[antlr-interest] How to throw an exception from the lexer to the caller rule

[lemoine at multimania.com]

Hi,
I had specified the testLiterals option to true for the IDENT rule in 
the Lexer to test each token against the literals table.
But when the literal does not match with the lexer IDENT rule, it 
generates an Exception and exits of the lexer.
I want to catch the exception in the caller rule of the parser to 
specify my own error message.

Any help would be greatly apprecied.


Thanks

Hervé



$ cat infile2
GET /NAME=tot?"select name, type from sysdatabases where type='U'" 
HTTP/1.1
$

$ java Main < infile2
unexpected token: NAME
$

If the exception throws to the caller rule (key in the grammar), it 
should be : 

$ java Main < infile2
Unknown option NAME
$


The grammar file is :


class P extends Parser; 

options {
	defaultErrorHandler=false ;
}

{
	String _http_method = null, _http_version = null ;

	public String getToken(String msg) {
	  return msg.substring(18) ;
	}
}

start		: http_method SLASH uri http_version 
        	;

http_method	: g:HTTP_METHOD_GET 
		  { _http_method = g.getText() ; }
		| p:HTTP_METHOD_POST
		  { _http_method = p.getText() ; }
		;
		exception // for HTTP_METHOD
		catch [RecognitionException  e] {
		 String token = getToken(e.getMessage()) ;
		 throw new RecognitionException("HTTP 
method "+token+" not supported");
		}

uri		: commands 
		| queries
		;

http_version	: v1:HTTP_VERSION_10 
		   { _http_version = v1.getText() ; }
		| v2:HTTP_VERSION_11
		   { _http_version = v2.getText() ; }
		;
		exception // for HTTP_VERSION
		catch [RecognitionException e] {
		  String token = getToken(e.getMessage()) ;
		  throw new RecognitionException("Unknown HTTP 
protocol "+token);
		}

commands	: { String val = null ; } 
		  ( 
		    s:STATS
		    { val = s.getText() ; }
		|   d:DSINFOS
		    { val = d.getText() ; }
		|   p:PINFOS
		    { val = p.getText() ; }
		|   h:HELP
		    { val = h.getText() ; }
		  )
		  {
		    System.out.println("command is "+val) ;
		  }
		;
		exception
		catch [RecognitionException e] {
		 String token = getToken(e.getMessage()) ;
		 throw new RecognitionException("Unknown 
command "+token);
		}

queries		: query (SEMI query)*
		;

query		: (optionList QUESTION)? sqlList
		;

optionList	: keypair (COMMA keypair)*
		;

sqlList		: sql (COMMA sql)*
		;

keypair		: { String k = null, v = null ;}

		  k=key EQUALS v=value 
		  { 
		    System.out.println("key="+k) ;
		    System.out.println("value="+v) ; 
		  }
		;

sql		: s:STRING_LITERAL
		  { 
		    System.out.println("sql="+s.getText()) ;
		  }
		;

key returns[String val = null]		

		: pn:PNAME
		  { val = pn.getText() ; }
		| d:DSN
		  { val = d.getText() ; }
		| u:USER
		  { val = u.getText() ; }
		| pw:PWD
		  { val = pw.getText() ; }
		;
		exception
		catch [RecognitionException  e] {
		 String token = getToken(e.getMessage()) ;
		 throw new RecognitionException("Unknown 
option "+token);
		}

value returns[String val = null]

		: s:STRING_LITERAL
		  { val = s.getText() ; }
		| i:IDENT
		  { val = i.getText() ; }
		;


class L extends Lexer; 

options {
	k=2 ;
	charVocabulary = '\3'..'\377' ;
	testLiterals=false ;
}

tokens {
	// HTTP Syntax
	HTTP_METHOD_GET="GET"; HTTP_METHOD_POST="POST";

	// HTTP version
	HTTP_VERSION_10="HTTP/1.0"; HTTP_VERSION_11="HTTP/1.1";

	// Static options keys
	PNAME="PNAME"; DSN="DSN"; USER="USER"; PWD="PWD";

	// Keywords
	STATS="Statistics"; DSINFOS="DataSourcesInfos"; 
	PINFOS="ProfilesInfos"; HELP="Help";
}

//
// string literals
//
STRING_LITERAL	: DQUOTE_LITERAL | SQUOTE_LITERAL
		;
protected
DQUOTE_LITERAL	: '"'!
		  ( '"' '"'!
		  | ~('"'|'\n'|'\r')
		  )*
		  ( '"'!
		  | // nothing
		  )
		;
protected
SQUOTE_LITERAL	: '\''!
		  ( '\'' '\''!
		  | ~('\''|'\n'|'\r')
		  )*
		  ( '\''!
		  | // nothing
		  )
		;
//
// Operators
//
COMMA		: ',' ;
DOT		: '.' ;
QUESTION	: '?' ;
SEMI		: ';' ;
SLASH		: '/' ;
EQUALS		: '=' ;

//
// Whitespace
//
WS		: (' '
		|  '\t'
		|  '\f'
		|  ( "\r\n"
		   | '\r'
		   | '\n'
		   )
		  )
		  { $setType(Token.SKIP) ; }
		;
IDENT
options { testLiterals=true ;}
	
	: 'a'..'z'|'A'..'Z') 'a'..'z'|'A'..'Z'|'0'..'9'|'/'|'.')*
	;


 

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