fixed lhs tuple assignments

Author: craigbarratt

custom_components/pyscript/eval.py

@@ -648,42 +648,53 @@ async def ast_nonlocal(self, arg):
             for var_name in arg.names:
                 self.curr_func.nonlocal_names.add(var_name)
 
-    async def ast_assign(self, arg):
-        """Execute assignment statement."""
-        val = await self.aeval(arg.value)
-        for lhs in arg.targets:  # pylint: disable=too-many-nested-blocks
-            if isinstance(lhs, ast.Subscript):
-                var = await self.aeval(lhs.value)
-                if isinstance(lhs.slice, ast.Index):
-                    ind = await self.aeval(lhs.slice.value)
-                    var[ind] = val
-                elif isinstance(lhs.slice, ast.Slice):
-                    lower = (
-                        await self.aeval(lhs.slice.lower) if lhs.slice.lower else None
-                    )
-                    upper = (
-                        await self.aeval(lhs.slice.upper) if lhs.slice.upper else None
-                    )
-                    step = await self.aeval(lhs.slice.step) if lhs.slice.step else None
-                    var[slice(lower, upper, step)] = val
+    async def recurse_assign(self, lhs, val):
+        """Recursive assignment."""
+        if isinstance(lhs, ast.Tuple):
+            try:
+                val_len = len(val)
+            except TypeError:
+                raise TypeError("cannot unpack non-iterable object")
+            if len(lhs.elts) < val_len:
+                raise ValueError(
+                    f"too many values to unpack (expected {len(lhs.elts)})"
+                )
+            if len(lhs.elts) > val_len:
+                raise ValueError(f"too few values to unpack (expected {len(lhs.elts)})")
+            for lhs_elt, val_elt in zip(lhs.elts, val):
+                await self.recurse_assign(lhs_elt, val_elt)
+        elif isinstance(lhs, ast.Subscript):
+            var = await self.aeval(lhs.value)
+            if isinstance(lhs.slice, ast.Index):
+                ind = await self.aeval(lhs.slice.value)
+                var[ind] = val
             else:
-                var_name = await self.aeval(lhs)
-                if var_name.find(".") >= 0:
-                    self.state.set(var_name, val)
-                else:
-                    if self.curr_func and var_name in self.curr_func.global_names:
-                        self.global_sym_table[var_name] = val
-                    elif self.curr_func and var_name in self.curr_func.nonlocal_names:
-                        for sym_table in reversed(self.sym_table_stack[1:]):
-                            if var_name in sym_table:
-                                sym_table[var_name] = val
-                                break
-                        else:
-                            raise TypeError(
-                                f"can't find nonlocal '{var_name}' for assignment"
-                            )
+                lower = await self.aeval(lhs.slice.lower) if lhs.slice.lower else None
+                upper = await self.aeval(lhs.slice.upper) if lhs.slice.upper else None
+                step = await self.aeval(lhs.slice.step) if lhs.slice.step else None
+                var[slice(lower, upper, step)] = val
+        else:
+            var_name = await self.aeval(lhs)
+            if var_name.find(".") >= 0:
+                self.state.set(var_name, val)
+            else:
+                if self.curr_func and var_name in self.curr_func.global_names:
+                    self.global_sym_table[var_name] = val
+                elif self.curr_func and var_name in self.curr_func.nonlocal_names:
+                    for sym_table in reversed(self.sym_table_stack[1:]):
+                        if var_name in sym_table:
+                            sym_table[var_name] = val
+                            break
                     else:
-                        self.sym_table[var_name] = val
+                        raise TypeError(
+                            f"can't find nonlocal '{var_name}' for assignment"
+                        )
+                else:
+                    self.sym_table[var_name] = val
+
+    async def ast_assign(self, arg):
+        """Execute assignment statement."""
+        await self.recurse_assign(arg.targets[0], await self.aeval(arg.value))
 
     async def ast_augassign(self, arg):
         """Execute augmented assignment statement (lhs <BinOp>= value)."""
@@ -991,8 +1002,7 @@ async def ast_list(self, arg):
 
     async def ast_tuple(self, arg):
         """Evaluate Tuple."""
-        if isinstance(arg.ctx, ast.Load):
-            return tuple(await self.eval_elt_list(arg.elts))
+        return tuple(await self.eval_elt_list(arg.elts))
 
     async def ast_dict(self, arg):
         """Evaluate dict."""

tests/custom_components/pyscript/test_unit_eval.py

@@ -138,6 +138,13 @@
         "z = [0, 1, 2, 3, 4, 5, 6, 7, 8]; z[::] = [10, 11, 12, 13, 14, 15, 16, 17]; z",
         [10, 11, 12, 13, 14, 15, 16, 17],
     ],
+    ["(x, y) = (1, 2); [x, y]", [1, 2]],
+    ["y = [1,2]; (x, y[0]) = (3, 4); [x, y]", [3, [4, 2]]],
+    ["((x, y), (z, t)) = ((1, 2), (3, 4)); [x, y, z, t]", [1, 2, 3, 4]],
+    [
+        "z = [1,2,3]; ((x, y), (z[2], t)) = ((1, 2), (20, 4)); [x, y, z, t]",
+        [1, 2, [1, 2, 20], 4],
+    ],
     ["eval('1+2')", 3],
     ["x = 5; eval('2 * x')", 10],
     ["x = 5; exec('x = 2 * x'); x", 10],
@@ -513,6 +520,18 @@ def test_eval(hass):
         "Exception in test line 1 column 2: unsupported operand type(s) for +: 'int' and 'str'",
     ],
     ["xx", "Exception in test line 1 column 0: name 'xx' is not defined"],
+    [
+        "(x, y) = (1, 2, 4)",
+        "Exception in test line 1 column 16: too many values to unpack (expected 2)",
+    ],
+    [
+        "(x, y, z) = (1, 2)",
+        "Exception in test line 1 column 16: too few values to unpack (expected 3)",
+    ],
+    [
+        "(x, y) = 1",
+        "Exception in test line 1 column 9: cannot unpack non-iterable object",
+    ],
     [
         "import math; math.sinXYZ",
         "Exception in test line 1 column 13: module 'math' has no attribute 'sinXYZ'",