Dart - make vTable deduplication optional (#6734)

5 files changed, 36 insertions, 29 deletions

diff --git a/dart/example/monster_my_game.sample_generated.dart b/dart/example/monster_my_game.sample_generated.dart
index f5ab93ca..eae52b61 100644
--- a/dart/example/monster_my_game.sample_generated.dart
+++ b/dart/example/monster_my_game.sample_generated.dart
@@ -166,7 +166,7 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -334,7 +334,7 @@ class MonsterObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -416,7 +416,7 @@ class WeaponObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
diff --git a/dart/lib/flat_buffers.dart b/dart/lib/flat_buffers.dart
index 1ab410d3..ca635feb 100644
--- a/dart/lib/flat_buffers.dart
+++ b/dart/lib/flat_buffers.dart
@@ -108,8 +108,9 @@ class Builder {
   final int initialSize;
 
   /// The list of existing VTable(s).
-  final List<int> _vTables = List<int>.filled(16, 0, growable: true)
-    ..length = 0;
+  final List<int> _vTables;
+
+  final bool deduplicateTables;
 
   ByteData _buf;
 
@@ -146,8 +147,10 @@ class Builder {
     this.initialSize: 1024,
     bool internStrings = false,
     Allocator allocator = const DefaultAllocator(),
+    this.deduplicateTables = true,
   })  : _allocator = allocator,
-        _buf = allocator.allocate(initialSize) {
+        _buf = allocator.allocate(initialSize),
+        _vTables = deduplicateTables ? [] : const [] {
     if (internStrings) {
       _strings = new Map<String, int>();
     }
@@ -309,26 +312,30 @@ class Builder {
     int? vTableTail;
     {
       currentVTable.computeFieldOffsets(tableTail);
+
       // Try to find an existing compatible VTable.
-      // Search backward - more likely to have recently used one
-      for (int i = _vTables.length - 1; i >= 0; i--) {
-        final int vt2Offset = _vTables[i];
-        final int vt2Start = _buf.lengthInBytes - vt2Offset;
-        final int vt2Size = _buf.getUint16(vt2Start, Endian.little);
-
-        if (currentVTable._vTableSize == vt2Size &&
-            currentVTable._offsetsMatch(vt2Start, _buf)) {
-          vTableTail = vt2Offset;
-          break;
+      if (deduplicateTables) {
+        // Search backward - more likely to have recently used one
+        for (int i = _vTables.length - 1; i >= 0; i--) {
+          final int vt2Offset = _vTables[i];
+          final int vt2Start = _buf.lengthInBytes - vt2Offset;
+          final int vt2Size = _buf.getUint16(vt2Start, Endian.little);
+
+          if (currentVTable._vTableSize == vt2Size &&
+              currentVTable._offsetsMatch(vt2Start, _buf)) {
+            vTableTail = vt2Offset;
+            break;
+          }
         }
       }
+
       // Write a new VTable.
       if (vTableTail == null) {
         _prepare(_sizeofUint16, _currentVTable!.numOfUint16);
         vTableTail = _tail;
         currentVTable.tail = vTableTail;
         currentVTable.output(_buf, _buf.lengthInBytes - _tail);
-        _vTables.add(currentVTable.tail);
+        if (deduplicateTables) _vTables.add(currentVTable.tail);
       }
     }
     // Set the VTable offset.
@@ -459,7 +466,7 @@ class Builder {
     _maxAlign = 1;
     _tail = 0;
     _currentVTable = null;
-    _vTables.length = 0;
+    if (deduplicateTables) _vTables.clear();
     if (_strings != null) {
       _strings = new Map<String, int>();
     }
diff --git a/dart/test/monster_test_my_game.example2_generated.dart b/dart/test/monster_test_my_game.example2_generated.dart
index 60ac656a..82c3f4ba 100644
--- a/dart/test/monster_test_my_game.example2_generated.dart
+++ b/dart/test/monster_test_my_game.example2_generated.dart
@@ -69,7 +69,7 @@ class MonsterObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
diff --git a/dart/test/monster_test_my_game.example_generated.dart b/dart/test/monster_test_my_game.example_generated.dart
index c21d8516..5d11bb71 100644
--- a/dart/test/monster_test_my_game.example_generated.dart
+++ b/dart/test/monster_test_my_game.example_generated.dart
@@ -346,7 +346,7 @@ class TestObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -444,7 +444,7 @@ class TestSimpleTableWithEnumObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -591,7 +591,7 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -689,7 +689,7 @@ class AbilityObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -797,7 +797,7 @@ class StructOfStructsObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -923,7 +923,7 @@ class StatObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -1021,7 +1021,7 @@ class ReferrableObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -1890,7 +1890,7 @@ class MonsterObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
@@ -2139,7 +2139,7 @@ class TypeAliasesObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;
diff --git a/dart/test/monster_test_my_game_generated.dart b/dart/test/monster_test_my_game_generated.dart
index eef9e73d..7f0fcda5 100644
--- a/dart/test/monster_test_my_game_generated.dart
+++ b/dart/test/monster_test_my_game_generated.dart
@@ -69,7 +69,7 @@ class InParentNamespaceObjectBuilder extends fb.ObjectBuilder {
   /// Convenience method to serialize to byte list.
   @override
   Uint8List toBytes([String? fileIdentifier]) {
-    fb.Builder fbBuilder = new fb.Builder();
+    fb.Builder fbBuilder = new fb.Builder(deduplicateTables: false);
     int offset = finish(fbBuilder);
     fbBuilder.finish(offset, fileIdentifier);
     return fbBuilder.buffer;