JRootFileReader.hh

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#ifndef __JROOTFILEREADER__
#define __JROOTFILEREADER__

#include <string>
#include <limits>

#include "TFile.h"
#include "TString.h"

#include "JLang/JObjectIterator.hh"
#include "JLang/JException.hh"
#include "JLang/JType.hh"
#include "JROOT/JTreeReaderObjectIterator.hh"
#include "JROOT/JTreeParameters.hh"
#include "JROOT/JRootFile.hh"
#include "JROOT/JRootSupportkit.hh"


/**
 * \author mdejong
 */

namespace JROOT {}
namespace JPP { using namespace JROOT; }

namespace JROOT {
  
  using JLANG::JAccessibleObjectIterator;
  using JLANG::JRewindableObjectIterator;
  using JLANG::JType;
  using JLANG::skip_type;


  /**
   * Read object from ROOT file.
   *
   * \param  file       pointer to file
   * \param  key        key of object to be read
   * \param  ps         pointer to object
   */
  template<class T>
  inline void getObject(TFile* file, const TString& key, T*& ps)
  {
    if (file != NULL) {
      file->GetObject(key, ps);
    }
  }


  /**
   * ROOT file reader.
   */
  template<class T, bool = JTreeParametersAvailable<T>::result>
  class JRootFileReader;


  /**
   * Tempate specialisation of JRootFileReader for TTree incompatible iteration.
   *
   * The methods JROOT::actionAtFileOpen and JROOT::actionAtFileRead are called
   * at opening of each file and reading of each object, respectively. 
   *
   * This class implements the JLANG::JAccessibleObjectIterator interface.
   */
  template<class T>
  class JRootFileReader<T,false> :
    public JAccessibleObjectIterator<T>,
    public JRewindableObjectIterator<T>,
    public JRootInputFile
  {
  public:

    typedef typename JAccessibleObjectIterator<T>::pointer_type  pointer_type;

    
    /**
     * Default constructor.
     */
    JRootFileReader() :
      cycleOld(0),
      cycleNew(1),
      __p (NULL),
      name(getName(JType<T>()))
    {}


    /**
     * Constructor.
     *
     * \param  file_name  file name
     * \param  key        key of object to be read
     */
    JRootFileReader(const char* file_name,
                    const char* key = getName(JType<T>())) :
      cycleOld(0),
      cycleNew(1),
      __p (NULL),
      name(key)
    {
      open(file_name);
    }


    /**
     * Rewind.
     */
    virtual void rewind() override 
    {
      cycleOld = 0;
      cycleNew = 1;
    }


    /**
     * Open file.
     *
     * \param  file_name      file name
     */
    virtual void open(const char* file_name) override 
    {
      JRootInputFile::open(file_name);

      actionAtFileOpen<T>(this->getFile());
      
      rewind();
    }
    

    /**
     * Check availability of next element.
     *
     * \return            true if the iteration has more elements; else false
     */
    virtual bool hasNext() override 
    {
      if (is_open()) {

        if (cycleOld != cycleNew) {
          
          TString key(name);
          
          key += ';';
          key += cycleNew;
        
          cycleOld = cycleNew;
          __p      = NULL;
          
          getObject(getFile(), key, __p);

          actionAtFileRead<T>(__p);
        }
        
        return (cycleOld == cycleNew && __p != NULL);
      }

      return false;
    }


    /**
     * Get next element.
     *
     * \return            pointer to element.
     */
    virtual const pointer_type& next() override 
    {
      static pointer_type ps;
      
      if (hasNext()) {

        ++cycleNew;

        ps.reset(__p);

      } else {

        ps.reset(NULL);
      }

      return ps;
    }


    /**
     * Skip items.
     *
     * \param  ns         number of items to skip
     * \return            number of items skipped
     */
    virtual skip_type skip(const skip_type ns) override 
    {
      using namespace std;

      if (ns < (skip_type) cycleNew + (skip_type) numeric_limits<Short_t>::max())
        cycleNew += (Short_t) ns;
      else
        cycleNew  = numeric_limits<Short_t>::max();

      return cycleNew - cycleOld;
    }
    

    /**
     * Get cycle number of last read object.
     *
     * \return            cycle number
     */
    Short_t getCycle() const
    {
      return cycleOld;
    }
    
  protected:
    Short_t cycleOld;
    Short_t cycleNew;
    T*      __p;
    TString name;
  };


  /**
   * Tempate specialisation of JRootFileReader for TTree compatible iteration.
   *
   * The method JROOT::actionAtFileOpen is called at opening of each file.
   *
   * This class implements the JLANG::JAccessibleObjectIterator interface.
   */
  template<class T>
  class JRootFileReader<T,true> : 
    public JTreeReaderAccessibleObjectIterator<T> 
  {
    /**
     * Open file.
     *
     * \param  file_name      file name
     */
    virtual void open(const char* file_name) override 
    {
      JTreeReaderAccessibleObjectIterator<T>::open(file_name);

      if (this->get() != NULL) {
        actionAtFileOpen<T>(this->get()->GetCurrentFile());
      }
    }
  };
}

#endif