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Running on Zero
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79d2392 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 | """The rule schema: what a San Francisco parking sign stack can say, as data.
Design notes:
- A pole holds a stack of Restriction objects (top to bottom matters for rendering,
not for semantics).
- Answering "can I park here at time T?" applies every restriction independently;
the most severe applicable verdict wins (TOW > NO_PARK > NO_STOP > TIME_LIMIT > FREE).
- v1 scope: sign-stack-only. Curb paint and meters are out of frame; queries that
depend on them must be answered ABSTAIN by a correct model.
"""
from __future__ import annotations
from dataclasses import dataclass, field
from datetime import datetime, time
from enum import Enum
class Day(Enum):
MON, TUE, WED, THU, FRI, SAT, SUN = range(7)
WEEKDAYS = frozenset({Day.MON, Day.TUE, Day.WED, Day.THU, Day.FRI})
EVERY_DAY = frozenset(Day)
class Kind(Enum):
NO_STOPPING = "no_stopping" # CA R26(S): no stopping at any time in window
NO_PARKING = "no_parking" # CA R26: no parking in window
TOW_AWAY = "tow_away" # modifier or standalone: violation = tow
TIME_LIMIT = "time_limit" # CA R30: e.g. 2-hour parking 9am-6pm
STREET_CLEANING = "street_cleaning" # CA R32: no parking, specific weekday window
PERMIT_EXEMPT_LIMIT = "permit_limit" # RPP: time limit EXCEPT vehicles with area permit
LOADING_ONLY = "loading_only" # passenger/commercial loading zone window
ANGLE_PARKING = "angle_parking" # informational: "PARK AT 90 DEGREES" etc. No verdict effect.
@dataclass(frozen=True)
class Window:
"""A recurring weekly time window, e.g. Tue 8:00-10:00."""
days: frozenset[Day]
start: time
end: time
weeks: frozenset[int] = frozenset() # which weeks of the month (1-5); empty = every week
def contains(self, dt: datetime) -> bool:
if Day(dt.weekday()) not in self.days or not (self.start <= dt.time() < self.end):
return False
if self.weeks: # "2nd & 4th Monday" style: nth occurrence of the weekday in the month
week_of_month = (dt.day - 1) // 7 + 1
if week_of_month not in self.weeks:
return False
return True
@dataclass(frozen=True)
class Restriction:
kind: Kind
window: Window
limit_minutes: int | None = None # TIME_LIMIT / PERMIT_EXEMPT_LIMIT
permit_area: str | None = None # RPP area letter, e.g. "S"
tow: bool = False # tow-away enforcement on violation
@dataclass
class SignStack:
"""Everything on one pole."""
restrictions: list[Restriction] = field(default_factory=list)
pole_id: str | None = None
class Verdict(Enum):
TOW_RISK = "tow_risk" # parking now risks a tow
NO = "no" # no parking (citation risk)
LIMITED = "limited" # ok up to N minutes
OK = "ok" # no restriction applies right now
ABSTAIN = "abstain" # not decidable from the sign stack alone
@dataclass
class Answer:
verdict: Verdict
limit_minutes: int | None = None # for LIMITED
until: datetime | None = None # next moment the verdict changes (v2)
reason: str = ""
SEVERITY = [Verdict.TOW_RISK, Verdict.NO, Verdict.LIMITED, Verdict.OK]
def can_park(stack: SignStack, when: datetime, permit_areas: frozenset[str] = frozenset()) -> Answer:
"""The resolver: ground truth for every generated question."""
verdicts: list[Answer] = []
for r in stack.restrictions:
if r.kind is Kind.ANGLE_PARKING:
continue # informational ("park at 90 degrees"), never affects the verdict
if not r.window.contains(when):
continue
if r.kind in (Kind.NO_STOPPING, Kind.NO_PARKING, Kind.STREET_CLEANING, Kind.LOADING_ONLY):
v = Verdict.TOW_RISK if (r.tow or r.kind is Kind.NO_STOPPING) else Verdict.NO
verdicts.append(Answer(v, reason=f"{r.kind.value} in effect"))
elif r.kind is Kind.TIME_LIMIT:
verdicts.append(Answer(Verdict.LIMITED, limit_minutes=r.limit_minutes,
reason=f"{r.limit_minutes}min limit"))
elif r.kind is Kind.PERMIT_EXEMPT_LIMIT:
# permit_area must be a hashable scalar; malformed model output (e.g. a list)
# is treated as "no matching permit"
if isinstance(r.permit_area, str) and r.permit_area in permit_areas:
verdicts.append(Answer(Verdict.OK, reason=f"permit {r.permit_area} exempts"))
else:
verdicts.append(Answer(Verdict.LIMITED, limit_minutes=r.limit_minutes,
reason=f"{r.limit_minutes}min limit without permit {r.permit_area}"))
if not verdicts:
return Answer(Verdict.OK, reason="no restriction in effect")
verdicts.sort(key=lambda a: SEVERITY.index(a.verdict))
best = verdicts[0]
if best.verdict is Verdict.LIMITED:
# multiple limits: strictest applies. Tolerate None (malformed model reads).
limits = [a.limit_minutes for a in verdicts
if a.verdict is Verdict.LIMITED and a.limit_minutes is not None]
best.limit_minutes = min(limits) if limits else None
return best
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