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bazarr/libs/markdown/inlinepatterns.py

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"""
INLINE PATTERNS
=============================================================================
Inline patterns such as *emphasis* are handled by means of auxiliary
objects, one per pattern. Pattern objects must be instances of classes
that extend markdown.Pattern. Each pattern object uses a single regular
expression and needs support the following methods:
pattern.getCompiledRegExp() # returns a regular expression
pattern.handleMatch(m) # takes a match object and returns
# an ElementTree element or just plain text
All of python markdown's built-in patterns subclass from Pattern,
but you can add additional patterns that don't.
Also note that all the regular expressions used by inline must
capture the whole block. For this reason, they all start with
'^(.*)' and end with '(.*)!'. In case with built-in expression
Pattern takes care of adding the "^(.*)" and "(.*)!".
Finally, the order in which regular expressions are applied is very
important - e.g. if we first replace http://.../ links with <a> tags
and _then_ try to replace inline html, we would end up with a mess.
So, we apply the expressions in the following order:
* escape and backticks have to go before everything else, so
that we can preempt any markdown patterns by escaping them.
* then we handle auto-links (must be done before inline html)
* then we handle inline HTML. At this point we will simply
replace all inline HTML strings with a placeholder and add
the actual HTML to a hash.
* then inline images (must be done before links)
* then bracketed links, first regular then reference-style
* finally we apply strong and emphasis
"""
from __future__ import absolute_import
from __future__ import unicode_literals
from . import util
from . import odict
import re
try: # pragma: no cover
from urllib.parse import urlparse, urlunparse
except ImportError: # pragma: no cover
from urlparse import urlparse, urlunparse
try: # pragma: no cover
from html import entities
except ImportError: # pragma: no cover
import htmlentitydefs as entities
def build_inlinepatterns(md_instance, **kwargs):
""" Build the default set of inline patterns for Markdown. """
inlinePatterns = odict.OrderedDict()
inlinePatterns["backtick"] = BacktickPattern(BACKTICK_RE)
inlinePatterns["escape"] = EscapePattern(ESCAPE_RE, md_instance)
inlinePatterns["reference"] = ReferencePattern(REFERENCE_RE, md_instance)
inlinePatterns["link"] = LinkPattern(LINK_RE, md_instance)
inlinePatterns["image_link"] = ImagePattern(IMAGE_LINK_RE, md_instance)
inlinePatterns["image_reference"] = ImageReferencePattern(
IMAGE_REFERENCE_RE, md_instance
)
inlinePatterns["short_reference"] = ReferencePattern(
SHORT_REF_RE, md_instance
)
inlinePatterns["autolink"] = AutolinkPattern(AUTOLINK_RE, md_instance)
inlinePatterns["automail"] = AutomailPattern(AUTOMAIL_RE, md_instance)
inlinePatterns["linebreak"] = SubstituteTagPattern(LINE_BREAK_RE, 'br')
if md_instance.safeMode != 'escape':
inlinePatterns["html"] = HtmlPattern(HTML_RE, md_instance)
inlinePatterns["entity"] = HtmlPattern(ENTITY_RE, md_instance)
inlinePatterns["not_strong"] = SimpleTextPattern(NOT_STRONG_RE)
inlinePatterns["em_strong"] = DoubleTagPattern(EM_STRONG_RE, 'strong,em')
inlinePatterns["strong_em"] = DoubleTagPattern(STRONG_EM_RE, 'em,strong')
inlinePatterns["strong"] = SimpleTagPattern(STRONG_RE, 'strong')
inlinePatterns["emphasis"] = SimpleTagPattern(EMPHASIS_RE, 'em')
if md_instance.smart_emphasis:
inlinePatterns["emphasis2"] = SimpleTagPattern(SMART_EMPHASIS_RE, 'em')
else:
inlinePatterns["emphasis2"] = SimpleTagPattern(EMPHASIS_2_RE, 'em')
return inlinePatterns
"""
The actual regular expressions for patterns
-----------------------------------------------------------------------------
"""
NOBRACKET = r'[^\]\[]*'
BRK = (
r'\[(' +
(NOBRACKET + r'(\[')*6 +
(NOBRACKET + r'\])*')*6 +
NOBRACKET + r')\]'
)
NOIMG = r'(?<!\!)'
# `e=f()` or ``e=f("`")``
BACKTICK_RE = r'(?:(?<!\\)((?:\\{2})+)(?=`+)|(?<!\\)(`+)(.+?)(?<!`)\3(?!`))'
# \<
ESCAPE_RE = r'\\(.)'
# *emphasis*
EMPHASIS_RE = r'(\*)([^\*]+)\2'
# **strong**
STRONG_RE = r'(\*{2}|_{2})(.+?)\2'
# ***strongem*** or ***em*strong**
EM_STRONG_RE = r'(\*|_)\2{2}(.+?)\2(.*?)\2{2}'
# ***strong**em*
STRONG_EM_RE = r'(\*|_)\2{2}(.+?)\2{2}(.*?)\2'
# _smart_emphasis_
SMART_EMPHASIS_RE = r'(?<!\w)(_)(?!_)(.+?)(?<!_)\2(?!\w)'
# _emphasis_
EMPHASIS_2_RE = r'(_)(.+?)\2'
# [text](url) or [text](<url>) or [text](url "title")
LINK_RE = NOIMG + BRK + \
r'''\(\s*(<.*?>|((?:(?:\(.*?\))|[^\(\)]))*?)\s*((['"])(.*?)\12\s*)?\)'''
# ![alttxt](http://x.com/) or ![alttxt](<http://x.com/>)
IMAGE_LINK_RE = r'\!' + BRK + r'\s*\(\s*(<.*?>|([^"\)\s]+\s*"[^"]*"|[^\)\s]*))\s*\)'
# [Google][3]
REFERENCE_RE = NOIMG + BRK + r'\s?\[([^\]]*)\]'
# [Google]
SHORT_REF_RE = NOIMG + r'\[([^\]]+)\]'
# ![alt text][2]
IMAGE_REFERENCE_RE = r'\!' + BRK + r'\s?\[([^\]]*)\]'
# stand-alone * or _
NOT_STRONG_RE = r'((^| )(\*|_)( |$))'
# <http://www.123.com>
AUTOLINK_RE = r'<((?:[Ff]|[Hh][Tt])[Tt][Pp][Ss]?://[^>]*)>'
# <me@example.com>
AUTOMAIL_RE = r'<([^> \!]*@[^> ]*)>'
# <...>
HTML_RE = r'(\<([a-zA-Z/][^\>]*?|\!--.*?--)\>)'
# &amp;
ENTITY_RE = r'(&[\#a-zA-Z0-9]*;)'
# two spaces at end of line
LINE_BREAK_RE = r' \n'
def dequote(string):
"""Remove quotes from around a string."""
if ((string.startswith('"') and string.endswith('"')) or
(string.startswith("'") and string.endswith("'"))):
return string[1:-1]
else:
return string
ATTR_RE = re.compile(r"\{@([^\}]*)=([^\}]*)}") # {@id=123}
def handleAttributes(text, parent):
"""Set values of an element based on attribute definitions ({@id=123})."""
def attributeCallback(match):
parent.set(match.group(1), match.group(2).replace('\n', ' '))
return ATTR_RE.sub(attributeCallback, text)
"""
The pattern classes
-----------------------------------------------------------------------------
"""
class Pattern(object):
"""Base class that inline patterns subclass. """
ANCESTOR_EXCLUDES = tuple()
def __init__(self, pattern, markdown_instance=None):
"""
Create an instant of an inline pattern.
Keyword arguments:
* pattern: A regular expression that matches a pattern
"""
self.pattern = pattern
self.compiled_re = re.compile(r"^(.*?)%s(.*)$" % pattern,
re.DOTALL | re.UNICODE)
# Api for Markdown to pass safe_mode into instance
self.safe_mode = False
if markdown_instance:
self.markdown = markdown_instance
def getCompiledRegExp(self):
""" Return a compiled regular expression. """
return self.compiled_re
def handleMatch(self, m):
"""Return a ElementTree element from the given match.
Subclasses should override this method.
Keyword arguments:
* m: A re match object containing a match of the pattern.
"""
pass # pragma: no cover
def type(self):
""" Return class name, to define pattern type """
return self.__class__.__name__
def unescape(self, text):
""" Return unescaped text given text with an inline placeholder. """
try:
stash = self.markdown.treeprocessors['inline'].stashed_nodes
except KeyError: # pragma: no cover
return text
def itertext(el): # pragma: no cover
' Reimplement Element.itertext for older python versions '
tag = el.tag
if not isinstance(tag, util.string_type) and tag is not None:
return
if el.text:
yield el.text
for e in el:
for s in itertext(e):
yield s
if e.tail:
yield e.tail
def get_stash(m):
id = m.group(1)
if id in stash:
value = stash.get(id)
if isinstance(value, util.string_type):
return value
else:
# An etree Element - return text content only
return ''.join(itertext(value))
return util.INLINE_PLACEHOLDER_RE.sub(get_stash, text)
class SimpleTextPattern(Pattern):
""" Return a simple text of group(2) of a Pattern. """
def handleMatch(self, m):
return m.group(2)
class EscapePattern(Pattern):
""" Return an escaped character. """
def handleMatch(self, m):
char = m.group(2)
if char in self.markdown.ESCAPED_CHARS:
return '%s%s%s' % (util.STX, ord(char), util.ETX)
else:
return None
class SimpleTagPattern(Pattern):
"""
Return element of type `tag` with a text attribute of group(3)
of a Pattern.
"""
def __init__(self, pattern, tag):
Pattern.__init__(self, pattern)
self.tag = tag
def handleMatch(self, m):
el = util.etree.Element(self.tag)
el.text = m.group(3)
return el
class SubstituteTagPattern(SimpleTagPattern):
""" Return an element of type `tag` with no children. """
def handleMatch(self, m):
return util.etree.Element(self.tag)
class BacktickPattern(Pattern):
""" Return a `<code>` element containing the matching text. """
def __init__(self, pattern):
Pattern.__init__(self, pattern)
self.ESCAPED_BSLASH = '%s%s%s' % (util.STX, ord('\\'), util.ETX)
self.tag = 'code'
def handleMatch(self, m):
if m.group(4):
el = util.etree.Element(self.tag)
el.text = util.AtomicString(m.group(4).strip())
return el
else:
return m.group(2).replace('\\\\', self.ESCAPED_BSLASH)
class DoubleTagPattern(SimpleTagPattern):
"""Return a ElementTree element nested in tag2 nested in tag1.
Useful for strong emphasis etc.
"""
def handleMatch(self, m):
tag1, tag2 = self.tag.split(",")
el1 = util.etree.Element(tag1)
el2 = util.etree.SubElement(el1, tag2)
el2.text = m.group(3)
if len(m.groups()) == 5:
el2.tail = m.group(4)
return el1
class HtmlPattern(Pattern):
""" Store raw inline html and return a placeholder. """
def handleMatch(self, m):
rawhtml = self.unescape(m.group(2))
place_holder = self.markdown.htmlStash.store(rawhtml)
return place_holder
def unescape(self, text):
""" Return unescaped text given text with an inline placeholder. """
try:
stash = self.markdown.treeprocessors['inline'].stashed_nodes
except KeyError: # pragma: no cover
return text
def get_stash(m):
id = m.group(1)
value = stash.get(id)
if value is not None:
try:
return self.markdown.serializer(value)
except Exception:
return r'\%s' % value
return util.INLINE_PLACEHOLDER_RE.sub(get_stash, text)
class LinkPattern(Pattern):
""" Return a link element from the given match. """
def handleMatch(self, m):
el = util.etree.Element("a")
el.text = m.group(2)
title = m.group(13)
href = m.group(9)
if href:
if href[0] == "<":
href = href[1:-1]
el.set("href", self.sanitize_url(self.unescape(href.strip())))
else:
el.set("href", "")
if title:
title = dequote(self.unescape(title))
el.set("title", title)
return el
def sanitize_url(self, url):
"""
Sanitize a url against xss attacks in "safe_mode".
Rather than specifically blacklisting `javascript:alert("XSS")` and all
its aliases (see <http://ha.ckers.org/xss.html>), we whitelist known
safe url formats. Most urls contain a network location, however some
are known not to (i.e.: mailto links). Script urls do not contain a
location. Additionally, for `javascript:...`, the scheme would be
"javascript" but some aliases will appear to `urlparse()` to have no
scheme. On top of that relative links (i.e.: "foo/bar.html") have no
scheme. Therefore we must check "path", "parameters", "query" and
"fragment" for any literal colons. We don't check "scheme" for colons
because it *should* never have any and "netloc" must allow the form:
`username:password@host:port`.
"""
if not self.markdown.safeMode:
# Return immediately bipassing parsing.
return url
try:
scheme, netloc, path, params, query, fragment = url = urlparse(url)
except ValueError: # pragma: no cover
# Bad url - so bad it couldn't be parsed.
return ''
locless_schemes = ['', 'mailto', 'news']
allowed_schemes = locless_schemes + ['http', 'https', 'ftp', 'ftps']
if scheme not in allowed_schemes:
# Not a known (allowed) scheme. Not safe.
return ''
if netloc == '' and scheme not in locless_schemes: # pragma: no cover
# This should not happen. Treat as suspect.
return ''
for part in url[2:]:
if ":" in part:
# A colon in "path", "parameters", "query"
# or "fragment" is suspect.
return ''
# Url passes all tests. Return url as-is.
return urlunparse(url)
class ImagePattern(LinkPattern):
""" Return a img element from the given match. """
def handleMatch(self, m):
el = util.etree.Element("img")
src_parts = m.group(9).split()
if src_parts:
src = src_parts[0]
if src[0] == "<" and src[-1] == ">":
src = src[1:-1]
el.set('src', self.sanitize_url(self.unescape(src)))
else:
el.set('src', "")
if len(src_parts) > 1:
el.set('title', dequote(self.unescape(" ".join(src_parts[1:]))))
if self.markdown.enable_attributes:
truealt = handleAttributes(m.group(2), el)
else:
truealt = m.group(2)
el.set('alt', self.unescape(truealt))
return el
class ReferencePattern(LinkPattern):
""" Match to a stored reference and return link element. """
NEWLINE_CLEANUP_RE = re.compile(r'[ ]?\n', re.MULTILINE)
def handleMatch(self, m):
try:
id = m.group(9).lower()
except IndexError:
id = None
if not id:
# if we got something like "[Google][]" or "[Google]"
# we'll use "google" as the id
id = m.group(2).lower()
# Clean up linebreaks in id
id = self.NEWLINE_CLEANUP_RE.sub(' ', id)
if id not in self.markdown.references: # ignore undefined refs
return None
href, title = self.markdown.references[id]
text = m.group(2)
return self.makeTag(href, title, text)
def makeTag(self, href, title, text):
el = util.etree.Element('a')
el.set('href', self.sanitize_url(href))
if title:
el.set('title', title)
el.text = text
return el
class ImageReferencePattern(ReferencePattern):
""" Match to a stored reference and return img element. """
def makeTag(self, href, title, text):
el = util.etree.Element("img")
el.set("src", self.sanitize_url(href))
if title:
el.set("title", title)
if self.markdown.enable_attributes:
text = handleAttributes(text, el)
el.set("alt", self.unescape(text))
return el
class AutolinkPattern(Pattern):
""" Return a link Element given an autolink (`<http://example/com>`). """
def handleMatch(self, m):
el = util.etree.Element("a")
el.set('href', self.unescape(m.group(2)))
el.text = util.AtomicString(m.group(2))
return el
class AutomailPattern(Pattern):
"""
Return a mailto link Element given an automail link (`<foo@example.com>`).
"""
def handleMatch(self, m):
el = util.etree.Element('a')
email = self.unescape(m.group(2))
if email.startswith("mailto:"):
email = email[len("mailto:"):]
def codepoint2name(code):
"""Return entity definition by code, or the code if not defined."""
entity = entities.codepoint2name.get(code)
if entity:
return "%s%s;" % (util.AMP_SUBSTITUTE, entity)
else:
return "%s#%d;" % (util.AMP_SUBSTITUTE, code)
letters = [codepoint2name(ord(letter)) for letter in email]
el.text = util.AtomicString(''.join(letters))
mailto = "mailto:" + email
mailto = "".join([util.AMP_SUBSTITUTE + '#%d;' %
ord(letter) for letter in mailto])
el.set('href', mailto)
return el
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