Converting Jupyter Notebook Cells to Pygments Syntax-Highlighted HTML

by Audrey M. Roy Greenfeld | Wed, Dec 25, 2024

## Understand the Problem Can a Jupyter notebook be converted to syntax-highlighted HTML easily with Pygments? Side note: Highlight.js is what Danny and Isaac use for syntax highlighting in FastHTML apps. I'll try that in another notebook later. I started this on a plane where I only had Pygments installed.

Devise a Plan

Carry Out Plan

from execnb.nbio import *
from fastcore.all import *
from fasthtml.common import *
from fasthtml.jupyter import *
from IPython.display import HTML, Markdown
from mistletoe import markdown, HTMLRenderer
from mistletoe.contrib.pygments_renderer import PygmentsRenderer
from nb2fasthtml.core import *
from pathlib import Path
import pygments
from pygments import highlight
from pygments.lexers import PythonLexer
from pygments.formatters import HtmlFormatter
from random import choice

nb = read_nb(Path("../nbs/2024-12-24-deck-the-halls.ipynb"))
nb.metadata

nb.cells

sources = L(nb.cells).itemgot('source')
sources

sources.map(Div)

code_cells = L(nb.cells).filter(lambda x: x.cell_type == 'code')
code_cells[:4]

code_cells[2]

Code Highlighting With Pygments

fm = HtmlFormatter(style='colorful')
pl = PythonLexer()

highlight("print('Hi')", lexer=pl, formatter=fm)

highlight(code_cells[2].source, lexer=pl, formatter=fm)

HTML(highlight(code_cells[2].source, lexer=pl, formatter=fm))

The previous cell should show colors but doesn't. Not sure how to show them here in this notebook.

def colorize(c): return highlight(c.source, lexer=pl, formatter=fm)

colorized = code_cells.map(colorize).map(NotStr)
colorized[:2]

def colorized_cells(cells): return cells.map(colorize).map(NotStr)

Formatter Styles

L(pygments.styles.STYLES.items())

L(pygments.styles.STYLES.items()).itemgot(1)

styles = L(pygments.styles.STYLES.items()).itemgot(1).itemgot(1)
styles

%%aip
Get a random style from that list

style = choice(styles)
style

CSS Styles

fm = HtmlFormatter(style='stata-dark')

fm.get_style_defs()[:100]

FastHTML app

app,rt = fast_app()

server = JupyUvi(app)

@rt
def index():
    nb = read_nb(Path("../nbs/2024-12-24-deck-the-halls.ipynb"))
    code_cells = L(nb.cells).filter(lambda x: x.cell_type == 'code')
    style = choice(styles)
    fm = HtmlFormatter(style=style)
    return (
        H1(f"Random style: {style}"),
        P("This page gets a random ",
            A("Pygments", href="https://pygments.org/"),
            " HtmlFormatter style and applies it to ",
            A("my Deck the Halls Jupyter notebook", href="https://nbsanity.com/static/a426287f3fbfc5a38c99291beadc77d3/2024-12-24-deck-the-halls.html")),
        Style(fm.get_style_defs()),
        Style(".highlight{border:1px solid gray;margin:10px;}"),
        Div(*colorized_cells(code_cells))
    )

Stopping the Server

if 'server' in globals(): server.stop()