Hide keyboard shortcuts

Hot-keys on this page

r m x p   toggle line displays

j k   next/prev highlighted chunk

0   (zero) top of page

1   (one) first highlighted chunk

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

# This file is part of daf_butler. 

# 

# Developed for the LSST Data Management System. 

# This product includes software developed by the LSST Project 

# (http://www.lsst.org). 

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

# for details of code ownership. 

# 

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

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

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

# (at your option) any later version. 

# 

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

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

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

# GNU General Public License for more details. 

# 

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

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

 

__all__ = ("Location", "LocationFactory") 

 

import os 

import os.path 

import urllib 

 

 

class Location: 

"""Identifies a location in the `Datastore`. 

""" 

 

__slots__ = ("_datastoreRoot", "_uri") 

 

def __init__(self, datastoreRoot, uri): 

self._datastoreRoot = datastoreRoot 

self._uri = urllib.parse.urlparse(uri) 

 

def __str__(self): 

return self.uri 

 

@property 

def uri(self): 

"""URI corresponding to location. 

""" 

return self._uri.geturl() 

 

@property 

def path(self): 

"""Path corresponding to location. 

 

This path includes the root of the `Datastore`. 

""" 

return os.path.join(self._datastoreRoot, self._uri.path.lstrip("/")) 

 

@property 

def pathInStore(self): 

"""Path corresponding to location relative to `Datastore` root. 

""" 

return self._uri.path.lstrip("/") 

 

def updateExtension(self, ext): 

"""Update the file extension associated with this `Location`. 

 

Parameters 

---------- 

ext : `str` 

New extension. If an empty string is given any extension will 

be removed. If `None` is given there will be no change. 

""" 

if ext is None: 

return 

path, _ = os.path.splitext(self._uri.path) 

 

# Ensure that we have a leading "." on file extension (and we do not 

# try to modify the empty string) 

if ext and not ext.startswith("."): 

ext = "." + ext 

 

parts = list(self._uri) 

parts[2] = path + ext 

self._uri = urllib.parse.urlparse(urllib.parse.urlunparse(parts)) 

 

 

class LocationFactory: 

"""Factory for `Location` instances. 

""" 

 

def __init__(self, datastoreRoot): 

"""Constructor 

 

Parameters 

---------- 

datastoreRoot : `str` 

Root location of the `Datastore` in the filesystem. 

""" 

self._datastoreRoot = datastoreRoot 

 

def fromUri(self, uri): 

"""Factory function to create a `Location` from a URI. 

 

Parameters 

---------- 

uri : `str` 

A valid Universal Resource Identifier. 

 

Returns 

location : `Location` 

The equivalent `Location`. 

""" 

if uri is None or not isinstance(uri, str): 

raise ValueError("URI must be a string and not {}".format(uri)) 

return Location(self._datastoreRoot, uri) 

 

def fromPath(self, path): 

"""Factory function to create a `Location` from a POSIX path. 

 

Parameters 

---------- 

path : `str` 

A standard POSIX path, relative to the `Datastore` root. 

 

Returns 

location : `Location` 

The equivalent `Location`. 

""" 

uri = urllib.parse.urljoin("file://", path) 

return self.fromUri(uri)