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annotate wdown.go @ 8:4a25b534c81c javascript-experiment

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Add v8 engine and include katex
author Jonatan Werpers <jonatan@werpers.com>
date Wed, 17 Jun 2020 21:43:52 +0200
parents a5aa39557726
children
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1 package main
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2
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3 import (
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4 "bytes"
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5 "flag"
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6 "fmt"
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7 "io/ioutil"
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8 "log"
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9 "os"
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10
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11 "github.com/cbroglie/mustache"
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12 "github.com/yuin/goldmark"
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13 highlighting "github.com/yuin/goldmark-highlighting"
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14 meta "github.com/yuin/goldmark-meta"
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15 "github.com/yuin/goldmark/extension"
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16 "github.com/yuin/goldmark/parser"
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17 "rogchap.com/v8go"
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18 )
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19
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20 func main() {
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21 var templateFilename string
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22
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23 flag.StringVar(&templateFilename, "tmpl", "", "Template file to render the html inside. The content of the markdown file will replace the placeholder {{content}}.")
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24
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25 flag.Parse()
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26
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27 if flag.NArg() < 1 {
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28 fmt.Println("Please provide a markdown file for parsing.")
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29 os.Exit(1)
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30 }
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31
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32 var useTemplate = false
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33 if templateFilename != "" {
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34 useTemplate = true
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35 }
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36
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37 tmpl, err := mustache.ParseFile(templateFilename)
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38 if err != nil {
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39 log.Fatal(err)
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40 }
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41
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42 source, err := ioutil.ReadFile(flag.Arg(0))
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44 if err != nil {
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45 log.Fatal(err)
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46 }
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47
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48 md := goldmark.New(
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49 goldmark.WithExtensions(
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50 extension.GFM,
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51 highlighting.Highlighting,
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52 meta.Meta,
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53 ),
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54 goldmark.WithParserOptions(
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55 parser.WithAutoHeadingID(),
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56 ),
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57 )
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58
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59 var htmlContent bytes.Buffer
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60 parserContext := parser.NewContext()
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61 err = md.Convert(source, &htmlContent, parser.WithContext(parserContext))
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62 if err != nil {
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63 log.Fatal(err)
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64 }
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66 if useTemplate {
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67 templateVars := meta.Get(parserContext)
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68 templateVars["content"] = htmlContent.String()
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69
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70 err := tmpl.FRender(os.Stdout, templateVars)
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71 if err != nil {
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72 log.Fatal(err)
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73 }
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74 } else {
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75 fmt.Print(htmlContent)
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76 }
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78 katexFormula := "c = \\pm\\sqrt{a^2 + b^2} = \\pm x^2"
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79 katexRenderOptions := `{
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80 throwOnError: false,
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81 displayMode: true,
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82 }
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83 `
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84 ctx, _ := v8go.NewContext(nil) // creates a new V8 context with a new Isolate aka VM
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85 ctx.RunScript(katexSrc(), "katex/katex.js")
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86 ctx.RunScript("const katexFormula = String.raw`"+katexFormula+"`", "main.js") // executes a script on the global context
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87 ctx.RunScript("const mathHtml = katex.renderToString(katexFormula,"+katexRenderOptions+")", "main.js") // any functions previously added to the context can be called
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88 mathHtml, _ := ctx.RunScript("mathHtml", "value.js") // return a value in JavaScript back to Go
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89 fmt.Println(mathHtml)
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90 }
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91
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92 func katexSrc() string {
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93 katexBytes, err := ioutil.ReadFile("katex/katex.js")
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94 if err != nil {
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95 log.Fatal(err)
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96 }
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97
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98 return string(katexBytes)
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99 }