zulip/zerver/data_import/sequencer.py

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from typing import Callable, Dict
'''
This module helps you set up a bunch
of sequences, similar to how database
sequences work.
You need to be a bit careful here, since
you're dealing with a big singleton, but
for data imports that's usually easy to
manage. See hipchat.py for example usage.
'''
def _seq() -> Callable[[], int]:
i = 0
def next_one() -> int:
nonlocal i
i += 1
return i
return next_one
def sequencer() -> Callable[[str], int]:
'''
Use like this:
NEXT_ID = sequencer()
message_id = NEXT_ID('message_id')
'''
seq_dict = dict() # type: Dict[str, Callable[[], int]]
def next_one(name: str) -> int:
if name not in seq_dict:
seq_dict[name] = _seq()
seq = seq_dict[name]
return seq()
return next_one