#ifndef ALIRSNEXPRESSION_H
#define ALIRSNEXPRESSION_H

#include <TObject.h>
#include <TString.h>

#include "AliRsnCutSet.h"

class TObjArray;
class AliRsnCutSet;
/**
  @author Martin Vala <Martin.Vala@cern.ch>
 */

// These are the valid operators types.

class AliRsnExpression : public TObject
{

  public:
  
  // operators for complex cut expressions
    enum ECutOp
    {
        kOpAND=1,   // AND '&'
        kOpOR,      // OR '|'
        kOpNOT      // Unary negation '!'
    };
  
    AliRsnExpression() : fVname ( 0 ), fArg1 ( 0 ), fArg2 ( 0 ), fOperator ( 0 )  {}
    AliRsnExpression ( TString exp );
    virtual    ~AliRsnExpression();
    AliRsnExpression ( const AliRsnExpression& exp );
    AliRsnExpression&    operator= ( const AliRsnExpression& exp );

    virtual Bool_t     Value ( TObjArray & vars );
    virtual TString     Unparse() const;

    void SetCutSet ( AliRsnCutSet* theValue ) { sCutSet = theValue; }
    AliRsnCutSet* GetCutSet() const { return sCutSet; }


    TString    fVname;   // Variable name
    static AliRsnCutSet        *sCutSet;

  private:
    AliRsnExpression*   fArg1;         // left argument
    AliRsnExpression*   fArg2;         // right argument
    Int_t                 fOperator;     // operator

    AliRsnExpression ( int op, AliRsnExpression* a );
    AliRsnExpression ( int op, AliRsnExpression* a, AliRsnExpression* b );

    TObjArray*    Tokenize ( TString str ) const;
    static AliRsnExpression*    Element ( TObjArray &st, Int_t &i );
    static AliRsnExpression*    Primary ( TObjArray &st, Int_t &i );
    static AliRsnExpression*    Expression ( TObjArray &st, Int_t &i );

    ClassDef ( AliRsnExpression, 1 ); // Class to evaluate an expression
};


///////////////////////////////////////////////////////////////////////////

class AliRsnVariableExpression: public AliRsnExpression
{
  public:
    AliRsnVariableExpression ( TString a) : AliRsnExpression() { fVname = a;  };
    ~AliRsnVariableExpression() {}
    virtual Bool_t    Value ( TObjArray& pgm );
    virtual TString    Unparse() const { return fVname; }

    ClassDef ( AliRsnVariableExpression, 1 ); // Class to define a variable expression
};

#endif