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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) 2001-2003, 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 test1 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 
00067 class PQXX_LIBEXPORT Cursor
00068 {
00069 public:
00070   typedef result::size_type size_type;
00071 
00072   enum pos { pos_unknown = -1, pos_start = 0 };
00073 
00075   struct PQXX_LIBEXPORT unknown_position : PGSTD::runtime_error
00076   {
00077     unknown_position(const PGSTD::string &cursorname) :
00078       PGSTD::runtime_error("Position for cursor '" + cursorname + "' "
00079                            "is unknown") 
00080     {
00081     }
00082   };
00083 
00085 
00093   template<typename TRANSACTION> 
00094     Cursor(TRANSACTION &T,
00095            const char Query[], 
00096            const PGSTD::string &BaseName="cur",
00097            size_type Count=NEXT()) :                                    //[t3]
00098       m_Trans(T),
00099       m_Name(),
00100       m_Count(Count),
00101       m_Done(false),
00102       m_Pos(pos_start),
00103       m_Size(pos_unknown)
00104   {
00105     // Trigger build error if T has insufficient isolation level
00106     error_permitted_isolation_level(PQXX_TYPENAME TRANSACTION::isolation_tag());
00107     init(BaseName, Query);
00108   }
00109 
00111 
00141   template<typename TRANSACTION>
00142     Cursor(TRANSACTION &T,
00143            const result::field &Name,
00144            size_type Count=NEXT()) :                                    //[t45]
00145       m_Trans(T),
00146       m_Name(Name.c_str()),
00147       m_Count(Count),
00148       m_Done(false),
00149       m_Pos(pos_unknown),
00150       m_Size(pos_unknown)
00151   {
00152     // Trigger build error if T has insufficient isolation level
00153     error_permitted_isolation_level(PQXX_TYPENAME TRANSACTION::isolation_tag());
00154   }
00155 
00157   size_type SetCount(size_type);                                        //[t19]
00158 
00160 
00169   result Fetch(size_type Count);                                        //[t19]
00170 
00172 
00180   size_type Move(size_type Count);                                      //[t42]
00181 
00182   void MoveTo(size_type);                                               //[t44]
00183 
00185 
00189   static size_type ALL() throw ();                                      //[t3]
00190 
00192   static size_type NEXT() throw () { return 1; }                        //[t19]
00193 
00195   static size_type PRIOR() throw () { return -1; }                      //[t19]
00196 
00199 
00203   static size_type BACKWARD_ALL() throw ();                             //[t19]
00204 
00206 
00213   Cursor &operator>>(result &);                                         //[t3]
00214 
00216   operator bool() const throw () { return !m_Done; }                    //[t3]
00218   bool operator!() const throw () { return m_Done; }                    //[t3]
00219 
00221   Cursor &operator+=(size_type N) { Move(N); return *this;}             //[t19]
00223   Cursor &operator-=(size_type N) { Move(-N); return *this;}            //[t19]
00224 
00226 
00237   size_type size() const throw () { return m_Size; }                    //[t44]
00238 
00240 
00247   size_type Pos() const throw (unknown_position)                        //[t43]
00248   { if (m_Pos==pos_unknown) throw unknown_position(m_Name); return m_Pos; }
00249 
00250 
00251 private:
00252   static PGSTD::string OffsetString(size_type);
00253   void init(const PGSTD::string &BaseName, const char Query[]);
00254   PGSTD::string MakeFetchCmd(size_type) const;
00255   size_type NormalizedMove(size_type Intended, size_type Actual);
00256 
00257 #ifndef PQXX_WORKAROUND_VC7
00258 
00259 
00263   template<typename ISOLATIONTAG> 
00264     static inline void error_permitted_isolation_level(ISOLATIONTAG) throw();
00265 #else
00266   // Incorrect, but needed to compile with Visual C++ 7
00267   template<> static inline void 
00268     error_permitted_isolation_level(isolation_traits<serializable>) throw ();
00269 #endif
00270 
00271   transaction_base &m_Trans;
00272   PGSTD::string m_Name;
00273   size_type m_Count;
00274   bool m_Done;
00275   size_type m_Pos;
00276   size_type m_Size;
00277 
00278   // Not allowed:
00279   Cursor(const Cursor &);
00280   Cursor &operator=(const Cursor &);
00281 };
00282 
00283 template<> inline void 
00284 Cursor::error_permitted_isolation_level(isolation_traits<serializable>) throw ()
00285         {}
00286 
00287 }
00288 
00289 #endif
00290 

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