Function scanMarkdownRefs

internal/attachments/references.go:231–288

scanMarkdownRefs finds every place the markdown names one of the attached files.

(md string, attachmentArgs []attachmentArg)

// scanMarkdownRefs finds every place the markdown names one of the attached
// files.
func scanMarkdownRefs(md string, attachmentArgs []attachmentArg) ([]attachmentRef, error) {
	byPath, err := attachmentArgsByPath(attachmentArgs)
	if err != nil {
		return nil, err
	}

	src := []byte(md)
	doc := goldmark.New().Parser().Parse(text.NewReader(src))
	defs := linkReferenceDefinitions(doc, len(src))

	var refs []attachmentRef

	err = ast.Walk(doc, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
		if !entering {
			return ast.WalkContinue, nil
		}

		dest, isEmbed, ok := linkDestination(n)
		if !ok {
			return ast.WalkContinue, nil
		}
		idx, ok := attachmentArgForDestination(dest, byPath)
		if !ok {
			return ast.WalkContinue, nil
		}

		// The nearest block ancestor is what carries position information.
		var block ast.Node
		for p := n.Parent(); p != nil; p = p.Parent() {
			if p.Type() == ast.TypeBlock {
				block = p
				break
			}
		}
		_, hi, ok := blockRange(block, len(src))
		if !ok {
			return ast.WalkContinue, nil
		}

		if ranges, ok := inlineRanges(src, n, hi); ok {
			refs = append(refs, attachmentRef{attachmentArg: idx, isEmbed: isEmbed, ranges: ranges, block: block})
			return ast.WalkContinue, nil
		}

		// No destination beside the reference means a reference-style link. Every
		// definition carrying this destination is rewritten, since a node
		// records no label to tell them apart and a spare definition renders
		// nothing.
		if matches := defs[comparableDestination(dest)]; len(matches) > 0 {
			refs = append(refs, attachmentRef{attachmentArg: idx, isEmbed: isEmbed, defs: matches})
		}
		return ast.WalkContinue, nil
	})
	if err != nil {
		return nil, err
	}
	return refs, nil
}