/*****************************************************************************
 * var_bool.hpp
 *****************************************************************************
 * Copyright (C) 2003 the VideoLAN team
 * $Id$
 *
 * Authors: Cyril Deguet     <asmax@via.ecp.fr>
 *          Olivier Teulière <ipkiss@via.ecp.fr>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

#ifndef VAR_BOOL_HPP
#define VAR_BOOL_HPP

#include "variable.hpp"
#include "observer.hpp"


/// Interface for read-only boolean variable
class VarBool: public Variable, public Subject<VarBool>
{
    public:
        /// Get the variable type
        virtual const string &getType() const { return m_type; }

        /// Get the boolean value
        virtual bool get() const = 0;

    protected:
        VarBool( intf_thread_t *pIntf ): Variable( pIntf ) {}
        virtual ~VarBool() {}

    private:
        /// Variable type
        static const string m_type;
};


/// Constant true VarBool
class VarBoolTrue: public VarBool
{
    public:
        VarBoolTrue( intf_thread_t *pIntf ): VarBool( pIntf ) {}
        virtual ~VarBoolTrue() {}
        virtual bool get() const { return true; }
};


/// Constant false VarBool
class VarBoolFalse: public VarBool
{
    public:
        VarBoolFalse( intf_thread_t *pIntf ): VarBool( pIntf ) {}
        virtual ~VarBoolFalse() {}
        virtual bool get() const { return false; }
};


/// Boolean variable implementation (read/write)
class VarBoolImpl: public VarBool
{
    public:
        VarBoolImpl( intf_thread_t *pIntf );
        virtual ~VarBoolImpl() {}

        // Get the boolean value
        virtual bool get() const { return m_value; }

        /// Set the internal value
        virtual void set( bool value );

    private:
        /// Boolean value
        bool m_value;
};


/// Conjunction of two boolean variables (AND)
class VarBoolAndBool: public VarBool, public Observer<VarBool>
{
    public:
        VarBoolAndBool( intf_thread_t *pIntf, VarBool &rVar1, VarBool &rVar2 );
        virtual ~VarBoolAndBool();

        // Get the boolean value
        virtual bool get() const { return m_rVar1.get() && m_rVar2.get(); }

        // Called when one of the observed variables is changed
        void onUpdate( Subject<VarBool> &rVariable );

    private:
        /// Boolean variables
        VarBool &m_rVar1, &m_rVar2;
};


/// Disjunction of two boolean variables (OR)
class VarBoolOrBool: public VarBool, public Observer<VarBool>
{
    public:
        VarBoolOrBool( intf_thread_t *pIntf, VarBool &rVar1, VarBool &rVar2 );
        virtual ~VarBoolOrBool();

        // Get the boolean value
        virtual bool get() const { return m_rVar1.get() || m_rVar2.get(); }

        // Called when one of the observed variables is changed
        void onUpdate( Subject<VarBool> &rVariable );

    private:
        /// Boolean variables
        VarBool &m_rVar1, &m_rVar2;
};


/// Negation of a boolean variable (NOT)
class VarNotBool: public VarBool, public Observer<VarBool>
{
    public:
        VarNotBool( intf_thread_t *pIntf, VarBool &rVar );
        virtual ~VarNotBool();

        // Get the boolean value
        virtual bool get() const { return !m_rVar.get(); }

        // Called when the observed variable is changed
        void onUpdate( Subject<VarBool> &rVariable );

    private:
        /// Boolean variable
        VarBool &m_rVar;
};


#endif
