cpython/Lib/calendar.py

214 lines
6.1 KiB
Python

# module calendar
##############################
# Calendar support functions #
##############################
# This is based on UNIX ctime() et al. (also Standard C and POSIX)
# Subtle but crucial differences:
# - the order of the elements of a 'struct tm' differs, to ease sorting
# - months numbers are 1-12, not 0-11; month arrays have a dummy element 0
# - Monday is the first day of the week (numbered 0)
# These are really parameters of the 'time' module:
epoch = 1970 # Time began on January 1 of this year (00:00:00 UCT)
day_0 = 3 # The epoch begins on a Thursday (Monday = 0)
# Return 1 for leap years, 0 for non-leap years
def isleap(year):
return year % 4 == 0 and (year % 100 <> 0 or year % 400 == 0)
# Constants for months referenced later
January = 1
February = 2
# Number of days per month (except for February in leap years)
mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
# Exception raised for bad input (with string parameter for details)
error = 'calendar error'
# Turn seconds since epoch into calendar time
def gmtime(secs):
if secs < 0: raise error, 'negative input to gmtime()'
mins, secs = divmod(secs, 60)
hours, mins = divmod(mins, 60)
days, hours = divmod(hours, 24)
wday = (days + day_0) % 7
year = epoch
# XXX Most of the following loop can be replaced by one division
while 1:
yd = 365 + isleap(year)
if days < yd: break
days = days - yd
year = year + 1
yday = days
month = January
while 1:
md = mdays[month] + (month == February and isleap(year))
if days < md: break
days = days - md
month = month + 1
return year, month, days + 1, hours, mins, secs, yday, wday
# XXX Week number also?
# Return number of leap years in range [y1, y2)
# Assume y1 <= y2 and no funny (non-leap century) years
def leapdays(y1, y2):
return (y2+3)/4 - (y1+3)/4
# Inverse of gmtime():
# Turn UCT calendar time (less yday, wday) into seconds since epoch
def mktime(year, month, day, hours, mins, secs):
days = day - 1
for m in range(January, month): days = days + mdays[m]
if isleap(year) and month > February: days = days+1
days = days + (year-epoch)*365 + leapdays(epoch, year)
return ((days*24 + hours)*60 + mins)*60 + secs
# Full and abbreviated names of weekdays
day_name = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', \
'Friday', 'Saturday', 'Sunday']
day_abbr = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
# Full and abbreviated of months (1-based arrays!!!)
month_name = ['', 'January', 'February', 'March', 'April', \
'May', 'June', 'July', 'August', \
'September', 'October', 'November', 'December']
month_abbr = [' ', 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', \
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
# Zero-fill string to two positions (helper for asctime())
def dd(s):
while len(s) < 2: s = '0' + s
return s
# Blank-fill string to two positions (helper for asctime())
def zd(s):
while len(s) < 2: s = ' ' + s
return s
# Turn calendar time as returned by gmtime() into a string
# (the yday parameter is for compatibility with gmtime())
def asctime(year, month, day, hours, mins, secs, yday, wday):
s = day_abbr[wday] + ' ' + month_abbr[month] + ' ' + zd(`day`)
s = s + ' ' + dd(`hours`) + ':' + dd(`mins`) + ':' + dd(`secs`)
return s + ' ' + `year`
# Localization: Minutes West from Greenwich
# timezone = -2*60 # Middle-European time with DST on
timezone = 5*60 # EST (sigh -- THINK time() doesn't return UCT)
# Local time ignores DST issues for now -- adjust 'timezone' to fake it
def localtime(secs):
return gmtime(secs - timezone*60)
# UNIX-style ctime (except it doesn't append '\n'!)
def ctime(secs):
return asctime(localtime(secs))
######################
# Non-UNIX additions #
######################
# Calendar printing etc.
# Return weekday (0-6 ~ Mon-Sun) for year (1970-...), month (1-12), day (1-31)
def weekday(year, month, day):
secs = mktime(year, month, day, 0, 0, 0)
days = secs / (24*60*60)
return (days + day_0) % 7
# Return weekday (0-6 ~ Mon-Sun) and number of days (28-31) for year, month
def monthrange(year, month):
day1 = weekday(year, month, 1)
ndays = mdays[month] + (month == February and isleap(year))
return day1, ndays
# Return a matrix representing a month's calendar
# Each row represents a week; days outside this month are zero
def _monthcalendar(year, month):
day1, ndays = monthrange(year, month)
rows = []
r7 = range(7)
day = 1 - day1
while day <= ndays:
row = [0, 0, 0, 0, 0, 0, 0]
for i in r7:
if 1 <= day <= ndays: row[i] = day
day = day + 1
rows.append(row)
return rows
# Caching interface to _monthcalendar
mc_cache = {}
def monthcalendar(year, month):
key = `year` + month_abbr[month]
try:
return mc_cache[key]
except IOError:
mc_cache[key] = ret = _monthcalendar(year, month)
return ret
# Center a string in a field
def center(str, width):
n = width - len(str)
if n < 0: return str
return ' '*(n/2) + str + ' '*(n-n/2)
# XXX The following code knows that print separates items with space!
# Print a single week (no newline)
def prweek(week, width):
for day in week:
if day == 0: print ' '*width,
else:
if width > 2: print ' '*(width-3),
if day < 10: print '',
print day,
# Return a header for a week
def weekheader(width):
str = ''
for i in range(7):
if str: str = str + ' '
str = str + day_abbr[i%7][:width]
return str
# Print a month's calendar
def prmonth(year, month):
print weekheader(3)
for week in monthcalendar(year, month):
prweek(week, 3)
print
# Spacing between month columns
spacing = ' '
# 3-column formatting for year calendars
def format3c(a, b, c):
print center(a, 20), spacing, center(b, 20), spacing, center(c, 20)
# Print a year's calendar
def prcal(year):
header = weekheader(2)
format3c('', `year`, '')
for q in range(January, January+12, 3):
print
format3c(month_name[q], month_name[q+1], month_name[q+2])
format3c(header, header, header)
data = []
height = 0
for month in range(q, q+3):
cal = monthcalendar(year, month)
if len(cal) > height: height = len(cal)
data.append(cal)
for i in range(height):
for cal in data:
if i >= len(cal):
print ' '*20,
else:
prweek(cal[i], 2)
print spacing,
print