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import re
from .. import info_variables, token_utils
from ..ft_gettext import current_lang
from ..message_parser import get_parser
from ..tb_data import TracebackData # for type checking only
from ..typing_info import CauseInfo # for type checking only
parser = get_parser(RuntimeError)
_ = current_lang.translate
@parser._add
def container_changed_size_during_iteration(
message: str, tb_data: TracebackData
) -> CauseInfo:
pattern = re.compile(r"(.*) changed size during iteration")
match = re.search(pattern, message)
if not match:
return {}
container_name = match[1].lower()
frame = tb_data.exception_frame
if container_name.startswith("dict"):
container_name = "dict"
obj_type = dict
elif container_name == "set":
obj_type = set
else:
return {}
container_type = info_variables.convert_type(container_name)
objects = info_variables.get_all_objects(tb_data.bad_line, frame)
names = []
for name, obj in objects["name, obj"]:
if isinstance(obj, obj_type):
names.append(name)
tokens = token_utils.tokenize(tb_data.bad_line)
loop_keywords = [tok.string for tok in tokens if tok.string in {"for", "while"}]
loop_keywords = set(loop_keywords)
if len(loop_keywords) == 1:
for_while = "for" if "for" in loop_keywords else "while"
else:
for_while = "for/while"
if len(names) == 1:
cause = _(
"While you were iterating over the items of `{name}` ({container_type})\n"
"in a `{for_while}` loop, you either tried to add or remove items from it.\n"
"Suggestion: start by making a copy of `{name}` and iterate over the items\n"
"of that copy if you want to change `{name}` inside a loop.\n"
"You might want to do this as follows:\n\n"
" my_{name} = {name}.copy()\n"
" for item in my_{name}:\n"
" # Change {name}\n"
).format(name=names[0], container_type=container_type, for_while=for_while)
else:
cause = _(
"While you were iterating over the items of a container ({container_type})\n"
"in a `{for_while}` loop, you either tried to add or remove items from it.\n"
"Suggestion: start by making a copy of the container and iterate over the items\n"
"of that copy if you want to change that container inside a loop.\n"
).format(container_type=container_type, for_while=for_while)
return {"cause": cause}
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