number.
Definition: row.hxx:221
row(row const &)=default
row & operator=(row &&)=default
void check_size(size_type expected) const
Throw usage_error if row size is not expected.
Definition: row.hxx:194
size_type table_column(zview col_name) const
What column number in its table did this result column come from?
Definition: row.hxx:146
void convert(Tuple &t) const
Convert entire row to tuple fields, without checking row size.
Definition: row.hxx:204
oid column_table(zview col_name) const
What table did this column come from?
Definition: row.hxx:130
Iterator for fields in a row. Use as row::const_iterator.
Definition: row.hxx:256
const_row_iterator & operator++()
Definition: row.hxx:291
bool operator>(const_row_iterator const &i) const
Definition: row.hxx:335
const_row_iterator(const_row_iterator const &)=default
bool operator==(const_row_iterator const &i) const
Definition: row.hxx:319
const_row_iterator(field const &F) noexcept
Definition: row.hxx:271
const_row_iterator & operator--()
Definition: row.hxx:297
std::random_access_iterator_tag iterator_category
Definition: row.hxx:258
const_row_iterator & operator-=(difference_type i)
Definition: row.hxx:308
const_row_iterator operator-(difference_type) const
Definition: row.hxx:495
field const * pointer
Definition: row.hxx:260
field const value_type
Definition: row.hxx:259
const_row_iterator operator+(difference_type) const
Definition: row.hxx:480
reference operator*() const
Definition: row.hxx:280
row_size_type size_type
Definition: row.hxx:261
bool operator!=(const_row_iterator const &i) const
Definition: row.hxx:323
bool operator>=(const_row_iterator const &i) const
Definition: row.hxx:339
row_difference_type difference_type
Definition: row.hxx:262
pointer operator->() const
Definition: row.hxx:279
const_row_iterator & operator=(const_row_iterator &&)=default
bool operator<=(const_row_iterator const &i) const
Definition: row.hxx:331
const_row_iterator(row const &t, row_size_type c) noexcept
Definition: row.hxx:268
const_row_iterator & operator+=(difference_type i)
Definition: row.hxx:303
const_row_iterator & operator=(const_row_iterator const &)=default
bool operator<(const_row_iterator const &i) const
Definition: row.hxx:327
const_row_iterator(const_row_iterator &&)=default
Reverse iterator for a row. Use as row::const_reverse_iterator.
Definition: row.hxx:363
const_reverse_row_iterator & operator+=(difference_type i)
Definition: row.hxx:414
bool operator!=(const_reverse_row_iterator const &rhs) const noexcept
Definition: row.hxx:455
const_reverse_row_iterator(const_reverse_row_iterator &&)=default
const_reverse_row_iterator & operator-=(difference_type i)
Definition: row.hxx:419
const_reverse_row_iterator operator+(difference_type i) const
Definition: row.hxx:430
const_reverse_row_iterator(super const &rhs) noexcept
Definition: row.hxx:377
bool operator>(const_reverse_row_iterator const &rhs) const
Definition: row.hxx:468
bool operator>=(const_reverse_row_iterator const &rhs) const
Definition: row.hxx:472
difference_type operator-(const_reverse_row_iterator const &rhs) const
Definition: row.hxx:439
const_reverse_row_iterator operator-(difference_type i)
Definition: row.hxx:434
bool operator<=(const_reverse_row_iterator const &rhs) const
Definition: row.hxx:464
bool operator==(const_reverse_row_iterator const &rhs) const noexcept
Definition: row.hxx:450
const_reverse_row_iterator & operator--()
Definition: row.hxx:408
const_reverse_row_iterator(const_reverse_row_iterator const &)=default
const_reverse_row_iterator operator++()
Definition: row.hxx:402
bool operator<(const_reverse_row_iterator const &rhs) const
Definition: row.hxx:460
Marker-type wrapper: zero-terminated std::string_view.
Definition: zview.hxx:38