Command Parsing

[da...@nautoguide.com]

I am looking to build a simple parser to find commands such as:-

"where am i"
"what is my location"
"find where i am"

These could be in longer sentence such as

"help me find where i am"
"please could you tell me my location"
"what is my current position"

I was hoping to achieve this with:-

location_request = "am i"/"i am"/"my location"/"location"/"position"
location_predicate = "where"/"what"/"find"/"tell"

And a top level rule that says:-

<optional stuff> +location_predicate + <option stuff> + location_request + <optional stuff>

I am not sure how to define the <optional stuff> to ignore the location_request and location_predicate rules

Can this be done?

TIA
Dave

[Samuel Crow]

Natural language processing is possible but I've heard that other parser generators may be better suited to it than PEGs.  The terms "natural language parser" are good search terms though.

[Futago-za Ryuu]

Samuel is right that in most cases of parsing natrual languages, PEG.js might not be the right tool to use, but it is possible:

start
  = _ predicate:LocationPredicate _ request:LocationRequest _ {
     return { predicate, request };
   }

LocationRequest "Request"

  = "am i"
  / "i am"
  / "my location"
  / "location"
  / "position"

LocationPredicate "Predicate"

  = "where"
  / "what"
  / "find"
  / "tell"

_ "Optional Stuff"
  = (!(LocationRequest / LocationPredicate) .)*

You can test the above example at: https://pegjs.org/online