# pylint:disable-msg=E0611,I1101
"""
Functions grounding on third-party software.
"""
import logging
from typing import Any, Tuple
# third-party
from justext.core import ParagraphMaker, classify_paragraphs, revise_paragraph_classification # type: ignore
from justext.utils import get_stoplist, get_stoplists # type: ignore
from lxml.etree import _Element, Element, strip_tags, tostring
from lxml.html import HtmlElement
# own
from .baseline import basic_cleaning
from .htmlprocessing import convert_tags, prune_unwanted_nodes, tree_cleaning
from .readability_lxml import Document as ReadabilityDocument # fork
from .settings import JUSTEXT_LANGUAGES
from .utils import fromstring_bytes, trim
from .xml import TEI_VALID_TAGS
from .xpaths import OVERALL_DISCARD_XPATH
LOGGER = logging.getLogger(__name__)
JT_STOPLIST = None
SANITIZED_XPATH = './/aside|.//audio|.//button|.//fieldset|.//figure|.//footer|.//iframe|.//input|.//label|.//link|.//nav|.//noindex|.//noscript|.//object|.//option|.//select|.//source|.//svg|.//time'
[docs]
def try_readability(htmlinput: HtmlElement) -> HtmlElement:
'''Safety net: try with the generic algorithm readability'''
# defaults: min_text_length=25, retry_length=250
try:
doc = ReadabilityDocument(htmlinput, min_text_length=25, retry_length=250)
# force conversion to utf-8 (see #319)
summary = fromstring_bytes(doc.summary())
return summary if summary is not None else HtmlElement()
except Exception as err:
LOGGER.warning('readability_lxml failed: %s', err)
return HtmlElement()
def compare_extraction(tree: HtmlElement, backup_tree: HtmlElement, body: _Element, text: str, len_text: int, options: Any) -> Tuple[_Element, str, int]:
'''Decide whether to choose own or external extraction
based on a series of heuristics'''
# bypass for recall
if options.focus == "recall" and len_text > options.min_extracted_size * 10:
return body, text, len_text
use_readability, jt_result = False, False
# prior cleaning
if options.focus == "precision":
backup_tree = prune_unwanted_nodes(backup_tree, OVERALL_DISCARD_XPATH)
# try with readability
temppost_algo = try_readability(backup_tree)
# unicode fix necessary on certain systems (#331)
algo_text = trim(tostring(temppost_algo, method='text', encoding='utf-8').decode('utf-8'))
len_algo = len(algo_text)
# compare
LOGGER.debug('extracted length: %s (algorithm) %s (extraction)', len_algo, len_text)
# conditions to use alternative algorithms
if len_algo in (0, len_text):
use_readability = False
elif len_text == 0 and len_algo > 0:
use_readability = True
elif len_text > 2 * len_algo:
use_readability = False
# quick fix for https://github.com/adbar/trafilatura/issues/632
elif len_algo > 2 * len_text and not algo_text.startswith("{"):
use_readability = True
# borderline cases
elif not body.xpath('.//p//text()') and len_algo > options.min_extracted_size * 2:
use_readability = True
elif len(body.findall('.//table')) > len(body.findall('.//p')) and len_algo > options.min_extracted_size * 2:
use_readability = True
# https://github.com/adbar/trafilatura/issues/354
elif options.focus == "recall" and not body.xpath('.//head') and temppost_algo.xpath('.//h2|.//h3|.//h4') and len_algo > len_text:
use_readability = True
else:
LOGGER.debug('extraction values: %s %s for %s', len_text, len_algo, options.source)
use_readability = False
# apply decision
if use_readability:
body, text, len_text = temppost_algo, algo_text, len_algo
LOGGER.debug('using generic algorithm: %s', options.source)
else:
LOGGER.debug('using custom extraction: %s', options.source)
# override faulty extraction: try with justext
if body.xpath(SANITIZED_XPATH) or len_text < options.min_extracted_size: # body.find(...)
LOGGER.debug('unclean document triggering justext examination: %s', options.source)
body2, text2, len_text2 = justext_rescue(tree, options)
jt_result = bool(text2)
# prevent too short documents from replacing the main text
if text2 and not len_text > 4*len_text2: # threshold could be adjusted
LOGGER.debug('using justext, length: %s', len_text2)
body, text, len_text = body2, text2, len_text2
# post-processing: remove unwanted sections
if use_readability and not jt_result:
body, text, len_text = sanitize_tree(body, options) # type: ignore[arg-type]
return body, text, len_text
def jt_stoplist_init() -> Tuple[str]:
'Retrieve and return the content of all JusText stoplists'
global JT_STOPLIST
stoplist = set()
for language in get_stoplists():
stoplist.update(get_stoplist(language))
JT_STOPLIST = tuple(stoplist)
return JT_STOPLIST
def custom_justext(tree: HtmlElement, stoplist: Tuple[str]) -> Any:
'Customized version of JusText processing'
paragraphs = ParagraphMaker.make_paragraphs(tree)
classify_paragraphs(paragraphs, stoplist, 50, 150, 0.1, 0.2, 0.25, True)
revise_paragraph_classification(paragraphs, 150)
return paragraphs
[docs]
def try_justext(tree: HtmlElement, url: str, target_language: str) -> _Element:
'''Second safety net: try with the generic algorithm justext'''
# init
result_body = Element('body')
# determine language
if target_language in JUSTEXT_LANGUAGES:
justext_stoplist = get_stoplist(JUSTEXT_LANGUAGES[target_language])
else:
justext_stoplist = JT_STOPLIST or jt_stoplist_init()
# extract
try:
paragraphs = custom_justext(tree, justext_stoplist)
except Exception as err:
LOGGER.error('justext %s %s', err, url)
else:
for paragraph in paragraphs:
if paragraph.is_boilerplate:
continue
#if duplicate_test(paragraph) is not True:
elem, elem.text = Element('p'), paragraph.text
result_body.append(elem)
return result_body
def justext_rescue(tree: HtmlElement, options: Any) -> Tuple[_Element, str, int]:
'''Try to use justext algorithm as a second fallback'''
# additional cleaning
tree = basic_cleaning(tree)
# proceed
temppost_algo = try_justext(tree, options.url, options.lang)
temp_text = trim(' '.join(temppost_algo.itertext()))
return temppost_algo, temp_text, len(temp_text)
def sanitize_tree(tree: HtmlElement, options: Any) -> Tuple[HtmlElement, str, int]:
'''Convert and sanitize the output from the generic algorithm (post-processing)'''
# 1. clean
cleaned_tree = tree_cleaning(tree, options)
if options.links is False:
strip_tags(cleaned_tree, 'a')
strip_tags(cleaned_tree, 'span')
# 2. convert
cleaned_tree = convert_tags(cleaned_tree, options)
for elem in cleaned_tree.iter('td', 'th', 'tr'):
# elem.text, elem.tail = trim(elem.text), trim(elem.tail)
# finish table conversion
if elem.tag == 'tr':
elem.tag = 'row'
elif elem.tag in ('td', 'th'):
if elem.tag == 'th':
elem.set('role', 'head')
elem.tag = 'cell'
# 3. sanitize
sanitization_list = [
tagname
for tagname in [element.tag for element in set(cleaned_tree.iter('*'))]
if tagname not in TEI_VALID_TAGS
]
strip_tags(cleaned_tree, *sanitization_list)
# 4. return
text = trim(' '.join(cleaned_tree.itertext()))
return cleaned_tree, text, len(text)
