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Merged
serhiy-storchaka merged 1 commit into from
Mar 5, 2019
Merged

bpo-36187: Remove NamedStore. #12167

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2 changes: 1 addition & 1 deletion Include/Python-ast.h
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4 changes: 4 additions & 0 deletions Lib/test/test_syntax.py
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,10 @@
Traceback (most recent call last):
SyntaxError: cannot assign to True

>>> (True := 1)
Traceback (most recent call last):
SyntaxError: cannot use named assignment with True

>>> obj.__debug__ = 1
Traceback (most recent call last):
SyntaxError: cannot assign to __debug__
Expand Down
2 changes: 1 addition & 1 deletion Parser/Python.asdl
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Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,7 @@ module Python
-- col_offset is the byte offset in the utf8 string the parser uses
attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)

expr_context = Load | Store | Del | AugLoad | AugStore | Param | NamedStore
expr_context = Load | Store | Del | AugLoad | AugStore | Param

slice = Slice(expr? lower, expr? upper, expr? step)
| ExtSlice(slice* dims)
Expand Down
21 changes: 1 addition & 20 deletions Python/Python-ast.c
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199 changes: 90 additions & 109 deletions Python/ast.c
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Original file line number Diff line number Diff line change
Expand Up @@ -94,8 +94,6 @@ expr_context_name(expr_context_ty ctx)
return "Load";
case Store:
return "Store";
case NamedStore:
return "NamedStore";
case Del:
return "Del";
case AugLoad:
Expand Down Expand Up @@ -1029,6 +1027,80 @@ copy_location(expr_ty e, const node *n)
return e;
}

static const char *
get_expr_name(expr_ty e)
{
switch (e->kind) {
case Attribute_kind:
return "attribute";
case Subscript_kind:
return "subscript";
case Starred_kind:
return "starred";
case Name_kind:
return "name";
case List_kind:
return "list";
case Tuple_kind:
return "tuple";
case Lambda_kind:
return "lambda";
case Call_kind:
return "function call";
case BoolOp_kind:
case BinOp_kind:
case UnaryOp_kind:
return "operator";
case GeneratorExp_kind:
return "generator expression";
case Yield_kind:
case YieldFrom_kind:
return "yield expression";
case Await_kind:
return "await expression";
case ListComp_kind:
return "list comprehension";
case SetComp_kind:
return "set comprehension";
case DictComp_kind:
return "dict comprehension";
case Dict_kind:
return "dict display";
case Set_kind:
return "set display";
case JoinedStr_kind:
case FormattedValue_kind:
return "f-string expression";
case Constant_kind: {
PyObject *value = e->v.Constant.value;
if (value == Py_None) {
return "None";
}
if (value == Py_False) {
return "False";
}
if (value == Py_True) {
return "True";
}
if (value == Py_Ellipsis) {
return "Ellipsis";
}
return "literal";
}
case Compare_kind:
return "comparison";
case IfExp_kind:
return "conditional expression";
case NamedExpr_kind:
return "named expression";
default:
PyErr_Format(PyExc_SystemError,
"unexpected expression in assignment %d (line %d)",
e->kind, e->lineno);
return NULL;
}
}

/* Set the context ctx for expr_ty e, recursively traversing e.

Only sets context for expr kinds that "can appear in assignment context"
Expand All @@ -1040,10 +1112,6 @@ static int
set_context(struct compiling *c, expr_ty e, expr_context_ty ctx, const node *n)
{
asdl_seq *s = NULL;
/* If a particular expression type can't be used for assign / delete,
set expr_name to its name and an error message will be generated.
*/
const char* expr_name = NULL;

/* The ast defines augmented store and load contexts, but the
implementation here doesn't actually use them. The code may be
Expand All @@ -1056,136 +1124,41 @@ set_context(struct compiling *c, expr_ty e, expr_context_ty ctx, const node *n)

switch (e->kind) {
case Attribute_kind:
if (ctx == NamedStore) {
expr_name = "attribute";
break;
}

e->v.Attribute.ctx = ctx;
if (ctx == Store && forbidden_name(c, e->v.Attribute.attr, n, 1))
return 0;
break;
case Subscript_kind:
if (ctx == NamedStore) {
expr_name = "subscript";
break;
}

e->v.Subscript.ctx = ctx;
break;
case Starred_kind:
if (ctx == NamedStore) {
expr_name = "starred";
break;
}

e->v.Starred.ctx = ctx;
if (!set_context(c, e->v.Starred.value, ctx, n))
return 0;
break;
case Name_kind:
if (ctx == Store || ctx == NamedStore) {
if (ctx == Store) {
if (forbidden_name(c, e->v.Name.id, n, 0))
return 0; /* forbidden_name() calls ast_error() */
}
e->v.Name.ctx = ctx;
break;
case List_kind:
if (ctx == NamedStore) {
expr_name = "list";
break;
}

e->v.List.ctx = ctx;
s = e->v.List.elts;
break;
case Tuple_kind:
if (ctx == NamedStore) {
expr_name = "tuple";
break;
}

e->v.Tuple.ctx = ctx;
s = e->v.Tuple.elts;
break;
case Lambda_kind:
expr_name = "lambda";
break;
case Call_kind:
expr_name = "function call";
break;
case BoolOp_kind:
case BinOp_kind:
case UnaryOp_kind:
expr_name = "operator";
break;
case GeneratorExp_kind:
expr_name = "generator expression";
break;
case Yield_kind:
case YieldFrom_kind:
expr_name = "yield expression";
break;
case Await_kind:
expr_name = "await expression";
break;
case ListComp_kind:
expr_name = "list comprehension";
break;
case SetComp_kind:
expr_name = "set comprehension";
break;
case DictComp_kind:
expr_name = "dict comprehension";
break;
case Dict_kind:
expr_name = "dict display";
break;
case Set_kind:
expr_name = "set display";
break;
case JoinedStr_kind:
case FormattedValue_kind:
expr_name = "f-string expression";
break;
case Constant_kind: {
PyObject *value = e->v.Constant.value;
if (value == Py_None || value == Py_False || value == Py_True
|| value == Py_Ellipsis)
{
return ast_error(c, n, "cannot %s %R",
ctx == Store ? "assign to" : "delete",
value);
default: {
const char *expr_name = get_expr_name(e);
if (expr_name != NULL) {
ast_error(c, n, "cannot %s %s",
ctx == Store ? "assign to" : "delete",
expr_name);
}
expr_name = "literal";
break;
}
case Compare_kind:
expr_name = "comparison";
break;
case IfExp_kind:
expr_name = "conditional expression";
break;
case NamedExpr_kind:
expr_name = "named expression";
break;
default:
PyErr_Format(PyExc_SystemError,
"unexpected expression in %sassignment %d (line %d)",
ctx == NamedStore ? "named ": "",
e->kind, e->lineno);
return 0;
}
/* Check for error string set by switch */
if (expr_name) {
if (ctx == NamedStore) {
return ast_error(c, n, "cannot use named assignment with %s",
expr_name);
}
else {
return ast_error(c, n, "cannot %s %s",
ctx == Store ? "assign to" : "delete",
expr_name);
}
}

Expand Down Expand Up @@ -1895,7 +1868,15 @@ ast_for_namedexpr(struct compiling *c, const node *n)
if (!value)
return NULL;

if (!set_context(c, target, NamedStore, n))
if (target->kind != Name_kind) {
const char *expr_name = get_expr_name(target);
if (expr_name != NULL) {
ast_error(c, n, "cannot use named assignment with %s", expr_name);
}
return NULL;
}

if (!set_context(c, target, Store, n))
return NULL;

return NamedExpr(target, value, LINENO(n), n->n_col_offset, n->n_end_lineno,
Expand Down
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