"""A parser for HTML and XHTML."""

# This file is based on sgmllib.py, but the API is slightly different.

# XXX There should be a way to distinguish between PCDATA (parsed

# character data -- the normal case), RCDATA (replaceable character

# data -- only char and entity references and end tags are special)

# and CDATA (character data -- only end tags are special).

import _markupbase

import re

# Regular expressions used for parsing

interesting_normal = re.compile('[&<]')

interesting_cdata = re.compile(r'<(/|\Z)')

incomplete = re.compile('&[a-zA-Z#]')

entityref = re.compile('&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]')

charref = re.compile('&#(?:[0-9]+|[xX][0-9a-fA-F]+)[^0-9a-fA-F]')

starttagopen = re.compile('<[a-zA-Z]')

piclose = re.compile('>')

commentclose = re.compile(r'--\s*>')

tagfind = re.compile('[a-zA-Z][-.a-zA-Z0-9:_]*')

attrfind = re.compile(

r'\s*([a-zA-Z_][-.:a-zA-Z_0-9]*)(\s*=\s*'

r'(\'[^\']*\'|"[^"]*"|[-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~@]*))?')

locatestarttagend = re.compile(r"""

<[a-zA-Z][-.a-zA-Z0-9:_]* # tag name

(?:\s+ # whitespace before attribute name

(?:[a-zA-Z_][-.:a-zA-Z0-9_]* # attribute name

(?:\s*=\s* # value indicator

(?:'[^']*' # LITA-enclosed value

|\"[^\"]*\" # LIT-enclosed value

|[^'\">\s]+ # bare value

)

)?

)

)*

\s* # trailing whitespace

""", re.VERBOSE)

endendtag = re.compile('>')

endtagfind = re.compile('</\s*([a-zA-Z][-.a-zA-Z0-9:_]*)\s*>')

class HTMLParseError(Exception):

"""Exception raised for all parse errors."""

def __init__(self, msg, position=(None, None)):

assert msg

self.msg = msg

self.lineno = position[0]

self.offset = position[1]

def __str__(self):

result = self.msg

if self.lineno is not None:

result = result + ", at line %d" % self.lineno

if self.offset is not None:

result = result + ", column %d" % (self.offset + 1)

return result

class HTMLParser(_markupbase.ParserBase):

"""Find tags and other markup and call handler functions.

Usage:

p = HTMLParser()

p.feed(data)

...

p.close()

Start tags are handled by calling self.handle_starttag() or

self.handle_startendtag(); end tags by self.handle_endtag(). The

data between tags is passed from the parser to the derived class

by calling self.handle_data() with the data as argument (the data

may be split up in arbitrary chunks). Entity references are

passed by calling self.handle_entityref() with the entity

reference as the argument. Numeric character references are

passed to self.handle_charref() with the string containing the

reference as the argument.

"""

CDATA_CONTENT_ELEMENTS = ("script", "style")

def __init__(self):

"""Initialize and reset this instance."""

self.reset()

def reset(self):

"""Reset this instance. Loses all unprocessed data."""

self.rawdata = ''

self.lasttag = '???'

self.interesting = interesting_normal

_markupbase.ParserBase.reset(self)

def feed(self, data):

"""Feed data to the parser.

Call this as often as you want, with as little or as much text

as you want (may include '\n').

"""

self.rawdata = self.rawdata + data

self.goahead(0)

def close(self):

"""Handle any buffered data."""

self.goahead(1)

def error(self, message):

raise HTMLParseError(message, self.getpos())

__starttag_text = None

def get_starttag_text(self):

"""Return full source of start tag: '<...>'."""

return self.__starttag_text

def set_cdata_mode(self):

self.interesting = interesting_cdata

def clear_cdata_mode(self):

self.interesting = interesting_normal

# Internal -- handle data as far as reasonable. May leave state

# and data to be processed by a subsequent call. If 'end' is

# true, force handling all data as if followed by EOF marker.

def goahead(self, end):

rawdata = self.rawdata

i = 0

n = len(rawdata)

while i < n:

match = self.interesting.search(rawdata, i) # < or &

if match:

j = match.start()

else:

j = n

if i < j: self.handle_data(rawdata[i:j])

i = self.updatepos(i, j)

if i == n: break

startswith = rawdata.startswith

if startswith('<', i):

if starttagopen.match(rawdata, i): # < + letter

k = self.parse_starttag(i)

elif startswith("</", i):

k = self.parse_endtag(i)

elif startswith("<!--", i):

k = self.parse_comment(i)

elif startswith("<?", i):

k = self.parse_pi(i)

elif startswith("<!", i):

k = self.parse_declaration(i)

elif (i + 1) < n:

self.handle_data("<")

k = i + 1

else:

break

if k < 0:

if end:

self.error("EOF in middle of construct")

break

i = self.updatepos(i, k)

elif startswith("&#", i):

match = charref.match(rawdata, i)

if match:

name = match.group()[2:-1]

self.handle_charref(name)

k = match.end()

if not startswith(';', k-1):

k = k - 1

i = self.updatepos(i, k)

continue

else:

break

elif startswith('&', i):

match = entityref.match(rawdata, i)

if match:

name = match.group(1)

self.handle_entityref(name)

k = match.end()

if not startswith(';', k-1):

k = k - 1

i = self.updatepos(i, k)

continue

match = incomplete.match(rawdata, i)

if match:

# match.group() will contain at least 2 chars

if end and match.group() == rawdata[i:]:

self.error("EOF in middle of entity or char ref")

# incomplete

break

elif (i + 1) < n:

# not the end of the buffer, and can't be confused

# with some other construct

self.handle_data("&")

i = self.updatepos(i, i + 1)

else:

break

else:

assert 0, "interesting.search() lied"

# end while

if end and i < n:

self.handle_data(rawdata[i:n])

i = self.updatepos(i, n)

self.rawdata = rawdata[i:]

# Internal -- parse processing instr, return end or -1 if not terminated

def parse_pi(self, i):

rawdata = self.rawdata

assert rawdata[i:i+2] == '<?', 'unexpected call to parse_pi()'

match = piclose.search(rawdata, i+2) # >

if not match:

return -1

j = match.start()

self.handle_pi(rawdata[i+2: j])

j = match.end()

return j

# Internal -- handle starttag, return end or -1 if not terminated

def parse_starttag(self, i):

self.__starttag_text = None

endpos = self.check_for_whole_start_tag(i)

if endpos < 0:

return endpos

rawdata = self.rawdata

self.__starttag_text = rawdata[i:endpos]

# Now parse the data between i+1 and j into a tag and attrs

attrs = []

match = tagfind.match(rawdata, i+1)

assert match, 'unexpected call to parse_starttag()'

k = match.end()

self.lasttag = tag = rawdata[i+1:k].lower()

while k < endpos:

m = attrfind.match(rawdata, k)

if not m:

break

attrname, rest, attrvalue = m.group(1, 2, 3)

if not rest:

attrvalue = None

elif attrvalue[:1] == '\'' == attrvalue[-1:] or \

attrvalue[:1] == '"' == attrvalue[-1:]:

attrvalue = attrvalue[1:-1]

attrvalue = self.unescape(attrvalue)

attrs.append((attrname.lower(), attrvalue))

k = m.end()

end = rawdata[k:endpos].strip()

if end not in (">", "/>"):

lineno, offset = self.getpos()

if "\n" in self.__starttag_text:

lineno = lineno + self.__starttag_text.count("\n")

offset = len(self.__starttag_text) \

- self.__starttag_text.rfind("\n")

else:

offset = offset + len(self.__starttag_text)

self.error("junk characters in start tag: %r"

% (rawdata[k:endpos][:20],))

if end.endswith('/>'):

# XHTML-style empty tag: <span attr="value" />

self.handle_startendtag(tag, attrs)

else:

self.handle_starttag(tag, attrs)

if tag in self.CDATA_CONTENT_ELEMENTS:

self.set_cdata_mode()

return endpos

# Internal -- check to see if we have a complete starttag; return end

# or -1 if incomplete.

def check_for_whole_start_tag(self, i):

rawdata = self.rawdata

m = locatestarttagend.match(rawdata, i)

if m:

j = m.end()

next = rawdata[j:j+1]

if next == ">":

return j + 1

if next == "/":

if rawdata.startswith("/>", j):

return j + 2

if rawdata.startswith("/", j):

# buffer boundary

return -1

# else bogus input

self.updatepos(i, j + 1)

self.error("malformed empty start tag")

if next == "":

# end of input

return -1

if next in ("abcdefghijklmnopqrstuvwxyz=/"

"ABCDEFGHIJKLMNOPQRSTUVWXYZ"):

# end of input in or before attribute value, or we have the

# '/' from a '/>' ending

return -1

self.updatepos(i, j)

self.error("malformed start tag")

raise AssertionError("we should not get here!")

# Internal -- parse endtag, return end or -1 if incomplete

def parse_endtag(self, i):

rawdata = self.rawdata

assert rawdata[i:i+2] == "</", "unexpected call to parse_endtag"

match = endendtag.search(rawdata, i+1) # >

if not match:

return -1

j = match.end()

match = endtagfind.match(rawdata, i) # </ + tag + >

if not match:

self.error("bad end tag: %r" % (rawdata[i:j],))

tag = match.group(1)

self.handle_endtag(tag.lower())

self.clear_cdata_mode()

return j

# Overridable -- finish processing of start+end tag: <tag.../>

def handle_startendtag(self, tag, attrs):

self.handle_starttag(tag, attrs)

self.handle_endtag(tag)

# Overridable -- handle start tag

def handle_starttag(self, tag, attrs):

pass

# Overridable -- handle end tag

def handle_endtag(self, tag):

pass

# Overridable -- handle character reference

def handle_charref(self, name):

pass

# Overridable -- handle entity reference

def handle_entityref(self, name):

pass

# Overridable -- handle data

def handle_data(self, data):

pass

# Overridable -- handle comment

def handle_comment(self, data):

pass

# Overridable -- handle declaration

def handle_decl(self, decl):

pass

# Overridable -- handle processing instruction

def handle_pi(self, data):

pass

def unknown_decl(self, data):

self.error("unknown declaration: %r" % (data,))

# Internal -- helper to remove special character quoting

entitydefs = None

def unescape(self, s):

if '&' not in s:

return s

def replaceEntities(s):

s = s.groups()[0]

if s[0] == "#":

s = s[1:]

if s[0] in ['x','X']:

c = int(s[1:], 16)

else:

c = int(s)

return chr(c)

else:

# Cannot use name2codepoint directly, because HTMLParser

# supports apos, which is not part of HTML 4

import html.entities

if HTMLParser.entitydefs is None:

entitydefs = HTMLParser.entitydefs = {'apos':"'"}

for k, v in html.entities.name2codepoint.items():

entitydefs[k] = chr(v)

try:

return self.entitydefs[s]

except KeyError:

return '&'+s+';'

return re.sub(r"&(#?[xX]?(?:[0-9a-fA-F]+|\w{1,8}));",

replaceEntities, s)