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Antlr Default Error Handling


In this case, I haven't yet found a simple way to customise the error message. ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: Connection to failed. Custom Error Reporting To change the default error reporting behavior, override either the displayRecognitionError() or the emitErrorMessage() methods in the lexer and parser. This method has access to the exception that holds information about the error, and uses it to compose an error string that is then passed to the emitErrorMessage() method. http://dis-lb.net/error-handling/antlr-error-handling-c.php

If the error strategy successfully recovers from the match failure, this method returns the Token instance which should be treated as the successful result of the match. I hope this series of posts has piqued your interest in ANTLR and parsing, and maybe even helped you to solve some of your own problems. For an implementation based on Jim Idle's "magic sync" mechanism, see DefaultErrorStrategy.sync(org.antlr.v4.runtime.Parser). catch ...

Antlr Lexer Error Handling

What’s in This Book? Here's the answer: stackoverflow.com/questions/18581880/handling-errors-in-antl‌r-4 –james.garriss Oct 22 '14 at 14:46 add a comment| up vote 20 down vote +50 Since I've had a little bit of a struggle with the two Parameters:recognizer - the parser instance recoverInline TokenrecoverInline(Parserrecognizer) throws RecognitionException This method is called when an unexpected symbol is encountered during an inline match operation, such as Parser.match(int). SemanticException Used to indicate syntactically valid, but nonsensical or otherwise bogus input was found on the input stream.

Parser exception handling for grammar rules is a lot like exception handling in a language like C++ or Java. Reload to refresh your session. The best content for your career. Antlr4 Throw Exception On Error Here is an example that uses a bogus semantic exception (which is a subclass of RecognitionException) to demonstrate blasting out of the lexer: class P extends Parser; { public static void

The information you want is available in the exception that already gets thrown. –Sam Harwell Aug 9 '13 at 11:25 Gentle Reader, if you are like me, you're wondering Antlr Exception Handling You can have something listen on a socket for multiple input types without knowing which type will show up when. Edit: If you use DefaultErrorStrategy, the parse context exception will not be propagated all the way out to the calling code, so you'll be able to examine the exception field directly. Safari Logo Start Free Trial Sign In Support Enterprise Pricing Apps Explore Tour Prev Error Alternatives The Definitive ANTLR 4 Reference, 2nd Edition Next Chapter 10: Attributes and Actions Close The

An empire to last a hundred centuries Should I use "Search" or "Find” on my buttons? Antlr Baseerrorlistener For example, when parsing a command line for a shell like bash, there’s no point in trying to recover from errors. The first step is to turn off ANTLR's default error handling, so that the errors can be handled by pulse. MismatchedTokenException Thrown by Parser.match() when it is looking for a token, but finds a different one on the input stream.

Antlr Exception Handling

Thank you for the explanation! Terms Privacy Security Status Help You can't perform that action at this time. Antlr Lexer Error Handling Get 10 Days Free Recommended for you Prev Error Alternatives Next Chapter 10: Attributes and Actions Explore Tour Pricing Enterprise Government Education Queue App Learn Blog Contact Careers Press Resources Support Antlr4 Error Handling First, if you do nothing, ANTLR will generate a default exception handler for every parser rule.

Sign up for free to join this conversation on GitHub. http://dis-lb.net/error-handling/antlr-c-target-error-handling.php The default behavior of emitErrorMessage() is to print the error string to System.err. The error strategy implementation is responsible for calling Parser.notifyErrorListeners(java.lang.String) as appropriate. Generated Fri, 30 Sep 2016 19:19:04 GMT by s_hv977 (squid/3.5.20) Antlr Error Listener Example

more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed In particular, the methods used to match tokens in the parser base class (match et al) throw MismatchedTokenException. To fix the former problem, we can add paraphrase options to our lexer tokens. navigate here We can’t risk executing that command anyway, so the parser can bail out at the first sign of trouble.

First, if you do nothing, ANTLR will generate a default exception handler for every parser rule. Antlr Bailerrorstrategy The methods in the lexer base class used to match characters (match et al) throw analogous exceptions. We are the founders of zutubi, a company based in Sydney, Australia that makes software for software developers. Our flagship product is Pulse, an easy to use yet powerful and adaptable

ANTLR will generate default error-handling code, or you may specify your own exception handlers.

Here is an example of overriding displayRecognitionError(): @members { public void displayRecognitionError(String[] tokenNames, RecognitionException e) { String hdr = getErrorHeader(e); String msg = getErrorMessage(e, tokenNames); // Now do something with hdr B ; ANTLR generates: match(A); if (!(false)) throw new SemanticException("false"); match(B); You can throw this exception yourself during the parse if one of your actions determines that the input is wacked. Parameters:recognizer - the parser instancee - the recognition exception to report Overview Package Class Use Tree Deprecated Index Help Prev Class Next Class Frames No Frames All Classes Summary: Nested| Field| Antlr Error Strategy To get ANTLR to generate lexers that pass on RecognitionException's to the parser as TokenStreamException's, use the defaultErrorHandler=false grammar option.

I'm not sure whether this is an intended behavior, but in my opinion: something's just not right about it :) Antlr Project member sharwell commented Nov 6, 2013 You didn't include Specifying Parser Exception-Handlers You may attach exception handlers to a rule, an alternative, or a labeled element. I often use the following listener as a starting point, as it includes the name of the source file with the messages. his comment is here Parameters:recognizer - the parser instance Throws: RecognitionException - if the error strategy was not able to recover from the unexpected input symbol recover voidrecover(Parserrecognizer, RecognitionExceptione) throws RecognitionException

Try to get one again. RecognitionException A generic recognition problem with the input.