🚚 Move pyo3 functions under src/python/adapters.rs (#9)

Removing all pyo3 wrapper code from src/lib.rs, and putting them in src/python/adapters.rs instead to more clearly separate Rust and Python bindings. Also created a path_to_stream function to isolate the object_store code from the ndarray conversion code.

python/tests/test_io_geotiff.py

@@ -1,13 +1,15 @@
 """
 Test I/O on GeoTIFF files.
 """
+import os
 import tempfile
 import urllib.request
-import os
+
 import pytest
 
 from cog3pio import read_geotiff
 
+
 # %%
 @pytest.fixture(scope="module", name="geotiff_path")
 def fixture_geotiff_path():

src/lib.rs

@@ -46,84 +46,5 @@
 
 /// Modules for handling Input/Output of GeoTIFF data
 pub mod io;
-
-use std::io::Cursor;
-
-use bytes::Bytes;
-use ndarray::Dim;
-use numpy::{PyArray, ToPyArray};
-use object_store::{parse_url, ObjectStore};
-use pyo3::exceptions::{PyBufferError, PyFileNotFoundError, PyValueError};
-use pyo3::prelude::{pyfunction, pymodule, PyModule, PyResult, Python};
-use pyo3::{wrap_pyfunction, PyErr};
-use url::Url;
-
-/// Read a GeoTIFF file from a path on disk into an ndarray
-///
-/// Parameters
-/// ----------
-/// path : str
-///     The path to the file, or a url to a remote file.
-///
-/// Returns
-/// -------
-/// array : np.ndarray
-///     2D array containing the GeoTIFF pixel data.
-///
-/// Examples
-/// --------
-/// from cog3pio import read_geotiff
-///
-/// array = read_geotiff("https://github.com/pka/georaster/raw/v0.1.0/data/tiff/float32.tif")
-/// assert array.shape == (20, 20)
-#[pyfunction]
-#[pyo3(name = "read_geotiff")]
-fn read_geotiff_py<'py>(
-    path: &str,
-    py: Python<'py>,
-) -> PyResult<&'py PyArray<f32, Dim<[usize; 2]>>> {
-    // Parse URL into ObjectStore and path
-    let file_or_url = match Url::from_file_path(path) {
-        // Parse local filepath
-        Ok(filepath) => filepath,
-        // Parse remote URL
-        Err(_) => Url::parse(path)
-            .map_err(|_| PyValueError::new_err(format!("Cannot parse path: {path}")))?,
-    };
-    let (store, location) = parse_url(&file_or_url)
-        .map_err(|_| PyValueError::new_err(format!("Cannot parse url: {file_or_url}")))?;
-
-    // Initialize async runtime
-    let runtime = tokio::runtime::Builder::new_current_thread()
-        .enable_all()
-        .build()?;
-
-    // Get TIFF file stream asynchronously
-    let stream = runtime.block_on(async {
-        let result = store
-            .get(&location)
-            .await
-            .map_err(|_| PyFileNotFoundError::new_err(format!("Cannot find file: {path}")))?;
-        let bytes = result.bytes().await.map_err(|_| {
-            PyBufferError::new_err(format!("Failed to stream data from {path} into bytes."))
-        })?;
-        // Return cursor to in-memory buffer
-        Ok::<Cursor<Bytes>, PyErr>(Cursor::new(bytes))
-    })?;
-
-    // Get image pixel data as an ndarray
-    let vec_data = io::geotiff::read_geotiff(stream)
-        .map_err(|err| PyValueError::new_err(format!("Cannot read GeoTIFF because: {err}")))?;
-
-    // Convert from ndarray (Rust) to numpy ndarray (Python)
-    Ok(vec_data.to_pyarray(py))
-}
-
-/// A Python module implemented in Rust. The name of this function must match
-/// the `lib.name` setting in the `Cargo.toml`, else Python will not be able to
-/// import the module.
-#[pymodule]
-fn cog3pio(_py: Python, m: &PyModule) -> PyResult<()> {
-    m.add_function(wrap_pyfunction!(read_geotiff_py, m)?)?;
-    Ok(())
-}
+/// Modules for Python to interface with Rust code
+pub mod python;

src/python/adapters.rs

@@ -0,0 +1,87 @@
+use std::io::Cursor;
+
+use bytes::Bytes;
+use numpy::{PyArray2, ToPyArray};
+use object_store::{parse_url, ObjectStore};
+use pyo3::exceptions::{PyBufferError, PyFileNotFoundError, PyValueError};
+use pyo3::prelude::{pyfunction, pymodule, PyModule, PyResult, Python};
+use pyo3::wrap_pyfunction;
+use pyo3::PyErr;
+use url::Url;
+
+use crate::io::geotiff::read_geotiff;
+
+/// Read from a filepath or url into a byte stream
+fn path_to_stream(path: &str) -> PyResult<Cursor<Bytes>> {
+    // Parse URL into ObjectStore and path
+    let file_or_url = match Url::from_file_path(path) {
+        // Parse local filepath
+        Ok(filepath) => filepath,
+        // Parse remote URL
+        Err(_) => Url::parse(path)
+            .map_err(|_| PyValueError::new_err(format!("Cannot parse path: {path}")))?,
+    };
+    let (store, location) = parse_url(&file_or_url)
+        .map_err(|_| PyValueError::new_err(format!("Cannot parse url: {file_or_url}")))?;
+
+    // Initialize async runtime
+    let runtime = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()?;
+
+    // Get TIFF file stream asynchronously
+    let stream = runtime.block_on(async {
+        let result = store
+            .get(&location)
+            .await
+            .map_err(|_| PyFileNotFoundError::new_err(format!("Cannot find file: {path}")))?;
+        let bytes = result.bytes().await.map_err(|_| {
+            PyBufferError::new_err(format!("Failed to stream data from {path} into bytes."))
+        })?;
+        // Return cursor to in-memory buffer
+        Ok::<Cursor<Bytes>, PyErr>(Cursor::new(bytes))
+    })?;
+    Ok(stream)
+}
+
+/// Read a GeoTIFF file from a path on disk into an ndarray
+///
+/// Parameters
+/// ----------
+/// path : str
+///     The path to the file, or a url to a remote file.
+///
+/// Returns
+/// -------
+/// array : np.ndarray
+///     2D array containing the GeoTIFF pixel data.
+///
+/// Examples
+/// --------
+/// from cog3pio import read_geotiff
+///
+/// array = read_geotiff("https://github.com/pka/georaster/raw/v0.1.0/data/tiff/float32.tif")
+/// assert array.shape == (20, 20)
+#[pyfunction]
+#[pyo3(name = "read_geotiff")]
+fn read_geotiff_py<'py>(path: &str, py: Python<'py>) -> PyResult<&'py PyArray2<f32>> {
+    // Parse URL into byte stream
+    let stream = path_to_stream(path)?;
+
+    // Get image pixel data as an ndarray
+    let vec_data = read_geotiff(stream)
+        .map_err(|err| PyValueError::new_err(format!("Cannot read GeoTIFF because: {err}")))?;
+
+    // Convert from ndarray (Rust) to numpy ndarray (Python)
+    Ok(vec_data.to_pyarray(py))
+}
+
+/// A Python module implemented in Rust. The name of this function must match
+/// the `lib.name` setting in the `Cargo.toml`, else Python will not be able to
+/// import the module.
+#[pymodule]
+fn cog3pio(_py: Python, m: &PyModule) -> PyResult<()> {
+    // Register Python functions
+    m.add_function(wrap_pyfunction!(read_geotiff_py, m)?)?;
+    Ok(())
+}

src/python/mod.rs

@@ -0,0 +1,2 @@
+/// Adapter interface from Rust to Python
+pub mod adapters;