[antlr-interest] On to the next issue: error(211)

[Hendrik Maryns]

HI,

Ok, so the ‘token file not found’ issue seems to be bogus, but here is
the next problem with my grammar:

error(211): fsqTreeParser.g:68:3: [fatal] rule body has non-LL(*)
decision due to recursive rule invocations reachable from alts 3,5.
Resolve by left-factoring or using syntactic predicates or using
backtrack=true option.

Strangely, the parser grammar contains the exact same rule, but does not
give this error message.

Here is the relevant rule:

body returns [Formula result]
  : label { $result = $label.result; }
  | atomic { $result = $atomic.result; }
  | unary { $result = $unary.result; }
  | binary { $result = $binary.result; }
  | n_ary { $result = $n_ary.result; }
  | quantor { $result = $quantor.result; }
  ;

Indeed, the unary, binary, n_ary and quantor rules (indirectly) refer to
formula:

formula returns [Formula result]
  : ^(FORMULA body) { $result = $body.result; }
  ;

What would be the proper thing to do here?  Adding backtrack=true does
fix it, but I am not sure whether that is a good idea?

You might notice that I am trying to implement a parser for some logic
here.

H.
-- 
Hendrik Maryns
http://tcl.sfs.uni-tuebingen.de/~hendrik/
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