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5b76e0f | 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 | import re
_match_duration = re.compile(r"^(-?\d+\.?\d*)(s|ms)$").match
class DurationError(Exception):
"""
Exception indicating a general issue with a CSS duration.
"""
class DurationParseError(DurationError):
"""
Indicates a malformed duration string that could not be parsed.
"""
def _duration_as_seconds(duration: str) -> float:
"""
Args:
duration (str): A string of the form ``"2s"`` or ``"300ms"``, representing 2 seconds and
300 milliseconds respectively. If no unit is supplied, e.g. ``"2"``, then the duration is
assumed to be in seconds.
Raises:
DurationParseError: If the argument ``duration`` is not a valid duration string.
Returns:
float: The duration in seconds.
"""
match = _match_duration(duration)
if match:
value, unit_name = match.groups()
value = float(value)
if unit_name == "ms":
duration_secs = value / 1000
else:
duration_secs = value
else:
try:
duration_secs = float(duration)
except ValueError:
raise DurationParseError(
f"{duration!r} is not a valid duration."
) from ValueError
return duration_secs
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