MQwHistograms.h

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/*!
 * \file   MQwHistograms.h
 * \brief  Mix-in class for histogram management functionality
 */
 
#pragma once
 
// System headers
#include <vector>
 
// Root headers
#include "TH1.h"
 
// Qweak headers
#include "QwLog.h"
 
/**
 * \class MQwHistograms
 * \ingroup QwAnalysis
 * \brief Mix-in class providing histogram management functionality
 *
 * Provides a common interface for data elements that need to create
 * and fill ROOT histograms. Manages histogram pointers and provides
 * utilities for histogram registration and sharing between objects.
 */
class MQwHistograms {
 
    /// Regular pointers for the histograms
    typedef TH1* TH1_ptr;
    // Shared pointers (std::shared_ptr) are not advisable
    // because ROOT keep ownership of all histograms.  They
    // are automatically deleted when ROOT closes the file.
    // If we put them in a shared_ptr here, they would be
    // deleted by the time the shared_ptr goes out of scope.
 
  protected:
    /// Default constructor
    MQwHistograms() { }
    /// Copy constructor
    MQwHistograms(const MQwHistograms& source)
    : fHistograms(source.fHistograms) { }
    /// Virtual destructor
    virtual ~MQwHistograms() { }
 
    /// Arithmetic assignment operator:  Should only copy event-based data.
    /// In this particular class, there is no event-based data.
    MQwHistograms& operator=(const MQwHistograms& value) {
      if (this != &value) {
        // No event-based data to copy in this class
      }
      return *this;
    }
 
    inline void Fill_Pointer(TH1_ptr hist_ptr, Double_t value){
      if (hist_ptr != nullptr){
        hist_ptr->Fill(value);
      }
    }
 
  protected:
    /// Histograms associated with this data element
    std::vector<TH1_ptr> fHistograms;
 
  protected:
    /// Register a histogram
    void AddHistogram(TH1* h) {
      fHistograms.push_back(TH1_ptr(h));
      fHistograms.back()->SetBuffer(1000);
    }
 
  public:
    /// Share histogram pointers between objects
    void ShareHistograms(const MQwHistograms* source) {
      if (source) fHistograms = source->fHistograms;
    }
 
}; // class MQwHistograms