Hello Victor, This question that I posted last week describes how I am raising an error on unwanted input before EOF which, I think, is similar to what you are trying to do...
http://antlr.1301665.n2.nabble.com/best-practice-for-unwanted-input-before-EOF-td5964792.html I was looking for a better way (no one has replied so far) but it does work. Michael On 4 February 2011 15:11, Victor Giordano <[email protected]> wrote: > Hello people, two days a posted this problem and i still having troubles > with this matter, pliz give a hand, if you can of course.... > I need to handle the errors of parsing in order to display a nice user > message. > > I am watching when i use the generated lexer and parser (Generated from > the LinearMath grammar below) in a java application is that do really > emit somekind of warning about two thinks: > > 1)extraneous input '<some_token>' expecting EOF *Only when a append the > EOF token at the end of the rule* > 2)required (...)+ loop did not match anything at input <some_token>' > *Only when i use the '+' quantity token modifier* > > where <some_token> there is actually token. > > The matter is, again, how do i catch in a exception those errors. I show > below the grammar with an input example to try for yourself: > > grammar LinearMath; > > tokens > { > PLUS = '+'; > MINUS = '-'; > MUL = '*'; > DIV = '/'; > } > > inecuation: linexpr ((RELATIONSHIP) linexpr)+ EOF!; > catch [UnwantedTokenException ute] > { > System.out.println ("inecuation UnwantedTokenException " + > ute.toString()); > throw ute; > } > > linexpr : (MINUS|PLUS)? linterm ((PLUS|MINUS) linterm)* EOF; > > linterm : factor? ID; > > expr returns [double value] > : e=term {$value = $e.value;} > ( PLUS e=term {$value += $e.value;} > | MINUS e=term {$value -= $e.value;} > )*; > > term returns [double value] > : f=factor {$value = $f.value;} > ( MUL f=factor {$value *= $f.value;} > | DIV f=factor {$value /= $f.value;} > )*; > > factor returns [double value] > : DOUBLE {$value = Double.parseDouble($DOUBLE.text);} > | '(' e=expr ')'{$value = $e.value;}; > > ID : ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*; > > DOUBLE > : ('0'..'9')+ > | ('0'..'9')+ '.' ('0'..'9')* EXPONENT? > | '.' ('0'..'9')+ EXPONENT? > | ('0'..'9')+ EXPONENT > ; > > fragment EXPONENT : ('e'|'E') ('+'|'-')? ('0'..'9')+ ; > > NEWLINE:'\r'? '\n' { $channel = HIDDEN; }; > > WS : (' '|'\t'|'\n'|'\r')+ { $channel = HIDDEN; }; > > > RELATIONSHIP : '<'|'<='|'='|'>'|'>='; > > and with the following input: "x< y x" > that isn't a valid inecuation beacause the y x must have a binary > aritmetic operator (PLUS OR MINUS). The parser do his job very well, he > consume the "x" then "<" later "y" and when it reachs the seconds "x" it > emits an "UnwantedTokenException". The think is, that i am not being > able to catch it, and display an error to the final user. Look that i am > using to parse that input the inecuation "rule". > > -------------------------------------------------------------------------- > 2) Other thing is about invalid tokens, i manage to treat then > overriding a member function of the lexer called nextToken(), like this: > > @lexer::members > { > @Override > public Token nextToken() > { > while (true) { > state.token = null; > state.channel = Token.DEFAULT_CHANNEL; > state.tokenStartCharIndex = input.index(); > state.tokenStartCharPositionInLine = > input.getCharPositionInLine(); > state.tokenStartLine = input.getLine(); > state.text = null; > if ( input.LA(1)==CharStream.EOF ) { > return Token.EOF_TOKEN; > } > try { > mTokens(); > if ( state.token==null ) { > emit(); > } > else if ( state.token==Token.SKIP_TOKEN ) { > continue; > } > return state.token; > } > catch (RecognitionException re) { > reportError(re); > throw new RuntimeException("Invalid Character : " + > (char) (re.c)); > // or throw Error > } > } > } > } > ¿It's that the correct way? > > Ok, so far this. > Sorry for the bombing III of emails!. Thanks for advance. > Víctor. > > > El 03/02/2011 12:36 a.m., Victor Giordano escribió: >> I am watching when i use the generated lexer and parser (Generated from >> the LinearMath grammar below) in a java application is that do really >> emit somekind of warning about two thinks: >> >> 1)extraneous input '<some_token>' expecting EOF *Only when a append the >> EOF token at the end of the rule* >> 2)required (...)+ loop did not match anything at input <some_token>' >> *Only when i use the '+' quantity token modifier* >> >> where <some_token> there is actually token. >> >> In fact the warnings is actually are a strings sended to the standart >> error. >> >> The matter is, again, how do i do to manage those errors altering normal >> flow with a real exception and treating it like one. >> Ok, so far this. >> Sorry for the bombing of emails!. Thanks for advance. >> Víctor. > > List: http://www.antlr.org/mailman/listinfo/antlr-interest > Unsubscribe: > http://www.antlr.org/mailman/options/antlr-interest/your-email-address > List: http://www.antlr.org/mailman/listinfo/antlr-interest Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-email-address -- You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en.
