[antlr-interest] Pattern for returning errors from ANTLR in data structures, not STDERR

[Terence Parr]

Let me be more specific.

In the v4 prerelease stuff, Tool.java has

// http://antlr.org/depot/antlr4/main/tool/src/org/antlr/v4/Tool.java
	public void error(Message msg) {
		if ( listeners.size()==0 ) {
			defaultListener.error(msg);
			return;
		}
		for (ANTLRToolListener l : listeners) l.error(msg);
	}

using

http://antlr.org/depot/antlr4/main/tool/src/org/antlr/v4/tool/ANTLRToolListener.java

then in

http://antlr.org/depot/antlr4/main/tool/src/org/antlr/v4/parse/ToolANTLRParser.java

I do:

	public void displayRecognitionError(String[] tokenNames,
										RecognitionException e)
	{
		String msg = getParserErrorMessage(this, e);
		if ( paraphrases.size()>0 ) {
			String paraphrase = (String)paraphrases.peek();
			msg = msg+" while "+paraphrase;
		}
	//	List stack = getRuleInvocationStack(e, this.getClass().getName());
	//	msg += ", rule stack = "+stack;
		tool.errMgr.syntaxError(ErrorType.SYNTAX_ERROR, getSourceName(), e.token, e, msg);
	}

which forces all msgs from antlr to shunt to Tool.error(), which announces to listeners.

For testing, i have unit tests use this

http://antlr.org/depot/antlr4/main/tool/test/org/antlr/v4/test/ErrorQueue.java

as a listener to the tool like so:

			Tool antlr = newTool(optionsA);
			antlr.addListener(equeue);

Ter

On Nov 30, 2010, at 5:20 PM, Terence Parr wrote:

> Check ANTLRToolListener in antlr source or whatever. it has a similar problem to solve.
> Ter
> On Nov 30, 2010, at 5:13 PM, Arthur Goldberg wrote:
> 
>> Hello All
>> 
>> My ANTLR parser is embedded in other code. I've decided that reporting 
>> errors out of the parser would be better handled as a list of errors, 
>> not exceptions, so that the parse is allowed to recover from errors and 
>> complete, if possible.
>> Does anyone have a working pattern for returning errors from ANTLR in a 
>> list, not STDERR?
>> In more detail, I'd run it in two modes:
>> 1) testing: call some rule other than the root
>> In this case, I will let the rule report an error via an exception.
>> 
>> 2) production: call the root rule
>> In this case, a newReportError() in
>> 
>>    catch (RecognitionException re) {
>>        newReportError(re);
>>        recover(input,re);
>>    }
>> 
>> would catch exceptions thrown by other rules, and store them in a list. 
>> When the root rule returns, it returns the list of errors, along with 
>> the results of the parse.
>> 
>> If someone can help me with this, I'll make it worth your while. I'm 
>> running out of time for messing with ANTLR.
>> 
>> Thanks
>> Arthur
>> 
>> 
>> 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