public static int CanBeConverted(this Type sourceType, Type targetType)
{
if (sourceType == targetType)
{
return(0);
}
try
{
var e = Expression.Convert(Expression.Parameter(sourceType), targetType);
return(1);
}
catch (Exception)
{
var method = ConverterHelper.GetConvertMethod(sourceType, targetType);
if (method != null)
{
return(2);
}
}
return(-1);
}
/// <summary>
/// return an expression of convertion if targetype are differents
/// </summary>
/// <param name="self"></param>
/// <param name="targetType"></param>
/// <returns></returns>
public static Expression ConvertIfDifferent(this Expression self, Type targetType)
{
Expression result = null;
Type sourceType = self.ResolveType();
if (sourceType != targetType)
{
//if (self is ConstantExpression c)
//{
// result = c.Value.AsConstant(targetType);
// if (result.Type != targetType)
// result = Expression.Convert(result, targetType);
//}
//else
//{
try
{
result = Expression.Convert(self, targetType);
}
catch (Exception) // not managed
{
var method = ConverterHelper.GetConvertMethod(sourceType, targetType);
if (method != null)
{
var parameters = method.GetParameters();
Expression[] arguments = new Expression[parameters.Length];
if (parameters[0].ParameterType == sourceType)
{
arguments[0] = self;
}
else if (typeof(IFormatProvider).IsAssignableFrom(parameters[0].ParameterType))
{
arguments[0] = Expression.Constant(CultureInfo.CurrentCulture);
}
else if (parameters[0].ParameterType.IsAssignableFrom(sourceType))
{
arguments[0] = ConvertIfDifferent(self, parameters[0].ParameterType);
}
else if (parameters[0].ParameterType == typeof(Type))
{
arguments[0] = Expression.Constant(targetType);
}
else
{
}
if (parameters[1].ParameterType == sourceType)
{
arguments[1] = self;
}
else if (typeof(IFormatProvider).IsAssignableFrom(parameters[1].ParameterType))
{
arguments[1] = Expression.Constant(CultureInfo.CurrentCulture);
}
else if (parameters[1].ParameterType.IsAssignableFrom(sourceType))
{
arguments[1] = ConvertIfDifferent(self, parameters[0].ParameterType);
}
else if (parameters[1].ParameterType == typeof(Type))
{
arguments[1] = Expression.Constant(targetType);
}
else
{
}
if (method is MethodInfo m)
{
if (m.IsStatic)
{
result = Expression.Call(null, m, arguments);
}
else
{
result = Expression.Call(self, m, arguments);
}
}
else if (method is ConstructorInfo ctor)
{
result = Expression.New(ctor, arguments);
}
}
if (result == null)
{
if (targetType != typeof(object))
{
result = self.ConvertIfDifferent(typeof(object));
result = result.ConvertIfDifferent(targetType);
}
else
{
throw;
}
}
}
//}
}
else
{
result = self;
}
return(result);
}