Antlr4 Parse error message not as expected

[CzyerChen]

Now, I want to make a rule to match a(b(c,d)), and d is between (max,min）caseSensitive. So I made a try below

Lexer.g4:

lexer grammar DLexer;

// Keywords
GENERAL_LABEL_NAME:       '_';

// Constructors symbols
DOT:         '.';
COMMA:       ',';
L_PAREN:     '(';
R_PAREN:     ')';
L_BRACKET:   '[';
R_BRACKET:   ']';
L_BRACE:     '{';
R_BRACE:     '}';
EQ:          '=';

// Scalar Binary operators
SUB:         '-';
ADD:         '+';
MUL:         '*';
DIV:         '/';
MOD:         '%';
DEQ:         '==';
NEQ:         '!=';
LTE:         '<=';
LT:          '<';
GTE:         '>=';
GT:          '>';

MAX:         'max';
MIN:         'min';

A: 'a'  ;
B: 'b'   ;

// Literals
INTEGER: Digit+;
DECIMAL: Digit+ DOT Digit+;
NAME_STRING: NameLetter+;
VALUE_STRING: '\'' .*? '\'' | '"' .*? '"';

// Fragments
fragment Digit: [0-9];
fragment NameLetter: [a-zA-Z0-9_];

WS : [ \t\r\n]+ -> skip;

Parser.g4:

parser grammar DParser;

options { tokenVocab = DLexer; }

root: expression;

expression
    : expressionNode                   # exprNode
    | L_PAREN expression R_PAREN       # parensOp
    | expression plusSub  expression    # plusSubOP
    | a L_PAREN expression COMMA aFunc R_PAREN #aOp
    ;

expressionNode:  metric| scalar;

metricName:      NAME_STRING;
metric:   metricName | metricName L_BRACE label? R_BRACE;

labelName:       GENERAL_LABEL_NAME;
labelValue:      VALUE_STRING;
label:           labelName EQ labelValue;

scalar:   INTEGER | DECIMAL;

plusSub: ADD | SUB;

a: A;

b: B;

aFunc:
    MAX | MIN;

And I did the test later:

public class ExpressionValidator {
    public static void main(String[] args) throws Exception {
         String input = "a(uptime,sum)";
        CharStream charStream = CharStreams.fromString(input);
        MQELexer lexer = new MQELexer(charStream);
        lexer.addErrorListener(new ParseErrorListener());
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        MQEParser parser = new MQEParser(tokens);
        parser.addErrorListener(new ParseErrorListener());
       try {
            ParseTree tree = parser.expression();
            System.out.println("Expression is valid and successfully parsed.");
            System.out.println(tree.toStringTree(parser));
        } catch (ParseCancellationException e) {
            e.printStackTrace();
        }
    }

I got the ParseCancellationException

line 1:9 mismatched input 'SUM' expecting {',', '-', '+'}
org.antlr.v4.runtime.misc.ParseCancellationException: line 1:9 mismatched input 'SUM' expecting {',', '-', '+'}
	at com.example.antlr4demo.util.ParseErrorListener.syntaxError(ParseErrorListener.java:55)
	at org.antlr.v4.runtime.ProxyErrorListener.syntaxError(ProxyErrorListener.java:41)
	at org.antlr.v4.runtime.Parser.notifyErrorListeners(Parser.java:544)
	at org.antlr.v4.runtime.DefaultErrorStrategy.reportInputMismatch(DefaultErrorStrategy.java:327)
	at org.antlr.v4.runtime.DefaultErrorStrategy.reportError(DefaultErrorStrategy.java:139)
	at com.example.antlr4demo.grammer.demo.DParser.aFunc(DParser.java:841)
	at com.example.antlr4demo.grammer.demo.DParser.expression(DParser.java:290)
	at com.example.antlr4demo.grammer.demo.DParser.expression(DParser.java:234)
	at com.example.antlr4demo.util.DemoExpressionValidator.main(DemoExpressionValidator.java:42)

The error message not about {'max','min'} but about {'+'.'-'}

I found that there is a conflict between the two expressions expression plusSub expression and a L_PAREN expression COMMA aFunc R_PAREN. It will firstly match the expression plusSub expression, but the input string nothing to do with '+' or '-'.

If I remove expression plusSub expression, the error message will be expecting {'max','min'} as expected.

How can I compatible with both checks?