Ask HN:Your views on unique search engine problem

I am building an index of applications and would like to allow the users to search using a semi open text search. i.e some template the user has to complete words in.

Looking for some reference to existing solutions where the user will complete a sentence like:

for examples

I am looking fro an app that [verb] [noun]

or :

I am looking for an alternative to [app name]

and is being helped by the UI to tunnel the search to available options.

any ideas / pointers will be welcome.