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338 lines
11 KiB
338 lines
11 KiB
# -*- coding: utf-8 -*-
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"""
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Functions for dealing with markup text
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"""
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import warnings
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import re
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import six
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from six import moves
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from w3lib.util import to_bytes, to_unicode
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from w3lib.url import safe_url_string
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_ent_re = re.compile(r'&((?P<named>[a-z\d]+)|#(?P<dec>\d+)|#x(?P<hex>[a-f\d]+))(?P<semicolon>;?)', re.IGNORECASE)
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_tag_re = re.compile(r'<[a-zA-Z\/!].*?>', re.DOTALL)
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_baseurl_re = re.compile(six.u(r'<base\s[^>]*href\s*=\s*[\"\']\s*([^\"\'\s]+)\s*[\"\']'), re.I)
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_meta_refresh_re = re.compile(six.u(r'<meta\s[^>]*http-equiv[^>]*refresh[^>]*content\s*=\s*(?P<quote>["\'])(?P<int>(\d*\.)?\d+)\s*;\s*url=\s*(?P<url>.*?)(?P=quote)'), re.DOTALL | re.IGNORECASE)
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_cdata_re = re.compile(r'((?P<cdata_s><!\[CDATA\[)(?P<cdata_d>.*?)(?P<cdata_e>\]\]>))', re.DOTALL)
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HTML5_WHITESPACE = ' \t\n\r\x0c'
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def remove_entities(text, keep=(), remove_illegal=True, encoding='utf-8'):
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r"""
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.. warning::
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This function is deprecated and will be removed in future.
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Please use :func:`replace_entities` instead.
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"""
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warnings.warn(
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"`w3lib.html.remove_entities` function is deprecated and "
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"will be removed in future releases. Please use "
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"`w3lib.html.replace_entities` instead.",
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DeprecationWarning
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)
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return replace_entities(text, keep, remove_illegal, encoding)
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def replace_entities(text, keep=(), remove_illegal=True, encoding='utf-8'):
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u"""Remove entities from the given `text` by converting them to their
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corresponding unicode character.
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`text` can be a unicode string or a byte string encoded in the given
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`encoding` (which defaults to 'utf-8').
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If `keep` is passed (with a list of entity names) those entities will
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be kept (they won't be removed).
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It supports both numeric entities (``&#nnnn;`` and ``&#hhhh;``)
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and named entities (such as `` `` or ``>``).
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If `remove_illegal` is ``True``, entities that can't be converted are removed.
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If `remove_illegal` is ``False``, entities that can't be converted are kept "as
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is". For more information see the tests.
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Always returns a unicode string (with the entities removed).
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>>> import w3lib.html
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>>> w3lib.html.replace_entities(b'Price: £100')
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u'Price: \\xa3100'
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>>> print(w3lib.html.replace_entities(b'Price: £100'))
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Price: £100
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>>>
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"""
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def convert_entity(m):
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groups = m.groupdict()
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if groups.get('dec'):
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number = int(groups['dec'], 10)
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elif groups.get('hex'):
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number = int(groups['hex'], 16)
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elif groups.get('named'):
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entity_name = groups['named']
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if entity_name.lower() in keep:
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return m.group(0)
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else:
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number = (moves.html_entities.name2codepoint.get(entity_name) or
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moves.html_entities.name2codepoint.get(entity_name.lower()))
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if number is not None:
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# Numeric character references in the 80-9F range are typically
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# interpreted by browsers as representing the characters mapped
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# to bytes 80-9F in the Windows-1252 encoding. For more info
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# see: http://en.wikipedia.org/wiki/Character_encodings_in_HTML
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try:
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if 0x80 <= number <= 0x9f:
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return six.int2byte(number).decode('cp1252')
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else:
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return six.unichr(number)
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except ValueError:
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pass
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return u'' if remove_illegal and groups.get('semicolon') else m.group(0)
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return _ent_re.sub(convert_entity, to_unicode(text, encoding))
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def has_entities(text, encoding=None):
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return bool(_ent_re.search(to_unicode(text, encoding)))
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def replace_tags(text, token='', encoding=None):
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"""Replace all markup tags found in the given `text` by the given token.
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By default `token` is an empty string so it just removes all tags.
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`text` can be a unicode string or a regular string encoded as `encoding`
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(or ``'utf-8'`` if `encoding` is not given.)
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Always returns a unicode string.
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Examples:
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>>> import w3lib.html
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>>> w3lib.html.replace_tags(u'This text contains <a>some tag</a>')
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u'This text contains some tag'
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>>> w3lib.html.replace_tags('<p>Je ne parle pas <b>fran\\xe7ais</b></p>', ' -- ', 'latin-1')
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u' -- Je ne parle pas -- fran\\xe7ais -- -- '
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>>>
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"""
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return _tag_re.sub(token, to_unicode(text, encoding))
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_REMOVECOMMENTS_RE = re.compile(u'<!--.*?-->', re.DOTALL)
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def remove_comments(text, encoding=None):
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""" Remove HTML Comments.
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>>> import w3lib.html
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>>> w3lib.html.remove_comments(b"test <!--textcoment--> whatever")
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u'test whatever'
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>>>
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"""
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text = to_unicode(text, encoding)
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return _REMOVECOMMENTS_RE.sub(u'', text)
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def remove_tags(text, which_ones=(), keep=(), encoding=None):
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""" Remove HTML Tags only.
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`which_ones` and `keep` are both tuples, there are four cases:
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============== ============= ==========================================
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``which_ones`` ``keep`` what it does
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============== ============= ==========================================
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**not empty** empty remove all tags in ``which_ones``
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empty **not empty** remove all tags except the ones in ``keep``
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empty empty remove all tags
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**not empty** **not empty** not allowed
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============== ============= ==========================================
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Remove all tags:
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>>> import w3lib.html
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>>> doc = '<div><p><b>This is a link:</b> <a href="http://www.example.com">example</a></p></div>'
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>>> w3lib.html.remove_tags(doc)
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u'This is a link: example'
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>>>
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Keep only some tags:
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>>> w3lib.html.remove_tags(doc, keep=('div',))
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u'<div>This is a link: example</div>'
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>>>
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Remove only specific tags:
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>>> w3lib.html.remove_tags(doc, which_ones=('a','b'))
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u'<div><p>This is a link: example</p></div>'
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>>>
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You can't remove some and keep some:
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>>> w3lib.html.remove_tags(doc, which_ones=('a',), keep=('p',))
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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File "/usr/local/lib/python2.7/dist-packages/w3lib/html.py", line 101, in remove_tags
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assert not (which_ones and keep), 'which_ones and keep can not be given at the same time'
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AssertionError: which_ones and keep can not be given at the same time
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>>>
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"""
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assert not (which_ones and keep), 'which_ones and keep can not be given at the same time'
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which_ones = {tag.lower() for tag in which_ones}
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keep = {tag.lower() for tag in keep}
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def will_remove(tag):
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tag = tag.lower()
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if which_ones:
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return tag in which_ones
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else:
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return tag not in keep
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def remove_tag(m):
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tag = m.group(1)
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return u'' if will_remove(tag) else m.group(0)
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regex = '</?([^ >/]+).*?>'
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retags = re.compile(regex, re.DOTALL | re.IGNORECASE)
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return retags.sub(remove_tag, to_unicode(text, encoding))
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def remove_tags_with_content(text, which_ones=(), encoding=None):
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"""Remove tags and their content.
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`which_ones` is a tuple of which tags to remove including their content.
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If is empty, returns the string unmodified.
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>>> import w3lib.html
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>>> doc = '<div><p><b>This is a link:</b> <a href="http://www.example.com">example</a></p></div>'
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>>> w3lib.html.remove_tags_with_content(doc, which_ones=('b',))
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u'<div><p> <a href="http://www.example.com">example</a></p></div>'
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>>>
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"""
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text = to_unicode(text, encoding)
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if which_ones:
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tags = '|'.join([r'<%s.*?</%s>|<%s\s*/>' % (tag, tag, tag) for tag in which_ones])
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retags = re.compile(tags, re.DOTALL | re.IGNORECASE)
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text = retags.sub(u'', text)
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return text
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def replace_escape_chars(text, which_ones=('\n', '\t', '\r'), replace_by=u'', \
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encoding=None):
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"""Remove escape characters.
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`which_ones` is a tuple of which escape characters we want to remove.
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By default removes ``\\n``, ``\\t``, ``\\r``.
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`replace_by` is the string to replace the escape characters by.
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It defaults to ``''``, meaning the escape characters are removed.
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"""
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text = to_unicode(text, encoding)
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for ec in which_ones:
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text = text.replace(ec, to_unicode(replace_by, encoding))
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return text
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def unquote_markup(text, keep=(), remove_illegal=True, encoding=None):
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"""
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This function receives markup as a text (always a unicode string or
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a UTF-8 encoded string) and does the following:
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1. removes entities (except the ones in `keep`) from any part of it
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that is not inside a CDATA
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2. searches for CDATAs and extracts their text (if any) without modifying it.
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3. removes the found CDATAs
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"""
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def _get_fragments(txt, pattern):
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offset = 0
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for match in pattern.finditer(txt):
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match_s, match_e = match.span(1)
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yield txt[offset:match_s]
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yield match
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offset = match_e
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yield txt[offset:]
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text = to_unicode(text, encoding)
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ret_text = u''
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for fragment in _get_fragments(text, _cdata_re):
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if isinstance(fragment, six.string_types):
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# it's not a CDATA (so we try to remove its entities)
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ret_text += replace_entities(fragment, keep=keep, remove_illegal=remove_illegal)
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else:
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# it's a CDATA (so we just extract its content)
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ret_text += fragment.group('cdata_d')
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return ret_text
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def get_base_url(text, baseurl='', encoding='utf-8'):
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"""Return the base url if declared in the given HTML `text`,
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relative to the given base url.
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If no base url is found, the given `baseurl` is returned.
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"""
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text = to_unicode(text, encoding)
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m = _baseurl_re.search(text)
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if m:
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return moves.urllib.parse.urljoin(
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safe_url_string(baseurl),
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safe_url_string(m.group(1), encoding=encoding)
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)
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else:
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return safe_url_string(baseurl)
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def get_meta_refresh(text, baseurl='', encoding='utf-8', ignore_tags=('script', 'noscript')):
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"""Return the http-equiv parameter of the HTML meta element from the given
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HTML text and return a tuple ``(interval, url)`` where interval is an integer
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containing the delay in seconds (or zero if not present) and url is a
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string with the absolute url to redirect.
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If no meta redirect is found, ``(None, None)`` is returned.
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"""
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if six.PY2:
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baseurl = to_bytes(baseurl, encoding)
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try:
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text = to_unicode(text, encoding)
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except UnicodeDecodeError:
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print(text)
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raise
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text = remove_tags_with_content(text, ignore_tags)
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text = remove_comments(replace_entities(text))
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m = _meta_refresh_re.search(text)
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if m:
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interval = float(m.group('int'))
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url = safe_url_string(m.group('url').strip(' "\''), encoding)
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url = moves.urllib.parse.urljoin(baseurl, url)
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return interval, url
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else:
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return None, None
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def strip_html5_whitespace(text):
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r"""
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Strip all leading and trailing space characters (as defined in
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https://www.w3.org/TR/html5/infrastructure.html#space-character).
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Such stripping is useful e.g. for processing HTML element attributes which
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contain URLs, like ``href``, ``src`` or form ``action`` - HTML5 standard
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defines them as "valid URL potentially surrounded by spaces"
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or "valid non-empty URL potentially surrounded by spaces".
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>>> strip_html5_whitespace(' hello\n')
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'hello'
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"""
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return text.strip(HTML5_WHITESPACE)
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