feat(flatten): refactor code

Author: lvan100

.gitignore

@@ -30,3 +30,4 @@ go.work.sum
 # Editor/IDE
 .idea/
 .vscode/
+.gocache/

flatten/flat.go

@@ -99,7 +99,7 @@ func flattenValue(key string, val any, result map[string]string) {
 			subValue := v.Index(i).Interface()
 			flattenValue(subKey, subValue, result)
 		}
-	case reflect.Interface, reflect.Ptr:
+	case reflect.Interface, reflect.Pointer:
 		if v.IsNil() { // typed nil interface or pointer
 			result[key] = "<nil>"
 			return

flatten/path.go

@@ -17,6 +17,7 @@
 package flatten
 
 import (
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -32,6 +33,18 @@ const (
 	PathTypeIndex                 // A numeric index in a list.
 )
 
+// String returns the string representation of PathType.
+func (t PathType) String() string {
+	switch t {
+	case PathTypeKey:
+		return "key"
+	case PathTypeIndex:
+		return "index"
+	default:
+		return fmt.Sprintf("PathType(%d)", int8(t))
+	}
+}
+
 // Path represents a single segment in a parsed key path.
 // A path is composed of multiple Path elements that can be joined or split.
 // For example, "foo.bar[0]" parses into: