GraphQL\Validator\Rules\OverlappingFieldsCanBeMerged::collectFieldNodesAndDefs PHP Method

    private function collectFieldNodesAndDefs(ValidationContext $context, $parentType, SelectionSetNode $selectionSet, \ArrayObject $visitedFragmentNames = null, \ArrayObject $astAndDefs = null)
    {
        $_visitedFragmentNames = $visitedFragmentNames ?: new \ArrayObject();
        $_astAndDefs = $astAndDefs ?: new \ArrayObject();
        for ($i = 0; $i < count($selectionSet->selections); $i++) {
            $selection = $selectionSet->selections[$i];
            switch ($selection->kind) {
                case NodeKind::FIELD:
                    $fieldName = $selection->name->value;
                    $fieldDef = null;
                    if ($parentType && method_exists($parentType, 'getFields')) {
                        $tmp = $parentType->getFields();
                        if (isset($tmp[$fieldName])) {
                            $fieldDef = $tmp[$fieldName];
                        }
                    }
                    $responseName = $selection->alias ? $selection->alias->value : $fieldName;
                    if (!isset($_astAndDefs[$responseName])) {
                        $_astAndDefs[$responseName] = new \ArrayObject();
                    }
                    $_astAndDefs[$responseName][] = [$parentType, $selection, $fieldDef];
                    break;
                case NodeKind::INLINE_FRAGMENT:
                    $typeCondition = $selection->typeCondition;
                    $inlineFragmentType = $typeCondition ? TypeInfo::typeFromAST($context->getSchema(), $typeCondition) : $parentType;
                    $_astAndDefs = $this->collectFieldNodesAndDefs($context, $inlineFragmentType, $selection->selectionSet, $_visitedFragmentNames, $_astAndDefs);
                    break;
                case NodeKind::FRAGMENT_SPREAD:
                    /** @var FragmentSpreadNode $selection */
                    $fragName = $selection->name->value;
                    if (!empty($_visitedFragmentNames[$fragName])) {
                        continue;
                    }
                    $_visitedFragmentNames[$fragName] = true;
                    $fragment = $context->getFragment($fragName);
                    if (!$fragment) {
                        continue;
                    }
                    $fragmentType = TypeInfo::typeFromAST($context->getSchema(), $fragment->typeCondition);
                    $_astAndDefs = $this->collectFieldNodesAndDefs($context, $fragmentType, $fragment->selectionSet, $_visitedFragmentNames, $_astAndDefs);
                    break;
            }
        }
        return $_astAndDefs;
    }