[WIP] configurable encoding + optimizing json access

lib/postgres.dart

@@ -1,5 +1,6 @@
 library postgres;
 
+export 'src/client_encoding.dart';
 export 'src/connection.dart';
 export 'src/execution_context.dart';
 export 'src/replication.dart' show ReplicationMode;

lib/postgres_v3_experimental.dart

@@ -190,8 +190,7 @@ abstract class PgStatement {
   Future<PgResult> run([
     Object? /* List<Object?|PgTypedParameter> | Map<String, Object?|PgTypedParameter> */
         parameters,
-  ]
-  ) async {
+  ]) async {
     final items = <PgResultRow>[];
     final subscription = bind(parameters).listen(items.add);
     await subscription.asFuture();
@@ -362,25 +361,24 @@ final class PgSessionSettings {
 
   /// The replication mode for connecting in streaming replication mode.
   ///
-  /// The default value is [ReplicationMode.none]. But when the value is set to 
-  /// [ReplicationMode.physical] or [ReplicationMode.logical], the connection 
+  /// The default value is [ReplicationMode.none]. But when the value is set to
+  /// [ReplicationMode.physical] or [ReplicationMode.logical], the connection
   /// will be established in replication mode.
   ///
   /// Please note, while in replication mode, only the Simple Query Protcol can
-  /// be used to execute queries. 
+  /// be used to execute queries.
   ///
   /// For more info, see [Streaming Replication Protocol]
   ///
   /// [Streaming Replication Protocol]: https://www.postgresql.org/docs/current/protocol-replication.html
   final ReplicationMode replicationMode;
 
-  PgSessionSettings({
-    this.connectTimeout,
-    this.timeZone,
-    this.onBadSslCertificate,
-    this.transformer,
-    this.replicationMode = ReplicationMode.none
-  });
+  PgSessionSettings(
+      {this.connectTimeout,
+      this.timeZone,
+      this.onBadSslCertificate,
+      this.transformer,
+      this.replicationMode = ReplicationMode.none});
 }
 
 final class PgPoolSettings {

lib/src/binary_codec.dart

@@ -1,9 +1,10 @@
-import 'dart:convert';
+import 'dart:convert' hide json, utf8;
 import 'dart:typed_data';
 
 import 'package:buffer/buffer.dart';
 import 'package:postgres/src/v3/types.dart';
 
+import 'client_encoding.dart';
 import 'types.dart';
 
 final _bool0 = Uint8List(1)..[0] = 0;
@@ -34,8 +35,12 @@ final _trailingZerosRegExp = RegExp(r'0+$');
 class PostgresBinaryEncoder<T extends Object>
     extends Converter<T?, Uint8List?> {
   final PgDataType<T> _dataType;
+  final ClientEncoding _clientEncoding;
 
-  const PostgresBinaryEncoder(this._dataType);
+  PostgresBinaryEncoder(
+    this._dataType, {
+    ClientEncoding? clientEncoding,
+  }) : _clientEncoding = clientEncoding ?? ClientEncoding.utf8;
 
   @override
   Uint8List? convert(Object? input) {
@@ -93,7 +98,7 @@ class PostgresBinaryEncoder<T extends Object>
       case PgDataType.varChar:
         {
           if (input is String) {
-            return castBytes(utf8.encode(input));
+            return _clientEncoding.encodeString(input);
           }
           throw FormatException(
               'Invalid type for parameter value. Expected: String Got: ${input.runtimeType}');
@@ -181,15 +186,15 @@ class PostgresBinaryEncoder<T extends Object>
 
       case PgDataType.jsonb:
         {
-          final jsonBytes = utf8.encode(json.encode(input));
+          final jsonBytes = _clientEncoding.encodeJson(input);
           final writer = ByteDataWriter(bufferLength: jsonBytes.length + 1);
           writer.writeUint8(1);
           writer.write(jsonBytes);
           return writer.toBytes();
         }
 
       case PgDataType.json:
-        return castBytes(utf8.encode(json.encode(input)));
+        return _clientEncoding.encodeJson(input);
 
       case PgDataType.byteArray:
         {
@@ -292,7 +297,7 @@ class PostgresBinaryEncoder<T extends Object>
       case PgDataType.varCharArray:
         {
           if (input is List<String>) {
-            final bytesArray = input.map((v) => utf8.encode(v));
+            final bytesArray = input.map(_clientEncoding.encodeString);
             return writeListBytes<List<int>>(bytesArray, 1043,
                 (item) => item.length, (writer, item) => writer.write(item));
           }
@@ -303,7 +308,7 @@ class PostgresBinaryEncoder<T extends Object>
       case PgDataType.textArray:
         {
           if (input is List<String>) {
-            final bytesArray = input.map((v) => utf8.encode(v));
+            final bytesArray = input.map(_clientEncoding.encodeString);
             return writeListBytes<List<int>>(bytesArray, 25,
                 (item) => item.length, (writer, item) => writer.write(item));
           }
@@ -324,7 +329,7 @@ class PostgresBinaryEncoder<T extends Object>
       case PgDataType.jsonbArray:
         {
           if (input is List<Object>) {
-            final objectsArray = input.map((v) => utf8.encode(json.encode(v)));
+            final objectsArray = input.map(_clientEncoding.encodeJson);
             return writeListBytes<List<int>>(
                 objectsArray, 3802, (item) => item.length + 1, (writer, item) {
               writer.writeUint8(1);
@@ -439,9 +444,13 @@ class PostgresBinaryEncoder<T extends Object>
 }
 
 class PostgresBinaryDecoder<T> extends Converter<Uint8List?, T?> {
-  PostgresBinaryDecoder(this.type);
-
   final PgDataType type;
+  final ClientEncoding _clientEncoding;
+
+  PostgresBinaryDecoder(
+    this.type, {
+    ClientEncoding? clientEncoding,
+  }) : _clientEncoding = clientEncoding ?? ClientEncoding.utf8;
 
   @override
   T? convert(Uint8List? input) {
@@ -456,7 +465,7 @@ class PostgresBinaryDecoder<T> extends Converter<Uint8List?, T?> {
       case PostgreSQLDataType.name:
       case PostgreSQLDataType.text:
       case PostgreSQLDataType.varChar:
-        return utf8.decode(input) as T;
+        return _clientEncoding.decodeString(input) as T;
       case PostgreSQLDataType.boolean:
         return (buffer.getInt8(0) != 0) as T;
       case PostgreSQLDataType.smallInteger:
@@ -493,11 +502,11 @@ class PostgresBinaryDecoder<T> extends Converter<Uint8List?, T?> {
           // Removes version which is first character and currently always '1'
           final bytes = input.buffer
               .asUint8List(input.offsetInBytes + 1, input.lengthInBytes - 1);
-          return json.decode(utf8.decode(bytes)) as T;
+          return _clientEncoding.decodeJson(bytes) as T;
         }
 
       case PostgreSQLDataType.json:
-        return json.decode(utf8.decode(input)) as T;
+        return _clientEncoding.decodeJson(input) as T;
 
       case PostgreSQLDataType.byteArray:
         return input as T;
@@ -545,7 +554,8 @@ class PostgresBinaryDecoder<T> extends Converter<Uint8List?, T?> {
       case PostgreSQLDataType.varCharArray:
       case PostgreSQLDataType.textArray:
         return readListBytes<String>(input, (reader, length) {
-          return utf8.decode(length > 0 ? reader.read(length) : []);
+          return _clientEncoding
+              .decodeString(length > 0 ? reader.read(length) : []);
         }) as T;
 
       case PostgreSQLDataType.doubleArray:
@@ -556,7 +566,7 @@ class PostgresBinaryDecoder<T> extends Converter<Uint8List?, T?> {
         return readListBytes<dynamic>(input, (reader, length) {
           reader.read(1);
           final bytes = reader.read(length - 1);
-          return json.decode(utf8.decode(bytes));
+          return _clientEncoding.decodeJson(bytes);
         }) as T;
 
       case PostgreSQLDataType.unknownType:
@@ -566,7 +576,7 @@ class PostgresBinaryDecoder<T> extends Converter<Uint8List?, T?> {
           // we just return the bytes and let the caller figure out what to
           // do with it.
           try {
-            return utf8.decode(input) as T;
+            return _clientEncoding.decodeString(input) as T;
           } catch (_) {
             return input as T;
           }

lib/src/client_encoding.dart

@@ -0,0 +1,23 @@
+import 'dart:convert' as c;
+import 'dart:typed_data';
+
+import 'package:buffer/buffer.dart';
+
+/// Describes the client encoding used by a connection.
+class ClientEncoding {
+  /// The Dart [Encoding] object.
+  final c.Encoding encoding;
+
+  ClientEncoding(this.encoding);
+
+  static final utf8 = ClientEncoding(c.utf8);
+
+  /// The optimized (fused encoding to/from JSON and bytes)
+  late final _jsonEncoding = c.json.fuse(encoding);
+
+  Uint8List encodeString(String input) => castBytes(encoding.encode(input));
+  Uint8List encodeJson(Object? input) => castBytes(_jsonEncoding.encode(input));
+
+  String decodeString(List<int> encoded) => encoding.decode(encoded);
+  Object? decodeJson(List<int> encoded) => _jsonEncoding.decode(encoded);
+}

lib/src/connection.dart

@@ -9,6 +9,7 @@ import 'package:buffer/buffer.dart';
 import 'package:meta/meta.dart';
 import 'auth/auth.dart';
 
+import 'client_encoding.dart';
 import 'client_messages.dart';
 import 'execution_context.dart';
 import 'message_window.dart';
@@ -19,9 +20,7 @@ import 'replication.dart';
 import 'server_messages.dart';
 
 part 'connection_fsm.dart';
-
 part 'transaction_proxy.dart';
-
 part 'exceptions.dart';
 
 /// Instances of this class connect to and communicate with a PostgreSQL database.
@@ -117,6 +116,9 @@ class PostgreSQLConnection extends Object
   /// [Streaming Replication Protocol]: https://www.postgresql.org/docs/current/protocol-replication.html
   final ReplicationMode replicationMode;
 
+  @internal
+  final clientEncoding = ClientEncoding.utf8;
+
   /// Stream of notification from the database.
   ///
   /// Listen to this [Stream] to receive events from PostgreSQL NOTIFY commands.
@@ -317,7 +319,7 @@ class PostgreSQLConnection extends Object
     // and the state node managing delivering data to the query no longer exists. Therefore,
     // as soon as a close occurs, we detach the data stream from anything that actually does
     // anything with that data.
-    _framer.addBytes(castBytes(bytes));
+    _framer.addBytes(castBytes(bytes), clientEncoding);
     while (_framer.hasMessage) {
       final msg = _framer.popMessage();
       try {