58 lines
1.3 KiB
Go
58 lines
1.3 KiB
Go
package main
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import (
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"strings"
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"github.com/yuin/goldmark"
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"github.com/yuin/goldmark/ast"
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"github.com/yuin/goldmark/parser"
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"github.com/yuin/goldmark/text"
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"github.com/yuin/goldmark/util"
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)
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type extLinksTransformer struct{}
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func (extLinksTransformer) Transform(doc *ast.Document, reader text.Reader, pc parser.Context) {
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ast.Walk(doc, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
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if !entering {
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return ast.WalkContinue, nil
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}
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link, ok := n.(*ast.Link)
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if !ok {
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return ast.WalkContinue, nil
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}
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if isExternalURL(string(link.Destination)) {
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link.SetAttribute([]byte("target"), []byte("_blank"))
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link.SetAttribute([]byte("rel"), []byte("noopener noreferrer"))
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}
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return ast.WalkContinue, nil
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})
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}
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func isExternalURL(dest string) bool {
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if strings.HasPrefix(dest, "//") {
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return true
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}
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i := strings.Index(dest, ":")
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if i <= 0 {
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return false
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}
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for _, c := range dest[:i] {
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if !(c >= 'a' && c <= 'z') && !(c >= 'A' && c <= 'Z') &&
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!(c >= '0' && c <= '9') && c != '+' && c != '-' && c != '.' {
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return false
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}
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}
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return true
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}
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type extLinksExt struct{}
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func newExtLinksExt() goldmark.Extender { return &extLinksExt{} }
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func (e *extLinksExt) Extend(m goldmark.Markdown) {
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m.Parser().AddOptions(parser.WithASTTransformers(
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util.Prioritized(extLinksTransformer{}, 999),
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))
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}
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