parens for complex stmts

Author: pyramation

__fixtures__/generated/generated.json

@@ -21097,6 +21097,7 @@
   "misc/issues-11.sql": "COMMENT ON COLUMN \"foo\".\"whatever\" IS $$\nSomething blah, this data may have chars like '\\n' and '\\r' in it.\n$$",
   "misc/issues-12.sql": "SELECT * from foo.bar.baz",
   "misc/issues-13.sql": "CREATE AGGREGATE json_agg_strict(anyelement)(\n  SFUNC = json_agg_strict_sfunc,\n  STYPE = jsonb,\n  FINALFUNC = json_agg_strict_finalfunc,\n  INITCOND = '[]'\n)",
+  "misc/issues-14.sql": "SELECT (1 IS NOT NULL) IS DISTINCT FROM (2 IS NOT NULL)",
   "misc/inflection-1.sql": "CREATE SCHEMA inflection",
   "misc/inflection-2.sql": "GRANT USAGE ON SCHEMA inflection TO PUBLIC",
   "misc/inflection-3.sql": "ALTER DEFAULT PRIVILEGES IN SCHEMA inflection \n GRANT EXECUTE ON FUNCTIONS  TO PUBLIC",

__fixtures__/kitchen-sink/misc/issues.sql

@@ -64,4 +64,7 @@ CREATE AGGREGATE json_agg_strict(anyelement)(
   STYPE = jsonb,
   FINALFUNC = json_agg_strict_finalfunc,
   INITCOND = '[]'
-);
+);
+
+-- https://github.com/launchql/pgsql-parser/issues/62
+SELECT (1 IS NOT NULL) IS DISTINCT FROM (2 IS NOT NULL);

packages/deparser/__tests__/kitchen-sink/misc-issues.test.ts

@@ -16,6 +16,7 @@ it('misc-issues', async () => {
   "misc/issues-10.sql",
   "misc/issues-11.sql",
   "misc/issues-12.sql",
-  "misc/issues-13.sql"
+  "misc/issues-13.sql",
+  "misc/issues-14.sql"
 ]);
 });

packages/deparser/src/deparser.ts

@@ -438,18 +438,42 @@ export class Deparser implements DeparserVisitor {
           'ALL',
           this.formatter.parens(this.visit(rexpr, context))
         ]);
-      case 'AEXPR_DISTINCT':
+      case 'AEXPR_DISTINCT': {
+        let leftExpr = this.visit(lexpr, context);
+        let rightExpr = this.visit(rexpr, context);
+        
+        // Add parentheses for complex expressions
+        if (lexpr && this.isComplexExpression(lexpr)) {
+          leftExpr = this.formatter.parens(leftExpr);
+        }
+        if (rexpr && this.isComplexExpression(rexpr)) {
+          rightExpr = this.formatter.parens(rightExpr);
+        }
+        
         return this.formatter.format([
-          this.visit(lexpr, context),
+          leftExpr,
           'IS DISTINCT FROM',
-          this.visit(rexpr, context)
+          rightExpr
         ]);
-      case 'AEXPR_NOT_DISTINCT':
+      }
+      case 'AEXPR_NOT_DISTINCT': {
+        let leftExpr = this.visit(lexpr, context);
+        let rightExpr = this.visit(rexpr, context);
+        
+        // Add parentheses for complex expressions
+        if (lexpr && this.isComplexExpression(lexpr)) {
+          leftExpr = this.formatter.parens(leftExpr);
+        }
+        if (rexpr && this.isComplexExpression(rexpr)) {
+          rightExpr = this.formatter.parens(rightExpr);
+        }
+        
         return this.formatter.format([
-          this.visit(lexpr, context),
+          leftExpr,
           'IS NOT DISTINCT FROM',
-          this.visit(rexpr, context)
+          rightExpr
         ]);
+      }
       case 'AEXPR_NULLIF':
         return this.formatter.format([
           'NULLIF',