fixes impossibl#608

- when a $1 or $$foo$$ is within () expression, like a function
  invocation, parse the $ as plain grammar piece
- add a test for this situation which does not parse otherwise
  and throws ParseException

driver/src/main/java/com/impossibl/postgres/jdbc/SQLText.java

@@ -330,6 +330,12 @@ private static int consumeDollar(final String sql, final int start, final Compos
       }
     } while (++ndx < sql.length());
 
+    // Treat as a grammar piece of only one char if within paren expression
+    if (parent instanceof ParenGroupNode) {
+        parent.add(new GrammarPiece(sql.substring(start, start + 1), start));
+        return start + 1;
+    }
+
     // Just treat as a grammar piece
     parent.add(new GrammarPiece(sql.substring(start, ndx), start));
     return ndx;

driver/src/test/java/com/impossibl/postgres/jdbc/SQLTextTests.java

@@ -97,6 +97,30 @@ public class SQLTextTests {
       "--\n--",
       "--\n--",
     },
+    new String[] {
+      "PREPARE test_plan AS SELECT hashtext($1)",
+      "PREPARE test_plan AS SELECT hashtext($1)",
+    },
+    new String[] {
+      "PREPARE test_plan AS SELECT hashtext($$foo$$)",
+      "PREPARE test_plan AS SELECT hashtext($$foo$$)",
+    },
+    new String[] {
+      "PREPARE test_plan AS SELECT hashtext($$fo;o$$)",
+      "PREPARE test_plan AS SELECT hashtext($$fo;o$$)",
+    },
+    new String[] {
+      "select * from flatten('{\"a\":1,\"b\":2}', $ as root) as f",
+      "select * from flatten('{\"a\":1,\"b\":2}', $ as root) as f",
+    },
+    new String[] {
+      "call help ( $$ { me } $$ )",
+      "call help ( $$ { me } $$ )",
+    },
+    new String[] {
+      "call help ( $delim$ { me } $delim$ )",
+      "call help ( $delim$ { me } $delim$ )",
+    },
   };
 
   /**