mirror of
https://github.com/zulip/zulip.git
synced 2025-11-04 05:53:43 +00:00
75 lines
1.5 KiB
Python
75 lines
1.5 KiB
Python
from collections.abc import Callable
|
|
from typing import Generic, TypeVar
|
|
|
|
"""
|
|
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.
|
|
"""
|
|
|
|
T = TypeVar("T")
|
|
|
|
|
|
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')
|
|
"""
|
|
seq_dict: 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
|
|
|
|
|
|
"""
|
|
NEXT_ID is a singleton used by an entire process, which is
|
|
almost always reasonable. If you want to have two parallel
|
|
sequences, just use different `name` values.
|
|
|
|
This object gets created once and only once during the first
|
|
import of the file.
|
|
"""
|
|
|
|
NEXT_ID = sequencer()
|
|
|
|
|
|
class IdMapper(Generic[T]):
|
|
def __init__(self) -> None:
|
|
self.map: dict[T, int] = {}
|
|
self.cnt = 0
|
|
|
|
def has(self, their_id: T) -> bool:
|
|
return their_id in self.map
|
|
|
|
def get(self, their_id: T) -> int:
|
|
if their_id in self.map:
|
|
return self.map[their_id]
|
|
|
|
self.cnt += 1
|
|
our_id = self.cnt
|
|
self.map[their_id] = our_id
|
|
return our_id
|