datafusion_python/expr/
empty_relation.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 crate::{common::df_schema::PyDFSchema, sql::logical::PyLogicalPlan};
19use datafusion::logical_expr::EmptyRelation;
20use pyo3::{prelude::*, IntoPyObjectExt};
21use std::fmt::{self, Display, Formatter};
22
23use super::logical_node::LogicalNode;
24
25#[pyclass(name = "EmptyRelation", module = "datafusion.expr", subclass)]
26#[derive(Clone)]
27pub struct PyEmptyRelation {
28    empty: EmptyRelation,
29}
30
31impl From<PyEmptyRelation> for EmptyRelation {
32    fn from(empty_relation: PyEmptyRelation) -> Self {
33        empty_relation.empty
34    }
35}
36
37impl From<EmptyRelation> for PyEmptyRelation {
38    fn from(empty: EmptyRelation) -> PyEmptyRelation {
39        PyEmptyRelation { empty }
40    }
41}
42
43impl Display for PyEmptyRelation {
44    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
45        write!(
46            f,
47            "Empty Relation
48            Produce One Row: {:?}
49            Schema: {:?}",
50            &self.empty.produce_one_row, &self.empty.schema
51        )
52    }
53}
54
55#[pymethods]
56impl PyEmptyRelation {
57    fn produce_one_row(&self) -> PyResult<bool> {
58        Ok(self.empty.produce_one_row)
59    }
60
61    /// Resulting Schema for this `EmptyRelation` node instance
62    fn schema(&self) -> PyResult<PyDFSchema> {
63        Ok((*self.empty.schema).clone().into())
64    }
65
66    /// Get a String representation of this column
67    fn __repr__(&self) -> String {
68        format!("{}", self)
69    }
70
71    fn __name__(&self) -> PyResult<String> {
72        Ok("EmptyRelation".to_string())
73    }
74}
75
76impl LogicalNode for PyEmptyRelation {
77    fn inputs(&self) -> Vec<PyLogicalPlan> {
78        // table scans are leaf nodes and do not have inputs
79        vec![]
80    }
81
82    fn to_variant<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyAny>> {
83        self.clone().into_bound_py_any(py)
84    }
85}
datafusion_python/expr/empty_relation.rs

datafusion_python/expr/
empty_relation.rs
