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util.h

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00001 /*-------------------------------------------------------------------------
00002  *
00003  *   FILE
00004  *      pqxx/util.h
00005  *
00006  *   DESCRIPTION
00007  *      Various utility definitions for libpqxx
00008  *
00009  * Copyright (c) 2001-2002, Jeroen T. Vermeulen <jtv@xs4all.nl>
00010  *
00011  *-------------------------------------------------------------------------
00012  */
00013 #ifndef PQXX_UTIL_H
00014 #define PQXX_UTIL_H
00015 
00016 #include "pqxx/compiler.h"
00017 
00018 #include <cstdio>
00019 #include <stdexcept>
00020 #include <string>
00021 #include <typeinfo>
00022 
00023 extern "C"
00024 {
00025 #include "libpq-fe.h"
00026 }
00027 
00028 
00029 namespace pqxx
00030 {
00031 typedef long Result_size_type;
00032 typedef int Tuple_size_type;
00033 
00036 template<typename T> inline const char *FmtString(T);
00037 
00038 // Not implemented to prevent accidents with irregular meaning of argument:
00039 // template<> inline const char *FmtString(const char *&) { return "%s"; }
00040 
00041 template<> inline const char *FmtString(int)           { return  "%i"; }
00042 template<> inline const char *FmtString(long)          { return "%li"; }
00043 template<> inline const char *FmtString(unsigned)      { return  "%u"; }
00044 template<> inline const char *FmtString(unsigned long) { return "%lu"; }
00045 template<> inline const char *FmtString(float)         { return  "%f"; }
00046 template<> inline const char *FmtString(double)        { return "%lf"; }
00047 template<> inline const char *FmtString(char)          { return  "%c"; }
00048 template<> inline const char *FmtString(unsigned char) { return  "%c"; }
00049 
00050 
00052 template<typename T> inline PGSTD::string ToString(const T &Obj)
00053 {
00054   // TODO: Find a decent way to determine max string length at compile time!
00055   char Buf[500];
00056   sprintf(Buf, FmtString(Obj), Obj);
00057   return PGSTD::string(Buf);
00058 }
00059 
00060 template<> inline PGSTD::string ToString(const PGSTD::string &Obj) {return Obj;}
00061 template<> inline PGSTD::string ToString(const char *const &Obj) { return Obj; }
00062 
00063 template<> inline PGSTD::string ToString(const bool &Obj) 
00064 { 
00065   return ToString(unsigned(Obj));
00066 }
00067 
00068 template<> inline PGSTD::string ToString(const short &Obj)
00069 {
00070   return ToString(int(Obj));
00071 }
00072 
00073 template<> inline PGSTD::string ToString(const unsigned short &Obj)
00074 {
00075   return ToString(unsigned(Obj));
00076 }
00077 
00078 
00079 template<typename T> inline void FromString(const char Str[], T &Obj)
00080 {
00081   if (!Str) throw PGSTD::runtime_error("Attempt to convert NULL string to " +
00082                                      PGSTD::string(typeid(T).name()));
00083 
00084   if (sscanf(Str, FmtString(Obj), &Obj) != 1)
00085     throw PGSTD::runtime_error("Cannot convert value '" + 
00086                              PGSTD::string(Str) + 
00087                              "' to " + typeid(T).name());
00088 }
00089 
00090 
00091 template<> inline void FromString(const char Str[], PGSTD::string &Obj)
00092 {
00093   if (!Str) 
00094     throw PGSTD::runtime_error("Attempt to convert NULL C string to C++ string");
00095   Obj = Str;
00096 }
00097 
00098 
00099 template<> inline void FromString(const char Str[], const char *&Obj)
00100 {
00101   if (!Str)
00102     throw PGSTD::runtime_error("Attempt to read NULL string");
00103   Obj = Str;
00104 }
00105 
00106 template<> inline void FromString(const char Str[], bool &Obj)
00107 {
00108   if (!Str)
00109     throw PGSTD::runtime_error("Attempt to read NULL string");
00110 
00111   switch (Str[0])
00112   {
00113   case 0:
00114   case 'f':
00115     Obj = false;
00116     break;
00117   case '0':
00118     {
00119       int I;
00120       FromString(Str, I);
00121       Obj = (I != 0);
00122     }
00123     break;
00124   default:
00125     Obj = true;
00126   }
00127 }
00128 
00129 
00132 template<typename T> PGSTD::string Quote(const T &Obj, bool EmptyIsNull=false);
00133 
00134 
00136 template<> inline PGSTD::string Quote(const PGSTD::string &Obj, 
00137                                       bool EmptyIsNull)
00138 {
00139     if (EmptyIsNull && Obj.empty())
00140         return "null";
00141 
00142     PGSTD::string Result = "'" + Obj;
00143     const char Special[] = "'\\";
00144     for (PGSTD::string::size_type i = Result.find_last_of(Special);
00145          i > 0;
00146          i = Result.find_last_of(Special, i))
00147       Result.insert(i, 1, Result[i]);
00148 
00149     return Result + "'";
00150 }
00151 
00152 
00155 template<> inline PGSTD::string Quote(const char *const & Obj, 
00156                                       bool EmptyIsNull)
00157 {
00158   if (!Obj) return "null";
00159   return Quote(PGSTD::string(Obj), EmptyIsNull);
00160 }
00161 
00162 
00166 template<typename T> inline PGSTD::string Quote(const T &Obj, bool EmptyIsNull)
00167 {
00168   return Quote(ToString(Obj), EmptyIsNull);
00169 }
00170 
00171 
00172 
00174 template<typename T> PGSTD::string Classname(const T *);
00175 
00176 
00182 template<typename GUEST>
00183 class Unique
00184 {
00185 public:
00186   Unique() : m_Guest(0) {}
00187 
00188   const GUEST *get() const throw () { return m_Guest; }
00189 
00190   void Register(const GUEST *G)
00191   {
00192     if (!G) throw PGSTD::logic_error("Internal libpqxx error: NULL " + 
00193                                      Classname(G));
00194     
00195     if (m_Guest)
00196     {
00197       if (G == m_Guest)
00198         throw PGSTD::logic_error(Classname(G) +
00199                                  " '" +
00200                                  G->Name() +
00201                                  "' started more than once without closing");
00202 
00203       throw PGSTD::logic_error("Started " + 
00204                                Classname(G) +
00205                                " '" + 
00206                                G->Name() + 
00207                                "' while '" +
00208                                m_Guest->Name() +
00209                                "' was still active");
00210     }
00211     
00212     m_Guest = G;
00213   }
00214 
00215   void Unregister(const GUEST *G)
00216   {
00217     if (G != m_Guest)
00218     {
00219       if (!G) 
00220         throw PGSTD::logic_error("Closing NULL " + Classname(G));
00221       else if (!m_Guest)
00222         throw PGSTD::logic_error("Closing " + 
00223                                  Classname(G) +
00224                                  " '" +
00225                                  G->Name() +
00226                                  "' which wasn't open");
00227       else
00228         throw PGSTD::logic_error("Closing wrong " + 
00229                                  Classname(G) +
00230                                  "; expected '" +
00231                                  m_Guest->Name() +
00232                                  "' but got '" +
00233                                  G->Name() +
00234                                  "'");
00235     }
00236 
00237     m_Guest = 0;
00238   }
00239 
00240 private:
00241   const GUEST *m_Guest;
00242 
00243   // Not allowed:
00244   Unique(const Unique &);
00245   Unique &operator=(const Unique &);
00246 };
00247 
00248 
00249 const Result_size_type Result_size_type_min =
00250   PGSTD::numeric_limits<Result_size_type>::min();
00251 const Result_size_type Result_size_type_max =
00252   PGSTD::numeric_limits<Result_size_type>::max();
00253 
00254 }
00255 
00256 #endif
00257 

Generated on Sun Dec 1 20:39:57 2002 for libpqxx by doxygen1.3-rc1