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peerplays-fc/include/fc/value_cast.hpp
Daniel Larimer 3d56a96d4e major updates to stream,reflect,value,and json 
- removed polymorphic reflection, made static_reflect default because
  there are cases such as deserializing an array that you need more
  information than the runtime reflection can provide such as the
  ability to resize arrays and know the array content type.

- refactored iostream, sstream, fstream to be much simpler, fewer
  indirections, and fixed getline.

- json parsing works using code from mace.
- value is reimplemented based upon mace::rpc::value and no longer uses
  the runtime reflection that was removed.

- moved the typename utility to its own header
2012-10-21 02:28:59 -04:00

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#pragma once
#include <fc/reflect.hpp>
#include <fc/value.hpp>
#include <fc/exception.hpp>
#include <fc/lexical_cast.hpp>
#include <fc/numeric_cast.hpp>
#include <fc/value_io.hpp>
namespace fc {
namespace detail {
template<typename T>
struct cast_visitor : value::const_visitor {
cast_visitor( T& out )
:m_out(out){}
virtual void operator()( const int8_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const int16_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const int32_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const int64_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const uint8_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const uint16_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const uint32_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const uint64_t& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const float& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const double& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const bool& v ){ m_out = fc::numeric_cast<T>(v); }
virtual void operator()( const fc::string& v ) { m_out = fc::lexical_cast<T>(v); }
virtual void operator()( const value::object& ) { FC_THROW_MSG("bad cast"); }
virtual void operator()( const value::array& ) { FC_THROW_MSG("bad cast"); }
virtual void operator()( ) { FC_THROW_MSG("bad cast"); }
private:
T& m_out;
};
template<>
struct cast_visitor<fc::string> : value::const_visitor {
cast_visitor( fc::string& out )
:m_out(out){}
virtual void operator()( const int8_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const int16_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const int32_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const int64_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const uint8_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const uint16_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const uint32_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const uint64_t& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const float& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const double& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const bool& v ){ m_out = fc::lexical_cast<fc::string>(v); }
virtual void operator()( const fc::string& v ){ m_out = v; }
virtual void operator()( const value::object& ) { FC_THROW_MSG("bad cast"); }
virtual void operator()( const value::array& ) { FC_THROW_MSG("bad cast"); }
virtual void operator()( ) { FC_THROW_MSG("bad cast"); }
private:
fc::string& m_out;
};
template<>
struct cast_visitor<value::array> : value::const_visitor {
cast_visitor( value::array& out )
:m_out(out){}
virtual void operator()( const int8_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const int16_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const int32_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const int64_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint8_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint16_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint32_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint64_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const float& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const double& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const bool& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const fc::string& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const value::object& ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const value::array& a ) { m_out = a; }
virtual void operator()( ) { FC_THROW_MSG("bad cast");}
private:
value::array& m_out;
};
template<>
struct cast_visitor<value::object> : value::const_visitor {
cast_visitor( value::object& out )
:m_out(out){}
virtual void operator()( const int8_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const int16_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const int32_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const int64_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint8_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint16_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint32_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const uint64_t& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const float& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const double& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const bool& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const fc::string& v ){ FC_THROW_MSG("bad cast");}
virtual void operator()( const value::object& a ) { m_out = a; }
virtual void operator()( const value::array& ) { FC_THROW_MSG("bad cast");}
virtual void operator()( ) { FC_THROW_MSG("bad cast");}
private:
value::object& m_out;
};
template<>
struct cast_visitor<void> : value::value::const_visitor {
virtual void operator()( const int8_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const int16_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const int32_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const int64_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const uint8_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const uint16_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const uint32_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const uint64_t& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const float& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const double& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const bool& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const fc::string& v ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const value::object& a ) { FC_THROW_MSG("bad cast");}
virtual void operator()( const value::array& ) { FC_THROW_MSG("bad cast");}
virtual void operator()( ) { }
};
template<typename IsReflected=fc::false_type>
struct cast_if_reflected {
template<typename T>
static T cast( const value& v ) {
T out;
v.visit(cast_visitor<T>(out));
return out;
}
};
template<>
struct cast_if_reflected<fc::true_type> {
template<typename T>
static T cast( const value& v ) {
T tmp;
unpack(v,tmp);
return tmp;
}
};
class value_visitor;
struct value_holder {
virtual ~value_holder();
virtual const char* type()const;
virtual void visit( value::const_visitor&& v )const;
virtual void visit( value_visitor&& v );
virtual void clear();
virtual size_t size()const;
virtual void resize( size_t );
virtual void reserve( size_t );
virtual value& at( size_t );
virtual const value& at( size_t )const;
virtual void push_back( value&& v );
virtual value_holder* move_helper( char* c );
virtual value_holder* copy_helper( char* c )const;
};
} // namespace detail
/**
* Convert from value v to T
*
* Performs the following conversions
* true -> 1.0, 1, "true"
*
* Not all casts are 'clean', the following conversions
* could cause errors:
*
* signed int -> unsigned
* large int -> smaller int
* real -> int
* non-numeric string -> number
* object -> string or number
* array -> string or number
* number,string,array -> object
*/
template<typename T>
T value_cast( const value& v ) {
return detail::cast_if_reflected<typename fc::reflector<T>::is_defined>::template cast<T>(v);
}
template<typename T>
value::value( T&& v ) {
new (holder) detail::value_holder();
fc::pack( *this, std::forward<T>(v) );
}
}
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