returns the first output expression of this `LogicalPlan` node.
(&self)
| 526 | |
| 527 | /// returns the first output expression of this `LogicalPlan` node. |
| 528 | pub fn head_output_expr(&self) -> Result<Option<Expr>> { |
| 529 | match self { |
| 530 | LogicalPlan::Projection(projection) => { |
| 531 | Ok(Some(projection.expr.as_slice()[0].clone())) |
| 532 | } |
| 533 | LogicalPlan::Aggregate(agg) => { |
| 534 | if agg.group_expr.is_empty() { |
| 535 | Ok(Some(agg.aggr_expr.as_slice()[0].clone())) |
| 536 | } else { |
| 537 | Ok(Some(agg.group_expr.as_slice()[0].clone())) |
| 538 | } |
| 539 | } |
| 540 | LogicalPlan::Distinct(Distinct::On(DistinctOn { select_expr, .. })) => { |
| 541 | Ok(Some(select_expr[0].clone())) |
| 542 | } |
| 543 | LogicalPlan::Filter(Filter { input, .. }) |
| 544 | | LogicalPlan::Distinct(Distinct::All(input)) |
| 545 | | LogicalPlan::Sort(Sort { input, .. }) |
| 546 | | LogicalPlan::Limit(Limit { input, .. }) |
| 547 | | LogicalPlan::Repartition(Repartition { input, .. }) |
| 548 | | LogicalPlan::Window(Window { input, .. }) => input.head_output_expr(), |
| 549 | LogicalPlan::Join(Join { |
| 550 | left, |
| 551 | right, |
| 552 | join_type, |
| 553 | .. |
| 554 | }) => match join_type { |
| 555 | JoinType::Inner | JoinType::Left | JoinType::Right | JoinType::Full => { |
| 556 | if left.schema().fields().is_empty() { |
| 557 | right.head_output_expr() |
| 558 | } else { |
| 559 | left.head_output_expr() |
| 560 | } |
| 561 | } |
| 562 | JoinType::LeftSemi | JoinType::LeftAnti | JoinType::LeftMark => { |
| 563 | left.head_output_expr() |
| 564 | } |
| 565 | JoinType::RightSemi | JoinType::RightAnti | JoinType::RightMark => { |
| 566 | right.head_output_expr() |
| 567 | } |
| 568 | }, |
| 569 | LogicalPlan::RecursiveQuery(RecursiveQuery { static_term, .. }) => { |
| 570 | static_term.head_output_expr() |
| 571 | } |
| 572 | LogicalPlan::Union(union) => Ok(Some(Expr::Column(Column::from( |
| 573 | union.schema.qualified_field(0), |
| 574 | )))), |
| 575 | LogicalPlan::TableScan(table) => Ok(Some(Expr::Column(Column::from( |
| 576 | table.projected_schema.qualified_field(0), |
| 577 | )))), |
| 578 | LogicalPlan::SubqueryAlias(subquery_alias) => { |
| 579 | let expr_opt = subquery_alias.input.head_output_expr()?; |
| 580 | expr_opt |
| 581 | .map(|expr| { |
| 582 | Ok(Expr::Column(create_col_from_scalar_expr( |
| 583 | &expr, |
| 584 | subquery_alias.alias.to_string(), |
| 585 | )?)) |