examples/datafusion-ffi-example/src/table_function.rs

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// distributed with this work for additional information
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// 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
//
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use crate::table_provider::MyTableProvider;
use datafusion::catalog::{TableFunctionImpl, TableProvider};
use datafusion::error::Result as DataFusionResult;
use datafusion::prelude::Expr;
use datafusion_ffi::udtf::FFI_TableFunction;
use pyo3::types::PyCapsule;
use pyo3::{pyclass, pymethods, Bound, PyResult, Python};
use std::sync::Arc;

#[pyclass(name = "MyTableFunction", module = "datafusion_ffi_example", subclass)]
#[derive(Debug, Clone)]
pub(crate) struct MyTableFunction {}

#[pymethods]
impl MyTableFunction {
    #[new]
    fn new() -> Self {
        Self {}
    }

    fn __datafusion_table_function__<'py>(
        &self,
        py: Python<'py>,
    ) -> PyResult<Bound<'py, PyCapsule>> {
        let name = cr"datafusion_table_function".into();

        let func = self.clone();
        let provider = FFI_TableFunction::new(Arc::new(func), None);

        PyCapsule::new(py, provider, Some(name))
    }
}

impl TableFunctionImpl for MyTableFunction {
    fn call(&self, _args: &[Expr]) -> DataFusionResult<Arc<dyn TableProvider>> {
        let provider = MyTableProvider::new(4, 3, 2).create_table()?;
        Ok(Arc::new(provider))
    }
}