Main Page   Namespace List   Class Hierarchy   Alphabetical List   Compound List   File List   Namespace Members   Compound Members   File Members   Related Pages  

tablereader.h

Go to the documentation of this file.
00001 /*-------------------------------------------------------------------------
00002  *
00003  *   FILE
00004  *      pqxx/tablereader.h
00005  *
00006  *   DESCRIPTION
00007  *      definition of the pqxx::TableReader class.
00008  *   pqxx::TableReader enables optimized batch reads from a database table
00009  *
00010  * Copyright (c) 2001-2003, Jeroen T. Vermeulen <jtv@xs4all.nl>
00011  *
00012  *-------------------------------------------------------------------------
00013  */
00014 #ifndef PQXX_TABLEREADER_H
00015 #define PQXX_TABLEREADER_H
00016 
00017 #include <string>
00018 
00019 #include "pqxx/result.h"
00020 #include "pqxx/tablestream.h"
00021 
00022 /* Methods tested in eg. self-test program test1 are marked with "//[t1]"
00023  */
00024 
00025 
00026 namespace pqxx
00027 {
00028 
00030 
00042 class PQXX_LIBEXPORT TableReader : public TableStream
00043 {
00044 public:
00045   TableReader(Transaction_base &, const PGSTD::string &RName);          //[t6]
00046   ~TableReader();                                                       //[t6]
00047 
00048   template<typename TUPLE> TableReader &operator>>(TUPLE &);            //[t8]
00049 
00050   operator bool() const throw () { return !m_Done; }                    //[t6]
00051   bool operator!() const throw () { return m_Done; }                    //[t6]
00052 
00054 
00057   bool GetRawLine(PGSTD::string &Line);                                 //[t8]
00058 
00059   template<typename TUPLE> 
00060   void Tokenize(PGSTD::string, TUPLE &) const;                          //[t8]
00061 
00062 private:
00063   bool m_Done;
00064 };
00065 
00066 }
00067 
00068 // TODO: Find meaningful definition of input iterator
00069 
00070 
00071 template<typename TUPLE> 
00072 inline void pqxx::TableReader::Tokenize(PGSTD::string Line, 
00073                                         TUPLE &T) const
00074 {
00075   PGSTD::back_insert_iterator<TUPLE> ins = PGSTD::back_inserter(T);
00076 
00077   // Filter and tokenize line, inserting tokens at end of T
00078   PGSTD::string::size_type token = 0;
00079   for (PGSTD::string::size_type i=0; i < Line.size(); ++i)
00080   {
00081     switch (Line[i])
00082     {
00083     case '\t': // End of token
00084       *ins++ = PGSTD::string(Line, token, i-token);
00085       token = i+1;
00086       break;
00087 
00088     case '\\':
00089       // Ignore the backslash and accept literally whatever comes after it 
00090       if ((i+1) >= Line.size()) 
00091         throw PGSTD::runtime_error("Row ends in backslash");
00092 
00093       switch (Line[i+1])
00094       {
00095       case 'N':
00096         // This is a \N, signifying a NULL value.
00097         Line.replace(i, 2, NullStr());
00098         i += NullStr().size() - 1;
00099         break;
00100       
00101       case 't':
00102         Line.replace(i++, 2, "\t");
00103         break;
00104 
00105       case 'n':
00106         Line.replace(i++, 2, "\n");
00107         break;
00108 
00109       default:
00110         Line.erase(i, 1);
00111       }
00112       break;
00113     }
00114   }
00115 
00116   *ins++ = PGSTD::string(Line, token);
00117 }
00118 
00119 
00120 template<typename TUPLE> 
00121 inline pqxx::TableReader &pqxx::TableReader::operator>>(TUPLE &T)
00122 {
00123   PGSTD::string Line;
00124   if (GetRawLine(Line)) Tokenize(Line, T);
00125   return *this;
00126 }
00127 
00128 
00129 
00130 #endif
00131 

Generated on Sat May 24 02:03:12 2003 for libpqxx by doxygen1.3-rc3