Drizzled Public API Documentation

result_set.h
00001 /* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
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00004  * Copyright (C) 2011, Brian Aker
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00006  *
00007  * Redistribution and use in source and binary forms, with or without
00008  * modification, are permitted provided that the following conditions are met:
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00031 
00032 #pragma once
00033 
00034 #include <drizzled/visibility.h>
00035 #include <drizzled/sql/exception.h>
00036 #include <drizzled/sql/result_set_meta_data.h>
00037 #include <cassert>
00038 #include <queue>
00039 
00040 namespace drizzled {
00041 
00042 namespace plugin { class Client; }
00043 
00044 namespace sql {
00045 
00046 class DRIZZLED_API ResultSet
00047 {
00048   // First version of API stores everything as strings
00049   class Column {
00050   public:
00051     Column() :
00052       _is_null(false)
00053     { }
00054 
00055     inline const std::string &value() const
00056     {
00057       return _value;
00058     }
00059 
00060     inline bool isNull() const
00061     {
00062       return _is_null;
00063     }
00064 
00065     inline void set_value(const std::string &ref)
00066     {
00067       _value= ref;
00068     }
00069 
00070     inline void set_null()
00071     {
00072       assert(_value.empty());
00073       _is_null= true;
00074     }
00075 
00076   private:
00077     std::string _value;
00078     bool _is_null;
00079   };
00080 
00081   typedef std::vector< Column > Row;
00082   typedef std::vector< Row > Result;
00083 
00084 public:
00085   static ResultSet *make(size_t field_count)
00086   {
00087     return new ResultSet(field_count);
00088   }
00089 
00090   // Special case for us (throw is just too damn slow for internal usage, or
00091   // almost any).
00092   bool isNoThrow() const
00093   {
00094     return true;
00095   }
00096 
00097   bool next() const;
00098 
00099   const std::string getString(size_t column_number) const ;
00100   bool isNull(size_t column_number) const;
00101   const ResultSetMetaData &getMetaData() const;
00102 
00103   // Our functions to use instead of exceptions
00104   bool error() const;
00105   sql::Exception getException() const;
00106 
00107 #if 0
00108 protected:
00109   friend class Client;
00110 #endif
00111   ResultSet(size_t fields) :
00112     _has_next_been_called(false),
00113     _current_row(_results.end()),
00114     _meta_data(fields)
00115   {
00116   }
00117 
00118   ~ResultSet();
00119 
00120   void createRow();
00121   void setColumn(size_t column_number, const std::string &arg);
00122   void setColumnNull(size_t column_number);
00123   void pushException(const Exception &arg) const;
00124 
00125 private: // Member methods
00126   bool isMore() const;
00127   bool isMore(size_t column_number) const;
00128 
00129 private: // Member variables
00130   mutable bool _has_next_been_called;
00131   Result _results;
00132   mutable Result::const_iterator _current_row;
00133   ResultSetMetaData _meta_data;
00134   
00135   // Because an error could come up during a fetch on const, we need to have
00136   // this be mutable.
00137   mutable std::queue<Exception> _exceptions;
00138 };
00139 
00140 std::ostream& operator<<(std::ostream& output, const ResultSet &result_set);
00141 
00142 } // namespace sql 
00143 } // namespace drizzled
00144