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Monorepo for Tangled tangled.org
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import ( "bytes"
"github.com/gohugoio/hugo-goldmark-extensions/passthrough" "github.com/yuin/goldmark" "github.com/yuin/goldmark/ast" "github.com/yuin/goldmark/renderer" "github.com/yuin/goldmark/util")
// MathExt renders LaTeX math for client-side typesetting.//// Detection is delegated to the Hugo passthrough extension, which correctly// handles single-line "$$...$$" display blocks and protects markdown inside// math (e.g. "$a_1$" is not emphasis).// We override passthrough's verbatim renderers so each span is wrapped in// <span class="math inline|display"> carrying the raw LaTeX with MathJax// \( \) / \[ \] delimiters. MathJax (loaded on demand in layouts/base.html)// typesets only these spans, so surrounding prose is never scanned — which is// what keeps a stray "$" in body text from being interpreted as math.var MathExt = &mathExt{}
type mathExt struct{}
func (e *mathExt) Extend(m goldmark.Markdown) { // Installs the passthrough parsers (and its own verbatim renderers, which // we override below). passthrough.New(passthrough.Config{ InlineDelimiters: []passthrough.Delimiters{ {Open: "$", Close: "$"}, {Open: `\(`, Close: `\)`}, }, BlockDelimiters: []passthrough.Delimiters{ {Open: "$$", Close: "$$"}, {Open: `\[`, Close: `\]`}, }, }).Extend(m)
// Higher priority than passthrough's default renderers (priority 100), so // ours win for the passthrough node kinds. m.Renderer().AddOptions(renderer.WithNodeRenderers( util.Prioritized(&mathRenderer{}, 1), ))}
type mathRenderer struct{}
func (r *mathRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) { reg.Register(passthrough.KindPassthroughInline, r.renderInline) reg.Register(passthrough.KindPassthroughBlock, r.renderBlock)}
func (r *mathRenderer) renderInline(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) { if !entering { return ast.WalkSkipChildren, nil } node := n.(*passthrough.PassthroughInline) open, closing := node.Delimiters.Open, node.Delimiters.Close raw := node.Segment.Value(source) inner := raw[len(open) : len(raw)-len(closing)]
// Currency guard for "$"-delimited inline math (Pandoc's rules): a "$...$" // run is not math if the inner text is empty or space-padded, or if the // closing "$" is immediately followed by a digit (e.g. "$5 and $10"). In // those cases emit the run verbatim so MathJax never sees it. if open == "$" { var after byte if node.Segment.Stop < len(source) { after = source[node.Segment.Stop] } if len(inner) == 0 || inner[0] == ' ' || inner[len(inner)-1] == ' ' || isASCIIDigit(after) { w.Write(raw) return ast.WalkSkipChildren, nil } }
w.WriteString(`<span class="math inline">\(`) w.Write(util.EscapeHTML(inner)) w.WriteString(`\)</span>`) return ast.WalkSkipChildren, nil}
func (r *mathRenderer) renderBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) { if !entering { return ast.WalkSkipChildren, nil } node := n.(*passthrough.PassthroughBlock) open, closing := node.Delimiters.Open, node.Delimiters.Close
var buf bytes.Buffer for i := 0; i < node.Lines().Len(); i++ { seg := node.Lines().At(i) buf.Write(seg.Value(source)) }
inner := bytes.TrimSpace(buf.Bytes()) inner = bytes.TrimPrefix(inner, []byte(open)) inner = bytes.TrimSuffix(inner, []byte(closing)) inner = bytes.TrimSpace(inner)
w.WriteString(`<p><span class="math display">\[`) w.Write(util.EscapeHTML(inner)) w.WriteString(`\]</span></p>`) return ast.WalkSkipChildren, nil}
func isASCIIDigit(b byte) bool { return b >= '0' && b <= '9' }