1 files changed, 107 insertions, 0 deletions
diff --git a/modules/markup/markdown/math/math.go b/modules/markup/markdown/math/math.go
new file mode 100644
index 00000000..8a507535
--- /dev/null
+++ b/modules/markup/markdown/math/math.go
@@ -0,0 +1,107 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package math
+
+import (
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/util"
+)
+
+// Extension is a math extension
+type Extension struct {
+	enabled           bool
+	parseDollarInline bool
+	parseDollarBlock  bool
+}
+
+// Option is the interface Options should implement
+type Option interface {
+	SetOption(e *Extension)
+}
+
+type extensionFunc func(e *Extension)
+
+func (fn extensionFunc) SetOption(e *Extension) {
+	fn(e)
+}
+
+// Enabled enables or disables this extension
+func Enabled(enable ...bool) Option {
+	value := true
+	if len(enable) > 0 {
+		value = enable[0]
+	}
+	return extensionFunc(func(e *Extension) {
+		e.enabled = value
+	})
+}
+
+// WithInlineDollarParser enables or disables the parsing of $...$
+func WithInlineDollarParser(enable ...bool) Option {
+	value := true
+	if len(enable) > 0 {
+		value = enable[0]
+	}
+	return extensionFunc(func(e *Extension) {
+		e.parseDollarInline = value
+	})
+}
+
+// WithBlockDollarParser enables or disables the parsing of $$...$$
+func WithBlockDollarParser(enable ...bool) Option {
+	value := true
+	if len(enable) > 0 {
+		value = enable[0]
+	}
+	return extensionFunc(func(e *Extension) {
+		e.parseDollarBlock = value
+	})
+}
+
+// Math represents a math extension with default rendered delimiters
+var Math = &Extension{
+	enabled:           true,
+	parseDollarBlock:  true,
+	parseDollarInline: true,
+}
+
+// NewExtension creates a new math extension with the provided options
+func NewExtension(opts ...Option) *Extension {
+	r := &Extension{
+		enabled:           true,
+		parseDollarBlock:  true,
+		parseDollarInline: true,
+	}
+
+	for _, o := range opts {
+		o.SetOption(r)
+	}
+	return r
+}
+
+// Extend extends goldmark with our parsers and renderers
+func (e *Extension) Extend(m goldmark.Markdown) {
+	if !e.enabled {
+		return
+	}
+
+	m.Parser().AddOptions(parser.WithBlockParsers(
+		util.Prioritized(NewBlockParser(e.parseDollarBlock), 701),
+	))
+
+	inlines := []util.PrioritizedValue{
+		util.Prioritized(NewInlineBracketParser(), 501),
+	}
+	if e.parseDollarInline {
+		inlines = append(inlines, util.Prioritized(NewInlineDollarParser(), 501))
+	}
+	m.Parser().AddOptions(parser.WithInlineParsers(inlines...))
+
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewBlockRenderer(), 501),
+		util.Prioritized(NewInlineRenderer(), 502),
+	))
+}