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"""Helpful functions used internally within arrow.""" |
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import datetime |
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from typing import Any, Optional, cast |
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from dateutil.rrule import WEEKLY, rrule |
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from arrow.constants import ( |
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MAX_ORDINAL, |
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MAX_TIMESTAMP, |
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MAX_TIMESTAMP_MS, |
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MAX_TIMESTAMP_US, |
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MIN_ORDINAL, |
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) |
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def next_weekday( |
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start_date: Optional[datetime.date], weekday: int |
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) -> datetime.datetime: |
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"""Get next weekday from the specified start date. |
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:param start_date: Datetime object representing the start date. |
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:param weekday: Next weekday to obtain. Can be a value between 0 (Monday) and 6 (Sunday). |
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:return: Datetime object corresponding to the next weekday after start_date. |
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Usage:: |
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# Get first Monday after epoch |
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>>> next_weekday(datetime(1970, 1, 1), 0) |
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1970-01-05 00:00:00 |
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# Get first Thursday after epoch |
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>>> next_weekday(datetime(1970, 1, 1), 3) |
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1970-01-01 00:00:00 |
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# Get first Sunday after epoch |
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>>> next_weekday(datetime(1970, 1, 1), 6) |
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1970-01-04 00:00:00 |
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""" |
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if weekday < 0 or weekday > 6: |
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raise ValueError("Weekday must be between 0 (Monday) and 6 (Sunday).") |
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return cast( |
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datetime.datetime, |
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rrule(freq=WEEKLY, dtstart=start_date, byweekday=weekday, count=1)[0], |
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) |
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def is_timestamp(value: Any) -> bool: |
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"""Check if value is a valid timestamp.""" |
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if isinstance(value, bool): |
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return False |
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if not isinstance(value, (int, float, str)): |
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return False |
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try: |
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float(value) |
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return True |
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except ValueError: |
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return False |
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def validate_ordinal(value: Any) -> None: |
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"""Raise an exception if value is an invalid Gregorian ordinal. |
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:param value: the input to be checked |
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""" |
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if isinstance(value, bool) or not isinstance(value, int): |
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raise TypeError(f"Ordinal must be an integer (got type {type(value)}).") |
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if not (MIN_ORDINAL <= value <= MAX_ORDINAL): |
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raise ValueError(f"Ordinal {value} is out of range.") |
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def normalize_timestamp(timestamp: float) -> float: |
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"""Normalize millisecond and microsecond timestamps into normal timestamps.""" |
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if timestamp > MAX_TIMESTAMP: |
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if timestamp < MAX_TIMESTAMP_MS: |
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timestamp /= 1000 |
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elif timestamp < MAX_TIMESTAMP_US: |
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timestamp /= 1_000_000 |
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else: |
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raise ValueError(f"The specified timestamp {timestamp!r} is too large.") |
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return timestamp |
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def iso_to_gregorian(iso_year: int, iso_week: int, iso_day: int) -> datetime.date: |
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"""Converts an ISO week date into a datetime object. |
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:param iso_year: the year |
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:param iso_week: the week number, each year has either 52 or 53 weeks |
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:param iso_day: the day numbered 1 through 7, beginning with Monday |
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""" |
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if not 1 <= iso_week <= 53: |
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raise ValueError("ISO Calendar week value must be between 1-53.") |
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if not 1 <= iso_day <= 7: |
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raise ValueError("ISO Calendar day value must be between 1-7") |
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fourth_jan = datetime.date(iso_year, 1, 4) |
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delta = datetime.timedelta(fourth_jan.isoweekday() - 1) |
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year_start = fourth_jan - delta |
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gregorian = year_start + datetime.timedelta(days=iso_day - 1, weeks=iso_week - 1) |
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return gregorian |
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def validate_bounds(bounds: str) -> None: |
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if bounds != "()" and bounds != "(]" and bounds != "[)" and bounds != "[]": |
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raise ValueError( |
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"Invalid bounds. Please select between '()', '(]', '[)', or '[]'." |
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) |
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__all__ = ["next_weekday", "is_timestamp", "validate_ordinal", "iso_to_gregorian"] |
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