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ebook-converter/ebook_converter/ebooks/oeb/parse_utils.py
gryf 0f9792df36 Convert calibre modules to ebook_converter. 
Here is the first batch of modules, which are needed for converting
several formats to LRF. Some of the logic has been change, more cleanups
will follow.
2020-04-19 15:16:48 +02:00

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#!/usr/bin/env python2
# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
from __future__ import absolute_import, division, print_function, unicode_literals
__license__ = 'GPL v3'
__copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
__docformat__ = 'restructuredtext en'
import re
from lxml import etree, html
from ebook_converter import xml_replace_entities, force_unicode
from ebook_converter.utils.xml_parse import safe_xml_fromstring
from ebook_converter.constants import filesystem_encoding
from ebook_converter.ebooks.chardet import xml_to_unicode, strip_encoding_declarations
from ebook_converter.polyglot.builtins import iteritems, itervalues, unicode_type, string_or_bytes, map
RECOVER_PARSER = etree.XMLParser(recover=True, no_network=True, resolve_entities=False)
XHTML_NS = 'http://www.w3.org/1999/xhtml'
XMLNS_NS = 'http://www.w3.org/2000/xmlns/'
class NotHTML(Exception):
def __init__(self, root_tag):
Exception.__init__(self, 'Data is not HTML')
self.root_tag = root_tag
def barename(name):
return name.rpartition('}')[-1]
def namespace(name):
return name.rpartition('}')[0][1:]
def XHTML(name):
return '{%s}%s' % (XHTML_NS, name)
def xpath(elem, expr):
return elem.xpath(expr, namespaces={'h':XHTML_NS})
def XPath(expr):
return etree.XPath(expr, namespaces={'h':XHTML_NS})
META_XP = XPath('/h:html/h:head/h:meta[@http-equiv="Content-Type"]')
def merge_multiple_html_heads_and_bodies(root, log=None):
heads, bodies = xpath(root, '//h:head'), xpath(root, '//h:body')
if not (len(heads) > 1 or len(bodies) > 1):
return root
for child in root:
root.remove(child)
head = root.makeelement(XHTML('head'))
body = root.makeelement(XHTML('body'))
for h in heads:
for x in h:
head.append(x)
for b in bodies:
for x in b:
body.append(x)
tuple(map(root.append, (head, body)))
if log is not None:
log.warn('Merging multiple <head> and <body> sections')
return root
def clone_element(elem, nsmap={}, in_context=True):
if in_context:
maker = elem.getroottree().getroot().makeelement
else:
maker = etree.Element
nelem = maker(elem.tag, attrib=elem.attrib,
nsmap=nsmap)
nelem.text, nelem.tail = elem.text, elem.tail
nelem.extend(elem)
return nelem
def node_depth(node):
ans = 0
p = node.getparent()
while p is not None:
ans += 1
p = p.getparent()
return ans
def html5_parse(data, max_nesting_depth=100):
from html5_parser import parse
from ebook_converter.utils.cleantext import clean_xml_chars
data = parse(clean_xml_chars(data), maybe_xhtml=True, keep_doctype=False, sanitize_names=True)
# Check that the asinine HTML 5 algorithm did not result in a tree with
# insane nesting depths
for x in data.iterdescendants():
if isinstance(x.tag, string_or_bytes) and not len(x): # Leaf node
depth = node_depth(x)
if depth > max_nesting_depth:
raise ValueError('HTML 5 parsing resulted in a tree with nesting'
' depth > %d'%max_nesting_depth)
return data
def _html4_parse(data):
data = html.fromstring(data)
data.attrib.pop('xmlns', None)
for elem in data.iter(tag=etree.Comment):
if elem.text:
elem.text = elem.text.strip('-')
data = etree.tostring(data, encoding='unicode')
data = safe_xml_fromstring(data)
return data
def clean_word_doc(data, log):
prefixes = []
for match in re.finditer(r'xmlns:(\S+?)=".*?microsoft.*?"', data):
prefixes.append(match.group(1))
if prefixes:
log.warn('Found microsoft markup, cleaning...')
# Remove empty tags as they are not rendered by browsers
# but can become renderable HTML tags like <p/> if the
# document is parsed by an HTML parser
pat = re.compile(
r'<(%s):([a-zA-Z0-9]+)[^>/]*?></\1:\2>'%('|'.join(prefixes)),
re.DOTALL)
data = pat.sub('', data)
pat = re.compile(
r'<(%s):([a-zA-Z0-9]+)[^>/]*?/>'%('|'.join(prefixes)))
data = pat.sub('', data)
return data
def ensure_namespace_prefixes(node, nsmap):
namespace_uris = frozenset(itervalues(nsmap))
fnsmap = {k:v for k, v in iteritems(node.nsmap) if v not in namespace_uris}
fnsmap.update(nsmap)
if fnsmap != dict(node.nsmap):
node = clone_element(node, nsmap=fnsmap, in_context=False)
return node
class HTML5Doc(ValueError):
pass
def check_for_html5(prefix, root):
if re.search(r'<!DOCTYPE\s+html\s*>', prefix, re.IGNORECASE) is not None:
if root.xpath('//svg'):
raise HTML5Doc('This document appears to be un-namespaced HTML 5, should be parsed by the HTML 5 parser')
def parse_html(data, log=None, decoder=None, preprocessor=None,
filename='<string>', non_html_file_tags=frozenset()):
if log is None:
from ebook_converter.utils.logging import default_log
log = default_log
filename = force_unicode(filename, enc=filesystem_encoding)
if not isinstance(data, unicode_type):
if decoder is not None:
data = decoder(data)
else:
data = xml_to_unicode(data)[0]
data = strip_encoding_declarations(data)
# Remove DOCTYPE declaration as it messes up parsing
# In particular, it causes tostring to insert xmlns
# declarations, which messes up the coercing logic
pre = ''
idx = data.find('<html')
if idx == -1:
idx = data.find('<HTML')
has_html4_doctype = False
if idx > -1:
pre = data[:idx]
data = data[idx:]
if '<!DOCTYPE' in pre: # Handle user defined entities
# kindlegen produces invalid xhtml with uppercase attribute names
# if fed HTML 4 with uppercase attribute names, so try to detect
# and compensate for that.
has_html4_doctype = re.search(r'<!DOCTYPE\s+[^>]+HTML\s+4.0[^.]+>', pre) is not None
# Process private entities
user_entities = {}
for match in re.finditer(r'<!ENTITY\s+(\S+)\s+([^>]+)', pre):
val = match.group(2)
if val.startswith('"') and val.endswith('"'):
val = val[1:-1]
user_entities[match.group(1)] = val
if user_entities:
pat = re.compile(r'&(%s);'%('|'.join(list(user_entities.keys()))))
data = pat.sub(lambda m:user_entities[m.group(1)], data)
if preprocessor is not None:
data = preprocessor(data)
# There could be null bytes in data if it had &#0; entities in it
data = data.replace('\0', '')
data = raw = clean_word_doc(data, log)
# Try with more & more drastic measures to parse
try:
data = safe_xml_fromstring(data, recover=False)
check_for_html5(pre, data)
except (HTML5Doc, etree.XMLSyntaxError):
log.debug('Initial parse failed, using more'
' forgiving parsers')
raw = data = xml_replace_entities(raw)
try:
data = safe_xml_fromstring(data, recover=False)
check_for_html5(pre, data)
except (HTML5Doc, etree.XMLSyntaxError):
log.debug('Parsing %s as HTML' % filename)
data = raw
try:
data = html5_parse(data)
except Exception:
log.exception(
'HTML 5 parsing failed, falling back to older parsers')
data = _html4_parse(data)
if has_html4_doctype or data.tag == 'HTML' or (len(data) and (data[-1].get('LANG') or data[-1].get('DIR'))):
# Lower case all tag and attribute names
data.tag = data.tag.lower()
for x in data.iterdescendants():
try:
x.tag = x.tag.lower()
for key, val in list(iteritems(x.attrib)):
del x.attrib[key]
key = key.lower()
x.attrib[key] = val
except:
pass
if barename(data.tag) != 'html':
if barename(data.tag) in non_html_file_tags:
raise NotHTML(data.tag)
log.warn('File %r does not appear to be (X)HTML'%filename)
nroot = safe_xml_fromstring('<html></html>')
has_body = False
for child in list(data):
if isinstance(child.tag, (unicode_type, bytes)) and barename(child.tag) == 'body':
has_body = True
break
parent = nroot
if not has_body:
log.warn('File %r appears to be a HTML fragment'%filename)
nroot = safe_xml_fromstring('<html><body/></html>')
parent = nroot[0]
for child in list(data.iter()):
oparent = child.getparent()
if oparent is not None:
oparent.remove(child)
parent.append(child)
data = nroot
# Force into the XHTML namespace
if not namespace(data.tag):
log.warn('Forcing', filename, 'into XHTML namespace')
data.attrib['xmlns'] = XHTML_NS
data = etree.tostring(data, encoding='unicode')
try:
data = safe_xml_fromstring(data, recover=False)
except:
data = data.replace(':=', '=').replace(':>', '>')
data = data.replace('<http:/>', '')
try:
data = safe_xml_fromstring(data, recover=False)
except etree.XMLSyntaxError:
log.warn('Stripping comments from %s'%
filename)
data = re.compile(r'<!--.*?-->', re.DOTALL).sub('',
data)
data = data.replace(
"<?xml version='1.0' encoding='utf-8'?><o:p></o:p>",
'')
data = data.replace("<?xml version='1.0' encoding='utf-8'??>", '')
try:
data = safe_xml_fromstring(data)
except etree.XMLSyntaxError:
log.warn('Stripping meta tags from %s'% filename)
data = re.sub(r'<meta\s+[^>]+?>', '', data)
data = safe_xml_fromstring(data)
elif namespace(data.tag) != XHTML_NS:
# OEB_DOC_NS, but possibly others
ns = namespace(data.tag)
attrib = dict(data.attrib)
nroot = etree.Element(XHTML('html'),
nsmap={None: XHTML_NS}, attrib=attrib)
for elem in data.iterdescendants():
if isinstance(elem.tag, string_or_bytes) and \
namespace(elem.tag) == ns:
elem.tag = XHTML(barename(elem.tag))
for elem in data:
nroot.append(elem)
data = nroot
# Remove non default prefixes referring to the XHTML namespace
data = ensure_namespace_prefixes(data, {None: XHTML_NS})
data = merge_multiple_html_heads_and_bodies(data, log)
# Ensure has a <head/>
head = xpath(data, '/h:html/h:head')
head = head[0] if head else None
if head is None:
log.warn('File %s missing <head/> element' % filename)
head = etree.Element(XHTML('head'))
data.insert(0, head)
title = etree.SubElement(head, XHTML('title'))
title.text = _('Unknown')
elif not xpath(data, '/h:html/h:head/h:title'):
title = etree.SubElement(head, XHTML('title'))
title.text = _('Unknown')
# Ensure <title> is not empty
title = xpath(data, '/h:html/h:head/h:title')[0]
if not title.text or not title.text.strip():
title.text = _('Unknown')
# Remove any encoding-specifying <meta/> elements
for meta in META_XP(data):
meta.getparent().remove(meta)
meta = etree.SubElement(head, XHTML('meta'),
attrib={'http-equiv': 'Content-Type'})
meta.set('content', 'text/html; charset=utf-8') # Ensure content is second attribute
# Ensure has a <body/>
if not xpath(data, '/h:html/h:body'):
body = xpath(data, '//h:body')
if body:
body = body[0]
body.getparent().remove(body)
data.append(body)
else:
log.warn('File %s missing <body/> element' % filename)
etree.SubElement(data, XHTML('body'))
# Remove microsoft office markup
r = [x for x in data.iterdescendants(etree.Element) if 'microsoft-com' in x.tag]
for x in r:
x.tag = XHTML('span')
def remove_elem(a):
p = a.getparent()
idx = p.index(a) -1
p.remove(a)
if a.tail:
if idx < 0:
if p.text is None:
p.text = ''
p.text += a.tail
else:
if p[idx].tail is None:
p[idx].tail = ''
p[idx].tail += a.tail
# Remove hyperlinks with no content as they cause rendering
# artifacts in browser based renderers
# Also remove empty <b>, <u> and <i> tags
for a in xpath(data, '//h:a[@href]|//h:i|//h:b|//h:u'):
if a.get('id', None) is None and a.get('name', None) is None \
and len(a) == 0 and not a.text:
remove_elem(a)
# Convert <br>s with content into paragraphs as ADE can't handle
# them
for br in xpath(data, '//h:br'):
if len(br) > 0 or br.text:
br.tag = XHTML('div')
# Remove any stray text in the <head> section and format it nicely
data.text = '\n '
head = xpath(data, '//h:head')
if head:
head = head[0]
head.text = '\n '
head.tail = '\n '
for child in head:
child.tail = '\n '
child.tail = '\n '
return data
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