"""DateInterval.py
Convert interval strings (in the form of 1w2d, etc) to
seconds, and back again. Is not exactly about months or
years (leap years in particular).
Accepts (y)ear, (b)month, (w)eek, (d)ay, (h)our, (m)inute, (s)econd.
Exports only timeEncode and timeDecode functions.
"""
import re
second = 1
minute = second*60
hour = minute*60
day = hour*24
week = day*7
month = day*30
year = day*365
timeValues = {
'y': year,
'b': month,
'w': week,
'd': day,
'h': hour,
'm': minute,
's': second,
}
timeOrdered = timeValues.items()
timeOrdered.sort(lambda a, b: -cmp(a[1], b[1]))
def timeEncode(seconds):
"""Encode a number of seconds (representing a time interval).
Encode the number into a form like 1h2d3s.
"""
s = ''
for char, amount in timeOrdered:
if seconds >= amount:
i, seconds = divmod(seconds, amount)
s += '%i%s' % (i, char)
return s
_timeRE = re.compile(r'[0-9]+[a-zA-Z]')
def timeDecode(s):
"""Decode a number in the format 1h4d3m (1 hour, 3 days, 3 minutes).
Decode the format into a number of seconds.
"""
time = 0
for match in allMatches(s, _timeRE):
char = match.group(0)[-1].lower()
if not timeValues.has_key(char):
continue
time += int(match.group(0)[:-1]) * timeValues[char]
return time
def allMatches(source, regex):
"""Return a list of matches for regex in source."""
pos = 0
end = len(source)
rv = []
match = regex.search(source, pos)
while match:
rv.append(match)
match = regex.search(source, match.end())
return rv
__all__ = [timeEncode, timeDecode]