55 lines
1.8 KiB
Python
55 lines
1.8 KiB
Python
import base64
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import hashlib
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from functools import lru_cache
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from bs4 import BeautifulSoup # type: ignore
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from pygments import highlight as phighlight # type: ignore
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from pygments.formatters import HtmlFormatter # type: ignore
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from pygments.lexers import get_lexer_by_name # type: ignore
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from pygments.lexers import guess_lexer # type: ignore
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from app.config import CODE_HIGHLIGHTING_THEME
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_FORMATTER = HtmlFormatter(style=CODE_HIGHLIGHTING_THEME)
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HIGHLIGHT_CSS = _FORMATTER.get_style_defs()
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HIGHLIGHT_CSS_HASH = base64.b64encode(
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hashlib.sha256(HIGHLIGHT_CSS.encode()).digest()
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).decode()
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@lru_cache(256)
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def highlight(html: str) -> str:
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soup = BeautifulSoup(html, "html5lib")
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for code in soup.find_all("code"):
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if not code.parent.name == "pre":
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continue
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# Replace <br> tags with line breaks (Mastodon sends code like this)
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code_content = (
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code.encode_contents().decode().replace("<br>", "\n").replace("<br/>", "\n")
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)
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# If this comes from a microblog.pub instance we may have the language
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# in the class name
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if "class" in code.attrs and code.attrs["class"][0].startswith("language-"):
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try:
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lexer = get_lexer_by_name(
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code.attrs["class"][0].removeprefix("language-")
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)
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except Exception:
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lexer = guess_lexer(code_content)
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else:
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lexer = guess_lexer(code_content)
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# Replace the code with Pygment output
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# XXX: the HTML escaping causes issue with Python type annotations
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code_content = code_content.replace(") -> ", ") -> ")
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code.parent.replaceWith(
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BeautifulSoup(
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phighlight(code_content, lexer, _FORMATTER), "html5lib"
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).body.next
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)
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return soup.body.encode_contents().decode()
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