Remove unused vector to/from native conversion functions (#70)

Author: robsdedude

changelog.d/70.clean.md

@@ -0,0 +1,2 @@
+Remove now unused helper functions for converting `Vector` values to/from native Python `lists`<ISSUES_LIST>.  
+For more details, see [neo4j-python-driver#1263](https://github.com/neo4j/neo4j-python-driver/pull/1263).

driver

@@ -13,29 +13,65 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-mod native_conversion;
-mod swap_endian;
+use pyo3::exceptions::PyValueError;
+use pyo3::prelude::*;
+use pyo3::types::{PyBytes, PyInt};
+use pyo3::{pyfunction, Bound, PyErr, PyResult};
 
 use crate::register_package;
-use pyo3::prelude::*;
+
+#[pyfunction]
+fn swap_endian<'py>(
+    type_size: Bound<'py, PyInt>,
+    data: Bound<'py, PyBytes>,
+) -> PyResult<Bound<'py, PyBytes>> {
+    let py = type_size.py();
+
+    let type_size: usize = match type_size.extract::<usize>() {
+        Ok(type_size @ 2) | Ok(type_size @ 4) | Ok(type_size @ 8) => type_size,
+        _ => {
+            return Err(PyErr::new::<PyValueError, _>(format!(
+                "Unsupported type size {type_size}",
+            )))
+        }
+    };
+    let bytes = &data.as_bytes();
+    let len = bytes.len();
+    if len % type_size != 0 {
+        return Err(PyErr::new::<PyValueError, _>(
+            "Data length not a multiple of type_size",
+        ));
+    }
+
+    PyBytes::new_with(py, bytes.len(), |out| {
+        match type_size {
+            2 => swap_n::<2>(bytes, out),
+            4 => swap_n::<4>(bytes, out),
+            8 => swap_n::<8>(bytes, out),
+            _ => unreachable!(),
+        }
+        Ok(())
+    })
+}
+
+#[inline(always)]
+fn swap_n<const N: usize>(src: &[u8], dst: &mut [u8]) {
+    // Doesn't technically need to be a function with a const generic, but this
+    // allows the compiler to optimize the code better.
+    assert_eq!(src.len(), dst.len());
+    assert_eq!(src.len() % N, 0);
+    for i in (0..src.len()).step_by(N) {
+        for j in 0..N {
+            dst[i + j] = src[i + N - j - 1];
+        }
+    }
+}
 
 pub(super) fn init_module(m: &Bound<PyModule>, name: &str) -> PyResult<()> {
     m.gil_used(false)?;
     register_package(m, name)?;
 
-    m.add_function(wrap_pyfunction!(swap_endian::swap_endian, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_f64_from_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_f64_to_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_f32_from_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_f32_to_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i64_from_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i64_to_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i32_from_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i32_to_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i16_from_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i16_to_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i8_from_native, m)?)?;
-    m.add_function(wrap_pyfunction!(native_conversion::vec_i8_to_native, m)?)?;
+    m.add_function(wrap_pyfunction!(swap_endian, m)?)?;
 
     Ok(())
 }