} // func ConvertObjectExpression
private static Expression ConvertExpression(Lua runtime, Token tokenStart, Expression expr, Type toType)
{
// dynamic convert
if (LuaEmit.TryConvert(expr, expr.Type, toType, runtime.GetConvertBinder, out var result))
{
return((Expression)result);
}
else
{
throw ParseError(tokenStart, ((LuaEmitException)result).Message);
}
} // func ConvertExpression
} // ctor
public override DynamicMetaObject FallbackConvert(DynamicMetaObject target, DynamicMetaObject errorSuggestion)
{
if (!target.HasValue)
{
return(Defer(target));
}
if (target.Value == null) // get the default value
{
Expression expr;
var restrictions = target.Restrictions.Merge(BindingRestrictions.GetInstanceRestriction(target.Expression, null));
if (Type == typeof(LuaResult)) // replace null with empty LuaResult
{
expr = Expression.Property(null, Lua.ResultEmptyPropertyInfo);
}
else if (Type == typeof(string)) // replace null with empty String
{
expr = Expression.Field(null, Lua.StringEmptyFieldInfo);
}
else
{
expr = Expression.Default(Type);
}
return(new DynamicMetaObject(Lua.EnsureType(expr, ReturnType), restrictions));
}
else // convert the value
{
var restrictions = target.Restrictions.Merge(BindingRestrictions.GetTypeRestriction(target.Expression, target.LimitType));
object result;
if (LuaEmit.TryConvert(target.Expression, target.LimitType, Type, null, out result))
{
return(new DynamicMetaObject(Lua.EnsureType((Expression)result, ReturnType), restrictions));
}
else if (errorSuggestion == null)
{
if (result == null)
{
throw new ArgumentNullException("expr", "LuaEmit.TryConvert does not return a expression.");
}
return(new DynamicMetaObject(ThrowExpression(((LuaEmitException)result).Message, ReturnType), restrictions));
}
else
{
return(errorSuggestion);
}
}
} // func FallbackConvert
