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md_in_html.py
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# Python-Markdown Markdown in HTML Extension # =============================== # An implementation of [PHP Markdown Extra](http://michelf.com/projects/php-markdown/extra/)'s # parsing of Markdown syntax in raw HTML. # See https://Python-Markdown.github.io/extensions/raw_html # for documentation. # Copyright The Python Markdown Project # License: [BSD](https://opensource.org/licenses/bsd-license.php) """ An implementation of [PHP Markdown Extra](http://michelf.com/projects/php-markdown/extra/)'s parsing of Markdown syntax in raw HTML. See the [documentation](https://Python-Markdown.github.io/extensions/raw_html) for details. """ from __future__ import annotations from . import Extension from ..blockprocessors import BlockProcessor from ..preprocessors import Preprocessor from ..postprocessors import RawHtmlPostprocessor from .. import util from ..htmlparser import HTMLExtractor, blank_line_re import xml.etree.ElementTree as etree from typing import TYPE_CHECKING, Literal, Mapping if TYPE_CHECKING: # pragma: no cover from markdown import Markdown class HTMLExtractorExtra(HTMLExtractor): """ Override `HTMLExtractor` and create `etree` `Elements` for any elements which should have content parsed as Markdown. """ def __init__(self, md: Markdown, *args, **kwargs): # All block-level tags. self.block_level_tags = set(md.block_level_elements.copy()) # Block-level tags in which the content only gets span level parsing self.span_tags = set( ['address', 'dd', 'dt', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'legend', 'li', 'p', 'summary', 'td', 'th'] ) # Block-level tags which never get their content parsed. self.raw_tags = set(['canvas', 'math', 'option', 'pre', 'script', 'style', 'textarea']) super().__init__(md, *args, **kwargs) # Block-level tags in which the content gets parsed as blocks self.block_tags = set(self.block_level_tags) - (self.span_tags | self.raw_tags | self.empty_tags) self.span_and_blocks_tags = self.block_tags | self.span_tags def reset(self): """Reset this instance. Loses all unprocessed data.""" self.mdstack: list[str] = [] # When markdown=1, stack contains a list of tags self.treebuilder = etree.TreeBuilder() self.mdstate: list[Literal['block', 'span', 'off', None]] = [] super().reset() def close(self): """Handle any buffered data.""" super().close() # Handle any unclosed tags. if self.mdstack: # Close the outermost parent. `handle_endtag` will close all unclosed children. self.handle_endtag(self.mdstack[0]) def get_element(self) -> etree.Element: """ Return element from `treebuilder` and reset `treebuilder` for later use. """ element = self.treebuilder.close() self.treebuilder = etree.TreeBuilder() return element def get_state(self, tag, attrs: Mapping[str, str]) -> Literal['block', 'span', 'off', None]: """ Return state from tag and `markdown` attribute. One of 'block', 'span', or 'off'. """ md_attr = attrs.get('markdown', '0') if md_attr == 'markdown': # `<tag markdown>` is the same as `<tag markdown='1'>`. md_attr = '1' parent_state = self.mdstate[-1] if self.mdstate else None if parent_state == 'off' or (parent_state == 'span' and md_attr != '0'): # Only use the parent state if it is more restrictive than the markdown attribute. md_attr = parent_state if ((md_attr == '1' and tag in self.block_tags) or (md_attr == 'block' and tag in self.span_and_blocks_tags)): return 'block' elif ((md_attr == '1' and tag in self.span_tags) or (md_attr == 'span' and tag in self.span_and_blocks_tags)): return 'span' elif tag in self.block_level_tags: return 'off' else: # pragma: no cover return None def handle_starttag(self, tag, attrs): # Handle tags that should always be empty and do not specify a closing tag if tag in self.empty_tags and (self.at_line_start() or self.intail): attrs = {key: value if value is not None else key for key, value in attrs} if "markdown" in attrs: attrs.pop('markdown') element = etree.Element(tag, attrs) data = etree.tostring(element, encoding='unicode', method='html') else: data = self.get_starttag_text() self.handle_empty_tag(data, True) return if tag in self.block_level_tags and (self.at_line_start() or self.intail): # Valueless attribute (ex: `<tag checked>`) results in `[('checked', None)]`. # Convert to `{'checked': 'checked'}`. attrs = {key: value if value is not None else key for key, value in attrs} state = self.get_state(tag, attrs) if self.inraw or (state in [None, 'off'] and not self.mdstack): # fall back to default behavior attrs.pop('markdown', None) super().handle_starttag(tag, attrs) else: if 'p' in self.mdstack and tag in self.block_level_tags: # Close unclosed 'p' tag self.handle_endtag('p') self.mdstate.append(state) self.mdstack.append(tag) attrs['markdown'] = state self.treebuilder.start(tag, attrs) else: # Span level tag if self.inraw: super().handle_starttag(tag, attrs) else: text = self.get_starttag_text() if self.mdstate and self.mdstate[-1] == "off": self.handle_data(self.md.htmlStash.store(text)) else: self.handle_data(text) if tag in self.CDATA_CONTENT_ELEMENTS: # This is presumably a standalone tag in a code span (see #1036). self.clear_cdata_mode() def handle_endtag(self, tag): if tag in self.block_level_tags: if self.inraw: super().handle_endtag(tag) elif tag in self.mdstack: # Close element and any unclosed children while self.mdstack: item = self.mdstack.pop() self.mdstate.pop() self.treebuilder.end(item) if item == tag: break if not self.mdstack: # Last item in stack is closed. Stash it element = self.get_element() # Get last entry to see if it ends in newlines # If it is an element, assume there is no newlines item = self.cleandoc[-1] if self.cleandoc else '' # If we only have one newline before block element, add another if not item.endswith('\n\n') and item.endswith('\n'): self.cleandoc.append('\n') self.cleandoc.append(self.md.htmlStash.store(element)) self.cleandoc.append('\n\n') self.state = [] # Check if element has a tail if not blank_line_re.match( self.rawdata[self.line_offset + self.offset + len(self.get_endtag_text(tag)):]): # More content exists after `endtag`. self.intail = True else: # Treat orphan closing tag as a span level tag. text = self.get_endtag_text(tag) if self.mdstate and self.mdstate[-1] == "off": self.handle_data(self.md.htmlStash.store(text)) else: self.handle_data(text) else: # Span level tag if self.inraw: super().handle_endtag(tag) else: text = self.get_endtag_text(tag) if self.mdstate and self.mdstate[-1] == "off": self.handle_data(self.md.htmlStash.store(text)) else: self.handle_data(text) def handle_startendtag(self, tag, attrs): if tag in self.empty_tags: attrs = {key: value if value is not None else key for key, value in attrs} if "markdown" in attrs: attrs.pop('markdown') element = etree.Element(tag, attrs) data = etree.tostring(element, encoding='unicode', method='html') else: data = self.get_starttag_text() else: data = self.get_starttag_text() self.handle_empty_tag(data, is_block=self.md.is_block_level(tag)) def handle_data(self, data): if self.intail and '\n' in data: self.intail = False if self.inraw or not self.mdstack: super().handle_data(data) else: self.treebuilder.data(data) def handle_empty_tag(self, data, is_block): if self.inraw or not self.mdstack: super().handle_empty_tag(data, is_block) else: if self.at_line_start() and is_block: self.handle_data('\n' + self.md.htmlStash.store(data) + '\n\n') else: self.handle_data(self.md.htmlStash.store(data)) def parse_pi(self, i: int) -> int: if self.at_line_start() or self.intail or self.mdstack: # The same override exists in `HTMLExtractor` without the check # for `mdstack`. Therefore, use parent of `HTMLExtractor` instead. return super(HTMLExtractor, self).parse_pi(i) # This is not the beginning of a raw block so treat as plain data # and avoid consuming any tags which may follow (see #1066). self.handle_data('<?') return i + 2 def parse_html_declaration(self, i: int) -> int: if self.at_line_start() or self.intail or self.mdstack: # The same override exists in `HTMLExtractor` without the check # for `mdstack`. Therefore, use parent of `HTMLExtractor` instead. return super(HTMLExtractor, self).parse_html_declaration(i) # This is not the beginning of a raw block so treat as plain data # and avoid consuming any tags which may follow (see #1066). self.handle_data('<!') return i + 2 class HtmlBlockPreprocessor(Preprocessor): """Remove html blocks from the text and store them for later retrieval.""" def run(self, lines: list[str]) -> list[str]: source = '\n'.join(lines) parser = HTMLExtractorExtra(self.md) parser.feed(source) parser.close() return ''.join(parser.cleandoc).split('\n') class MarkdownInHtmlProcessor(BlockProcessor): """Process Markdown Inside HTML Blocks which have been stored in the `HtmlStash`.""" def test(self, parent: etree.Element, block: str) -> bool: # Always return True. `run` will return `False` it not a valid match. return True def parse_element_content(self, element: etree.Element) -> None: """ Recursively parse the text content of an `etree` Element as Markdown. Any block level elements generated from the Markdown will be inserted as children of the element in place of the text content. All `markdown` attributes are removed. For any elements in which Markdown parsing has been disabled, the text content of it and its children are wrapped in an `AtomicString`. """ md_attr = element.attrib.pop('markdown', 'off') if md_attr == 'block': # Parse content as block level # The order in which the different parts are parsed (text, children, tails) is important here as the # order of elements needs to be preserved. We can't be inserting items at a later point in the current # iteration as we don't want to do raw processing on elements created from parsing Markdown text (for # example). Therefore, the order of operations is children, tails, text. # Recursively parse existing children from raw HTML for child in list(element): self.parse_element_content(child) # Parse Markdown text in tail of children. Do this separate to avoid raw HTML parsing. # Save the position of each item to be inserted later in reverse. tails = [] for pos, child in enumerate(element): if child.tail: block = child.tail.rstrip('\n') child.tail = '' # Use a dummy placeholder element. dummy = etree.Element('div') self.parser.parseBlocks(dummy, block.split('\n\n')) children = list(dummy) children.reverse() tails.append((pos + 1, children)) # Insert the elements created from the tails in reverse. tails.reverse() for pos, tail in tails: for item in tail: element.insert(pos, item) # Parse Markdown text content. Do this last to avoid raw HTML parsing. if element.text: block = element.text.rstrip('\n') element.text = '' # Use a dummy placeholder element as the content needs to get inserted before existing children. dummy = etree.Element('div') self.parser.parseBlocks(dummy, block.split('\n\n')) children = list(dummy) children.reverse() for child in children: element.insert(0, child) elif md_attr == 'span': # Span level parsing will be handled by inline processors. # Walk children here to remove any `markdown` attributes. for child in list(element): self.parse_element_content(child) else: # Disable inline parsing for everything else if element.text is None: element.text = '' element.text = util.AtomicString(element.text) for child in list(element): self.parse_element_content(child) if child.tail: child.tail = util.AtomicString(child.tail) def run(self, parent: etree.Element, blocks: list[str]) -> bool: m = util.HTML_PLACEHOLDER_RE.match(blocks[0]) if m: index = int(m.group(1)) element = self.parser.md.htmlStash.rawHtmlBlocks[index] if isinstance(element, etree.Element): # We have a matched element. Process it. blocks.pop(0) self.parse_element_content(element) parent.append(element) # Cleanup stash. Replace element with empty string to avoid confusing postprocessor. self.parser.md.htmlStash.rawHtmlBlocks.pop(index) self.parser.md.htmlStash.rawHtmlBlocks.insert(index, '') # Confirm the match to the `blockparser`. return True # No match found. return False class MarkdownInHTMLPostprocessor(RawHtmlPostprocessor): def stash_to_string(self, text: str | etree.Element) -> str: """ Override default to handle any `etree` elements still in the stash. """ if isinstance(text, etree.Element): return self.md.serializer(text) else: return str(text) class MarkdownInHtmlExtension(Extension): """Add Markdown parsing in HTML to Markdown class.""" def extendMarkdown(self, md): """ Register extension instances. """ # Replace raw HTML preprocessor md.preprocessors.register(HtmlBlockPreprocessor(md), 'html_block', 20) # Add `blockprocessor` which handles the placeholders for `etree` elements md.parser.blockprocessors.register( MarkdownInHtmlProcessor(md.parser), 'markdown_block', 105 ) # Replace raw HTML postprocessor md.postprocessors.register(MarkdownInHTMLPostprocessor(md), 'raw_html', 30) def makeExtension(**kwargs): # pragma: no cover return MarkdownInHtmlExtension(**kwargs)