Multiple alternatives with the same label, only the last gets anything assigned to it

I have some non-reserved keywords I'm matching with rules like:

kFOO = {self.input.LT(1).text.lower() == 'foo'}? ID;

Where the ID token is a standard alpha-numeric string. These kinds of rules work great, except when I try to do something like this:

some_rule
@after { do_something_with($t.text) }
  : t=kWORD1
  | t=kWORD2
  | t=kWORD3
  ;

In the generated pars开发者_运维百科er, the kWORD1 and kWORD2 rule functions don't return anything, but the kWORD3 function does. As well, in the some_rule function, only the block trying to match kWORD3 assign the return value to t. The other two invocations don't reference t in any way.

(Also, I expected the following to work, but it did not, I suspect for the same underlying reason.

some_rule
@after { do_something_with($t.text) }
  : t=( kWORD1
  | kWORD2
  | kWORD3)
  ; 

Nothing gets assigned to t under any conditions.)

However, the following DOES work as expected:

some_rule
@after { do_something_with($t1.text or $t2.text or $t3.text) }
  : t1=kWORD1
  | t2=kWORD2
  | t3=kWORD3
  ;

Each of the matching functions is generated to return a value, and each of the blocks matching the keyword rules in some_rule assigns the return value to their label. The problem with this solution is it gets a little excessive when there are several more alternatives.

Half of me cries "BUG!" but this is the first antlr project I've done, so more likely there's something I don't understand.

What's the best way to do what it is I'm trying to do here?

Besides the fact that .toLower() never matches FOO, I believe this is due to the fact that kWORD1 is another type of kWORD2 etc. but something that might work is this:

kWORD [String pre]
: {self.input.LT(1).text.lower() == $pre}? ID;

some_rule
@after { do_something_with($t.text) }
  : t=kWORD['word1']
  | t=kWORD['word2']
  | t=kWORD['word3']
  ;

untested though.