Squashed 'backend/goldmark/' content from commit 379bf24

git-subtree-dir: backend/goldmark
git-subtree-split: 379bf24a47e6ef07f34d7536aead86d8792ac300

extension/cjk.go

@@ -0,0 +1,72 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer/html"
+)
+
+// A CJKOption sets options for CJK support mostly for HTML based renderers.
+type CJKOption func(*cjk)
+
+// A EastAsianLineBreaks is a style of east asian line breaks.
+type EastAsianLineBreaks int
+
+const (
+	//EastAsianLineBreaksNone renders line breaks as it is.
+	EastAsianLineBreaksNone EastAsianLineBreaks = iota
+	// EastAsianLineBreaksSimple is a style where soft line breaks are ignored
+	// if both sides of the break are east asian wide characters.
+	EastAsianLineBreaksSimple
+	// EastAsianLineBreaksCSS3Draft is a style where soft line breaks are ignored
+	// even if only one side of the break is an east asian wide character.
+	EastAsianLineBreaksCSS3Draft
+)
+
+// WithEastAsianLineBreaks is a functional option that indicates whether softline breaks
+// between east asian wide characters should be ignored.
+// style defauts to [EastAsianLineBreaksSimple] .
+func WithEastAsianLineBreaks(style ...EastAsianLineBreaks) CJKOption {
+	return func(c *cjk) {
+		if len(style) == 0 {
+			c.EastAsianLineBreaks = EastAsianLineBreaksSimple
+			return
+		}
+		c.EastAsianLineBreaks = style[0]
+	}
+}
+
+// WithEscapedSpace is a functional option that indicates that a '\' escaped half-space(0x20) should not be rendered.
+func WithEscapedSpace() CJKOption {
+	return func(c *cjk) {
+		c.EscapedSpace = true
+	}
+}
+
+type cjk struct {
+	EastAsianLineBreaks EastAsianLineBreaks
+	EscapedSpace        bool
+}
+
+// CJK is a goldmark extension that provides functionalities for CJK languages.
+var CJK = NewCJK(WithEastAsianLineBreaks(), WithEscapedSpace())
+
+// NewCJK returns a new extension with given options.
+func NewCJK(opts ...CJKOption) goldmark.Extender {
+	e := &cjk{
+		EastAsianLineBreaks: EastAsianLineBreaksNone,
+	}
+	for _, opt := range opts {
+		opt(e)
+	}
+	return e
+}
+
+func (e *cjk) Extend(m goldmark.Markdown) {
+	m.Renderer().AddOptions(html.WithEastAsianLineBreaks(
+		html.EastAsianLineBreaks(e.EastAsianLineBreaks)))
+	if e.EscapedSpace {
+		m.Renderer().AddOptions(html.WithWriter(html.NewWriter(html.WithEscapedSpace())))
+		m.Parser().AddOptions(parser.WithEscapedSpace())
+	}
+}