| // Copyright 2021 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package site |
| |
| import ( |
| "bytes" |
| "regexp" |
| "strings" |
| |
| "github.com/yuin/goldmark" |
| "github.com/yuin/goldmark/ast" |
| "github.com/yuin/goldmark/extension" |
| "github.com/yuin/goldmark/parser" |
| "github.com/yuin/goldmark/renderer/html" |
| "github.com/yuin/goldmark/text" |
| "github.com/yuin/goldmark/util" |
| "golang.org/x/website/go.dev/cmd/internal/tmplfunc" |
| "golang.org/x/website/internal/backport/html/template" |
| ) |
| |
| // markdownToHTML converts markdown to HTML using the renderer and settings that Hugo uses. |
| func markdownToHTML(markdown string) (template.HTML, error) { |
| // parser.WithHeadingAttribute allows custom ids on headings. |
| // html.WithUnsafe allows use of raw HTML, which we need for tables. |
| md := goldmark.New( |
| goldmark.WithParserOptions( |
| parser.WithHeadingAttribute(), |
| parser.WithAutoHeadingID(), |
| parser.WithASTTransformers(util.Prioritized(mdTransformFunc(mdLink), 1)), |
| ), |
| goldmark.WithRendererOptions(html.WithUnsafe()), |
| goldmark.WithExtensions( |
| extension.NewTypographer(), |
| extension.NewLinkify( |
| extension.WithLinkifyAllowedProtocols([][]byte{[]byte("http"), []byte("https")}), |
| extension.WithLinkifyEmailRegexp(regexp.MustCompile(`[^\x00-\x{10FFFF}]`)), // impossible |
| ), |
| ), |
| ) |
| var buf bytes.Buffer |
| if err := md.Convert([]byte(markdown), &buf); err != nil { |
| return "", err |
| } |
| return template.HTML(buf.Bytes()), nil |
| } |
| |
| // mdTransformFunc is a func implementing parser.ASTTransformer. |
| type mdTransformFunc func(*ast.Document, text.Reader, parser.Context) |
| |
| func (f mdTransformFunc) Transform(node *ast.Document, reader text.Reader, pc parser.Context) { |
| f(node, reader, pc) |
| } |
| |
| // mdLink walks doc, adding rel=noreferrer target=_blank to non-relative links. |
| func mdLink(doc *ast.Document, _ text.Reader, _ parser.Context) { |
| mdLinkWalk(doc) |
| } |
| |
| func mdLinkWalk(n ast.Node) { |
| switch n := n.(type) { |
| case *ast.Link: |
| dest := string(n.Destination) |
| if strings.HasPrefix(dest, "https://") || strings.HasPrefix(dest, "http://") { |
| n.SetAttributeString("rel", []byte("noreferrer")) |
| n.SetAttributeString("target", []byte("_blank")) |
| } |
| return |
| case *ast.AutoLink: |
| // All autolinks are non-relative. |
| n.SetAttributeString("rel", []byte("noreferrer")) |
| n.SetAttributeString("target", []byte("_blank")) |
| return |
| } |
| |
| for child := n.FirstChild(); child != nil; child = child.NextSibling() { |
| mdLinkWalk(child) |
| } |
| } |
| |
| // markdownTemplateToHTML converts a markdown template to HTML, |
| // first applying the template execution engine and then interpreting |
| // the result as markdown to be converted to HTML. |
| // This is the same logic used by the Go web site. |
| func (site *Site) markdownTemplateToHTML(markdown string, p *page) (template.HTML, error) { |
| t := site.clone().New(p.file) |
| if err := tmplfunc.Parse(t, string(p.data)); err != nil { |
| return "", err |
| } |
| var buf bytes.Buffer |
| if err := t.Execute(&buf, p.params); err != nil { |
| return "", err |
| } |
| return markdownToHTML(buf.String()) |
| } |