1c59f331f4
Option A (text-faithful): RateProblem gains time_unit (the duration's ORIGINAL unit; time stays int; defaults to the rate denominator). The SOLVER converts via convert_time -> exact Fraction -> int-or-refuse(non_integer); Fraction never leaves the solver, no floats. The reader accepts a convertible (minute<->hour) duration mismatch (keeps original time_unit); a non-convertible one still refuses rate_unit_mismatch. Signature includes time_unit ('30 minutes' != '30 hours').
Gold: r3-09 flips reader_refuses -> SOLVED (60 mph for 30 min = 30 mile, exact 1/2 hour; distractor 1800 rejected); new r3-13 non-convertible (3 gallons) stays rate_unit_mismatch. R3 gold 13/13; reader 9/0/0 -> answers 7/0/6 (setup_correct 8->9). Failure-family: rate_unit_mismatch now non-convertible-only -> still unsupported_rate_duration proposal surface; router-hygiene invariant stays green; R1 7/0/3, R2 10/0/0 unchanged. 119-test smoke green incl. invariants. Off-serving, no float path.
64 lines
2.9 KiB
Python
64 lines
2.9 KiB
Python
"""Exact integer single-rate solver (R3c) with exact-rational unit conversion (R3.2c).
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Solves the one unknown of a ``RateProblem`` — ``quantity = rate × time`` and its two inverses —
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normalizing the duration to the rate's denominator unit by **exact rational conversion** (R3.2):
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```text
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query quantity: quantity = rate × convert(time) (exact int or REFUSE)
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query rate: rate = quantity ÷ convert(time) (exact int or REFUSE)
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query time: time = quantity ÷ rate (in the rate denominator unit) (exact int or REFUSE)
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```
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``Fraction`` is confined here: ``convert_time`` returns an exact rational, the arithmetic is
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exact, and a non-whole result REFUSES (``non_integer_solution``) — **no float, no rounding**. A
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duration unit that does not convert to the rate denominator (``…/hour`` for ``3 gallons``) raises
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``ConversionError`` and REFUSES (``rate_unit_mismatch``). Off-serving; deterministic.
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"""
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from __future__ import annotations
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from fractions import Fraction
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from generate.meaning_graph.reader import Refusal
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from generate.rate_comprehension.conversion import ConversionError, convert_time
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from generate.rate_comprehension.model import RateProblem
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from generate.rate_comprehension.units import RateUnit
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def _exact_int(value: Fraction) -> int | Refusal:
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"""An exact integer, or a typed refusal — never a rounded/floored approximation."""
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if value.denominator != 1:
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return Refusal("non_integer_solution", str(value))
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return int(value)
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def solve_rate(problem: RateProblem) -> int | Refusal:
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"""Solve the unknown slot exactly (converting the duration as needed), or refuse."""
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ru = problem.rate_unit
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try:
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if problem.query == "quantity":
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assert problem.rate is not None and problem.time is not None
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time = convert_time(problem.time, problem.time_unit, ru.denominator)
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return _exact_int(Fraction(problem.rate) * time)
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if problem.query == "rate":
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assert problem.quantity is not None and problem.time is not None
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time = convert_time(problem.time, problem.time_unit, ru.denominator)
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return _exact_int(Fraction(problem.quantity) / time)
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# query == "time" — answered in the rate's denominator unit; the duration is the unknown.
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assert problem.quantity is not None and problem.rate is not None
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return _exact_int(Fraction(problem.quantity) / Fraction(problem.rate))
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except ConversionError as exc:
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return Refusal("rate_unit_mismatch", str(exc))
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def answer_unit(problem: RateProblem) -> str | RateUnit:
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"""The unit of the answer — the rate numerator (quantity), the rate denominator (time), or the
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full ``RateUnit`` (rate)."""
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if problem.query == "quantity":
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return problem.quantity_unit
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if problem.query == "time":
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return problem.rate_unit.denominator
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return problem.rate_unit
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__all__ = ["answer_unit", "solve_rate"]
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