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"""
Matches are specific elements found on a page that match a sample.
"""
import logging
import typing
from functools import cached_property
from itertools import combinations
from itertools import product
from mlscraper.html import get_relative_depth
from mlscraper.html import get_root_node
from mlscraper.html import get_similarity
from mlscraper.html import HTMLAttributeMatch
from mlscraper.html import HTMLExactTextMatch
from mlscraper.html import Node
class Match:
"""
Occurrence of a specific sample on a page
"""
@property
def root(self) -> Node:
"""
The lowest element that contains matched elements.
"""
raise NotImplementedError()
def has_overlap(self, other_match: "Match"):
assert isinstance(other_match, Match)
return (
# overlap if same root node
self.root == other_match.root
# or if one is a parent of the other one
or self.root.has_ancestor(other_match.root)
or other_match.root.has_ancestor(self.root)
)
@property
def depth(self):
"""
How deep inside the DOM the match is.
"""
# depth of root compared to document
return self.root.depth
@property
def span(self):
"""
Heuristic for how big of a subtree the match spans.
"""
raise NotImplementedError()
def get_similarity_to(self, match: "Match"):
raise NotImplementedError()
class Extractor:
"""
Class that extracts values from a node.
"""
def extract(self, node: Node):
raise NotImplementedError()
class TextValueExtractor(Extractor):
"""
Class to extract text from a node.
"""
def extract(self, node: Node):
return node.soup.text.strip()
def __repr__(self):
return f"<{self.__class__.__name__}>"
def __hash__(self):
# todo each instance equals each other instance,
# so this holds,
# but it isn't pretty
return 0
def __eq__(self, other):
return isinstance(other, TextValueExtractor)
class AttributeValueExtractor(Extractor):
"""
Extracts a value from the attribute in an html tag.
"""
attr = None
def __init__(self, attr):
self.attr = attr
def extract(self, node: Node):
if self.attr in node.soup.attrs:
return node.soup[self.attr]
def __repr__(self):
return f"<{self.__class__.__name__} {self.attr=}>"
def __hash__(self):
return self.attr.__hash__()
def __eq__(self, other):
return isinstance(other, AttributeValueExtractor) and self.attr == other.attr
class DictMatch(Match):
match_by_key = None
def __init__(self, match_by_key: dict):
self.match_by_key = match_by_key
@cached_property
def root(self) -> Node:
match_roots = [m.root for m in self.match_by_key.values()]
return get_root_node(match_roots)
@cached_property
def span(self):
# add span from this root to match root
return sum(
m.span + get_relative_depth(m.root, self.root)
for m in self.match_by_key.values()
)
def get_similarity_to(self, match: "Match"):
assert isinstance(match, self.__class__)
keys = set(self.match_by_key.keys()).intersection(
set(match.match_by_key.keys())
)
return sum(
self.match_by_key[key].get_similarity_to(match.match_by_key[key])
for key in keys
)
def __repr__(self):
return f"<{self.__class__.__name__} {self.match_by_key=}>"
class ListMatch(Match):
matches = None
def __init__(self, matches: tuple):
self.matches = matches
def __repr__(self):
return f"<{self.__class__.__name__} {self.matches=}>"
@cached_property
def root(self) -> Node:
return get_root_node([m.root for m in self.matches])
@cached_property
def span(self):
return sum(get_relative_depth(m.root, self.root) + m.span for m in self.matches)
def get_similarity_to(self, match: "Match"):
assert isinstance(match, self.__class__)
return sum(
lm1.get_similarity_to(lm2)
for lm1, lm2 in product(self.matches, match.matches)
)
class ValueMatch(Match):
node = None
extractor = None
def __init__(self, node: Node, extractor: Extractor):
self.node = node
self.extractor = extractor
def __repr__(self):
return f"<{self.__class__.__name__} {self.node=}, {self.extractor=}>"
@property
def root(self) -> Node:
return self.node
@property
def span(self):
return 0
def get_similarity_to(self, match: "Match"):
assert isinstance(match, self.__class__)
if self.extractor != match.extractor:
return 0
return get_similarity(self.node, match.node)
def generate_all_value_matches(
node: Node, item: str
) -> typing.Generator[Match, None, None]:
logging.info(f"generating all value matches ({node=}, {item=})")
for html_match in node.find_all(item):
matched_node = html_match.node
if isinstance(html_match, HTMLExactTextMatch):
extractor = TextValueExtractor()
yield ValueMatch(matched_node, extractor)
elif isinstance(html_match, HTMLAttributeMatch):
extractor = AttributeValueExtractor(html_match.attr)
yield ValueMatch(matched_node, extractor)
else:
logging.warning(
"Cannot deal with HTMLMatch type, ignoring "
f"({html_match=}, {type(html_match)=}))"
)
def is_disjoint_match_combination(matches):
"""
Check if the given matches have no overlap.
"""
return all(not m1.has_overlap(m2) for m1, m2 in combinations(matches, 2))
def is_dimensions_match(m: Match):
if not isinstance(m, ValueMatch):
return False
if not isinstance(m.extractor, AttributeValueExtractor):
return False
return m.extractor.attr in ["width", "height"]
|
