EmdrosEnv

Overview

The EmdrosEnv class is an abstraction of the Emdros API. Use it in your applications as the main interface to Emdros.

C++ interface

#include <emdros_environment.h>

/** Backend kind
 *
 * Used to distinguish among backends.
 *
 */
enum eBackendKind {
	kBackendNone = 0,/**< No backend selected */
	kPostgreSQL = 1, /**< PostgreSQL */
	kMySQL = 2,      /**< MySQL */
	kSQLite2 = 3,    /**< SQLite 2.X.X */
	kSQLite3 = 4     /**< SQLite 3.X.X */
};



class EmdrosEnv {
public:
  EmdrosEnv(std::ostream* output_stream, 
             eOutputKind output_kind, eCharsets charset, 
             std::string hostname, 
             std::string user, std::string password, 
             std::string initial_db,
             eBackendKind backend_kind = DEFAULT_BACKEND_ENUM);
  // The following constructor uses std::cout (Standard Out)
  EmdrosEnv(eOutputKind output_kind, eCharsets charset, 
             std::string hostname, 
             std::string user, std::string password, 
             std::string initial_db,
             eBackendKind backend_kind = DEFAULT_BACKEND_ENUM);
  virtual ~EmdrosEnv();

  // Backend-name
  static std::string getBackendName(void);


  // Executing MQL queries
  // See the mqlExecute* functions
  // for information on the parameters.
  bool executeString(const std::string& input, bool& bResult, 
                      bool bPrintResult, bool bReportError);
  bool executeFile(std::string filename, bool& bResult, 
                    bool bPrintResult, bool bReportError);
  bool executeStream(std::istream& strin, bool& bResult, 
                      bool bPrintResult, bool bReportError);

  // Cleaning up
  // clean() calls MQLExecEnv::clean().
  // It is good to call if you are through with a query's results
  // and there is a long time till the next executeXXX call.
  void clean();

  // Database support
  // Call the corresponding EMdFDB methods
  bool connectionOk(void);
  bool vacuum(bool bAnalyze);
  bool getMin_m(monad_m& /* out */ min_m);
  bool getMax_m(monad_m& /* out */ max_m);
  bool getAll_m_1(SetOfMonads& /* out */ all_m_1);

  // Returns the string-representation of an enumeration constant in 
  // enum enum_name with the value value.
  // Just calls the corresponding EMdFDB method.
  // bDBOK is true on no DB error.
  virtual std::string getEnumConstNameFromValue(long value,
                                                const std::string& enum_name,
                                                /* out */ bool &bDBOK);


  // Transactions
  // Call the corresponding EMdFDB methods
  bool beginTransaction(void);
  bool commitTransaction(void);
  bool abortTransaction(void);

  //
  // Check for results
  //

  // Check for sheaf
  // Returns true on result is sheaf.  
  // Returns false on no result or result not sheaf 
  bool isSheaf(void); 

  // Check for table
  // Returns true on result is table.
  // Returns false on no result or result not table.
  bool isTable(void); 

  // NOTE on statements:
  // If only one MQL query was executed by the last executeXXX
  // invocation, then there will be only one statement to get.  
  // If more than one MQL query was given to one of these methods,
  // only the results from the last statement executed will be available.

  // Getting results.  Next invocation of executeXXX deletes the object,
  // so you cannot execute a query until you are done processing
  // the result
  MQLResult* getResult(void); // Return nil on no result
  Sheaf* getSheaf(void); // Returns nil on no result or result not a sheaf
  FlatSheaf* getFlatSheaf(void); // Returns nil on no result or result not a flat sheaf
  Table* getTable(void); // Returns nil on no result or result not a table
  Statement *getStatement(void); // Returns nil on no statement

  // Take over object.  You now have responsibility for deleting it, 
  // and it will not be deleted by the next invocation of executeXXX.
  MQLResult* takeOverResult(void); // Return nil on no result
  Sheaf* takeOverSheaf(void); // Returns nil on no result or result not a sheaf
  FlatSheaf* takeOverFlatSheaf(void); // Returns nil on no result or result not a flat sheaf
  Table* takeOverTable(void); // Returns nil on no result or result not a table
  Statement *takeOverStatement(void); // Returns nil on no statement



  // Getting error-messages and info
  std::string getDBError(void);
  std::string getCompilerError(void);
  // Gets the compiler stage that was executed last
  int getLastCompilerStage(void); 
  // clears local DB error message in EMdFDB and local error in MQLError
  void clearErrors(void); 

  // Outputting
  // These all output on the stream in local EMdFOutput,
  // i.e., the stream you passed to the constructor of EmdrosEnv,
  // or stdout if the other constructor was used
  void out(std::string str);  // out your own string
  void out(MQLResult *pResult);
  void out(Sheaf *pSheaf);
  void out(Table *pTable);

  //
  // XML outputting
  //

  // XML declaration.
  // Calls EMdFOutput::printXMLDecl on the local EMdFOutput
  void printXMLDecl(); 

  // DTDs
  void printDTDStart(std::string root_element);
  void printDTDEnd();
  void printDTDMQLResult(void);
  void printDTDTable(void);
  void printDTDSheaf(void);

  // Accessing members
  MQLExecEnv* getMQLEE(void);
};