git.maemo.org Git - theonering/blob - src/util/io.py

   1 #!/usr/bin/env python
   2
   3
   4 from __future__ import with_statement
   5
   6 import os
   7 import pickle
   8 import contextlib
   9 import itertools
  10 import functools
  11
  12
  13 @contextlib.contextmanager
  14 def change_directory(directory):
  15         previousDirectory = os.getcwd()
  16         os.chdir(directory)
  17         currentDirectory = os.getcwd()
  18
  19         try:
  20                 yield previousDirectory, currentDirectory
  21         finally:
  22                 os.chdir(previousDirectory)
  23
  24
  25 @contextlib.contextmanager
  26 def pickled(filename):
  27         """
  28         Here is an example usage:
  29         with pickled("foo.db") as p:
  30                 p("users", list).append(["srid", "passwd", 23])
  31         """
  32
  33         if os.path.isfile(filename):
  34                 data = pickle.load(open(filename))
  35         else:
  36                 data = {}
  37
  38         def getter(item, factory):
  39                 if item in data:
  40                         return data[item]
  41                 else:
  42                         data[item] = factory()
  43                         return data[item]
  44
  45         yield getter
  46
  47         pickle.dump(data, open(filename, "w"))
  48
  49
  50 @contextlib.contextmanager
  51 def redirect(object_, attr, value):
  52         """
  53         >>> import sys
  54         ... with redirect(sys, 'stdout', open('stdout', 'w')):
  55         ...     print "hello"
  56         ...
  57         >>> print "we're back"
  58         we're back
  59         """
  60         orig = getattr(object_, attr)
  61         setattr(object_, attr, value)
  62         try:
  63                 yield
  64         finally:
  65                 setattr(object_, attr, orig)
  66
  67
  68 def pathsplit(path):
  69         """
  70         >>> pathsplit("/a/b/c")
  71         ['', 'a', 'b', 'c']
  72         >>> pathsplit("./plugins/builtins.ini")
  73         ['.', 'plugins', 'builtins.ini']
  74         """
  75         pathParts = path.split(os.path.sep)
  76         return pathParts
  77
  78
  79 def commonpath(l1, l2, common=None):
  80         """
  81         >>> commonpath(pathsplit('/a/b/c/d'), pathsplit('/a/b/c1/d1'))
  82         (['', 'a', 'b'], ['c', 'd'], ['c1', 'd1'])
  83         >>> commonpath(pathsplit("./plugins/"), pathsplit("./plugins/builtins.ini"))
  84         (['.', 'plugins'], [''], ['builtins.ini'])
  85         >>> commonpath(pathsplit("./plugins/builtins"), pathsplit("./plugins"))
  86         (['.', 'plugins'], ['builtins'], [])
  87         """
  88         if common is None:
  89                 common = []
  90
  91         if l1 == l2:
  92                 return l1, [], []
  93
  94         for i, (leftDir, rightDir) in enumerate(zip(l1, l2)):
  95                 if leftDir != rightDir:
  96                         return l1[0:i], l1[i:], l2[i:]
  97         else:
  98                 if leftDir == rightDir:
  99                         i += 1
 100                 return l1[0:i], l1[i:], l2[i:]
 101
 102
 103 def relpath(p1, p2):
 104         """
 105         >>> relpath('/', '/')
 106         './'
 107         >>> relpath('/a/b/c/d', '/')
 108         '../../../../'
 109         >>> relpath('/a/b/c/d', '/a/b/c1/d1')
 110         '../../c1/d1'
 111         >>> relpath('/a/b/c/d', '/a/b/c1/d1/')
 112         '../../c1/d1'
 113         >>> relpath("./plugins/builtins", "./plugins")
 114         '../'
 115         >>> relpath("./plugins/", "./plugins/builtins.ini")
 116         'builtins.ini'
 117         """
 118         sourcePath = os.path.normpath(p1)
 119         destPath = os.path.normpath(p2)
 120
 121         (common, sourceOnly, destOnly) = commonpath(pathsplit(sourcePath), pathsplit(destPath))
 122         if len(sourceOnly) or len(destOnly):
 123                 relParts = itertools.chain(
 124                         (('..' + os.sep) * len(sourceOnly), ),
 125                         destOnly,
 126                 )
 127                 return os.path.join(*relParts)
 128         else:
 129                 return "."+os.sep