#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