itch.io

OK, let's make a simple Colossal-Cave-Adventure-style two-word parser.

Lil's parsing patterns can get a little bit cryptic, but essentially what we want to break up user input is:

• Skip any leading spaces.
• Grab any characters up to a space or newline and call them "verb".
• Skip any spaces.
• Grab any characters up to a newline and call them "obj".

Which can be expressed as the pattern:

pat:"%*r %[verb]-.2r \n%*r %[obj]s\n"

I did a few tests in the Listener to make sure it was working as intended:

 pat parse "foo"
{"verb":"foo","obj":""}
 pat parse "  foo"
{"verb":"foo","obj":""}
 pat parse "foo bar"
{"verb":"foo","obj":"bar"}
 pat parse "foo bar\nbaz"
{"verb":"foo","obj":"bar"}
 pat parse "foo  bar\nbaz"
{"verb":"foo","obj":"bar"}

Now we can rework the input field's change[] handler to bundle this up and send the verb/object to the card script:

on change do
 if "\n" in me.text
  c:"%*r %[verb]-.2r \n%*r %[obj]s\n" parse me.text
  me.text:""
  typed[c.verb c.obj]
 end
end

In the card script, we'll have our actual game logic, a twisty maze of if statements:

on println x do
 log.text:log.text,x,"\n"
 log.scroll:999999
end
on typed verb obj do
 println["> %s %s" format verb,obj]
 if verb~"look"
  if obj~"flask"
   println["it is a flask."]
  elseif obj~"self"
   println["that's difficult unless your eyes are prehensile."]
  else
   println["ye see ye flask."]
  end
 elseif verb~"take"
  if obj~"flask"
   println["ye cannot take ye flask."]  
  else
   println["i don't see a %s anywhere here." format obj]
  end
 else
  println["ye is speakin' nonsense."]
 end
end

And our scintillating gameplay experience begins: