hmn/src/parsing/mathjax.go

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2021-06-20 19:06:22 +00:00
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),
))
}