fix: fix ExprSelector.Field method

Change-Id: I1f298b644e6fbeac5476bc4df5d9e8252c805151

Author: andeya

selector.go

@@ -44,6 +44,16 @@ func (f FieldSelector) Split() (paths []string, name string) {
 	return nil, s
 }
 
+// Parent returns the parent FieldSelector.
+func (f FieldSelector) Parent() (string, bool) {
+	s := string(f)
+	i := strings.LastIndex(s, FieldSeparator)
+	if i < 0 {
+		return "", false
+	}
+	return s[:i], true
+}
+
 // String returns string type value.
 func (f FieldSelector) String() string {
 	return string(f)
@@ -71,20 +81,21 @@ func (e ExprSelector) Name() string {
 	return s[atIdx+1:]
 }
 
-// Field returns the name of the field it belongs to.
+// Field returns the field selector it belongs to.
 func (e ExprSelector) Field() string {
 	s := string(e)
 	idx := strings.LastIndex(s, ExprNameSeparator)
 	if idx != -1 {
 		s = s[:idx]
 	}
-	idx = strings.LastIndex(s, FieldSeparator)
-	if idx != -1 {
-		return s[idx+1:]
-	}
 	return s
 }
 
+// ParentField returns the parent field selector it belongs to.
+func (e ExprSelector) ParentField() (string, bool) {
+	return FieldSelector(e.Field()).Parent()
+}
+
 // Split returns the field selector and the expression name.
 func (e ExprSelector) Split() (field FieldSelector, name string) {
 	s := string(e)

selector_test.go

@@ -0,0 +1,14 @@
+package tagexpr
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExprSelector(t *testing.T) {
+	es := ExprSelector("F1.Index")
+	field, ok := es.ParentField()
+	assert.True(t, ok)
+	assert.Equal(t, "F1", field)
+}

tagexpr_test.go

@@ -738,7 +738,7 @@ func TestNilField(t *testing.T) {
 		if !ok || !r {
 			t.Fatal(path, r)
 		}
-		t.Log(path, r)
+		t.Log("path:", path, "es:", es, "val:", r)
 		cnt++
 		return nil
 	})
@@ -795,6 +795,7 @@ func TestIssue3(t *testing.T) {
 	type C struct {
 		Id    string
 		Index int32 `vd:"$"`
+		P     *int  `vd:"$!=nil"`
 	}
 	type A struct {
 		F1 *C
@@ -804,6 +805,7 @@ func TestIssue3(t *testing.T) {
 		F1: &C{
 			Id:    "test",
 			Index: 1,
+			P:     new(int),
 		},
 	}
 	vm := New("vd")
@@ -813,6 +815,10 @@ func TestIssue3(t *testing.T) {
 			assert.Equal(t, float64(1), eval(), path)
 		case "F2.Index":
 			assert.Equal(t, nil, eval(), path)
+		case "F1.P":
+			assert.Equal(t, true, eval(), path)
+		case "F2.P":
+			assert.Equal(t, false, eval(), path)
 		}
 		return nil
 	})