Frontmatter support

[markusbkk]

Would be great if there was some way to add (custom) frontmatter to the rendering process.

[Dieter Eickstaedt]

Can you elaborate in what you would like to do with custom front matter data ? In terms of rendering that is.

[markusbkk]

Can you elaborate in what you would like to do with custom front matter data ? In terms of rendering that is.

Personally, in my specific case, I need it for things like title and synopsis.
I'm working on an alternative to Unix' man/mandoc. Would be great if there was a way to define a common template for this.
There's other ways to go about it too, of course. But I've always been a fan of using frontmatter to keep things organized and standardized.

[Dieter Eickstaedt]

Sounds reasonable but as far as I can see this looks like an extension to the underlying markdown parser.

[markusbkk]

Sounds reasonable but as far as I can see this looks like an extension to the underlying markdown parser.

I feared that.

Although I notice that glow has its own implementation (albeit one that only removes the frontmatter).

Maybe I can do something with this to implement my own preprocessor without depending on changes in glamour or goldmark.

[Dieter Eickstaedt]

@markusbkk I made some tests and adjusted my glamour fork as well as my local
glow

Essentially adding a FrontMatter YAML Parser to glamour and enabling a way to register a FrontMatter Callback.
As I am currently learning Go, I am not yet sure, if this is something I would PR in this stage. But serves as a POC I think.

// will be called once Frontmatter was parsed and converted to map
func (h Handler) HandleFrontmatter(frontmatter map[string]interface{}) {
	fmt.Printf("Hello Frontmatter %v", frontmatter)
}

// This is where the magic happens.
func glamourRender(m pagerModel, markdown string) (string, error) {
	if !config.GlamourEnabled {
		return markdown, nil
	}

	// initialize glamour
	var gs glamour.TermRendererOption
	if m.common.cfg.GlamourStyle == "auto" {
		gs = glamour.WithAutoStyle()
	} else {
		gs = glamour.WithStylePath(m.common.cfg.GlamourStyle)
	}

	width := max(0, min(int(m.common.cfg.GlamourMaxWidth), m.viewport.Width))
	r, err := glamour.NewTermRenderer(
		gs,
		glamour.WithWordWrap(width),
            
		glamour.WithFrontMatterHandler(Handler{}),
	)

[Dieter Eickstaedt]

Sounds reasonable but as far as I can see this looks like an extension to the underlying markdown parser.

I feared that.

Although I notice that glow has its own implementation (albeit one that only removes the frontmatter).

Maybe I can do something with this to implement my own preprocessor without depending on changes in glamour or goldmark.

Sure you could. As I wanted Frontmatter support for some scripts here as well, I thought about too. But this looked too much of a hack. So I decided to try to use the extension feature and add a new Parser. Because a Parser is the thing to do as it is a legit part of Markdown files in the wild