internal static ActivityWithResult TryCreateLiteral(Type type, string expressionText, ParserContext context)
{
//try easy way first - look if there is a type conversion which supports conversion between expression type and string
TypeConverter literalValueConverter = null;
bool isQuotedString = false;
if (CanTypeBeSerializedAsLiteral(type))
{
bool shouldBeQuoted = typeof(string) == type;
//whether string begins and ends with quotes '"'. also, if there are
//more quotes within than those begining and ending ones, do not bother with literal - assume this is an expression.
isQuotedString = shouldBeQuoted &&
expressionText.StartsWith("\"", StringComparison.CurrentCulture) &&
expressionText.EndsWith("\"", StringComparison.CurrentCulture) &&
expressionText.IndexOf("\"", 1, StringComparison.CurrentCulture) == expressionText.Length - 1;
//if expression is a string, we must ensure it is quoted, in case of other types - just get the converter
if ((shouldBeQuoted && isQuotedString) || !shouldBeQuoted)
{
literalValueConverter = TypeDescriptor.GetConverter(type);
}
}
//if there is converter - try to convert
if (null != literalValueConverter && literalValueConverter.CanConvertFrom(context, typeof(string)))
{
try
{
var valueToConvert = isQuotedString ? expressionText.Substring(1, expressionText.Length - 2) : expressionText;
var converterValue = literalValueConverter.ConvertFrom(context, CultureInfo.CurrentCulture, valueToConvert);
//ok, succeeded - create literal of given type
var concreteExpType = typeof(Literal <>).MakeGenericType(type);
return((ActivityWithResult)Activator.CreateInstance(concreteExpType, converterValue));
}
catch { }
}
return(null);
}
internal static string GetExpressionString(Activity expression, ModelItem owner)
{
ParserContext context = new ParserContext(owner);
return(ExpressionHelper.GetExpressionString(expression, context));
}