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// 
// --------------------------------------------------------------------
// GEANT 4 class header file
//
// G4coutDestination.hh
//
// --------------------------------------------------------------------
#ifndef G4COUTDESTINATION_HH
#define G4COUTDESTINATION_HH

#include <functional>
#include <vector>
#include <algorithm>
#include <iostream>

#include "globals.hh"

class G4coutDestination
{
  public:

    G4coutDestination() = default;
    virtual ~G4coutDestination();
    // Note: limitation on ICC for MIC cannot use 'default';

    // The type of the functions defining a transformation of the message.
    // The function manipulates the input message, for example, to add a prefix:
    //    G4coutDestination::AddCoutTransformer(
    //       [](G4String& msg) -> G4bool { msg="PREFIX "+msg; return true; }
    //    );
    // Function should return false if message should not be processed
    // anymore and discarded
    //
    using Transformer=std::function<G4bool(G4String&)>;
    void AddCoutTransformer(const Transformer& t)
      { transformersCout.push_back(t); }
    void AddCoutTransformer( Transformer&& t)
      { transformersCout.push_back(t); }
    void AddCerrTransformer(const Transformer& t)
      { transformersCerr.push_back(t); }
    void AddCerrTransformer( Transformer&& t)
      { transformersCerr.push_back(t); }
    virtual void ResetTransformers();

    // Derived class implements here handling of message.
    // For example, streaming on std::cout or file.
    // Return 0 for success, -1 otherwise
    //
    virtual G4int ReceiveG4cout(const G4String& msg);
    virtual G4int ReceiveG4cerr(const G4String& msg);

    // Methods called by G4strbuf when need to handle a message
    //
    G4int ReceiveG4cout_(const G4String& msg);

    // Transformers cannot remove an error message from stream
    //
    G4int ReceiveG4cerr_(const G4String& msg);

  protected:

    // For MT: if master G4coutDestination derived
    // class wants to intercept the thread outputs
    // derived class should set this pointer.
    // Needed for some G4UIsession like GUIs
    //
    static G4coutDestination* masterG4coutDestination;

    std::vector<Transformer> transformersCout;
    std::vector<Transformer> transformersCerr;
};

#endif
