libpqxx  7.3.1
pqxx::const_result_iterator Class Reference

Iterator for rows in a result. Use as result::const_iterator. More...

#include <result_iterator.hxx>

Inheritance diagram for pqxx::const_result_iterator:

Public Types

using iterator_category = std::random_access_iterator_tag
 
using value_type = row const
 
using pointer = row const *
 
using reference = row
 
using size_type = result_size_type
 
using difference_type = result_difference_type
 
- Public Types inherited from pqxx::row
using size_type = row_size_type
 
using difference_type = row_difference_type
 
using const_iterator = const_row_iterator
 
using iterator = const_iterator
 
using reference = field
 
using pointer = const_row_iterator
 
using const_reverse_iterator = const_reverse_row_iterator
 
using reverse_iterator = const_reverse_iterator
 

Public Member Functions

 const_result_iterator () noexcept=default
 Create an iterator, but in an unusable state. More...
 
 const_result_iterator (const_result_iterator const &) noexcept=default
 Copy an iterator. More...
 
 const_result_iterator (const_result_iterator &&) noexcept=default
 Move an iterator. More...
 
 const_result_iterator (row const &t) noexcept
 Begin iterating a row. More...
 
Dereferencing operators

An iterator "points to" its own row, which is also itself. This makes it easy to address a result as a two-dimensional container, without going through the intermediate step of dereferencing the iterator. It makes the interface similar to C pointer/array semantics.

IIRC Alex Stepanov, the inventor of the STL, once remarked that having this as standard behaviour for pointers would be useful in some algorithms. So even if this makes me look foolish, I would seem to be in distinguished company.

pointer operator-> () const
 Dereference the iterator. More...
 
reference operator* () const
 Dereference the iterator. More...
 
Manipulations
const_result_iteratoroperator= (const_result_iterator const &rhs)
 
const_result_iteratoroperator= (const_result_iterator &&rhs)
 
const_result_iterator operator++ (int)
 
const_result_iteratoroperator++ ()
 
const_result_iterator operator-- (int)
 
const_result_iteratoroperator-- ()
 
const_result_iteratoroperator+= (difference_type i)
 
const_result_iteratoroperator-= (difference_type i)
 
void swap (const_result_iterator &other) noexcept
 Interchange two iterators in an exception-safe manner. More...
 
Comparisons
bool operator== (const_result_iterator const &i) const
 
bool operator!= (const_result_iterator const &i) const
 
bool operator< (const_result_iterator const &i) const
 
bool operator<= (const_result_iterator const &i) const
 
bool operator> (const_result_iterator const &i) const
 
bool operator>= (const_result_iterator const &i) const
 
- Public Member Functions inherited from pqxx::row
 row ()=default
 
 row (row &&)=default
 
 row (row const &)=default
 
rowoperator= (row const &)=default
 
rowoperator= (row &&)=default
 
const_iterator begin () const noexcept
 
const_iterator cbegin () const noexcept
 
const_iterator end () const noexcept
 
const_iterator cend () const noexcept
 
result::size_type num () const
 
row slice (size_type sbegin, size_type send) const
 
PQXX_PURE bool empty () const noexcept
 
template<typename Tuple >
void to (Tuple &t) const
 Extract entire row's values into a tuple. More...
 
template<typename... TYPE>
std::tuple< TYPE... > as () const
 
PQXX_PURE bool operator== (row const &) const noexcept
 
bool operator!= (row const &rhs) const noexcept
 
reference front () const noexcept
 
reference back () const noexcept
 
const_reverse_row_iterator rbegin () const
 
const_reverse_row_iterator crbegin () const
 
const_reverse_row_iterator rend () const
 
const_reverse_row_iterator crend () const
 
reference operator[] (size_type) const noexcept
 
reference operator[] (zview col_name) const
 
reference at (size_type) const
 
reference at (zview col_name) const
 
size_type size () const noexcept
 
void swap (row &) noexcept
 
result::size_type rownumber () const noexcept
 Row number, assuming this is a real row and not end()/rend(). More...
 
size_type column_number (zview col_name) const
 Number of given column (throws exception if it doesn't exist). More...
 
oid column_type (size_type) const
 Return a column's type. More...
 
oid column_type (zview col_name) const
 Return a column's type. More...
 
oid column_table (size_type col_num) const
 What table did this column come from? More...
 
oid column_table (zview col_name) const
 What table did this column come from? More...
 
size_type table_column (size_type) const
 What column number in its table did this result column come from? More...
 
size_type table_column (zview col_name) const
 What column number in its table did this result column come from? More...
 

Friends

class pqxx::result
 

Arithmetic operators

const_result_iterator operator+ (difference_type, const_result_iterator const &)
 
const_result_iterator operator+ (difference_type) const
 
const_result_iterator operator- (difference_type) const
 
difference_type operator- (const_result_iterator const &) const
 

Additional Inherited Members

- Protected Member Functions inherited from pqxx::row
 row (result const &r, result_size_type i) noexcept
 
void check_size (size_type expected) const
 Throw usage_error if row size is not expected. More...
 
template<typename Tuple >
void convert (Tuple &t) const
 Convert entire row to tuple fields, without checking row size. More...
 
- Protected Attributes inherited from pqxx::row
result m_result
 Result set of which this is one row. More...
 
result::size_type m_index = 0
 Row number. More...
 
size_type m_begin = 0
 First column in slice. This row ignores lower-numbered columns. More...
 
size_type m_end = 0
 End column in slice. This row only sees lower-numbered columns. More...
 

Detailed Description

Iterator for rows in a result. Use as result::const_iterator.

A result, once obtained, cannot be modified. Therefore there is no plain iterator type for result. However its const_iterator type can be used to inspect its rows without changing them.

Member Typedef Documentation

◆ difference_type

◆ iterator_category

using pqxx::const_result_iterator::iterator_category = std::random_access_iterator_tag

◆ pointer

◆ reference

◆ size_type

◆ value_type

Constructor & Destructor Documentation

◆ const_result_iterator() [1/4]

pqxx::const_result_iterator::const_result_iterator ( )
defaultnoexcept

Create an iterator, but in an unusable state.

◆ const_result_iterator() [2/4]

pqxx::const_result_iterator::const_result_iterator ( const_result_iterator const &  )
defaultnoexcept

Copy an iterator.

◆ const_result_iterator() [3/4]

pqxx::const_result_iterator::const_result_iterator ( const_result_iterator &&  )
defaultnoexcept

Move an iterator.

◆ const_result_iterator() [4/4]

pqxx::const_result_iterator::const_result_iterator ( row const &  t)
noexcept

Begin iterating a row.

Member Function Documentation

◆ operator!=()

bool pqxx::const_result_iterator::operator!= ( const_result_iterator const &  i) const

References pqxx::row::m_index.

◆ operator*()

reference pqxx::const_result_iterator::operator* ( ) const

Dereference the iterator.

References pqxx::row::at(), pqxx::row::back(), pqxx::row::front(), and pqxx::row::rownumber().

◆ operator+()

const_result_iterator pqxx::const_result_iterator::operator+ ( result::difference_type  o) const

◆ operator++() [1/2]

pqxx::const_result_iterator pqxx::const_result_iterator::operator++ ( int  )

◆ operator++() [2/2]

const_result_iterator& pqxx::const_result_iterator::operator++ ( )

◆ operator+=()

const_result_iterator& pqxx::const_result_iterator::operator+= ( difference_type  i)

◆ operator-() [1/2]

const_result_iterator pqxx::const_result_iterator::operator- ( result::difference_type  o) const

◆ operator-() [2/2]

result::difference_type pqxx::const_result_iterator::operator- ( const_result_iterator const &  i) const

References pqxx::row::num().

◆ operator--() [1/2]

pqxx::const_result_iterator pqxx::const_result_iterator::operator-- ( int  )

◆ operator--() [2/2]

const_result_iterator& pqxx::const_result_iterator::operator-- ( )

◆ operator-=()

const_result_iterator& pqxx::const_result_iterator::operator-= ( difference_type  i)

◆ operator->()

pointer pqxx::const_result_iterator::operator-> ( ) const

Dereference the iterator.

◆ operator<()

bool pqxx::const_result_iterator::operator< ( const_result_iterator const &  i) const

References pqxx::row::m_index.

◆ operator<=()

bool pqxx::const_result_iterator::operator<= ( const_result_iterator const &  i) const

References pqxx::row::m_index.

◆ operator=() [1/2]

const_result_iterator& pqxx::const_result_iterator::operator= ( const_result_iterator const &  rhs)

◆ operator=() [2/2]

const_result_iterator& pqxx::const_result_iterator::operator= ( const_result_iterator &&  rhs)

◆ operator==()

bool pqxx::const_result_iterator::operator== ( const_result_iterator const &  i) const

References pqxx::row::m_index.

◆ operator>()

bool pqxx::const_result_iterator::operator> ( const_result_iterator const &  i) const

References pqxx::row::m_index.

◆ operator>=()

bool pqxx::const_result_iterator::operator>= ( const_result_iterator const &  i) const

◆ swap()

void pqxx::const_result_iterator::swap ( const_result_iterator other)
noexcept

Interchange two iterators in an exception-safe manner.

References pqxx::row::swap().

Referenced by pqxx::const_reverse_result_iterator::swap().

Friends And Related Function Documentation

◆ operator+

const_result_iterator operator+ ( result::difference_type  o,
const_result_iterator const &  i 
)
friend

◆ pqxx::result

friend class pqxx::result
friend

The documentation for this class was generated from the following files: