ANTLR4 - keep getting a mismatched input error

Question

I just started working with Antlr 4. I tried to write a grammar rules for a simple program, but I'm having a difficult time getting it to work.

I am trying to parse a sequence of lines that look like

$int a;
$string b;
$int num;

However, I keep getting the following error. "line 1:5 mismatched input 'a' expecting IDENTIFIER"

I have tried

• Getting a small repro
• Checking if making something a "fragment" is affecting things

Unfortunately, I am having a difficult time figuring out why this is failing or what exactly to search for to find out more about this. My grammar rules are given below

SEPARATION : [ \t\r\n\u000C]+;

fragment 
STARTING_CHARACTER : [a-zA-Z];
fragment 
CHARACTER : [a-zA-Z0-9_];
TERMINATE_CHARACTER : ';';

fragment
TYPE_OR_VAR_IDENTIFIER : STARTING_CHARACTER CHARACTER*;
NAMESPACED_TYPENAME : TYPE_OR_VAR_IDENTIFIER;
IDENTIFIER : TYPE_OR_VAR_IDENTIFIER;

type : '$' NAMESPACED_TYPENAME;

declaration_statement : SEPARATION? type SEPARATION IDENTIFIER SEPARATION? TERMINATE_CHARACTER;

statement : declaration_statement;

Any help is appreciated!

Answer 1

After some additional searching, finally stumbled on to a solution. Looks like this was a similar problem as seen here

Mismatched input error in simple antlr4 grammar