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peerplays-fc/include/fc/value_cast.hpp
Daniel Larimer b568936c5e adding tuple support to value
2012-10-26 01:00:06 -04:00

197 lines
9.8 KiB
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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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