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

@@ -313,6 +313,12 @@ private static int consumeParens(final String sql, final int start, final Deque<
   }
 
   private static int consumeDollar(final String sql, final int start, final CompositeNode parent) throws ParseException {
+
+    if (parent instanceof ParenGroupNode) {
+      parent.add(new GrammarPiece(sql.substring(start, start + 1), start));
+      return start + 1;
+    }
+
     int ndx = start;
     do {
       if (lookAhead(sql, ndx) == '$') {

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

@@ -97,6 +97,22 @@ 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",
+    },
   };
 
   /**