added *target tuple assignment

Author: craigbarratt

custom_components/pyscript/eval.py

@@ -611,15 +611,31 @@ async def recurse_assign(self, lhs, val):
             except AttributeError:
                 raise TypeError("cannot unpack non-iterable object")
             sentinel = object()
-            for lhs_elt in lhs.elts:
+            for lhs_idx, lhs_elt in enumerate(lhs.elts):
                 val_elt = next(val_iter, sentinel)
                 if val_elt is sentinel:
-                    raise TypeError(
+                    raise ValueError(
                         f"too few values to unpack (expected {len(lhs.elts)})"
                     )
+                if isinstance(lhs_elt, ast.Starred):
+                    star_lhs = [val_elt, *val_iter]
+                    star_len = len(star_lhs) - (len(lhs.elts) - lhs_idx - 1)
+                    if star_len < 0:
+                        raise ValueError(
+                            f"too few values to unpack (expected at least {len(lhs.elts) - 1})"
+                        )
+                    star_name = lhs_elt.value.id
+                    for lhs_idx, lhs_elt in enumerate(lhs.elts[lhs_idx + 1 :]):
+                        await self.recurse_assign(lhs_elt, star_lhs[star_len + lhs_idx])
+                    await self.recurse_assign(
+                        ast.Name(id=star_name, ctx=ast.Store()), star_lhs[0:star_len]
+                    )
+                    return
                 await self.recurse_assign(lhs_elt, val_elt)
             if next(val_iter, sentinel) is not sentinel:
-                raise TypeError(f"too many values to unpack (expected {len(lhs.elts)})")
+                raise ValueError(
+                    f"too many values to unpack (expected {len(lhs.elts)})"
+                )
         elif isinstance(lhs, ast.Subscript):
             var = await self.aeval(lhs.value)
             if isinstance(lhs.slice, ast.Index):

tests/custom_components/pyscript/test_unit_eval.py

@@ -153,6 +153,10 @@
         "tuples = [(1, 2), (3, 4), (5, 6)]; a, b = zip(*tuples); [a, b]",
         [(1, 3, 5), (2, 4, 6)],
     ],
+    ["a, *y, w, z = range(3); [a, y, w, z]", [0, [], 1, 2]],
+    ["a, *y, w, z = range(4); [a, y, w, z]", [0, [1], 2, 3]],
+    ["a, *y, w, z = range(6); [a, y, w, z]", [0, [1, 2, 3], 4, 5]],
+    ["x = [0, 1]; i = 0; i, x[i] = 1, 2; [i, x]", [1, [0, 2]]],
     ["Foo = type('Foo', (), {'x': 100}); Foo.x = 10; Foo.x", 10],
     ["Foo = type('Foo', (), {'x': 100}); Foo.x += 10; Foo.x", 110],
     ["Foo = [type('Foo', (), {'x': 100})]; Foo[0].x = 10; Foo[0].x", 10],
@@ -698,6 +702,10 @@ def test_eval(hass):
         "(x, y) = 1",
         "Exception in test line 1 column 9: cannot unpack non-iterable object",
     ],
+    [
+        "a, *y, w, z = range(2)",
+        "Exception in test line 1 column 0: too few values to unpack (expected at least 3)",
+    ],
     [
         "assert 1 == 0, 'this is an error'",
         "Exception in test line 1 column 15: this is an error",