Ruby target

Author

Martin Traverso (mtraverso [at] acm [dot] org)

Status

The Ruby code generation target functional as of v3.0b4. Lexer and Parser generation are supported so far. Tree Parsers are not yet supported, though.

TODO

~~Return parameters~~
Scopes
ASTs
Error recovery
Memoization
Tree grammars

Some automated tests have been ported from the Java code generation target test suite, but more tests are needed (at least one for each string template)

Sample grammar

grammar Calculator;
options {
  language = Ruby;
}

evaluate returns [result]: r=expression { result = r };

expression returns [result]: r=mult (
    '+' r2=mult {
        r += r2
    }
  | '-' r2=mult {
        r -= r2
    }
  )* { result = r };

mult returns [result]: r=log (
    '*' r2=log {
        r *= r2
    }
  | '/' r2=log {
        r /= r2
    }
  | '%' r2=log {
        r %= r2
    }
  )* { result = r };

log returns [result]: 'ln' r=exp { result = Math::log(r) }
    | r=exp { result = r }
    ;

exp returns [result]: r=atom ('^' r2=atom { r = r ** r2 } )? { result = r }
    ;

atom returns [result]:
    n=INTEGER { result = $n.text.to_i }
  | n=DECIMAL { result = $n.text.to_f } 
  | '(' r=expression { result = r } ')'
  | 'PI' { result = Math::PI }
  | 'E' { result = Math::E }
  ;

INTEGER: DIGIT+;

DECIMAL: DIGIT+ '.' DIGIT+;

fragment
DIGIT: '0'..'9';

WS: (' ' | '\n' | '\t')+ { channel = 99 };