Regex to get multiple dates out of given kind of strings

I got you started. This is my interpretation of your problem. I leave the implementation of parse_complex up to you.

class DateParser(object): """parse dates according to the custom rules here: >>> DateParser("Sat 1 Dec - 11h + 14h / Sun 2 Dec - 12h30").parse() ("Sat 1 Dec 11h", "Sat 1 Dec 14h", "Sun 2 Dec 12h30") >>> DateParser("Tue 27 + Wed 28 Nov - 20h30").parse() ("Tue 27 Nov 20h30", "Wed 28 Nov 20h30") >>> DateParser("Fri 4 + Sat 5 Jan - 20h30").parse() ("Fri 4 Jan 20h30", "Sat 5 Jan 20h30") >>> DateParser("Wed 23 Jan - 20h").parse() ("Wed 23 Jan 20h") >>> DateParser("Sat 26 Jan - 11h + 14h / Sun 27 Jan - 11h").parse() ("Sat 26 Jan 11h", "Sat 26 Jan 14h", "Sun 27 Jan 11h") >>> DateParser("Fri 8 and Sat 9 Feb - 20h30 + thu 1 feb - 15h").parse() ("Fri 8 Feb 20h30", "Sat 9 Feb 20h30", "Thu 1 feb 15h") >>> DateParse("Sat 2 Mar - 11h + 14h / Sun 3 Mar - 11h").parse() ("Sat 2 Mar 11h", "Sat 2 Mar 14h", "Sun 3 Mar 11h") >>> DateParser("Wed 12, Thu 13, Fri 14 and Sat 15 Jun - 19h + Sun 16 Jun - 12h30").parse() ("Wed 12 Jun 19h", "Thu 13 Jun 19h", "Fri 14 Jun 19h", "Sat 15 Jun 19h", "Sun 16 Jun 12h30") """ def __init__(self, line): self.date = line self.dates = self.split_dates(line) self.final = [] self.days = ['mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun'] self.mons = ['jan', 'feb', 'mar', 'apr', 'may', 'jun', 'jul', 'aug', 'sep', 'oct', 'nov', 'dec'] def parse(self): if self.is_complex(): self.parse_complex() else: self.parse_simple() return tuple(self.final) def parse_simple(self): """typical formats: Day 00 + Day 01 Mon - 00h00 Day 00 Mon - 00h00 + 01h00 Day 00 Mon - 00h00 / Day 02 Mon - 00h00 """ for date in self.dates: mods = self.split_modifiers(date) date_mods = [] for mod in mods: if self.is_complete(mod): #only *one* base_date base_date, time = self.split_time(mod) date_mods.append(time) else: date_mods.append(mod) for mod in date_mods: if self.is_hour(mod): #Sat 1 Dec - 11h + 14h self.final.append(' '.join([base_date, mod])) else: #Fri 4 + Sat 5 Jan - 20h30 self.final.append(' '.join([mod, self.extract_month(base_date), time])) def parse_complex(self): """typical format: Day 00, Day 01 and Day 02 Mon - 00h00 + Day 03 Mon 01h00 """ raise NotImplementedError() def is_complex(self): """presence of the complex date attribute requires special parsing""" return self.date.find(' and ') > -1 def is_complete(self, section): """section has format `Day 00 Mon - 00h00` must have no modifiers to determine completeness """ sections = map(lambda x: x.lower(), section.split()) try: dow, dom, moy, dash, time = sections except ValueError, e: return False return all([dow in self.days, moy in self.mons]) def is_hour(self, section): return section[0].isdigit() def is_day(self, section): return section[:3].lower() in self.days def extract_month(self, section): """return the month present in the string, if any""" for mon in self.mons: if section.lower().find(mon) > -1: found = section.lower().index(mon) return section[found : found + 3] return None def split_dates(self, section): """split individual dates from a list of dates""" return section.split(' / ') def split_time(self, section): """split individual times from a complete date""" return section.split(' - ') def split_modifiers(self, section): """extend a date by implying that they share a date or a time modifiers change their meaning when parsing a complex date """ return section.split(' + ') >>> DateParser("Fri 4 + Sat 5 Jan - 20h30 / Sat 1 Dec - 11h + 14h + 16h / Sun 2 Dec - 12h30").parse() ('Fri 4 Jan 20h30', 'Sat 5 Jan 20h30', 'Sat 1 Dec 11h', 'Sat 1 Dec 14h', 'Sat 1 Dec 16h', 'Sun 2 Dec 12h30') 

If you have questions about the way I've documented this class, feel free to get back to me, and I can help you out some more. This problem was a little more complex than I first thought, I need to get some other stuff done first.