/
md2html.go
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/
md2html.go
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//
// md2html :: md2html.go
//
// Copyright (c) 2020-2024 Akinori Hattori <hattya@gmail.com>
//
// SPDX-License-Identifier: MIT
//
package main
import (
"bufio"
"flag"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"github.com/yuin/goldmark"
"github.com/yuin/goldmark-emoji"
"github.com/yuin/goldmark/extension"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/renderer/html"
"github.com/yuin/goldmark/text"
)
const (
highlightJS = "https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@11/build"
mathJax = "https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"
mermaid = "https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.esm.min.mjs"
)
var base string
var (
diag = flag.Bool("diag", false, "use Mermaid")
embed = flag.Bool("embed", false, "embed local files")
hl = flag.Bool("hl", true, "use highlight.js")
hllang = csv{}
hlstyle = flag.String("hlstyle", "github", "highlight.js style")
lang = flag.String("lang", "en", "HTML lang attribute")
math = flag.Bool("m", false, "use MathJax")
style = flag.String("style", "", "style sheet")
title = flag.String("title", "", "document title")
)
func init() {
var err error
if base, err = os.Getwd(); err != nil {
exit(err)
}
flag.Var(&hllang, "hllang", "comma separated list of highlight.js languages")
}
func main() {
flag.Parse()
src, err := open(0)
if err != nil {
exit(err)
}
defer src.Close()
dst, err := open(1)
if err != nil {
exit(err)
}
defer dst.Close()
exit(convert(src, dst))
}
func open(fd int) (f *os.File, err error) {
switch fd {
case 0:
if name := flag.Arg(fd); name != "" {
base = filepath.Dir(name)
return os.Open(name)
}
f = os.Stdin
case 1:
if name := flag.Arg(fd); name != "" {
return os.Create(name)
}
f = os.Stdout
default:
err = os.ErrInvalid
}
return
}
func exit(err error) {
if err != nil {
fmt.Fprintf(os.Stderr, "%v: %v\n", os.Args[0], err)
os.Exit(1)
}
os.Exit(0)
}
func convert(r io.Reader, w io.Writer) (err error) {
md := goldmark.New(
goldmark.WithParserOptions(
parser.WithAutoHeadingID(),
parser.WithHeadingAttribute(),
),
goldmark.WithRendererOptions(
html.WithUnsafe(),
),
goldmark.WithExtensions(
extension.NewCJK(
extension.WithEastAsianLineBreaks(extension.EastAsianLineBreaksCSS3Draft),
extension.WithEscapedSpace(),
),
extension.GFM,
emoji.Emoji,
new(md2html),
),
)
src, err := readAll(r)
if err != nil {
return
}
doc := md.Parser().Parse(text.NewReader(src))
fmt.Fprintln(w, `<!DOCTYPE html>`)
fmt.Fprintf(w, "<html lang=\"%s\">\n", *lang)
fmt.Fprintln(w, `<head>`)
fmt.Fprintln(w, `<meta charset="UTF-8">`)
fmt.Fprintf(w, "<title>%s</title>\n", *title)
if *style != "" {
if *embed {
var f *os.File
if f, err = os.Open(filepath.Join(base, *style)); err != nil {
return
}
defer f.Close()
var b []byte
if b, err = readAll(f); err != nil {
return
}
fmt.Fprintln(w, `<style>`)
w.Write(b)
fmt.Fprintln(w, `</style>`)
} else {
fmt.Fprintf(w, "<link rel=\"stylesheet\" href=\"%s\">\n", *style)
}
}
// highlight.js
if *hl && *hlstyle != "" {
fmt.Fprintf(w, "<link rel=\"stylesheet\" href=\"%s/styles/%s.min.css\">\n", highlightJS, *hlstyle)
fmt.Fprintf(w, "<script src=\"%s/highlight.min.js\"></script>\n", highlightJS)
for _, lang := range hllang {
fmt.Fprintf(w, "<script src=\"%s/languages/%s.min.js\"></script>\n", highlightJS, lang)
}
fmt.Fprintln(w, `<script>hljs.highlightAll();</script>`)
}
// MathJax
if *math {
fmt.Fprintln(w, `<script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>`)
fmt.Fprintf(w, "<script id=\"MathJax-script\" async src=\"%s\"></script>\n", mathJax)
}
// Mermaid
if *diag {
fmt.Fprintln(w, `<script type="module">`)
fmt.Fprintf(w, "import mermaid from '%s';\n", mermaid)
fmt.Fprintln(w, `mermaid.initialize({ startOnLoad: true });`)
fmt.Fprintln(w, `</script>`)
}
fmt.Fprintln(w, `</head>`)
fmt.Fprintln(w, `<body>`)
fmt.Fprintln(w, `<article class="markdown">`)
if err = md.Renderer().Render(w, src, doc); err != nil {
return
}
fmt.Fprintln(w, `</article>`)
fmt.Fprintln(w, `</body>`)
fmt.Fprintln(w, `</html>`)
return
}
func readAll(r io.Reader) ([]byte, error) {
var buf []byte
br := bufio.NewReader(r)
for {
l, err := br.ReadBytes('\n')
// convert CRLF $B"*(B LF
if len(l) > 1 && l[len(l)-2] == '\r' {
l = l[:len(l)-1]
l[len(l)-1] = '\n'
}
buf = append(buf, l...)
if err != nil {
if err == io.EOF {
return buf, nil
}
return nil, err
}
}
}
type csv []string
func (csv *csv) Set(s string) error {
for _, v := range strings.Split(s, ",") {
*csv = append(*csv, strings.TrimSpace(v))
}
return nil
}
func (csv *csv) Get() interface{} { return []string(*csv) }
func (csv *csv) String() string { return strings.Join(*csv, ",") }