[GitHub] [arrow] nevi-me commented on a change in pull request #8401: ARROW-10109: [Rust] Add support to the C data interface for primitive types and utf8

[GitBox <gi...@apache.org>]

nevi-me commented on a change in pull request #8401:
URL: https://github.com/apache/arrow/pull/8401#discussion_r506980094



##########
File path: rust/arrow-c-integration/src/lib.rs
##########
@@ -0,0 +1,162 @@
+// 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.
+
+//! This library demonstrates a minimal usage of Rust's C data interface to pass
+//! arrays from and to Python.
+
+use std::error;
+use std::fmt;
+use std::sync::Arc;
+
+use pyo3::exceptions::PyOSError;
+use pyo3::wrap_pyfunction;
+use pyo3::{libc::uintptr_t, prelude::*};
+
+use arrow::array::{make_array_from_raw, ArrayRef, Int64Array};
+use arrow::compute::kernels;
+use arrow::error::ArrowError;
+use arrow::ffi;
+
+/// an error that bridges ArrowError with a Python error
+#[derive(Debug)]
+enum PyO3ArrowError {
+    ArrowError(ArrowError),
+}
+
+impl fmt::Display for PyO3ArrowError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            PyO3ArrowError::ArrowError(ref e) => e.fmt(f),
+        }
+    }
+}
+
+impl error::Error for PyO3ArrowError {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        match *self {
+            // The cause is the underlying implementation error type. Is implicitly
+            // cast to the trait object `&error::Error`. This works because the
+            // underlying type already implements the `Error` trait.
+            PyO3ArrowError::ArrowError(ref e) => Some(e),
+        }
+    }
+}
+
+impl From<ArrowError> for PyO3ArrowError {
+    fn from(err: ArrowError) -> PyO3ArrowError {
+        PyO3ArrowError::ArrowError(err)
+    }
+}
+
+impl From<PyO3ArrowError> for PyErr {
+    fn from(err: PyO3ArrowError) -> PyErr {
+        PyOSError::new_err(err.to_string())
+    }
+}
+
+fn to_rust(ob: PyObject, py: Python) -> PyResult<ArrayRef> {
+    // prepare a pointer to receive the Array struct
+    let (array_pointer, schema_pointer) =
+        ffi::ArrowArray::into_raw(unsafe { ffi::ArrowArray::empty() });
+
+    // make the conversion through PyArrow's private API

Review comment:
       Do we run the risk of a private API being changed breaking this?




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