trying a thing with neovim

testing a python remote plugin for quicker reStructuredText in Hugo

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600 words (about 3 minutes to read)

Tools / #neovim #python #hugo #rst #site

Published — Updated

But will it even work?

Oh right I need to :UpdateRemotePlugins first.

Test [PASSED]

It worked!

What did I just do?

I used a remote plugin in Neovim to transform my #rst into an HTML source document, simplifying Hugo's site-building duties.

I won't make you wait around for a proper post. [1] Hugo lets you use reStructuredText. But Hugo's way is slow and hard to customize. Not their fault. reStructuredText is not their focus. Still — why not format it ahead of time?

answer

Because it took a lot of work to figure this out? And most folks are perfectly happy with Markdown? And bloggers who prefer reStructuredText are probably using Pelican or Nikola?

Shush you.

The Implementation

Start with content/whatever/index.rst.txt.

Make sure Hugo won't track rst.txt files by explicitly adding an item the ignoreFiles config setting.

config.toml
ignoreFiles = ['\.rst\.txt$']

This way hugo server --navigateToChanged behaves how we expect.

Note

I tried setting ignoreFiles = ['\.rst$'] but as far as I could tell, Hugo ignored my request to ignore the file. Looks like I'm sticking with .rst.txt for now.

With the code down below in my Neovim python3 — that's python3 not python — rplugin folder, and remote plugins updated, I write index.rst.txt to disk.

The remote plugin transforms it to HTML, copying my YAML frontmatter as is. So what Hugo sees is updated HTML with frontmatter, and builds that into the site templates nice and quick.

The Code

~/.config/nvim/rplugin/python3/rstbuild_hugo.py
"""Give my reStructuredText posts in Hugo a little boost."""

import locale

import frontmatter
import pynvim
from docutils.core import publish_parts

locale.setlocale(locale.LC_ALL, "")


def determine_target(source: str) -> str:
    # Using an odd suffix so Hugo doesn't try to build the rst itself
    if not source.endswith(".rst.txt"):
        raise ValueError(f"Look at {source} more closely before transforming it.")

    return source.replace(".rst.txt", ".html")


@pynvim.plugin
class RSTBuildHugo:
    def __init__(self, nvim):
        self.nvim = nvim

    @pynvim.autocmd("BufWritePost", pattern="*.rst.txt", eval='expand("<afile>")')
    def convert_file(self, source_filename: str) -> None:
        target_path = determine_target(source_filename)
        post = frontmatter.load(source_filename)
        parts = publish_parts(source=post.content, writer_name="html")
        post.content = parts["body"]
        post.metadata["format"] = "rst"

        with open(target_path, "w") as out:
            out.write(frontmatter.dumps(post))

        self.nvim.out_write(f"Wrote {target_path}\n")

Lord knows this code ain't perfect. This post is its main test. Who knows what bugs and improvements will come later?

Note

You will, if you skim the Updates

If you grab a copy for your own nefarious plans — a similar template could get you fast Asciidoctor transforms as well — just remember a couple things:

  • make sure the Python you're using has the libraries needed; I listed my choices below
  • put it in the right folder; rplugin/python is for Python 2; rplugin/python3 is for Python 3
  • run :UpdateRemotePlugins and restart Neovim when you make changes to the plugin file

Libraries Used

  • Docutils of course, for transforming the reStructuredText
  • Docutils takes advantage of the fact that I have Pygments installed, for syntax highlighting
  • Python Frontmatter gives me a consistent tool for handling post frontmatter and content
  • pynvim is the bit that hooks it all into Neovim

Updates

2021-08-10

  • use the ignoreFiles config setting so Hugo stops watching .rst.txt files for changes
  • change BufWrite to BufWritePost so the transform happens after we write index.rst.txt
[1]I will update this post as I refine the approach, though. Makes more sense than adding little piecemeal posts as I go along.