risingwave_frontend/optimizer/plan_expr_visitor/
input_ref_counter.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 std::collections::HashMap;
16
17use crate::expr::{ExprVisitor, InputRef};
18
19#[derive(Default)]
20pub struct InputRefCounter {
21    // `input_ref` index -> count
22    pub counter: HashMap<usize, usize>,
23}
24
25impl ExprVisitor for InputRefCounter {
26    fn visit_input_ref(&mut self, input_ref: &InputRef) {
27        self.counter
28            .entry(input_ref.index)
29            .and_modify(|counter| *counter += 1)
30            .or_insert(1);
31    }
32}