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import re
import string
from .util import escape_url
PREVENT_BACKSLASH = r'(?<!\\)(?:\\\\)*'
PUNCTUATION = r'[' + re.escape(string.punctuation) + r']'
LINK_LABEL = r'(?:[^\\\[\]]|\\.){0,500}'
LINK_BRACKET_START = re.compile(r'[ \t]*\n?[ \t]*<')
LINK_BRACKET_RE = re.compile(r'<([^<>\n\\\x00]*)>')
LINK_HREF_BLOCK_RE = re.compile(r'[ \t]*\n?[ \t]*([^\s]+)(?:\s|$)')
LINK_HREF_INLINE_RE = re.compile(
r'[ \t]*\n?[ \t]*([^ \t\n]*?)(?:[ \t\n]|'
r'(?:' + PREVENT_BACKSLASH + r'\)))'
)
LINK_TITLE_RE = re.compile(
r'[ \t\n]+('
r'"(?:\\' + PUNCTUATION + r'|[^"\x00])*"|' # "title"
r"'(?:\\" + PUNCTUATION + r"|[^'\x00])*'" # 'title'
r')'
)
PAREN_END_RE = re.compile(r'\s*\)')
HTML_TAGNAME = r'[A-Za-z][A-Za-z0-9-]*'
HTML_ATTRIBUTES = (
r'(?:\s+[A-Za-z_:][A-Za-z0-9_.:-]*'
r'(?:\s*=\s*(?:[^ !"\'=<>`]+|\'[^\']*?\'|"[^\"]*?"))?)*'
)
BLOCK_TAGS = (
'address', 'article', 'aside', 'base', 'basefont', 'blockquote',
'body', 'caption', 'center', 'col', 'colgroup', 'dd', 'details',
'dialog', 'dir', 'div', 'dl', 'dt', 'fieldset', 'figcaption',
'figure', 'footer', 'form', 'frame', 'frameset', 'h1', 'h2', 'h3',
'h4', 'h5', 'h6', 'head', 'header', 'hr', 'html', 'iframe',
'legend', 'li', 'link', 'main', 'menu', 'menuitem', 'meta', 'nav',
'noframes', 'ol', 'optgroup', 'option', 'p', 'param', 'section',
'source', 'summary', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead',
'title', 'tr', 'track', 'ul'
)
PRE_TAGS = ('pre', 'script', 'style', 'textarea')
_INLINE_LINK_LABEL_RE = re.compile(LINK_LABEL + r'\]')
_INLINE_SQUARE_BRACKET_RE = re.compile(PREVENT_BACKSLASH + r'[\[\]]')
_ESCAPE_CHAR_RE = re.compile(r'\\(' + PUNCTUATION + r')')
def unescape_char(text):
return _ESCAPE_CHAR_RE.sub(r'\1', text)
def parse_link_text(src, pos):
level = 1
found = False
start_pos = pos
while pos < len(src):
m = _INLINE_SQUARE_BRACKET_RE.search(src, pos)
if not m:
break
pos = m.end()
marker = m.group(0)
if marker == ']':
level -= 1
if level == 0:
found = True
break
else:
level += 1
if found:
text = src[start_pos:pos-1]
return text, pos
return None, None
def parse_link_label(src, start_pos):
m = _INLINE_LINK_LABEL_RE.match(src, start_pos)
if m:
label = m.group(0)[:-1]
return label, m.end()
return None, None
def parse_link_href(src, start_pos, block=False):
m = LINK_BRACKET_START.match(src, start_pos)
if m:
start_pos = m.end() - 1
m = LINK_BRACKET_RE.match(src, start_pos)
if m:
return m.group(1), m.end()
return None, None
if block:
m = LINK_HREF_BLOCK_RE.match(src, start_pos)
else:
m = LINK_HREF_INLINE_RE.match(src, start_pos)
if not m:
return None, None
end_pos = m.end()
href = m.group(1)
if block and src[end_pos - 1] == href[-1]:
return href, end_pos
return href, end_pos - 1
def parse_link_title(src, start_pos, max_pos):
m = LINK_TITLE_RE.match(src, start_pos, max_pos)
if m:
title = m.group(1)[1:-1]
title = unescape_char(title)
return title, m.end()
return None, None
def parse_link(src, pos):
href, href_pos = parse_link_href(src, pos)
if href is None:
return None, None
title, title_pos = parse_link_title(src, href_pos, len(src))
next_pos = title_pos or href_pos
m = PAREN_END_RE.match(src, next_pos)
if not m:
return None, None
href = unescape_char(href)
attrs = {'url': escape_url(href)}
if title:
attrs['title'] = title
return attrs, m.end()
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