CEntityQuery::buildJoinMap

protected function buildJoinMap()
{
	// list of used joins
	$done = array();

	$talias_count = 0;

	foreach ($this->global_chains as $chain)
	{
		if ($chain->getLastElement()->getParameter('talias'))
		{
			// already been here
			continue;
		}

		// in NO_DOUBLING mode skip 1:N relations that presented in filter only
		if (!$this->data_doubling && $chain->hasBackReference())
		{
			$alias = $chain->getAlias();

			if (isset($this->filter_chains[$alias])
				&& !isset($this->select_chains[$alias]) && !isset($this->select_expr_chains[$alias])
				&& !isset($this->group_chains[$alias]) && !isset($this->order_chains[$alias])
			)
			{
				continue;
			}
		}

		$prev_entity = $this->init_entity;
		$prev_alias = CBaseEntity::camel2snake($this->init_entity->getName());

		$map_key = '';

		/**
		 * elemenets after init entity
		 * @var $elements CEntityQueryChainElement[]
		 * */
		$elements = array_slice($chain->getAllElements(), 1);

		foreach ($elements as $element)
		{
			$table_alias = null;

			/**
			 * define main objects
			 * @var $src_entity CBaseEntity
			 * @var $ref_field CReferenceEntityField
			 * @var $dst_entity CBaseEntity
			 */
			if ($element->getValue() instanceof CReferenceEntityField)
			{
				// ref to another entity
				$src_entity = $prev_entity;
				$ref_field = $element->getValue();
				$dst_entity = $ref_field->getRefEntity();
			}
			elseif (is_array($element->getValue())
			)
			{
				// link from another entity to this
				$src_entity = $prev_entity;
				list($dst_entity, $ref_field) = $element->getValue();
			}
			else
			{
				// scalar field
				$element->setParameter('talias', $prev_alias.$this->table_alias_postfix);
				continue;
			}

			// mapping
			if (empty($map_key))
			{
				$map_key = $src_entity->getName();
			}

			$map_key .= '/' . $ref_field->getName() . '/' . $dst_entity->getName();

			if (isset($done[$map_key]))
			{
				// already connected
				$table_alias = $done[$map_key];
			}
			else
			{
				// prepare reference
				$reference = $ref_field->getReference();

				if ($element->getValue() instanceof CReferenceEntityField)
				{
					// ref to another entity
					if (is_null($table_alias))
					{
						$table_alias = $prev_alias.'_'.strtolower($ref_field->getName());

						if (strlen($table_alias.$this->table_alias_postfix) > $this->DB->alias_length)
						{
							$table_alias = 'TALIAS'.$this->table_alias_postfix.'_' . (++$talias_count);
						}
					}

					$alias_this = $prev_alias;
					$alias_ref = $table_alias;
				}
				elseif (is_array($element->getValue()))
				{
					if (is_null($table_alias))
					{
						$table_alias = CBaseEntity::camel2snake($dst_entity->getName()) . '_' . strtolower($ref_field->getName());
						$table_alias = $prev_alias.'_'.$table_alias;

						if (strlen($table_alias.$this->table_alias_postfix) > $this->DB->alias_length)
						{
							$table_alias = 'TALIAS'.$this->table_alias_postfix.'_' . (++$talias_count);
						}
					}

					$alias_this = $table_alias;
					$alias_ref = $prev_alias;

					if ($dst_entity->isUtm())
					{
						// add to $reference
						$reference = array(
							$reference,
							'=this.FIELD_ID' => array('?i', $element->getParameter('ufield')->getFieldId())
						);
					}
				}

				// replace this. and ref. to real definition -- not supported yet
				// instead it we set $alias_this and $alias_ref

				$csw_reference = $this->prepareJoinReference(
					$reference, $alias_this.$this->table_alias_postfix, $alias_ref.$this->table_alias_postfix
				);

				$join = array(
					'type' => $ref_field->getJoinType(),
					'table' => $dst_entity->getDbTableName(),
					'alias' => $table_alias.$this->table_alias_postfix,
					'reference' => $csw_reference
				);

				$this->join_map[] = $join;

				$done[$map_key] = $table_alias;
			}

			// set alias for each element
			$element->setParameter('talias', $table_alias.$this->table_alias_postfix);

			$prev_entity = $dst_entity;
			$prev_alias = $table_alias;
		}
	}
}