tablereader.hxx

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/*-------------------------------------------------------------------------
 *
 *   FILE
 *      pqxx/tablereader.hxx
 *
 *   DESCRIPTION
 *      definition of the pqxx::tablereader class.
 *   pqxx::tablereader enables optimized batch reads from a database table
 *   DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/tablereader instead.
 *
 * Copyright (c) 2001-2004, 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.
 *
 *-------------------------------------------------------------------------
 */
#include "pqxx/result"
#include "pqxx/tablestream"

/* Methods tested in eg. self-test program test001 are marked with "//[t1]"
 */

namespace pqxx
{


class PQXX_LIBEXPORT tablereader : public tablestream
{
public:
  tablereader(transaction_base &, 
      const PGSTD::string &RName,
      const PGSTD::string &Null=PGSTD::string());                       //[t6]


  template<typename ITER>
  tablereader(transaction_base &, 
      const PGSTD::string &RName,
      ITER begincolumns,
      ITER endcolumns,
      const PGSTD::string &Null=PGSTD::string());                       //[t80]

  ~tablereader() throw ();                                              //[t6]

  template<typename TUPLE> tablereader &operator>>(TUPLE &);            //[t8]

  operator bool() const throw () { return !m_Done; }                    //[t6]
  bool operator!() const throw () { return m_Done; }                    //[t6]


  bool get_raw_line(PGSTD::string &Line);                               //[t8]

  template<typename TUPLE> 
  void tokenize(PGSTD::string, TUPLE &) const;                          //[t8]


  virtual void complete();                                              //[t8]

#ifdef PQXX_DEPRECATED_HEADERS

  bool GetRawLine(PGSTD::string &L) { return get_raw_line(L); }
  template<typename TUPLE> void Tokenize(PGSTD::string L, TUPLE &T) const
        { tokenize(L, T); }
#endif

private:
  void setup(transaction_base &T,
      const PGSTD::string &RName,
      const PGSTD::string &Columns=PGSTD::string());
  void reader_close();
  PGSTD::string extract_field(const PGSTD::string &, 
      PGSTD::string::size_type &) const;

  bool m_Done;
};


// TODO: Find meaningful definition of input iterator


template<typename ITER> inline
tablereader::tablereader(transaction_base &T, 
    const PGSTD::string &RName,
    ITER begincolumns,
    ITER endcolumns,
    const PGSTD::string &Null) :
  tablestream(T, RName, Null, "tablereader"),
  m_Done(true)
{
  setup(T, RName, columnlist(begincolumns, endcolumns));
}


template<typename TUPLE> 
inline void tablereader::tokenize(PGSTD::string Line, TUPLE &T) const
{
  PGSTD::back_insert_iterator<TUPLE> ins = PGSTD::back_inserter(T);

  // Filter and tokenize line, inserting tokens at end of T
  PGSTD::string::size_type here=0;
  while (here < Line.size()) *ins++ = extract_field(Line, here);
}


template<typename TUPLE> 
inline tablereader &pqxx::tablereader::operator>>(TUPLE &T)
{
  PGSTD::string Line;
  if (get_raw_line(Line)) tokenize(Line, T);
  return *this;
}


} // namespace pqxx

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