kvp-value.hpp

/********************************************************************\
 * kvp-value.hpp -- Implements a key-value frame system             *
 * Copyright (C) 2014 Aaron Laws                                    *
 *                                                                  *
 * 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, contact:                        *
 *                                                                  *
 * Free Software Foundation           Voice:  +1-617-542-5942       *
 * 51 Franklin Street, Fifth Floor    Fax:    +1-617-542-2652       *
 * Boston, MA  02110-1301,  USA       gnu@gnu.org                   *
 *                                                                  *
\********************************************************************/

#ifndef GNC_KVP_VALUE_TYPE
#define GNC_KVP_VALUE_TYPE

#include <config.h>
#include "qof.h"

#include <boost/variant.hpp>

//Must be a struct because it's exposed to C so that it can in turn be
//translated to/from Scheme.
struct KvpValueImpl
{
    public:
    enum Type
    {
        INVALID = -1,
        INT64 = 1, 
        DOUBLE,     
        NUMERIC,    
        STRING,     
        GUID,       
        TIME64,   
        PLACEHOLDER_DONT_USE, /* Replaces KVP_TYPE_BINARY */
        GLIST,      
        FRAME,      
        GDATE,      
    };

    KvpValueImpl(KvpValueImpl const &) noexcept;
    KvpValueImpl& operator=(const KvpValueImpl&) noexcept;

    KvpValueImpl(KvpValueImpl && b) noexcept;
    KvpValueImpl& operator=(KvpValueImpl && b) noexcept;

    template <typename T>
    KvpValueImpl(T) noexcept;

    ~KvpValueImpl() noexcept;

    KvpValueImpl * add (KvpValueImpl *) noexcept;

    KvpValueImpl::Type get_type() const noexcept;

    std::string to_string() const noexcept;
    std::string to_string(std::string const & prefix) const noexcept;

    template <typename T>
    T get() const noexcept;
    template <typename T>
    const T* get_ptr() const noexcept;

    template <typename T>
    void set(T) noexcept;

    friend int compare(const KvpValueImpl &, const KvpValueImpl &) noexcept;

    private:
    void duplicate(const KvpValueImpl&) noexcept;
    boost::variant<
        int64_t,
        double,
        gnc_numeric,
        const char*,
        GncGUID *,
        Time64,
        GList *,
        KvpFrame *,
        GDate> datastore;
};

int
compare(const KvpValueImpl *, const KvpValue *) noexcept;
template <typename T>
KvpValueImpl::KvpValueImpl(T newvalue) noexcept:
    datastore(newvalue)
{
}

template <typename T> T
KvpValueImpl::get() const noexcept
{
    if (this->datastore.type() != boost::typeindex::type_id<T>()) return {};
    return boost::get<T>(datastore);
}

template <typename T> const T*
KvpValueImpl::get_ptr() const noexcept
{
    if (this->datastore.type() != typeid(T)) return nullptr;
    return boost::get<T>(&datastore);
}

template <typename T> void
KvpValueImpl::set(T val) noexcept
{
    this->datastore = val;
}
GValue* gvalue_from_kvp_value (const KvpValue *kval, GValue* val = nullptr);

KvpValue* kvp_value_from_gvalue (const GValue *gval);

#endif