public function __invoke(ValidationContext $context) { $this->operationDefs = []; $this->fragmentDefs = []; return [NodeKind::OPERATION_DEFINITION => function ($node) { $this->operationDefs[] = $node; return Visitor::skipNode(); }, NodeKind::FRAGMENT_DEFINITION => function (FragmentDefinitionNode $def) { $this->fragmentDefs[] = $def; return Visitor::skipNode(); }, NodeKind::DOCUMENT => ['leave' => function () use($context) { $fragmentNameUsed = []; foreach ($this->operationDefs as $operation) { foreach ($context->getRecursivelyReferencedFragments($operation) as $fragment) { $fragmentNameUsed[$fragment->name->value] = true; } } foreach ($this->fragmentDefs as $fragmentDef) { $fragName = $fragmentDef->name->value; if (empty($fragmentNameUsed[$fragName])) { $context->reportError(new Error(self::unusedFragMessage($fragName), [$fragmentDef])); } } }]]; }