# This file was originally based on the meld3 package version 2.0.0

# (https://pypi.org/project/meld3/2.0.0/). The meld3 package is not

# called out separately in Supervisor's license or copyright files

# because meld3 had the same authors, copyright, and license as

# Supervisor at the time this file was bundled with Supervisor.

import email

import re

from xml.etree.ElementTree import (

Comment,

ElementPath,

ProcessingInstruction,

QName,

TreeBuilder,

XMLParser,

parse as et_parse

)

from supervisor.compat import (

PY2,

htmlentitydefs,

HTMLParser,

StringIO,

StringTypes,

unichr,

as_bytes,

as_string,

)

AUTOCLOSE = "p", "li", "tr", "th", "td", "head", "body"

IGNOREEND = "img", "hr", "meta", "link", "br"

_BLANK = as_bytes('', encoding='latin1')

_SPACE = as_bytes(' ', encoding='latin1')

_EQUAL = as_bytes('=', encoding='latin1')

_QUOTE = as_bytes('"', encoding='latin1')

_OPEN_TAG_START = as_bytes("<", encoding='latin1')

_CLOSE_TAG_START = as_bytes("</", encoding='latin1')

_OPEN_TAG_END = _CLOSE_TAG_END = as_bytes(">", encoding='latin1')

_SELF_CLOSE = as_bytes(" />", encoding='latin1')

_OMITTED_TEXT = as_bytes(' [...]\n', encoding='latin1')

_COMMENT_START = as_bytes('<!-- ', encoding='latin1')

_COMMENT_END = as_bytes(' -->', encoding='latin1')

_PI_START = as_bytes('<?', encoding='latin1')

_PI_END = as_bytes('?>', encoding='latin1')

_AMPER_ESCAPED = as_bytes('&amp;', encoding='latin1')

_LT = as_bytes('<', encoding='latin1')

_LT_ESCAPED = as_bytes('&lt;', encoding='latin1')

_QUOTE_ESCAPED = as_bytes("&quot;", encoding='latin1')

_XML_PROLOG_BEGIN = as_bytes('<?xml version="1.0"', encoding='latin1')

_ENCODING = as_bytes('encoding', encoding='latin1')

_XML_PROLOG_END = as_bytes('?>\n', encoding='latin1')

_DOCTYPE_BEGIN = as_bytes('<!DOCTYPE', encoding='latin1')

_PUBLIC = as_bytes('PUBLIC', encoding='latin1')

_DOCTYPE_END = as_bytes('>\n', encoding='latin1')

if PY2:

def encode(text, encoding):

return text.encode(encoding)

else:

def encode(text, encoding):

if not isinstance(text, bytes):

text = text.encode(encoding)

return text

# replace element factory

def Replace(text, structure=False):

element = _MeldElementInterface(Replace, {})

element.text = text

element.structure = structure

return element

class PyHelper:

def findmeld(self, node, name, default=None):

iterator = self.getiterator(node)

for element in iterator:

val = element.attrib.get(_MELD_ID)

if val == name:

return element

return default

def clone(self, node, parent=None):

element = _MeldElementInterface(node.tag, node.attrib.copy())

element.text = node.text

element.tail = node.tail

element.structure = node.structure

if parent is not None:

# avoid calling self.append to reduce function call overhead

parent._children.append(element)

element.parent = parent

for child in node._children:

self.clone(child, element)

return element

def _bfclone(self, nodes, parent):

L = []

for node in nodes:

element = _MeldElementInterface(node.tag, node.attrib.copy())

element.parent = parent

element.text = node.text

element.tail = node.tail

element.structure = node.structure

if node._children:

self._bfclone(node._children, element)

L.append(element)

parent._children = L

def bfclone(self, node, parent=None):

element = _MeldElementInterface(node.tag, node.attrib.copy())

element.text = node.text

element.tail = node.tail

element.structure = node.structure

element.parent = parent

if parent is not None:

parent._children.append(element)

if node._children:

self._bfclone(node._children, element)

return element

def getiterator(self, node, tag=None):

nodes = []

if tag == "*":

tag = None

if tag is None or node.tag == tag:

nodes.append(node)

for element in node._children:

nodes.extend(self.getiterator(element, tag))

return nodes

def content(self, node, text, structure=False):

node.text = None

replacenode = Replace(text, structure)

replacenode.parent = node

replacenode.text = text

replacenode.structure = structure

node._children = [replacenode]

helper = PyHelper()

_MELD_NS_URL = 'https://github.com/Supervisor/supervisor'

_MELD_PREFIX = '{%s}' % _MELD_NS_URL

_MELD_LOCAL = 'id'

_MELD_ID = '%s%s' % (_MELD_PREFIX, _MELD_LOCAL)

_MELD_SHORT_ID = 'meld:%s' % _MELD_LOCAL

_XHTML_NS_URL = 'http://www.w3.org/1999/xhtml'

_XHTML_PREFIX = '{%s}' % _XHTML_NS_URL

_XHTML_PREFIX_LEN = len(_XHTML_PREFIX)

_marker = []

class doctype:

# lookup table for ease of use in external code

html_strict = ('HTML', '-//W3C//DTD HTML 4.01//EN',

'http://www.w3.org/TR/html4/strict.dtd')

html = ('HTML', '-//W3C//DTD HTML 4.01 Transitional//EN',

'http://www.w3.org/TR/html4/loose.dtd')

xhtml_strict = ('html', '-//W3C//DTD XHTML 1.0 Strict//EN',

'http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd')

xhtml = ('html', '-//W3C//DTD XHTML 1.0 Transitional//EN',

'http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd')

class _MeldElementInterface:

parent = None

attrib = None

text = None

tail = None

structure = None

# overrides to reduce MRU lookups

def __init__(self, tag, attrib):

self.tag = tag

self.attrib = attrib

self._children = []

def __repr__(self):

return "<MeldElement %s at %x>" % (self.tag, id(self))

def __len__(self):

return len(self._children)

def __getitem__(self, index):

return self._children[index]

def __getslice__(self, start, stop):

return self._children[start:stop]

def getchildren(self):

return self._children

def find(self, path):

return ElementPath.find(self, path)

def findtext(self, path, default=None):

return ElementPath.findtext(self, path, default)

def findall(self, path):

return ElementPath.findall(self, path)

def clear(self):

self.attrib.clear()

self._children = []

self.text = self.tail = None

def get(self, key, default=None):

return self.attrib.get(key, default)

def set(self, key, value):

self.attrib[key] = value

def keys(self):

return list(self.attrib.keys())

def items(self):

return list(self.attrib.items())

def getiterator(self, *ignored_args, **ignored_kw):

# we ignore any tag= passed in to us, originally because it was too

# painfail to support in the old C extension, now for b/w compat

return helper.getiterator(self)

# overrides to support parent pointers and factories

def __setitem__(self, index, element):

if isinstance(index, slice):

for e in element:

e.parent = self

else:

element.parent = self

self._children[index] = element

# TODO: Can __setslice__ be removed now?

def __setslice__(self, start, stop, elements):

for element in elements:

element.parent = self

self._children[start:stop] = list(elements)

def append(self, element):

self._children.append(element)

element.parent = self

def insert(self, index, element):

self._children.insert(index, element)

element.parent = self

def __delitem__(self, index):

if isinstance(index, slice):

for ob in self._children[index]:

ob.parent = None

else:

self._children[index].parent = None

ob = self._children[index]

del self._children[index]

# TODO: Can __delslice__ be removed now?

def __delslice__(self, start, stop):

obs = self._children[start:stop]

for ob in obs:

ob.parent = None

del self._children[start:stop]

def remove(self, element):

self._children.remove(element)

element.parent = None

def makeelement(self, tag, attrib):

return self.__class__(tag, attrib)

# meld-specific

def __mod__(self, other):

""" Fill in the text values of meld nodes in tree; only

support dictionarylike operand (sequence operand doesn't seem

to make sense here)"""

return self.fillmelds(**other)

def fillmelds(self, **kw):

""" Fill in the text values of meld nodes in tree using the

keyword arguments passed in; use the keyword keys as meld ids

and the keyword values as text that should fill in the node

text on which that meld id is found. Return a list of keys

from **kw that were not able to be found anywhere in the tree.

Never raises an exception. """

unfilled = []

for k in kw:

node = self.findmeld(k)

if node is None:

unfilled.append(k)

else:

node.text = kw[k]

return unfilled

def fillmeldhtmlform(self, **kw):

""" Perform magic to 'fill in' HTML form element values from a

dictionary. Unlike 'fillmelds', the type of element being

'filled' is taken into consideration.

Perform a 'findmeld' on each key in the dictionary and use the

value that corresponds to the key to perform mutation of the

tree, changing data in what is presumed to be one or more HTML

form elements according to the following rules::

If the found element is an 'input group' (its meld id ends

with the string ':inputgroup'), set the 'checked' attribute

on the appropriate subelement which has a 'value' attribute

which matches the dictionary value. Also remove the

'checked' attribute from every other 'input' subelement of

the input group. If no input subelement's value matches the

dictionary value, this key is treated as 'unfilled'.

If the found element is an 'input type=text', 'input

type=hidden', 'input type=submit', 'input type=password',

'input type=reset' or 'input type=file' element, replace its

'value' attribute with the value.

If the found element is an 'input type=checkbox' or 'input

type='radio' element, set its 'checked' attribute to true if

the dict value is true, or remove its 'checked' attribute if

the dict value is false.

If the found element is a 'select' element and the value

exists in the 'value=' attribute of one of its 'option'

subelements, change that option's 'selected' attribute to

true and mark all other option elements as unselected. If

the select element does not contain an option with a value

that matches the dictionary value, do nothing and return

this key as unfilled.

If the found element is a 'textarea' or any other kind of

element, replace its text with the value.

If the element corresponding to the key is not found,

do nothing and treat the key as 'unfilled'.

Return a list of 'unfilled' keys, representing meld ids

present in the dictionary but not present in the element tree

or meld ids which could not be filled due to the lack of any

matching subelements for 'select' nodes or 'inputgroup' nodes.

"""

unfilled = []

for k in kw:

node = self.findmeld(k)

if node is None:

unfilled.append(k)

continue

val = kw[k]

if k.endswith(':inputgroup'):

# an input group is a list of input type="checkbox" or

# input type="radio" elements that can be treated as a group

# because they attempt to specify the same value

found = []

unfound = []

for child in node.findall('input'):

input_type = child.attrib.get('type', '').lower()

if input_type not in ('checkbox', 'radio'):

continue

input_val = child.attrib.get('value', '')

if val == input_val:

found.append(child)

else:

unfound.append(child)

if not found:

unfilled.append(k)

else:

for option in found:

option.attrib['checked'] = 'checked'

for option in unfound:

try:

del option.attrib['checked']

except KeyError:

pass

else:

tag = node.tag.lower()

if tag == 'input':

input_type = node.attrib.get('type', 'text').lower()

# fill in value attrib for most input types

if input_type in ('hidden', 'submit', 'text',

'password', 'reset', 'file'):

node.attrib['value'] = val

# unless it's a checkbox or radio attribute, then we

# fill in its checked attribute

elif input_type in ('checkbox', 'radio'):

if val:

node.attrib['checked'] = 'checked'

else:

try:

del node.attrib['checked']

except KeyError:

pass

else:

unfilled.append(k)

elif tag == 'select':

# if the node is a select node, we want to select

# the value matching val, otherwise it's unfilled

found = []

unfound = []

for option in node.findall('option'):

if option.attrib.get('value', '') == val:

found.append(option)

else:

unfound.append(option)

if not found:

unfilled.append(k)

else:

for option in found:

option.attrib['selected'] = 'selected'

for option in unfound:

try:

del option.attrib['selected']

except KeyError:

pass

else:

node.text = kw[k]

return unfilled

def findmeld(self, name, default=None):

""" Find a node in the tree that has a 'meld id' corresponding

to 'name'. Iterate over all subnodes recursively looking for a

node which matches. If we can't find the node, return None."""

# this could be faster if we indexed all the meld nodes in the

# tree; we just walk the whole hierarchy now.

result = helper.findmeld(self, name)

if result is None:

return default

return result

def findmelds(self):

""" Find all nodes that have a meld id attribute and return

the found nodes in a list"""

return self.findwithattrib(_MELD_ID)

def findwithattrib(self, attrib, value=None):

""" Find all nodes that have an attribute named 'attrib'. If

'value' is not None, omit nodes on which the attribute value

does not compare equally to 'value'. Return the found nodes in

a list."""

iterator = helper.getiterator(self)

elements = []

for element in iterator:

attribval = element.attrib.get(attrib)

if attribval is not None:

if value is None:

elements.append(element)

else:

if value == attribval:

elements.append(element)

return elements

# ZPT-alike methods

def repeat(self, iterable, childname=None):

"""repeats an element with values from an iterable. If

'childname' is not None, repeat the element on which the

repeat is called, otherwise find the child element with a

'meld:id' matching 'childname' and repeat that. The element

is repeated within its parent element (nodes that are created

as a result of a repeat share the same parent). This method

returns an iterable; the value of each iteration is a

two-sequence in the form (newelement, data). 'newelement' is

a clone of the template element (including clones of its

children) which has already been seated in its parent element

in the template. 'data' is a value from the passed in

iterable. Changing 'newelement' (typically based on values

from 'data') mutates the element 'in place'."""

if childname:

element = self.findmeld(childname)

else:

element = self

parent = element.parent

# creating a list is faster than yielding a generator (py 2.4)

L = []

first = True

for thing in iterable:

if first is True:

clone = element

else:

clone = helper.bfclone(element, parent)

L.append((clone, thing))

first = False

return L

def replace(self, text, structure=False):

""" Replace this element with a Replace node in our parent with

the text 'text' and return the index of our position in

our parent. If we have no parent, do nothing, and return None.

Pass the 'structure' flag to the replace node so it can do the right

thing at render time. """

parent = self.parent

i = self.deparent()

if i is not None:

# reduce function call overhead by not calliing self.insert

node = Replace(text, structure)

parent._children.insert(i, node)

node.parent = parent

return i

def content(self, text, structure=False):

""" Delete this node's children and append a Replace node that

contains text. Always return None. Pass the 'structure' flag

to the replace node so it can do the right thing at render

time."""

helper.content(self, text, structure)

def attributes(self, **kw):

""" Set attributes on this node. """

for k, v in kw.items():

# prevent this from getting to the parser if possible

if not isinstance(k, StringTypes):

raise ValueError('do not set non-stringtype as key: %s' % k)

if not isinstance(v, StringTypes):

raise ValueError('do not set non-stringtype as val: %s' % v)

self.attrib[k] = kw[k]

# output methods

def write_xmlstring(self, encoding=None, doctype=None, fragment=False,

declaration=True, pipeline=False):

data = []

write = data.append

if not fragment:

if declaration:

_write_declaration(write, encoding)

if doctype:

_write_doctype(write, doctype)

_write_xml(write, self, encoding, {}, pipeline)

return _BLANK.join(data)

def write_xml(self, file, encoding=None, doctype=None,

fragment=False, declaration=True, pipeline=False):

""" Write XML to 'file' (which can be a filename or filelike object)

encoding - encoding string (if None, 'utf-8' encoding is assumed)

Must be a recognizable Python encoding type.

doctype - 3-tuple indicating name, pubid, system of doctype.

The default is to prevent a doctype from being emitted.

fragment - True if a 'fragment' should be emitted for this node (no

declaration, no doctype). This causes both the

'declaration' and 'doctype' parameters to become ignored

if provided.

declaration - emit an xml declaration header (including an encoding

if it's not None). The default is to emit the

doctype.

pipeline - preserve 'meld' namespace identifiers in output

for use in pipelining

"""

if not hasattr(file, "write"):

file = open(file, "wb")

data = self.write_xmlstring(encoding, doctype, fragment, declaration,

pipeline)

file.write(data)

def write_htmlstring(self, encoding=None, doctype=doctype.html,

fragment=False):

data = []

write = data.append

if encoding is None:

encoding = 'utf8'

if not fragment:

if doctype:

_write_doctype(write, doctype)

_write_html(write, self, encoding, {})

joined = _BLANK.join(data)

return joined

def write_html(self, file, encoding=None, doctype=doctype.html,

fragment=False):

""" Write HTML to 'file' (which can be a filename or filelike object)

encoding - encoding string (if None, 'utf-8' encoding is assumed).

Unlike XML output, this is not used in a declaration,

but it is used to do actual character encoding during

output. Must be a recognizable Python encoding type.

doctype - 3-tuple indicating name, pubid, system of doctype.

The default is the value of doctype.html (HTML 4.0

'loose')

fragment - True if a "fragment" should be omitted (no doctype).

This overrides any provided "doctype" parameter if

provided.

Namespace'd elements and attributes have their namespaces removed

during output when writing HTML, so pipelining cannot be performed.

HTML is not valid XML, so an XML declaration header is never emitted.

"""

if not hasattr(file, "write"):

file = open(file, "wb")

page = self.write_htmlstring(encoding, doctype, fragment)

file.write(page)

def write_xhtmlstring(self, encoding=None, doctype=doctype.xhtml,

fragment=False, declaration=False, pipeline=False):

data = []

write = data.append

if not fragment:

if declaration:

_write_declaration(write, encoding)

if doctype:

_write_doctype(write, doctype)

_write_xml(write, self, encoding, {}, pipeline, xhtml=True)

return _BLANK.join(data)

def write_xhtml(self, file, encoding=None, doctype=doctype.xhtml,

fragment=False, declaration=False, pipeline=False):

""" Write XHTML to 'file' (which can be a filename or filelike object)

encoding - encoding string (if None, 'utf-8' encoding is assumed)

Must be a recognizable Python encoding type.

doctype - 3-tuple indicating name, pubid, system of doctype.

The default is the value of doctype.xhtml (XHTML

'loose').

fragment - True if a 'fragment' should be emitted for this node (no

declaration, no doctype). This causes both the

'declaration' and 'doctype' parameters to be ignored.

declaration - emit an xml declaration header (including an encoding

string if 'encoding' is not None)

pipeline - preserve 'meld' namespace identifiers in output

for use in pipelining

"""

if not hasattr(file, "write"):

file = open(file, "wb")

page = self.write_xhtmlstring(encoding, doctype, fragment, declaration,

pipeline)

file.write(page)

def clone(self, parent=None):

""" Create a clone of an element. If parent is not None,

append the element to the parent. Recurse as necessary to create

a deep clone of the element. """

return helper.bfclone(self, parent)

def deparent(self):

""" Remove ourselves from our parent node (de-parent) and return

the index of the parent which was deleted. """

i = self.parentindex()

if i is not None:

del self.parent[i]

return i

def parentindex(self):

""" Return the parent node index in which we live """

parent = self.parent

if parent is not None:

return parent._children.index(self)

def shortrepr(self, encoding=None):

data = []

_write_html(data.append, self, encoding, {}, maxdepth=2)

return _BLANK.join(data)

def diffmeld(self, other):

""" Compute the meld element differences from this node (the

source) to 'other' (the target). Return a dictionary of

sequences in the form {'unreduced:

{'added':[], 'removed':[], 'moved':[]},

'reduced':

{'added':[], 'removed':[], 'moved':[]},}

"""

srcelements = self.findmelds()

tgtelements = other.findmelds()

srcids = [ x.meldid() for x in srcelements ]

tgtids = [ x.meldid() for x in tgtelements ]

removed = []

for srcelement in srcelements:

if srcelement.meldid() not in tgtids:

removed.append(srcelement)

added = []

for tgtelement in tgtelements:

if tgtelement.meldid() not in srcids:

added.append(tgtelement)

moved = []

for srcelement in srcelements:

srcid = srcelement.meldid()

if srcid in tgtids:

i = tgtids.index(srcid)

tgtelement = tgtelements[i]

if not sharedlineage(srcelement, tgtelement):

moved.append(tgtelement)

unreduced = {'added':added, 'removed':removed, 'moved':moved}

moved_reduced = diffreduce(moved)

added_reduced = diffreduce(added)

removed_reduced = diffreduce(removed)

reduced = {'moved':moved_reduced, 'added':added_reduced,

'removed':removed_reduced}

return {'unreduced':unreduced,

'reduced':reduced}

def meldid(self):

return self.attrib.get(_MELD_ID)

def lineage(self):

L = []

parent = self

while parent is not None:

L.append(parent)

parent = parent.parent

return L

class MeldTreeBuilder(TreeBuilder):

def __init__(self):

TreeBuilder.__init__(self, element_factory=_MeldElementInterface)

self.meldids = {}

def start(self, tag, attrs):

elem = TreeBuilder.start(self, tag, attrs)

for key, value in attrs.items():

if key == _MELD_ID:

if value in self.meldids:

raise ValueError('Repeated meld id "%s" in source' %

value)

self.meldids[value] = 1

break

return elem

def comment(self, data):

self.start(Comment, {})

self.data(data)

self.end(Comment)

def doctype(self, name, pubid, system):

pass

class HTMLXMLParser(HTMLParser):

""" A mostly-cut-and-paste of ElementTree's HTMLTreeBuilder that

does special meld3 things (like preserve comments and munge meld

ids). Subclassing is not possible due to private attributes. :-("""

def __init__(self, builder=None, encoding=None):

self.__stack = []

if builder is None:

builder = MeldTreeBuilder()

self.builder = builder

self.encoding = encoding or "iso-8859-1"

try:

# ``convert_charrefs`` was added in Python 3.4. Set it to avoid

# "DeprecationWarning: The value of convert_charrefs will become

# True in 3.5. You are encouraged to set the value explicitly."

HTMLParser.__init__(self, convert_charrefs=False)

except TypeError:

HTMLParser.__init__(self)

self.meldids = {}

def close(self):

HTMLParser.close(self)

self.meldids = {}

return self.builder.close()

def handle_starttag(self, tag, attrs):

if tag == "meta":

# look for encoding directives

http_equiv = content = None

for k, v in attrs:

if k == "http-equiv":

http_equiv = v.lower()

elif k == "content":

content = v

if http_equiv == "content-type" and content:

# use email to parse the http header

msg = email.message_from_string(

"%s: %s\n\n" % (http_equiv, content)

)

encoding = msg.get_param("charset")

if encoding:

self.encoding = encoding

if tag in AUTOCLOSE:

if self.__stack and self.__stack[-1] == tag:

self.handle_endtag(tag)

self.__stack.append(tag)

attrib = {}

if attrs:

for k, v in attrs:

if k == _MELD_SHORT_ID:

k = _MELD_ID

if self.meldids.get(v):

raise ValueError('Repeated meld id "%s" in source' %

v)

self.meldids[v] = 1

else:

k = k.lower()

attrib[k] = v

self.builder.start(tag, attrib)

if tag in IGNOREEND:

self.__stack.pop()

self.builder.end(tag)

def handle_endtag(self, tag):

if tag in IGNOREEND:

return

lasttag = self.__stack.pop()

if tag != lasttag and lasttag in AUTOCLOSE:

self.handle_endtag(lasttag)

self.builder.end(tag)

def handle_charref(self, char):

if char[:1] == "x":

char = int(char[1:], 16)

else:

char = int(char)

self.builder.data(unichr(char))

def handle_entityref(self, name):

entity = htmlentitydefs.entitydefs.get(name)

if entity:

if len(entity) == 1:

entity = ord(entity)

else:

entity = int(entity[2:-1])

self.builder.data(unichr(entity))

else:

self.unknown_entityref(name)

def handle_data(self, data):

if isinstance(data, bytes):

data = as_string(data, self.encoding)

self.builder.data(data)

def unknown_entityref(self, name):

pass # ignore by default; override if necessary

def handle_comment(self, data):

self.builder.start(Comment, {})

self.builder.data(data)

self.builder.end(Comment)

def do_parse(source, parser):

root = et_parse(source, parser=parser).getroot()

iterator = root.getiterator()

for p in iterator:

for c in p:

c.parent = p

return root

def parse_xml(source):

""" Parse source (a filelike object) into an element tree. If

html is true, use a parser that can resolve somewhat ambiguous

HTML into XHTML. Otherwise use a 'normal' parser only."""

builder = MeldTreeBuilder()

parser = XMLParser(target=builder)

return do_parse(source, parser)

def parse_html(source, encoding=None):

builder = MeldTreeBuilder()

parser = HTMLXMLParser(builder, encoding)

return do_parse(source, parser)

def parse_xmlstring(text):

source = StringIO(text)

return parse_xml(source)

def parse_htmlstring(text, encoding=None):

source = StringIO(text)

return parse_html(source, encoding)

attrib_needs_escaping = re.compile(r'[&"<]').search

cdata_needs_escaping = re.compile(r'[&<]').search

def _both_case(mapping):

# Add equivalent upper-case keys to mapping.

lc_keys = list(mapping.keys())

for k in lc_keys:

mapping[k.upper()] = mapping[k]

_HTMLTAGS_UNBALANCED = {'area':1, 'base':1, 'basefont':1, 'br':1, 'col':1,

'frame':1, 'hr':1, 'img':1, 'input':1, 'isindex':1,

'link':1, 'meta':1, 'param':1}

_both_case(_HTMLTAGS_UNBALANCED)

_HTMLTAGS_NOESCAPE = {'script':1, 'style':1}

_both_case(_HTMLTAGS_NOESCAPE)

_HTMLATTRS_BOOLEAN = {'selected':1, 'checked':1, 'compact':1, 'declare':1,

'defer':1, 'disabled':1, 'ismap':1, 'multiple':1,

'nohref':1, 'noresize':1, 'noshade':1, 'nowrap':1}

_both_case(_HTMLATTRS_BOOLEAN)

def _write_html(write, node, encoding, namespaces, depth=-1, maxdepth=None):

""" Walk 'node', calling 'write' with bytes(?).

"""

if encoding is None:

encoding = 'utf-8'

tag = node.tag

tail = node.tail

text = node.text

tail = node.tail

to_write = _BLANK

if tag is Replace:

if not node.structure:

if cdata_needs_escaping(text):

text = _escape_cdata(text)

write(encode(text, encoding))

elif tag is Comment:

if cdata_needs_escaping(text):

text = _escape_cdata(text)

write(encode('<!-- ' + text + ' -->', encoding))

elif tag is ProcessingInstruction:

if cdata_needs_escaping(text):

text = _escape_cdata(text)

write(encode('<!-- ' + text + ' -->', encoding))

else:

xmlns_items = [] # new namespaces in this scope

try:

if tag[:1] == "{":

if tag[:_XHTML_PREFIX_LEN] == _XHTML_PREFIX:

tag = tag[_XHTML_PREFIX_LEN:]

else:

tag, xmlns = fixtag(tag, namespaces)

if xmlns:

xmlns_items.append(xmlns)

except TypeError:

_raise_serialization_error(tag)

to_write += _OPEN_TAG_START + encode(tag, encoding)

attrib = node.attrib

if attrib is not None:

if len(attrib) > 1:

attrib_keys = list(attrib.keys())

attrib_keys.sort()

else:

attrib_keys = attrib

for k in attrib_keys:

try:

if k[:1] == "{":

continue

except TypeError:

_raise_serialization_error(k)

if k in _HTMLATTRS_BOOLEAN:

to_write += _SPACE + encode(k, encoding)

else:

v = attrib[k]

to_write += _encode_attrib(k, v, encoding)

for k, v in xmlns_items:

to_write += _encode_attrib(k, v, encoding)

to_write += _OPEN_TAG_END

if text is not None and text:

if tag in _HTMLTAGS_NOESCAPE:

to_write += encode(text, encoding)

elif cdata_needs_escaping(text):

to_write += _escape_cdata(text)

else:

to_write += encode(text,encoding)

write(to_write)

for child in node._children:

if maxdepth is not None:

depth = depth + 1

if depth < maxdepth:

_write_html(write, child, encoding, namespaces, depth,

maxdepth)

elif depth == maxdepth and text:

write(_OMITTED_TEXT)

else:

_write_html(write, child, encoding, namespaces, depth, maxdepth)

if text or node._children or tag not in _HTMLTAGS_UNBALANCED:

write(_CLOSE_TAG_START + encode(tag, encoding) + _CLOSE_TAG_END)

if tail:

if cdata_needs_escaping(tail):