484 lines
16 KiB
Python
484 lines
16 KiB
Python
"""
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INLINE PATTERNS
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=============================================================================
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Inline patterns such as *emphasis* are handled by means of auxiliary
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objects, one per pattern. Pattern objects must be instances of classes
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that extend markdown.Pattern. Each pattern object uses a single regular
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expression and needs support the following methods:
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pattern.getCompiledRegExp() # returns a regular expression
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pattern.handleMatch(m) # takes a match object and returns
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# an ElementTree element or just plain text
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All of python markdown's built-in patterns subclass from Pattern,
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but you can add additional patterns that don't.
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Also note that all the regular expressions used by inline must
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capture the whole block. For this reason, they all start with
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'^(.*)' and end with '(.*)!'. In case with built-in expression
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Pattern takes care of adding the "^(.*)" and "(.*)!".
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Finally, the order in which regular expressions are applied is very
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important - e.g. if we first replace http://.../ links with <a> tags
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and _then_ try to replace inline html, we would end up with a mess.
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So, we apply the expressions in the following order:
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* escape and backticks have to go before everything else, so
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that we can preempt any markdown patterns by escaping them.
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* then we handle auto-links (must be done before inline html)
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* then we handle inline HTML. At this point we will simply
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replace all inline HTML strings with a placeholder and add
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the actual HTML to a hash.
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* then inline images (must be done before links)
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* then bracketed links, first regular then reference-style
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* finally we apply strong and emphasis
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"""
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from __future__ import absolute_import
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from __future__ import unicode_literals
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from . import util
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from . import odict
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import re
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try:
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from urllib.parse import urlparse, urlunparse
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except ImportError:
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from urlparse import urlparse, urlunparse
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try:
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from html import entities
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except ImportError:
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import htmlentitydefs as entities
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def build_inlinepatterns(md_instance, **kwargs):
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""" Build the default set of inline patterns for Markdown. """
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inlinePatterns = odict.OrderedDict()
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inlinePatterns["backtick"] = BacktickPattern(BACKTICK_RE)
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inlinePatterns["escape"] = EscapePattern(ESCAPE_RE, md_instance)
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inlinePatterns["reference"] = ReferencePattern(REFERENCE_RE, md_instance)
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inlinePatterns["link"] = LinkPattern(LINK_RE, md_instance)
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inlinePatterns["image_link"] = ImagePattern(IMAGE_LINK_RE, md_instance)
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inlinePatterns["image_reference"] = \
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ImageReferencePattern(IMAGE_REFERENCE_RE, md_instance)
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inlinePatterns["short_reference"] = \
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ReferencePattern(SHORT_REF_RE, md_instance)
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inlinePatterns["autolink"] = AutolinkPattern(AUTOLINK_RE, md_instance)
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inlinePatterns["automail"] = AutomailPattern(AUTOMAIL_RE, md_instance)
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inlinePatterns["linebreak"] = SubstituteTagPattern(LINE_BREAK_RE, 'br')
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if md_instance.safeMode != 'escape':
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inlinePatterns["html"] = HtmlPattern(HTML_RE, md_instance)
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inlinePatterns["entity"] = HtmlPattern(ENTITY_RE, md_instance)
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inlinePatterns["not_strong"] = SimpleTextPattern(NOT_STRONG_RE)
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inlinePatterns["strong_em"] = DoubleTagPattern(STRONG_EM_RE, 'strong,em')
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inlinePatterns["strong"] = SimpleTagPattern(STRONG_RE, 'strong')
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inlinePatterns["emphasis"] = SimpleTagPattern(EMPHASIS_RE, 'em')
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if md_instance.smart_emphasis:
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inlinePatterns["emphasis2"] = SimpleTagPattern(SMART_EMPHASIS_RE, 'em')
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else:
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inlinePatterns["emphasis2"] = SimpleTagPattern(EMPHASIS_2_RE, 'em')
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return inlinePatterns
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"""
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The actual regular expressions for patterns
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-----------------------------------------------------------------------------
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"""
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NOBRACKET = r'[^\]\[]*'
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BRK = ( r'\[('
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+ (NOBRACKET + r'(\[')*6
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+ (NOBRACKET+ r'\])*')*6
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+ NOBRACKET + r')\]' )
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NOIMG = r'(?<!\!)'
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BACKTICK_RE = r'(?<!\\)(`+)(.+?)(?<!`)\2(?!`)' # `e=f()` or ``e=f("`")``
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ESCAPE_RE = r'\\(.)' # \<
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EMPHASIS_RE = r'(\*)([^\*]+)\2' # *emphasis*
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STRONG_RE = r'(\*{2}|_{2})(.+?)\2' # **strong**
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STRONG_EM_RE = r'(\*{3}|_{3})(.+?)\2' # ***strong***
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SMART_EMPHASIS_RE = r'(?<!\w)(_)(?!_)(.+?)(?<!_)\2(?!\w)' # _smart_emphasis_
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EMPHASIS_2_RE = r'(_)(.+?)\2' # _emphasis_
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LINK_RE = NOIMG + BRK + \
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r'''\(\s*(<.*?>|((?:(?:\(.*?\))|[^\(\)]))*?)\s*((['"])(.*?)\12\s*)?\)'''
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# [text](url) or [text](<url>) or [text](url "title")
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IMAGE_LINK_RE = r'\!' + BRK + r'\s*\((<.*?>|([^\)]*))\)'
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#  or 
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REFERENCE_RE = NOIMG + BRK+ r'\s?\[([^\]]*)\]' # [Google][3]
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SHORT_REF_RE = NOIMG + r'\[([^\]]+)\]' # [Google]
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IMAGE_REFERENCE_RE = r'\!' + BRK + '\s?\[([^\]]*)\]' # ![alt text][2]
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NOT_STRONG_RE = r'((^| )(\*|_)( |$))' # stand-alone * or _
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AUTOLINK_RE = r'<((?:[Ff]|[Hh][Tt])[Tt][Pp][Ss]?://[^>]*)>' # <http://www.123.com>
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AUTOMAIL_RE = r'<([^> \!]*@[^> ]*)>' # <me@example.com>
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HTML_RE = r'(\<([a-zA-Z/][^\>]*?|\!--.*?--)\>)' # <...>
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ENTITY_RE = r'(&[\#a-zA-Z0-9]*;)' # &
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LINE_BREAK_RE = r' \n' # two spaces at end of line
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def dequote(string):
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"""Remove quotes from around a string."""
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if ( ( string.startswith('"') and string.endswith('"'))
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or (string.startswith("'") and string.endswith("'")) ):
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return string[1:-1]
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else:
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return string
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ATTR_RE = re.compile("\{@([^\}]*)=([^\}]*)}") # {@id=123}
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def handleAttributes(text, parent):
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"""Set values of an element based on attribute definitions ({@id=123})."""
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def attributeCallback(match):
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parent.set(match.group(1), match.group(2).replace('\n', ' '))
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return ATTR_RE.sub(attributeCallback, text)
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"""
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The pattern classes
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-----------------------------------------------------------------------------
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"""
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class Pattern(object):
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"""Base class that inline patterns subclass. """
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def __init__(self, pattern, markdown_instance=None):
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"""
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Create an instant of an inline pattern.
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Keyword arguments:
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* pattern: A regular expression that matches a pattern
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"""
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self.pattern = pattern
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self.compiled_re = re.compile("^(.*?)%s(.*?)$" % pattern,
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re.DOTALL | re.UNICODE)
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# Api for Markdown to pass safe_mode into instance
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self.safe_mode = False
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if markdown_instance:
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self.markdown = markdown_instance
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def getCompiledRegExp(self):
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""" Return a compiled regular expression. """
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return self.compiled_re
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def handleMatch(self, m):
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"""Return a ElementTree element from the given match.
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Subclasses should override this method.
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Keyword arguments:
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* m: A re match object containing a match of the pattern.
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"""
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pass
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def type(self):
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""" Return class name, to define pattern type """
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return self.__class__.__name__
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def unescape(self, text):
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""" Return unescaped text given text with an inline placeholder. """
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try:
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stash = self.markdown.treeprocessors['inline'].stashed_nodes
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except KeyError:
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return text
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def itertext(el):
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' Reimplement Element.itertext for older python versions '
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tag = el.tag
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if not isinstance(tag, util.string_type) and tag is not None:
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return
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if el.text:
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yield el.text
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for e in el:
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for s in itertext(e):
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yield s
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if e.tail:
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yield e.tail
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def get_stash(m):
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id = m.group(1)
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if id in stash:
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value = stash.get(id)
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if isinstance(value, util.string_type):
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return value
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else:
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# An etree Element - return text content only
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return ''.join(itertext(value))
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return util.INLINE_PLACEHOLDER_RE.sub(get_stash, text)
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class SimpleTextPattern(Pattern):
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""" Return a simple text of group(2) of a Pattern. """
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def handleMatch(self, m):
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text = m.group(2)
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if text == util.INLINE_PLACEHOLDER_PREFIX:
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return None
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return text
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class EscapePattern(Pattern):
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""" Return an escaped character. """
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def handleMatch(self, m):
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char = m.group(2)
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if char in self.markdown.ESCAPED_CHARS:
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return '%s%s%s' % (util.STX, ord(char), util.ETX)
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else:
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return '\\%s' % char
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class SimpleTagPattern(Pattern):
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"""
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Return element of type `tag` with a text attribute of group(3)
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of a Pattern.
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"""
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def __init__ (self, pattern, tag):
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Pattern.__init__(self, pattern)
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self.tag = tag
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def handleMatch(self, m):
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el = util.etree.Element(self.tag)
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el.text = m.group(3)
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return el
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class SubstituteTagPattern(SimpleTagPattern):
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""" Return an element of type `tag` with no children. """
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def handleMatch (self, m):
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return util.etree.Element(self.tag)
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class BacktickPattern(Pattern):
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""" Return a `<code>` element containing the matching text. """
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def __init__ (self, pattern):
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Pattern.__init__(self, pattern)
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self.tag = "code"
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def handleMatch(self, m):
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el = util.etree.Element(self.tag)
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el.text = util.AtomicString(m.group(3).strip())
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return el
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class DoubleTagPattern(SimpleTagPattern):
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"""Return a ElementTree element nested in tag2 nested in tag1.
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Useful for strong emphasis etc.
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"""
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def handleMatch(self, m):
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tag1, tag2 = self.tag.split(",")
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el1 = util.etree.Element(tag1)
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el2 = util.etree.SubElement(el1, tag2)
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el2.text = m.group(3)
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return el1
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class HtmlPattern(Pattern):
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""" Store raw inline html and return a placeholder. """
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def handleMatch (self, m):
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rawhtml = self.unescape(m.group(2))
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place_holder = self.markdown.htmlStash.store(rawhtml)
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return place_holder
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def unescape(self, text):
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""" Return unescaped text given text with an inline placeholder. """
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try:
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stash = self.markdown.treeprocessors['inline'].stashed_nodes
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except KeyError:
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return text
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def get_stash(m):
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id = m.group(1)
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value = stash.get(id)
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if value is not None:
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try:
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return self.markdown.serializer(value)
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except:
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return '\%s' % value
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return util.INLINE_PLACEHOLDER_RE.sub(get_stash, text)
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class LinkPattern(Pattern):
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""" Return a link element from the given match. """
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def handleMatch(self, m):
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el = util.etree.Element("a")
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el.text = m.group(2)
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title = m.group(13)
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href = m.group(9)
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if href:
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if href[0] == "<":
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href = href[1:-1]
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el.set("href", self.sanitize_url(self.unescape(href.strip())))
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else:
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el.set("href", "")
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if title:
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title = dequote(self.unescape(title))
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el.set("title", title)
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return el
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def sanitize_url(self, url):
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"""
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Sanitize a url against xss attacks in "safe_mode".
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Rather than specifically blacklisting `javascript:alert("XSS")` and all
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its aliases (see <http://ha.ckers.org/xss.html>), we whitelist known
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safe url formats. Most urls contain a network location, however some
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are known not to (i.e.: mailto links). Script urls do not contain a
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location. Additionally, for `javascript:...`, the scheme would be
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"javascript" but some aliases will appear to `urlparse()` to have no
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scheme. On top of that relative links (i.e.: "foo/bar.html") have no
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scheme. Therefore we must check "path", "parameters", "query" and
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"fragment" for any literal colons. We don't check "scheme" for colons
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because it *should* never have any and "netloc" must allow the form:
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`username:password@host:port`.
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"""
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url = url.replace(' ', '%20')
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if not self.markdown.safeMode:
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# Return immediately bipassing parsing.
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return url
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try:
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scheme, netloc, path, params, query, fragment = url = urlparse(url)
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except ValueError:
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# Bad url - so bad it couldn't be parsed.
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return ''
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locless_schemes = ['', 'mailto', 'news']
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allowed_schemes = locless_schemes + ['http', 'https', 'ftp', 'ftps']
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if scheme not in allowed_schemes:
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# Not a known (allowed) scheme. Not safe.
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return ''
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if netloc == '' and scheme not in locless_schemes:
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# This should not happen. Treat as suspect.
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return ''
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for part in url[2:]:
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if ":" in part:
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# A colon in "path", "parameters", "query" or "fragment" is suspect.
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return ''
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# Url passes all tests. Return url as-is.
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return urlunparse(url)
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class ImagePattern(LinkPattern):
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""" Return a img element from the given match. """
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def handleMatch(self, m):
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el = util.etree.Element("img")
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src_parts = m.group(9).split()
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if src_parts:
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src = src_parts[0]
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if src[0] == "<" and src[-1] == ">":
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src = src[1:-1]
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el.set('src', self.sanitize_url(self.unescape(src)))
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else:
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el.set('src', "")
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if len(src_parts) > 1:
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el.set('title', dequote(self.unescape(" ".join(src_parts[1:]))))
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if self.markdown.enable_attributes:
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truealt = handleAttributes(m.group(2), el)
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else:
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truealt = m.group(2)
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el.set('alt', self.unescape(truealt))
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return el
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class ReferencePattern(LinkPattern):
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""" Match to a stored reference and return link element. """
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NEWLINE_CLEANUP_RE = re.compile(r'[ ]?\n', re.MULTILINE)
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def handleMatch(self, m):
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try:
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id = m.group(9).lower()
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except IndexError:
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id = None
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if not id:
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# if we got something like "[Google][]" or "[Goggle]"
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# we'll use "google" as the id
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id = m.group(2).lower()
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# Clean up linebreaks in id
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id = self.NEWLINE_CLEANUP_RE.sub(' ', id)
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if not id in self.markdown.references: # ignore undefined refs
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return None
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href, title = self.markdown.references[id]
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text = m.group(2)
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return self.makeTag(href, title, text)
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def makeTag(self, href, title, text):
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el = util.etree.Element('a')
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el.set('href', self.sanitize_url(href))
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if title:
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el.set('title', title)
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el.text = text
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return el
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class ImageReferencePattern(ReferencePattern):
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""" Match to a stored reference and return img element. """
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def makeTag(self, href, title, text):
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el = util.etree.Element("img")
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el.set("src", self.sanitize_url(href))
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if title:
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el.set("title", title)
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if self.markdown.enable_attributes:
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text = handleAttributes(text, el)
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el.set("alt", self.unescape(text))
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return el
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class AutolinkPattern(Pattern):
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""" Return a link Element given an autolink (`<http://example/com>`). """
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def handleMatch(self, m):
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el = util.etree.Element("a")
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el.set('href', self.unescape(m.group(2)))
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el.text = util.AtomicString(m.group(2))
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return el
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class AutomailPattern(Pattern):
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"""
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Return a mailto link Element given an automail link (`<foo@example.com>`).
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"""
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def handleMatch(self, m):
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el = util.etree.Element('a')
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email = self.unescape(m.group(2))
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if email.startswith("mailto:"):
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email = email[len("mailto:"):]
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def codepoint2name(code):
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"""Return entity definition by code, or the code if not defined."""
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entity = entities.codepoint2name.get(code)
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if entity:
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return "%s%s;" % (util.AMP_SUBSTITUTE, entity)
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else:
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return "%s#%d;" % (util.AMP_SUBSTITUTE, code)
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letters = [codepoint2name(ord(letter)) for letter in email]
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el.text = util.AtomicString(''.join(letters))
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mailto = "mailto:" + email
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mailto = "".join([util.AMP_SUBSTITUTE + '#%d;' %
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ord(letter) for letter in mailto])
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el.set('href', mailto)
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return el
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