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411 lines
16 KiB
411 lines
16 KiB
""" |
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Footnotes Extension for Python-Markdown |
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======================================= |
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Adds footnote handling to Python-Markdown. |
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See <https://Python-Markdown.github.io/extensions/footnotes> |
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for documentation. |
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Copyright The Python Markdown Project |
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License: [BSD](https://opensource.org/licenses/bsd-license.php) |
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""" |
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from . import Extension |
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from ..blockprocessors import BlockProcessor |
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from ..inlinepatterns import InlineProcessor |
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from ..treeprocessors import Treeprocessor |
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from ..postprocessors import Postprocessor |
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from .. import util |
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from collections import OrderedDict |
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import re |
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import copy |
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import xml.etree.ElementTree as etree |
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FN_BACKLINK_TEXT = util.STX + "zz1337820767766393qq" + util.ETX |
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NBSP_PLACEHOLDER = util.STX + "qq3936677670287331zz" + util.ETX |
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RE_REF_ID = re.compile(r'(fnref)(\d+)') |
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class FootnoteExtension(Extension): |
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""" Footnote Extension. """ |
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def __init__(self, **kwargs): |
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""" Setup configs. """ |
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self.config = { |
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'PLACE_MARKER': |
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["///Footnotes Go Here///", |
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"The text string that marks where the footnotes go"], |
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'UNIQUE_IDS': |
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[False, |
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"Avoid name collisions across " |
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"multiple calls to reset()."], |
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"BACKLINK_TEXT": |
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["↩", |
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"The text string that links from the footnote " |
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"to the reader's place."], |
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"SUPERSCRIPT_TEXT": |
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["{}", |
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"The text string that links from the reader's place " |
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"to the footnote."], |
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"BACKLINK_TITLE": |
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["Jump back to footnote %d in the text", |
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"The text string used for the title HTML attribute " |
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"of the backlink. %d will be replaced by the " |
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"footnote number."], |
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"SEPARATOR": |
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[":", |
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"Footnote separator."] |
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} |
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super().__init__(**kwargs) |
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# In multiple invocations, emit links that don't get tangled. |
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self.unique_prefix = 0 |
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self.found_refs = {} |
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self.used_refs = set() |
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self.reset() |
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def extendMarkdown(self, md): |
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""" Add pieces to Markdown. """ |
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md.registerExtension(self) |
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self.parser = md.parser |
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self.md = md |
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# Insert a `blockprocessor` before `ReferencePreprocessor` |
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md.parser.blockprocessors.register(FootnoteBlockProcessor(self), 'footnote', 17) |
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# Insert an inline pattern before `ImageReferencePattern` |
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FOOTNOTE_RE = r'\[\^([^\]]*)\]' # blah blah [^1] blah |
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md.inlinePatterns.register(FootnoteInlineProcessor(FOOTNOTE_RE, self), 'footnote', 175) |
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# Insert a tree-processor that would actually add the footnote div |
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# This must be before all other tree-processors (i.e., `inline` and |
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# `codehilite`) so they can run on the the contents of the div. |
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md.treeprocessors.register(FootnoteTreeprocessor(self), 'footnote', 50) |
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# Insert a tree-processor that will run after inline is done. |
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# In this tree-processor we want to check our duplicate footnote tracker |
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# And add additional `backrefs` to the footnote pointing back to the |
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# duplicated references. |
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md.treeprocessors.register(FootnotePostTreeprocessor(self), 'footnote-duplicate', 15) |
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# Insert a postprocessor after amp_substitute processor |
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md.postprocessors.register(FootnotePostprocessor(self), 'footnote', 25) |
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def reset(self): |
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""" Clear footnotes on reset, and prepare for distinct document. """ |
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self.footnotes = OrderedDict() |
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self.unique_prefix += 1 |
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self.found_refs = {} |
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self.used_refs = set() |
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def unique_ref(self, reference, found=False): |
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""" Get a unique reference if there are duplicates. """ |
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if not found: |
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return reference |
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original_ref = reference |
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while reference in self.used_refs: |
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ref, rest = reference.split(self.get_separator(), 1) |
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m = RE_REF_ID.match(ref) |
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if m: |
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reference = '%s%d%s%s' % (m.group(1), int(m.group(2))+1, self.get_separator(), rest) |
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else: |
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reference = '%s%d%s%s' % (ref, 2, self.get_separator(), rest) |
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self.used_refs.add(reference) |
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if original_ref in self.found_refs: |
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self.found_refs[original_ref] += 1 |
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else: |
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self.found_refs[original_ref] = 1 |
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return reference |
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def findFootnotesPlaceholder(self, root): |
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""" Return ElementTree Element that contains Footnote placeholder. """ |
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def finder(element): |
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for child in element: |
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if child.text: |
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if child.text.find(self.getConfig("PLACE_MARKER")) > -1: |
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return child, element, True |
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if child.tail: |
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if child.tail.find(self.getConfig("PLACE_MARKER")) > -1: |
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return child, element, False |
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child_res = finder(child) |
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if child_res is not None: |
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return child_res |
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return None |
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res = finder(root) |
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return res |
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def setFootnote(self, id, text): |
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""" Store a footnote for later retrieval. """ |
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self.footnotes[id] = text |
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def get_separator(self): |
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""" Get the footnote separator. """ |
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return self.getConfig("SEPARATOR") |
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def makeFootnoteId(self, id): |
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""" Return footnote link id. """ |
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if self.getConfig("UNIQUE_IDS"): |
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return 'fn%s%d-%s' % (self.get_separator(), self.unique_prefix, id) |
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else: |
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return 'fn{}{}'.format(self.get_separator(), id) |
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def makeFootnoteRefId(self, id, found=False): |
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""" Return footnote back-link id. """ |
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if self.getConfig("UNIQUE_IDS"): |
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return self.unique_ref('fnref%s%d-%s' % (self.get_separator(), self.unique_prefix, id), found) |
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else: |
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return self.unique_ref('fnref{}{}'.format(self.get_separator(), id), found) |
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def makeFootnotesDiv(self, root): |
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""" Return `div` of footnotes as `etree` Element. """ |
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if not list(self.footnotes.keys()): |
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return None |
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div = etree.Element("div") |
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div.set('class', 'footnote') |
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etree.SubElement(div, "hr") |
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ol = etree.SubElement(div, "ol") |
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surrogate_parent = etree.Element("div") |
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# Backward compatibility with old '%d' placeholder |
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backlink_title = self.getConfig("BACKLINK_TITLE").replace("%d", "{}") |
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for index, id in enumerate(self.footnotes.keys(), start=1): |
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li = etree.SubElement(ol, "li") |
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li.set("id", self.makeFootnoteId(id)) |
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# Parse footnote with surrogate parent as `li` cannot be used. |
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# List block handlers have special logic to deal with `li`. |
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# When we are done parsing, we will copy everything over to `li`. |
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self.parser.parseChunk(surrogate_parent, self.footnotes[id]) |
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for el in list(surrogate_parent): |
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li.append(el) |
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surrogate_parent.remove(el) |
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backlink = etree.Element("a") |
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backlink.set("href", "#" + self.makeFootnoteRefId(id)) |
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backlink.set("class", "footnote-backref") |
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backlink.set( |
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"title", |
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backlink_title.format(index) |
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) |
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backlink.text = FN_BACKLINK_TEXT |
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if len(li): |
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node = li[-1] |
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if node.tag == "p": |
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node.text = node.text + NBSP_PLACEHOLDER |
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node.append(backlink) |
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else: |
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p = etree.SubElement(li, "p") |
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p.append(backlink) |
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return div |
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class FootnoteBlockProcessor(BlockProcessor): |
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""" Find all footnote references and store for later use. """ |
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RE = re.compile(r'^[ ]{0,3}\[\^([^\]]*)\]:[ ]*(.*)$', re.MULTILINE) |
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def __init__(self, footnotes): |
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super().__init__(footnotes.parser) |
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self.footnotes = footnotes |
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def test(self, parent, block): |
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return True |
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def run(self, parent, blocks): |
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""" Find, set, and remove footnote definitions. """ |
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block = blocks.pop(0) |
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m = self.RE.search(block) |
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if m: |
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id = m.group(1) |
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fn_blocks = [m.group(2)] |
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# Handle rest of block |
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therest = block[m.end():].lstrip('\n') |
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m2 = self.RE.search(therest) |
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if m2: |
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# Another footnote exists in the rest of this block. |
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# Any content before match is continuation of this footnote, which may be lazily indented. |
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before = therest[:m2.start()].rstrip('\n') |
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fn_blocks[0] = '\n'.join([fn_blocks[0], self.detab(before)]).lstrip('\n') |
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# Add back to blocks everything from beginning of match forward for next iteration. |
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blocks.insert(0, therest[m2.start():]) |
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else: |
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# All remaining lines of block are continuation of this footnote, which may be lazily indented. |
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fn_blocks[0] = '\n'.join([fn_blocks[0], self.detab(therest)]).strip('\n') |
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# Check for child elements in remaining blocks. |
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fn_blocks.extend(self.detectTabbed(blocks)) |
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footnote = "\n\n".join(fn_blocks) |
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self.footnotes.setFootnote(id, footnote.rstrip()) |
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if block[:m.start()].strip(): |
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# Add any content before match back to blocks as separate block |
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blocks.insert(0, block[:m.start()].rstrip('\n')) |
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return True |
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# No match. Restore block. |
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blocks.insert(0, block) |
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return False |
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def detectTabbed(self, blocks): |
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""" Find indented text and remove indent before further processing. |
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Returns: a list of blocks with indentation removed. |
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""" |
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fn_blocks = [] |
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while blocks: |
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if blocks[0].startswith(' '*4): |
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block = blocks.pop(0) |
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# Check for new footnotes within this block and split at new footnote. |
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m = self.RE.search(block) |
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if m: |
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# Another footnote exists in this block. |
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# Any content before match is continuation of this footnote, which may be lazily indented. |
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before = block[:m.start()].rstrip('\n') |
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fn_blocks.append(self.detab(before)) |
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# Add back to blocks everything from beginning of match forward for next iteration. |
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blocks.insert(0, block[m.start():]) |
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# End of this footnote. |
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break |
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else: |
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# Entire block is part of this footnote. |
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fn_blocks.append(self.detab(block)) |
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else: |
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# End of this footnote. |
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break |
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return fn_blocks |
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def detab(self, block): |
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""" Remove one level of indent from a block. |
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Preserve lazily indented blocks by only removing indent from indented lines. |
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""" |
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lines = block.split('\n') |
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for i, line in enumerate(lines): |
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if line.startswith(' '*4): |
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lines[i] = line[4:] |
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return '\n'.join(lines) |
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class FootnoteInlineProcessor(InlineProcessor): |
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""" `InlinePattern` for footnote markers in a document's body text. """ |
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def __init__(self, pattern, footnotes): |
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super().__init__(pattern) |
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self.footnotes = footnotes |
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def handleMatch(self, m, data): |
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id = m.group(1) |
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if id in self.footnotes.footnotes.keys(): |
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sup = etree.Element("sup") |
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a = etree.SubElement(sup, "a") |
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sup.set('id', self.footnotes.makeFootnoteRefId(id, found=True)) |
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a.set('href', '#' + self.footnotes.makeFootnoteId(id)) |
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a.set('class', 'footnote-ref') |
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a.text = self.footnotes.getConfig("SUPERSCRIPT_TEXT").format( |
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list(self.footnotes.footnotes.keys()).index(id) + 1 |
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) |
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return sup, m.start(0), m.end(0) |
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else: |
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return None, None, None |
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class FootnotePostTreeprocessor(Treeprocessor): |
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""" Amend footnote div with duplicates. """ |
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def __init__(self, footnotes): |
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self.footnotes = footnotes |
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def add_duplicates(self, li, duplicates): |
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""" Adjust current `li` and add the duplicates: `fnref2`, `fnref3`, etc. """ |
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for link in li.iter('a'): |
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# Find the link that needs to be duplicated. |
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if link.attrib.get('class', '') == 'footnote-backref': |
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ref, rest = link.attrib['href'].split(self.footnotes.get_separator(), 1) |
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# Duplicate link the number of times we need to |
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# and point the to the appropriate references. |
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links = [] |
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for index in range(2, duplicates + 1): |
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sib_link = copy.deepcopy(link) |
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sib_link.attrib['href'] = '%s%d%s%s' % (ref, index, self.footnotes.get_separator(), rest) |
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links.append(sib_link) |
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self.offset += 1 |
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# Add all the new duplicate links. |
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el = list(li)[-1] |
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for link in links: |
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el.append(link) |
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break |
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def get_num_duplicates(self, li): |
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""" Get the number of duplicate refs of the footnote. """ |
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fn, rest = li.attrib.get('id', '').split(self.footnotes.get_separator(), 1) |
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link_id = '{}ref{}{}'.format(fn, self.footnotes.get_separator(), rest) |
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return self.footnotes.found_refs.get(link_id, 0) |
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def handle_duplicates(self, parent): |
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""" Find duplicate footnotes and format and add the duplicates. """ |
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for li in list(parent): |
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# Check number of duplicates footnotes and insert |
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# additional links if needed. |
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count = self.get_num_duplicates(li) |
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if count > 1: |
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self.add_duplicates(li, count) |
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def run(self, root): |
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""" Crawl the footnote div and add missing duplicate footnotes. """ |
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self.offset = 0 |
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for div in root.iter('div'): |
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if div.attrib.get('class', '') == 'footnote': |
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# Footnotes should be under the first ordered list under |
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# the footnote div. So once we find it, quit. |
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for ol in div.iter('ol'): |
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self.handle_duplicates(ol) |
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break |
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class FootnoteTreeprocessor(Treeprocessor): |
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""" Build and append footnote div to end of document. """ |
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def __init__(self, footnotes): |
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self.footnotes = footnotes |
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def run(self, root): |
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footnotesDiv = self.footnotes.makeFootnotesDiv(root) |
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if footnotesDiv is not None: |
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result = self.footnotes.findFootnotesPlaceholder(root) |
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if result: |
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child, parent, isText = result |
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ind = list(parent).index(child) |
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if isText: |
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parent.remove(child) |
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parent.insert(ind, footnotesDiv) |
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else: |
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parent.insert(ind + 1, footnotesDiv) |
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child.tail = None |
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else: |
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root.append(footnotesDiv) |
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class FootnotePostprocessor(Postprocessor): |
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""" Replace placeholders with html entities. """ |
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def __init__(self, footnotes): |
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self.footnotes = footnotes |
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def run(self, text): |
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text = text.replace( |
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FN_BACKLINK_TEXT, self.footnotes.getConfig("BACKLINK_TEXT") |
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) |
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return text.replace(NBSP_PLACEHOLDER, " ") |
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def makeExtension(**kwargs): # pragma: no cover |
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""" Return an instance of the `FootnoteExtension` """ |
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return FootnoteExtension(**kwargs)
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