risingwave_frontend/expr/
correlated_input_ref.rs

1// Copyright 2025 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use core::fmt;
16
17use risingwave_common::types::DataType;
18
19use super::Expr;
20
21pub type Depth = usize;
22pub type CorrelatedId = u32;
23
24/// Relative `Depth` is the number of of nesting levels of the subquery relative to the referred
25/// relation, and should be non-zero.
26/// Absolute `CorrelatedId` is the id of the related Apply operator, and should be non-zero.
27#[derive(Clone, Eq, PartialEq, Hash)]
28pub enum Position {
29    Relative(Depth),
30    Absolute(CorrelatedId),
31}
32
33/// A reference to a column outside the subquery.
34///
35/// `index` is the index in the referred relation.
36/// `position` has two mode Relative and Absolute.
37/// For binding we use relative position, for optimization we use absolute position.
38#[derive(Clone, Eq, PartialEq, Hash)]
39pub struct CorrelatedInputRef {
40    index: usize,
41    data_type: DataType,
42    position: Position,
43}
44
45impl CorrelatedInputRef {
46    pub fn new(index: usize, data_type: DataType, depth: usize) -> Self {
47        CorrelatedInputRef {
48            index,
49            data_type,
50            position: Position::Relative(depth),
51        }
52    }
53
54    /// Get a reference to the input ref's index.
55    pub fn index(&self) -> usize {
56        self.index
57    }
58
59    pub fn depth(&self) -> usize {
60        match self.position {
61            Position::Relative(depth) => depth,
62            Position::Absolute(_) => 0,
63        }
64    }
65
66    pub fn set_correlated_id(&mut self, correlated_id: CorrelatedId) {
67        self.position = Position::Absolute(correlated_id);
68    }
69
70    pub fn correlated_id(&self) -> CorrelatedId {
71        match self.position {
72            Position::Relative(_) => 0,
73            Position::Absolute(correlated_id) => correlated_id,
74        }
75    }
76}
77
78impl Expr for CorrelatedInputRef {
79    fn return_type(&self) -> DataType {
80        self.data_type.clone()
81    }
82
83    fn to_expr_proto(&self) -> risingwave_pb::expr::ExprNode {
84        unreachable!("CorrelatedInputRef {:?} has not been decorrelated", self)
85    }
86}
87
88impl fmt::Debug for CorrelatedInputRef {
89    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
90        f.debug_struct("CorrelatedInputRef")
91            .field("index", &self.index)
92            .field("correlated_id", &self.correlated_id())
93            .finish()
94    }
95}
risingwave_frontend/expr/correlated_input_ref.rs

risingwave_frontend/expr/
correlated_input_ref.rs
