Antlr Syntax Error Handling
Contents |
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About antlr4 error handling Us Learn more about Stack Overflow the company Business Learn more about hiring
Antlr Error Listener Example
developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the antlr4 throw exception on error Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Handling Antlr Syntax Errors or how
Antlr Baseerrorlistener
to give a better message on unexpected token up vote 4 down vote favorite 1 We have the following sub-part of an Antlr grammar: signed_int : SIGN? INT ; INT : '0'..'9'+ ; When someone enters a numeric value everything is fine, but if they mistakenly type something like 1O (one and capital o) we get a cryptic error message like: error 1 : Missing token at antlr4 lexer error handling offset 14 near [Index: 0 (Start: 0-Stop: 0) ='
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us
Antlr Error Strategy
Learn more about Stack Overflow the company Business Learn more about hiring developers or
Antlr Error Handling Example
posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow antlr bailerrorstrategy Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Handling errors in ANTLR4 up vote 24 down vote http://stackoverflow.com/questions/10386499/handling-antlr-syntax-errors-or-how-to-give-a-better-message-on-unexpected-token favorite 10 The default behavior when the parser doesn't know what to do is to print messages to the terminal like: line 1:23 missing DECIMAL at '}' This is a good message, but in the wrong place. I'd rather receive this as an exception. I've tried using the BailErrorStrategy, but this throws a ParseCancellationException without a message (caused by a InputMismatchException, also without a message). Is there http://stackoverflow.com/questions/18132078/handling-errors-in-antlr4 a way I can get it to report errors via exceptions while retaining the useful info in the message? Here's what I'm really after--I typically use actions in rules to build up an object: dataspec returns [DataExtractor extractor] @init { DataExtractorBuilder builder = new DataExtractorBuilder(layout); } @after { $extractor = builder.create(); } : first=expr { builder.addAll($first.values); } (COMMA next=expr { builder.addAll($next.values); })* EOF ; expr returns [List
ANTLRErrorStrategy All Known Implementing Classes: BailErrorStrategy, DefaultErrorStrategy public interface ANTLRErrorStrategy The interface for https://github.com/antlr/antlr4/issues/396 defining strategies to deal with syntax errors encountered during a parse by ANTLR-generated parsers. We error handling distinguish between three different kinds of errors: The parser could not figure out which path to take in the ATN (none of the available alternatives could possibly match) The current input antlr syntax error does not match what we were looking for A predicate evaluated to false Implementations of this interface report syntax errors by calling Parser.notifyErrorListeners(java.lang.String). TODO: what to do about lexers Method Summary Methods Modifier and Type Method and Description boolean inErrorRecoveryMode(Parserrecognizer) Tests whether or not recognizer is in the process of recovering from an error. void recover(Parserrecognizer, RecognitionExceptione) This method is called to recover from exception e. Token recoverInline(Parserrecognizer)
Support Search GitHub This repository Watch 188 Star 1,678 Fork 519 antlr/antlr4 Code Issues 216 Pull requests 39 Projects 0 Wiki Pulse Graphs New issue Accumulating / Collecting Errors via ErrorListener to handle after the Parse #396 Closed jonathandandries opened this Issue Jan 7, 2014 · 4 comments Projects None yet Labels comp:runtime status:not-fixing Milestone No milestone Assignees No one assigned 2 participants jonathandandries commented Jan 7, 2014 The ErrorListener mechanism in Antlr4 is great for logging and making decisions about syntax errors as they occur during a parse, but it can get better for batch error handling after the parse is finished. There are a number of reasons you might want to handle errors after the parse finishes, including: we need a clean way to programmatically check for errors during a parse and handling them after the fact, sometimes one syntax error causes several others (when not recovered in line, for instance), so it can be helpful to group or nest these errors by parent context when displaying output to the user, and you can't know all the errors until the parse is finished, you may want to display errors differently to the user depending on how many and how severe they are, for example, a single error that exited a rule or a few errors all recovered in line might just ask the user to fix these local areas - otherwise, you might have the user edit the entire input, and you need to have all the errors to make this determination. The bottom line is that we can be smarter about reporting and asking users to fix syntax errors if we know the full context in which the errors occurred (including other errors). To do this, I have the following three goals: a full collection of all the errors from a given parse, context information for each error, and severity and recovery information for each error. I have written code to do goal-1 and goal-2, and I'm looking for help on goal-3. I'm also suggesting some small changes to make goal-1 and goal-2 easier for everyone. SUMMARY of my suggestions for a future version of ANTLR: Always populate the "RecognitionException e" parameter of ANTLRErrorListener.syntaxError (including the OffendingToken) so that we can collect these exceptions for batch handling after the parse. While your at it, make sure the e.getMessage() is set to return the value currently in the msg parameter. Add a constructor for RecognitionException that includes OffendingToken. Remove the other parameters (aside from "RecognitionException e") in the method signature of ANTLRErrorListener.syntaxError since they will be extra