Implement --prettify parameter (only supports HTML for now).

[fvbommel]

This is similar to --minify, but has essentially the opposite effect: instead of making the output less readable it makes it more readable.

This uses github.com/yosssi/gohtml to perform the actual transformation.

Fixes #7190

---

The default configuration currently looks like this:

prettify:
  prettifyOutput: false
  disableHTML: false
  html:
    condense: false
    inlineTags:
      - a
      - code
      - em
      - span
      - strong
    inlineTagsMaxLength: 40

which is based on the defaults of gohtml.

I'm especially looking for feedback on whether the interface (parameter name and config syntax) are reasonable.

TODOs:

• For configuration stability the defaults should probably be hard-coded instead of taken from gohtml, right?
  • Currently the default configuration just imports the gohtml globals in the initializer.
• I haven't added the line wrapping configuration yet.
  • gohtml supports LineWrapColumn and LineWrapMaxSpillover.
• Documentation.

Stuff that may happen later:

• Support other media types (I'd prefer these to be separate PRs though)
  • At least JSON should be doable using encoding/json, I haven't looked into others.
• Add a Resources.Prettify pipeline function so it can be used from there too.
  • Less useful if only HTML is supported?

[CLAassistant]

All committers have signed the CLA.

[fvbommel]

Oh, sorry @nu8, I forgot to add that to the configuration syntax above. (I'll edit it in)

You can enable like this:

prettify:
  prettifyOutput: true

This is basically the same as how --minify can be enabled via the configuration file, but with "minify" replaced with "prettify".

[fvbommel]

I think it depends on how you structure your pages, but yes I've noticed that too if there are no tags on either end of the white space.

Like the first message says, this implementation uses github.com/yosssi/gohtml (as suggested in #7190), and it appears to mostly leave the "middle" of pure-text nodes alone. Mostly though, it seems to do a pretty good job.

If you know of a better HTML formatting lib written in Go though, feel free to suggest it. (I did look around a bit and this is definitely the most popular one I found at least)

Alternatively, you could raise this issue in https://github.com/yosssi/gohtml and/or submit a PR there.

[fvbommel]

Ah yes, that will also "break" it. 🤣

[bep]

Hey, thanks for this and sorry for the delay.

I need to wait with this. I looked into the gohtml package in relation with something else, and there are some bugs in there that means we cannot use this (my memory is a little hazy, but it's related to whitespace handling with text and span elements). I looked into fixing this upstream, but that looked hard ... I have been tinkering with my own html formatter Go package, which I think will get ready soonish ... will let you know.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. The resources of the Hugo team are limited, and so we are asking for your help.
If this is a bug and you can still reproduce this error on the master branch, please reply with all of the information you have about it in order to keep the issue open.
If this is a feature request, and you feel that it is still relevant and valuable, please tell us why.
This issue will automatically be closed in the near future if no further activity occurs. Thank you for all your contributions.

[jwflory]

Is there a chance of this work making it into a future release of Hugo?

[github-actions]

This PR has been automatically marked as stale because it has not had recent activity. The resources of the Hugo team are limited, and so we are asking for your help.
Please check https://github.com/gohugoio/hugo/blob/master/CONTRIBUTING.md#code-contribution and verify that this code contribution fits with the description. If yes, tell is in a comment.
This PR will automatically be closed in the near future if no further activity occurs. Thank you for all your contributions.

[BBaoVanC]

Please don't close this, I would love this feature!

[hiAndrewQuinn]

I'd be interested in this too. Commenting to keep it alive.

[mjp4]

I too would love to see this get in.

[awfulwoman]

Just to say that I was looking for exactly this in Hugo! Would love to see it integrated. ❤️