Type of extension required for dynamic content injection using place holders

[mattadamson]

Related to

https://github.com/Swagger2Markup/swagger2markup/issues/142

We'd like to create some kind of extension which allows syntax such as

{{SQL='SELECT firstCol, secondCol FROM MyModelDefnition'',Model=Contact',Cols='First column', ;'Second column'}}

So within the extension the content within {{ and }} is replaced with code logic e.g. query to a database to build a ascii doc formatted table. Then when finished the token is completely replaced with this custom mark up.

From the many extensions supported which is most appropriate for this as I'm not clear?

Thanks