tegwick
49de8d15b6
- .forgejo/workflows/test.yaml: offline tests on Python 3.10 and 3.13 - LICENSE: Target Revenue Source License V1C1 (org-wide preliminary licence) - pyproject: license field; AGENTS/SCOPE: CI and licence facts Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Assistant: claude-code Assistant-Model: opus Assistant-Process: 153021@bnt-lap001 Assistant-Session: 46917be4-6400-4106-b8b7-61953a0caf24
62 lines
2.5 KiB
Python
62 lines
2.5 KiB
Python
"""Period ordering for "latest value" selection.
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A source's period labels are only compared when they share one recognised
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format; mixed or unrecognised formats are an error, never a silent string
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comparison. Spec field `period_format` pins the format ("auto" by default);
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"string" opts in to plain lexicographic order.
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"""
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from __future__ import annotations
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import re
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from typing import Callable
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_FORMATS: dict[str, tuple[re.Pattern[str], Callable[[re.Match[str]], tuple[int, ...]]]] = {
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"year": (re.compile(r"^(\d{4})$"), lambda m: (int(m[1]),)),
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"month": (re.compile(r"^(\d{4})-(\d{2})$"), lambda m: (int(m[1]), int(m[2]))),
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"date": (re.compile(r"^(\d{4})-(\d{2})-(\d{2})$"), lambda m: (int(m[1]), int(m[2]), int(m[3]))),
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"quarter": (re.compile(r"^(\d{4})-?Q([1-4])$"), lambda m: (int(m[1]), int(m[2]))),
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"semester": (re.compile(r"^(\d{4})-?S([12])$"), lambda m: (int(m[1]), int(m[2]))),
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"week": (re.compile(r"^(\d{4})-?W(\d{2})$"), lambda m: (int(m[1]), int(m[2]))),
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# Fixed-width digit labels such as YYYYMM or Census BTOS YYYYPP.
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"digits": (re.compile(r"^(\d+)$"), lambda m: (len(m[1]), int(m[1]))),
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}
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class PeriodError(ValueError):
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pass
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def detect(label: str) -> str | None:
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label = label.strip()
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for name, (pat, _) in _FORMATS.items():
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if pat.match(label):
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return name
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return None
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def sort_key(label: str, fmt: str) -> tuple[int, ...] | str:
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if fmt == "string":
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return label
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pat, key = _FORMATS[fmt]
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m = pat.match(label.strip())
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if m is None:
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raise PeriodError(f"period {label!r} does not match format {fmt!r}")
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return key(m)
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def order(labels: list[str], fmt: str = "auto") -> tuple[str, list[str]]:
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"""Return (format, labels newest first). Raises PeriodError for mixed formats."""
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if fmt == "auto":
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found = {detect(lbl) for lbl in labels}
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if None in found:
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bad = [lbl for lbl in labels if detect(lbl) is None][:3]
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raise PeriodError(f"unrecognised period labels {bad}; set period_format")
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if len(found) > 1:
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raise PeriodError(f"mixed period formats {sorted(found)}; set period_format")
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fmt = found.pop() if found else "string"
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if fmt == "digits" and len({len(lbl.strip()) for lbl in labels}) > 1:
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raise PeriodError("digit period labels of different widths; set period_format")
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elif fmt != "string" and fmt not in _FORMATS:
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raise PeriodError(f"unknown period_format {fmt!r}")
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return fmt, sorted(labels, key=lambda lbl: sort_key(lbl, fmt), reverse=True)
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