Adding utils

[gonvert] / src / util / io.py

diff --git a/src/util/io.py b/src/util/io.py
new file mode 100644 (file)
index 0000000..aece2dd
--- /dev/null
+++ b/src/util/io.py
@@ -0,0 +1,129 @@
+#!/usr/bin/env python
+
+
+from __future__ import with_statement
+
+import os
+import pickle
+import contextlib
+import itertools
+import functools
+
+
+@contextlib.contextmanager
+def change_directory(directory):
+       previousDirectory = os.getcwd()
+       os.chdir(directory)
+       currentDirectory = os.getcwd()
+
+       try:
+               yield previousDirectory, currentDirectory
+       finally:
+               os.chdir(previousDirectory)
+
+
+@contextlib.contextmanager
+def pickled(filename):
+       """
+       Here is an example usage:
+       with pickled("foo.db") as p:
+               p("users", list).append(["srid", "passwd", 23])
+       """
+
+       if os.path.isfile(filename):
+               data = pickle.load(open(filename))
+       else:
+               data = {}
+
+       def getter(item, factory):
+               if item in data:
+                       return data[item]
+               else:
+                       data[item] = factory()
+                       return data[item]
+
+       yield getter
+
+       pickle.dump(data, open(filename, "w"))
+
+
+@contextlib.contextmanager
+def redirect(object_, attr, value):
+       """
+       >>> import sys
+       ... with redirect(sys, 'stdout', open('stdout', 'w')):
+       ...     print "hello"
+       ...
+       >>> print "we're back"
+       we're back
+       """
+       orig = getattr(object_, attr)
+       setattr(object_, attr, value)
+       try:
+               yield
+       finally:
+               setattr(object_, attr, orig)
+
+
+def pathsplit(path):
+       """
+       >>> pathsplit("/a/b/c")
+       ['', 'a', 'b', 'c']
+       >>> pathsplit("./plugins/builtins.ini")
+       ['.', 'plugins', 'builtins.ini']
+       """
+       pathParts = path.split(os.path.sep)
+       return pathParts
+
+
+def commonpath(l1, l2, common=None):
+       """
+       >>> commonpath(pathsplit('/a/b/c/d'), pathsplit('/a/b/c1/d1'))
+       (['', 'a', 'b'], ['c', 'd'], ['c1', 'd1'])
+       >>> commonpath(pathsplit("./plugins/"), pathsplit("./plugins/builtins.ini"))
+       (['.', 'plugins'], [''], ['builtins.ini'])
+       >>> commonpath(pathsplit("./plugins/builtins"), pathsplit("./plugins"))
+       (['.', 'plugins'], ['builtins'], [])
+       """
+       if common is None:
+               common = []
+
+       if l1 == l2:
+               return l1, [], []
+
+       for i, (leftDir, rightDir) in enumerate(zip(l1, l2)):
+               if leftDir != rightDir:
+                       return l1[0:i], l1[i:], l2[i:]
+       else:
+               if leftDir == rightDir:
+                       i += 1
+               return l1[0:i], l1[i:], l2[i:]
+
+
+def relpath(p1, p2):
+       """
+       >>> relpath('/', '/')
+       './'
+       >>> relpath('/a/b/c/d', '/')
+       '../../../../'
+       >>> relpath('/a/b/c/d', '/a/b/c1/d1')
+       '../../c1/d1'
+       >>> relpath('/a/b/c/d', '/a/b/c1/d1/')
+       '../../c1/d1'
+       >>> relpath("./plugins/builtins", "./plugins")
+       '../'
+       >>> relpath("./plugins/", "./plugins/builtins.ini")
+       'builtins.ini'
+       """
+       sourcePath = os.path.normpath(p1)
+       destPath = os.path.normpath(p2)
+
+       (common, sourceOnly, destOnly) = commonpath(pathsplit(sourcePath), pathsplit(destPath))
+       if len(sourceOnly) or len(destOnly):
+               relParts = itertools.chain(
+                       (('..' + os.sep) * len(sourceOnly), ),
+                       destOnly,
+               )
+               return os.path.join(*relParts)
+       else:
+               return "."+os.sep