Add base parser specification

assignment.jj

@@ -0,0 +1,42 @@
+PARSER_BEGIN(Assignment)
+    class Assignment {
+        public static void main(String[] args) throws ParseException, TokenMgrError
+        {
+            try {
+                Assignment parser = new Assignment(System.in);
+                parser.Start();
+                System.out.println("PASS");
+            } catch (ParseException e) {
+                System.out.println("FAIL");
+                System.err.println(e.currentToken.beginLine);
+            }
+        }
+    }
+PARSER_END(Assignment)
+
+TOKEN : { <LEFT_PAREN: "(">}
+TOKEN : { <RIGHT_PAREN: ")">}
+TOKEN : { <NEWLINE: "\n">}
+TOKEN : { <ANY: (~[])>}
+
+void Start() : {}
+{
+    (ValidLine()<NEWLINE>)+<EOF>
+}
+
+// Single well-parenthesized string
+void ValidLine() : {}
+{
+    <LEFT_PAREN>Parens()<RIGHT_PAREN>Parens()
+}
+
+// Recursion to allow arbitrary length of parentheses
+void Parens() : {}
+{
+    <LEFT_PAREN>Parens()<RIGHT_PAREN>Parens() | Epsilon()
+}
+
+void Epsilon() : {}
+{
+    {} // Have to have some kind of body apparently
+}