Phalcon\Mvc\Model\EagerLoading\Loader::buildTree PHP Method

    private function buildTree()
    {
        uksort($this->eagerLoads, 'strcmp');
        $di = DI::getDefault();
        $mM = $di['modelsManager'];
        $eagerLoads = $resolvedRelations = [];
        foreach ($this->eagerLoads as $relationAliases => $queryConstraints) {
            $nestingLevel = 0;
            $relationAliases = explode('.', $relationAliases);
            $nestingLevels = count($relationAliases);
            do {
                do {
                    $alias = $relationAliases[$nestingLevel];
                    $name = join('.', array_slice($relationAliases, 0, $nestingLevel + 1));
                } while (isset($eagerLoads[$name]) && ++$nestingLevel);
                if ($nestingLevel === 0) {
                    $parentClassName = $this->subjectClassName;
                } else {
                    $parentName = join('.', array_slice($relationAliases, 0, $nestingLevel));
                    $parentClassName = $resolvedRelations[$parentName]->getReferencedModel();
                    if ($parentClassName[0] === '\\') {
                        ltrim($parentClassName, '\\');
                    }
                }
                if (!isset($resolvedRelations[$name])) {
                    $mM->load($parentClassName);
                    $relation = $mM->getRelationByAlias($parentClassName, $alias);
                    if (!$relation instanceof Relation) {
                        throw new \RuntimeException(sprintf('There is no defined relation for the model `%s` using alias `%s`', $parentClassName, $alias));
                    }
                    $resolvedRelations[$name] = $relation;
                } else {
                    $relation = $resolvedRelations[$name];
                }
                $relType = $relation->getType();
                if ($relType !== Relation::BELONGS_TO && $relType !== Relation::HAS_ONE && $relType !== Relation::HAS_MANY && $relType !== Relation::HAS_MANY_THROUGH) {
                    throw new \RuntimeException(sprintf('Unknown relation type `%s`', $relType));
                }
                if (is_array($relation->getFields()) || is_array($relation->getReferencedFields())) {
                    throw new \RuntimeException('Relations with composite keys are not supported');
                }
                $parent = $nestingLevel > 0 ? $eagerLoads[$parentName] : $this;
                $constraints = $nestingLevel + 1 === $nestingLevels ? $queryConstraints : null;
                $eagerLoads[$name] = new EagerLoad($relation, $constraints, $parent);
            } while (++$nestingLevel < $nestingLevels);
        }
        return $eagerLoads;
    }