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import string
import re
import os
ALLOWED_KEYS = string.ascii_letters + string.digits + "`'"
class NonexistantBookmark(Exception):
pass
class Bookmarks(object):
"""Bookmarks is a container which associates keys with bookmarks.
A key is a string with: len(key) == 1 and key in ALLOWED_KEYS.
A bookmark is an object with: bookmark == bookmarktype(str(instance))
Which is true for str or FileSystemObject. This condition is required
so bookmark-objects can be saved to and loaded from a file.
Optionally, a bookmark.go() method is used for entering a bookmark.
"""
last_mtime = None
autosave = True
load_pattern = re.compile(r"^[\d\w`']:.")
def __init__(self, bookmarkfile, bookmarktype=str, autosave=False):
"""<bookmarkfile> specifies the path to the file where
bookmarks are saved in.
"""
self.autosave = autosave
self.dct = {}
self.path = bookmarkfile
self.bookmarktype = bookmarktype
def load(self):
"""Load the bookmarks from path/bookmarks"""
try:
new_dict = self._load_dict()
except OSError:
return
self._set_dict(new_dict)
def delete(self, key):
"""Delete the bookmark with the given key"""
if key in self.dct:
del self.dct[key]
if self.autosave: self.save()
def enter(self, key):
"""Enter the bookmark with the given key.
Requires the bookmark instance to have a go() method.
"""
try:
return self[key].go()
except (IndexError, KeyError, AttributeError):
return False
def update_if_outdated(self):
if self.last_mtime != self._get_mtime():
self.update()
def remember(self, value):
"""Bookmarks <value> to the keys ` and '"""
self["`"] = value
self["'"] = value
if self.autosave: self.save()
def __iter__(self):
return iter(self.dct.items())
def __getitem__(self, key):
"""Get the bookmark associated with the key"""
if key in self.dct:
return self.dct[key]
else:
raise NonexistantBookmark()
def __setitem__(self, key, value):
"""Bookmark <value> to the key <key>.
key is expected to be a 1-character string and element of ALLOWED_KEYS.
value is expected to be a filesystemobject.
"""
if key in ALLOWED_KEYS:
self.dct[key] = value
if self.autosave: self.save()
def __contains__(self, key):
"""Test whether a bookmark-key is defined"""
return key in self.dct
def update(self):
"""Update the bookmarks from the bookmark file.
Useful if two instances are running which define different bookmarks.
"""
try:
real_dict = self._load_dict()
except OSError:
return
for key in set(self.dct.keys()) | set(real_dict.keys()):
if key in self.dct:
current = self.dct[key]
else:
current = None
if key in self.original_dict:
original = self.original_dict[key]
else:
original = None
if key in real_dict:
real = real_dict[key]
else:
real = None
if current == original and current != real:
continue
if key not in self.dct:
del real_dict[key]
else:
real_dict[key] = current
self._set_dict(real_dict)
def save(self):
"""Save the bookmarks to the bookmarkfile.
This is done automatically after every modification if autosave is True."""
import os
self.update()
if os.access(self.path, os.W_OK):
f = open(self.path, 'w')
for key, value in self.dct.items():
if type(key) == str\
and key in ALLOWED_KEYS:
f.write("{0}:{1}\n".format(str(key), str(value)))
f.close()
self._update_mtime()
def _load_dict(self):
import os
dct = {}
if os.access(self.path, os.R_OK):
f = open(self.path, 'r')
for line in f:
if self.load_pattern.match(line):
key, value = line[0], line[2:-1]
if key in ALLOWED_KEYS:
dct[key] = self.bookmarktype(value)
f.close()
return dct
else:
raise OSError('Cannot read the given path')
def _set_dict(self, dct):
self.dct.clear()
self.dct.update(dct)
self.original_dict = self.dct.copy()
self._update_mtime()
def _get_mtime(self):
import os
try:
return os.stat(self.path).st_mtime
except OSError:
return None
def _update_mtime(self):
self.last_mtime = self._get_mtime()
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