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Antlr Error Handling

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share|improve this answer answered Aug 9 '13 at 2:31 Brad Mace 16.2k866104 add a comment| Your Answer draft saved draft discarded Sign up or log in Sign up using Google Note that the '@' exception specification of PCCTS 1.33 does not apply to ANTLR. Modifying Default Error Messages With Paraphrases The name or definition of a token in your lexer is rarely meaningful to the user of your recognizer or translator. When an exception is caught, execution resumes at that point. http://lanprolab.net/error-handling/antlr-4-error-handling.php

SemanticException Used to indicate syntactically valid, but nonsensical or otherwise bogus input was found on the input stream. MismatchedCharException Thrown by CharScanner.match() when it is looking for a character, but finds a different one on the input stream. Here is an example that catches an exception for the rule, for an alternate and for a labeled element: rule: a:A B C | D E exception // for alternate catch One big thing missing in all cases is location information. http://www.antlr2.org/doc/err.html

Antlr4 Error Handling Example

For example, instead of seeing T.java:1:9: expecting ID, found ';' you can have the parser generate: T.java:1:9: expecting an identifier, found ';' ANTLR provides an easy way to specify a string Such try{} blocks surround the generated code for the grammar element of interest (rule, alternate, token reference, or rule reference). 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

For example, instead of seeing T.java:1:9: expecting ID, found ';' you can have the parser generate: T.java:1:9: expecting an identifier, found ';' ANTLR provides an easy way to specify a string The generated code currently contains calls to sync(org.antlr.v4.runtime.Parser) after entering the decision state of a closure block ((...)* or (...)+). The default behavior of emitErrorMessage() is to print the error string to System.err. Antlr4 Error Handling All parser rules throw this exception.

CharStreamIOException The character input stream had an IO exception (e.g., CharBuffer.fill() can throw this). Antlr3 Error Reporting Render Frames as opposed to AVI? CharStreamException Something bad that happens on the character input stream. The error strategy implementation is responsible for calling Parser.notifyErrorListeners(java.lang.String) as appropriate.

Recent Posts Obscure Gradle Error: RSA premaster secret error Pulse 3.0 Alpha Pulse Admin UI Updates Pulse Roadmap Update Android: JUnit XML Reports with Gradle Archives March 2016 November 2015 September Antlr Error Listener Example The author specifies a parser-grammar option to load the lexer tokens. Thank you for the explanation! if (pce.getCause() instanceof RecognitionException) { RecognitionException re = (RecognitionException)pce.getCause(); ParserRuleContext context = (ParserRuleContext)re.getCtx(); } Edit 2: Based on your other answer, it appears that you don't actually want an exception, but

Antlr3 Error Reporting

TokenStreamException Indicates that something went wrong while generating a stream of tokens. The latter is geared towards actually modifying the behavior of the parser in response to errors, e.g. Antlr4 Error Handling Example Parameters:recognizer - the parser instance reportError voidreportError(Parserrecognizer, RecognitionExceptione) Report any kind of RecognitionException. Antlr Exceptions Because of this, you must be careful not to use any variables that would have been set by a successful match when an exception is caught.

I think this is the easiest of the 3 proposed solutions. –Kami Dec 29 '14 at 9:19 This is the right way to go. http://lanprolab.net/error-handling/antlr-syntax-error-handling.php In other words, a grammar that uses this vocabulary will also use the paraphrase. I've added some backstory to the question since it appears I might be swimming against the current. –Brad Mace Aug 9 '13 at 4:02 You should just write a The following diagram shows the hierarchy: Exception Description ANTLRException Root of the exception hiearchy. Antlr Rulecatch

Not the answer you're looking for? Reload to refresh your session. Note that IO exceptions are passed back as TokenStreamIOException's regardless of this option. click site To fix the former problem, we can add paraphrase options to our lexer tokens.

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. Antlr4 Throw Exception On Error write about erroneous input to the console) if we replace parser.setErrorHandler(new BailErrorStrategy()); with custom strategy, which leaves sync method intact: parser.setErrorHandler( new DefaultErrorStrategy() { /** Instead of recovering from exception {@code In ANTLR, parser exceptions are thrown when (a) there is a syntax error, (b) there is a failed validating semantic predicate, or (c) you throw a parser exception from an action.

Parameters:recognizer - the parser instance Returns:true if the parser is currently recovering from a parse error, otherwise false reportMatch voidreportMatch(Parserrecognizer) This method is called by when the parser successfully matches an

If nextToken() sees this, it will convert it to a TokenStreamIOException. HTH, Ibrahim November 10th, 2006 at 10:46 am Kunnummal says: Hi, Thanks for wonderful tutorial, I have really enjoyed this and got something out from it. TokenStreamException Indicates that something went wrong while generating a stream of tokens. Antlr Baseerrorlistener ANTLR Exception Hierarchy ANTLR-generated parsers throw exceptions to signal recognition errors or other stream problems.

Dirac delta function and correlation functions Is there a limit on how much is customizable on WordPress? For some reason I still cannot seem to catch the errors. 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. navigate to this website Sometimes you want exceptions to pop out of the lexer--usually when you want to abort the entire parsing process upon syntax error.

In ANTLR, parser exceptions are thrown when (a) there is a syntax error, (b) there is a failed validating semantic predicate, or (c) you throw a parser exception from an action. ANTLR will generate default error-handling code, or you may specify your own exception handlers. August 19th, 2009 at 1:54 am Manoj Rajagopalan says: Nice tutorial! Parser Exception Handling ANTLR generates recursive-descent recognizers.

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. If the rule successfully completed, this is null. where the label is only used for attaching exceptions to labeled elements. public class DescriptiveErrorListener extends BaseErrorListener { public static DescriptiveErrorListener INSTANCE = new DescriptiveErrorListener(); @Override public void syntaxError(Recognizer recognizer, Object offendingSymbol, int line, int charPositionInLine, String msg, RecognitionException e) { if

Now the user knows where the error occured. What is the difference between touch file and > file? Tweet This entry was posted on Tuesday, July 11th, 2006 at 5:44 pm and is filed under ANTLR, Java, Programming Languages, Technology. We recommend upgrading to the latest Safari, Google Chrome, or Firefox.

catch ... org.antlr.v4.runtime.DefaultErrorStrategy's sync would throw the InputMismatchException instead: switch (s.getStateType()) { case ATNState.BLOCK_START: case ATNState.STAR_BLOCK_START: case ATNState.PLUS_BLOCK_START: case ATNState.STAR_LOOP_ENTRY: // report error and recover if possible if ( singleTokenDeletion(recognizer)!=null ) { return; Used by TokenStreamSelector.retry() to force nextToken() of stream to re-enter and retry. Join them; it only takes a minute: Sign up Antlr error/exception handling up vote 3 down vote favorite After doing some research online I found that this would be the way

Let's take a look at the sorts of errors that are generated by the grammar as it stands. This exception is thrown automatically by failed, validating semantic predicates such as:a : A {false}? First, if you do nothing, ANTLR will generate a default exception handler for every parser rule. Specifying Parser Exception-Handlers You may attach exception handlers to a rule, an alternative, or a labeled element.

What is this syntax inside a GNU C statement expression extension? more hot questions question feed lang-java about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation Parser exception handling for grammar rules is a lot like exception handling in a language like C++ or Java.