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 std::fmt::{self, Display, Formatter};
19
20use datafusion::logical_expr::EmptyRelation;
21use pyo3::IntoPyObjectExt;
22use pyo3::prelude::*;
23
24use super::logical_node::LogicalNode;
25use crate::common::df_schema::PyDFSchema;
26use crate::sql::logical::PyLogicalPlan;
27
28#[pyclass(
29    from_py_object,
30    frozen,
31    name = "EmptyRelation",
32    module = "datafusion.expr",
33    subclass
34)]
35#[derive(Clone)]
36pub struct PyEmptyRelation {
37    empty: EmptyRelation,
38}
39
40impl From<PyEmptyRelation> for EmptyRelation {
41    fn from(empty_relation: PyEmptyRelation) -> Self {
42        empty_relation.empty
43    }
44}
45
46impl From<EmptyRelation> for PyEmptyRelation {
47    fn from(empty: EmptyRelation) -> PyEmptyRelation {
48        PyEmptyRelation { empty }
49    }
50}
51
52impl Display for PyEmptyRelation {
53    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
54        write!(
55            f,
56            "Empty Relation
57            Produce One Row: {:?}
58            Schema: {:?}",
59            &self.empty.produce_one_row, &self.empty.schema
60        )
61    }
62}
63
64#[pymethods]
65impl PyEmptyRelation {
66    fn produce_one_row(&self) -> PyResult<bool> {
67        Ok(self.empty.produce_one_row)
68    }
69
70    /// Resulting Schema for this `EmptyRelation` node instance
71    fn schema(&self) -> PyResult<PyDFSchema> {
72        Ok((*self.empty.schema).clone().into())
73    }
74
75    /// Get a String representation of this column
76    fn __repr__(&self) -> String {
77        format!("{self}")
78    }
79
80    fn __name__(&self) -> PyResult<String> {
81        Ok("EmptyRelation".to_string())
82    }
83}
84
85impl LogicalNode for PyEmptyRelation {
86    fn inputs(&self) -> Vec<PyLogicalPlan> {
87        // table scans are leaf nodes and do not have inputs
88        vec![]
89    }
90
91    fn to_variant<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyAny>> {
92        self.clone().into_bound_py_any(py)
93    }
94}
datafusion_python/expr/empty_relation.rs

datafusion_python/expr/
empty_relation.rs
