I should have called out the space after the comment. That's what caused the
problem. "/**/ ". So the input string has 5 characters.
Thanks,
Chris
On Aug 4, 2011, at 7:04 AM, "Sam Harwell" <sharw...@pixelminegames.com> wrote:
> Hi Chris,
>
>
>
> I’m using the released version 3.4.0 of the ANTLR CSharp3 target. I
> copy/pasted the grammar below (aside from renaming it to Preprocessor) and it
> passed the following unit test.
>
>
>
> [TestMethod]
>
> public void TestEmptyComment()
>
> {
>
> string inputText = "/**/";
>
> var input = new ANTLRStringStream(inputText);
>
> var lexer = new PreprocessorLexer(input);
>
> var tokenStream = new CommonTokenStream(lexer);
>
> tokenStream.Fill();
>
>
>
> List<IToken> tokens = tokenStream.GetTokens();
>
> Assert.AreEqual(2, tokens.Count);
>
> Assert.AreEqual(PreprocessorLexer.DELIMITED_COMMENT, tokens[0].Type);
>
> Assert.AreEqual(inputText, tokens[0].Text);
>
> Assert.AreEqual(PreprocessorLexer.EOF, tokens[1].Type);
>
> }
>
>
>
> Sam
>
>
>
> From: chris king [mailto:kingce...@gmail.com]
> Sent: Thursday, August 04, 2011 3:48 AM
> To: Sam Harwell; antlr-interest@antlr.org
> Subject: Re: Have I found an Antlr CSharp3 lexer bug if...
>
>
>
> Sam, while trying build my pre-processor with a mixed parser/lexer I ran
> across what I think might be a bug. I reduced the repro below. I expected the
> program below to accept "/**/ " but instead fails because the lexer
> prediction enters PP_SKIPPED_CHARACTERS. That rule has a gated semantic
> predicate which is always false. I expected a lexer rule with a gated
> semantic predicate which is always false to never be matched. If I comment
> out the PP_SKIPPED_CHARACTERS rule then it does match "/**/ ". So the
> inclusion of that rule is cause the problem. Let me know if you think this is
> a bug and if you can repro.
>
>
>
> Thanks,
> Chris
>
>
>
> grammar Bug;
>
>
>
> options {
>
> language=CSharp3;
>
> output=AST;
>
> }
>
>
>
> public start
>
> : DELIMITED_COMMENT !EOF
>
> ;
>
>
>
> PP_SKIPPED_CHARACTERS
>
> : { false }? => ~(F_NEW_LINE_CHARACTER | F_PP_POUND_SIGN) F_INPUT_CHARACTER*
>
> ;
>
>
>
> DELIMITED_COMMENT
>
> : { true }? => '/*' .* '*/'
>
> ;
>
>
>
> WHITESPACE
>
> : F_WHITESPACE {skip();}
>
> ;
>
>
>
> fragment F_WHITESPACE
>
> : (' ' | '\t' | '\v' | '\f')+
>
> ;
>
>
>
> fragment F_NEW_LINE_CHARACTER
>
> : '\r'
>
> | '\n'
>
> ;
>
>
>
> fragment F_PP_POUND_SIGN
>
> : '#'
>
> ;
>
>
>
> fragment F_INPUT_CHARACTER
>
> : ~F_NEW_LINE_CHARACTER
>
> ;
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