Source code for scrapy.linkextractors.lxmlhtml

Link extractor based on lxml.html
import operator
from functools import partial
from urllib.parse import urljoin

import lxml.etree as etree
from w3lib.html import strip_html5_whitespace
from w3lib.url import canonicalize_url, safe_url_string

from import Link
from scrapy.linkextractors import FilteringLinkExtractor
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 lxml/src/lxml/html/

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

def _nons(tag):
    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):
    return x

def _canonicalize_link_url(link):
    return canonicalize_url(link.url, keep_fragments=True)

class LxmlParserLinkExtractor:
    def __init__(
        self, tag="a", attr="href", process=None, unique=False, strip=True, canonicalized=False
        self.scan_tag = tag if callable(tag) else partial(operator.eq, tag)
        self.scan_attr = attr if callable(attr) else partial(operator.eq, attr)
        self.process_attr = process if callable(process) else _identity
        self.unique = unique
        self.strip = strip
        self.link_key = operator.attrgetter("url") if canonicalized else _canonicalize_link_url

    def _iter_links(self, document):
        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(self, selector, response_url, response_encoding, base_url):
        links = []
        # 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)
            # to fix relative links after process_value
            url = urljoin(response_url, url)
            link = Link(url, _collect_string_content(el) or u'',
        return self._deduplicate_if_needed(links)

    def extract_links(self, response):
        base_url = get_base_url(response)
        return self._extract_links(response.selector, response.url, response.encoding, base_url)

    def _process_links(self, links):
        """ Normalize and filter extracted links

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

    def _deduplicate_if_needed(self, links):
        if self.unique:
            return unique_list(links, key=self.link_key)
        return links

[docs]class LxmlLinkExtractor(FilteringLinkExtractor): def __init__( self, allow=(), deny=(), allow_domains=(), deny_domains=(), restrict_xpaths=(), tags=('a', 'area'), attrs=('href',), canonicalize=False, unique=True, process_value=None, deny_extensions=None, restrict_css=(), strip=True, restrict_text=None, ): tags, attrs = set(arg_to_iter(tags)), set(arg_to_iter(attrs)) lx = LxmlParserLinkExtractor( tag=partial(operator.contains, tags), attr=partial(operator.contains, attrs), unique=unique, process=process_value, strip=strip, canonicalized=canonicalize ) super(LxmlLinkExtractor, self).__init__( link_extractor=lx, allow=allow, deny=deny, allow_domains=allow_domains, deny_domains=deny_domains, restrict_xpaths=restrict_xpaths, restrict_css=restrict_css, canonicalize=canonicalize, deny_extensions=deny_extensions, restrict_text=restrict_text, )