chore: introduce HTMLBuilder (#37688)

modules/htmlutil/html.go

@@ -83,3 +83,34 @@ func HTMLPrintTag(w io.Writer, tag template.HTML, attrs map[string]string) (writ
 	written += n
 	return written, err
 }
+
+func EscapeString(s string) template.HTML {
+	return template.HTML(template.HTMLEscapeString(s))
+}
+
+type HTMLBuilder struct {
+	sb strings.Builder
+}
+
+func (b *HTMLBuilder) WriteString(s string) *HTMLBuilder {
+	b.sb.WriteString(template.HTMLEscapeString(s))
+	return b
+}
+
+func (b *HTMLBuilder) WriteHTML(s template.HTML) *HTMLBuilder {
+	b.sb.WriteString(string(s))
+	return b
+}
+
+func (b *HTMLBuilder) WriteFormat(fmt template.HTML, args ...any) *HTMLBuilder {
+	_, _ = HTMLPrintf(&b.sb, fmt, args...)
+	return b
+}
+
+func (b *HTMLBuilder) HTMLString() template.HTML {
+	return template.HTML(b.sb.String())
+}
+
+func (b *HTMLBuilder) String() string {
+	return b.sb.String()
+}

modules/htmlutil/html_test.go

@@ -22,3 +22,10 @@ func TestHTMLFormat(t *testing.T) {
 	assert.Equal(t, template.HTML("&lt;&gt;"), HTMLFormat("%s", template.URL("<>")))
 	assert.Equal(t, template.HTML("&amp;StringMethod &amp;StringMethod"), HTMLFormat("%s %s", testStringer{}, &testStringer{}))
 }
+
+func TestHTMLBuilder(t *testing.T) {
+	b := &HTMLBuilder{}
+	b.WriteString("<").WriteHTML("<hr>").WriteFormat("<span>%s%s</span>", ">", EscapeString(">"))
+	assert.Equal(t, "&lt;<hr><span>&gt;&gt;</span>", b.String())
+	assert.Equal(t, template.HTML("&lt;<hr><span>&gt;&gt;</span>"), b.HTMLString())
+}