Replace Nest in KeyValue interface with LogMarshalerFunc type

This reduces the KeyValue interface while still allowing a function
to be used to build an object using LogMarshalerFunc

json_encoder.go

@@ -117,22 +117,15 @@ func (enc *jsonEncoder) AddFloat64(key string, val float64) {
 	}
 }
 
-// Nest allows the caller to populate a nested object under the provided key.
-func (enc *jsonEncoder) Nest(key string, f func(KeyValue) error) error {
-	enc.addKey(key)
-	enc.bytes = append(enc.bytes, '{')
-	err := f(enc)
-	enc.bytes = append(enc.bytes, '}')
-	return err
-}
-
 // AddMarshaler adds a LogMarshaler to the encoder's fields.
 //
 // TODO: Encode the error into the message instead of returning.
 func (enc *jsonEncoder) AddMarshaler(key string, obj LogMarshaler) error {
-	return enc.Nest(key, func(kv KeyValue) error {
-		return obj.MarshalLog(kv)
-	})
+	enc.addKey(key)
+	enc.bytes = append(enc.bytes, '{')
+	err := obj.MarshalLog(enc)
+	enc.bytes = append(enc.bytes, '}')
+	return err
 }
 
 // AddObject uses reflection to add an arbitrary object to the logging context.

json_encoder_bench_test.go

@@ -41,7 +41,7 @@ func BenchmarkJSONEncoderNest(b *testing.B) {
 	}
 	for i := 0; i < b.N; i++ {
 		enc := newJSONEncoder()
-		enc.Nest("nested", f)
+		enc.AddMarshaler("nested", LogMarshalerFunc(f))
 		enc.Free()
 	}
 }

json_encoder_test.go

@@ -149,18 +149,18 @@ func TestJSONWriteMessage(t *testing.T) {
 	})
 }
 
-func TestJSONNest(t *testing.T) {
-	withJSONEncoder(func(enc *jsonEncoder) {
-		err := enc.Nest("nested", func(kv KeyValue) error {
-			kv.AddString("sub-foo", "sub-bar")
-			return nil
-		})
-		require.NoError(t, err, "Unexpected error using Nest.")
-		enc.AddString("baz", "bing")
-
-		assertJSON(t, `"foo":"bar","nested":{"sub-foo":"sub-bar"},"baz":"bing"`, enc)
-	})
-}
+// func TestJSONNest(t *testing.T) {
+// 	withJSONEncoder(func(enc *jsonEncoder) {
+// 		err := enc.Nest("nested", func(kv KeyValue) error {
+// 			kv.AddString("sub-foo", "sub-bar")
+// 			return nil
+// 		})
+// 		require.NoError(t, err, "Unexpected error using Nest.")
+// 		enc.AddString("baz", "bing")
+
+// 		assertJSON(t, `"foo":"bar","nested":{"sub-foo":"sub-bar"},"baz":"bing"`, enc)
+// 	})
+// }
 
 type loggable struct{}
 

keyvalue.go

@@ -35,5 +35,4 @@ type KeyValue interface {
 	// allocation-heavy. Consider implementing the LogMarshaler interface instead.
 	AddObject(string, interface{})
 	AddString(string, string)
-	Nest(string, func(KeyValue) error) error
 }

marshaler.go

@@ -26,3 +26,12 @@ package zap
 type LogMarshaler interface {
 	MarshalLog(KeyValue) error
 }
+
+// LogMarshalerFunc is a type adapter that allows using a function as a
+// LogMarshaler.
+type LogMarshalerFunc func(KeyValue) error
+
+// MarshalLog calls the underlying function.
+func (f LogMarshalerFunc) MarshalLog(kv KeyValue) error {
+	return f(kv)
+}