pymethods: add support for inplace concat & repeat

guide/src/class/protocols.md

@@ -243,6 +243,18 @@ and `Return` a final value - see its docs for further details and an example.
     Used by the `*` operator, after trying the numeric multiplication via
     the `__mul__` and `__rmul__` methods.
 
+  * `fn __inplace_concat__(&self, other: impl FromPyObject) -> PyResult<impl ToPyObject>`
+
+    Concatenates two sequences.
+    Used by the `+=` operator, after trying the numeric addition via
+    the `__iadd__` method.
+
+  * `fn __inplace_repeat__(&self, count: isize) -> PyResult<impl ToPyObject>`
+
+    Concatenates two sequences.
+    Used by the `*=` operator, after trying the numeric multiplication via
+    the `__imul__` method.
+
 
 ### Descriptors
 

pyo3-macros-backend/src/pymethod.rs

@@ -53,6 +53,12 @@ impl PyMethodKind {
             "__contains__" => PyMethodKind::Proto(PyMethodProtoKind::Slot(&__CONTAINS__)),
             "__concat__" => PyMethodKind::Proto(PyMethodProtoKind::Slot(&__CONCAT__)),
             "__repeat__" => PyMethodKind::Proto(PyMethodProtoKind::Slot(&__REPEAT__)),
+            "__inplace_concat__" => {
+                PyMethodKind::Proto(PyMethodProtoKind::Slot(&__INPLACE_CONCAT__))
+            }
+            "__inplace_repeat__" => {
+                PyMethodKind::Proto(PyMethodProtoKind::Slot(&__INPLACE_REPEAT__))
+            }
             "__getitem__" => PyMethodKind::Proto(PyMethodProtoKind::Slot(&__GETITEM__)),
             "__pos__" => PyMethodKind::Proto(PyMethodProtoKind::Slot(&__POS__)),
             "__neg__" => PyMethodKind::Proto(PyMethodProtoKind::Slot(&__NEG__)),
@@ -606,6 +612,10 @@ const __CONTAINS__: SlotDef = SlotDef::new("Py_sq_contains", "objobjproc")
     .ret_ty(Ty::Int);
 const __CONCAT__: SlotDef = SlotDef::new("Py_sq_concat", "binaryfunc").arguments(&[Ty::Object]);
 const __REPEAT__: SlotDef = SlotDef::new("Py_sq_repeat", "ssizeargfunc").arguments(&[Ty::PySsizeT]);
+const __INPLACE_CONCAT__: SlotDef =
+    SlotDef::new("Py_sq_concat", "binaryfunc").arguments(&[Ty::Object]);
+const __INPLACE_REPEAT__: SlotDef =
+    SlotDef::new("Py_sq_repeat", "ssizeargfunc").arguments(&[Ty::PySsizeT]);
 const __GETITEM__: SlotDef = SlotDef::new("Py_mp_subscript", "binaryfunc").arguments(&[Ty::Object]);
 
 const __POS__: SlotDef = SlotDef::new("Py_nb_positive", "unaryfunc");

tests/test_sequence.rs

@@ -66,12 +66,17 @@ impl ByteSequence {
         }
     }
 
-    fn __concat__(&self, other: PyRef<Self>) -> Self {
+    fn __concat__(&self, other: &Self) -> Self {
         let mut elements = self.elements.clone();
         elements.extend_from_slice(&other.elements);
         Self { elements }
     }
 
+    fn __inplace_concat__(mut slf: PyRefMut<Self>, other: &Self) -> Py<Self> {
+        slf.elements.extend_from_slice(&other.elements);
+        slf.into()
+    }
+
     fn __repeat__(&self, count: isize) -> PyResult<Self> {
         if count >= 0 {
             let mut elements = Vec::with_capacity(self.elements.len() * count as usize);
@@ -83,6 +88,19 @@ impl ByteSequence {
             Err(PyValueError::new_err("invalid repeat count"))
         }
     }
+
+    fn __inplace_repeat__(mut slf: PyRefMut<Self>, count: isize) -> PyResult<Py<Self>> {
+        if count >= 0 {
+            let mut elements = Vec::with_capacity(slf.elements.len() * count as usize);
+            for _ in 0..count {
+                elements.extend(&slf.elements);
+            }
+            slf.elements = elements;
+            Ok(slf.into())
+        } else {
+            Err(PyValueError::new_err("invalid repeat count"))
+        }
+    }
 }
 
 /// Return a dict with `s = ByteSequence([1, 2, 3])`.