Add mathjax

src/parsing/mathjax.go

@@ -0,0 +1,136 @@
+package parsing
+
+import (
+	gohtml "html"
+	"strings"
+
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// ----------------------
+// Parser and delimiters
+// ----------------------
+
+type mathjaxParser struct{}
+
+var _ parser.BlockParser = mathjaxParser{}
+
+func (s mathjaxParser) Trigger() []byte {
+	return []byte{'$'}
+}
+
+func (s mathjaxParser) Open(parent ast.Node, reader text.Reader, pc parser.Context) (ast.Node, parser.State) {
+	line, _ := reader.PeekLine()
+	lineStr := strings.TrimSpace(string(line))
+
+	if lineStr == "$$" {
+		return NewMathjax(), parser.NoChildren
+	} else {
+		return nil, parser.NoChildren
+	}
+}
+
+func (s mathjaxParser) Continue(node ast.Node, reader text.Reader, pc parser.Context) parser.State {
+	line, _ := reader.PeekLine()
+	lineStr := strings.TrimSpace(string(line))
+
+	if lineStr == "$$" {
+		reader.Advance(len(line))
+		return parser.Close
+	}
+
+	node.(*MathjaxNode).Source += string(line)
+	return parser.Continue | parser.NoChildren
+}
+
+func (s mathjaxParser) Close(node ast.Node, reader text.Reader, pc parser.Context) {}
+
+func (s mathjaxParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (s mathjaxParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+// ----------------------
+// AST node
+// ----------------------
+
+type MathjaxNode struct {
+	gast.BaseBlock
+	Source string
+}
+
+var _ gast.Node = &MathjaxNode{}
+
+func (n *MathjaxNode) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+var KindMathjax = gast.NewNodeKind("Mathjax")
+
+func (n *MathjaxNode) Kind() gast.NodeKind {
+	return KindMathjax
+}
+
+func NewMathjax() *MathjaxNode {
+	return &MathjaxNode{}
+}
+
+// ----------------------
+// Renderer
+// ----------------------
+
+type MathjaxHTMLRenderer struct {
+	html.Config
+}
+
+func NewMathjaxHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &MathjaxHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+func (r *MathjaxHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(KindMathjax, r.renderMathjax)
+}
+
+func (r *MathjaxHTMLRenderer) renderMathjax(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		w.WriteString("<div>\n")
+		w.WriteString("$$\n")
+		w.WriteString(gohtml.EscapeString(n.(*MathjaxNode).Source))
+		w.WriteString("$$\n")
+		w.WriteString("</div>\n")
+	}
+	return gast.WalkSkipChildren, nil
+}
+
+// ----------------------
+// Extension
+// ----------------------
+
+type MathjaxExtension struct {
+	Preview bool
+}
+
+func (e MathjaxExtension) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithBlockParsers(
+		util.Prioritized(mathjaxParser{}, 500),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewMathjaxHTMLRenderer(), 500),
+	))
+}

src/parsing/parsing.go

@@ -97,6 +97,7 @@ var previewMarkdown = goldmark.New(
 		EmbedExtension{
 			Preview: true,
 		},
+		MathjaxExtension{},
 		bTag{},
 	),
 )
@@ -105,6 +106,7 @@ var realMarkdown = goldmark.New(
 		extension.GFM,
 		SpoilerExtension{},
 		EmbedExtension{},
+		MathjaxExtension{},
 		bTag{},
 	),
 )

src/templates/src/editor.html

@@ -49,7 +49,7 @@
             <input type="submit" class="button ml2" name="preview" value="{{ .PreviewLabel }}" />
         </div>
 
-        <div class="post post-preview mv3">
+        <div class="post post-preview mv3 mathjax">
             <div id="preview" class="body contents"></div>
         </div>
 
@@ -111,6 +111,7 @@
     function updatePreview() {
         const previewHtml = parseMarkdown(tf.value);
         preview.innerHTML = previewHtml;
+        MathJax.typeset();
     }
 
     tf.addEventListener('input', () => {

src/templates/src/layouts/base.html

@@ -38,7 +38,7 @@
             {{ end }}
         }
     </style>
-    {{ block "extrahead" . }}{{ end }}
+
     <link rel="stylesheet" href="{{ statictheme .Theme "theme.css" }}" />
     <link rel="stylesheet" href="{{ .ProjectCSSUrl }}" />
     <link rel="apple-touch-icon" sizes="57x57" href="{{ static "apple-icon-57x57.png" }}">
@@ -58,6 +58,23 @@
     <meta name="msapplication-TileColor" content="#ffffff">
     <meta name="msapplication-TileImage" content="{{ static "ms-icon-144x144.png" }}">
     <meta name="theme-color" content="#ffffff">
+
+    {{ if .MathjaxEnabled }}
+        <script>
+            MathJax = {
+                tex: {
+                    inlineMath: [['$', '$']],
+                    displayMath: [['$$', '$$']],
+                },
+                svg: {
+                    fontCache: 'global',
+                }
+            };
+        </script>
+        <script async src="{{ static "mathjax.js" }}"></script>
+    {{ end }}
+
+    {{ block "extrahead" . }}{{ end }}
 </head>
 
 <body class="{{ join " " .BodyClasses }}">

src/templates/types.go

@@ -25,6 +25,7 @@ type BaseData struct {
 	IsProjectPage  bool
 	Header         Header
 	Footer         Footer
+	MathjaxEnabled bool
 }
 
 type Header struct {

src/website/forums.go

@@ -531,6 +531,7 @@ func ForumNewThread(c *RequestContext) ResponseData {
 
 	baseData := getBaseData(c)
 	baseData.Title = "Create New Thread"
+	baseData.MathjaxEnabled = true
 	// TODO(ben): Set breadcrumbs
 
 	var res ResponseData