Function extractLeftTableExpression

src/Analyzer/Utils.cpp:685–743

}

QueryTreeNodePtr extractLeftTableExpression(const QueryTreeNodePtr & join_tree_node)
{
    QueryTreeNodePtr result;

    std::deque<QueryTreeNodePtr> nodes_to_process;
    nodes_to_process.push_back(join_tree_node);

    while (!result)
    {
        auto node_to_process = std::move(nodes_to_process.front());
        nodes_to_process.pop_front();

        auto node_type = node_to_process->getNodeType();

        switch (node_type)
        {
            case QueryTreeNodeType::IDENTIFIER:
                [[fallthrough]];
            case QueryTreeNodeType::TABLE:
                [[fallthrough]];
            case QueryTreeNodeType::QUERY:
                [[fallthrough]];
            case QueryTreeNodeType::UNION:
                [[fallthrough]];
            case QueryTreeNodeType::TABLE_FUNCTION:
            {
                result = std::move(node_to_process);
                break;
            }
            case QueryTreeNodeType::ARRAY_JOIN:
            {
                auto & array_join_node = node_to_process->as<ArrayJoinNode &>();
                nodes_to_process.push_front(array_join_node.getTableExpression());
                break;
            }
            case QueryTreeNodeType::CROSS_JOIN:
            {
                auto & cross_join_node = node_to_process->as<CrossJoinNode &>();
                nodes_to_process.push_front(cross_join_node.getTableExpressions().front());
                break;
            }
            case QueryTreeNodeType::JOIN:
            {
                auto & join_node = node_to_process->as<JoinNode &>();
                nodes_to_process.push_front(join_node.getLeftTableExpression());
                break;
            }
            default:
            {
                throw Exception(ErrorCodes::LOGICAL_ERROR,
                                "Unexpected node type for table expression. "
                                "Expected table, table function, query, union, join or array join. Actual {}",
                                node_to_process->getNodeTypeName());
            }
        }
    }

    return result;