import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.Token;
import java.io.BufferedReader;
import java.io.FileReader;

public class ANTLRDemo {

    public static void main(String[] args) throws Exception {
        // Read in input from the source code file
        String currentLine = null;
        String sourceCode = "";
        BufferedReader readerIn = new BufferedReader(new FileReader("HelloWorld.java"));

        while ((currentLine = readerIn.readLine()) != null) {
            sourceCode += currentLine;
        }

        // Lexical Analysis - generate the tokens for the compiler
        CharStream in = new ANTLRInputStream(sourceCode);
        JavaLexer lexer = new JavaLexer(in);
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        tokens.fill();

        // Syntax Analysis - Parse the tokens into a parse tree
        JavaParser parser = new JavaParser(tokens);
        System.out.println(parser.compilationUnit().toStringTree());
    }
}