422 lines
14 KiB
Python
422 lines
14 KiB
Python
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"""HTML utilities suitable for global use."""
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import html
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import json
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import re
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from html.parser import HTMLParser
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from urllib.parse import parse_qsl, quote, unquote, urlencode, urlsplit, urlunsplit
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from django.utils.encoding import punycode
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from django.utils.functional import Promise, keep_lazy, keep_lazy_text
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from django.utils.http import RFC3986_GENDELIMS, RFC3986_SUBDELIMS
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from django.utils.regex_helper import _lazy_re_compile
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from django.utils.safestring import SafeData, SafeString, mark_safe
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from django.utils.text import normalize_newlines
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@keep_lazy(SafeString)
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def escape(text):
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"""
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Return the given text with ampersands, quotes and angle brackets encoded
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for use in HTML.
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Always escape input, even if it's already escaped and marked as such.
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This may result in double-escaping. If this is a concern, use
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conditional_escape() instead.
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"""
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return SafeString(html.escape(str(text)))
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_js_escapes = {
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ord("\\"): "\\u005C",
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ord("'"): "\\u0027",
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ord('"'): "\\u0022",
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ord(">"): "\\u003E",
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ord("<"): "\\u003C",
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ord("&"): "\\u0026",
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ord("="): "\\u003D",
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ord("-"): "\\u002D",
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ord(";"): "\\u003B",
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ord("`"): "\\u0060",
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ord("\u2028"): "\\u2028",
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ord("\u2029"): "\\u2029",
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}
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# Escape every ASCII character with a value less than 32.
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_js_escapes.update((ord("%c" % z), "\\u%04X" % z) for z in range(32))
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@keep_lazy(SafeString)
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def escapejs(value):
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"""Hex encode characters for use in JavaScript strings."""
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return mark_safe(str(value).translate(_js_escapes))
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_json_script_escapes = {
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ord(">"): "\\u003E",
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ord("<"): "\\u003C",
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ord("&"): "\\u0026",
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}
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def json_script(value, element_id=None):
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"""
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Escape all the HTML/XML special characters with their unicode escapes, so
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value is safe to be output anywhere except for inside a tag attribute. Wrap
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the escaped JSON in a script tag.
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"""
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from django.core.serializers.json import DjangoJSONEncoder
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json_str = json.dumps(value, cls=DjangoJSONEncoder).translate(_json_script_escapes)
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if element_id:
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template = '<script id="{}" type="application/json">{}</script>'
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args = (element_id, mark_safe(json_str))
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else:
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template = '<script type="application/json">{}</script>'
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args = (mark_safe(json_str),)
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return format_html(template, *args)
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def conditional_escape(text):
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"""
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Similar to escape(), except that it doesn't operate on pre-escaped strings.
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This function relies on the __html__ convention used both by Django's
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SafeData class and by third-party libraries like markupsafe.
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"""
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if isinstance(text, Promise):
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text = str(text)
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if hasattr(text, "__html__"):
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return text.__html__()
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else:
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return escape(text)
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def format_html(format_string, *args, **kwargs):
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"""
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Similar to str.format, but pass all arguments through conditional_escape(),
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and call mark_safe() on the result. This function should be used instead
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of str.format or % interpolation to build up small HTML fragments.
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"""
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args_safe = map(conditional_escape, args)
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kwargs_safe = {k: conditional_escape(v) for (k, v) in kwargs.items()}
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return mark_safe(format_string.format(*args_safe, **kwargs_safe))
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def format_html_join(sep, format_string, args_generator):
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"""
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A wrapper of format_html, for the common case of a group of arguments that
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need to be formatted using the same format string, and then joined using
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'sep'. 'sep' is also passed through conditional_escape.
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'args_generator' should be an iterator that returns the sequence of 'args'
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that will be passed to format_html.
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Example:
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format_html_join('\n', "<li>{} {}</li>", ((u.first_name, u.last_name)
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for u in users))
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"""
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return mark_safe(
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conditional_escape(sep).join(
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format_html(format_string, *args) for args in args_generator
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)
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)
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@keep_lazy_text
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def linebreaks(value, autoescape=False):
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"""Convert newlines into <p> and <br>s."""
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value = normalize_newlines(value)
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paras = re.split("\n{2,}", str(value))
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if autoescape:
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paras = ["<p>%s</p>" % escape(p).replace("\n", "<br>") for p in paras]
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else:
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paras = ["<p>%s</p>" % p.replace("\n", "<br>") for p in paras]
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return "\n\n".join(paras)
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class MLStripper(HTMLParser):
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def __init__(self):
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super().__init__(convert_charrefs=False)
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self.reset()
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self.fed = []
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def handle_data(self, d):
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self.fed.append(d)
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def handle_entityref(self, name):
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self.fed.append("&%s;" % name)
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def handle_charref(self, name):
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self.fed.append("&#%s;" % name)
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def get_data(self):
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return "".join(self.fed)
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def _strip_once(value):
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"""
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Internal tag stripping utility used by strip_tags.
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"""
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s = MLStripper()
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s.feed(value)
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s.close()
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return s.get_data()
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@keep_lazy_text
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def strip_tags(value):
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"""Return the given HTML with all tags stripped."""
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# Note: in typical case this loop executes _strip_once once. Loop condition
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# is redundant, but helps to reduce number of executions of _strip_once.
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value = str(value)
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while "<" in value and ">" in value:
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new_value = _strip_once(value)
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if value.count("<") == new_value.count("<"):
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# _strip_once wasn't able to detect more tags.
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break
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value = new_value
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return value
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@keep_lazy_text
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def strip_spaces_between_tags(value):
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"""Return the given HTML with spaces between tags removed."""
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return re.sub(r">\s+<", "><", str(value))
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def smart_urlquote(url):
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"""Quote a URL if it isn't already quoted."""
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def unquote_quote(segment):
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segment = unquote(segment)
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# Tilde is part of RFC3986 Unreserved Characters
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# https://tools.ietf.org/html/rfc3986#section-2.3
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# See also https://bugs.python.org/issue16285
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return quote(segment, safe=RFC3986_SUBDELIMS + RFC3986_GENDELIMS + "~")
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# Handle IDN before quoting.
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try:
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scheme, netloc, path, query, fragment = urlsplit(url)
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except ValueError:
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# invalid IPv6 URL (normally square brackets in hostname part).
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return unquote_quote(url)
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try:
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netloc = punycode(netloc) # IDN -> ACE
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except UnicodeError: # invalid domain part
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return unquote_quote(url)
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if query:
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# Separately unquoting key/value, so as to not mix querystring separators
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# included in query values. See #22267.
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query_parts = [
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(unquote(q[0]), unquote(q[1]))
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for q in parse_qsl(query, keep_blank_values=True)
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]
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# urlencode will take care of quoting
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query = urlencode(query_parts)
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path = unquote_quote(path)
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fragment = unquote_quote(fragment)
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return urlunsplit((scheme, netloc, path, query, fragment))
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class Urlizer:
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"""
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Convert any URLs in text into clickable links.
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Work on http://, https://, www. links, and also on links ending in one of
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the original seven gTLDs (.com, .edu, .gov, .int, .mil, .net, and .org).
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Links can have trailing punctuation (periods, commas, close-parens) and
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leading punctuation (opening parens) and it'll still do the right thing.
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"""
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trailing_punctuation_chars = ".,:;!"
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wrapping_punctuation = [("(", ")"), ("[", "]")]
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simple_url_re = _lazy_re_compile(r"^https?://\[?\w", re.IGNORECASE)
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simple_url_2_re = _lazy_re_compile(
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r"^www\.|^(?!http)\w[^@]+\.(com|edu|gov|int|mil|net|org)($|/.*)$", re.IGNORECASE
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)
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word_split_re = _lazy_re_compile(r"""([\s<>"']+)""")
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mailto_template = "mailto:{local}@{domain}"
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url_template = '<a href="{href}"{attrs}>{url}</a>'
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def __call__(self, text, trim_url_limit=None, nofollow=False, autoescape=False):
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"""
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If trim_url_limit is not None, truncate the URLs in the link text
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longer than this limit to trim_url_limit - 1 characters and append an
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ellipsis.
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If nofollow is True, give the links a rel="nofollow" attribute.
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If autoescape is True, autoescape the link text and URLs.
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"""
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safe_input = isinstance(text, SafeData)
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words = self.word_split_re.split(str(text))
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return "".join(
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[
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self.handle_word(
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word,
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safe_input=safe_input,
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trim_url_limit=trim_url_limit,
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nofollow=nofollow,
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autoescape=autoescape,
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)
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for word in words
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]
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)
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def handle_word(
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self,
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word,
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*,
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safe_input,
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trim_url_limit=None,
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nofollow=False,
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autoescape=False,
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):
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if "." in word or "@" in word or ":" in word:
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# lead: Punctuation trimmed from the beginning of the word.
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# middle: State of the word.
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# trail: Punctuation trimmed from the end of the word.
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lead, middle, trail = self.trim_punctuation(word)
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# Make URL we want to point to.
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url = None
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nofollow_attr = ' rel="nofollow"' if nofollow else ""
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if self.simple_url_re.match(middle):
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url = smart_urlquote(html.unescape(middle))
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elif self.simple_url_2_re.match(middle):
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url = smart_urlquote("http://%s" % html.unescape(middle))
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elif ":" not in middle and self.is_email_simple(middle):
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local, domain = middle.rsplit("@", 1)
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try:
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domain = punycode(domain)
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except UnicodeError:
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return word
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url = self.mailto_template.format(local=local, domain=domain)
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nofollow_attr = ""
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# Make link.
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if url:
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trimmed = self.trim_url(middle, limit=trim_url_limit)
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if autoescape and not safe_input:
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lead, trail = escape(lead), escape(trail)
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trimmed = escape(trimmed)
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middle = self.url_template.format(
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href=escape(url),
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attrs=nofollow_attr,
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url=trimmed,
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)
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return mark_safe(f"{lead}{middle}{trail}")
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else:
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if safe_input:
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return mark_safe(word)
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elif autoescape:
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return escape(word)
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elif safe_input:
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return mark_safe(word)
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elif autoescape:
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return escape(word)
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return word
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def trim_url(self, x, *, limit):
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if limit is None or len(x) <= limit:
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return x
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return "%s…" % x[: max(0, limit - 1)]
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def trim_punctuation(self, word):
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"""
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Trim trailing and wrapping punctuation from `word`. Return the items of
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the new state.
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"""
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lead, middle, trail = "", word, ""
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# Continue trimming until middle remains unchanged.
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trimmed_something = True
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while trimmed_something:
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trimmed_something = False
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# Trim wrapping punctuation.
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for opening, closing in self.wrapping_punctuation:
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if middle.startswith(opening):
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middle = middle[len(opening) :]
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lead += opening
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trimmed_something = True
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# Keep parentheses at the end only if they're balanced.
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if (
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middle.endswith(closing)
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and middle.count(closing) == middle.count(opening) + 1
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):
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middle = middle[: -len(closing)]
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trail = closing + trail
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trimmed_something = True
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# Trim trailing punctuation (after trimming wrapping punctuation,
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# as encoded entities contain ';'). Unescape entities to avoid
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# breaking them by removing ';'.
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middle_unescaped = html.unescape(middle)
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stripped = middle_unescaped.rstrip(self.trailing_punctuation_chars)
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if middle_unescaped != stripped:
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punctuation_count = len(middle_unescaped) - len(stripped)
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trail = middle[-punctuation_count:] + trail
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middle = middle[:-punctuation_count]
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trimmed_something = True
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return lead, middle, trail
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@staticmethod
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def is_email_simple(value):
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"""Return True if value looks like an email address."""
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# An @ must be in the middle of the value.
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|
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if "@" not in value or value.startswith("@") or value.endswith("@"):
|
||
|
|
return False
|
||
|
|
try:
|
||
|
|
p1, p2 = value.split("@")
|
||
|
|
except ValueError:
|
||
|
|
# value contains more than one @.
|
||
|
|
return False
|
||
|
|
# Dot must be in p2 (e.g. example.com)
|
||
|
|
if "." not in p2 or p2.startswith("."):
|
||
|
|
return False
|
||
|
|
return True
|
||
|
|
|
||
|
|
|
||
|
|
urlizer = Urlizer()
|
||
|
|
|
||
|
|
|
||
|
|
@keep_lazy_text
|
||
|
|
def urlize(text, trim_url_limit=None, nofollow=False, autoescape=False):
|
||
|
|
return urlizer(
|
||
|
|
text, trim_url_limit=trim_url_limit, nofollow=nofollow, autoescape=autoescape
|
||
|
|
)
|
||
|
|
|
||
|
|
|
||
|
|
def avoid_wrapping(value):
|
||
|
|
"""
|
||
|
|
Avoid text wrapping in the middle of a phrase by adding non-breaking
|
||
|
|
spaces where there previously were normal spaces.
|
||
|
|
"""
|
||
|
|
return value.replace(" ", "\xa0")
|
||
|
|
|
||
|
|
|
||
|
|
def html_safe(klass):
|
||
|
|
"""
|
||
|
|
A decorator that defines the __html__ method. This helps non-Django
|
||
|
|
templates to detect classes whose __str__ methods return SafeString.
|
||
|
|
"""
|
||
|
|
if "__html__" in klass.__dict__:
|
||
|
|
raise ValueError(
|
||
|
|
"can't apply @html_safe to %s because it defines "
|
||
|
|
"__html__()." % klass.__name__
|
||
|
|
)
|
||
|
|
if "__str__" not in klass.__dict__:
|
||
|
|
raise ValueError(
|
||
|
|
"can't apply @html_safe to %s because it doesn't "
|
||
|
|
"define __str__()." % klass.__name__
|
||
|
|
)
|
||
|
|
klass_str = klass.__str__
|
||
|
|
klass.__str__ = lambda self: mark_safe(klass_str(self))
|
||
|
|
klass.__html__ = lambda self: str(self)
|
||
|
|
return klass
|