days.py

#!/usr/bin/env python3

import codecs
import datetime

class Day:
    def __init__(self, name, date):
        self.name = name
        self.date = date
    
    def __str__(self):
        return u'%s %s' % (self.name, formatdate(self.date))
    
    def __cmp__(self, other):
        if isinstance(other, Day):
            return cmp(self.date, other.date)
        else:
            return cmp(self.date, other)
    
    def _is_leap_year(self, year):
        if year % 400 == 0:
            return True
        elif year % 100 == 0:
            return False
        elif year % 4 == 0:
            return True
        else:
            return False
    
    def _next_leap_year(self, year):
        if _is_leap_year((year//4+1)*4):
            return (year//4+1)*4
        else:
            return (year//4+2)*4
    
    def next_anniversary(self, date=None):
        if date == None:
            date = datetime.date.today()
        
        if not (self.date.month == 2 and self.date.day == 29):
            if date > datetime.date(date.year, self.date.month, self.date.day):
                return datetime.date(date.year + 1, self.date.month, self.date.day)
            else:
                return datetime.date(date.year, self.date.month, self.date.day)
        else:
            if self._is_leap_year(date.year) and ((date.month, date.day) <= (2, 29)):   
                return datetime.date(date.year, 2, 29)
            else:
                return datetime.date(self._next_leap_year(date.year), 2, 29)
    
    def is_semicentennial(self, year=None):
        if year == None:
            year = datetime.date.today().year
        
        return (year - self.date.year) % 50 == 0

def parsedate(s):
    return datetime.datetime.strptime(s, '%Y-%m-%d').date()

def formatdate(d):
    return d.isoformat()

def load(filename):
    with codecs.open('days.tsv', encoding='utf-8') as f:
        days = sorted([Day(l.split('\t')[0], parsedate(l.split('\t')[1].strip())) for l in f.readlines()], key=lambda d: d.date)
    return days

days.tsv