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 
26 namespace pqxx::internal
27 {
28 template<typename... T> class result_iter;
29 } // namespace pqxx::internal
30 
31 
32 namespace pqxx
33 {
35 
46 class PQXX_LIBEXPORT row
47 {
48 public:
53  using reference = field;
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 
121  [[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 
207 protected:
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 
256 private:
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 
282 class PQXX_LIBEXPORT const_row_iterator : public field
283 {
284 public:
285  using iterator_category = std::random_access_iterator_tag;
286  using value_type = field const;
287  using pointer = field const *;
290  using reference = field;
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;
300  const_row_iterator(const_row_iterator &&) 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;
315  const_row_iterator &operator=(const_row_iterator &&) 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;
324  const_row_iterator &operator--() 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 
397 class PQXX_LIBEXPORT const_reverse_row_iterator : private const_row_iterator
398 {
399 public:
400  using super = const_row_iterator;
401  using iterator_type = const_row_iterator;
407 
408  const_reverse_row_iterator() noexcept = default;
410  default;
412 
413  explicit const_reverse_row_iterator(super const &rhs) noexcept :
414  const_row_iterator{rhs}
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;
445  const_reverse_row_iterator &operator--() noexcept
446  {
447  iterator_type::operator++();
448  return *this;
449  }
450  const_reverse_row_iterator operator--(int);
451  const_reverse_row_iterator &operator+=(difference_type i) noexcept
452  {
453  iterator_type::operator-=(i);
454  return *this;
455  }
456  const_reverse_row_iterator &operator-=(difference_type i) noexcept
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
473  operator-(difference_type i) noexcept
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 
523 const_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 
538 inline const_row_iterator
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 
554 template<typename Tuple, std::size_t index>
555 inline 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
Error in usage of libpqxx library, similar to std::logic_error.
Definition: except.hxx:248
TUPLE as_tuple() const
Convert to a given tuple of values, don't check sizes.
Definition: row.hxx:225
Result set containing data returned by a query or command.
Definition: result.hxx:72
constexpr bool operator>(const_row_iterator const &i) const noexcept
Definition: row.hxx:367
constexpr result::size_type num() const noexcept
Definition: row.hxx:159
constexpr bool operator!=(const_row_iterator const &i) const noexcept
Definition: row.hxx:352
constexpr bool operator>=(const_row_iterator const &i) const noexcept
Definition: row.hxx:372
const_row_iterator & operator+=(difference_type i) noexcept
Definition: row.hxx:330
result_size_type size_type
Definition: result.hxx:75
const_reverse_row_iterator operator+(difference_type i) const noexcept
Definition: row.hxx:468
constexpr bool operator>(const_reverse_row_iterator const &rhs) const noexcept
Definition: row.hxx:510
constexpr bool operator==(const_row_iterator const &i) const noexcept
Definition: row.hxx:347
Internal items for libpqxx' own use. Do not use these yourself.
Definition: composite.hxx:83
Reference to a field in a result set.
Definition: field.hxx:34
Reference to one row in a result.
Definition: row.hxx:46
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:473
std::tuple< TYPE... > as() const
Extract entire row's values into a tuple.
Definition: row.hxx:200
field_size_type size_type
Definition: field.hxx:37
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:32
const_reverse_row_iterator & operator-=(difference_type i) noexcept
Definition: row.hxx:456
row_difference_type difference_type
Definition: row.hxx:50
int row_size_type
Number of fields in a row of database data.
Definition: types.hxx:34
int result_size_type
Number of rows in a result set.
Definition: types.hxx:28
row_difference_type difference_type
Definition: row.hxx:289
void check_size(size_type expected) const
Throw usage_error if row size is not expected.
Definition: row.hxx:213
Marker-type wrapper: zero-terminated std::string_view.
Definition: zview.hxx:37
row_size_type size_type
Definition: row.hxx:49
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
const_row_iterator operator+(const_row_iterator::difference_type o, const_row_iterator const &i) noexcept
Definition: row.hxx:532
reference operator*() const noexcept
Definition: row.hxx:307
constexpr bool operator>=(const_reverse_row_iterator const &rhs) const noexcept
Definition: row.hxx:515
const_row_iterator & operator-=(difference_type i) noexcept
Definition: row.hxx:335
const_row_iterator operator-(difference_type) const noexcept
Definition: row.hxx:539
Iterator for fields in a row. Use as row::const_iterator.
Definition: row.hxx:282
field const * pointer
Definition: row.hxx:287
bool operator!=(const_reverse_row_iterator const &rhs) const noexcept
Definition: row.hxx:494
oid column_type(zview col_name) const
Return a column's type.
Definition: row.hxx:128
const_reverse_row_iterator & operator+=(difference_type i) noexcept
Definition: row.hxx:451
bool operator==(const_reverse_row_iterator const &rhs) const noexcept
Definition: row.hxx:489
std::random_access_iterator_tag iterator_category
Definition: row.hxx:285
void convert(Tuple &t) const
Convert entire row to tuple fields, without checking row size.
Definition: row.hxx:233
const_row_iterator(row const &t, row_size_type c) noexcept
End a code block started by "ignore-deprecated-pre.hxx".
Definition: row.hxx:295
result m_result
Result set of which this is one row.
Definition: row.hxx:241
field const value_type
Definition: row.hxx:286
size_type table_column(zview col_name) const
What column number in its table did this result column come from?
Definition: row.hxx:153
Definition: row.hxx:28
const_reverse_row_iterator operator++() noexcept
Definition: row.hxx:439
oid column_table(zview col_name) const
What table did this column come from?
Definition: row.hxx:137
Reverse iterator for a row. Use as row::const_reverse_iterator.
Definition: row.hxx:397
const_row_iterator(field const &F) noexcept
Definition: row.hxx:298
int row_difference_type
Difference between row sizes.
Definition: types.hxx:37
const_row_iterator operator+(difference_type) const noexcept
Definition: row.hxx:524