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1# This file is part of daf_butler. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (http://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <http://www.gnu.org/licenses/>. 

21from __future__ import annotations 

22 

23__all__ = ("Timespan", "TIMESPAN_FIELD_SPECS") 

24 

25import operator 

26from typing import Generic, Optional, TypeVar 

27 

28from sqlalchemy import DateTime 

29 

30from . import ddl 

31 

32 

33T = TypeVar("T") 

34 

35 

36class Timespan(Generic[T], tuple): 

37 

38 def __new__(cls, begin: T, end: T): 

39 return tuple.__new__(cls, (begin, end)) 

40 

41 def overlaps(self, other, ops=operator): 

42 return ops.not_(ops.or_(self.end < other.begin, self.begin > other.end)) 

43 

44 def intersection(*args) -> Optional[Timespan]: 

45 if len(args) == 0: 

46 return None 

47 elif len(args) == 1: 

48 return args[0] 

49 else: 

50 begin = max(*[ts.begin for ts in args]) 

51 end = min(*[ts.end for ts in args]) 

52 if begin > end: 

53 return None 

54 return Timespan(begin=begin, end=end) 

55 

56 @property 

57 def begin(self) -> T: 

58 return self[0] 

59 

60 @property 

61 def end(self) -> T: 

62 return self[1] 

63 

64 def __getnewargs__(self) -> tuple: 

65 return (self.begin, self.end) 

66 

67 

68TIMESPAN_FIELD_SPECS = Timespan( 

69 begin=ddl.FieldSpec(name="datetime_begin", dtype=DateTime), 

70 end=ddl.FieldSpec(name="datetime_end", dtype=DateTime), 

71)