Added an as_bytes method for Py<PyBytes>

This allows for obtaining a slice that's not lexically bound to the GIL which can be helpful to avoid copying.
This commit is contained in:
Alex Gaynor 2022-03-19 11:46:40 -04:00
parent 16ad15e04f
commit 69655454c1
3 changed files with 37 additions and 0 deletions

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@ -14,6 +14,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
- Panic during compilation when `PYO3_CROSS_LIB_DIR` is set for some host/target combinations. [#2232](https://github.com/PyO3/pyo3/pull/2232)
### Added
- Added `as_bytes` on `Py<PyBytes>`. [#2235](https://github.com/PyO3/pyo3/pull/2235)
## [0.16.2] - 2022-03-15
### Packaging

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@ -97,6 +97,24 @@ impl PyBytes {
}
}
impl Py<PyBytes> {
/// Gets the Python bytes as a byte slice. Because Python bytes are
/// immutable, the result may be used for as long as the reference to
/// `self` is held, including when the GIL is released.
pub fn as_bytes<'a>(&'a self, _py: Python<'_>) -> &'a [u8] {
// py is required here because `PyBytes_AsString` and `PyBytes_Size`
// can both technically raise exceptions which require the GIL to be
// held. The only circumstance in which they raise is if the value
// isn't really a `PyBytes`, but better safe than sorry.
unsafe {
let buffer = ffi::PyBytes_AsString(self.as_ptr()) as *const u8;
let length = ffi::PyBytes_Size(self.as_ptr()) as usize;
debug_assert!(!buffer.is_null());
std::slice::from_raw_parts(buffer, length)
}
}
}
/// This is the same way [Vec] is indexed.
impl<I: SliceIndex<[u8]>> Index<I> for PyBytes {
type Output = I::Output;

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@ -41,3 +41,18 @@ fn test_bytearray_vec_conversion() {
let f = wrap_pyfunction!(bytes_vec_conversion)(py).unwrap();
py_assert!(py, f, "f(bytearray(b'Hello World')) == b'Hello World'");
}
#[test]
fn test_py_as_bytes() {
let pyobj: pyo3::Py<pyo3::types::PyBytes>;
let data: &[u8];
{
let gil = Python::acquire_gil();
let py = gil.python();
pyobj = pyo3::types::PyBytes::new(py, b"abc").into_py(py);
data = pyobj.as_bytes(py);
}
assert_eq!(data, b"abc");
}