configuration_variable.h

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/*
 * Copyright (C) 1999-2015 Paul Davis <paul@linuxaudiosystems.com>
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#ifndef __libpbd_configuration_variable_h__
#define __libpbd_configuration_variable_h__
 
#include <string>
 
#include "pbd/xml++.h"
#include "pbd/string_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&) const;
        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 {
                return to_string<T>(value);
        }
 
        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) {
                value = string_to<T>(s);
        }
 
  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 T>
class /*LIBPBD_API*/ ConfigVariableWithMutation : public ConfigVariable<T>
{
  public:
        ConfigVariableWithMutation (std::string name, T val, T (*m)(T))
                : ConfigVariable<T> (name, m (val)), unmutated_value (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) {
                set (string_to<T>(s));
        }
 
  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__ */