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I previously posted about my first attempt at using ANTLR when I was having issues with left recursion.

Now that I have resolved those issues, I am getting the following error when I try to use org.antlr.v4.Tool to generate the code:

error(99): C:test.g4::: grammar 'test' has no rules

What are the possible reasons for this error? Using ANTLRWorks I can certainly see rules in the Parse Tree so why can't it see them? Is it because it cannot find a suitable START rule?

Felix Bembrick
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  • Well, if you resolved your earlier problem, could you either post the answer/solution there, or remove the question? – Bart Kiers Jun 13 '13 at 06:19
  • Can you post the grammar, and post exactly how you're trying to generate the parser/lexer classes using the `Tool`? – Bart Kiers Jun 13 '13 at 06:20
  • You may have a syntax error in the file which is causing ANTLR to stop parsing. Can you post your grammar up through (and including) the first rule? – Sam Harwell Jun 28 '13 at 17:40

7 Answers7

10

I think Antlr expects the first rule name to be in small case. I was getting the same error with my grammar

grammar ee;
Condition : LogicalExpression ;
LogicalExpression : BooleanLiteral ; 
BooleanLiteral :  True ;
True : 'true' ;

By changing the first production rule in the grammar to lower case it solved the issue i.e. the below grammar worked for me.

grammar ee;
condition : LogicalExpression ;
LogicalExpression : BooleanLiteral ; 
BooleanLiteral :  True ;
True : 'true' ;

Note: It is my personal interpretation, I couldn't find this reasoning in the online documentation.

Edit: The production rules should begin with lower case letters as specified in the latest docs [1]

[1] https://github.com/antlr/antlr4/blob/master/doc/lexicon.md#identifiers

vdua
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    I met the same issue. I think the names of grammar rules (aka the non-terminal rules) must be in all lower-case. – smwikipedia Dec 31 '16 at 07:02
2

I'm not sure if you've found the solution for this, but I had the same problem and fixed it by changing my start symbol to 'prog'. So for example, the first two lines of your .g4 file would be: 

    grammar test;
    prog : <...> ;

Where <...> will be your first derivation.

Markoorn
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1

I just got that error as well (antlworks 2.1). switching from RULE : THIS | THAT ; to rule : this | that ; for parser rules (i.e. from uppercase to lowercase) solved the problem!

EDIT The above correction holds only for RULE , what follows after the : can be any combination of lexer/parser rules

Dio
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0

The most likely cause is just what the error message suggests. And the most likely reason for that is that you have not saved your grammar to the file--or if you're using ANTLRWorks2--ANTLRWorks hasn't saved your work to the file. I have no idea why ANTLRWorks doesn't save reliably.

Roy
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  • With your remark *"I have no idea why ANTLRWorks doesn't save reliably"*, you're assuming it's ANTLWorks that is malfunctioning and not the OP. I bet it's the other way around. – Bart Kiers Jun 28 '13 at 17:38
  • I said ANTLRWorks doesn't save reliably because it does it to me, which is how I knew a likely answer to the OP's question. – Roy Jun 29 '13 at 07:09
  • Your reasoning is incorrect. It _is_ **an** answer, and had I seen it when I first encountered error(99) it would have been _the_ answer. Given that the file save problem is easily reproducible in ANTLRWorks2 it is even--as I said--a likely answer. BTW, only I have mentioned ANTLRWorks2. Are we even talking about the same software? Clarify. – Roy Jun 30 '13 at 08:02
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I also got the same error but could not fix it. I downloaded antlrworks-1.4.jar and it's working perfectly.

Download >> antlrworks-1.4.jar

Cjo
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0

Changing the first rule to start with a lower case character worked for me.

Chet
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I had the same problem, and this means that your grammar has no Syntactic rules. So in order to avoid this error, you need to write at least one Syntactic rule.

aicha ouadah
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