Antlr Syntax Error Unexpected Token
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Syntax Error Unexpected Token U
AST tree as expected. I generated lexer and parser for C# and test it for some input. tree antlr grammar share|improve this question edited Apr 30 '11 at 19:10 Bart Kiers 106k23187216 asked Apr 30 '11 at 19:07 Vladimir Radojicic 3371518 add a comment| 1 Answer 1 active oldest votes up vote 2 down vote accepted When parsing the source: variable a, b, c : int; you're trying to construct an AST that looks like: variable variable variable / | \ a b c / | \ int int int But since 'variable' and TYPE are always the same token, I see no need to create all those duplicate nodes. Why not just do: declaration : 'variable' IDENTIFIER ( ',' IDENTIFIER)* ':' TYPE ';' -> ^('variable' TYPE IDENTIFIER+) ; which will create an AST like: variable / | | \ int a b c ? share|improve this answer edited Apr 30 '11 at 19:17 answered Apr 30 '11 at 19:11 Bart Kiers 106k23187216 I tried this, and it says Decision can match input such as variable using multiple alternatives 1,2 –Vladimir Radojicic Apr 30 '11 at 19:15 @Vladimir, I edited my answer. –Bart Kiers Apr 30 '11 at 19:17 Well this is solved :) –Vladimir Radojicic Apr 30 '11 at 19:25 Thanks a lot, this works, (I have different errors now :) They are not connected with this.. –Vladimir Radojicic Apr 3
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Syntax Error Unexpected Token O
Messages sorted by: [ date ] [ syntax error unexpected token illegal thread ] [ subject ] [ author ] I'm syntax error unexpected token e trying to convert a v2 grammar to v3. I'm getting lots of errors about ':' tokens. http://stackoverflow.com/questions/5844012/antlr-syntax-error-unexpected-token Here's a fairly minimal testcase I've made while trying to track this down: grammar AS3Parser; x : y | z ; y : "class" ; z : "package"; Here's the output I get, http://www.antlr3.org/pipermail/antlr-interest/2006-August/017325.html ANTLR Parser Generator Early Access Version 3.0b3 (July 21, 2006) 1989-2006 3:3: syntax error: antlr: src/antlr/org/asdt/core/internal/antlr/as3.g3.testcase:3:3: unexpected token: : 4:5: syntax error: antlr: src/antlr/org/asdt/core/internal/antlr/as3.g3.testcase:4:5: unexpected token: "package" src/antlr/org/asdt/core/internal/antlr/as3.g3.testcase:2:9: reference to undefined rule: z src/antlr/org/asdt/core/internal/antlr/as3.g3.testcase:2:5: reference to undefined rule: y I'm sure it's something really obvious, but I just don't see it. help! dave -- http://david.holroyd.me.uk/ Previous message: [antlr-interest] [V3] '%' in java code obtains unexpected StringTemplate error Next message: [antlr-interest] unexpected token: : Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the antlr-interest mailing list
Over the past four parts, I have illustrated how to parse and evaluate boolean expressions http://www.alittlemadness.com/category/antlr/ using ANTLR. The grammar presented is in those parts is based http://www.antlr2.org/doc/err.html on real code in pulse. Although it works as presented, there are a couple of items to polish up, one of which I have solved, and the other of which I have not yet been able to solve. Error Reporting As pulse allows users to enter syntax error their own boolean expressions (to configure when they receive build notifications), decent error reporting is paramount. The first step is to turn off ANTLR's default error handling, so that the errors can be handled by pulse. This is done by setting the defaultErrorHandler option to false: class NotifyConditionParser extends Parser; options { buildAST=true; defaultErrorHandler=false; } With that syntax error unexpected done, the ANTLR-generated code will throw exceptions on errors. Let's take a look at the sorts of errors that are generated by the grammar as it stands. Case 1: Unrecognised word: $ java NotifyConditionParserTest "changed or tuer" Caught error: unexpected token: tuer Case 2: Unrecognised character: $ java NotifyConditionParserTest "6 and false" Caught error: unexpected char: '6' Case 3: Illegal expression structure $ java NotifyConditionParserTest "state.change or or success" Caught error: unexpected token: or Case 4: Unbalanced parentheses $ java NotifyConditionParserTest "failure or (changed and success" Caught error: expecting RIGHT_PAREN, found 'null' Most of these messages are not too bad, at least they are on the right track. Case 4 is certainly the worst of the lot, although the information is accurate it is not exactly user friendly. We'll get back to that later. One big thing missing in all cases is location information. I figured that ANTLR must have a way to retrieve the information, and a little digging uncovered it. All of the above messages are ge
no alternative of a production in either the parser or lexer, then a NoViableAltException is thrown. The methods in the lexer base class used to match characters (match et al) throw analogous exceptions. ANTLR will generate default error-handling code, or you may specify your own exception handlers. Either case results (where supported by the language) in the creation of a try/catch block. Such try{} blocks surround the generated code for the grammar element of interest (rule, alternate, token reference, or rule reference). If no exception handlers (default or otherwise) are specified, then the exception will propagate all the way out of the parser to the calling program. ANTLR's default exception handling is good to get something working, but you will have more control over error-reporting and resynchronization if you write your own exception handlers. Note that the '@' exception specification of PCCTS 1.33 does not apply to ANTLR. ANTLR Exception Hierarchy ANTLR-generated parsers throw exceptions to signal recognition errors or other stream problems. All exceptions derive from ANTLRException. The following diagram shows the hierarchy: Exception Description ANTLRException Root of the exception hiearchy. You can directly subclass this if you want to define your own exceptions unless they live more properly under one of the specific exceptions below. CharStreamException Something bad that happens on the character input stream. Most of the time it will be an IO problem, but you could define an exception for input coming from a dialog box or whatever. CharStreamIOException The character input stream had an IO exception (e.g., CharBuffer.fill() can throw this). If nextToken() sees this, it will convert it to a TokenStreamIOException. RecognitionException A generic recognition problem with the input. Use this as your "catch all" exception in your main() or other method that invokes a parser, lexer, or treeparser. All parser rules throw this exception. MismatchedCharException Thrown by CharScanner.match() when it is looking for a character, but finds a different one on the input stream. MismatchedTokenException Thrown by Pa