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 };