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# SPDX-License-Identifier: GPL-3.0-or-later
# Data structure for querying URL patterns.
#
# This file is part of Hydrilla&Haketilo.
#
# Copyright (C) 2021, 2022 Wojtek Kosior
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
#
#
# I, Wojtek Kosior, thereby promise not to sue for violation of this
# file's license. Although I request that you do not make use this code
# in a proprietary program, I am not going to enforce this in court.
"""
This module defines data structures for querying data using URL patterns.
"""
# Enable using with Python 3.7.
from __future__ import annotations
import typing as t
import dataclasses as dc
from immutables import Map
from .url_patterns import ParsedPattern, ParsedUrl, parse_url#, catchall_pattern
from .translations import smart_gettext as _
WrapperStoredType = t.TypeVar('WrapperStoredType', bound=t.Hashable)
@dc.dataclass(frozen=True, unsafe_hash=True, order=True)
class StoredTreeItem(t.Generic[WrapperStoredType]):
"""
In the Pattern Tree, each item is stored together with the pattern used to
register it.
"""
item: WrapperStoredType
pattern: ParsedPattern
NodeStoredType = t.TypeVar('NodeStoredType')
@dc.dataclass(frozen=True)
class PatternTreeNode(t.Generic[NodeStoredType]):
"""...."""
SelfType = t.TypeVar('SelfType', bound='PatternTreeNode[NodeStoredType]')
ChildrenType = Map[str, SelfType]
children: 'ChildrenType' = Map()
literal_match: t.Optional[NodeStoredType] = None
def is_empty(self) -> bool:
"""...."""
return len(self.children) == 0 and self.literal_match is None
def update_literal_match(
self: 'SelfType',
new_match_item: t.Optional[NodeStoredType]
) -> 'SelfType':
"""...."""
return dc.replace(self, literal_match=new_match_item)
def get_child(self: 'SelfType', child_key: str) -> t.Optional['SelfType']:
"""...."""
return self.children.get(child_key)
def remove_child(self: 'SelfType', child_key: str) -> 'SelfType':
"""...."""
try:
children = self.children.delete(child_key)
except:
children = self.children
return dc.replace(self, children=children)
def set_child(self: 'SelfType', child_key: str, child: 'SelfType') \
-> 'SelfType':
"""...."""
return dc.replace(self, children=self.children.set(child_key, child))
BranchStoredType = t.TypeVar('BranchStoredType')
BranchItemUpdater = t.Callable[
[t.Optional[BranchStoredType]],
t.Optional[BranchStoredType]
]
@dc.dataclass(frozen=True)
class PatternTreeBranch(t.Generic[BranchStoredType]):
"""...."""
SelfType = t.TypeVar(
'SelfType',
bound = 'PatternTreeBranch[BranchStoredType]'
)
root_node: PatternTreeNode[BranchStoredType] = PatternTreeNode()
def is_empty(self) -> bool:
"""...."""
return self.root_node.is_empty()
def update(
self: 'SelfType',
segments: t.Iterable[str],
item_updater: BranchItemUpdater
) -> 'SelfType':
"""
.......
"""
node = self.root_node
nodes_segments = []
for segment in segments:
next_node = node.get_child(segment)
nodes_segments.append((node, segment))
node = PatternTreeNode() if next_node is None else next_node
node = node.update_literal_match(item_updater(node.literal_match))
while nodes_segments:
prev_node, segment = nodes_segments.pop()
if node.is_empty():
node = prev_node.remove_child(segment)
else:
node = prev_node.set_child(segment, node)
return dc.replace(self, root_node=node)
def search(self, segments: t.Sequence[str]) -> t.Iterable[BranchStoredType]:
"""
Yields all matches of this segments sequence against the tree. Results
are produced in order from greatest to lowest pattern specificity.
"""
nodes = [self.root_node]
for segment in segments:
next_node = nodes[-1].get_child(segment)
if next_node is None:
break
nodes.append(next_node)
nsegments = len(segments)
cond_literal = lambda: len(nodes) == nsegments
cond_wildcard = [
lambda: len(nodes) + 1 == nsegments and segments[-1] != '*',
lambda: len(nodes) + 1 < nsegments,
lambda: len(nodes) + 1 != nsegments or segments[-1] != '***'
]
while nodes:
node = nodes.pop()
wildcard_matches = [node.get_child(wc) for wc in ('*', '**', '***')]
for match_node, condition in [
(node, cond_literal),
*zip(wildcard_matches, cond_wildcard)
]:
if match_node is not None:
if match_node.literal_match is not None:
if condition():
yield match_node.literal_match
FilterStoredType = t.TypeVar('FilterStoredType', bound=t.Hashable)
FilterWrappedType = StoredTreeItem[FilterStoredType]
def filter_by_trailing_slash(
items: t.Iterable[FilterWrappedType],
with_slash: bool
) -> frozenset[FilterWrappedType]:
"""...."""
return frozenset(wrapped for wrapped in items
if with_slash == wrapped.pattern.has_trailing_slash)
TreeStoredType = t.TypeVar('TreeStoredType', bound=t.Hashable)
StoredSet = frozenset[StoredTreeItem[TreeStoredType]]
PathBranch = PatternTreeBranch[StoredSet]
DomainBranch = PatternTreeBranch[PathBranch]
TreeRoot = Map[tuple[str, int], DomainBranch]
@dc.dataclass(frozen=True)
class PatternTree(t.Generic[TreeStoredType]):
"""
"Pattern Tree" is how we refer to the data structure used for querying
Haketilo patterns. Those look like 'https://*.example.com/ab/***'. The goal
is to make it possible to quickly retrieve all known patterns that match
a given URL.
"""
SelfType = t.TypeVar('SelfType', bound='PatternTree[TreeStoredType]')
_by_scheme_and_port: TreeRoot = Map()
def _register(
self: 'SelfType',
parsed_pattern: ParsedPattern,
item: TreeStoredType,
register: bool = True
) -> 'SelfType':
"""
Make an item wrapped in StoredTreeItem object queryable through the
Pattern Tree by the given parsed URL pattern.
"""
wrapped_item = StoredTreeItem(item, parsed_pattern)
def item_updater(item_set: t.Optional[StoredSet]) \
-> t.Optional[StoredSet]:
"""...."""
if item_set is None:
item_set = frozenset()
if register:
item_set = item_set.union((wrapped_item,))
else:
item_set = item_set.difference((wrapped_item,))
return None if len(item_set) == 0 else item_set
def path_branch_updater(path_branch: t.Optional[PathBranch]) \
-> t.Optional[PathBranch]:
"""...."""
if path_branch is None:
path_branch = PatternTreeBranch()
path_branch = path_branch.update(
parsed_pattern.path_segments,
item_updater
)
return None if path_branch.is_empty() else path_branch
key = (parsed_pattern.scheme, parsed_pattern.port)
domain_tree = self._by_scheme_and_port.get(key, PatternTreeBranch())
new_domain_tree = domain_tree.update(
parsed_pattern.domain_labels,
path_branch_updater
)
if new_domain_tree.is_empty():
try:
new_root = self._by_scheme_and_port.delete(key)
except KeyError:
new_root = self._by_scheme_and_port
else:
new_root = self._by_scheme_and_port.set(key, new_domain_tree)
return dc.replace(self, _by_scheme_and_port=new_root)
def register(
self: 'SelfType',
parsed_pattern: ParsedPattern,
item: TreeStoredType
) -> 'SelfType':
"""
Make item queryable through the Pattern Tree by the given URL pattern.
"""
return self._register(parsed_pattern, item)
def deregister(
self: 'SelfType',
parsed_pattern: ParsedPattern,
item: TreeStoredType
) -> 'SelfType':
"""
Make item no longer queryable through the Pattern Tree by the given URL
pattern.
"""
return self._register(parsed_pattern, item, register=False)
def search(self, url: t.Union[ParsedUrl, str]) -> t.Iterable[StoredSet]:
"""
....
"""
parsed_url = parse_url(url) if isinstance(url, str) else url
key = (parsed_url.scheme, parsed_url.port)
domain_tree = self._by_scheme_and_port.get(key)
if domain_tree is None:
return
if parsed_url.has_trailing_slash:
slash_options = [True, False]
else:
slash_options = [False]
for path_tree in domain_tree.search(parsed_url.domain_labels):
for item_set in path_tree.search(parsed_url.path_segments):
for with_slash in slash_options:
items = filter_by_trailing_slash(item_set, with_slash)
if len(items) > 0:
yield items
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