add PyUnnestExpr wrapper

src/expr.rs

@@ -90,6 +90,7 @@ pub mod subquery_alias;
 pub mod table_scan;
 pub mod union;
 pub mod unnest;
+pub mod unnest_expr;
 pub mod window;
 
 /// A PyExpr that can be used on a DataFrame
@@ -169,7 +170,7 @@ impl PyExpr {
                 Ok(placeholder::PyPlaceholder::from(value.clone()).into_py(py))
             }
             Expr::OuterReferenceColumn(_, _) => todo!(),
-            Expr::Unnest(_) => todo!(),
+            Expr::Unnest(value) => Ok(unnest_expr::PyUnnestExpr::from(value.clone()).into_py(py)),
         })
     }
 
@@ -624,6 +625,7 @@ pub(crate) fn init_module(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<cross_join::PyCrossJoin>()?;
     m.add_class::<union::PyUnion>()?;
     m.add_class::<unnest::PyUnnest>()?;
+    m.add_class::<unnest_expr::PyUnnestExpr>()?;
     m.add_class::<extension::PyExtension>()?;
     m.add_class::<filter::PyFilter>()?;
     m.add_class::<projection::PyProjection>()?;

src/expr/unnest_expr.rs

@@ -0,0 +1,67 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use datafusion_expr::expr::Unnest;
+use pyo3::prelude::*;
+use std::fmt::{self, Display, Formatter};
+
+use super::PyExpr;
+
+#[pyclass(name = "UnnestExpr", module = "datafusion.expr", subclass)]
+#[derive(Clone)]
+pub struct PyUnnestExpr {
+    unnest: Unnest,
+}
+
+impl From<Unnest> for PyUnnestExpr {
+    fn from(unnest: Unnest) -> PyUnnestExpr {
+        PyUnnestExpr { unnest }
+    }
+}
+
+impl From<PyUnnestExpr> for Unnest {
+    fn from(unnest: PyUnnestExpr) -> Self {
+        unnest.unnest
+    }
+}
+
+impl Display for PyUnnestExpr {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(
+            f,
+            "Unnest
+            Expr: {:?}",
+            &self.unnest.expr,
+        )
+    }
+}
+
+#[pymethods]
+impl PyUnnestExpr {
+    /// Retrieves the expression that is being unnested
+    fn expr(&self) -> PyResult<PyExpr> {
+        Ok((*self.unnest.expr).clone().into())
+    }
+
+    fn __repr__(&self) -> PyResult<String> {
+        Ok(format!("UnnestExpr({})", self))
+    }
+
+    fn __name__(&self) -> PyResult<String> {
+        Ok("UnnestExpr".to_string())
+    }
+}