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237 lines
8.7 KiB
Python
237 lines
8.7 KiB
Python
import itertools
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import re
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from typing import (
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Any,
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Callable,
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Dict,
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Generator,
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Iterable,
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Iterator,
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List,
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Optional,
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Tuple,
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)
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from urllib.parse import urlparse
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from langchain_core.documents import Document
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from langchain_community.document_loaders.web_base import WebBaseLoader
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def _default_parsing_function(content: Any) -> str:
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return str(content.get_text())
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def _default_meta_function(meta: dict, _content: Any) -> dict:
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return {"source": meta["loc"], **meta}
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def _batch_block(iterable: Iterable, size: int) -> Generator[List[dict], None, None]:
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it = iter(iterable)
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while item := list(itertools.islice(it, size)):
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yield item
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def _extract_scheme_and_domain(url: str) -> Tuple[str, str]:
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"""Extract the scheme + domain from a given URL.
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Args:
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url (str): The input URL.
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Returns:
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return a 2-tuple of scheme and domain
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"""
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parsed_uri = urlparse(url)
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return parsed_uri.scheme, parsed_uri.netloc
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class SitemapLoader(WebBaseLoader):
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"""Load a sitemap and its URLs.
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**Security Note**: This loader can be used to load all URLs specified in a sitemap.
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If a malicious actor gets access to the sitemap, they could force
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the server to load URLs from other domains by modifying the sitemap.
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This could lead to server-side request forgery (SSRF) attacks; e.g.,
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with the attacker forcing the server to load URLs from internal
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service endpoints that are not publicly accessible. While the attacker
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may not immediately gain access to this data, this data could leak
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into downstream systems (e.g., data loader is used to load data for indexing).
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This loader is a crawler and web crawlers should generally NOT be deployed
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with network access to any internal servers.
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Control access to who can submit crawling requests and what network access
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the crawler has.
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By default, the loader will only load URLs from the same domain as the sitemap
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if the site map is not a local file. This can be disabled by setting
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restrict_to_same_domain to False (not recommended).
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If the site map is a local file, no such risk mitigation is applied by default.
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Use the filter URLs argument to limit which URLs can be loaded.
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See https://python.langchain.com/docs/security
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"""
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def __init__(
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self,
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web_path: str,
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filter_urls: Optional[List[str]] = None,
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parsing_function: Optional[Callable] = None,
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blocksize: Optional[int] = None,
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blocknum: int = 0,
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meta_function: Optional[Callable] = None,
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is_local: bool = False,
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continue_on_failure: bool = False,
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restrict_to_same_domain: bool = True,
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max_depth: int = 10,
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**kwargs: Any,
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):
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"""Initialize with webpage path and optional filter URLs.
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Args:
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web_path: url of the sitemap. can also be a local path
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filter_urls: a list of regexes. If specified, only
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URLS that match one of the filter URLs will be loaded.
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*WARNING* The filter URLs are interpreted as regular expressions.
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Remember to escape special characters if you do not want them to be
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interpreted as regular expression syntax. For example, `.` appears
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frequently in URLs and should be escaped if you want to match a literal
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`.` rather than any character.
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restrict_to_same_domain takes precedence over filter_urls when
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restrict_to_same_domain is True and the sitemap is not a local file.
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parsing_function: Function to parse bs4.Soup output
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blocksize: number of sitemap locations per block
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blocknum: the number of the block that should be loaded - zero indexed.
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Default: 0
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meta_function: Function to parse bs4.Soup output for metadata
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remember when setting this method to also copy metadata["loc"]
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to metadata["source"] if you are using this field
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is_local: whether the sitemap is a local file. Default: False
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continue_on_failure: whether to continue loading the sitemap if an error
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occurs loading a url, emitting a warning instead of raising an
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exception. Setting this to True makes the loader more robust, but also
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may result in missing data. Default: False
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restrict_to_same_domain: whether to restrict loading to URLs to the same
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domain as the sitemap. Attention: This is only applied if the sitemap
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is not a local file!
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max_depth: maximum depth to follow sitemap links. Default: 10
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"""
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if blocksize is not None and blocksize < 1:
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raise ValueError("Sitemap blocksize should be at least 1")
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if blocknum < 0:
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raise ValueError("Sitemap blocknum can not be lower then 0")
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try:
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import lxml # noqa:F401
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except ImportError:
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raise ImportError(
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"lxml package not found, please install it with `pip install lxml`"
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)
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super().__init__(web_paths=[web_path], **kwargs)
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# Define a list of URL patterns (interpreted as regular expressions) that
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# will be allowed to be loaded.
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# restrict_to_same_domain takes precedence over filter_urls when
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# restrict_to_same_domain is True and the sitemap is not a local file.
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self.allow_url_patterns = filter_urls
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self.restrict_to_same_domain = restrict_to_same_domain
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self.parsing_function = parsing_function or _default_parsing_function
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self.meta_function = meta_function or _default_meta_function
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self.blocksize = blocksize
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self.blocknum = blocknum
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self.is_local = is_local
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self.continue_on_failure = continue_on_failure
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self.max_depth = max_depth
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def parse_sitemap(self, soup: Any, *, depth: int = 0) -> List[dict]:
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"""Parse sitemap xml and load into a list of dicts.
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Args:
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soup: BeautifulSoup object.
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depth: current depth of the sitemap. Default: 0
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Returns:
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List of dicts.
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"""
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if depth >= self.max_depth:
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return []
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els: List[Dict] = []
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for url in soup.find_all("url"):
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loc = url.find("loc")
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if not loc:
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continue
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# Strip leading and trailing whitespace and newlines
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loc_text = loc.text.strip()
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if self.restrict_to_same_domain and not self.is_local:
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if _extract_scheme_and_domain(loc_text) != _extract_scheme_and_domain(
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self.web_path
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):
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continue
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if self.allow_url_patterns and not any(
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re.match(regexp_pattern, loc_text)
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for regexp_pattern in self.allow_url_patterns
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):
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continue
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els.append(
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{
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tag: prop.text
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for tag in ["loc", "lastmod", "changefreq", "priority"]
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if (prop := url.find(tag))
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}
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)
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for sitemap in soup.find_all("sitemap"):
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loc = sitemap.find("loc")
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if not loc:
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continue
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soup_child = self.scrape_all([loc.text], "xml")[0]
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els.extend(self.parse_sitemap(soup_child, depth=depth + 1))
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return els
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def lazy_load(self) -> Iterator[Document]:
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"""Load sitemap."""
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if self.is_local:
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try:
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import bs4
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except ImportError:
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raise ImportError(
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"beautifulsoup4 package not found, please install it"
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" with `pip install beautifulsoup4`"
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)
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fp = open(self.web_path)
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soup = bs4.BeautifulSoup(fp, "xml")
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else:
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soup = self._scrape(self.web_path, parser="xml")
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els = self.parse_sitemap(soup)
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if self.blocksize is not None:
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elblocks = list(_batch_block(els, self.blocksize))
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blockcount = len(elblocks)
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if blockcount - 1 < self.blocknum:
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raise ValueError(
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"Selected sitemap does not contain enough blocks for given blocknum"
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)
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else:
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els = elblocks[self.blocknum]
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results = self.scrape_all([el["loc"].strip() for el in els if "loc" in el])
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for i, result in enumerate(results):
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yield Document(
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page_content=self.parsing_function(result),
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metadata=self.meta_function(els[i], result),
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)
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