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

HelloListener.java

@@ -0,0 +1,39 @@
+// Generated from Hello.g4 by ANTLR 4.13.2
+import org.antlr.v4.runtime.tree.ParseTreeListener;
+
+/**
+ * This interface defines a complete listener for a parse tree produced by
+ * {@link HelloParser}.
+ */
+public interface HelloListener extends ParseTreeListener {
+	/**
+	 * Enter a parse tree produced by {@link HelloParser#greeting}.
+	 * @param ctx the parse tree
+	 */
+	void enterGreeting(HelloParser.GreetingContext ctx);
+	/**
+	 * Exit a parse tree produced by {@link HelloParser#greeting}.
+	 * @param ctx the parse tree
+	 */
+	void exitGreeting(HelloParser.GreetingContext ctx);
+	/**
+	 * Enter a parse tree produced by {@link HelloParser#greet}.
+	 * @param ctx the parse tree
+	 */
+	void enterGreet(HelloParser.GreetContext ctx);
+	/**
+	 * Exit a parse tree produced by {@link HelloParser#greet}.
+	 * @param ctx the parse tree
+	 */
+	void exitGreet(HelloParser.GreetContext ctx);
+	/**
+	 * Enter a parse tree produced by {@link HelloParser#start}.
+	 * @param ctx the parse tree
+	 */
+	void enterStart(HelloParser.StartContext ctx);
+	/**
+	 * Exit a parse tree produced by {@link HelloParser#start}.
+	 * @param ctx the parse tree
+	 */
+	void exitStart(HelloParser.StartContext ctx);
+}