Hi Justin, The exception does get thrown, but is handled in Lexer.NextToken() by tossing out a character and continuing. There are many ways to deal with this situation ranging from overriding NextToken in your lexer to creating an ANYCHAR rule at the very end that allows the incorrect input characters to pass on to the parser for handling there.
ANYCHAR : . ; Sam -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Justin Holewinski Sent: Tuesday, April 19, 2011 11:49 AM To: [email protected] Subject: [antlr-interest] [C#] Lexer Not Throwing Errors I'm using the C# 3 port of Antlr (target and code generator) and I'm experiencing a lack of lexer errors being generated. As a concrete example, consider the following grammar: grammar CSTest; public compilation_unit : IDENTIFIER* EOF ; IDENTIFIER : (ID_PART) (ID_PART_OR_NUMBER)* ; fragment ID_PART : ('a'..'z' | 'A'..'Z' | '_') ; fragment ID_PART_OR_NUMBER : ID_PART | '0'..'9' ; WS : (' '|'\r'|'\t'|'\n') { /*Skip();*/ $channel=Hidden; } ; The only production in this grammar should allow for an arbitrary sequence of identifiers, and it does. However, it also accepts ALL input, including binary files and anything else I pipe into it. Is the default in the C# target to silently ignore any lexing errors? In my driver program, I am not seeing any throw exceptions when I call the compilation_unit rule. using System; using System.IO; using Antlr.Runtime; namespace CSTest { public class Program { public static void Main(string[] args) { string filename; filename = args[0]; if(!Path.IsPathRooted(filename)) { filename = Path.Combine(Environment.CurrentDirectory, filename); } ICharStream input = new ANTLRFileStream(filename); CSTestLexer lexer = new CSTestLexer(input); CommonTokenStream tokens = new CommonTokenStream(lexer); CSTestParser parser = new CSTestParser(tokens); try { parser.compilation_unit(); } catch(RecognitionException re) { Console.Out.WriteLine("EXCEPTION"); Console.Out.WriteLine(re.StackTrace); } } } } -- Thanks, Justin Holewinski 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 -- You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en.
