GraphQL\Language\Visitor::visitWithTypeInfo PHP Method

    static function visitWithTypeInfo(TypeInfo $typeInfo, $visitor)
    {
        return ['enter' => function ($node) use($typeInfo, $visitor) {
            $typeInfo->enter($node);
            $fn = self::getVisitFn($visitor, $node->kind, false);
            if ($fn) {
                $result = call_user_func_array($fn, func_get_args());
                if ($result) {
                    $typeInfo->leave($node);
                    if ($result instanceof Node) {
                        $typeInfo->enter($result);
                    }
                }
                return $result;
            }
            return null;
        }, 'leave' => function ($node) use($typeInfo, $visitor) {
            $fn = self::getVisitFn($visitor, $node->kind, true);
            $result = $fn ? call_user_func_array($fn, func_get_args()) : null;
            $typeInfo->leave($node);
            return $result;
        }];
    }

 /**
  * @it maintains type info during edit
  */
 public function testMaintainsTypeInfoDuringEdit()
 {
     $visited = [];
     $typeInfo = new TypeInfo(TestCase::getDefaultSchema());
     $ast = Parser::parse('{ human(id: 4) { name, pets }, alien }');
     $editedAst = Visitor::visit($ast, Visitor::visitWithTypeInfo($typeInfo, ['enter' => function ($node) use($typeInfo, &$visited) {
         $parentType = $typeInfo->getParentType();
         $type = $typeInfo->getType();
         $inputType = $typeInfo->getInputType();
         $visited[] = ['enter', $node->kind, $node->kind === 'Name' ? $node->value : null, $parentType ? (string) $parentType : null, $type ? (string) $type : null, $inputType ? (string) $inputType : null];
         // Make a query valid by adding missing selection sets.
         if ($node->kind === 'Field' && !$node->selectionSet && Type::isCompositeType(Type::getNamedType($type))) {
             return new FieldNode(['alias' => $node->alias, 'name' => $node->name, 'arguments' => $node->arguments, 'directives' => $node->directives, 'selectionSet' => new SelectionSetNode(['kind' => 'SelectionSet', 'selections' => [new FieldNode(['name' => new NameNode(['value' => '__typename'])])]])]);
         }
     }, 'leave' => function ($node) use($typeInfo, &$visited) {
         $parentType = $typeInfo->getParentType();
         $type = $typeInfo->getType();
         $inputType = $typeInfo->getInputType();
         $visited[] = ['leave', $node->kind, $node->kind === 'Name' ? $node->value : null, $parentType ? (string) $parentType : null, $type ? (string) $type : null, $inputType ? (string) $inputType : null];
     }]));
     $this->assertEquals(Printer::doPrint(Parser::parse('{ human(id: 4) { name, pets }, alien }')), Printer::doPrint($ast));
     $this->assertEquals(Printer::doPrint(Parser::parse('{ human(id: 4) { name, pets { __typename } }, alien { __typename } }')), Printer::doPrint($editedAst));
     $this->assertEquals([['enter', 'Document', null, null, null, null], ['enter', 'OperationDefinition', null, null, 'QueryRoot', null], ['enter', 'SelectionSet', null, 'QueryRoot', 'QueryRoot', null], ['enter', 'Field', null, 'QueryRoot', 'Human', null], ['enter', 'Name', 'human', 'QueryRoot', 'Human', null], ['leave', 'Name', 'human', 'QueryRoot', 'Human', null], ['enter', 'Argument', null, 'QueryRoot', 'Human', 'ID'], ['enter', 'Name', 'id', 'QueryRoot', 'Human', 'ID'], ['leave', 'Name', 'id', 'QueryRoot', 'Human', 'ID'], ['enter', 'IntValue', null, 'QueryRoot', 'Human', 'ID'], ['leave', 'IntValue', null, 'QueryRoot', 'Human', 'ID'], ['leave', 'Argument', null, 'QueryRoot', 'Human', 'ID'], ['enter', 'SelectionSet', null, 'Human', 'Human', null], ['enter', 'Field', null, 'Human', 'String', null], ['enter', 'Name', 'name', 'Human', 'String', null], ['leave', 'Name', 'name', 'Human', 'String', null], ['leave', 'Field', null, 'Human', 'String', null], ['enter', 'Field', null, 'Human', '[Pet]', null], ['enter', 'Name', 'pets', 'Human', '[Pet]', null], ['leave', 'Name', 'pets', 'Human', '[Pet]', null], ['enter', 'SelectionSet', null, 'Pet', '[Pet]', null], ['enter', 'Field', null, 'Pet', 'String!', null], ['enter', 'Name', '__typename', 'Pet', 'String!', null], ['leave', 'Name', '__typename', 'Pet', 'String!', null], ['leave', 'Field', null, 'Pet', 'String!', null], ['leave', 'SelectionSet', null, 'Pet', '[Pet]', null], ['leave', 'Field', null, 'Human', '[Pet]', null], ['leave', 'SelectionSet', null, 'Human', 'Human', null], ['leave', 'Field', null, 'QueryRoot', 'Human', null], ['enter', 'Field', null, 'QueryRoot', 'Alien', null], ['enter', 'Name', 'alien', 'QueryRoot', 'Alien', null], ['leave', 'Name', 'alien', 'QueryRoot', 'Alien', null], ['enter', 'SelectionSet', null, 'Alien', 'Alien', null], ['enter', 'Field', null, 'Alien', 'String!', null], ['enter', 'Name', '__typename', 'Alien', 'String!', null], ['leave', 'Name', '__typename', 'Alien', 'String!', null], ['leave', 'Field', null, 'Alien', 'String!', null], ['leave', 'SelectionSet', null, 'Alien', 'Alien', null], ['leave', 'Field', null, 'QueryRoot', 'Alien', null], ['leave', 'SelectionSet', null, 'QueryRoot', 'QueryRoot', null], ['leave', 'OperationDefinition', null, null, 'QueryRoot', null], ['leave', 'Document', null, null, null, null]], $visited);
 }