feat: check func type

cmd/decorator/compile.go

@@ -17,6 +17,7 @@ import (
 )
 
 const msgDecorPkgNotImported = "decorator used but package not imported (need add `import _ \"" + decoratorPackagePath + "\"`)"
+const msgCantUsedOnDecoratorFunc = `decorators cannot be used on decorators`
 
 func compile(args []string) error {
 	files := make([]string, 0, len(args))
@@ -113,13 +114,19 @@ func compile(args []string) error {
 				//x.Body.Rbrace = x.Body.Lbrace + token.Pos(ofs)
 				//log.Printf("fd.Body.Pos() %+v\n", fd.Body.Pos())
 				updated = true
-				name, ok := imp.importedPath(decoratorPackagePath)
+				pkgDecorName, ok := imp.importedPath(decoratorPackagePath)
 				if !ok {
 					logs.Error(msgDecorPkgNotImported, "\n\t",
 						friendlyIDEPosition(fset, doc.Pos()))
-				} else if name == "_" {
+				} else if pkgDecorName == "_" {
 					imp.pathObjMap[decoratorPackagePath].Name = nil // rewrite this package import way
 					imp.pathMap[decoratorPackagePath] = "decor"     // mark finished
+					pkgDecorName = "decor"
+				}
+
+				if funIsDecorator(fd, pkgDecorName) {
+					logs.Error(msgCantUsedOnDecoratorFunc, "\n\t",
+						friendlyIDEPosition(fset, fd.Pos()))
 				}
 
 				if x := decorX(decorName); x != "" {

cmd/decorator/lib_test.go

@@ -1,6 +1,10 @@
 package main
 
 import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
 	"testing"
 )
 
@@ -86,3 +90,41 @@ b:=2`,
 		}
 	}
 }
+
+func TestFunIsDecorator(t *testing.T) {
+	check := func(name, pkgName string) {
+		code := testGetCode(name, pkgName)
+		f, err := parser.ParseFile(token.NewFileSet(), "main.go", code, parser.ParseComments)
+		if err != nil || f == nil || len(f.Decls) == 0 {
+			t.Fatal("TestFunIsDecorator testGetCode parse error", err)
+		}
+		i := 0
+		for _, v := range f.Decls {
+			fd, ok := v.(*ast.FuncDecl)
+			if !ok {
+				continue
+			}
+			i++
+			if funIsDecorator(fd, pkgName) && fd.Name.Name != "isDecorator" {
+				t.Fatal(fd.Name.Name, "should not be a decorator function")
+			}
+		}
+		if i == 0 {
+			t.Fatal("f.Decls have type *ast.FuncDecl functions. but got 0")
+		}
+	}
+	check("", "decor")
+	check("dec", "dec")
+	check("a", "a")
+}
+
+func testGetCode(name, pkgName string) string {
+	return fmt.Sprintf(`
+package main
+import %s "github.com/dengsgo/go-decorator/decor"
+func isDecorator(ctx %s.Context) {}
+func notDecorator1(ctx %s.Context, a int) {}
+func notDecorator2(ctx %s.Contex) {}
+func notDecorator3(a int) {}
+`, name, pkgName, pkgName, pkgName)
+}