Merge pull request #3680 from davidhewitt/list2

implement `PyListMethods`

Author: davidhewitt

src/instance.rs

@@ -221,13 +221,26 @@ unsafe impl<T> AsPyPointer for Py2<'_, T> {
 ///
 /// The advantage of this over `&Py2` is that it avoids the need to have a pointer-to-pointer, as Py2
 /// is already a pointer to an `ffi::PyObject``.
+///
+/// Similarly, this type is `Copy` and `Clone`, like a shared reference (`&T`).
 #[repr(transparent)]
 pub(crate) struct Py2Borrowed<'a, 'py, T>(
     NonNull<ffi::PyObject>,
     PhantomData<&'a Py<T>>,
     Python<'py>,
 );
 
+impl<'py, T> Py2Borrowed<'_, 'py, T> {
+    /// Creates a new owned `Py2` from this borrowed reference by increasing the reference count.
+    pub(crate) fn to_owned(self) -> Py2<'py, T> {
+        unsafe { ffi::Py_INCREF(self.as_ptr()) };
+        Py2(
+            self.py(),
+            ManuallyDrop::new(unsafe { Py::from_non_null(self.0) }),
+        )
+    }
+}
+
 impl<'a, 'py> Py2Borrowed<'a, 'py, PyAny> {
     /// # Safety
     /// This is similar to `std::slice::from_raw_parts`, the lifetime `'a` is completely defined by
@@ -315,6 +328,14 @@ impl<'py, T> Deref for Py2Borrowed<'_, 'py, T> {
     }
 }
 
+impl<T> Clone for Py2Borrowed<'_, '_, T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<T> Copy for Py2Borrowed<'_, '_, T> {}
+
 /// A GIL-independent reference to an object allocated on the Python heap.
 ///
 /// This type does not auto-dereference to the inner object because you must prove you hold the GIL to access it.

src/prelude.rs

@@ -32,6 +32,7 @@ pub use crate::wrap_pyfunction;
 // pub(crate) use crate::types::bytes::PyBytesMethods;
 // pub(crate) use crate::types::dict::PyDictMethods;
 // pub(crate) use crate::types::float::PyFloatMethods;
+// pub(crate) use crate::types::list::PyListMethods;
 // pub(crate) use crate::types::mapping::PyMappingMethods;
 // pub(crate) use crate::types::sequence::PySequenceMethods;
 // pub(crate) use crate::types::string::PyStringMethods;

src/types/dict.rs

@@ -2,7 +2,7 @@ use super::PyMapping;
 use crate::err::{self, PyErr, PyResult};
 use crate::ffi::Py_ssize_t;
 use crate::ffi_ptr_ext::FfiPtrExt;
-use crate::instance::Py2;
+use crate::instance::{Py2, Py2Borrowed};
 use crate::py_result_ext::PyResultExt;
 use crate::types::any::PyAnyMethods;
 use crate::types::{PyAny, PyList};
@@ -406,7 +406,7 @@ impl<'py> PyDictMethods<'py> for Py2<'py, PyDict> {
             match unsafe {
                 ffi::PyDict_GetItemWithError(dict.as_ptr(), key.as_ptr())
                     .assume_borrowed_or_opt(py)
-                    .map(|borrowed_any| borrowed_any.clone())
+                    .map(Py2Borrowed::to_owned)
             } {
                 some @ Some(_) => Ok(some),
                 None => PyErr::take(py).map(Err).transpose(),
@@ -595,8 +595,8 @@ impl<'py> Iterator for PyDictIterator2<'py> {
             // - PyDict_Next returns borrowed values
             // - we have already checked that `PyDict_Next` succeeded, so we can assume these to be non-null
             Some((
-                unsafe { key.assume_borrowed_unchecked(py) }.clone(),
-                unsafe { value.assume_borrowed_unchecked(py) }.clone(),
+                unsafe { key.assume_borrowed_unchecked(py) }.to_owned(),
+                unsafe { value.assume_borrowed_unchecked(py) }.to_owned(),
             ))
         } else {
             None