Missing variable in Antlr4 parser

I am trying to build a symbol table for a language using Antlr4. I have the following rule in my grammar file.

/* Global String Declaration */
//string_decl : STRING id ASSIGN str SEMICOLON ;
string_decl returns [StrEntry s] : STRING id ASSIGN ex=str SEMICOLON
$s = new StrEntry(); s.addID($id.text); s.addValue($ex.text); ;


I also created a StrEntry class (a dummy implementation)

public class StrEntry


String value;
String id;
String type;


void addID(String x)
id = x;


void addValue(String c)
value = c;





When I compile (javac *.java) I get the following error:

javac *.java

MicroParser.java:382: error: cannot find symbol
((String_declContext)_localctx).s = new StrEntry(); s.addID((((String_declContext)_localctx).id!=null? _input.getText(((String_declContext)_localctx).id.start, ((String_declContext)_localctx).id.stop):null)); s.addValue((((String_declContext)_localctx).ex!=null?_input.getText(((String_declContext)_localctx).ex.start, ((String_declContext)_localctx).ex.stop):null));
^
symbol: variable s
location: class MicroParser


It says variable s of type StrEntry is missing, but I have defined it in my grammar file. I don't think editing it in MicroParser.java file is a good idea as it was generated by Antlr4.

What should I do?

1 Answer
1

$s = new StrEntry(); s.addID($id.text); s.addValue($ex.text)


Here you're using both $s (which will be translated to _localctx.s in the generated Java code) and s (which will remain just s). The latter is the symbol that the compiler can't find because there is no variable with that name defined in that block.

$s

_localctx.s

s

s

In other words, you just need to consistently use $s instead of s and it will work fine.

$s

s

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