Expose Transforms to Python Binding

.github/workflows/bindings_python_ci.yml

@@ -78,6 +78,6 @@ jobs:
         shell: bash
         run: |
           set -e
-          pip install dist/pyiceberg_core-*.whl --force-reinstall
-          pip install pytest
-          pytest -v
+          pip install hatch==1.12.0
+          hatch run dev:pip install dist/pyiceberg_core-*.whl --force-reinstall
+          hatch run dev:test

.gitignore

@@ -24,3 +24,5 @@ dist/*
 **/venv
 *.so
 *.pyc
+*.whl
+*.tar.gz

.licenserc.yaml

@@ -31,4 +31,6 @@ header:
     - '**/DEPENDENCIES.*.tsv'
     # Release distributions
     - 'dist/*'
+    # Generated content by poetry
+    - poetry.lock
   comment: on-failure

bindings/python/Cargo.toml

@@ -33,3 +33,5 @@ crate-type = ["cdylib"]
 [dependencies]
 iceberg = { path = "../../crates/iceberg" }
 pyo3 = { version = "0.22", features = ["extension-module"] }
+arrow = { version = "52.2.0", features = ["ffi"] }
+libc = "0.2"

bindings/python/README.md

@@ -24,21 +24,17 @@ This project is used to build an iceberg-rust powered core for pyiceberg.
 ## Setup
 
 ```shell
-python -m venv venv
-source ./venv/bin/activate
-
-pip install maturin
+pip install hatch==1.12.0
 ```
 
 ## Build
 
 ```shell
-maturin develop
+hatch run dev:develop
 ```
 
 ## Test
 
 ```shell
-maturin develop -E test
-pytest -v
+hatch run dev:test
 ```

bindings/python/pyproject.toml

@@ -31,13 +31,22 @@ classifiers = [
   "Programming Language :: Python :: 3.12",
 ]
 
-[project.optional-dependencies]
-test = ["pytest"]
-
 [tool.maturin]
 features = ["pyo3/extension-module"]
 python-source = "python"
 module-name = "pyiceberg_core.pyiceberg_core_rust"
 
 [tool.ruff.lint]
 ignore = ["F403", "F405"]
+
+[tool.hatch.envs.dev]
+dependencies = [
+    "maturin>=1.0,<2.0",
+    "pytest>=8.3.2",
+    "pyarrow>=17.0.0",
+]
+
+[tool.hatch.envs.dev.scripts]
+develop = "maturin develop"
+build = "maturin build --out dist --sdist"
+test = "pytest"

bindings/python/src/lib.rs

@@ -17,6 +17,9 @@
 
 use iceberg::io::FileIOBuilder;
 use pyo3::prelude::*;
+use pyo3::wrap_pyfunction;
+
+mod transform;
 
 #[pyfunction]
 fn hello_world() -> PyResult<String> {
@@ -26,6 +29,8 @@ fn hello_world() -> PyResult<String> {
 
 #[pymodule]
 fn pyiceberg_core_rust(m: &Bound<'_, PyModule>) -> PyResult<()> {
+    use transform::bucket_transform;
     m.add_function(wrap_pyfunction!(hello_world, m)?)?;
+    m.add_function(wrap_pyfunction!(bucket_transform, m)?)?;
     Ok(())
 }

bindings/python/src/transform.rs

@@ -0,0 +1,142 @@
+// 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 std::{error, fmt, sync::Arc};
+use iceberg::spec::Transform;
+use iceberg::transform::create_transform_function;
+use iceberg::Error;
+
+use arrow::{
+    array::{make_array, Array, ArrayData, ArrayRef},
+    error::ArrowError,
+    ffi::{from_ffi, to_ffi},
+};
+use libc::uintptr_t;
+use pyo3::{exceptions::PyOSError, exceptions::PyValueError, prelude::*};
+
+#[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())
+    }
+}
+
+#[derive(Debug)]
+enum PyO3IcebergError {
+    Error(Error),
+}
+
+impl fmt::Display for PyO3IcebergError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            PyO3IcebergError::Error(ref e) => e.fmt(f),
+        }
+    }
+}
+
+impl error::Error for PyO3IcebergError {
+    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.
+            PyO3IcebergError::Error(ref e) => Some(e),
+        }
+    }
+}
+
+impl From<Error> for PyO3IcebergError {
+    fn from(err: Error) -> PyO3IcebergError {
+        PyO3IcebergError::Error(err)
+    }
+}
+
+impl From<PyO3IcebergError> for PyErr {
+    fn from(err: PyO3IcebergError) -> PyErr {
+        PyValueError::new_err(err.to_string())
+    }
+}
+
+fn to_rust_arrow_array(ob: PyObject, py: Python) -> PyResult<ArrayRef> {
+    // prepare a pointer to receive the Array struct
+    let (array, schema) = to_ffi(&ArrayData::new_empty(&arrow::datatypes::DataType::Null))
+        .map_err(PyO3ArrowError::from)?;
+    let array_pointer = &array as *const _ as uintptr_t;
+    let schema_pointer = &schema as *const _ as uintptr_t;
+
+    // make the conversion through PyArrow's private API
+    // this changes the pointer's memory and is thus unsafe. In particular, `_export_to_c` can go out of bounds
+    ob.call_method1(py, "_export_to_c", (array_pointer, schema_pointer))?;
+
+    let array = unsafe { from_ffi(array, &schema) }.map_err(PyO3ArrowError::from)?;
+    let array = make_array(array);
+    Ok(array)
+}
+
+fn to_pyarrow_array(array: ArrayRef, py: Python) -> PyResult<PyObject> {
+    let (array, schema) = to_ffi(&array.to_data()).map_err(PyO3ArrowError::from)?;
+    let array_pointer = &array as *const _ as uintptr_t;
+    let schema_pointer = &schema as *const _ as uintptr_t;
+
+    let pa = py.import_bound("pyarrow")?;
+
+    let array = pa.getattr("Array")?.call_method1(
+        "_import_from_c",
+        (array_pointer as uintptr_t, schema_pointer as uintptr_t),
+    )?;
+    Ok(array.to_object(py))
+}
+
+#[pyfunction]
+pub fn bucket_transform(array: PyObject, num_buckets: u32, py: Python) -> PyResult<PyObject> {
+    // import
+    let array = to_rust_arrow_array(array, py)?;
+    let bucket = create_transform_function(&Transform::Bucket(num_buckets)).map_err(PyO3IcebergError::from)?;
+    let array = bucket.transform(array).map_err(PyO3IcebergError::from)?;
+    let array = Arc::new(array);
+    // export
+    to_pyarrow_array(array, py)
+}

bindings/python/tests/test_transform.py

@@ -0,0 +1,49 @@
+# 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.
+
+from pyiceberg_core import bucket_transform
+
+import pytest
+import pyarrow as pa
+
+
+def test_bucket_pyarrow_array():
+    arr = pa.array([1, 2])
+    result = bucket_transform(arr, 10)
+    expected = pa.array([6, 2], type=pa.int32())
+    assert result == expected
+
+
+def test_bucket_pyarrow_array_list_type_fails():
+    arr = pa.array([[1, 2], [3, 4]])
+    with pytest.raises(
+        ValueError,
+        match=r"FeatureUnsupported => Unsupported data type for bucket transform",
+    ):
+        bucket_transform(arr, 10)
+
+
+def test_bucket_chunked_array():
+    chunked = pa.chunked_array([pa.array([1, 2]), pa.array([3, 4])])
+    result_chunks = []
+    for arr in chunked.iterchunks():
+        result_chunks.append(bucket_transform(arr, 10))
+
+    expected = pa.chunked_array(
+        [pa.array([6, 2], type=pa.int32()), pa.array([5, 0], type=pa.int32())]
+    )
+    assert pa.chunked_array(result_chunks).equals(expected)