pferd/PFERD/report.py
2021-05-15 22:25:48 +02:00

101 lines
2.6 KiB
Python

from dataclasses import dataclass
from pathlib import PurePath
from typing import Set
@dataclass
class MarkDuplicateException(Exception):
"""
Tried to mark a file that was already marked.
"""
path: PurePath
@dataclass
class MarkConflictException(Exception):
"""
Marking the path would have caused a conflict.
A conflict can have two reasons: Either the new file has the same path as
the parent directory of a known file, or a parent directory of the new file
has the same path as a known file. In either case, adding the new file
would require a file and a directory to share the same path, which is
usually not possible.
"""
path: PurePath
collides_with: PurePath
# TODO Use PurePath.is_relative_to when updating to 3.9
def is_relative_to(a: PurePath, b: PurePath) -> bool:
try:
a.relative_to(b)
return True
except ValueError:
return False
class Report:
"""
A report of a synchronization. Includes all files found by the crawler, as
well as the set of changes made to local files.
"""
def __init__(self) -> None:
self.reserved_files: Set[PurePath] = set()
self.known_files: Set[PurePath] = set()
self.new_files: Set[PurePath] = set()
self.changed_files: Set[PurePath] = set()
self.deleted_files: Set[PurePath] = set()
def mark_reserved(self, path: PurePath) -> None:
self.reserved_files.add(path)
def mark(self, path: PurePath) -> None:
"""
Mark a previously unknown file as known.
May throw a MarkDuplicateException or a MarkConflictException. For more
detail, see the respective exception's docstring.
"""
for other in self.marked:
if path == other:
raise MarkDuplicateException(path)
if is_relative_to(path, other) or is_relative_to(other, path):
raise MarkConflictException(path, other)
self.known_files.add(path)
@property
def marked(self) -> Set[PurePath]:
return self.known_files | self.reserved_files
def is_marked(self, path: PurePath) -> bool:
return path in self.marked
def add_file(self, path: PurePath) -> None:
"""
Unlike mark(), this function accepts any paths.
"""
self.new_files.add(path)
def change_file(self, path: PurePath) -> None:
"""
Unlike mark(), this function accepts any paths.
"""
self.changed_files.add(path)
def delete_file(self, path: PurePath) -> None:
"""
Unlike mark(), this function accepts any paths.
"""
self.deleted_files.add(path)