mirror of
https://github.com/samuelclay/NewsBlur.git
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353 lines
12 KiB
Python
353 lines
12 KiB
Python
#!/usr/bin/env python
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#
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# Copyright 2009 Facebook
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Escaping/unescaping methods for HTML, JSON, URLs, and others.
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Also includes a few other miscellaneous string manipulation functions that
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have crept in over time.
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"""
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import html.entities
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import re
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import sys
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import urllib.parse
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from urllib.parse import parse_qs
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# json module is in the standard library as of python 2.6; fall back to
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# simplejson if present for older versions.
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try:
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import json
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assert hasattr(json, "loads") and hasattr(json, "dumps")
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_json_decode = json.loads
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_json_encode = json.dumps
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except Exception:
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try:
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import simplejson
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_json_decode = lambda s: simplejson.loads(_unicode(s))
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_json_encode = lambda v: simplejson.dumps(v)
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except ImportError:
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try:
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# For Google AppEngine
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from django.utils import simplejson
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_json_decode = lambda s: simplejson.loads(_unicode(s))
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_json_encode = lambda v: simplejson.dumps(v)
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except ImportError:
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def _json_decode(s):
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raise NotImplementedError(
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"A JSON parser is required, e.g., simplejson at "
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"http://pypi.python.org/pypi/simplejson/"
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)
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_json_encode = _json_decode
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_XHTML_ESCAPE_RE = re.compile('[&<>"]')
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_XHTML_ESCAPE_DICT = {"&": "&", "<": "<", ">": ">", '"': """}
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def xhtml_escape(value):
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"""Escapes a string so it is valid within XML or XHTML."""
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return _XHTML_ESCAPE_RE.sub(lambda match: _XHTML_ESCAPE_DICT[match.group(0)], to_basestring(value))
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def xhtml_unescape(value):
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"""Un-escapes an XML-escaped string."""
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return re.sub(r"&(#?)(\w+?);", _convert_entity, _unicode(value))
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def json_encode(value):
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"""JSON-encodes the given Python object."""
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# JSON permits but does not require forward slashes to be escaped.
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# This is useful when json data is emitted in a <script> tag
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# in HTML, as it prevents </script> tags from prematurely terminating
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# the javscript. Some json libraries do this escaping by default,
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# although python's standard library does not, so we do it here.
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# http://stackoverflow.com/questions/1580647/json-why-are-forward-slashes-escaped
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return _json_encode(recursive_unicode(value)).replace("</", "<\\/")
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def json_decode(value):
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"""Returns Python objects for the given JSON string."""
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return _json_decode(to_basestring(value))
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def squeeze(value):
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"""Replace all sequences of whitespace chars with a single space."""
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return re.sub(r"[\x00-\x20]+", " ", value).strip()
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def url_escape(value):
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"""Returns a valid URL-encoded version of the given value."""
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return urllib.parse.quote_plus(utf8(value))
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# python 3 changed things around enough that we need two separate
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# implementations of url_unescape. We also need our own implementation
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# of parse_qs since python 3's version insists on decoding everything.
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if sys.version_info[0] < 3:
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def url_unescape(value, encoding="utf-8"):
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"""Decodes the given value from a URL.
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The argument may be either a byte or unicode string.
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If encoding is None, the result will be a byte string. Otherwise,
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the result is a unicode string in the specified encoding.
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"""
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if encoding is None:
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return urllib.parse.unquote_plus(utf8(value))
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else:
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return str(urllib.parse.unquote_plus(utf8(value)), encoding)
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parse_qs_bytes = parse_qs
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else:
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def url_unescape(value, encoding="utf-8"):
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"""Decodes the given value from a URL.
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The argument may be either a byte or unicode string.
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If encoding is None, the result will be a byte string. Otherwise,
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the result is a unicode string in the specified encoding.
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"""
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if encoding is None:
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return urllib.parse.unquote_to_bytes(value)
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else:
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return urllib.parse.unquote_plus(to_basestring(value), encoding=encoding)
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def parse_qs_bytes(qs, keep_blank_values=False, strict_parsing=False):
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"""Parses a query string like urlparse.parse_qs, but returns the
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values as byte strings.
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Keys still become type str (interpreted as latin1 in python3!)
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because it's too painful to keep them as byte strings in
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python3 and in practice they're nearly always ascii anyway.
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"""
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# This is gross, but python3 doesn't give us another way.
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# Latin1 is the universal donor of character encodings.
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result = parse_qs(qs, keep_blank_values, strict_parsing, encoding="latin1", errors="strict")
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encoded = {}
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for k, v in result.items():
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encoded[k] = [i.encode("latin1") for i in v]
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return encoded
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_UTF8_TYPES = (bytes, type(None))
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def utf8(value):
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"""Converts a string argument to a byte string.
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If the argument is already a byte string or None, it is returned unchanged.
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Otherwise it must be a unicode string and is encoded as utf8.
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"""
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if isinstance(value, _UTF8_TYPES):
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return value
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assert isinstance(value, str)
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return value.encode("utf-8")
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_TO_UNICODE_TYPES = (str, type(None))
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def to_unicode(value):
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"""Converts a string argument to a unicode string.
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If the argument is already a unicode string or None, it is returned
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unchanged. Otherwise it must be a byte string and is decoded as utf8.
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"""
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if isinstance(value, _TO_UNICODE_TYPES):
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return value
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assert isinstance(value, bytes)
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return value.decode("utf-8")
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# to_unicode was previously named _unicode not because it was private,
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# but to avoid conflicts with the built-in unicode() function/type
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_unicode = to_unicode
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# When dealing with the standard library across python 2 and 3 it is
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# sometimes useful to have a direct conversion to the native string type
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if str is str:
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native_str = to_unicode
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else:
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native_str = utf8
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_BASESTRING_TYPES = (str, type(None))
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def to_basestring(value):
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"""Converts a string argument to a subclass of basestring.
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In python2, byte and unicode strings are mostly interchangeable,
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so functions that deal with a user-supplied argument in combination
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with ascii string constants can use either and should return the type
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the user supplied. In python3, the two types are not interchangeable,
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so this method is needed to convert byte strings to unicode.
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"""
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if isinstance(value, _BASESTRING_TYPES):
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return value
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assert isinstance(value, bytes)
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return value.decode("utf-8")
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def recursive_unicode(obj):
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"""Walks a simple data structure, converting byte strings to unicode.
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Supports lists, tuples, and dictionaries.
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"""
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if isinstance(obj, dict):
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return dict((recursive_unicode(k), recursive_unicode(v)) for (k, v) in obj.items())
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elif isinstance(obj, list):
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return list(recursive_unicode(i) for i in obj)
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elif isinstance(obj, tuple):
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return tuple(recursive_unicode(i) for i in obj)
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elif isinstance(obj, bytes):
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return to_unicode(obj)
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else:
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return obj
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# I originally used the regex from
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# http://daringfireball.net/2010/07/improved_regex_for_matching_urls
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# but it gets all exponential on certain patterns (such as too many trailing
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# dots), causing the regex matcher to never return.
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# This regex should avoid those problems.
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_URL_RE = re.compile(
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r"""\b((?:([\w-]+):(/{1,3})|www[.])(?:(?:(?:[^\s&()]|&|")*(?:[^!"#$%&'()*+,.:;<=>?@\[\]^`{|}~\s]))|(?:\((?:[^\s&()]|&|")*\)))+)"""
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)
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def linkify(
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text, shorten=False, extra_params="", require_protocol=False, permitted_protocols=["http", "https"]
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):
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"""Converts plain text into HTML with links.
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For example: ``linkify("Hello http://tornadoweb.org!")`` would return
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``Hello <a href="http://tornadoweb.org">http://tornadoweb.org</a>!``
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Parameters:
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shorten: Long urls will be shortened for display.
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extra_params: Extra text to include in the link tag, or a callable
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taking the link as an argument and returning the extra text
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e.g. ``linkify(text, extra_params='rel="nofollow" class="external"')``,
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or::
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def extra_params_cb(url):
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if url.startswith("http://example.com"):
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return 'class="internal"'
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else:
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return 'class="external" rel="nofollow"'
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linkify(text, extra_params=extra_params_cb)
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require_protocol: Only linkify urls which include a protocol. If this is
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False, urls such as www.facebook.com will also be linkified.
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permitted_protocols: List (or set) of protocols which should be linkified,
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e.g. linkify(text, permitted_protocols=["http", "ftp", "mailto"]).
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It is very unsafe to include protocols such as "javascript".
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"""
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if extra_params and not callable(extra_params):
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extra_params = " " + extra_params.strip()
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def make_link(m):
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url = m.group(1)
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proto = m.group(2)
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if require_protocol and not proto:
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return url # not protocol, no linkify
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if proto and proto not in permitted_protocols:
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return url # bad protocol, no linkify
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href = m.group(1)
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if not proto:
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href = "http://" + href # no proto specified, use http
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if callable(extra_params):
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params = " " + extra_params(href).strip()
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else:
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params = extra_params
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# clip long urls. max_len is just an approximation
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max_len = 30
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if shorten and len(url) > max_len:
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before_clip = url
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if proto:
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proto_len = len(proto) + 1 + len(m.group(3) or "") # +1 for :
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else:
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proto_len = 0
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parts = url[proto_len:].split("/")
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if len(parts) > 1:
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# Grab the whole host part plus the first bit of the path
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# The path is usually not that interesting once shortened
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# (no more slug, etc), so it really just provides a little
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# extra indication of shortening.
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url = url[:proto_len] + parts[0] + "/" + parts[1][:8].split("?")[0].split(".")[0]
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if len(url) > max_len * 1.5: # still too long
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url = url[:max_len]
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if url != before_clip:
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amp = url.rfind("&")
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# avoid splitting html char entities
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if amp > max_len - 5:
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url = url[:amp]
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url += "..."
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if len(url) >= len(before_clip):
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url = before_clip
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else:
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# full url is visible on mouse-over (for those who don't
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# have a status bar, such as Safari by default)
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params += ' title="%s"' % href
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return '<a href="%s"%s>%s</a>' % (href, params, url)
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# First HTML-escape so that our strings are all safe.
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# The regex is modified to avoid character entites other than & so
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# that we won't pick up ", etc.
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text = _unicode(xhtml_escape(text))
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return _URL_RE.sub(make_link, text)
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def _convert_entity(m):
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if m.group(1) == "#":
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try:
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return chr(int(m.group(2)))
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except ValueError:
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return "&#%s;" % m.group(2)
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try:
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return _HTML_UNICODE_MAP[m.group(2)]
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except KeyError:
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return "&%s;" % m.group(2)
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def _build_unicode_map():
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unicode_map = {}
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for name, value in html.entities.name2codepoint.items():
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unicode_map[name] = chr(value)
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return unicode_map
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_HTML_UNICODE_MAP = _build_unicode_map()
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