Question

I have the following language i wish to parse using antlr 1.2.2.

TEST <name>
{
   <param_name> = <param value>;
}

while
<…> – means user value, not part of the language keywords

for example

TEST myTest
{
   my_param = 1.0;
}

the value can be an integer, a real or a quated string
my_param = 1.0;, my_param = 1; and my_param = "myStringValue"; are all valid inputs.

here is the grammer for this parsing.

parse_test  : TESTKEYWORD TEST_NAME '{' param_value_def '}';
param_value_def : ID EQUALS param_value ';';
param_value : REAL|INTEGER|QUOTED_STRING;


TESTKEYWORD : 'TEST';

QUOTED_STRING   :  '"' ~('"')* '"';

INTEGER     :  MINUS? DIGIT DIGIT*

REAL        :  INTEGER '.' DIGIT DIGIT*;

EQUALS      : '=';

fragment
MINUS       : '-';

fragment
DIGIT       : '0'..'9';

when i feed the sample input to the antlr interpreter, i get a `MismatchedTokenException’ related to the param_value rule.

can you help me cipher the error message and what i am doing wrong?

thanks

Answer 1

Although ANTLRWorks is not a tool well written, you can use its debugger to see which token in the input leads to this exception, and then you can see which rules need to be revised (since you did not post the full grammar).

http://www.antlr.org/works/index.html