Add ANTLR grammar for greetings and farewells with corresponding parser and listener implementations

HelloBaseListener.java

@@ -0,0 +1,75 @@
+// Generated from Hello.g4 by ANTLR 4.13.2
+
+import org.antlr.v4.runtime.ParserRuleContext;
+import org.antlr.v4.runtime.tree.ErrorNode;
+import org.antlr.v4.runtime.tree.TerminalNode;
+
+/**
+ * This class provides an empty implementation of {@link HelloListener},
+ * which can be extended to create a listener which only needs to handle a subset
+ * of the available methods.
+ */
+@SuppressWarnings("CheckReturnValue")
+public class HelloBaseListener implements HelloListener {
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void enterGreeting(HelloParser.GreetingContext ctx) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void exitGreeting(HelloParser.GreetingContext ctx) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void enterGreet(HelloParser.GreetContext ctx) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void exitGreet(HelloParser.GreetContext ctx) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void enterStart(HelloParser.StartContext ctx) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void exitStart(HelloParser.StartContext ctx) { }
+
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void enterEveryRule(ParserRuleContext ctx) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void exitEveryRule(ParserRuleContext ctx) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void visitTerminal(TerminalNode node) { }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation does nothing.</p>
+	 */
+	@Override public void visitErrorNode(ErrorNode node) { }
+}