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/*
* Copyright (C) 2007-2010 Xagasoft, All rights reserved.
*
* This file is part of the libbu++ library and is released under the
* terms of the license contained in the file LICENSE.
*/
#ifndef BU_VARIANT_H
#define BU_VARIANT_H
#include <bu/string.h>
#include <typeinfo>
#include <bu/membuf.h>
#include <bu/formatter.h>
namespace Bu
{
class Formatter;
class Variant;
/** @cond DEVEL */
template<class t> class VariantType;
class VariantTypeRoot
{
public:
VariantTypeRoot();
virtual ~VariantTypeRoot();
virtual Bu::String toString() const=0;
virtual const std::type_info &getType() const=0;
virtual VariantTypeRoot *clone() const=0;
};
template<class t>
class VariantType : public VariantTypeRoot
{
friend class Variant;
private:
VariantType()
{
}
VariantType( const t &d ) :
data( d )
{
}
VariantType( const VariantType<t> &vt ) :
data( vt.data )
{
}
virtual ~VariantType()
{
}
public:
t &getData()
{
return data;
}
const t &getData() const
{
return data;
}
virtual Bu::String toString() const
{
MemBuf mb;
Formatter f( mb );
f << data;
return mb.getString();
}
virtual const std::type_info &getType() const
{
return typeid( data );
}
VariantType<t> operator=( const t &rhs )
{
data = rhs;
return *this;
}
virtual VariantTypeRoot *clone() const
{
return new VariantType<t>( *this );
}
private:
t data;
};
/** @endcond */
/**
* Store any data type and access it safely. Variant gives you a way to
* pass arbitrary data types around without having to worry about what
* type a variable is. It allows code to be easily extended and to manage
* data without having to know what type it is ahead of time.
*
* Because of the generic method that this class was implemented it may seem
* to have some drawbacks compared to other Variant classes you may have
* seen, however it is fairly easy to get it to do just about anything you
* may need. It is also very low overhead. On most compilers the class
* itself has only 3 words of overhead + the size of the variable you store
* in it. And, since many parts of it are templatized they can often be
* optimized quite a bit.
*/
class Variant
{
public:
Variant();
Variant( const Variant &v );
Variant( const char *t );
template<class t>
Variant( const t &v ) :
pCore( new VariantType<t>() )
{
(*dynamic_cast<VariantType<t> *>(pCore)) = v;
}
virtual ~Variant();
bool isSet() const;
Bu::String toString() const;
const std::type_info &getType() const;
Variant &operator=( const Variant &rhs );
template<class t>
Variant &operator=( const t &rhs )
{
if( pCore ) // && pCore->getType() != typeid(t) )
{
delete pCore;
pCore = NULL;
}
pCore = new VariantType<t>();
(*dynamic_cast<VariantType<t> *>(pCore)) = rhs;
return *this;
}
template<class t>
t &get()
{
if( !pCore )
{
throw Bu::ExceptionBase("No data!");
}
if( pCore->getType() != typeid(t) )
{
throw Bu::ExceptionBase("Invalid type conversion.");
}
return dynamic_cast<VariantType<t> *>(pCore)->getData();
}
template<class t>
t &get() const
{
if( !pCore )
{
throw Bu::ExceptionBase("No data!");
}
if( pCore->getType() != typeid(t) )
{
throw Bu::ExceptionBase("Invalid type conversion.");
}
return dynamic_cast<VariantType<t> *>(pCore)->getData();
}
template<class t>
void set( const t &val )
{
if( pCore && pCore->getType() != typeid(t) )
{
delete pCore;
pCore = NULL;
}
pCore = new VariantType<t>();
(*dynamic_cast<VariantType<t> *>(pCore)) = val;
}
template<class t>
bool isType() const
{
return pCore->getType() == typeid(t);
}
template<class t>
operator t()
{
if( !pCore )
{
throw Bu::ExceptionBase("No data!");
}
if( pCore->getType() != typeid(t) )
{
throw Bu::ExceptionBase("Invalid type conversion.");
}
return dynamic_cast<VariantType<t> *>(pCore)->getData();
}
template<class t>
operator t() const
{
if( !pCore )
{
throw Bu::ExceptionBase("No data!");
}
if( pCore->getType() != typeid(t) )
{
throw Bu::ExceptionBase("Invalid type conversion.");
}
return dynamic_cast<VariantType<t> *>(pCore)->getData();
}
private:
VariantTypeRoot *pCore;
};
template<class t>
Bu::Formatter &operator<<( Bu::Formatter &f, const VariantType<t> &vt )
{
return f << vt.toString();
}
Bu::Formatter &operator<<( Bu::Formatter &f, const Variant &v );
template<> Bu::String VariantType<int>::toString() const;
template<> Bu::String VariantType<bool>::toString() const;
};
#endif
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