use crate::{exceptions, PyErr};
#[cfg(min_const_generics)]
mod min_const_generics {
use super::invalid_sequence_length;
use crate::{FromPyObject, IntoPy, PyAny, PyObject, PyResult, PyTryFrom, Python, ToPyObject};
impl<T, const N: usize> IntoPy<PyObject> for [T; N]
where
T: ToPyObject,
{
fn into_py(self, py: Python) -> PyObject {
self.as_ref().to_object(py)
}
}
impl<'a, T, const N: usize> FromPyObject<'a> for [T; N]
where
T: FromPyObject<'a>,
{
#[cfg(not(feature = "nightly"))]
fn extract(obj: &'a PyAny) -> PyResult<Self> {
create_array_from_obj(obj)
}
#[cfg(feature = "nightly")]
default fn extract(obj: &'a PyAny) -> PyResult<Self> {
create_array_from_obj(obj)
}
}
#[cfg(all(feature = "nightly", not(Py_LIMITED_API)))]
impl<'source, T, const N: usize> FromPyObject<'source> for [T; N]
where
for<'a> T: Default + FromPyObject<'a> + crate::buffer::Element,
{
fn extract(obj: &'source PyAny) -> PyResult<Self> {
use crate::AsPyPointer;
if unsafe { crate::ffi::PyObject_CheckBuffer(obj.as_ptr()) } == 1 {
if let Ok(buf) = crate::buffer::PyBuffer::get(obj) {
let mut array = [T::default(); N];
if buf.dimensions() == 1 && buf.copy_to_slice(obj.py(), &mut array).is_ok() {
buf.release(obj.py());
return Ok(array);
}
buf.release(obj.py());
}
}
create_array_from_obj(obj)
}
}
fn create_array_from_obj<'s, T, const N: usize>(obj: &'s PyAny) -> PyResult<[T; N]>
where
T: FromPyObject<'s>,
{
let seq = <crate::types::PySequence as PyTryFrom>::try_from(obj)?;
let seq_len = seq.len()? as usize;
if seq_len != N {
return Err(invalid_sequence_length(N, seq_len));
}
array_try_from_fn(|idx| seq.get_item(idx).and_then(PyAny::extract))
}
fn array_try_from_fn<E, F, T, const N: usize>(mut cb: F) -> Result<[T; N], E>
where
F: FnMut(usize) -> Result<T, E>,
{
struct ArrayGuard<T, const N: usize> {
dst: *mut T,
initialized: usize,
}
impl<T, const N: usize> Drop for ArrayGuard<T, N> {
fn drop(&mut self) {
debug_assert!(self.initialized <= N);
let initialized_part =
core::ptr::slice_from_raw_parts_mut(self.dst, self.initialized);
unsafe {
core::ptr::drop_in_place(initialized_part);
}
}
}
let mut array: core::mem::MaybeUninit<[T; N]> = core::mem::MaybeUninit::uninit();
let mut guard: ArrayGuard<T, N> = ArrayGuard {
dst: array.as_mut_ptr() as _,
initialized: 0,
};
unsafe {
let mut value_ptr = array.as_mut_ptr() as *mut T;
for i in 0..N {
core::ptr::write(value_ptr, cb(i)?);
value_ptr = value_ptr.offset(1);
guard.initialized += 1;
}
core::mem::forget(guard);
Ok(array.assume_init())
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::{
panic,
sync::atomic::{AtomicUsize, Ordering},
};
#[test]
fn array_try_from_fn() {
static DROP_COUNTER: AtomicUsize = AtomicUsize::new(0);
struct CountDrop;
impl Drop for CountDrop {
fn drop(&mut self) {
DROP_COUNTER.fetch_add(1, Ordering::SeqCst);
}
}
let _ = catch_unwind_silent(move || {
let _: Result<[CountDrop; 4], ()> = super::array_try_from_fn(|idx| {
if idx == 2 {
panic!("peek a boo");
}
Ok(CountDrop)
});
});
assert_eq!(DROP_COUNTER.load(Ordering::SeqCst), 2);
}
#[test]
fn test_extract_bytearray_to_array() {
Python::with_gil(|py| {
let v: [u8; 33] = py
.eval(
"bytearray(b'abcabcabcabcabcabcabcabcabcabcabc')",
None,
None,
)
.unwrap()
.extract()
.unwrap();
assert!(&v == b"abcabcabcabcabcabcabcabcabcabcabc");
})
}
fn catch_unwind_silent<F, R>(f: F) -> std::thread::Result<R>
where
F: FnOnce() -> R + panic::UnwindSafe,
{
let prev_hook = panic::take_hook();
panic::set_hook(Box::new(|_| {}));
let result = panic::catch_unwind(f);
panic::set_hook(prev_hook);
result
}
}
}
#[cfg(not(min_const_generics))]
mod array_impls {
use super::invalid_sequence_length;
use crate::{FromPyObject, IntoPy, PyAny, PyObject, PyResult, PyTryFrom, Python, ToPyObject};
macro_rules! array_impls {
($($N:expr),+) => {
$(
impl<T> IntoPy<PyObject> for [T; $N]
where
T: ToPyObject
{
fn into_py(self, py: Python) -> PyObject {
self.as_ref().to_object(py)
}
}
impl<'a, T> FromPyObject<'a> for [T; $N]
where
T: Copy + Default + FromPyObject<'a>,
{
#[cfg(not(feature = "nightly"))]
fn extract(obj: &'a PyAny) -> PyResult<Self> {
let mut array = [T::default(); $N];
extract_sequence_into_slice(obj, &mut array)?;
Ok(array)
}
#[cfg(feature = "nightly")]
default fn extract(obj: &'a PyAny) -> PyResult<Self> {
let mut array = [T::default(); $N];
extract_sequence_into_slice(obj, &mut array)?;
Ok(array)
}
}
#[cfg(feature = "nightly")]
impl<'source, T> FromPyObject<'source> for [T; $N]
where
for<'a> T: Default + FromPyObject<'a> + crate::buffer::Element,
{
fn extract(obj: &'source PyAny) -> PyResult<Self> {
let mut array = [T::default(); $N];
if unsafe { crate::ffi::PyObject_CheckBuffer(obj.as_ptr()) } == 1 {
if let Ok(buf) = crate::buffer::PyBuffer::get(obj) {
if buf.dimensions() == 1 && buf.copy_to_slice(obj.py(), &mut array).is_ok() {
buf.release(obj.py());
return Ok(array);
}
buf.release(obj.py());
}
}
extract_sequence_into_slice(obj, &mut array)?;
Ok(array)
}
}
)+
}
}
#[cfg(not(min_const_generics))]
array_impls!(
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
25, 26, 27, 28, 29, 30, 31, 32
);
#[cfg(not(min_const_generics))]
fn extract_sequence_into_slice<'s, T>(obj: &'s PyAny, slice: &mut [T]) -> PyResult<()>
where
T: FromPyObject<'s>,
{
let seq = <crate::types::PySequence as PyTryFrom>::try_from(obj)?;
let seq_len = seq.len()? as usize;
if seq_len != slice.len() {
return Err(invalid_sequence_length(slice.len(), seq_len));
}
for (value, item) in slice.iter_mut().zip(seq.iter()?) {
*value = item?.extract::<T>()?;
}
Ok(())
}
}
fn invalid_sequence_length(expected: usize, actual: usize) -> PyErr {
exceptions::PyValueError::new_err(format!(
"expected a sequence of length {} (got {})",
expected, actual
))
}
#[cfg(test)]
mod tests {
use crate::{PyResult, Python};
#[test]
fn test_extract_small_bytearray_to_array() {
Python::with_gil(|py| {
let v: [u8; 3] = py
.eval("bytearray(b'abc')", None, None)
.unwrap()
.extract()
.unwrap();
assert!(&v == b"abc");
});
}
#[test]
fn test_extract_invalid_sequence_length() {
Python::with_gil(|py| {
let v: PyResult<[u8; 3]> = py
.eval("bytearray(b'abcdefg')", None, None)
.unwrap()
.extract();
assert_eq!(
v.unwrap_err().to_string(),
"ValueError: expected a sequence of length 3 (got 7)"
);
})
}
}