/usr/include/pqxx/result.hxx is in libpqxx3-dev 1:3.1.1-0ubuntu4.
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/*-------------------------------------------------------------------------
*
* FILE
* pqxx/result.hxx
*
* DESCRIPTION
* definitions for the pqxx::result class and support classes.
* pqxx::result represents the set of result tuples from a database query
* DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/result instead.
*
* Copyright (c) 2001-2013, Jeroen T. Vermeulen <jtv@xs4all.nl>
*
* See COPYING for copyright license. If you did not receive a file called
* COPYING with this source code, please notify the distributor of this mistake,
* or contact the author.
*
*-------------------------------------------------------------------------
*/
#ifndef PQXX_H_RESULT
#define PQXX_H_RESULT
#include "pqxx/compiler-public.hxx"
#include "pqxx/compiler-internal-pre.hxx"
#ifdef PQXX_HAVE_IOS
#include <ios>
#endif
#include <stdexcept>
#include "pqxx/except"
#include "pqxx/strconv"
#include "pqxx/util"
/* Methods tested in eg. self-test program test001 are marked with "//[t1]"
*/
// TODO: Support SQL arrays
namespace pqxx
{
class result;
namespace internal
{
class sql_cursor;
/// Information shared between all copies of a result set
struct PQXX_PRIVATE result_data
{
/// Underlying libpq-managed result set
/** @warning This member is duplicated in the result object as a performance
* shortcut.
*/
pqxx::internal::pq::PGresult *data;
/// Frontend/backend protocol version
int protocol;
/// Query string that yielded this result
PGSTD::string query;
int encoding_code;
// TODO: Locking for result copy-construction etc. also goes here
result_data();
result_data(pqxx::internal::pq::PGresult *,
int protocol,
const PGSTD::string &,
int encoding_code);
~result_data();
};
void PQXX_LIBEXPORT freemem_result_data(const result_data *) throw ();
} // namespace internal
namespace internal
{
namespace gate
{
class result_connection;
class result_creation;
class result_sql_cursor;
} // namespace internal::gate
} // namespace internal
/// Query or command result set.
/** This behaves as a container (as defined by the C++ standard library) and
* provides random access const iterators to iterate over its tuples. A tuple
* can also be accessed by indexing a result R by the tuple's zero-based
* number:
*
* @code
* for (result::size_type i=0; i < R.size(); ++i) Process(R[i]);
* @endcode
*
* Result sets in libpqxx are lightweight, reference-counted wrapper objects
* (following the Proxy design pattern) that are small and cheap to copy. Think
* of a result object as a "smart pointer" to an underlying result set.
*
* @warning The result set that a result object points to is not thread-safe.
* If you copy a result object, it still refers to the same underlying result
* set. So never copy, destroy, query, or otherwise access a result while
* another thread may be copying, destroying, querying, or otherwise accessing
* the same result set--even if it is doing so through a different result
* object!
*/
class PQXX_LIBEXPORT result :
private internal::PQAlloc<
const internal::result_data, internal::freemem_result_data>
{
typedef internal::PQAlloc<
const internal::result_data, internal::freemem_result_data> super;
public:
class const_iterator;
class const_fielditerator;
class const_reverse_fielditerator;
class tuple;
class field;
typedef unsigned long size_type;
typedef signed long difference_type;
typedef tuple reference;
typedef const_iterator pointer;
/// Reference to one row in a result.
/** A tuple represents one row (also called a tuple) in a query result set.
* It also acts as a container mapping column numbers or names to field
* values (see below):
*
* @code
* cout << tuple["date"].c_str() << ": " << tuple["name"].c_str() << endl;
* @endcode
*
* The tuple itself acts like a (non-modifyable) container, complete with its
* own const_iterator and const_reverse_iterator.
*/
class PQXX_LIBEXPORT tuple
{
public:
typedef unsigned int size_type;
typedef signed int difference_type;
typedef const_fielditerator const_iterator;
typedef const_iterator iterator;
typedef field reference;
typedef const_fielditerator pointer;
typedef const_reverse_fielditerator const_reverse_iterator;
typedef const_reverse_iterator reverse_iterator;
/// @deprecated Do not use this constructor. It will become private.
tuple(const result *r, result::size_type i) throw () :
m_Home(r), m_Index(i), m_Begin(0), m_End(r ? r->columns() : 0) {}
~tuple() throw () {} // Yes Scott Meyers, you're absolutely right[1]
/**
* @name Comparison
*/
//@{
bool operator==(const tuple &) const throw (); //[t75]
bool operator!=(const tuple &rhs) const throw () //[t75]
{ return !operator==(rhs); }
//@}
const_iterator begin() const throw () //[t82]
{ return const_iterator(*this, m_Begin); }
const_iterator end() const throw () //[t82]
{ return const_iterator(*this, m_End); }
/**
* @name Field access
*/
//@{
reference front() const throw () { return field(*this, m_Begin); } //[t74]
reference back() const throw () { return field(*this, m_End-1); } //[t75]
const_reverse_fielditerator rbegin() const; //[t82]
const_reverse_fielditerator rend() const; //[t82]
reference operator[](size_type i) const throw () //[t11]
{ return field(*this, m_Begin+i); }
reference operator[](int i) const throw () //[t2]
{ return operator[](size_type(i)); }
reference operator[](const char f[]) const //[t11]
{ return at(f); }
reference operator[](const PGSTD::string &s) const //[t11]
{ return operator[](s.c_str()); }
reference at(size_type) const throw (range_error); //[t11]
reference at(int i) const throw (range_error) //[t11]
{ return at(size_type(i)); }
reference at(const char[]) const; //[t11]
reference at(const PGSTD::string &s) const //[t11]
{ return at(s.c_str()); }
//@}
size_type size() const throw () { return m_End-m_Begin; } //[t11]
void swap(tuple &) throw (); //[t11]
result::size_type rownumber() const throw () { return m_Index; } //[t11]
/**
* @name Column information
*/
//@{
/// Number of given column (throws exception if it doesn't exist)
size_type column_number(const PGSTD::string &ColName) const //[t30]
{ return column_number(ColName.c_str()); }
/// Number of given column (throws exception if it doesn't exist)
size_type column_number(const char[]) const; //[t30]
/// Type of given column
oid column_type(size_type ColNum) const //[t7]
{ return m_Home->column_type(m_Begin+ColNum); }
/// Type of given column
oid column_type(int ColNum) const //[t7]
{ return column_type(size_type(ColNum)); }
/// Type of given column
oid column_type(const PGSTD::string &ColName) const //[t7]
{ return column_type(column_number(ColName)); }
/// Type of given column
oid column_type(const char ColName[]) const //[t7]
{ return column_type(column_number(ColName)); }
/// What table did this column come from? Requires PostgreSQL 7.4 C API.
/** Only defined if the libpqxx library was compiled against a libpq
* version that supports the @c PQftable function.
*
* If you get a link error saying this function is undefined, that must be
* because libpqxx was compiled against an older version of libpq. The
* @c PQftable function first became available in PostgreSQL 7.4.
*/
oid column_table(size_type ColNum) const //[t2]
{ return m_Home->column_table(m_Begin+ColNum); }
/// What table did this column come from? Requires PostgreSQL 7.4 C API.
/** Only defined if the libpqxx library was compiled against a libpq
* version that supports the @c PQftable function.
*
* If you get a link error saying this function is undefined, that must be
* because libpqxx was compiled against an older version of libpq. The
* @c PQftable function first became available in PostgreSQL 7.4.
*/
oid column_table(int ColNum) const //[t2]
{ return column_table(size_type(ColNum)); }
/// What table did this column come from? Requires PostgreSQL 7.4 C API.
/** Only defined if the libpqxx library was compiled against a libpq
* version that supports the @c PQftable function.
*
* If you get a link error saying this function is undefined, that must be
* because libpqxx was compiled against an older version of libpq. The
* @c PQftable function first became available in PostgreSQL 7.4.
*/
oid column_table(const PGSTD::string &ColName) const //[t2]
{ return column_table(column_number(ColName)); }
/// What column number in its table did this result column come from?
/** A meaningful answer can be given only if the column in question comes
* directly from a column in a table. If the column is computed in any
* other way, a logic_error will be thrown.
*
* @param ColNum a zero-based column number in this result set
* @return a zero-based column number in originating table
*
* Requires libpq from PostgreSQL 7.4 or better, as well as a server version
* of at least 7.4.
*/
size_type table_column(size_type ColNum) const //[t93]
{ return m_Home->table_column(m_Begin+ColNum); }
/// What column number in its table did this result column come from?
size_type table_column(int ColNum) const //[t93]
{ return table_column(size_type(ColNum)); }
/// What column number in its table did this result column come from?
size_type table_column(const PGSTD::string &ColName) const //[t93]
{ return table_column(column_number(ColName)); }
//@}
result::size_type num() const { return rownumber(); } //[t1]
/** Produce a slice of this tuple, containing the given range of columns.
*
* The slice runs from the range's starting column to the range's end
* column, exclusive. It looks just like a normal result tuple, except
* slices can be empty.
*
* @warning Slicing is a relatively new feature, and not all software may be
* prepared to deal with empty slices. If there is any chance that your
* program might be creating empty slices and passing them to code that may
* not be designed with the possibility of empty tuples in mind, be sure to
* test for that case.
*/
tuple slice(size_type Begin, size_type End) const;
// Is this an empty slice?
bool empty() const throw ();
protected:
friend class field;
const result *m_Home;
result::size_type m_Index;
size_type m_Begin;
size_type m_End;
private:
// Not allowed:
tuple();
};
/// Reference to a field in a result set.
/** A field represents one entry in a tuple. It represents an actual value
* in the result set, and can be converted to various types.
*/
class PQXX_LIBEXPORT field
{
public:
typedef size_t size_type;
/// Constructor.
/** Create field as reference to a field in a result set.
* @param T Tuple that this field is part of.
* @param C Column number of this field.
*/
field(const tuple &T, tuple::size_type C) throw () : //[t1]
m_tup(T), m_col(C) {}
/**
* @name Comparison
*/
//@{
/// Byte-by-byte comparison of two fields (all nulls are considered equal)
/** @warning null handling is still open to discussion and change!
*
* Handling of null values differs from that in SQL where a comparison
* involving a null value yields null, so nulls are never considered equal
* to one another or even to themselves.
*
* Null handling also probably differs from the closest equivalent in C++,
* which is the NaN (Not-a-Number) value, a singularity comparable to
* SQL's null. This is because the builtin == operator demands that a == a.
*
* The usefulness of this operator is questionable. No interpretation
* whatsoever is imposed on the data; 0 and 0.0 are considered different,
* as are null vs. the empty string, or even different (but possibly
* equivalent and equally valid) encodings of the same Unicode character
* etc.
*/
bool operator==(const field &) const; //[t75]
/// Byte-by-byte comparison (all nulls are considered equal)
/** @warning See operator==() for important information about this operator
*/
bool operator!=(const field &rhs) const {return !operator==(rhs);} //[t82]
//@}
/**
* @name Column information
*/
//@{
/// Column name
const char *name() const { return home()->column_name(col()); } //[t11]
/// Column type
oid type() const { return home()->column_type(col()); } //[t7]
/// What table did this column come from? Requires PostgreSQL 7.4 C API.
/** Only defined if the libpqxx library was compiled against a libpq
* version that supports the @c PQftable function.
*
* If you get a link error saying this function is undefined, that must be
* because libpqxx was compiled against an older version of libpq. The
* @c PQftable function first became available in PostgreSQL 7.4.
*/
oid table() const { return home()->column_table(col()); } //[t2]
tuple::size_type num() const { return col(); } //[t82]
/// What column number in its originating table did this column come from?
tuple::size_type table_column() const //[t93]
{ return home()->table_column(col()); }
//@}
/**
* @name Content access
*/
//@{
/// Read as plain C string
/** Since the field's data is stored internally in the form of a
* zero-terminated C string, this is the fastest way to read it. Use the
* to() or as() functions to convert the string to other types such as
* @c int, or to C++ strings.
*/
const char *c_str() const { return home()->GetValue(idx(),col()); } //[t2]
/// Read value into Obj; or leave Obj untouched and return @c false if null
template<typename T> bool to(T &Obj) const //[t3]
{
const char *const bytes = c_str();
if (!bytes[0] && is_null()) return false;
from_string(bytes, Obj);
return true;
}
/// Read value into Obj; or leave Obj untouched and return @c false if null
template<typename T> bool operator>>(T &Obj) const //[t7]
{ return to(Obj); }
#ifdef PQXX_NO_PARTIAL_CLASS_TEMPLATE_SPECIALISATION
/// Specialization: to(string &)
template<> bool to<PGSTD::string>(PGSTD::string &Obj) const;
/// Specialization: <tt>to(const char *&)</tt>.
/** The buffer has the same lifetime as the result, so take care not to
* use it after the result is destroyed.
*/
template<> bool to<const char *>(const char *&Obj) const;
#endif
/// Read value into Obj; or use Default & return @c false if null
template<typename T> bool to(T &Obj, const T &Default) const //[t12]
{
const bool NotNull = to(Obj);
if (!NotNull) Obj = Default;
return NotNull;
}
/// Return value as object of given type, or Default if null
/** Note that unless the function is instantiated with an explicit template
* argument, the Default value's type also determines the result type.
*/
template<typename T> T as(const T &Default) const //[t1]
{
T Obj;
to(Obj, Default);
return Obj;
}
/// Return value as object of given type, or throw exception if null
template<typename T> T as() const //[t45]
{
T Obj;
const bool NotNull = to(Obj);
if (!NotNull) Obj = string_traits<T>::null();
return Obj;
}
bool is_null() const { return home()->GetIsNull(idx(), col()); } //[t12]
size_type size() const throw () //[t11]
{ return home()->GetLength(idx(),col()); }
//@}
private:
const result *home() const throw () { return m_tup.m_Home; }
result::size_type idx() const throw () { return m_tup.m_Index; }
protected:
tuple::size_type col() const throw () { return m_col; }
tuple m_tup;
tuple::size_type m_col;
};
typedef PGSTD::iterator<PGSTD::random_access_iterator_tag,
const tuple,
result::difference_type,
const_iterator,
tuple>
const_iterator_base;
/// Iterator for rows (tuples) in a query result set.
/** 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 tuples without changing them.
*/
class PQXX_LIBEXPORT const_iterator :
public const_iterator_base,
public tuple
{
public:
typedef const tuple *pointer;
typedef tuple reference;
typedef result::size_type size_type;
typedef result::difference_type difference_type;
const_iterator() throw () : tuple(0,0) {}
const_iterator(const tuple &t) throw () : tuple(t) {}
/**
* @name Dereferencing operators
*/
//@{
/** The iterator "points to" its own tuple, which is also itself. This
* allows a result to be addressed as a two-dimensional container without
* going through the intermediate step of dereferencing the iterator. I
* hope this works out to be similar to C pointer/array semantics in useful
* cases.
*
* 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 { return this; } //[t12]
reference operator*() const { return tuple(*this); } //[t12]
//@}
/**
* @name Manipulations
*/
//@{
const_iterator operator++(int); //[t12]
const_iterator &operator++() { ++m_Index; return *this; } //[t1]
const_iterator operator--(int); //[t12]
const_iterator &operator--() { --m_Index; return *this; } //[t12]
const_iterator &operator+=(difference_type i) //[t12]
{ m_Index = size_type(difference_type(m_Index) + i); return *this; }
const_iterator &operator-=(difference_type i) //[t12]
{ m_Index = size_type(difference_type(m_Index) - i); return *this; }
//@}
/**
* @name Comparisons
*/
//@{
bool operator==(const const_iterator &i) const //[t12]
{return m_Index==i.m_Index;}
bool operator!=(const const_iterator &i) const //[t12]
{return m_Index!=i.m_Index;}
bool operator<(const const_iterator &i) const //[t12]
{return m_Index<i.m_Index;}
bool operator<=(const const_iterator &i) const //[t12]
{return m_Index<=i.m_Index;}
bool operator>(const const_iterator &i) const //[t12]
{return m_Index>i.m_Index;}
bool operator>=(const const_iterator &i) const //[t12]
{return m_Index>=i.m_Index;}
//@}
/**
* @name Arithmetic operators
*/
//@{
inline const_iterator operator+(difference_type) const; //[t12]
friend const_iterator
operator+(difference_type, const_iterator); //[t12]
inline const_iterator operator-(difference_type) const; //[t12]
inline difference_type operator-(const_iterator) const; //[t12]
//@}
private:
friend class pqxx::result;
const_iterator(const pqxx::result *r, result::size_type i) throw () :
tuple(r, i) {}
};
typedef const_iterator iterator;
class PQXX_LIBEXPORT const_reverse_iterator : private const_iterator
{
public:
typedef pqxx::result::const_iterator super;
typedef pqxx::result::const_iterator iterator_type;
using iterator_type::iterator_category;
using iterator_type::difference_type;
using iterator_type::pointer;
#ifndef _MSC_VER
using iterator_type::value_type;
using iterator_type::reference;
#else
// Workaround for Visual C++.NET 2003, which has access problems
typedef const tuple &reference;
typedef tuple value_type;
#endif
const_reverse_iterator(const const_reverse_iterator &rhs) : //[t75]
const_iterator(rhs) {}
explicit const_reverse_iterator(const const_iterator &rhs) : //[t75]
const_iterator(rhs) { super::operator--(); }
iterator_type base() const throw (); //[t75]
/**
* @name Dereferencing operators
*/
//@{
using const_iterator::operator->; //[t75]
using const_iterator::operator*; //[t75]
//@}
/**
* @name Manipulations
*/
//@{
const_reverse_iterator &operator=(const const_reverse_iterator &r) //[t75]
{ iterator_type::operator=(r); return *this; }
const_reverse_iterator operator++() //[t75]
{ iterator_type::operator--(); return *this; }
const_reverse_iterator operator++(int); //[t75]
const_reverse_iterator &operator--() //[t75]
{ iterator_type::operator++(); return *this; }
const_reverse_iterator operator--(int); //[t75]
const_reverse_iterator &operator+=(difference_type i) //[t75]
{ iterator_type::operator-=(i); return *this; }
const_reverse_iterator &operator-=(difference_type i) //[t75]
{ iterator_type::operator+=(i); return *this; }
//@}
/**
* @name Arithmetic operators
*/
//@{
const_reverse_iterator operator+(difference_type i) const //[t75]
{ return const_reverse_iterator(base()-i); }
const_reverse_iterator operator-(difference_type i) //[t75]
{ return const_reverse_iterator(base()+i); }
difference_type operator-(const const_reverse_iterator &rhs) const //[t75]
{ return rhs.const_iterator::operator-(*this); }
//@}
/**
* @name Comparisons
*/
//@{
bool operator==(const const_reverse_iterator &rhs) const throw () //[t75]
{ return iterator_type::operator==(rhs); }
bool operator!=(const const_reverse_iterator &rhs) const throw () //[t75]
{ return !operator==(rhs); }
bool operator<(const const_reverse_iterator &rhs) const //[t75]
{ return iterator_type::operator>(rhs); }
bool operator<=(const const_reverse_iterator &rhs) const //[t75]
{ return iterator_type::operator>=(rhs); }
bool operator>(const const_reverse_iterator &rhs) const //[t75]
{ return iterator_type::operator<(rhs); }
bool operator>=(const const_reverse_iterator &rhs) const //[t75]
{ return iterator_type::operator<=(rhs); }
//@}
};
typedef const_reverse_iterator reverse_iterator;
class PQXX_LIBEXPORT const_fielditerator :
public PGSTD::iterator<PGSTD::random_access_iterator_tag,
const field,
tuple::size_type>,
public field
{
typedef PGSTD::iterator<PGSTD::random_access_iterator_tag,
const field,
tuple::size_type> it;
public:
using it::pointer;
typedef tuple::size_type size_type;
typedef tuple::difference_type difference_type;
typedef field reference;
const_fielditerator(const tuple &T, tuple::size_type C) throw () : //[t82]
field(T, C) {}
const_fielditerator(const field &F) throw () : field(F) {} //[t82]
/**
* @name Dereferencing operators
*/
//@{
pointer operator->() const { return this; } //[t82]
reference operator*() const { return field(*this); } //[t82]
//@}
/**
* @name Manipulations
*/
//@{
const_fielditerator operator++(int); //[t82]
const_fielditerator &operator++() { ++m_col; return *this; } //[t82]
const_fielditerator operator--(int); //[t82]
const_fielditerator &operator--() { --m_col; return *this; } //[t82]
const_fielditerator &operator+=(difference_type i) //[t82]
{ m_col = size_type(difference_type(m_col) + i); return *this; }
const_fielditerator &operator-=(difference_type i) //[t82]
{ m_col = size_type(difference_type(m_col) - i); return *this; }
//@}
/**
* @name Comparisons
*/
//@{
bool operator==(const const_fielditerator &i) const //[t82]
{return col()==i.col();}
bool operator!=(const const_fielditerator &i) const //[t82]
{return col()!=i.col();}
bool operator<(const const_fielditerator &i) const //[t82]
{return col()<i.col();}
bool operator<=(const const_fielditerator &i) const //[t82]
{return col()<=i.col();}
bool operator>(const const_fielditerator &i) const //[t82]
{return col()>i.col();}
bool operator>=(const const_fielditerator &i) const //[t82]
{return col()>=i.col();}
//@}
/**
* @name Arithmetic operators
*/
//@{
inline const_fielditerator operator+(difference_type) const; //[t82]
friend const_fielditerator operator+(difference_type,
const_fielditerator); //[t82]
inline const_fielditerator operator-(difference_type) const; //[t82]
inline difference_type operator-(const_fielditerator) const; //[t82]
//@}
};
class PQXX_LIBEXPORT const_reverse_fielditerator : private const_fielditerator
{
public:
typedef const_fielditerator super;
typedef const_fielditerator iterator_type;
using iterator_type::iterator_category;
using iterator_type::difference_type;
using iterator_type::pointer;
#ifndef _MSC_VER
using iterator_type::value_type;
using iterator_type::reference;
#else
// Workaround for Visual C++.NET 2003, which has access problems
typedef field value_type;
typedef const field &reference;
#endif
const_reverse_fielditerator(const const_reverse_fielditerator &r) : //[t82]
const_fielditerator(r) {}
explicit
const_reverse_fielditerator(const super &rhs) throw() : //[t82]
const_fielditerator(rhs) { super::operator--(); }
iterator_type base() const throw (); //[t82]
/**
* @name Dereferencing operators
*/
//@{
using iterator_type::operator->; //[t82]
using iterator_type::operator*; //[t82]
//@}
/**
* @name Manipulations
*/
//@{
const_reverse_fielditerator &
operator=(const const_reverse_fielditerator &r) //[t82]
{ iterator_type::operator=(r); return *this; }
const_reverse_fielditerator operator++() //[t82]
{ iterator_type::operator--(); return *this; }
const_reverse_fielditerator operator++(int); //[t82]
const_reverse_fielditerator &operator--() //[t82]
{ iterator_type::operator++(); return *this; }
const_reverse_fielditerator operator--(int); //[t82]
const_reverse_fielditerator &operator+=(difference_type i) //[t82]
{ iterator_type::operator-=(i); return *this; }
const_reverse_fielditerator &operator-=(difference_type i) //[t82]
{ iterator_type::operator+=(i); return *this; }
//@}
/**
* @name Arithmetic operators
*/
//@{
const_reverse_fielditerator operator+(difference_type i) const //[t82]
{ return const_reverse_fielditerator(base()-i); }
const_reverse_fielditerator operator-(difference_type i) //[t82]
{ return const_reverse_fielditerator(base()+i); }
difference_type
operator-(const const_reverse_fielditerator &rhs) const //[t82]
{ return rhs.const_fielditerator::operator-(*this); }
//@}
/**
* @name Comparisons
*/
//@{
bool
operator==(const const_reverse_fielditerator &rhs) const throw () //[t82]
{ return iterator_type::operator==(rhs); }
bool
operator!=(const const_reverse_fielditerator &rhs) const throw () //[t82]
{ return !operator==(rhs); }
bool operator<(const const_reverse_fielditerator &rhs) const //[t82]
{ return iterator_type::operator>(rhs); }
bool operator<=(const const_reverse_fielditerator &rhs) const //[t82]
{ return iterator_type::operator>=(rhs); }
bool operator>(const const_reverse_fielditerator &rhs) const //[t82]
{ return iterator_type::operator<(rhs); }
bool operator>=(const const_reverse_fielditerator &rhs) const //[t82]
{ return iterator_type::operator<=(rhs); }
//@}
};
result() throw () : super(), m_data(0) {} //[t3]
result(const result &rhs) throw () : //[t1]
super(rhs), m_data(rhs.m_data) {}
result &operator=(const result &rhs) throw () //[t10]
{ super::operator=(rhs); m_data=rhs.m_data; return *this; }
/**
* @name Comparisons
*/
//@{
bool operator==(const result &) const throw (); //[t70]
bool operator!=(const result &rhs) const throw () //[t70]
{ return !operator==(rhs); }
//@}
const_reverse_iterator rbegin() const //[t75]
{ return const_reverse_iterator(end()); }
const_reverse_iterator rend() const //[t75]
{ return const_reverse_iterator(begin()); }
const_iterator begin() const throw () //[t1]
{ return const_iterator(this, 0); }
inline const_iterator end() const throw (); //[t1]
reference front() const throw () { return tuple(this,0); } //[t74]
reference back() const throw () {return tuple(this,size()-1);} //[t75]
size_type size() const throw (); //[t2]
bool empty() const throw (); //[t11]
size_type capacity() const throw () { return size(); } //[t20]
void swap(result &) throw (); //[t77]
const tuple operator[](size_type i) const throw () //[t2]
{ return tuple(this, i); }
const tuple at(size_type) const throw (range_error); //[t10]
void clear() throw () { super::reset(); m_data = 0; } //[t20]
/**
* @name Column information
*/
//@{
/// Number of columns in result
tuple::size_type columns() const throw (); //[t11]
/// Number of given column (throws exception if it doesn't exist)
tuple::size_type column_number(const char ColName[]) const; //[t11]
/// Number of given column (throws exception if it doesn't exist)
tuple::size_type column_number(const PGSTD::string &Name) const //[t11]
{return column_number(Name.c_str());}
/// Name of column with this number (throws exception if it doesn't exist)
const char *column_name(tuple::size_type Number) const; //[t11]
/// Type of given column
oid column_type(tuple::size_type ColNum) const; //[t7]
/// Type of given column
oid column_type(int ColNum) const //[t7]
{ return column_type(tuple::size_type(ColNum)); }
/// Type of given column
oid column_type(const PGSTD::string &ColName) const //[t7]
{ return column_type(column_number(ColName)); }
/// Type of given column
oid column_type(const char ColName[]) const //[t7]
{ return column_type(column_number(ColName)); }
/// What table did this column come from? Requires PostgreSQL 7.4 C API.
/** Only defined if the libpqxx library was compiled against a libpq
* version that supports the @c PQftable function.
*
* If you get a link error saying this function is undefined, that must be
* because libpqxx was compiled against an older version of libpq. The
* @c PQftable function first became available in PostgreSQL 7.4.
*/
oid column_table(tuple::size_type ColNum) const; //[t2]
/// What table did this column come from? Requires PostgreSQL 7.4 C API.
/** Only defined if the libpqxx library was compiled against a libpq
* version that supports the @c PQftable function.
*
* If you get a link error saying this function is undefined, that must be
* because libpqxx was compiled against an older version of libpq. The
* @c PQftable function first became available in PostgreSQL 7.4.
*/
oid column_table(int ColNum) const //[t2]
{ return column_table(tuple::size_type(ColNum)); }
/// What table did this column come from? Requires PostgreSQL 7.4 C API.
/** Only defined if the libpqxx library was compiled against a libpq
* version that supports the @c PQftable function.
*
* If you get a link error saying this function is undefined, that must be
* because libpqxx was compiled against an older version of libpq. The
* @c PQftable function first became available in PostgreSQL 7.4.
*/
oid column_table(const PGSTD::string &ColName) const //[t2]
{ return column_table(column_number(ColName)); }
/// What column in its table did this column come from?
tuple::size_type table_column(tuple::size_type ColNum) const; //[t93]
/// What column in its table did this column come from?
tuple::size_type table_column(int ColNum) const //[t93]
{ return table_column(tuple::size_type(ColNum)); }
/// What column in its table did this column come from?
tuple::size_type table_column(const PGSTD::string &ColName) const //[t93]
{ return table_column(column_number(ColName)); }
//@}
/// Query that produced this result, if available (empty string otherwise)
const PGSTD::string &query() const throw (); //[t70]
/// If command was @c INSERT of 1 row, return oid of inserted row
/** @return Identifier of inserted row if exactly one row was inserted, or
* oid_none otherwise.
*/
oid inserted_oid() const; //[t13]
/// If command was @c INSERT, @c UPDATE, or @c DELETE: number of affected rows
/** @return Number of affected rows if last command was @c INSERT, @c UPDATE,
* or @c DELETE; zero for all other commands.
*/
size_type affected_rows() const; //[t7]
private:
friend class pqxx::result::field;
const char *GetValue(size_type Row, tuple::size_type Col) const;
bool GetIsNull(size_type Row, tuple::size_type Col) const;
field::size_type GetLength(size_type, tuple::size_type) const throw ();
friend class pqxx::internal::gate::result_creation;
result(internal::pq::PGresult *rhs,
int protocol,
const PGSTD::string &Query,
int encoding_code);
void PQXX_PRIVATE CheckStatus() const;
friend class pqxx::internal::gate::result_connection;
bool operator!() const throw () { return !m_data; }
operator bool() const throw () { return m_data != 0; }
void PQXX_PRIVATE ThrowSQLError(const PGSTD::string &Err,
const PGSTD::string &Query) const;
int PQXX_PRIVATE errorposition() const throw ();
PGSTD::string PQXX_PRIVATE StatusError() const;
friend class pqxx::internal::gate::result_sql_cursor;
const char *CmdStatus() const throw ();
/// Shortcut: pointer to result data
pqxx::internal::pq::PGresult *m_data;
static const PGSTD::string PQXX_PRIVATE s_empty_string;
};
/// Write a result field to any type of stream
/** This can be convenient when writing a field to an output stream. More
* importantly, it lets you write a field to e.g. a @c stringstream which you
* can then use to read, format and convert the field in ways that to() does not
* support.
*
* Example: parse a field into a variable of the nonstandard
* "<tt>long long</tt>" type.
*
* @code
* extern result R;
* long long L;
* stringstream S;
*
* // Write field's string into S
* S << R[0][0];
*
* // Parse contents of S into L
* S >> L;
* @endcode
*/
template<typename CHAR>
inline PGSTD::basic_ostream<CHAR> &operator<<(
PGSTD::basic_ostream<CHAR> &S, const pqxx::result::field &F) //[t46]
{
S.write(F.c_str(), F.size());
return S;
}
/// Convert a field's string contents to another type
template<typename T>
inline void from_string(const result::field &F, T &Obj) //[t46]
{ from_string(F.c_str(), Obj, F.size()); }
/// Convert a field to a string
template<>
inline PGSTD::string to_string(const result::field &Obj) //[t74]
{ return PGSTD::string(Obj.c_str(), Obj.size()); }
/// Specialization: <tt>to(string &)</tt>.
template<>
inline bool result::field::to<PGSTD::string>(PGSTD::string &Obj) const
{
const char *const bytes = c_str();
if (!bytes[0] && is_null()) return false;
Obj = PGSTD::string(bytes, size());
return true;
}
/// Specialization: <tt>to(const char *&)</tt>.
/** The buffer has the same lifetime as the data in this result (i.e. of this
* result object, or the last remaining one copied from it etc.), so take care
* not to use it after the last result object referring to this query result is
* destroyed.
*/
template<>
inline bool result::field::to<const char *>(const char *&Obj) const
{
if (is_null()) return false;
Obj = c_str();
return true;
}
inline result::tuple::const_reverse_iterator result::tuple::rbegin() const
{ return const_reverse_fielditerator(end()); }
inline result::tuple::const_reverse_iterator result::tuple::rend() const
{ return const_reverse_fielditerator(begin()); }
inline result::const_iterator
result::const_iterator::operator+(difference_type o) const
{
return const_iterator(m_Home, size_type(difference_type(m_Index) + o));
}
inline result::const_iterator
operator+(result::const_iterator::difference_type o, result::const_iterator i)
{ return i + o; }
inline result::const_iterator
result::const_iterator::operator-(difference_type o) const
{
return const_iterator(m_Home, size_type(difference_type(m_Index) - o));
}
inline result::const_iterator::difference_type
result::const_iterator::operator-(const_iterator i) const
{ return difference_type(num()) - difference_type(i.num()); }
inline result::const_iterator result::end() const throw ()
{ return const_iterator(this, size()); }
inline result::const_reverse_iterator
operator+(result::const_reverse_iterator::difference_type n,
const result::const_reverse_iterator &i)
{ return result::const_reverse_iterator(i.base() - n); }
inline result::const_fielditerator
result::const_fielditerator::operator+(difference_type o) const
{
return const_fielditerator(m_tup, size_type(difference_type(col()) + o));
}
inline result::const_fielditerator
operator+(result::const_fielditerator::difference_type o,
result::const_fielditerator i)
{ return i + o; }
inline result::const_fielditerator
result::const_fielditerator::operator-(difference_type o) const
{
return const_fielditerator(m_tup, size_type(difference_type(col()) - o));
}
inline result::const_fielditerator::difference_type
result::const_fielditerator::operator-(const_fielditerator i) const
{ return difference_type(num()) - difference_type(i.num()); }
template<typename CHAR=char, typename TRAITS=PGSTD::char_traits<CHAR> >
class field_streambuf :
#ifdef PQXX_HAVE_STREAMBUF
public PGSTD::basic_streambuf<CHAR, TRAITS>
#else
public PGSTD::streambuf
#endif
{
public:
typedef CHAR char_type;
typedef TRAITS traits_type;
typedef typename traits_type::int_type int_type;
#ifdef PQXX_HAVE_STREAMBUF
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
#else
typedef streamoff off_type;
typedef streampos pos_type;
#endif
typedef PGSTD::ios::openmode openmode;
typedef PGSTD::ios::seekdir seekdir;
explicit field_streambuf(const result::field &F) : //[t74]
m_Field(F)
{
initialize();
}
#ifdef PQXX_HAVE_STREAMBUF
protected:
#endif
virtual int sync() { return traits_type::eof(); }
protected:
virtual pos_type seekoff(off_type, seekdir, openmode)
{ return traits_type::eof(); }
virtual pos_type seekpos(pos_type, openmode) {return traits_type::eof();}
virtual int_type overflow(int_type) { return traits_type::eof(); }
virtual int_type underflow() { return traits_type::eof(); }
private:
const result::field &m_Field;
int_type initialize()
{
char_type *G =
reinterpret_cast<char_type *>(const_cast<char *>(m_Field.c_str()));
this->setg(G, G, G + m_Field.size());
return int_type(m_Field.size());
}
};
/// Input stream that gets its data from a result field
/** Use this class exactly as you would any other istream to read data from a
* field. All formatting and streaming operations of @c std::istream are
* supported. What you'll typically want to use, however, is the fieldstream
* typedef (which defines a basic_fieldstream for @c char). This is similar to
* how e.g. @c std::ifstream relates to @c std::basic_ifstream.
*
* This class has only been tested for the char type (and its default traits).
*/
template<typename CHAR=char, typename TRAITS=PGSTD::char_traits<CHAR> >
class basic_fieldstream :
#ifdef PQXX_HAVE_STREAMBUF
public PGSTD::basic_istream<CHAR, TRAITS>
#else
public PGSTD::istream
#endif
{
#ifdef PQXX_HAVE_STREAMBUF
typedef PGSTD::basic_istream<CHAR, TRAITS> super;
#else
typedef PGSTD::istream super;
#endif
public:
typedef CHAR char_type;
typedef TRAITS traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
basic_fieldstream(const result::field &F) : super(0), m_Buf(F)
{ super::init(&m_Buf); }
private:
field_streambuf<CHAR, TRAITS> m_Buf;
};
typedef basic_fieldstream<char> fieldstream;
} // namespace pqxx
/*
[1] Scott Meyers, in one of his essential books, "Effective C++" and "More
Effective C++", points out that it is good style to have any class containing
a member of pointer type define a destructor--just to show that it knows what it
is doing with the pointer. This helps prevent nasty memory leak / double
deletion bugs typically resulting from programmers' omission to deal with such
issues in their destructors.
The @c -Weffc++ option in gcc generates warnings for noncompliance with Scott's
style guidelines, and hence necessitates the definition of this destructor,
trivial as it may be.
*/
#include "pqxx/compiler-internal-post.hxx"
#endif
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