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# -*- coding: utf-8 -*-
# Copyright (c) 2014, Brandon Nielsen
# All rights reserved.
#
# This software may be modified and distributed under the terms
# of the BSD license. See the LICENSE file for details.
import datetime
import dateutil.relativedelta
from aniso8601.date import parse_date
from aniso8601.time import parse_time
from aniso8601 import compat
def parse_duration(isodurationstr, relative=False):
#Given a string representing an ISO 8601 duration, return a
#datetime.timedelta (or dateutil.relativedelta.relativedelta
#if relative=True) that matches the given duration. Valid formats are:
#
#PnYnMnDTnHnMnS (or any reduced precision equivalent)
#P<date>T<time>
if isodurationstr[0] != 'P':
raise ValueError('String is not a valid ISO8601 duration.')
#If Y, M, D, H, or S are in the string, assume it is a specified duration
if isodurationstr.find('Y') != -1 or isodurationstr.find('M') != -1 or isodurationstr.find('W') != -1 or isodurationstr.find('D') != -1 or isodurationstr.find('H') != -1 or isodurationstr.find('S') != -1:
return _parse_duration_prescribed(isodurationstr, relative)
else:
return _parse_duration_combined(isodurationstr, relative)
def _parse_duration_prescribed(durationstr, relative):
#durationstr can be of the form PnYnMnDTnHnMnS or PnW
#Make sure only the lowest order element has decimal precision
if durationstr.count('.') > 1:
raise ValueError('String is not a valid ISO8601 duration.')
elif durationstr.count('.') == 1:
#There should only ever be 1 letter after a decimal if there is more
#then one, the string is invalid
lettercount = 0;
for character in durationstr.split('.')[1]:
if character.isalpha() == True:
lettercount += 1
if lettercount > 1:
raise ValueError('String is not a valid ISO8601 duration.')
#Parse the elements of the duration
if durationstr.find('T') == -1:
if durationstr.find('Y') != -1:
years = _parse_duration_element(durationstr, 'Y')
else:
years = 0
if durationstr.find('M') != -1:
months = _parse_duration_element(durationstr, 'M')
else:
months = 0
if durationstr.find('W') != -1:
weeks = _parse_duration_element(durationstr, 'W')
else:
weeks = 0
if durationstr.find('D') != -1:
days = _parse_duration_element(durationstr, 'D')
else:
days = 0
#No hours, minutes or seconds
hours = 0
minutes = 0
seconds = 0
else:
firsthalf = durationstr[:durationstr.find('T')]
secondhalf = durationstr[durationstr.find('T'):]
if firsthalf.find('Y') != -1:
years = _parse_duration_element(firsthalf, 'Y')
else:
years = 0
if firsthalf.find('M') != -1:
months = _parse_duration_element(firsthalf, 'M')
else:
months = 0
if durationstr.find('W') != -1:
weeks = _parse_duration_element(durationstr, 'W')
else:
weeks = 0
if firsthalf.find('D') != -1:
days = _parse_duration_element(firsthalf, 'D')
else:
days = 0
if secondhalf.find('H') != -1:
hours = _parse_duration_element(secondhalf, 'H')
else:
hours = 0
if secondhalf.find('M') != -1:
minutes = _parse_duration_element(secondhalf, 'M')
else:
minutes = 0
if secondhalf.find('S') != -1:
seconds = _parse_duration_element(secondhalf, 'S')
else:
seconds = 0
if relative == True:
if int(years) != years or int(months) != months:
#https://github.com/dateutil/dateutil/issues/40
raise ValueError('Fractional months and years are not defined for relative intervals.')
return dateutil.relativedelta.relativedelta(years=int(years), months=int(months), weeks=weeks, days=days, hours=hours, minutes=minutes, seconds=seconds)
else:
#Note that weeks can be handled without conversion to days
totaldays = years * 365 + months * 30 + days
return datetime.timedelta(weeks=weeks, days=totaldays, hours=hours, minutes=minutes, seconds=seconds)
def _parse_duration_combined(durationstr, relative):
#Period of the form P<date>T<time>
#Split the string in to its component parts
datepart, timepart = durationstr[1:].split('T') #We skip the 'P'
datevalue = parse_date(datepart)
timevalue = parse_time(timepart)
if relative == True:
return dateutil.relativedelta.relativedelta(years=datevalue.year, months=datevalue.month, days=datevalue.day, hours=timevalue.hour, minutes=timevalue.minute, seconds=timevalue.second, microseconds=timevalue.microsecond)
else:
totaldays = datevalue.year * 365 + datevalue.month * 30 + datevalue.day
return datetime.timedelta(days=totaldays, hours=timevalue.hour, minutes=timevalue.minute, seconds=timevalue.second, microseconds=timevalue.microsecond)
def _parse_duration_element(durationstr, elementstr):
#Extracts the specified portion of a duration, for instance, given:
#durationstr = 'T4H5M6.1234S'
#elementstr = 'H'
#
#returns 4
#
#Note that the string must start with a character, so its assumed the
#full duration string would be split at the 'T'
durationstartindex = 0
durationendindex = durationstr.find(elementstr)
for characterindex in compat.range(durationendindex - 1, 0, -1):
if durationstr[characterindex].isalpha() == True:
durationstartindex = characterindex
break
durationstartindex += 1
if ',' in durationstr:
#Replace the comma with a 'full-stop'
durationstr = durationstr.replace(',', '.')
return float(durationstr[durationstartindex:durationendindex])
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