protected override Expression CreateExpressionBody(Expression source, Expression destination, CompileArgument arg)
{
Expression convert = source;
var sourceType = arg.SourceType;
var destinationType = arg.DestinationType;
if (sourceType != destinationType)
{
if (sourceType.IsNullable())
{
convert = Expression.Convert(convert, sourceType.GetGenericArguments()[0]);
}
convert = ReflectionUtils.BuildUnderlyingTypeConvertExpression(convert, sourceType, destinationType);
if (convert.Type != destinationType)
{
convert = Expression.Convert(convert, destinationType);
}
if (arg.MapType != MapType.Projection &&
(!arg.SourceType.GetTypeInfo().IsValueType || arg.SourceType.IsNullable()))
{
//src == null ? default(TDestination) : convert(src)
var compareNull = Expression.Equal(source, Expression.Constant(null, sourceType));
convert = Expression.Condition(compareNull, Expression.Constant(destinationType.GetDefault(), destinationType), convert);
}
}
return(convert);
}