JDBReader.hh

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#ifndef __JDB_JDBREADER__
#define __JDB_JDBREADER__

#include <string>
#include <vector>

#include "dbclient/KM3NeTDBClient.h"

#include "JLang/JNullStream.hh"
#include "JLang/JEquationParameters.hh"
#include "JLang/JRedirectString.hh"
#include "JLang/JSingleton.hh"
#include "JLang/JLangToolkit.hh"
#include "JROOT/JRootClass.hh"
#include "JROOT/JRootDictionary.hh"
#include "JROOT/JRootStreamer.hh"

#include "JDB/JDBDictionary.hh"


/**
 * \author mdejong
 */
namespace JDATABASE {}
namespace JPP { using namespace JDATABASE; }

namespace JDATABASE {

  using JLANG::JSingleton;
  using KM3NeT::DB::ResultSet;
  using KM3NeT::DB::Selector;
  using JROOT::JRootReader;


  /**
   * Special characters.
   */
  static const std::string SPECIAL_CHARACTERS  =  "!@#$%^&*()-+=[]{};:'\"\\|,.<>/?";


  /**
   * Read object with ROOT dictionary from selector.
   *
   * \param  selection     selection
   * \param  object        object
   * \return               true if read; else false
   */
  template<class T>
  inline bool operator>>(const std::vector<Selector>& selection, T& object)
  {
    using namespace std;
    using namespace JPP;

    JRootReader        reader(null, JEquationParameters(), JDBDictionary::getInstance());

    JRootReadableClass cls(object);

    for (vector<Selector>::const_iterator i = selection.begin(); i != selection.end(); ++i) {

      string parameter = to_upper(i->Name);

      for (string::const_iterator i = SPECIAL_CHARACTERS.begin(); i != SPECIAL_CHARACTERS.end(); ++i) {
        for (string::size_type pos; (pos = parameter.find(*i)) != string::npos; ) {
          parameter.erase(pos);
        }
      }
     
      JRootReadableClass abc = cls.find(parameter.c_str());
    
      if (abc.is_valid()) {     

        JRedirectString redirect(reader, i->Value);
      
        reader.getObject(abc);
      }
    }

    return true;
  }


  /**
   * Auxiliary class to read object with ROOT dictionary from database.
   *
   * The names of the table columns are one-to-one mapped to the names of the data members 
   * of the corresponding data structure using the corresponding ROOT dictionary.\n 
   * For this, all special characters (JDATABASE::SPECIAL_CHARACTERS) are removed from the column names.\n
   * The static method JDBReader::set can be used to <em>a priori</em> assign default values 
   * to those data members that are defined by the selector used in the query.\n
   * Note that the list of column names associated to the template parameter is considered to be permanent.\n
   * If not, the static method JDBReader::reset should be called before the next read operation.
   */
  template<class T>
  struct JDBReader :
    public JRootReader,
    public JSingleton< JDBReader<T> >
  {
    /**
     * Default constructor.
     */
    JDBReader() :
      JRootReader(JLANG::null, JLANG::JEquationParameters(), JDBDictionary::getInstance())
    {}


    /**
     * Reset internal lookup table and default value.
     */
    static void reset()
    {
      JDBReader<T>::getInstance().columns.clear();

      JDBReader<T>::getInstance().value = T();
    }


    /**
     * Set default value corresponding to given selection.
     *
     * \param  selection     selection
     */
    static void set(const std::vector<Selector>& selection)
    {
      selection >> JDBReader<T>::getInstance().value;
    }


    /**
     * Read object with ROOT dictionary from result set.
     *
     * \param  rs            result set
     * \return               object
     */
    const T& operator()(ResultSet& rs) 
    {
      using namespace std;
      using namespace JPP;

      object = value;

      if (columns.empty()) {

        JRootReadableClass cls(object);

        for (size_t i = 0; i != rs.FieldCount(); ++i) {

          string parameter = rs.FieldName(i);

          for (string::const_iterator i = SPECIAL_CHARACTERS.begin(); i != SPECIAL_CHARACTERS.end(); ++i) {
            for (string::size_type pos; (pos = parameter.find(*i)) != string::npos; ) {
              parameter.erase(pos);
            }
          }
        
          columns.push_back(cls.find(parameter.c_str()));
        }
      }

      for (unsigned int i = 0; i != rs.FieldCount(); ++i) {

        if (columns[i].is_valid()) {     

          JRedirectString redirect(*this, rs.GetString(i));
      
          this->getObject(columns[i]);
        }
      }

      return object;
    }

  private:
    T  object;                                      //!< internal value
    T  value;                                       //!< default  value

    std::vector<JROOT::JRootReadableClass> columns; //!< field count -> data member
  };


  /**
   * Read object with ROOT dictionary from result set.
   *
   * \param  rs            result set
   * \param  object        object
   * \return               true if read; else false
   */
  template<class T>
  inline bool operator>>(ResultSet& rs, T& object)
  {
    JDBReader<T>& reader = JDBReader<T>::getInstance();

    if (rs.Next()) {

      object = reader(rs);

      return true;
    }

    return false;
  }


  /**
   * Read multiple objects with ROOT dictionary from result set.
   *
   * \param  rs            result set
   * \param  buffer        container of objects with ROOT dictionary
   * \return               true if read; else false
   */
  template<class JElement_t, class JAllocator_t>
  inline bool operator>>(ResultSet& rs, std::vector<JElement_t, JAllocator_t>& buffer)
  {
    for (JElement_t object; rs >> object; ) {
      buffer.push_back(object);
    }

    return true;
  }
}

#endif