Avoid Dart utf-8 decoder on the web

Author: simolus3

sqlite3/lib/src/implementation/database.dart

@@ -9,6 +9,7 @@ import '../constants.dart';
 import '../database.dart';
 import '../exception.dart';
 import '../functions.dart';
+import '../platform/platform.dart';
 import '../result_set.dart';
 import '../statement.dart';
 import 'bindings.dart';
@@ -393,7 +394,9 @@ base class DatabaseImplementation implements CommonDatabase {
       // or comments were parsed. That's fine, just skip over it then.
       final stmt = result.result;
       if (stmt != null) {
-        final stmtSql = utf8.decoder.convert(bytes, offset, endOffset);
+        final stmtSql = utf8Decode(
+          Uint8List.sublistView(bytes, offset, endOffset),
+        );
 
         createdStatements.add(wrapStatement(stmtSql, stmt));
       }

sqlite3/lib/src/jsonb.dart

@@ -3,6 +3,8 @@ import 'dart:typed_data';
 
 import 'package:typed_data/typed_buffers.dart';
 
+import 'platform/platform.dart';
+
 /// A [Codec] capable of converting Dart objects from and to the [JSONB] format
 /// used by sqlite3.
 ///
@@ -176,7 +178,7 @@ final class _JsonbDecodingState {
     }
 
     String payloadString() {
-      return utf8.decode(payloadBytes());
+      return utf8Decode(payloadBytes());
     }
 
     final value = switch (type) {

sqlite3/lib/src/platform/fallback.dart

@@ -1,5 +1,12 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
 import 'package:path/path.dart' as p;
 
 String pathToAbsoluteAndNormalize(String source) {
   return p.url.normalize('/$source');
 }
+
+String utf8Decode(Uint8List bytes) {
+  return utf8.decode(bytes);
+}

sqlite3/lib/src/platform/platform.dart

@@ -0,0 +1 @@
+export 'fallback.dart' if (dart.library.js_interop) 'web.dart';

sqlite3/lib/src/platform/web.dart

@@ -4,8 +4,13 @@
 /// In compiled web workers, Dart's [Uri.parse] implementation takes up a good
 /// chunk of the total file size. By using [URL] directly (which is good enough
 /// for our use case), we can avoid that implementation.
+///
+/// Additionally, we can avoid Dart's utf-8 decoder.
 library;
 
+import 'dart:js_interop';
+import 'dart:typed_data';
+
 import 'package:web/web.dart';
 
 String pathToAbsoluteAndNormalize(String source) {
@@ -15,3 +20,9 @@ String pathToAbsoluteAndNormalize(String source) {
 Iterable<String> pathComponents(String path) {
   return URL(path, 'file:///').pathname.split('/').where((e) => e.isNotEmpty);
 }
+
+String utf8Decode(Uint8List bytes) {
+  return _decoder.decode(bytes.toJS);
+}
+
+final _decoder = TextDecoder();

sqlite3/lib/src/wasm/vfs/async_opfs/sync_channel.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 import 'dart:typed_data';
 
+import '../../../platform/platform.dart';
 import '../../js_interop.dart';
 
 const protocolVersion = 1;
@@ -121,7 +122,7 @@ class MessageSerializer {
 
   String _readString(int offset) {
     final length = dataView.getInt32(offset);
-    return utf8.decode(buffer.asUint8ListSlice(offset + 4, length));
+    return utf8Decode(buffer.asUint8ListSlice(offset + 4, length));
   }
 
   void _writeString(int offset, String data) {

sqlite3/lib/src/wasm/wasm_interop.dart

@@ -6,6 +6,7 @@ import 'dart:typed_data';
 import 'package:web/web.dart';
 
 import '../implementation/bindings.dart';
+import '../platform/web.dart';
 import 'injected_values.dart';
 import 'js_interop.dart';
 
@@ -475,15 +476,15 @@ extension WrappedMemory on Memory {
 
   String readString(int address, [int? length]) {
     assert(address != 0, 'Null pointer dereference');
-    return utf8.decode(
+    return utf8Decode(
       dartBuffer.asUint8List(address, length ?? strlen(address)),
     );
   }
 
   String? readNullableString(int address, [int? length]) {
     if (address == 0) return null;
 
-    return utf8.decode(
+    return utf8Decode(
       dartBuffer.asUint8List(address, length ?? strlen(address)),
     );
   }