GraphQL\Validator\Rules\NoUnusedVariables::__invoke PHP Метод

    public function __invoke(ValidationContext $context)
    {
        $this->variableDefs = [];
        return [NodeKind::OPERATION_DEFINITION => ['enter' => function () {
            $this->variableDefs = [];
        }, 'leave' => function (OperationDefinitionNode $operation) use($context) {
            $variableNameUsed = [];
            $usages = $context->getRecursiveVariableUsages($operation);
            $opName = $operation->name ? $operation->name->value : null;
            foreach ($usages as $usage) {
                $node = $usage['node'];
                $variableNameUsed[$node->name->value] = true;
            }
            foreach ($this->variableDefs as $variableDef) {
                $variableName = $variableDef->variable->name->value;
                if (empty($variableNameUsed[$variableName])) {
                    $context->reportError(new Error(self::unusedVariableMessage($variableName, $opName), [$variableDef]));
                }
            }
        }], NodeKind::VARIABLE_DEFINITION => function ($def) {
            $this->variableDefs[] = $def;
        }];
    }