feat(goctl): Support gateway sample generation (#3049)

tools/goctl/util/templatex.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	goformat "go/format"
 	"io/ioutil"
+	"regexp"
 	"text/template"
 
 	"github.com/zeromicro/go-zero/tools/goctl/internal/errorx"
@@ -77,3 +78,18 @@ func (t *DefaultTemplate) Execute(data any) (*bytes.Buffer, error) {
 	buf.Write(formatOutput)
 	return buf, nil
 }
+
+// IsTemplateVariable returns true if the text is a template variable.
+// The text must start with a dot and be a valid template.
+func IsTemplateVariable(text string) bool {
+	match, _ := regexp.MatchString(`(?m)^{{(\.\w+)+}}$`, text)
+	return match
+}
+
+// TemplateVariable returns the variable name of the template.
+func TemplateVariable(text string) string {
+	if IsTemplateVariable(text) {
+		return text[3 : len(text)-2]
+	}
+	return ""
+}