zero checks + more tests

explorer.go

@@ -3,6 +3,7 @@ package structexplorer
 import (
 	"fmt"
 	"log/slog"
+	"reflect"
 )
 
 type objectAccess struct {
@@ -128,3 +129,24 @@ func (e *explorer) buildIndexData() indexData {
 	}
 	return b.data
 }
+
+func canExplore(v any) bool {
+	rt := reflect.TypeOf(v)
+	if rt.Kind() == reflect.Interface || rt.Kind() == reflect.Pointer {
+		rv := reflect.ValueOf(v)
+		if rv.IsZero() {
+			return false
+		}
+		rt = rt.Elem()
+	}
+	if rt.Kind() == reflect.Struct {
+		return true
+	}
+	if rt.Kind() == reflect.Slice {
+		return true
+	}
+	if rt.Kind() == reflect.Map {
+		return true
+	}
+	return false
+}

explorer_test.go

@@ -45,3 +45,10 @@ func TestExplorerTable(t *testing.T) {
 		t.Errorf("got [%v]:%T want [%v]:%T", got, got, want, want)
 	}
 }
+
+func TestCanExplorePointerNil(t *testing.T) {
+	var w *time.Time
+	if got, want := canExplore(w), false; got != want {
+		t.Errorf("got [%[1]v:%[1]T] want [%[2]v:%[2]T]", got, want)
+	}
+}

field.go

@@ -88,6 +88,7 @@ func (f fieldAccess) withPaddingTo(size int) fieldAccess {
 	return f
 }
 
+// pre: canExplore(v)
 func newFields(v any) []fieldAccess {
 	list := []fieldAccess{}
 	if v == nil {
@@ -96,7 +97,8 @@ func newFields(v any) []fieldAccess {
 	var rt reflect.Type
 	rv := reflect.ValueOf(v)
 	if rv.Kind() == reflect.Interface || rv.Kind() == reflect.Pointer {
-		rt = rv.Elem().Type()
+		elm := rv.Elem()
+		rt = elm.Type()
 	} else {
 		rt = reflect.TypeOf(v)
 	}
@@ -202,6 +204,9 @@ func printString(v any) string {
 		}
 		return fmt.Sprintf("*%f", rv.Float())
 	case reflect.Value:
+		if !tv.IsValid() || tv.IsZero() {
+			return "~nil"
+		}
 		return "~" + printString(tv.Interface())
 	}
 	// can return string?
@@ -218,6 +223,12 @@ func printString(v any) string {
 		rv := reflect.ValueOf(v)
 		return fmt.Sprintf("%T (%d)", v, rv.Len())
 	}
+	if rt.Kind() == reflect.Pointer {
+		rv := reflect.ValueOf(v).Elem()
+		if !rv.IsValid() || rv.IsZero() {
+			return "nil"
+		}
+	}
 	return ellipsis(fmt.Sprintf("%[1]T", v))
 }
 
@@ -228,26 +239,6 @@ func ellipsis(s string) string {
 	return s
 }
 
-func canExplore(v any) bool {
-	if v == nil {
-		return false
-	}
-	rt := reflect.TypeOf(v)
-	if rt.Kind() == reflect.Interface || rt.Kind() == reflect.Pointer {
-		rt = rt.Elem()
-	}
-	if rt.Kind() == reflect.Struct {
-		return true
-	}
-	if rt.Kind() == reflect.Slice {
-		return true
-	}
-	if rt.Kind() == reflect.Map {
-		return true
-	}
-	return false
-}
-
 func reflectMapKeyToString(key reflect.Value) string {
 	if key.Kind() == reflect.String {
 		s := key.String()

field_test.go

@@ -75,10 +75,12 @@ func TestFieldMapWithReflects(t *testing.T) {
 	m[reflect.ValueOf(1)] = reflect.ValueOf(2)
 	ks := reflectMapKeyToString(reflect.ValueOf(reflect.ValueOf(1)))
 	f := fieldAccess{owner: m, key: ks}
-	t.Log(f.value())
-	// TODO
-	val := valueAtAccessPath(m, []string{f.key})
-	t.Log(val)
+	if got, want := f.value().(reflect.Value).Int(), int64(2); got != want {
+		t.Errorf("got [%[1]v:%[1]T] want [%[2]v:%[2]T]", got, want)
+	}
+	if got, want := valueAtAccessPath(m, []string{f.key}).(reflect.Value).Int(), int64(2); got != want {
+		t.Errorf("got [%[1]v:%[1]T] want [%[2]v:%[2]T]", got, want)
+	}
 }
 
 func TestMapKeyAndBack(t *testing.T) {
@@ -227,10 +229,7 @@ func TestFieldsForMap(t *testing.T) {
 		1: 2, 3: 4,
 	}
 	l := newFields(m)
-	if got, want := len(l), 2; got != want && got != 4 { // sometimes it returns 4 TODO
-		t.Errorf("got [%v]:%T want [%v]:%T", got, got, want, want)
-	}
-	if got, want := l[0].value(), 2; got != want {
+	if got, want := len(l), 2; got != want {
 		t.Errorf("got [%v]:%T want [%v]:%T", got, got, want, want)
 	}
 }
@@ -317,3 +316,31 @@ func TestPrintStringRequest(t *testing.T) {
 		t.Errorf("got [%v]:%T want [%v]:%T", got, got, want, want)
 	}
 }
+func TestPrintStringReflectValue1(t *testing.T) {
+	rv := reflect.ValueOf(1)
+	s := printString(rv)
+	if got, want := s, "~1"; got != want {
+		t.Errorf("got [%[1]v:%[1]T] want [%[2]v:%[2]T]", got, want)
+	}
+}
+func TestPrintStringReflectValueNil(t *testing.T) {
+	rv := reflect.ValueOf(nil)
+	s := printString(rv)
+	if got, want := s, "~nil"; got != want {
+		t.Errorf("got [%[1]v:%[1]T] want [%[2]v:%[2]T]", got, want)
+	}
+}
+func TestPrintStringReflectValueReflectValueNil(t *testing.T) {
+	rv := reflect.ValueOf(reflect.ValueOf(nil))
+	s := printString(rv)
+	if got, want := s, "~nil"; got != want {
+		t.Errorf("got [%[1]v:%[1]T] want [%[2]v:%[2]T]", got, want)
+	}
+}
+func TestPrintStringReflectValueReflectValue2(t *testing.T) {
+	rv := reflect.ValueOf(reflect.ValueOf(2))
+	s := printString(rv)
+	if got, want := s, "~~2"; got != want {
+		t.Errorf("got [%[1]v:%[1]T] want [%[2]v:%[2]T]", got, want)
+	}
+}