datafusion_python/expr/
projection.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use std::fmt::{self, Display, Formatter};
19
20use datafusion::logical_expr::logical_plan::Projection;
21use datafusion::logical_expr::Expr;
22use pyo3::prelude::*;
23use pyo3::IntoPyObjectExt;
24
25use crate::common::df_schema::PyDFSchema;
26use crate::expr::logical_node::LogicalNode;
27use crate::expr::PyExpr;
28use crate::sql::logical::PyLogicalPlan;
29
30#[pyclass(frozen, name = "Projection", module = "datafusion.expr", subclass)]
31#[derive(Clone)]
32pub struct PyProjection {
33    pub projection: Projection,
34}
35
36impl PyProjection {
37    pub fn new(projection: Projection) -> Self {
38        Self { projection }
39    }
40}
41
42impl From<Projection> for PyProjection {
43    fn from(projection: Projection) -> PyProjection {
44        PyProjection { projection }
45    }
46}
47
48impl From<PyProjection> for Projection {
49    fn from(proj: PyProjection) -> Self {
50        proj.projection
51    }
52}
53
54impl Display for PyProjection {
55    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
56        write!(
57            f,
58            "Projection
59            \nExpr(s): {:?}
60            \nInput: {:?}
61            \nProjected Schema: {:?}",
62            &self.projection.expr, &self.projection.input, &self.projection.schema,
63        )
64    }
65}
66
67#[pymethods]
68impl PyProjection {
69    /// Retrieves the expressions for this `Projection`
70    fn projections(&self) -> PyResult<Vec<PyExpr>> {
71        Ok(self
72            .projection
73            .expr
74            .iter()
75            .map(|e| PyExpr::from(e.clone()))
76            .collect())
77    }
78
79    /// Retrieves the input `LogicalPlan` to this `Projection` node
80    fn input(&self) -> PyResult<Vec<PyLogicalPlan>> {
81        Ok(Self::inputs(self))
82    }
83
84    /// Resulting Schema for this `Projection` node instance
85    fn schema(&self) -> PyResult<PyDFSchema> {
86        Ok((*self.projection.schema).clone().into())
87    }
88
89    fn __repr__(&self) -> PyResult<String> {
90        Ok(format!("Projection({self})"))
91    }
92
93    fn __name__(&self) -> PyResult<String> {
94        Ok("Projection".to_string())
95    }
96}
97
98impl PyProjection {
99    /// Projection: Gets the names of the fields that should be projected
100    pub fn projected_expressions(local_expr: &PyExpr) -> Vec<PyExpr> {
101        let mut projs: Vec<PyExpr> = Vec::new();
102        match &local_expr.expr {
103            Expr::Alias(alias) => {
104                let py_expr: PyExpr = PyExpr::from(*alias.expr.clone());
105                projs.extend_from_slice(Self::projected_expressions(&py_expr).as_slice());
106            }
107            _ => projs.push(local_expr.clone()),
108        }
109        projs
110    }
111}
112
113impl LogicalNode for PyProjection {
114    fn inputs(&self) -> Vec<PyLogicalPlan> {
115        vec![PyLogicalPlan::from((*self.projection.input).clone())]
116    }
117
118    fn to_variant<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyAny>> {
119        self.clone().into_bound_py_any(py)
120    }
121}
datafusion_python/expr/projection.rs

datafusion_python/expr/
projection.rs
