can an element contain attribute as parsed by parser generated by ANTLR? if so, how?

Question

I am following this tutorial and successfully replicated its behavior except that I am using Antlr 4.7 instead of the 4.5 that the tutorial was using.

I am trying to bui

Answer 1

Situation on October 24. 2017 at 19:00 UTC+1.

Your grammar works perfectly. I made a full test in Java.

File Expense.g4 :

grammar Expense;

payments
@init {System.out.println("Expense last update 1853");}
    : (payment NL)*
    ;

payment
    : PAY receiver amount=NUMBER
      {System.out.println("Payement found " + $amount.text + " to " + $receiver.text);}
    ;

receiver
    : surname=ID (lastname=ID)?
    ; 

PAY    : 'pay' ;
NUMBER : ([0-9]+(','[0-9]+)*)('.'[0-9]*)? ;
ID     : [a-zA-Z0-9_]+ ;
NL     : '\n' | '\r\n' ;  
WS     : [\t ]+ -> channel(HIDDEN) ; // keep the spaces (witout spaces ==> paydeltaco98)

File ExpenseMyListener.java :

public class ExpenseMyListener extends ExpenseBaseListener {
    ExpenseParser parser;
    public ExpenseMyListener(ExpenseParser parser) { this.parser = parser; }

    public void exitPayments(ExpenseParser.PaymentsContext ctx) {
        System.out.println(">>> in ExpenseMyListener for paymentsss");
        System.out.println(">>> there are " + ctx.payment().size() + " elements in the list of payments");
        for (int i = 0; i < ctx.payment().size(); i++) {
            System.out.println(ctx.payment(i).getText());
        }
    }

    public void exitPayment(ExpenseParser.PaymentContext ctx) {
        System.out.println(">>> in ExpenseMyListener for payment");
        System.out.println(parser.getTokenStream().getText(ctx));
    }
}

File test_expense.java :

import org.antlr.v4.runtime.ANTLRFileStream;
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.tree.*;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.IOException;

public class test_expense {
    public static void main(String[] args) throws IOException {
        ANTLRInputStream input = new ANTLRFileStream(args[0]);
        ExpenseLexer lexer = new ExpenseLexer(input);
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        ExpenseParser parser = new ExpenseParser(tokens);
        ParseTree tree = parser.payments();
        System.out.println("---parsing ended");
        ParseTreeWalker walker = new ParseTreeWalker();
        ExpenseMyListener my_listener = new ExpenseMyListener(parser);
        System.out.println(">>>> about to walk");
        walker.walk(my_listener, tree);
    }
}

Input file top.text :

pay Acme Corp 123,456
pay Banana Inc 456789.00
pay charlie pte 123,456.89
pay delta co 98

Execution :

$ export CLASSPATH=".:/usr/local/lib/antlr-4.6-complete.jar"
$ alias
alias a4='java -jar /usr/local/lib/antlr-4.6-complete.jar'
alias grun='java org.antlr.v4.gui.TestRig'
$ a4 Expense.g4 
$ javac Ex*.java
$ javac test_expense.java 
$ grun Expense payments -tokens -diagnostics top.text
[@0,0:2='pay',<'pay'>,1:0]
[@1,3:3=' ',,channel=1,1:3]
[@2,4:7='Acme',,1:4]
[@3,8:8=' ',,channel=1,1:8]
[@4,9:12='Corp',,1:9]
...
[@32,90:89='',,5:0]
Expense last update 1853
Payement found 123,456 to Acme Corp
Payement found 456789.00 to Banana Inc
Payement found 123,456.89 to charlie pte
Payement found 98 to delta co

$ java test_expense top.text 
Expense last update 1853
Payement found 123,456 to Acme Corp
Payement found 456789.00 to Banana Inc
Payement found 123,456.89 to charlie pte
Payement found 98 to delta co
---parsing ended
>>>> about to walk
>>> in ExpenseMyListener for payment
pay Acme Corp 123,456
>>> in ExpenseMyListener for payment
pay Banana Inc 456789.00
>>> in ExpenseMyListener for payment
pay charlie pte 123,456.89
>>> in ExpenseMyListener for payment
pay delta co 98
>>> in ExpenseMyListener for paymentsss
>>> there are 4 elements in the list of payments
payAcmeCorp123,456
payBananaInc456789.00
paycharliepte123,456.89
paydeltaco98