libpqxx 7.8.1
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) 2000-2023, 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#if !defined(PQXX_HEADER_PRE)
17# error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
18#endif
19
20#include "pqxx/except.hxx"
21#include "pqxx/field.hxx"
22#include "pqxx/result.hxx"
23
24#include "pqxx/internal/concat.hxx"
25
26namespace pqxx::internal
27{
28template<typename... T> class result_iter;
29} // namespace pqxx::internal
30
31
32namespace pqxx
33{
35
46class PQXX_LIBEXPORT row
47{
48public:
57
58 row() noexcept = default;
59 row(row &&) noexcept = default;
60 row(row const &) noexcept = default;
61 row &operator=(row const &) noexcept = default;
62 row &operator=(row &&) noexcept = default;
63
68 [[nodiscard]] PQXX_PURE bool operator==(row const &) const noexcept;
69 [[nodiscard]] bool operator!=(row const &rhs) const noexcept
70 {
71 return not operator==(rhs);
72 }
74
75 [[nodiscard]] const_iterator begin() const noexcept;
76 [[nodiscard]] const_iterator cbegin() const noexcept;
77 [[nodiscard]] const_iterator end() const noexcept;
78 [[nodiscard]] const_iterator cend() const noexcept;
79
84 [[nodiscard]] reference front() const noexcept;
85 [[nodiscard]] reference back() const noexcept;
86
87 [[nodiscard]] const_reverse_row_iterator rbegin() const noexcept;
88 [[nodiscard]] const_reverse_row_iterator crbegin() const noexcept;
89 [[nodiscard]] const_reverse_row_iterator rend() const noexcept;
90 [[nodiscard]] const_reverse_row_iterator crend() const noexcept;
91
92 [[nodiscard]] reference operator[](size_type) const noexcept;
96 [[nodiscard]] reference operator[](zview col_name) const;
97
98 reference at(size_type) const;
102 reference at(zview col_name) const;
103
104 [[nodiscard]] constexpr size_type size() const noexcept
105 {
106 return m_end - m_begin;
107 }
108
109 [[deprecated("Swap iterators, not rows.")]] void swap(row &) noexcept;
110
112 [[nodiscard]] constexpr result::size_type rownumber() const noexcept
113 {
114 return m_index;
115 }
116
122 [[nodiscard]] size_type column_number(zview col_name) const;
123
125 [[nodiscard]] oid column_type(size_type) const;
126
128 [[nodiscard]] oid column_type(zview col_name) const
129 {
130 return column_type(column_number(col_name));
131 }
132
134 [[nodiscard]] oid column_table(size_type col_num) const;
135
137 [[nodiscard]] oid column_table(zview col_name) const
138 {
139 return column_table(column_number(col_name));
140 }
141
143
150 [[nodiscard]] size_type table_column(size_type) const;
151
153 [[nodiscard]] size_type table_column(zview col_name) const
154 {
155 return table_column(column_number(col_name));
156 }
158
159 [[nodiscard]] constexpr result::size_type num() const noexcept
160 {
161 return rownumber();
162 }
163
175 [[deprecated("Row slicing is going away. File a bug if you need it.")]] row
176 slice(size_type sbegin, size_type send) const;
177
179 [[nodiscard, deprecated("Row slicing is going away.")]] PQXX_PURE bool
180 empty() const noexcept;
181
183
188 template<typename Tuple> void to(Tuple &t) const
189 {
190 check_size(std::tuple_size_v<Tuple>);
191 convert(t);
192 }
193
195
200 template<typename... TYPE> std::tuple<TYPE...> as() const
201 {
202 check_size(sizeof...(TYPE));
203 using seq = std::make_index_sequence<sizeof...(TYPE)>;
204 return get_tuple<std::tuple<TYPE...>>(seq{});
205 }
206
207protected:
208 friend class const_row_iterator;
209 friend class result;
210 row(result const &r, result_size_type index, size_type cols) noexcept;
211
213 void check_size(size_type expected) const
214 {
215 if (size() != expected)
216 throw usage_error{internal::concat(
217 "Tried to extract ", expected, " field(s) from a row of ", size(),
218 ".")};
219 }
220
222
225 template<typename TUPLE> TUPLE as_tuple() const
226 {
227 using seq = std::make_index_sequence<std::tuple_size_v<TUPLE>>;
228 return get_tuple<TUPLE>(seq{});
229 }
230
231 template<typename... T> friend class pqxx::internal::result_iter;
233 template<typename Tuple> void convert(Tuple &t) const
234 {
235 extract_fields(t, std::make_index_sequence<std::tuple_size_v<Tuple>>{});
236 }
237
238 friend class field;
239
242
244
248 result::size_type m_index = 0;
249
250 // TODO: Remove m_begin and (if possible) m_end when we remove slice().
252 size_type m_begin = 0;
254 size_type m_end = 0;
255
256private:
257 template<typename Tuple, std::size_t... indexes>
258 void extract_fields(Tuple &t, std::index_sequence<indexes...>) const
259 {
260 (extract_value<Tuple, indexes>(t), ...);
261 }
262
263 template<typename Tuple, std::size_t index>
264 void extract_value(Tuple &t) const;
265
267 template<typename TUPLE, std::size_t... indexes>
268 auto get_tuple(std::index_sequence<indexes...>) const
269 {
270 return std::make_tuple(get_field<TUPLE, indexes>()...);
271 }
272
274 template<typename TUPLE, std::size_t index> auto get_field() const
275 {
276 return (*this)[index].as<std::tuple_element_t<index, TUPLE>>();
277 }
278};
279
280
282class PQXX_LIBEXPORT const_row_iterator : public field
283{
284public:
285 using iterator_category = std::random_access_iterator_tag;
286 using value_type = field const;
287 using pointer = field const *;
291
292#include "pqxx/internal/ignore-deprecated-pre.hxx"
293 const_row_iterator() noexcept = default;
294#include "pqxx/internal/ignore-deprecated-post.hxx"
295 const_row_iterator(row const &t, row_size_type c) noexcept :
296 field{t.m_result, t.m_index, c}
297 {}
298 const_row_iterator(field const &F) noexcept : field{F} {}
299 const_row_iterator(const_row_iterator const &) noexcept = default;
301
306 [[nodiscard]] constexpr pointer operator->() const noexcept { return this; }
307 [[nodiscard]] reference operator*() const noexcept { return {*this}; }
309
314 const_row_iterator &operator=(const_row_iterator const &) noexcept = default;
316
317 const_row_iterator operator++(int) noexcept;
318 const_row_iterator &operator++() noexcept
319 {
320 ++m_col;
321 return *this;
322 }
323 const_row_iterator operator--(int) noexcept;
325 {
326 --m_col;
327 return *this;
328 }
329
331 {
332 m_col = size_type(difference_type(m_col) + i);
333 return *this;
334 }
336 {
337 m_col = size_type(difference_type(m_col) - i);
338 return *this;
339 }
341
346 [[nodiscard]] constexpr bool
347 operator==(const_row_iterator const &i) const noexcept
348 {
349 return col() == i.col();
350 }
351 [[nodiscard]] constexpr bool
352 operator!=(const_row_iterator const &i) const noexcept
353 {
354 return col() != i.col();
355 }
356 [[nodiscard]] constexpr bool
357 operator<(const_row_iterator const &i) const noexcept
358 {
359 return col() < i.col();
360 }
361 [[nodiscard]] constexpr bool
362 operator<=(const_row_iterator const &i) const noexcept
363 {
364 return col() <= i.col();
365 }
366 [[nodiscard]] constexpr bool
367 operator>(const_row_iterator const &i) const noexcept
368 {
369 return col() > i.col();
370 }
371 [[nodiscard]] constexpr bool
372 operator>=(const_row_iterator const &i) const noexcept
373 {
374 return col() >= i.col();
375 }
377
382 [[nodiscard]] inline const_row_iterator
383 operator+(difference_type) const noexcept;
384
385 friend const_row_iterator
386 operator+(difference_type, const_row_iterator const &) noexcept;
387
388 [[nodiscard]] inline const_row_iterator
389 operator-(difference_type) const noexcept;
390 [[nodiscard]] inline difference_type
391 operator-(const_row_iterator const &) const noexcept;
393};
394
395
397class PQXX_LIBEXPORT const_reverse_row_iterator : private const_row_iterator
398{
399public:
407
408 const_reverse_row_iterator() noexcept = default;
410 default;
412
413 explicit const_reverse_row_iterator(super const &rhs) noexcept :
415 {
416 super::operator--();
417 }
418
419 [[nodiscard]] PQXX_PURE iterator_type base() const noexcept;
420
425 using iterator_type::operator->;
426 using iterator_type::operator*;
428
433 const_reverse_row_iterator &
434 operator=(const_reverse_row_iterator const &r) noexcept
435 {
436 iterator_type::operator=(r);
437 return *this;
438 }
440 {
441 iterator_type::operator--();
442 return *this;
443 }
444 const_reverse_row_iterator operator++(int) noexcept;
446 {
447 iterator_type::operator++();
448 return *this;
449 }
450 const_reverse_row_iterator operator--(int);
452 {
453 iterator_type::operator-=(i);
454 return *this;
455 }
457 {
458 iterator_type::operator+=(i);
459 return *this;
460 }
462
467 [[nodiscard]] const_reverse_row_iterator
468 operator+(difference_type i) const noexcept
469 {
470 return const_reverse_row_iterator{base() - i};
471 }
472 [[nodiscard]] const_reverse_row_iterator
474 {
475 return const_reverse_row_iterator{base() + i};
476 }
477 [[nodiscard]] difference_type
478 operator-(const_reverse_row_iterator const &rhs) const noexcept
479 {
480 return rhs.const_row_iterator::operator-(*this);
481 }
483
488 [[nodiscard]] bool
489 operator==(const_reverse_row_iterator const &rhs) const noexcept
490 {
491 return iterator_type::operator==(rhs);
492 }
493 [[nodiscard]] bool
494 operator!=(const_reverse_row_iterator const &rhs) const noexcept
495 {
496 return !operator==(rhs);
497 }
498
499 [[nodiscard]] constexpr bool
500 operator<(const_reverse_row_iterator const &rhs) const noexcept
501 {
502 return iterator_type::operator>(rhs);
503 }
504 [[nodiscard]] constexpr bool
505 operator<=(const_reverse_row_iterator const &rhs) const noexcept
506 {
507 return iterator_type::operator>=(rhs);
508 }
509 [[nodiscard]] constexpr bool
510 operator>(const_reverse_row_iterator const &rhs) const noexcept
511 {
512 return iterator_type::operator<(rhs);
513 }
514 [[nodiscard]] constexpr bool
515 operator>=(const_reverse_row_iterator const &rhs) const noexcept
516 {
517 return iterator_type::operator<=(rhs);
518 }
520};
521
522
523const_row_iterator
525{
526 // TODO:: More direct route to home().columns()?
527 return {
528 row{home(), idx(), home().columns()},
529 size_type(difference_type(col()) + o)};
530}
531
534{
535 return i + o;
536}
537
540{
541 // TODO:: More direct route to home().columns()?
542 return {
543 row{home(), idx(), home().columns()},
544 size_type(difference_type(col()) - o)};
545}
546
549{
550 return difference_type(num() - i.num());
551}
552
553
554template<typename Tuple, std::size_t index>
555inline void row::extract_value(Tuple &t) const
556{
557 using field_type = strip_t<decltype(std::get<index>(t))>;
558 field const f{m_result, m_index, index};
559 std::get<index>(t) = from_string<field_type>(f);
560}
561} // namespace pqxx
562#endif
The home of all libpqxx classes, functions, templates, etc.
Definition array.hxx:33
int row_size_type
Number of fields in a row of database data.
Definition types.hxx:34
std::remove_cv_t< std::remove_reference_t< TYPE > > strip_t
Remove any constness, volatile, and reference-ness from a type.
Definition types.hxx:91
int row_difference_type
Difference between row sizes.
Definition types.hxx:37
const_row_iterator operator+(const_row_iterator::difference_type o, const_row_iterator const &i) noexcept
Definition row.hxx:532
int result_size_type
Number of rows in a result set.
Definition types.hxx:28
Internal items for libpqxx' own use. Do not use these yourself.
Definition composite.hxx:84
Error in usage of libpqxx library, similar to std::logic_error.
Definition except.hxx:249
Reference to a field in a result set.
Definition field.hxx:35
Result set containing data returned by a query or command.
Definition result.hxx:73
result_size_type size_type
Definition result.hxx:75
Definition row.hxx:28
Reference to one row in a result.
Definition row.hxx:47
std::tuple< TYPE... > as() const
Extract entire row's values into a tuple.
Definition row.hxx:200
row_size_type size_type
Definition row.hxx:49
oid column_type(zview col_name) const
Return a column's type.
Definition row.hxx:128
row_difference_type difference_type
Definition row.hxx:50
result m_result
Result set of which this is one row.
Definition row.hxx:241
result::size_type m_index
Row number.
Definition row.hxx:248
constexpr result::size_type num() const noexcept
Definition row.hxx:159
row() noexcept=default
constexpr result::size_type rownumber() const noexcept
Row number, assuming this is a real row and not end()/rend().
Definition row.hxx:112
TUPLE as_tuple() const
Convert to a given tuple of values, don't check sizes.
Definition row.hxx:225
void check_size(size_type expected) const
Throw usage_error if row size is not expected.
Definition row.hxx:213
size_type table_column(zview col_name) const
What column number in its table did this result column come from?
Definition row.hxx:153
void convert(Tuple &t) const
Convert entire row to tuple fields, without checking row size.
Definition row.hxx:233
oid column_table(zview col_name) const
What table did this column come from?
Definition row.hxx:137
Iterator for fields in a row. Use as row::const_iterator.
Definition row.hxx:283
const_row_iterator operator-(difference_type) const noexcept
Definition row.hxx:539
const_row_iterator & operator=(const_row_iterator &&) noexcept=default
reference operator*() const noexcept
Definition row.hxx:307
const_row_iterator(field const &F) noexcept
Definition row.hxx:298
friend const_row_iterator operator+(difference_type, const_row_iterator const &) noexcept
Definition row.hxx:532
constexpr bool operator>=(const_row_iterator const &i) const noexcept
Definition row.hxx:372
const_row_iterator(const_row_iterator const &) noexcept=default
const_row_iterator & operator=(const_row_iterator const &) noexcept=default
std::random_access_iterator_tag iterator_category
Definition row.hxx:285
constexpr bool operator==(const_row_iterator const &i) const noexcept
Definition row.hxx:347
field const * pointer
Definition row.hxx:287
field const value_type
Definition row.hxx:286
constexpr bool operator!=(const_row_iterator const &i) const noexcept
Definition row.hxx:352
const_row_iterator(const_row_iterator &&) noexcept=default
row_size_type size_type
Definition row.hxx:288
const_row_iterator & operator--() noexcept
Definition row.hxx:324
const_row_iterator() noexcept=default
row_difference_type difference_type
Definition row.hxx:289
const_row_iterator & operator-=(difference_type i) noexcept
Definition row.hxx:335
const_row_iterator & operator+=(difference_type i) noexcept
Definition row.hxx:330
const_row_iterator(row const &t, row_size_type c) noexcept
Definition row.hxx:295
constexpr bool operator>(const_row_iterator const &i) const noexcept
Definition row.hxx:367
Reverse iterator for a row. Use as row::const_reverse_iterator.
Definition row.hxx:398
const_reverse_row_iterator operator++() noexcept
Definition row.hxx:439
bool operator!=(const_reverse_row_iterator const &rhs) const noexcept
Definition row.hxx:494
constexpr bool operator>=(const_reverse_row_iterator const &rhs) const noexcept
Definition row.hxx:515
constexpr bool operator>(const_reverse_row_iterator const &rhs) const noexcept
Definition row.hxx:510
difference_type operator-(const_reverse_row_iterator const &rhs) const noexcept
Definition row.hxx:478
const_reverse_row_iterator & operator+=(difference_type i) noexcept
Definition row.hxx:451
const_reverse_row_iterator operator+(difference_type i) const noexcept
Definition row.hxx:468
const_reverse_row_iterator & operator-=(difference_type i) noexcept
Definition row.hxx:456
const_reverse_row_iterator & operator--() noexcept
Definition row.hxx:445
row_difference_type difference_type
Definition row.hxx:289
bool operator==(const_reverse_row_iterator const &rhs) const noexcept
Definition row.hxx:489
const_reverse_row_iterator() noexcept=default
const_reverse_row_iterator operator-(difference_type i) noexcept
Definition row.hxx:473
iterator_type::value_type value_type
Definition row.hxx:405
Marker-type wrapper: zero-terminated std::string_view.
Definition zview.hxx:38