ObjectsVariant.h

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#pragma once
 
#include <alib/variant>
#include <core/stringApi.hpp>
 
namespace core {
 
template < class ... Types >
struct stringApi < ext::variant < Types ... > > {
    static ext::variant < Types ... > parse ( ext::istream & input );
    static bool first ( ext::istream & input );
    static void compose ( ext::ostream & output, const ext::variant < Types ... > & container );
 
private:
    class VariantStringApiCallback {
        ext::ostream & m_out;
 
    public:
        VariantStringApiCallback ( ext::ostream & out ) : m_out ( out ) {
        }
 
        template < class ValueType >
        void operator ( ) ( const ValueType & value ) {
            stringApi < ValueType >::compose ( m_out, value );
        }
    };
 
    template < class T, class R, class ... Ts >
    static ext::variant < Types ... > parse ( ext::istream & input ) {
        if ( stringApi < T >::first ( input ) )
            return ext::variant < Types ... > ( stringApi < T >::parse ( input ) );
        else
            return parse < R, Ts ... > ( input );
    }
 
    template < class T >
    static ext::variant < Types ... > parse ( ext::istream & input ) {
        return ext::variant < Types ... > ( stringApi < T >::parse ( input ) );
    }
};
 
template < class ... Types >
ext::variant < Types ... > stringApi < ext::variant < Types ... > >::parse ( ext::istream & input ) {
    return parse < Types ... > ( input );
}
 
template < class ... Types >
bool stringApi < ext::variant < Types ... > >::first ( ext::istream & input ) {
    return ( ... && stringApi < Types >::first ( input ) );
}
 
template < class ... Types >
void stringApi < ext::variant < Types ... > >::compose ( ext::ostream & output, const ext::variant < Types ... > & container ) {
    ext::visit ( VariantStringApiCallback ( output ), container );
}
 
} /* namespace core */