Source code for scrapy.linkextractors.lxmlhtml

Link extractor based on lxml.html

import logging
import operator
from functools import partial
from typing import (
from urllib.parse import urljoin, urlparse

from lxml import etree  # nosec
from lxml.html import HtmlElement  # nosec
from parsel.csstranslator import HTMLTranslator
from w3lib.html import strip_html5_whitespace
from w3lib.url import canonicalize_url, safe_url_string

from scrapy import Selector
from scrapy.http import TextResponse
from import Link
from scrapy.linkextractors import IGNORED_EXTENSIONS, _is_valid_url, _matches, re
from scrapy.utils.misc import arg_to_iter, rel_has_nofollow
from scrapy.utils.python import unique as unique_list
from scrapy.utils.response import get_base_url
from scrapy.utils.url import url_has_any_extension, url_is_from_any_domain

logger = logging.getLogger(__name__)

# from lxml/src/lxml/html/

_collect_string_content = etree.XPath("string()")

def _nons(tag: Any) -> Any:
    if isinstance(tag, str):
        if tag[0] == "{" and tag[1 : len(XHTML_NAMESPACE) + 1] == XHTML_NAMESPACE:
            return tag.split("}")[-1]
    return tag

def _identity(x: Any) -> Any:
    return x

def _canonicalize_link_url(link: Link) -> str:
    return canonicalize_url(link.url, keep_fragments=True)

class LxmlParserLinkExtractor:
    def __init__(
        tag: Union[str, Callable[[str], bool]] = "a",
        attr: Union[str, Callable[[str], bool]] = "href",
        process: Optional[Callable[[Any], Any]] = None,
        unique: bool = False,
        strip: bool = True,
        canonicalized: bool = False,
        # mypy doesn't infer types for operator.* and also for partial()
        self.scan_tag: Callable[[str], bool] = (
            if callable(tag)
            else cast(Callable[[str], bool], partial(operator.eq, tag))
        self.scan_attr: Callable[[str], bool] = (
            if callable(attr)
            else cast(Callable[[str], bool], partial(operator.eq, attr))
        self.process_attr: Callable[[Any], Any] = (
            process if callable(process) else _identity
        self.unique: bool = unique
        self.strip: bool = strip
        self.link_key: Callable[[Link], str] = (
            cast(Callable[[Link], str], operator.attrgetter("url"))
            if canonicalized
            else _canonicalize_link_url

    def _iter_links(
        self, document: HtmlElement
    ) -> Iterable[Tuple[HtmlElement, str, str]]:
        for el in document.iter(etree.Element):
            if not self.scan_tag(_nons(el.tag)):
            attribs = el.attrib
            for attrib in attribs:
                if not self.scan_attr(attrib):
                yield el, attrib, attribs[attrib]

    def _extract_links(
        selector: Selector,
        response_url: str,
        response_encoding: str,
        base_url: str,
    ) -> List[Link]:
        links: List[Link] = []
        # hacky way to get the underlying lxml parsed document
        for el, attr, attr_val in self._iter_links(selector.root):
            # pseudo lxml.html.HtmlElement.make_links_absolute(base_url)
                if self.strip:
                    attr_val = strip_html5_whitespace(attr_val)
                attr_val = urljoin(base_url, attr_val)
            except ValueError:
                continue  # skipping bogus links
                url = self.process_attr(attr_val)
                if url is None:
                url = safe_url_string(url, encoding=response_encoding)
            except ValueError:
                logger.debug(f"Skipping extraction of link with bad URL {url!r}")

            # to fix relative links after process_value
            url = urljoin(response_url, url)
            link = Link(
                _collect_string_content(el) or "",
        return self._deduplicate_if_needed(links)

    def extract_links(self, response: TextResponse) -> List[Link]:
        base_url = get_base_url(response)
        return self._extract_links(
            response.selector, response.url, response.encoding, base_url

    def _process_links(self, links: List[Link]) -> List[Link]:
        """Normalize and filter extracted links

        The subclass should override it if necessary
        return self._deduplicate_if_needed(links)

    def _deduplicate_if_needed(self, links: List[Link]) -> List[Link]:
        if self.unique:
            return unique_list(links, key=self.link_key)
        return links

_RegexT = Union[str, Pattern[str]]
_RegexOrSeveralT = Union[_RegexT, Iterable[_RegexT]]

[docs]class LxmlLinkExtractor: _csstranslator = HTMLTranslator() def __init__( self, allow: _RegexOrSeveralT = (), deny: _RegexOrSeveralT = (), allow_domains: Union[str, Iterable[str]] = (), deny_domains: Union[str, Iterable[str]] = (), restrict_xpaths: Union[str, Iterable[str]] = (), tags: Union[str, Iterable[str]] = ("a", "area"), attrs: Union[str, Iterable[str]] = ("href",), canonicalize: bool = False, unique: bool = True, process_value: Optional[Callable[[Any], Any]] = None, deny_extensions: Union[str, Iterable[str], None] = None, restrict_css: Union[str, Iterable[str]] = (), strip: bool = True, restrict_text: Optional[_RegexOrSeveralT] = None, ): tags, attrs = set(arg_to_iter(tags)), set(arg_to_iter(attrs)) self.link_extractor = LxmlParserLinkExtractor( tag=partial(operator.contains, tags), attr=partial(operator.contains, attrs), unique=unique, process=process_value, strip=strip, canonicalized=not canonicalize, ) self.allow_res: List[Pattern[str]] = self._compile_regexes(allow) self.deny_res: List[Pattern[str]] = self._compile_regexes(deny) self.allow_domains: Set[str] = set(arg_to_iter(allow_domains)) self.deny_domains: Set[str] = set(arg_to_iter(deny_domains)) self.restrict_xpaths: Tuple[str, ...] = tuple(arg_to_iter(restrict_xpaths)) self.restrict_xpaths += tuple( map(self._csstranslator.css_to_xpath, arg_to_iter(restrict_css)) ) if deny_extensions is None: deny_extensions = IGNORED_EXTENSIONS self.canonicalize: bool = canonicalize self.deny_extensions: Set[str] = {"." + e for e in arg_to_iter(deny_extensions)} self.restrict_text: List[Pattern[str]] = self._compile_regexes(restrict_text) @staticmethod def _compile_regexes(value: Optional[_RegexOrSeveralT]) -> List[Pattern[str]]: return [ x if isinstance(x, re.Pattern) else re.compile(x) for x in arg_to_iter(value) ] def _link_allowed(self, link: Link) -> bool: if not _is_valid_url(link.url): return False if self.allow_res and not _matches(link.url, self.allow_res): return False if self.deny_res and _matches(link.url, self.deny_res): return False parsed_url = urlparse(link.url) if self.allow_domains and not url_is_from_any_domain( parsed_url, self.allow_domains ): return False if self.deny_domains and url_is_from_any_domain(parsed_url, self.deny_domains): return False if self.deny_extensions and url_has_any_extension( parsed_url, self.deny_extensions ): return False if self.restrict_text and not _matches(link.text, self.restrict_text): return False return True def matches(self, url: str) -> bool: if self.allow_domains and not url_is_from_any_domain(url, self.allow_domains): return False if self.deny_domains and url_is_from_any_domain(url, self.deny_domains): return False allowed = ( ( for regex in self.allow_res) if self.allow_res else [True] ) denied = ( for regex in self.deny_res) if self.deny_res else [] return any(allowed) and not any(denied) def _process_links(self, links: List[Link]) -> List[Link]: links = [x for x in links if self._link_allowed(x)] if self.canonicalize: for link in links: link.url = canonicalize_url(link.url) links = self.link_extractor._process_links(links) return links def _extract_links(self, *args: Any, **kwargs: Any) -> List[Link]: return self.link_extractor._extract_links(*args, **kwargs)