Merge pull request #118 from crusaderky/simple_at

src/array_api_extra/_lib/_at.py

@@ -185,22 +185,42 @@ def __getitem__(self, idx: Index, /) -> at:  # numpydoc ignore=PR01,RT01
             raise ValueError(msg)
         return at(self._x, idx)
 
-    def _update_common(
+    def _op(
         self,
         at_op: _AtOp,
-        y: Array,
+        in_place_op: Callable[[Array, Array | object], Array] | None,
+        y: Array | object,
         /,
         copy: bool | None,
         xp: ModuleType | None,
-    ) -> tuple[Array, None] | tuple[None, Array]:  # numpydoc ignore=PR01
+    ) -> Array:
         """
-        Perform common prepocessing to all update operations.
+        Implement all update operations.
+
+        Parameters
+        ----------
+        at_op : _AtOp
+            Method of JAX's Array.at[].
+        in_place_op : Callable[[Array, Array | object], Array] | None
+            In-place operation to apply on mutable backends::
+
+                x[idx] = in_place_op(x[idx], y)
+
+            If None::
+
+                x[idx] = y
+
+        y : array or object
+            Right-hand side of the operation.
+        copy : bool or None
+            Whether to copy the input array. See the class docstring for details.
+        xp : array_namespace or None
+            The array namespace for the input array.
 
         Returns
         -------
-        tuple
-            If the operation can be resolved by ``at[]``, ``(return value, None)``
-            Otherwise, ``(None, preprocessed x)``.
+        Array
+            Updated `x`.
         """
         x, idx = self._x, self._idx
 
@@ -231,7 +251,7 @@ def _update_common(
             if is_jax_array(x):
                 # Use JAX's at[]
                 func = cast(Callable[[Array], Array], getattr(x.at[idx], at_op.value))
-                return func(y), None
+                return func(y)
             # Emulate at[] behaviour for non-JAX arrays
             # with a copy followed by an update
             if xp is None:
@@ -249,52 +269,25 @@ def _update_common(
             msg = f"Can't update read-only array {x}"
             raise ValueError(msg)
 
-        return None, x
+        if in_place_op:
+            x[self._idx] = in_place_op(x[self._idx], y)
+        else:  # set()
+            x[self._idx] = y
+        return x
 
     def set(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
     ) -> Array:  # numpydoc ignore=PR01,RT01
         """Apply ``x[idx] = y`` and return the update array."""
-        res, x = self._update_common(_AtOp.SET, y, copy=copy, xp=xp)
-        if res is not None:
-            return res
-        assert x is not None
-        x[self._idx] = y
-        return x
-
-    def _iop(
-        self,
-        at_op: _AtOp,
-        elwise_op: Callable[[Array, Array], Array],
-        y: Array,
-        /,
-        copy: bool | None,
-        xp: ModuleType | None,
-    ) -> Array:  # numpydoc ignore=PR01,RT01
-        """
-        ``x[idx] += y`` or equivalent in-place operation on a subset of x.
-
-        which is the same as saying
-            x[idx] = x[idx] + y
-        Note that this is not the same as
-            operator.iadd(x[idx], y)
-        Consider for example when x is a numpy array and idx is a fancy index, which
-        triggers a deep copy on __getitem__.
-        """
-        res, x = self._update_common(at_op, y, copy=copy, xp=xp)
-        if res is not None:
-            return res
-        assert x is not None
-        x[self._idx] = elwise_op(x[self._idx], y)
-        return x
+        return self._op(_AtOp.SET, None, y, copy=copy, xp=xp)
 
     def add(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
@@ -304,70 +297,68 @@ def add(
         # Note for this and all other methods based on _iop:
         # operator.iadd and operator.add subtly differ in behaviour, as
         # only iadd will trigger exceptions when y has an incompatible dtype.
-        return self._iop(_AtOp.ADD, operator.iadd, y, copy=copy, xp=xp)
+        return self._op(_AtOp.ADD, operator.iadd, y, copy=copy, xp=xp)
 
     def subtract(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
     ) -> Array:  # numpydoc ignore=PR01,RT01
         """Apply ``x[idx] -= y`` and return the updated array."""
-        return self._iop(_AtOp.SUBTRACT, operator.isub, y, copy=copy, xp=xp)
+        return self._op(_AtOp.SUBTRACT, operator.isub, y, copy=copy, xp=xp)
 
     def multiply(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
     ) -> Array:  # numpydoc ignore=PR01,RT01
         """Apply ``x[idx] *= y`` and return the updated array."""
-        return self._iop(_AtOp.MULTIPLY, operator.imul, y, copy=copy, xp=xp)
+        return self._op(_AtOp.MULTIPLY, operator.imul, y, copy=copy, xp=xp)
 
     def divide(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
     ) -> Array:  # numpydoc ignore=PR01,RT01
         """Apply ``x[idx] /= y`` and return the updated array."""
-        return self._iop(_AtOp.DIVIDE, operator.itruediv, y, copy=copy, xp=xp)
+        return self._op(_AtOp.DIVIDE, operator.itruediv, y, copy=copy, xp=xp)
 
     def power(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
     ) -> Array:  # numpydoc ignore=PR01,RT01
         """Apply ``x[idx] **= y`` and return the updated array."""
-        return self._iop(_AtOp.POWER, operator.ipow, y, copy=copy, xp=xp)
+        return self._op(_AtOp.POWER, operator.ipow, y, copy=copy, xp=xp)
 
     def min(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
     ) -> Array:  # numpydoc ignore=PR01,RT01
         """Apply ``x[idx] = minimum(x[idx], y)`` and return the updated array."""
-        if xp is None:
-            xp = array_namespace(self._x)
+        xp = array_namespace(self._x) if xp is None else xp
         y = xp.asarray(y)
-        return self._iop(_AtOp.MIN, xp.minimum, y, copy=copy, xp=xp)
+        return self._op(_AtOp.MIN, xp.minimum, y, copy=copy, xp=xp)
 
     def max(
         self,
-        y: Array,
+        y: Array | object,
         /,
         copy: bool | None = None,
         xp: ModuleType | None = None,
     ) -> Array:  # numpydoc ignore=PR01,RT01
         """Apply ``x[idx] = maximum(x[idx], y)`` and return the updated array."""
-        if xp is None:
-            xp = array_namespace(self._x)
+        xp = array_namespace(self._x) if xp is None else xp
         y = xp.asarray(y)
-        return self._iop(_AtOp.MAX, xp.maximum, y, copy=copy, xp=xp)
+        return self._op(_AtOp.MAX, xp.maximum, y, copy=copy, xp=xp)