# pylint:disable-msg=E0611
"""
Functions related to the main Trafilatura extractor.
"""
import logging
import re # import regex as re
from copy import deepcopy
from typing import Any
from urllib.parse import urljoin
from lxml.etree import Element, SubElement, _Element, strip_elements, strip_tags, tostring
from lxml.html import HtmlElement
# own
from .htmlprocessing import (
delete_by_link_density,
handle_textnode,
link_density_test_tables,
process_node,
prune_unwanted_nodes,
)
from .settings import INLINE_CARRIED, TAG_CATALOG, Extractor
from .utils import FORMATTING_PROTECTED, is_image_file, text_chars_test, trim
from .xml import delete_element
from .xpaths import (
BODY_XPATH,
COMMENTS_DISCARD_XPATH,
COMMENTS_XPATH,
DISCARD_IMAGE_ELEMENTS,
OVERALL_DISCARD_XPATH,
PRECISION_DISCARD_XPATH,
TEASER_DISCARD_XPATH,
)
LOGGER = logging.getLogger(__name__)
P_FORMATTING = {"hi", "ref"}
TABLE_ELEMS = {"td", "th"}
TABLE_ALL = TABLE_ELEMS | P_FORMATTING | {"del"}
FORMATTING = P_FORMATTING | {"del", "span"}
# meaningful internal attributes to carry onto a rewired sub-element (drop stray class/style/width/etc.)
KEEP_ATTRS = {"rend", "role", "target", "src", "alt", "title"}
# min text length for an adjacent-duplicate element to be treated as an extraction artifact and dropped
DUPLICATE_ADJACENT_LIMIT = 50
CODES_QUOTES = {"code", "quote"}
NOT_AT_THE_END = {"head", "ref"}
# tags allowed inside a blockquote paragraph
_QUOTE_TAGS = set(TAG_CATALOG) | {"ref", "graphic"}
def _wraps_inline(element: _Element) -> bool:
"A formatting element whose children must be carried verbatim: ref, or hi/del wrapping inline content."
return len(element) > 0 and (element.tag == "ref" or any(c.tag in INLINE_CARRIED for c in element))
def _log_event(msg: str, tag: Any, text: bytes | str | None) -> None:
"Format extraction event for debugging purposes."
LOGGER.debug("%s: %s %s", msg, tag, trim(text or "") or "None")
def handle_titles(element: _Element, options: Extractor) -> _Element | None:
"""Process head elements (titles)"""
if len(element) == 0:
# maybe needs attention?
# if element.tail and re.search(r'\w', element.tail):
# LOGGER.debug('tail in title, stripping: %s', element.tail)
# element.tail = None
title = process_node(element, options)
# children
else:
title = deepcopy(element)
# list instead of element.iter('*')
# TODO: write tests for it and check
for child in list(element):
# if child.tag not in potential_tags:
# LOGGER.debug('unexpected in title: %s %s %s', child.tag, child.text, child.tail)
# continue
processed_child = handle_textnode(child, options, comments_fix=False)
if processed_child is not None:
title.append(processed_child)
child.tag = "done"
if title is not None and text_chars_test("".join(title.itertext())) is True:
return title
return None
def handle_formatting(element: _Element, options: Extractor) -> _Element | None:
"""Process formatting elements (b, i, etc. converted to hi) found
outside of paragraphs"""
formatting = process_node(element, options)
if formatting is None: # and len(element) == 0
return None
# repair orphan elements
# if formatting is None:
# formatting = Element(element.tag)
# return None
# if len(element) > 0:
# for child in element.iter('*'):
# if child.tag not in potential_tags:
# LOGGER.debug('unexpected in title: %s %s %s', child.tag, child.text, child.tail)
# continue
# processed_child = handle_textnode(child, options, comments_fix=False)
# if processed_child is not None:
# formatting.append(processed_child)
# child.tag = 'done'
# if text_chars_test(element.text) is True:
# processed_child.text = trim(element.text)
# if text_chars_test(element.tail) is True:
# processed_child.tail = trim(element.tail)
# if len(element) == 0:
# processed_element = process_node(element, options)
# children
# else:
# processed_element = Element(element.tag)
# processed_element.text, processed_element.tail = element.text, element.tail
# for child in element.iter('*'):
# processed_child = handle_textnode(child, options, comments_fix=False)
# if processed_child is not None:
# processed_element.append(processed_child)
# child.tag = 'done'
# repair orphan elements
# shorter code but triggers warning:
# parent = element.getparent() or element.getprevious()
parent = element.getparent()
if parent is None:
parent = element.getprevious()
if parent is None or parent.tag not in FORMATTING_PROTECTED:
processed_element = Element("p")
processed_element.insert(0, formatting)
else:
processed_element = formatting
return processed_element
def process_nested_elements(child: _Element, new_child_elem: _Element, options: Extractor) -> None:
"Iterate through an element child and rewire its descendants."
new_child_elem.text = child.text
for subelem in child.iterdescendants("*"):
if subelem.tag == "list":
processed_subchild = handle_lists(subelem, options)
if processed_subchild is not None:
new_child_elem.append(processed_subchild)
elif subelem.tag in INLINE_CARRIED:
define_newelem(subelem, new_child_elem, keep_children=True)
else:
processed_subchild = handle_textnode(subelem, options, comments_fix=False)
if processed_subchild is not None:
define_newelem(processed_subchild, new_child_elem)
subelem.tag = "done"
def update_elem_rendition(elem: _Element, new_elem: _Element) -> None:
"Copy the rend attribute from an existing element to a new one."
if rend_attr := elem.get("rend"):
new_elem.set("rend", rend_attr)
def is_text_element(elem: _Element) -> bool:
"Find if the element contains text."
return elem is not None and text_chars_test("".join(elem.itertext())) is True
def define_newelem(processed_elem: _Element | None, orig_elem: _Element, keep_children: bool = False) -> None:
"Create a new sub-element, optionally carrying its inline children (INLINE_CARRIED)."
if processed_elem is not None:
childelem = SubElement(orig_elem, processed_elem.tag)
childelem.text, childelem.tail = processed_elem.text, processed_elem.tail
for key, value in processed_elem.attrib.items():
if key in KEEP_ATTRS:
childelem.set(key, value)
if keep_children:
for sub in processed_elem:
if sub.tag in INLINE_CARRIED:
define_newelem(sub, childelem, keep_children=True)
# mark only the carried subtree done; non-carried siblings (e.g. nested <p>) stay processable
for carried in sub.iter("*"):
carried.tag = "done"
def handle_lists(element: _Element, options: Extractor) -> _Element | None:
"Process lists elements including their descendants."
processed_element = Element(element.tag)
if element.text is not None and element.text.strip():
new_child_elem = SubElement(processed_element, "item")
new_child_elem.text = element.text
# if element.tail is not None:
# processed_element.tail = element.text
for child in element.iterdescendants("item"):
new_child_elem = Element("item")
if len(child) == 0:
processed_child = process_node(child, options)
if processed_child is not None:
new_child_elem.text = processed_child.text or ""
if processed_child.tail and processed_child.tail.strip():
new_child_elem.text += " " + processed_child.tail
processed_element.append(new_child_elem)
else:
process_nested_elements(child, new_child_elem, options)
if child.tail is not None and child.tail.strip():
new_child_elem_children = [el for el in new_child_elem if el.tag != "done"]
if new_child_elem_children:
last_subchild = new_child_elem_children[-1]
if last_subchild.tail is None or not last_subchild.tail.strip():
last_subchild.tail = child.tail
else:
last_subchild.tail += " " + child.tail
if new_child_elem.text or len(new_child_elem) > 0:
update_elem_rendition(child, new_child_elem)
processed_element.append(new_child_elem)
child.tag = "done"
element.tag = "done"
# test if it has children and text. Avoid double tags??
if is_text_element(processed_element):
update_elem_rendition(element, processed_element)
return processed_element
return None
def is_code_block_element(element: _Element) -> bool:
"Check if it is a code element according to common structural markers."
# pip
if element.get("lang") or element.tag == "code":
return True
# GitHub
parent = element.getparent()
if parent is not None and "highlight" in parent.get("class", ""):
return True
# highlightjs
code = element.find("code")
if code is not None and len(element) == 1 and not (element.text or "").strip() and not (code.tail or "").strip():
return True
return False
def handle_code_blocks(element: _Element) -> _Element:
"Turn element into a properly tagged code block."
processed_element = deepcopy(element)
for child in element.iter("*"):
child.tag = "done"
processed_element.tag = "code"
return processed_element
def handle_quotes(element: _Element, options: Extractor) -> _Element | None:
"Process quotes elements."
if is_code_block_element(element):
return handle_code_blocks(element)
processed_element = Element(element.tag)
processed_element.text = element.text
for child in element.iterdescendants():
if child.tag == "graphic":
processed_child = handle_image(child, options)
define_newelem(processed_child, processed_element)
elif child.tag == "p" and len(child) > 0:
processed_child = handle_paragraphs(child, _QUOTE_TAGS, options)
if processed_child is not None:
processed_element.append(processed_child)
elif child.tag in INLINE_CARRIED:
define_newelem(child, processed_element, keep_children=True)
else:
processed_child = process_node(child, options)
define_newelem(processed_child, processed_element)
child.tag = "done"
if is_text_element(processed_element):
# avoid double/nested tags
strip_tags(processed_element, "quote")
return processed_element
return None
def handle_other_elements(element: _Element, potential_tags: set[str], options: Extractor) -> _Element | None:
"Handle diverse or unknown elements in the scope of relevant tags."
# handle w3schools code
if element.tag == "div" and "w3-code" in element.get("class", ""):
return handle_code_blocks(element)
# delete unwanted
if element.tag not in potential_tags:
if element.tag != "done":
_log_event("discarding element", element.tag, element.text)
return None
if element.tag == "div":
# make a copy and prune it in case it contains sub-elements handled on their own?
# divcopy = deepcopy(element)
processed_element = handle_textnode(element, options, comments_fix=False, preserve_spaces=True)
if processed_element is not None and text_chars_test(processed_element.text) is True:
processed_element.attrib.clear()
# small div-correction # could be moved elsewhere
if processed_element.tag == "div":
processed_element.tag = "p"
# insert
return processed_element
return None
def handle_paragraphs(element: _Element, potential_tags: set[str], options: Extractor) -> _Element | None:
"Process paragraphs along with their children, trim and clean the content."
element.attrib.clear() # todo: test if necessary
# strip_tags(element, 'p') # change in precision due to spaces?
# no children
if len(element) == 0:
return process_node(element, options)
# children
processed_element = Element(element.tag)
for child in element.iter("*"):
if child.tag not in potential_tags and child.tag != "done":
_log_event("unexpected in p", child.tag, child.text)
continue
# spacing = child.tag in SPACING_PROTECTED # todo: outputformat.startswith('xml')?
# todo: act on spacing here?
processed_child = handle_textnode(child, options, comments_fix=False, preserve_spaces=True)
if processed_child is not None:
# todo: needing attention!
if processed_child.tag == "p":
_log_event("extra in p", "p", processed_child.text)
if processed_element.text:
processed_element.text += " " + (processed_child.text or "")
else:
processed_element.text = processed_child.text
child.tag = "done"
continue
# handle formatting
newsub = Element(child.tag)
if processed_child.tag in P_FORMATTING:
# carry inline children verbatim (ref/hi/del wrapping formatting)
if _wraps_inline(processed_child):
define_newelem(processed_child, processed_element, keep_children=True)
child.tag = "done"
continue
# check depth and clean
if len(processed_child) > 0:
for item in processed_child: # children are lists
if item.tag == "lb" and item.tail:
item.tail = " " + item.tail.lstrip()
elif item.text is not None and text_chars_test(item.text):
item.text = " " + item.text
strip_tags(processed_child, item.tag) # type: ignore[arg-type]
# correct attributes
if child.tag == "hi":
newsub.set("rend", child.get("rend", ""))
elif child.tag == "ref":
if child.get("target") is not None:
newsub.set("target", child.get("target", ""))
# handle line breaks
# elif processed_child.tag == 'lb':
# try:
# processed_child.tail = process_node(child, options).tail
# except AttributeError: # no text
# pass
# prepare text
# todo: to be moved to handle_textnode()
# if text_chars_test(processed_child.text) is False:
# processed_child.text = ''
# if text_chars_test(processed_child.tail) is False:
# processed_child.tail = ''
# if there are already children
# if len(processed_element) > 0:
# if text_chars_test(processed_child.tail) is True:
# newsub.tail = processed_child.text + processed_child.tail
# else:
# newsub.tail = processed_child.text
newsub.text, newsub.tail = processed_child.text, processed_child.tail
if processed_child.tag == "graphic":
image_elem = handle_image(processed_child, options)
if image_elem is not None:
newsub = image_elem
processed_element.append(newsub)
child.tag = "done"
# finish
if len(processed_element) > 0:
last_elem = processed_element[-1]
# clean trailing lb-elements
if last_elem.tag == "lb" and last_elem.tail is None:
delete_element(last_elem)
return processed_element
if processed_element.text:
return processed_element
_log_event("discarding element:", "p", tostring(processed_element))
return None
def define_cell_type(is_header: bool) -> _Element:
"Determine cell element type and mint new element."
# define tag
cell_element = Element("cell")
if is_header:
cell_element.set("role", "head")
return cell_element
def _colspan(cell: _Element) -> int:
"Parse a cell's colspan, defaulting to 1 for a missing or non-numeric value."
value = cell.get("colspan", "1")
# isdecimal, not isdigit: int() rejects the superscripts isdigit() admits
return int(value) if value.isdecimal() else 1
def _row_has_content(row: _Element) -> bool:
"Whether any cell in a row carries text or children."
return any(cell.text or len(cell) > 0 for cell in row)
def handle_table(table_elem: _Element, potential_tags: set[str], options: Extractor) -> _Element | None:
"Process single table element."
newtable = Element("table")
# strip these structural elements
strip_tags(table_elem, "thead", "tbody", "tfoot")
# maximum number of columns per row, including colspan
max_cols = max(
(sum(_colspan(td) for td in tr.iter(TABLE_ELEMS)) for tr in table_elem.iter("tr")),
default=0,
)
# explore sub-elements
seen_header_row = False
seen_header = False
# every row carries the table's column count so short rows pad consistently (no last-row exception)
span_attr = str(max_cols) if max_cols > 1 else ""
newrow = Element("row")
if span_attr:
newrow.set("span", span_attr)
for subelement in table_elem.iterdescendants():
if not isinstance(subelement.tag, str): # skip comments / PIs (non-writable .tag)
continue
if subelement.tag == "tr":
# flush the previous row (dropping it if all cells are empty), then start a fresh one
if len(newrow) > 0:
if _row_has_content(newrow):
newtable.append(newrow)
newrow = Element("row")
if span_attr:
newrow.set("span", span_attr)
seen_header_row = seen_header_row or seen_header
elif subelement.tag in TABLE_ELEMS:
is_header = subelement.tag == "th" and not seen_header_row
seen_header = seen_header or is_header
new_child_elem = define_cell_type(is_header)
# process
if len(subelement) == 0:
processed_cell = process_node(subelement, options)
if processed_cell is not None:
new_child_elem.text, new_child_elem.tail = processed_cell.text, processed_cell.tail
else:
# proceed with iteration, fix for nested elements
new_child_elem.text, new_child_elem.tail = subelement.text, subelement.tail
subelement.tag = "done"
for child in subelement.iterdescendants():
if not isinstance(child.tag, str): # skip comments / PIs
continue
if child.tag in TABLE_ALL:
# todo: define attributes properly
if child.tag in TABLE_ELEMS:
child.tag = "cell"
processed_subchild = handle_textnode(child, options, preserve_spaces=True, comments_fix=True)
# lists in cells only in recall mode: keeping them otherwise is noise (measured precision loss)
elif child.tag == "list" and options.focus == "recall":
processed_subchild = handle_lists(child, options)
if processed_subchild is not None:
new_child_elem.append(processed_subchild)
processed_subchild = None # don't handle it anymore
else:
processed_subchild = handle_textelem(child, potential_tags.union(["div"]), options)
define_newelem(processed_subchild, new_child_elem, keep_children=True)
child.tag = "done"
# add to tree (keep empty cells so column positions stay aligned)
newrow.append(new_child_elem)
# beware of nested tables
elif subelement.tag == "table":
break
# cleanup
subelement.tag = "done"
# end of processing
if _row_has_content(newrow):
newtable.append(newrow)
if len(newtable) > 0:
return newtable
return None
def handle_image(element: _Element | None, options: Extractor | None = None) -> _Element | None:
"Process image elements and their relevant attributes."
if element is None:
return None
processed_element = Element(element.tag)
for attr in ("data-src", "src"):
src = element.get(attr, "")
if is_image_file(src):
processed_element.set("src", src)
break
else:
# take the first corresponding attribute
for attr, value in element.attrib.items():
if attr.startswith("data-src") and is_image_file(value):
processed_element.set("src", value)
break
# additional data
if alt_attr := element.get("alt"):
processed_element.set("alt", alt_attr)
if title_attr := element.get("title"):
processed_element.set("title", title_attr)
# don't return empty elements or elements without source, just None
if not processed_element.attrib or not processed_element.get("src"):
return None
# post-processing: URLs
link = processed_element.get("src", "")
if not link.startswith("http"):
if options is not None and options.url is not None:
link = urljoin(options.url, link)
else:
link = re.sub(r"^//", "http://", link)
processed_element.set("src", link)
processed_element.tail = element.tail
return processed_element
def handle_textelem(element: _Element, potential_tags: set[str], options: Extractor) -> _Element | None:
"""Process text element and determine how to deal with its content"""
new_element = None
# bypass: nested elements
if element.tag == "list":
new_element = handle_lists(element, options)
elif element.tag in CODES_QUOTES:
new_element = handle_quotes(element, options)
elif element.tag == "head":
new_element = handle_titles(element, options)
elif element.tag == "p":
new_element = handle_paragraphs(element, potential_tags, options)
elif element.tag == "lb":
if text_chars_test(element.tail) is True:
this_element = process_node(element, options)
if this_element is not None:
new_element = Element("p")
new_element.text = this_element.tail
elif element.tag in FORMATTING:
new_element = handle_formatting(element, options) # process_node(element, options)
elif element.tag == "table" and "table" in potential_tags:
new_element = handle_table(element, potential_tags, options)
elif element.tag == "graphic" and "graphic" in potential_tags:
new_element = handle_image(element, options)
else:
# other elements (div, ??, ??)
new_element = handle_other_elements(element, potential_tags, options)
return new_element
def recover_wild_text(
tree: HtmlElement, result_body: _Element, options: Extractor, potential_tags: set[str] | None = None
) -> _Element:
"""Look for all previously unconsidered wild elements, including outside of the determined
frame and throughout the document to recover potentially missing text parts"""
LOGGER.debug("Recovering wild text elements")
# TAG_CATALOG is a frozenset; the recall branch calls .update()
potential_tags = set(TAG_CATALOG) if potential_tags is None else potential_tags
search_expr = ".//blockquote|.//code|.//p|.//pre|.//q|.//quote|.//table|.//div[contains(@class, 'w3-code')]"
if options.focus == "recall":
potential_tags.update(["div", "lb"])
search_expr += "|.//div|.//lb|.//list"
# prune
search_tree = prune_unwanted_sections(tree, potential_tags, options)
# decide if links are preserved
if "ref" not in potential_tags:
strip_tags(search_tree, "a", "ref", "span")
else:
strip_tags(search_tree, "span")
subelems = search_tree.xpath(search_expr)
result_body.extend(
filter(
lambda x: x is not None, # type: ignore[arg-type]
(handle_textelem(e, potential_tags, options) for e in subelems),
)
)
return result_body
def prune_unwanted_sections(tree: HtmlElement, potential_tags: set[str], options: Extractor) -> HtmlElement:
"Rule-based deletion of targeted document sections"
favor_precision = options.focus == "precision"
# prune the rest
tree = prune_unwanted_nodes(tree, OVERALL_DISCARD_XPATH, with_backup=True)
# decide if images are preserved
if "graphic" not in potential_tags:
tree = prune_unwanted_nodes(tree, DISCARD_IMAGE_ELEMENTS)
# balance precision/recall
if options.focus != "recall":
tree = prune_unwanted_nodes(tree, TEASER_DISCARD_XPATH)
if favor_precision:
tree = prune_unwanted_nodes(tree, PRECISION_DISCARD_XPATH)
# remove elements by link density, several passes
for _ in range(2):
tree = delete_by_link_density(tree, "div", backtracking=True, favor_precision=favor_precision)
tree = delete_by_link_density(tree, "list", backtracking=False, favor_precision=favor_precision)
tree = delete_by_link_density(tree, "p", backtracking=False, favor_precision=favor_precision)
# tables
if "table" in potential_tags or favor_precision:
# tree = delete_by_link_density(tree, 'table', backtracking=False, favor_precision=favor_precision)
for elem in tree.iter("table"):
if link_density_test_tables(elem) is True:
delete_element(elem, keep_tail=False)
# also filter fw/head, table and quote elements?
if favor_precision:
# delete trailing titles
while len(tree) > 0 and (tree[-1].tag == "head"):
delete_element(tree[-1], keep_tail=False)
tree = delete_by_link_density(tree, "head", backtracking=False, favor_precision=True)
tree = delete_by_link_density(tree, "quote", backtracking=False, favor_precision=True)
return tree
def _extract(tree: HtmlElement, options: Extractor) -> tuple[_Element, str, set[str]]:
# init
potential_tags = set(TAG_CATALOG)
if options.tables is True:
potential_tags.update(["table", "td", "th", "tr"])
if options.images is True:
potential_tags.add("graphic")
if options.links is True:
potential_tags.add("ref")
result_body = Element("body")
# iterate
for expr in BODY_XPATH:
# select tree if the expression has been found
subtree = next((s for s in expr(tree) if s is not None), None)
if subtree is None:
continue
# prune the subtree
subtree = prune_unwanted_sections(subtree, potential_tags, options)
# skip if empty tree
if len(subtree) == 0:
continue
# no paragraphs containing text, or not enough
ptest = subtree.xpath("//p//text()")
factor = 1 if options.focus == "precision" else 3
if not ptest or len("".join(ptest)) < options.min_extracted_size * factor:
potential_tags.add("div")
# polish list of potential tags
if "ref" not in potential_tags:
strip_tags(subtree, "ref")
if "span" not in potential_tags:
strip_tags(subtree, "span")
LOGGER.debug(sorted(potential_tags))
# proper extraction
subelems = subtree.xpath(".//*")
# e.g. only lb-elems in a div
if {e.tag for e in subelems} == {"lb"}:
subelems = [subtree]
# extract content
result_body.extend([el for el in (handle_textelem(e, potential_tags, options) for e in subelems) if el is not None])
# remove trailing titles
while len(result_body) > 0 and (result_body[-1].tag in NOT_AT_THE_END):
delete_element(result_body[-1], keep_tail=False)
# exit once there is real content, not just a lone image
if sum(e.tag != "graphic" for e in result_body) > 1:
LOGGER.debug(trim(str(expr)))
break
temp_text = " ".join(result_body.itertext()).strip()
return result_body, temp_text, potential_tags
def extract_content(cleaned_tree: HtmlElement, options: Extractor) -> tuple[_Element, str, int]:
"""Find the main content of a page using a set of XPath expressions,
then extract relevant elements, strip them of unwanted subparts and
convert them"""
# backup
backup_tree = deepcopy(cleaned_tree)
result_body, temp_text, potential_tags = _extract(cleaned_tree, options)
# if len(result_body) == 0:
# result_body, temp_text, potential_tags = _extract(tree_backup, options)
# try parsing wild <p> elements if nothing found or text too short
# todo: test precision and recall settings here
if len(result_body) == 0 or len(temp_text) < options.min_extracted_size:
result_body = recover_wild_text(backup_tree, result_body, options, potential_tags)
temp_text = " ".join(result_body.itertext()).strip()
# drop substantial elements repeating the previous one (overlapping-candidate / recovery artifact);
# length-gated so short genuine repeats stay for the dedup (#778) and tree-size guards
previous = None
for el in list(result_body):
current = trim("".join(el.itertext()))
if current and current == previous and len(current) > DUPLICATE_ADJACENT_LIMIT:
delete_element(el, keep_tail=False)
else:
previous = current
# filter output
strip_elements(result_body, "done")
strip_tags(result_body, "div")
# return
return result_body, temp_text, len(temp_text)
def process_comments_node(elem: _Element, potential_tags: set[str], options: Extractor) -> _Element | None:
"""Process comment node and determine how to deal with its content"""
if elem.tag in potential_tags:
# print(elem.tag, elem.text_content())
processed_element = handle_textnode(elem, options, comments_fix=True)
# test length and remove
if processed_element is not None: # and processed_element.text not in COMMENTS_BLACKLIST:
processed_element.attrib.clear()
# if textfilter(elem) is True: # ^Pingback
# return None
return processed_element
return None
