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Refactor tree splitting code to make it re-useable
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Kovid Goyal
parent
2b1053c05d
commit
a52407b67a
149
src/calibre/ebooks/oeb/polish/split.py
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149
src/calibre/ebooks/oeb/polish/split.py
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#!/usr/bin/env python
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# vim:fileencoding=utf-8
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from __future__ import (unicode_literals, division, absolute_import,
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print_function)
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__license__ = 'GPL v3'
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__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
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import copy
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from future_builtins import map
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from calibre.ebooks.oeb.base import barename, XPNSMAP, XPath
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from calibre.ebooks.oeb.polish.toc import node_from_loc
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def in_table(node):
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while node is not None:
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if node.tag.endswith('}table'):
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return True
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node = node.getparent()
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return False
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def adjust_split_point(split_point, log):
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'''
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Move the split point up its ancestor chain if it has no content
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before it. This handles the common case:
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<div id="chapter1"><h2>Chapter 1</h2>...</div> with a page break on the
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h2.
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'''
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sp = split_point
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while True:
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parent = sp.getparent()
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if (
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parent is None or
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barename(parent.tag) in {'body', 'html'} or
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(parent.text and parent.text.strip()) or
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parent.index(sp) > 0
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):
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break
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sp = parent
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if sp is not split_point:
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log.debug('Adjusted split point to ancestor')
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return sp
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def get_body(root):
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return root.find('h:body', namespaces=XPNSMAP)
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def do_split(split_point, log, before=True):
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'''
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Split tree into a *before* and an *after* tree at ``split_point``.
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:param split_point: The Element at which to split
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:param before: If True tree is split before split_point, otherwise after split_point
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:return: before_tree, after_tree
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'''
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if before:
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# We cannot adjust for after since moving an after split point to a
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# parent will cause breakage if the parent contains any content
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# after the original split point
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split_point = adjust_split_point(split_point, log)
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tree = split_point.getroottree()
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path = tree.getpath(split_point)
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tree, tree2 = copy.deepcopy(tree), copy.deepcopy(tree)
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root, root2 = tree.getroot(), tree2.getroot()
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body, body2 = map(get_body, (root, root2))
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split_point = root.xpath(path)[0]
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split_point2 = root2.xpath(path)[0]
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def nix_element(elem, top=True):
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# Remove elem unless top is False in which case replace elem by its
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# children
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parent = elem.getparent()
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if top:
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parent.remove(elem)
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else:
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index = parent.index(elem)
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parent[index:index+1] = list(elem.iterchildren())
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# Tree 1
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hit_split_point = False
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keep_descendants = False
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split_point_descendants = frozenset(split_point.iterdescendants())
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for elem in tuple(body.iterdescendants()):
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if elem is split_point:
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hit_split_point = True
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if before:
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nix_element(elem)
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else:
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# We want to keep the descendants of the split point in
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# Tree 1
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keep_descendants = True
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# We want the split point element, but not its tail
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elem.tail = '\n'
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continue
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if hit_split_point:
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if keep_descendants:
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if elem in split_point_descendants:
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# elem is a descendant keep it
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continue
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else:
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# We are out of split_point, so prevent further set
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# lookups of split_point_descendants
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keep_descendants = False
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nix_element(elem)
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# Tree 2
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ancestors = frozenset(XPath('ancestor::*')(split_point2))
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for elem in tuple(body2.iterdescendants()):
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if elem is split_point2:
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if not before:
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# Keep the split point element's tail, if it contains non-whitespace
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# text
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tail = elem.tail
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if tail and not tail.isspace():
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parent = elem.getparent()
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idx = parent.index(elem)
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if idx == 0:
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parent.text = (parent.text or '') + tail
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else:
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sib = parent[idx-1]
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sib.tail = (sib.tail or '') + tail
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# Remove the element itself
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nix_element(elem)
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break
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if elem in ancestors:
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# We have to preserve the ancestors as they could have CSS
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# styles that are inherited/applicable, like font or
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# width. So we only remove the text, if any.
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elem.text = '\n'
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else:
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nix_element(elem, top=False)
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body2.text = '\n'
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return tree, tree2
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def split(container, name, loc):
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root = container.parsed(name)
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split_point = node_from_loc(root, loc)
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if in_table(split_point):
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raise ValueError('Cannot split inside tables')
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if split_point.tag.endswith('}body'):
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raise ValueError('Cannot split on the <body> tag')
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@ -16,9 +16,10 @@ from lxml.etree import XPath as _XPath
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from lxml import etree
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from cssselect import HTMLTranslator
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from calibre.ebooks.oeb.base import (OEB_STYLES, XPNSMAP as NAMESPACES,
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urldefrag, rewrite_links, urlunquote, barename, XHTML, urlnormalize)
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from calibre.ebooks.epub import rules
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from calibre.ebooks.oeb.base import (OEB_STYLES, XPNSMAP as NAMESPACES,
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urldefrag, rewrite_links, urlunquote, XHTML, urlnormalize)
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from calibre.ebooks.oeb.polish.split import do_split
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XPath = functools.partial(_XPath, namespaces=NAMESPACES)
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@ -271,31 +272,6 @@ class FlowSplitter(object):
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return None
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return body[0]
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def adjust_split_point(self, root, path):
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'''
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Move the split point up its ancestor chain if it has no textual content
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before it. This handles the common case:
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<div id="chapter1"><h2>Chapter 1</h2>...</div> with a page break on the
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h2.
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'''
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sp = root.xpath(path)[0]
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while True:
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parent = sp.getparent()
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if barename(parent.tag) in ('body', 'html'):
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break
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if parent.text and parent.text.strip():
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break
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if parent.index(sp) > 0:
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break
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sp = parent
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npath = sp.getroottree().getpath(sp)
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if self.opts.verbose > 3 and npath != path:
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self.log.debug('\t\t\tMoved split point %s to %s'%(path, npath))
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return npath
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def do_split(self, tree, split_point, before):
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'''
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Split ``tree`` into a *before* and *after* tree at ``split_point``.
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@ -303,87 +279,7 @@ class FlowSplitter(object):
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:param before: If True tree is split before split_point, otherwise after split_point
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:return: before_tree, after_tree
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'''
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path = tree.getpath(split_point)
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tree, tree2 = copy.deepcopy(tree), copy.deepcopy(tree)
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root = tree.getroot()
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root2 = tree2.getroot()
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body, body2 = map(self.get_body, (root, root2))
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if before:
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# We cannot adjust for after since moving an after split point to a
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# parent will cause breakage if the parent contains any content
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# after the original split point
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path = self.adjust_split_point(root, path)
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split_point = root.xpath(path)[0]
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split_point2 = root2.xpath(path)[0]
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def nix_element(elem, top=True):
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# Remove elem unless top is False in which case replace elem by its
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# children
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parent = elem.getparent()
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if top:
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parent.remove(elem)
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else:
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index = parent.index(elem)
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parent[index:index+1] = list(elem.iterchildren())
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# Tree 1
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hit_split_point = False
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keep_descendants = False
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split_point_descendants = frozenset(split_point.iterdescendants())
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for elem in tuple(body.iterdescendants()):
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if elem is split_point:
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hit_split_point = True
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if before:
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nix_element(elem)
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else:
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# We want to keep the descendants of the split point in
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# Tree 1
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keep_descendants = True
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# We want the split point element, but not its tail
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elem.tail = '\n'
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continue
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if hit_split_point:
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if keep_descendants:
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if elem in split_point_descendants:
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# elem is a descendant keep it
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continue
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else:
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# We are out of split_point, so prevent further set
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# lookups of split_point_descendants
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keep_descendants = False
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nix_element(elem)
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# Tree 2
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ancestors = frozenset(XPath('ancestor::*')(split_point2))
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for elem in tuple(body2.iterdescendants()):
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if elem is split_point2:
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if not before:
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# Keep the split point element's tail, if it contains non-whitespace
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# text
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tail = elem.tail
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if tail and not tail.isspace():
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parent = elem.getparent()
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idx = parent.index(elem)
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if idx == 0:
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parent.text = (parent.text or '') + tail
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else:
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sib = parent[idx-1]
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sib.tail = (sib.tail or '') + tail
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# Remove the element itself
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nix_element(elem)
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break
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if elem in ancestors:
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# We have to preserve the ancestors as they could have CSS
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# styles that are inherited/applicable, like font or
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# width. So we only remove the text, if any.
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elem.text = '\n'
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else:
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nix_element(elem, top=False)
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body2.text = '\n'
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return tree, tree2
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return do_split(split_point, self.log, before=before)
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def is_page_empty(self, root):
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body = self.get_body(root)
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