configuration_variable.h

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/*
    Copyright (C) 2000-2007 Paul Davis

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#ifndef __libpbd_configuration_variable_h__
#define __libpbd_configuration_variable_h__

#include <iostream>
#include <sstream>
#include <string>

#include "pbd/xml++.h"
#include "pbd/convert.h"
#include "pbd/libpbd_visibility.h"

namespace PBD {

class LIBPBD_API ConfigVariableBase {
  public:

        ConfigVariableBase (std::string str) : _name (str) {}
        virtual ~ConfigVariableBase() {}

        std::string name () const { return _name; }
        void add_to_node (XMLNode&);
        bool set_from_node (XMLNode const &);

        virtual std::string get_as_string () const = 0;
        virtual void set_from_string (std::string const &) = 0;

  protected:
        std::string _name;

        void notify ();
        void miss ();
};

template<class T>
class /*LIBPBD_API*/ ConfigVariable : public ConfigVariableBase
{
  public:

        ConfigVariable (std::string str) : ConfigVariableBase (str) {}
        ConfigVariable (std::string str, T val) : ConfigVariableBase (str), value (val) {}

        T get() const {
                return value;
        }

        std::string get_as_string () const {
                std::ostringstream ss;
                ss << value;
                return ss.str ();
        }

        virtual bool set (T val) {
                if (val == value) {
                        miss ();
                        return false;
                }
                value = val;
                notify ();
                return true;
        }

        virtual void set_from_string (std::string const & s) {
                std::stringstream ss;
                ss << s;
                ss >> value;
        }

  protected:
        virtual T get_for_save() { return value; }
        T value;
};

template<>
class /*LIBPBD_API*/ ConfigVariable<std::string> : public ConfigVariableBase
{
  public:

        ConfigVariable (std::string str) : ConfigVariableBase (str) {}
        ConfigVariable (std::string str, std::string val) : ConfigVariableBase (str), value (val) {}

        std::string get() const {
                return value;
        }

        std::string get_as_string () const {
                return value;
        }

        virtual bool set (std::string val) {
                if (val == value) {
                        miss ();
                        return false;
                }
                value = val;
                notify ();
                return true;
        }

        virtual void set_from_string (std::string const & s) {
                value = s;
        }

  protected:
        virtual std::string get_for_save() { return value; }
        std::string value;
};

template<>
class /*LIBPBD_API*/ ConfigVariable<bool> : public ConfigVariableBase
{
  public:

        ConfigVariable (std::string str) : ConfigVariableBase (str), value (false) {}
        ConfigVariable (std::string str, bool val) : ConfigVariableBase (str), value (val) {}

        bool get() const {
                return value;
        }

        std::string get_as_string () const {
                std::ostringstream ss;
                ss << value;
                return ss.str ();
        }

        virtual bool set (bool val) {
                if (val == value) {
                        miss ();
                        return false;
                }
                value = val;
                notify ();
                return true;
        }

        void set_from_string (std::string const & s) {
                value = PBD::string_is_affirmative (s);
        }

  protected:
        virtual bool get_for_save() { return value; }
        bool value;
};

template<class T>
class /*LIBPBD_API*/ ConfigVariableWithMutation : public ConfigVariable<T>
{
  public:
        ConfigVariableWithMutation (std::string name, T val, T (*m)(T))
                : ConfigVariable<T> (name, val), mutator (m) {}

        bool set (T val) {
                if (unmutated_value != val) {
                        unmutated_value = val;
                        return ConfigVariable<T>::set (mutator (val));
                }
                return false;
        }

        void set_from_string (std::string const & s) {
                T v;
                std::stringstream ss;
                ss << s;
                ss >> v;
                set (v);
        }

  protected:
        virtual T get_for_save() { return unmutated_value; }
        T unmutated_value;
        T (*mutator)(T);
};

template<>
class /*LIBPBD_API*/ ConfigVariableWithMutation<std::string> : public ConfigVariable<std::string>
{
  public:
        ConfigVariableWithMutation (std::string name, std::string val, std::string (*m)(std::string))
                : ConfigVariable<std::string> (name, val), mutator (m) {}

        bool set (std::string val) {
                if (unmutated_value != val) {
                        unmutated_value = val;
                        return ConfigVariable<std::string>::set (mutator (val));
                }
                return false;
        }

        void set_from_string (std::string const & s) {
                set (s);
        }

  protected:
        virtual std::string get_for_save() { return unmutated_value; }
        std::string unmutated_value;
        std::string (*mutator)(std::string);
};

}

#endif /* __libpbd_configuration_variable_h__ */