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package main
// example for https://blog.kowalczyk.info/article/cxn3/advanced-markdown-processing-in-go.html
import (
"fmt"
"github.com/gomarkdown/markdown"
"github.com/gomarkdown/markdown/ast"
"github.com/gomarkdown/markdown/html"
"github.com/gomarkdown/markdown/parser"
"strings"
)
func modifyAst(doc ast.Node) ast.Node {
ast.WalkFunc(doc, func(node ast.Node, entering bool) ast.WalkStatus {
if img, ok := node.(*ast.Image); ok && entering {
attr := img.Attribute
if attr == nil {
attr = &ast.Attribute{}
}
// TODO: might be duplicate
attr.Classes = append(attr.Classes, []byte("blog-img"))
img.Attribute = attr
}
if link, ok := node.(*ast.Link); ok && entering {
isExternalURI := func(uri string) bool {
return (strings.HasPrefix(uri, "https://") || strings.HasPrefix(uri, "http://")) && !strings.Contains(uri, "blog.kowalczyk.info")
}
if isExternalURI(string(link.Destination)) {
link.AdditionalAttributes = append(link.AdditionalAttributes, `target="_blank"`)
}
}
return ast.GoToNext
})
return doc
}
var mds = `[link](http://example.com)`
func modifyAstExample() {
md := []byte(mds)
extensions := parser.CommonExtensions
p := parser.NewWithExtensions(extensions)
doc := p.Parse(md)
doc = modifyAst(doc)
htmlFlags := html.CommonFlags
opts := html.RendererOptions{Flags: htmlFlags}
renderer := html.NewRenderer(opts)
html := markdown.Render(doc, renderer)
fmt.Printf("-- Markdown:\n%s\n\n--- HTML:\n%s\n", md, html)
}
func main() {
modifyAstExample()
}
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