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cursor.h

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00001 /*-------------------------------------------------------------------------
00002  *
00003  *   FILE
00004  *      pqxx/cursor.h
00005  *
00006  *   DESCRIPTION
00007  *      definition of the pqxx::Cursor class.
00008  *   pqxx::Cursor represents a database cursor.
00009  *
00010  * Copyright (c) 2001-2004, Jeroen T. Vermeulen <jtv@xs4all.nl>
00011  *
00012  * See COPYING for copyright license.  If you did not receive a file called
00013  * COPYING with this source code, please notify the distributor of this mistake,
00014  * or contact the author.
00015  *
00016  *-------------------------------------------------------------------------
00017  */
00018 #ifndef PQXX_CURSOR_H
00019 #define PQXX_CURSOR_H
00020 
00021 #include "pqxx/result.h"
00022 #include "pqxx/transaction_base.h"
00023 #include "pqxx/util.h"
00024 
00025 /* Methods tested in eg. self-test program test001 are marked with "//[t1]"
00026  */
00027 
00028 namespace pqxx
00029 {
00030 class result;
00031 
00032 
00033 // Work around bug in CodeWarrior 8.3
00034 #ifdef __MWERKS__
00035 #pragma defer_defarg_parsing on
00036 #endif
00037 
00038 
00040 
00070 class PQXX_LIBEXPORT Cursor
00071 {
00072   enum { dist_next=1 };
00073 
00074 public:
00075   typedef result::size_type size_type;
00076 
00077   enum pos { pos_unknown = -1, pos_start = 0 };
00078 
00080   struct PQXX_LIBEXPORT unknown_position : PGSTD::runtime_error
00081   {
00082     unknown_position(const PGSTD::string &cursorname) :
00083       PGSTD::runtime_error("Position for cursor '" + cursorname + "' "
00084                            "is unknown") 
00085     {
00086     }
00087   };
00088 
00090 
00098   template<typename TRANSACTION> 
00099     Cursor(TRANSACTION &T,
00100            const char Query[], 
00101            const PGSTD::string &BaseName="cur",
00102            size_type Count=dist_next) :                                 //[t3]
00103       m_Trans(T),
00104       m_Name(),
00105       m_Count(Count),
00106       m_Done(false),
00107       m_Pos(pos_start),
00108       m_Size(pos_unknown)
00109   {
00110     // Trigger build error if T has insufficient isolation level
00111     error_permitted_isolation_level(PQXX_TYPENAME TRANSACTION::isolation_tag());
00112     init(BaseName, Query);
00113   }
00114 
00116 
00146   template<typename TRANSACTION>
00147     Cursor(TRANSACTION &T,
00148            const result::field &Name,
00149            size_type Count=dist_next) :                                 //[t45]
00150       m_Trans(T),
00151       m_Name(Name.c_str()),
00152       m_Count(Count),
00153       m_Done(false),
00154       m_Pos(pos_unknown),
00155       m_Size(pos_unknown)
00156   {
00157     // Trigger build error if T has insufficient isolation level
00158     error_permitted_isolation_level(PQXX_TYPENAME TRANSACTION::isolation_tag());
00159   }
00160 
00162   size_type SetCount(size_type);                                        //[t19]
00163 
00165 
00174   result Fetch(size_type Count);                                        //[t19]
00175 
00177 
00185   size_type Move(size_type Count);                                      //[t42]
00186 
00187   void MoveTo(size_type);                                               //[t44]
00188 
00190 
00194   static size_type ALL() throw ();                                      //[t3]
00195 
00197   static size_type NEXT() throw () { return dist_next; }                //[t19]
00198 
00200   static size_type PRIOR() throw () { return -1; }                      //[t19]
00201 
00204 
00208   static size_type BACKWARD_ALL() throw ();                             //[t19]
00209 
00211 
00218   Cursor &operator>>(result &);                                         //[t3]
00219 
00221   operator bool() const throw () { return !m_Done; }                    //[t3]
00223   bool operator!() const throw () { return m_Done; }                    //[t3]
00224 
00226   Cursor &operator+=(size_type N) { Move(N); return *this;}             //[t19]
00228   Cursor &operator-=(size_type N) { Move(-N); return *this;}            //[t19]
00229 
00231 
00242   size_type size() const throw () { return m_Size; }                    //[t44]
00243 
00245 
00252   size_type Pos() const throw (unknown_position)                        //[t43]
00253   { if (m_Pos==pos_unknown) throw unknown_position(m_Name); return m_Pos; }
00254 
00255 
00256 private:
00257   static PGSTD::string OffsetString(size_type);
00258   void init(const PGSTD::string &BaseName, const char Query[]);
00259   PGSTD::string MakeFetchCmd(size_type) const;
00260   size_type NormalizedMove(size_type Intended, size_type Actual);
00261 
00262 #ifndef PQXX_WORKAROUND_VC7
00263 
00264 
00268   template<typename ISOLATIONTAG> 
00269     static inline void error_permitted_isolation_level(ISOLATIONTAG) throw();
00270 
00271 #if defined(__SUNPRO_CC)
00272   // Incorrect, but needed to compile with Sun CC
00273   template<> static void 
00274     error_permitted_level(isolation_traits<serializable>) throw() {}
00275 #endif  // __SUNPRO_CC
00276 #else
00277   // Incorrect, but needed to compile with Visual C++ 7
00278   template<> static inline void 
00279     error_permitted_isolation_level(isolation_traits<serializable>) throw ();
00280 #endif
00281 
00282   transaction_base &m_Trans;
00283   PGSTD::string m_Name;
00284   size_type m_Count;
00285   bool m_Done;
00286   size_type m_Pos;
00287   size_type m_Size;
00288 
00289   // Not allowed:
00290   Cursor(const Cursor &);
00291   Cursor &operator=(const Cursor &);
00292 };
00293 
00294 template<> inline void 
00295 Cursor::error_permitted_isolation_level(isolation_traits<serializable>) throw ()
00296         {}
00297 
00298 } // namespace pqxx
00299 
00300 #endif
00301 

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