goldmark-hashtag

goldmark-hashtag is an extension for the goldmark Markdown parser that adds support for tagging documents with #hashtags.

Demo: A web-based demonstration of the extension is available at https://abhinav.github.io/goldmark-hashtag/demo/.

Installation

go get go.abhg.dev/goldmark/hashtag@latest

Usage

To use goldmark-hashtag, import the hashtag package.

import "go.abhg.dev/goldmark/hashtag"

Then include the hashtag.Extender in the list of extensions you build your goldmark.Markdown with.

goldmark.New(
  goldmark.WithExtensions(
    &hashtag.Extender{},
  ),
  // ...
).Convert(src, out)

This alone has little effect besides adding <span class="hashtag">...</span> around hashtags in your Markdown document. You must supply a hashtag.Resolver to render hashtags as links.

Link resolution

Supply a hashtag.Resolver to the hashtag.Extender to render hashtags as links:

goldmark.New(
  goldmark.WithExtensions(
    &hashtag.Extender{
      Resolver: hashtagResolver,
    },
  ),
  // ...
).Convert(src, out)

Syntax

Hashtags must always begin with a "#". The characters that follow that depend on the variant you have chosen. goldmark-hashtag supports the following variants:

Default: Hashtags must begin with a letter, and may contain letters, numbers and any of the following symbols: /_-. goldmark-hashtag uses this variant if you do not specify one.
Obsidian: Hashtags can begin with and contain letters, numbers, emoji, and any of the following symbols: /_-, but must not contain only numbers.

You can specify the variant by setting the Variant property of the hashtag.Extender.

&hashtag.Extender{
  // ...
  Variant: hashtag.ObsidianVariant,
}

Inspection

To collect all hashtags from a Markdown document, use Goldmark's ast.Walk function after parsing the document.

For example, the following will populate the hashtags map with all hashtags found in the document.

markdown := goldmark.New(
  goldmark.WithExtensions(
    &hashtag.Extender{
      Resolver: hashtagResolver,
    },
  ),
  // ...
)

// Parse the Markdown document.
doc := markdown.Parser().Parse(text.NewReader(src))

// List the tags.
hashtags := make(map[string]struct{})
ast.Walk(doc, func(node ast.Node, enter bool) (ast.WalkStatus, error) {
  if n, ok := node.(*hashtag.Node); ok && enter {
    hashtags[string(n.Tag)] = struct{}{}
  }
  return ast.WalkContinue, nil
})

abhinav / goldmark-hashtag