Current File : //lib/calibre/calibre/ebooks/oeb/transforms/structure.py
#!/usr/bin/env python3
__license__ = 'GPL v3'
__copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
__docformat__ = 'restructuredtext en'
import re, uuid
from lxml import etree
from collections import OrderedDict, Counter
from calibre.ebooks.oeb.base import XPNSMAP, TOC, XHTML, xml2text, barename
from calibre.ebooks import ConversionError
from polyglot.builtins import itervalues
from polyglot.urllib import urlparse
def XPath(x):
try:
return etree.XPath(x, namespaces=XPNSMAP)
except etree.XPathSyntaxError:
raise ConversionError(
'The syntax of the XPath expression %s is invalid.' % repr(x))
def isspace(x):
return not x or x.replace('\xa0', '').isspace()
def at_start(elem):
' Return True if there is no content before elem '
body = XPath('ancestor-or-self::h:body')(elem)
if not body:
return True
body = body[0]
ancestors = frozenset(XPath('ancestor::*')(elem))
for x in body.iter():
if x is elem:
return True
if hasattr(getattr(x, 'tag', None), 'rpartition') and x.tag.rpartition('}')[-1] in {'img', 'svg'}:
return False
if isspace(getattr(x, 'text', None)) and (x in ancestors or isspace(getattr(x, 'tail', None))):
continue
return False
return False
class DetectStructure:
def __call__(self, oeb, opts):
self.log = oeb.log
self.oeb = oeb
self.opts = opts
self.log('Detecting structure...')
self.detect_chapters()
if self.oeb.auto_generated_toc or opts.use_auto_toc:
orig_toc = self.oeb.toc
self.oeb.toc = TOC()
self.create_level_based_toc()
if self.oeb.toc.count() < 1:
if not opts.no_chapters_in_toc and self.detected_chapters:
self.create_toc_from_chapters()
if self.oeb.toc.count() < opts.toc_threshold:
self.create_toc_from_links()
if self.oeb.toc.count() < 2 and orig_toc.count() > 2:
self.oeb.toc = orig_toc
else:
self.oeb.auto_generated_toc = True
self.log('Auto generated TOC with %d entries.' %
self.oeb.toc.count())
if opts.toc_filter is not None:
regexp = re.compile(opts.toc_filter)
for node in list(self.oeb.toc.iter()):
if not node.title or regexp.search(node.title) is not None:
self.log('Filtering', node.title if node.title else
'empty node', 'from TOC')
self.oeb.toc.remove(node)
if opts.page_breaks_before is not None:
pb_xpath = XPath(opts.page_breaks_before)
for item in oeb.spine:
for elem in pb_xpath(item.data):
try:
prev = next(elem.itersiblings(tag=etree.Element,
preceding=True))
if (barename(elem.tag) in {'h1', 'h2'} and barename(
prev.tag) in {'h1', 'h2'} and (not prev.tail or
not prev.tail.split())):
# We have two adjacent headings, do not put a page
# break on the second one
continue
except StopIteration:
pass
style = elem.get('style', '')
if style:
style += '; '
elem.set('style', style+'page-break-before:always')
for node in self.oeb.toc.iter():
if not node.title or not node.title.strip():
node.title = _('Unnamed')
if self.opts.start_reading_at:
self.detect_start_reading()
def detect_start_reading(self):
expr = self.opts.start_reading_at
try:
expr = XPath(expr)
except:
self.log.warn(
'Invalid start reading at XPath expression, ignoring: %s'%expr)
return
for item in self.oeb.spine:
if not hasattr(item.data, 'xpath'):
continue
matches = expr(item.data)
if matches:
elem = matches[0]
eid = elem.get('id', None)
if not eid:
eid = 'start_reading_at_'+str(uuid.uuid4()).replace('-', '')
elem.set('id', eid)
if 'text' in self.oeb.guide:
self.oeb.guide.remove('text')
self.oeb.guide.add('text', 'Start', item.href+'#'+eid)
self.log('Setting start reading at position to %s in %s'%(
self.opts.start_reading_at, item.href))
return
self.log.warn("Failed to find start reading at position: %s"%
self.opts.start_reading_at)
def get_toc_parts_for_xpath(self, expr):
# if an attribute is selected by the xpath expr then truncate it
# from the path and instead return it as where to find the title text
title_attribute_regex = re.compile(r'/@([-\w]+)$')
match = title_attribute_regex.search(expr)
if match is not None:
return expr[0:match.start()], match.group(1)
return expr, None
def detect_chapters(self):
self.detected_chapters = []
self.chapter_title_attribute = None
def find_matches(expr, doc):
try:
ans = XPath(expr)(doc)
len(ans)
return ans
except:
self.log.warn('Invalid chapter expression, ignoring: %s'%expr)
return []
if self.opts.chapter:
chapter_path, title_attribute = self.get_toc_parts_for_xpath(self.opts.chapter)
self.chapter_title_attribute = title_attribute
for item in self.oeb.spine:
for x in find_matches(chapter_path, item.data):
self.detected_chapters.append((item, x))
chapter_mark = self.opts.chapter_mark
page_break_before = 'display: block; page-break-before: always'
page_break_after = 'display: block; page-break-after: always'
c = Counter()
for item, elem in self.detected_chapters:
c[item] += 1
text = xml2text(elem).strip()
text = re.sub(r'\s+', ' ', text.strip())
self.log('\tDetected chapter:', text[:50])
if chapter_mark == 'none':
continue
if chapter_mark == 'rule':
mark = elem.makeelement(XHTML('hr'))
elif chapter_mark == 'pagebreak':
if c[item] < 3 and at_start(elem):
# For the first two elements in this item, check if they
# are at the start of the file, in which case inserting a
# page break in unnecessary and can lead to extra blank
# pages in the PDF Output plugin. We need to use two as
# feedbooks epubs match both a heading tag and its
# containing div with the default chapter expression.
continue
mark = elem.makeelement(XHTML('div'), style=page_break_after)
else: # chapter_mark == 'both':
mark = elem.makeelement(XHTML('hr'), style=page_break_before)
try:
elem.addprevious(mark)
except TypeError:
self.log.exception('Failed to mark chapter')
def create_level_based_toc(self):
if self.opts.level1_toc is not None:
self.add_leveled_toc_items()
def create_toc_from_chapters(self):
counter = self.oeb.toc.next_play_order()
for item, elem in self.detected_chapters:
text, href = self.elem_to_link(item, elem, self.chapter_title_attribute, counter)
self.oeb.toc.add(text, href, play_order=counter)
counter += 1
def create_toc_from_links(self):
num = 0
for item in self.oeb.spine:
for a in XPath('//h:a[@href]')(item.data):
href = a.get('href')
try:
purl = urlparse(href)
except ValueError:
self.log.warning('Ignoring malformed URL:', href)
continue
if not purl[0] or purl[0] == 'file':
href, frag = purl.path, purl.fragment
href = item.abshref(href)
if frag:
href = '#'.join((href, frag))
if not self.oeb.toc.has_href(href):
text = xml2text(a)
text = text[:100].strip()
if (not self.opts.duplicate_links_in_toc and
self.oeb.toc.has_text(text)):
continue
try:
self.oeb.toc.add(text, href,
play_order=self.oeb.toc.next_play_order())
num += 1
except ValueError:
self.oeb.log.exception('Failed to process link: %r' % href)
continue # Most likely an incorrectly URL encoded link
if self.opts.max_toc_links > 0 and \
num >= self.opts.max_toc_links:
self.log('Maximum TOC links reached, stopping.')
return
def elem_to_link(self, item, elem, title_attribute, counter):
text = ''
if title_attribute is not None:
text = elem.get(title_attribute, '')
if not text:
text = xml2text(elem).strip()
if not text:
text = elem.get('title', '')
if not text:
text = elem.get('alt', '')
text = re.sub(r'\s+', ' ', text.strip())
text = text[:1000].strip()
id = elem.get('id', 'calibre_toc_%d'%counter)
elem.set('id', id)
href = '#'.join((item.href, id))
return text, href
def add_leveled_toc_items(self):
added = OrderedDict()
added2 = OrderedDict()
counter = 1
def find_matches(expr, doc):
try:
ans = XPath(expr)(doc)
len(ans)
return ans
except:
self.log.warn('Invalid ToC expression, ignoring: %s'%expr)
return []
for document in self.oeb.spine:
previous_level1 = list(itervalues(added))[-1] if added else None
previous_level2 = list(itervalues(added2))[-1] if added2 else None
level1_toc, level1_title = self.get_toc_parts_for_xpath(self.opts.level1_toc)
for elem in find_matches(level1_toc, document.data):
text, _href = self.elem_to_link(document, elem, level1_title, counter)
counter += 1
if text:
node = self.oeb.toc.add(text, _href,
play_order=self.oeb.toc.next_play_order())
added[elem] = node
# node.add(_('Top'), _href)
if self.opts.level2_toc is not None and added:
level2_toc, level2_title = self.get_toc_parts_for_xpath(self.opts.level2_toc)
for elem in find_matches(level2_toc, document.data):
level1 = None
for item in document.data.iterdescendants():
if item in added:
level1 = added[item]
elif item == elem:
if level1 is None:
if previous_level1 is None:
break
level1 = previous_level1
text, _href = self.elem_to_link(document, elem, level2_title, counter)
counter += 1
if text:
added2[elem] = level1.add(text, _href,
play_order=self.oeb.toc.next_play_order())
break
if self.opts.level3_toc is not None and added2:
level3_toc, level3_title = self.get_toc_parts_for_xpath(self.opts.level3_toc)
for elem in find_matches(level3_toc, document.data):
level2 = None
for item in document.data.iterdescendants():
if item in added2:
level2 = added2[item]
elif item == elem:
if level2 is None:
if previous_level2 is None:
break
level2 = previous_level2
text, _href = \
self.elem_to_link(document, elem, level3_title, counter)
counter += 1
if text:
level2.add(text, _href,
play_order=self.oeb.toc.next_play_order())
break
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