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Diffstat (limited to 'tablib/packages/xlrd3/xldate.py')
| -rw-r--r-- | tablib/packages/xlrd3/xldate.py | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/tablib/packages/xlrd3/xldate.py b/tablib/packages/xlrd3/xldate.py new file mode 100644 index 0000000..634709d --- /dev/null +++ b/tablib/packages/xlrd3/xldate.py @@ -0,0 +1,167 @@ +# No part of the content of this file was derived from the works of David Giffin.
+#
+# Copyright © 2005-2008 Stephen John Machin, Lingfo Pty Ltd
+# This module is part of the xlrd3 package, which is released under a
+# BSD-style licence.
+#
+# Provides function(s) for dealing with Microsoft Excel ™ dates.
+#
+# 2008-10-18 SJM Fix bug in xldate_from_date_tuple (affected some years after 2099)
+#
+# The conversion from days to (year, month, day) starts with
+# an integral "julian day number" aka JDN.
+# FWIW, JDN 0 corresponds to noon on Monday November 24 in Gregorian year -4713.
+# More importantly:
+# Noon on Gregorian 1900-03-01 (day 61 in the 1900-based system) is JDN 2415080.0
+# Noon on Gregorian 1904-01-02 (day 1 in the 1904-based system) is JDN 2416482.0
+
+def ifd(x, y):
+ return divmod(x, y)[0]
+
+_JDN_delta = (2415080 - 61, 2416482 - 1)
+assert _JDN_delta[1] - _JDN_delta[0] == 1462
+
+class XLDateError(ValueError): pass
+
+class XLDateNegative(XLDateError): pass
+class XLDateAmbiguous(XLDateError): pass
+class XLDateTooLarge(XLDateError): pass
+class XLDateBadDatemode(XLDateError): pass
+class XLDateBadTuple(XLDateError): pass
+
+_XLDAYS_TOO_LARGE = (2958466, 2958466 - 1462) # This is equivalent to 10000-01-01
+
+# Convert an Excel number (presumed to represent a date, a datetime or a time) into
+# a tuple suitable for feeding to datetime or mx.DateTime constructors.
+# @param xldate The Excel number
+# @param datemode 0: 1900-based, 1: 1904-based.
+# <br>WARNING: when using this function to
+# interpret the contents of a workbook, you should pass in the Book.datemode
+# attribute of that workbook. Whether
+# the workbook has ever been anywhere near a Macintosh is irrelevant.
+# @return Gregorian (year, month, day, hour, minute, nearest_second).
+# <br>Special case: if 0.0 <= xldate < 1.0, it is assumed to represent a time;
+# (0, 0, 0, hour, minute, second) will be returned.
+# <br>Note: 1904-01-01 is not regarded as a valid date in the datemode 1 system; its "serial number"
+# is zero.
+# @throws XLDateNegative xldate < 0.00
+# @throws XLDateAmbiguous The 1900 leap-year problem (datemode == 0 and 1.0 <= xldate < 61.0)
+# @throws XLDateTooLarge Gregorian year 10000 or later
+# @throws XLDateBadDatemode datemode arg is neither 0 nor 1
+# @throws XLDateError Covers the 4 specific errors
+
+def xldate_as_tuple(xldate, datemode):
+ if datemode not in (0, 1):
+ raise XLDateBadDatemode(datemode)
+ if xldate == 0.00:
+ return (0, 0, 0, 0, 0, 0)
+ if xldate < 0.00:
+ raise XLDateNegative(xldate)
+ xldays = int(xldate)
+ frac = xldate - xldays
+ seconds = int(round(frac * 86400.0))
+ assert 0 <= seconds <= 86400
+ if seconds == 86400:
+ hour = minute = second = 0
+ xldays += 1
+ else:
+ # second = seconds % 60; minutes = seconds // 60
+ minutes, second = divmod(seconds, 60)
+ # minute = minutes % 60; hour = minutes // 60
+ hour, minute = divmod(minutes, 60)
+ if xldays >= _XLDAYS_TOO_LARGE[datemode]:
+ raise XLDateTooLarge(xldate)
+
+ if xldays == 0:
+ return (0, 0, 0, hour, minute, second)
+
+ if xldays < 61 and datemode == 0:
+ raise XLDateAmbiguous(xldate)
+
+ jdn = xldays + _JDN_delta[datemode]
+ yreg = (ifd(ifd(jdn * 4 + 274277, 146097) * 3, 4) + jdn + 1363) * 4 + 3
+ mp = ifd(yreg % 1461, 4) * 535 + 333
+ d = ifd(mp % 16384, 535) + 1
+ # mp /= 16384
+ mp >>= 14
+ if mp >= 10:
+ return (ifd(yreg, 1461) - 4715, mp - 9, d, hour, minute, second)
+ else:
+ return (ifd(yreg, 1461) - 4716, mp + 3, d, hour, minute, second)
+
+# === conversions from date/time to xl numbers
+
+def _leap(y):
+ if y % 4: return 0
+ if y % 100: return 1
+ if y % 400: return 0
+ return 1
+
+_days_in_month = (None, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
+
+# Convert a date tuple (year, month, day) to an Excel date.
+# @param year Gregorian year.
+# @param month 1 <= month <= 12
+# @param day 1 <= day <= last day of that (year, month)
+# @param datemode 0: 1900-based, 1: 1904-based.
+# @throws XLDateAmbiguous The 1900 leap-year problem (datemode == 0 and 1.0 <= xldate < 61.0)
+# @throws XLDateBadDatemode datemode arg is neither 0 nor 1
+# @throws XLDateBadTuple (year, month, day) is too early/late or has invalid component(s)
+# @throws XLDateError Covers the specific errors
+
+def xldate_from_date_tuple(datetuple, datemode):
+
+ (year, month, day) = datetuple
+ if datemode not in (0, 1):
+ raise XLDateBadDatemode(datemode)
+
+ if year == 0 and month == 0 and day == 0:
+ return 0.00
+
+ if not (1900 <= year <= 9999):
+ raise XLDateBadTuple("Invalid year: %r" % ((year, month, day),))
+ if not (1 <= month <= 12):
+ raise XLDateBadTuple("Invalid month: %r" % ((year, month, day),))
+ if day < 1 \
+ or (day > _days_in_month[month] and not(day == 29 and month == 2 and _leap(year))):
+ raise XLDateBadTuple("Invalid day: %r" % ((year, month, day),))
+
+ Yp = year + 4716
+ M = month
+ if M <= 2:
+ Yp = Yp - 1
+ Mp = M + 9
+ else:
+ Mp = M - 3
+ jdn = ifd(1461 * Yp, 4) + ifd(979 * Mp + 16, 32) + \
+ day - 1364 - ifd(ifd(Yp + 184, 100) * 3, 4)
+ xldays = jdn - _JDN_delta[datemode]
+ if xldays <= 0:
+ raise XLDateBadTuple("Invalid (year, month, day): %r" % ((year, month, day),))
+ if xldays < 61 and datemode == 0:
+ raise XLDateAmbiguous("Before 1900-03-01: %r" % ((year, month, day),))
+ return float(xldays)
+
+# Convert a time tuple (hour, minute, second) to an Excel "date" value (fraction of a day).
+# @param hour 0 <= hour < 24
+# @param minute 0 <= minute < 60
+# @param second 0 <= second < 60
+# @throws XLDateBadTuple Out-of-range hour, minute, or second
+
+def xldate_from_time_tuple(timetuple):
+ (hour, minute, second) = timetuple
+ if 0 <= hour < 24 and 0 <= minute < 60 and 0 <= second < 60:
+ return ((second / 60.0 + minute) / 60.0 + hour) / 24.0
+ raise XLDateBadTuple("Invalid (hour, minute, second): %r" % ((hour, minute, second),))
+
+# Convert a datetime tuple (year, month, day, hour, minute, second) to an Excel date value.
+# For more details, refer to other xldate_from_*_tuple functions.
+# @param datetime_tuple (year, month, day, hour, minute, second)
+# @param datemode 0: 1900-based, 1: 1904-based.
+
+def xldate_from_datetime_tuple(datetime_tuple, datemode):
+ return (
+ xldate_from_date_tuple(datetime_tuple[:3], datemode)
+ +
+ xldate_from_time_tuple(datetime_tuple[3:])
+ )
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