TimeRange Object

timerange.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

class TimeRange(object):
    """
    A basic structure to allow use to reason about non-contiguous dateranges in a single place
    """

    def __init__(self, start_dt=None, end_dt=None, ranges=None):
        self.start_dt = start_dt
        self.end_dt = end_dt
        if ranges is None:
            self.ranges = [self]
        else:
            self.ranges = ranges

    def format(self, dt):
        return dt.time()

    def add(self, new_range):
        if getattr(new_range, 'start_dt') is None or getattr(new_range, 'end_dt') is None:
            raise ValueError('Ranges must have a start and end dt')
        if new_range.start_dt > self.end_dt or new_range.end_dt < self.start_dt:
            # New range does not overlap with any existing ranges
            self.ranges.append(new_range)
            return
        if new_range.start_dt < self.start_dt:
            self.start_dt = new_range.start_dt
        if new_range.end_dt > self.end_dt:
            self.end_dt = new_range.end_dt
        if new_range.start_dt > self.start_dt and new_range.end_dt < self.end_dt:
            # if the new range is already within the existing range then ignore it. Then why is this
            # here? Just to make sure it's clear we didn't forget about that case
            pass

    def subtract(self, new_range):
        if new_range.start_dt > self.start_dt and new_range.end_dt < self.end_dt and len(self.ranges) == 1:
            # If range is later than start and earlier then finish, split this range into two
            # contiguous ranges
            self.ranges[0] = (self.start_dt, new_range.start_dt)
            self.ranges.append((new_range.start_dt, self.end_dt))
        if new_range.start_dt < self.start_dt and new_range.end_dt < self.end_dt:
            # if new range starts earlier and ends earlier than existing range then trucate range
            # fo start at new ranges end time
            self.start_dt = new_range.end_dt
        if self.start_dt < new_range.start_dt < self.end_dt < new_range.end_dt:
            self.start_dt = new_range.end_dt

    def __repr__(self):
        time_range_string = ''
        for r in self.ranges:
            time_range_string += '[{0} - {1}] '.format(self.format(r.start_dt), self.format(r.end_dt))
        return time_range_string