DAL5 continues to refine the file system's interface and provides methods that should look similar to what most programmers are used to working with. Files have still not been completely abstracted away and all path names must be given as relative to the root. The path separator is defined in this module along with a list of characters for valid file and directory names.
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################################################################################
class DAL5:
# DEFAULTS
PATH_SEPARATOR = ' '
NAME_CHARACTERS = ''.join([chr(i) for i in range(256) \
if len(repr(chr(i))) == 3])
# Disk Abstraction Layer
def __init__(self, blocks, size):
self.__disk = DAL4(blocks, size)
# Make New Directory
def make_directory(self, path):
block, name = self.__resolve_path(path)
self.__disk.make_directory(block, name)
# Remove Old Directory
def remove_directory(self, path):
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
assert block
assert self.__disk.is_directory(block)
assert self.__disk.empty(block)
self.__disk.remove_directory(block)
# Make New File
def make_file(self, path):
block, name = self.__resolve_path(path)
self.__disk.make_file(block, name)
# Remove Old File
def remove_file(self, path):
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
assert block
assert self.__disk.is_file(block)
self.__disk.remove_file(block)
# Read From File
def read_file(self, path):
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
assert block
return self.__disk.read_file(block)
# Write To File
def write_file(self, path, data):
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
assert block
self.__disk.write_file(block, data)
# Get Directory Contents
def list_directory(self, path):
if path:
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
assert block
else:
block = 1
directory = self.__disk.list_directory(block)
names = [self.__disk.name(block) for block in directory]
return names
# Check If Empty
def empty(self, path):
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
assert block
return self.__disk.empty(block)
# Changes Directory/File Name
def rename(self, path, name):
block, old_name = self.__resolve_path(path)
block = self.__disk.find(block, old_name)
assert block
self.__disk.rename(block, name)
# Test For Existance
def exists(self, path):
try:
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
assert block
return True
except:
return False
# Check If File
def is_file(self, path):
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
return self.__disk.is_file(block)
# Check If Directory
def is_directory(self, path):
assert type(path) is str
if path:
block, name = self.__resolve_path(path)
block = self.__disk.find(block, name)
return self.__disk.is_directory(block)
else:
return True
# Seed Control Interface
def seed(self, data=None):
return self.__disk.seed(data)
# Probability Of Failure
def fail(self, probability):
self.__disk.fail(probability)
# Dump To File
def dump(self, name):
self.__disk.dump(name)
# Load From File
def load(self, name, abstract):
assert type(abstract) is bool
self.__disk.load(name, abstract)
if abstract:
self.__soft()
else:
self.__hard()
# Fix All Errors
def __soft(self):
# Not Yet Implemented
pass
# Find Any Error
def __hard(self):
# Not Yet Implemented
pass
# Private Utility Function
def __resolve_path(self, path):
assert type(path) is str
if path:
table = ''.join([chr(i) for i in range(256)])
parts = path.split(self.PATH_SEPARATOR)
block = 1
for name in parts[:-1]:
assert len(name.translate(table, self.NAME_CHARACTERS)) == 0
block = self.__disk.find(block, name)
assert block
assert parts[-1]
assert len(parts[-1].translate(table, self.NAME_CHARACTERS)) == 0
return block, parts[-1]
else:
return 1, ''
################################################################################
def test():
# Not Yet Implemented
pass
################################################################################
if __name__ == '__main__':
test()
|
This recipe is part of a group of recipes that detail the creation of an abstract file system. dal_4.py can be found at http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/492212
Tags: files
