variant.h

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/*
    Copyright (C) 2014 Paul Davis
    Author: David Robillard

    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 __ardour_variant_h__
#define __ardour_variant_h__

#include <stdint.h>
#include <limits.h>

#include <algorithm>
#include <stdexcept>

#include "ardour/libardour_visibility.h"
#include "evoral/types.hpp"
#include "pbd/compose.h"

namespace ARDOUR {

class LIBARDOUR_API Variant
{
public:
        enum Type {
                NOTHING, 
                BEATS,   
                BOOL,    
                DOUBLE,  
                FLOAT,   
                INT,     
                LONG,    
                PATH,    
                STRING,  
                URI      
        };

        Variant() : _type(NOTHING) { _long = 0; }

        explicit Variant(bool    value) : _type(BOOL)    { _bool   = value; }
        explicit Variant(double  value) : _type(DOUBLE)  { _double = value; }
        explicit Variant(float   value) : _type(FLOAT)   { _float  = value; }
        explicit Variant(int32_t value) : _type(INT)     { _int    = value; }
        explicit Variant(int64_t value) : _type(LONG)    { _long   = value; }

        explicit Variant(const Evoral::Beats& beats)
                : _type(BEATS)
                , _beats(beats)
        {}

        Variant(Type type, const std::string& value)
                : _type(type)
                , _string(value)
        {}

        Variant(Type type, double value)
                : _type(type)
        {
                switch (type) {
                case BOOL:
                        _bool = value != 0.0;
                        break;
                case DOUBLE:
                        _double = (double)value;
                        break;
                case FLOAT:
                        _float = (float)value;
                        break;
                case INT:
                        _int = (int32_t)lrint(std::max((double)INT32_MIN,
                                                       std::min(value, (double)INT32_MAX)));
                        break;
                case LONG:
                        _long = (int64_t)lrint(std::max((double)INT64_MIN,
                                                        std::min(value, (double)INT64_MAX)));
                        break;
                case BEATS:
                        _beats = Evoral::Beats(value);
                        break;
                default:
                        _type = NOTHING;
                        _long = 0;
                }
        }

        double to_double() const {
                switch (_type) {
                case BOOL:   return _bool;
                case DOUBLE: return _double;
                case FLOAT:  return _float;
                case INT:    return _int;
                case LONG:   return _long;
                case BEATS:  return _beats.to_double();
                default:     return 0.0;
                }
        }

        bool   get_bool()   const { ensure_type(BOOL);   return _bool;   }
        double get_double() const { ensure_type(DOUBLE); return _double; }
        float  get_float()  const { ensure_type(FLOAT);  return _float;  }
        int    get_int()    const { ensure_type(INT);    return _int;    }
        long   get_long()   const { ensure_type(LONG);   return _long;   }

        bool   operator==(bool v)   const { return _type == BOOL   && _bool == v; }
        double operator==(double v) const { return _type == DOUBLE && _double == v; }
        float  operator==(float v)  const { return _type == FLOAT  && _float == v; }
        int    operator==(int v)    const { return _type == INT    && _int == v; }
        long   operator==(long v)   const { return _type == LONG   && _long == v; }

        Variant& operator=(bool v)   { _type = BOOL;   _bool = v;   return *this; }
        Variant& operator=(double v) { _type = DOUBLE; _double = v; return *this; }
        Variant& operator=(float v)  { _type = FLOAT;  _float = v;  return *this; }
        Variant& operator=(int v)    { _type = INT;    _int = v;    return *this; }
        Variant& operator=(long v)   { _type = LONG;   _long = v;   return *this; }

        const std::string& get_path()   const { ensure_type(PATH);   return _string; }
        const std::string& get_string() const { ensure_type(STRING); return _string; }
        const std::string& get_uri()    const { ensure_type(URI);    return _string; }

        bool operator==(const Variant& v) const {
                if (_type != v._type) {
                        return false;
                }

                switch (_type) {
                case NOTHING: return true;
                case BEATS:   return _beats  == v._beats;
                case BOOL:    return _bool   == v._bool;
                case DOUBLE:  return _double == v._double;
                case FLOAT:   return _float  == v._float;
                case INT:     return _int    == v._int;
                case LONG:    return _long   == v._long;
                case PATH:
                case STRING:
                case URI:     return _string == v._string;
                }

                return false;
        }

        bool operator==(const Evoral::Beats& v) const {
                return _type == BEATS && _beats == v;
        }

        bool operator!() const { return _type == NOTHING; }

        Variant& operator=(Evoral::Beats v) {
                _type  = BEATS;
                _beats = v;
                return *this;
        }

        const Evoral::Beats& get_beats() const {
                ensure_type(BEATS); return _beats;
        }

        Type type() const { return _type; }

        static bool type_is_numeric(Type type) {
                switch (type) {
                case BOOL: case DOUBLE: case FLOAT: case INT: case LONG: case BEATS:
                        return true;
                default:
                        return false;
                }
        }

private:
        static const char* type_name(const Type type) {
                static const char* names[] = {
                        "bool", "double", "float", "int", "long", "path", "string", "uri"
                };

                return names[type];
        }

        void ensure_type(const Type type) const {
                if (_type != type) {
                        throw std::domain_error(
                                string_compose("get_%1 called on %2 variant",
                                               type_name(type), type_name(_type)));
                }
        }

        Type          _type;    
        std::string   _string;  
        Evoral::Beats _beats;   

        // Union of all primitive numeric types
        union {
                bool    _bool;
                double  _double;
                float   _float;
                int32_t _int;
                int64_t _long;
        };
};

} // namespace ARDOUR

#endif // __ardour_variant_h__