343 lines
12 KiB
Python
343 lines
12 KiB
Python
"""
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richtext
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"""
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from typing import List, Tuple
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import re
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import urwid
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import unicodedata
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from .constants import PALETTE
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from bs4 import BeautifulSoup
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from bs4.element import NavigableString, Tag
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from urwidgets import TextEmbed, Hyperlink, parse_text
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from urwid.util import decompose_tagmarkup
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class ContentParser:
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def __init__(self):
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self.palette_names = []
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for p in PALETTE:
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self.palette_names.append(p[0])
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"""Parse a limited subset of HTML and create urwid widgets."""
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def html_to_widgets(self, html, recovery_attempt = False) -> List[urwid.Widget]:
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"""Convert html to urwid widgets"""
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widgets: List[urwid.Widget] = []
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html = unicodedata.normalize("NFKC", html)
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soup = BeautifulSoup(html.replace("'", "'"), "html.parser")
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first_tag = True
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for e in soup.body or soup:
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if isinstance(e, NavigableString):
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if first_tag and not recovery_attempt:
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# if our first "tag" is a navigable string
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# the HTML is out of spec, doesn't start with a tag,
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# we see this in content from Pixelfed servers.
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# attempt a fix by wrapping the HTML with <p></p>
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return self.html_to_widgets(f"<p>{html}</p>", recovery_attempt = True)
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else:
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continue
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else:
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first_tag = False
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name = e.name
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# First, look for a custom tag handler method in this class
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# If that fails, fall back to inline_tag_to_text handler
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method = getattr(self, "_" + name, self.inline_tag_to_text)
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markup = method(e) # either returns a Widget, or plain text
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if not isinstance(markup, urwid.Widget):
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# plaintext, so create a padded text widget
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txt = self.text_to_widget("", markup)
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markup = urwid.Padding(
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txt,
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align="left",
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width=("relative", 100),
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min_width=None,
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)
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widgets.append(markup)
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# separate top level widgets with a blank line
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widgets.append(urwid.Divider(" "))
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return widgets[:-1] # but suppress the last blank line
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def inline_tag_to_text(self, tag) -> Tuple:
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"""Convert html tag to plain text with tag as attributes recursively"""
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markups = self.process_inline_tag_children(tag)
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if not markups:
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return (tag.name, "")
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return (tag.name, markups)
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def process_inline_tag_children(self, tag) -> List:
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"""Recursively retrieve all children
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and convert to a list of markup text"""
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markups = []
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for child in tag.children:
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if isinstance(child, Tag):
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method = getattr(self, "_" + child.name, self.inline_tag_to_text)
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markup = method(child)
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markups.append(markup)
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else:
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markups.append(child)
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return markups
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def text_to_widget(self, attr, markup) -> TextEmbed:
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TRANSFORM = {
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# convert http[s] URLs to Hyperlink widgets for nesting in a TextEmbed widget
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re.compile(r'(^.+)\x03(.+$)'):
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lambda g: (len(g[1]), urwid.Filler(Hyperlink(g[2], attr, g[1]))),
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}
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markup_list = []
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for run in markup:
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if isinstance(run, tuple):
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txt, attr_list = decompose_tagmarkup(run)
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m = re.match(r'(^.+)\x03(.+$)', txt)
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if m:
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markup_list.append(parse_text(txt, TRANSFORM,
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lambda pattern, groups, span: TRANSFORM[pattern](groups)))
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else:
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markup_list.append(run)
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else:
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markup_list.append(run)
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return TextEmbed(markup_list)
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def process_block_tag_children(self, tag) -> List[urwid.Widget]:
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"""Recursively retrieve all children
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and convert to a list of widgets
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any inline tags containing text will be
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converted to Text widgets"""
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pre_widget_markups = []
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post_widget_markups = []
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child_widgets = []
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found_nested_widget = False
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for child in tag.children:
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if isinstance(child, Tag):
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# child is a nested tag; process using custom method
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# or default to inline_tag_to_text
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method = getattr(self, "_" + child.name, self.inline_tag_to_text)
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result = method(child)
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if isinstance(result, urwid.Widget):
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found_nested_widget = True
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child_widgets.append(result)
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else:
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if not found_nested_widget:
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pre_widget_markups.append(result)
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else:
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post_widget_markups.append(result)
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else:
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# child is text; append to the appropriate markup list
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if not found_nested_widget:
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pre_widget_markups.append(child)
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else:
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post_widget_markups.append(child)
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widget_list = []
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if len(pre_widget_markups):
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widget_list.append(self.text_to_widget(tag.name, pre_widget_markups))
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if len(child_widgets):
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widget_list += child_widgets
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if len(post_widget_markups):
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widget_list.append(self.text_to_widget(tag.name, post_widget_markups))
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return widget_list
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def get_urwid_attr_name(self, tag) -> str:
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"""Get the class name and translate to a
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name suitable for use as an urwid
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text attribute name"""
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if "class" in tag.attrs:
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clss = tag.attrs["class"]
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if len(clss) > 0:
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style_name = "class_" + "_".join(clss)
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# return the class name, only if we
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# find it as a defined palette name
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if style_name in self.palette_names:
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return style_name
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# fallback to returning the tag name
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return tag.name
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# Tag handlers start here.
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# Tags not explicitly listed are "supported" by
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# rendering as text.
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# Inline tags return a list of marked up text for urwid.Text
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# Block tags return urwid.Widget
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def basic_block_tag_handler(self, tag) -> urwid.Widget:
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"""default for block tags that need no special treatment"""
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return urwid.Pile(self.process_block_tag_children(tag))
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def _a(self, tag) -> Tuple:
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markups = self.process_inline_tag_children(tag)
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if not markups:
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return (tag.name, "")
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href = tag.attrs["href"]
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title, title_attrib = decompose_tagmarkup(markups)
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if href:
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# use \x03 (ETX) as a sentinel character
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# to signal a href following
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title += f"\x03{href}"
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# hashtag anchors have a class of "mention hashtag"
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# we'll return style "class_mention_hashtag"
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# in that case; see corresponding palette entry
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# in constants.py controlling hashtag highlighting
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return (self.get_urwid_attr_name(tag), title)
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def _blockquote(self, tag) -> urwid.Widget:
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widget_list = self.process_block_tag_children(tag)
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blockquote_widget = urwid.LineBox(
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urwid.Padding(
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urwid.Pile(widget_list),
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align="left",
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width=("relative", 100),
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min_width=None,
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left=1,
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right=1,
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),
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tlcorner="",
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tline="",
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lline="│",
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trcorner="",
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blcorner="",
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rline="",
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bline="",
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brcorner="",
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)
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return urwid.Pile([urwid.AttrMap(blockquote_widget, "blockquote")])
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def _br(self, tag) -> Tuple:
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return ("br", "\n")
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def _em(self, tag) -> Tuple:
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# to simplify the number of palette entries
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# translate EM to I (italic)
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markups = self.process_inline_tag_children(tag)
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if not markups:
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return ("i", "")
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# special case processing for bold and italic
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for parent in tag.parents:
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if parent.name == "b" or parent.name == "strong":
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return ("bi", markups)
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return ("i", markups)
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def _ol(self, tag) -> urwid.Widget:
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return self.list_widget(tag, ordered=True)
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def _pre(self, tag) -> urwid.Widget:
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# <PRE> tag spec says that text should not wrap,
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# but horizontal screen space is at a premium
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# and we have no horizontal scroll bar, so allow
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# wrapping.
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widget_list = [urwid.Divider(" ")]
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widget_list += self.process_block_tag_children(tag)
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pre_widget = urwid.Padding(
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urwid.Pile(widget_list),
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align="left",
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width=("relative", 100),
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min_width=None,
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left=1,
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right=1,
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)
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return urwid.Pile([urwid.AttrMap(pre_widget, "pre")])
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def _span(self, tag) -> Tuple:
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markups = self.process_inline_tag_children(tag)
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if not markups:
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return (tag.name, "")
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# span inherits its parent's class definition
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# unless it has a specific class definition
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# of its own
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if "class" in tag.attrs:
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style_name = self.get_urwid_attr_name(tag)
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if style_name != "span":
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# unique class name matches an entry in our palette
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return (style_name, markups)
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if tag.parent:
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return (self.get_urwid_attr_name(tag.parent), markups)
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else:
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# fallback
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return ("span", markups)
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def _strong(self, tag) -> Tuple:
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# to simplify the number of palette entries
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# translate STRONG to B (bold)
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markups = self.process_inline_tag_children(tag)
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if not markups:
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return ("b", "")
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# special case processing for bold and italic
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for parent in tag.parents:
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if parent.name == "i" or parent.name == "em":
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return ("bi", markups)
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return ("b", markups)
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def _ul(self, tag) -> urwid.Widget:
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return self.list_widget(tag, ordered=False)
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def list_widget(self, tag, ordered=False) -> urwid.Widget:
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"""common logic for ordered and unordered list rendering
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as urwid widgets"""
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widgets = []
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i = 1
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for li in tag.find_all("li", recursive=False):
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method = getattr(self, "_li", self.inline_tag_to_text)
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markup = method(li)
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if not isinstance(markup, urwid.Widget):
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if ordered:
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txt = self.text_to_widget("li", [str(i), ". ", markup])
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# 1. foo, 2. bar, etc.
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else:
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txt = self.text_to_widget("li", ["\N{bullet} ", markup])
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# * foo, * bar, etc.
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widgets.append(txt)
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else:
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if ordered:
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txt = self.text_to_widget("li", [str(i), ". "])
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else:
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txt = self.text_to_widget("li", ["\N{bullet} "])
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columns = urwid.Columns(
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[txt, ("weight", 9999, markup)], dividechars=1, min_width=3
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)
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widgets.append(columns)
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i += 1
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return urwid.Pile(widgets)
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# These tags are handled identically to others
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# the only difference being the tag name used for
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# urwid attribute mapping
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_b = _strong
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_div = basic_block_tag_handler
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_i = _em
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_li = basic_block_tag_handler
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# Glitch-soc and Pleroma allow <H1>...<H6> in content
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# Mastodon (PR #23913) does not; header tags are converted to <P><STRONG></STRONG></P>
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_h1 = _h2 = _h3 = _h4 = _h5 = _h6 = basic_block_tag_handler
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_p = basic_block_tag_handler
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