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Dart - unpack() must use eager list reader (#6723)

This commit is contained in:
Ivan Dlugos 2021-07-09 18:55:34 +02:00 committed by GitHub
parent 838c93b843
commit 3f77dc9a0e
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6 changed files with 98 additions and 47 deletions
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26
dart/lib/flat_buffers.dart
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@ -907,20 +907,34 @@ class Int8Reader extends Reader<int> {
int read(BufferContext bc, int offset) => bc._getInt8(offset);
}
/// The reader of lists of objects.
///
/// The returned unmodifiable lists lazily read objects on access.
/// The reader of lists of objects. Lazy by default - see [lazy].
class ListReader<E> extends Reader<List<E>> {
final Reader<E> _elementReader;
const ListReader(this._elementReader);
/// Enables lazy reading of the list
///
/// If true, the returned unmodifiable list lazily reads objects on access.
/// Therefore, the underlying buffer must not change while accessing the list.
///
/// If false, reads the whole list immediately on access.
final bool lazy;
const ListReader(this._elementReader, {this.lazy = true});
@override
int get size => _sizeofUint32;
@override
List<E> read(BufferContext bc, int offset) =>
new _FbGenericList<E>(_elementReader, bc, bc.derefObject(offset));
List<E> read(BufferContext bc, int offset) {
final listOffset = bc.derefObject(offset);
return lazy
? _FbGenericList<E>(_elementReader, bc, listOffset)
: List<E>.generate(
bc.buffer.getUint32(listOffset, Endian.little),
(int index) => _elementReader.read(
bc, listOffset + size + _elementReader.size * index),
growable: true);
}
}
/// Object that can read a value at a [BufferContext].

22
dart/test/flat_buffers_test.dart
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@ -763,6 +763,28 @@ class ObjectAPITest {
// final monster3 = monster2.unpack(); // MonsterT
// expect(monster3.toString(), monster.toString());
}
void test_Lists() {
// Ensure unpack() reads lists eagerly by reusing the same builder and
// overwriting data. Why: because standard reader reads lists lazily...
final fbb = Builder();
final object1 = example.TypeAliasesT(v8: [1, 2, 3], vf64: [5, 6]);
final data1 = fbb.finish(object1.pack(fbb));
final object1Read = example.TypeAliases(data1).unpack();
// overwrite the original buffer by writing to the same builder
fbb.reset();
final object2 = example.TypeAliasesT(v8: [7, 8, 9], vf64: [10, 11]);
final data2 = fbb.finish(object2.pack(fbb));
final object2Read = example.TypeAliases(data2).unpack();
// this is fine even with lazy lists:
expect(object2.toString(), object2Read.toString());
// this fails with lazy lists:
expect(object1.toString(), object1Read.toString());
}
}
class StringListWrapperImpl {

30
dart/test/monster_test_my_game.example_generated.dart
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@ -1117,15 +1117,15 @@ class Monster {
mana: mana,
hp: hp,
name: name,
inventory: inventory,
inventory: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 14),
color: color,
testType: testType,
test: test,
test4: test4?.map((e) => e.unpack()).toList(),
testarrayofstring: testarrayofstring,
testarrayofstring: const fb.ListReader<String>(const fb.StringReader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 24),
testarrayoftables: testarrayoftables?.map((e) => e.unpack()).toList(),
enemy: enemy?.unpack(),
testnestedflatbuffer: testnestedflatbuffer,
testnestedflatbuffer: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 30),
testempty: testempty?.unpack(),
testbool: testbool,
testhashs32Fnv1: testhashs32Fnv1,
@ -1136,32 +1136,32 @@ class Monster {
testhashu32Fnv1a: testhashu32Fnv1a,
testhashs64Fnv1a: testhashs64Fnv1a,
testhashu64Fnv1a: testhashu64Fnv1a,
testarrayofbools: testarrayofbools,
testarrayofbools: const fb.ListReader<bool>(const fb.BoolReader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 52),
testf: testf,
testf2: testf2,
testf3: testf3,
testarrayofstring2: testarrayofstring2,
testarrayofstring2: const fb.ListReader<String>(const fb.StringReader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 60),
testarrayofsortedstruct: testarrayofsortedstruct?.map((e) => e.unpack()).toList(),
flex: flex,
flex: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 64),
test5: test5?.map((e) => e.unpack()).toList(),
vectorOfLongs: vectorOfLongs,
vectorOfDoubles: vectorOfDoubles,
vectorOfLongs: const fb.ListReader<int>(const fb.Int64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 68),
vectorOfDoubles: const fb.ListReader<double>(const fb.Float64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 70),
parentNamespaceTest: parentNamespaceTest?.unpack(),
vectorOfReferrables: vectorOfReferrables?.map((e) => e.unpack()).toList(),
singleWeakReference: singleWeakReference,
vectorOfWeakReferences: vectorOfWeakReferences,
vectorOfWeakReferences: const fb.ListReader<int>(const fb.Uint64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 78),
vectorOfStrongReferrables: vectorOfStrongReferrables?.map((e) => e.unpack()).toList(),
coOwningReference: coOwningReference,
vectorOfCoOwningReferences: vectorOfCoOwningReferences,
vectorOfCoOwningReferences: const fb.ListReader<int>(const fb.Uint64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 84),
nonOwningReference: nonOwningReference,
vectorOfNonOwningReferences: vectorOfNonOwningReferences,
vectorOfNonOwningReferences: const fb.ListReader<int>(const fb.Uint64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 88),
anyUniqueType: anyUniqueType,
anyUnique: anyUnique,
anyAmbiguousType: anyAmbiguousType,
anyAmbiguous: anyAmbiguous,
vectorOfEnums: vectorOfEnums,
vectorOfEnums: const fb.ListReader<Color>(Color.reader, lazy: false).vTableGetNullable(_bc, _bcOffset, 98),
signedEnum: signedEnum,
testrequirednestedflatbuffer: testrequirednestedflatbuffer,
testrequirednestedflatbuffer: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 102),
scalarKeySortedTables: scalarKeySortedTables?.map((e) => e.unpack()).toList());
static int pack(fb.Builder fbBuilder, MonsterT? object) {
@ -1966,8 +1966,8 @@ class TypeAliases {
u64: u64,
f32: f32,
f64: f64,
v8: v8,
vf64: vf64);
v8: const fb.ListReader<int>(const fb.Int8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 24),
vf64: const fb.ListReader<double>(const fb.Float64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 26));
static int pack(fb.Builder fbBuilder, TypeAliasesT? object) {
if (object == null) return 0;

33
src/idl_gen_dart.cpp
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@ -330,7 +330,8 @@ class DartGenerator : public BaseGenerator {
std::string GenReaderTypeName(const Type &type, Namespace *current_namespace,
const FieldDef &def,
bool parent_is_vector = false) {
bool parent_is_vector = false,
bool lazy = true) {
if (type.base_type == BASE_TYPE_BOOL) {
return "const " + _kFb + ".BoolReader()";
} else if (IsVector(type)) {
@ -338,7 +339,7 @@ class DartGenerator : public BaseGenerator {
GenDartTypeName(type.VectorType(), current_namespace, def) + ">(" +
GenReaderTypeName(type.VectorType(), current_namespace, def,
true) +
")";
(lazy ? ")" : ", lazy: false)");
} else if (IsString(type)) {
return "const " + _kFb + ".StringReader()";
}
@ -556,18 +557,32 @@ class DartGenerator : public BaseGenerator {
std::string field_name = MakeCamel(field.name, false);
if (!constructor_args.empty()) constructor_args += ",\n";
constructor_args += " " + field_name + ": " + field_name;
constructor_args += " " + field_name + ": ";
const Type &type = field.value.type;
bool isNullable =
getDefaultValue(field.value).empty() && !struct_def.fixed;
std::string defaultValue = getDefaultValue(field.value);
bool isNullable = defaultValue.empty() && !struct_def.fixed;
std::string nullableValueAccessOperator = isNullable ? "?" : "";
if (type.base_type == BASE_TYPE_STRUCT) {
constructor_args += nullableValueAccessOperator + ".unpack()";
} else if (type.base_type == BASE_TYPE_VECTOR &&
type.VectorType().base_type == BASE_TYPE_STRUCT) {
constructor_args +=
nullableValueAccessOperator + ".map((e) => e.unpack()).toList()";
field_name + nullableValueAccessOperator + ".unpack()";
} else if (type.base_type == BASE_TYPE_VECTOR) {
if (type.VectorType().base_type == BASE_TYPE_STRUCT) {
constructor_args += field_name + nullableValueAccessOperator +
".map((e) => e.unpack()).toList()";
} else {
constructor_args +=
GenReaderTypeName(field.value.type, struct_def.defined_namespace,
field, false, false);
constructor_args += ".vTableGet";
std::string offset = NumToString(field.value.offset);
constructor_args +=
isNullable
? "Nullable(_bc, _bcOffset, " + offset + ")"
: "(_bc, _bcOffset, " + offset + ", " + defaultValue + ")";
}
} else {
constructor_args += field_name;
}
}

4
tests/monster_extra_my_game_generated.dart
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@ -44,8 +44,8 @@ class MonsterExtra {
f1: f1,
f2: f2,
f3: f3,
dvec: dvec,
fvec: fvec);
dvec: const fb.ListReader<double>(const fb.Float64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 20),
fvec: const fb.ListReader<double>(const fb.Float32Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 22));
static int pack(fb.Builder fbBuilder, MonsterExtraT? object) {
if (object == null) return 0;

30
tests/monster_test_my_game.example_generated.dart
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@ -1117,15 +1117,15 @@ class Monster {
mana: mana,
hp: hp,
name: name,
inventory: inventory,
inventory: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 14),
color: color,
testType: testType,
test: test,
test4: test4?.map((e) => e.unpack()).toList(),
testarrayofstring: testarrayofstring,
testarrayofstring: const fb.ListReader<String>(const fb.StringReader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 24),
testarrayoftables: testarrayoftables?.map((e) => e.unpack()).toList(),
enemy: enemy?.unpack(),
testnestedflatbuffer: testnestedflatbuffer,
testnestedflatbuffer: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 30),
testempty: testempty?.unpack(),
testbool: testbool,
testhashs32Fnv1: testhashs32Fnv1,
@ -1136,32 +1136,32 @@ class Monster {
testhashu32Fnv1a: testhashu32Fnv1a,
testhashs64Fnv1a: testhashs64Fnv1a,
testhashu64Fnv1a: testhashu64Fnv1a,
testarrayofbools: testarrayofbools,
testarrayofbools: const fb.ListReader<bool>(const fb.BoolReader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 52),
testf: testf,
testf2: testf2,
testf3: testf3,
testarrayofstring2: testarrayofstring2,
testarrayofstring2: const fb.ListReader<String>(const fb.StringReader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 60),
testarrayofsortedstruct: testarrayofsortedstruct?.map((e) => e.unpack()).toList(),
flex: flex,
flex: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 64),
test5: test5?.map((e) => e.unpack()).toList(),
vectorOfLongs: vectorOfLongs,
vectorOfDoubles: vectorOfDoubles,
vectorOfLongs: const fb.ListReader<int>(const fb.Int64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 68),
vectorOfDoubles: const fb.ListReader<double>(const fb.Float64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 70),
parentNamespaceTest: parentNamespaceTest?.unpack(),
vectorOfReferrables: vectorOfReferrables?.map((e) => e.unpack()).toList(),
singleWeakReference: singleWeakReference,
vectorOfWeakReferences: vectorOfWeakReferences,
vectorOfWeakReferences: const fb.ListReader<int>(const fb.Uint64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 78),
vectorOfStrongReferrables: vectorOfStrongReferrables?.map((e) => e.unpack()).toList(),
coOwningReference: coOwningReference,
vectorOfCoOwningReferences: vectorOfCoOwningReferences,
vectorOfCoOwningReferences: const fb.ListReader<int>(const fb.Uint64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 84),
nonOwningReference: nonOwningReference,
vectorOfNonOwningReferences: vectorOfNonOwningReferences,
vectorOfNonOwningReferences: const fb.ListReader<int>(const fb.Uint64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 88),
anyUniqueType: anyUniqueType,
anyUnique: anyUnique,
anyAmbiguousType: anyAmbiguousType,
anyAmbiguous: anyAmbiguous,
vectorOfEnums: vectorOfEnums,
vectorOfEnums: const fb.ListReader<Color>(Color.reader, lazy: false).vTableGetNullable(_bc, _bcOffset, 98),
signedEnum: signedEnum,
testrequirednestedflatbuffer: testrequirednestedflatbuffer,
testrequirednestedflatbuffer: const fb.ListReader<int>(const fb.Uint8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 102),
scalarKeySortedTables: scalarKeySortedTables?.map((e) => e.unpack()).toList());
static int pack(fb.Builder fbBuilder, MonsterT? object) {
@ -1966,8 +1966,8 @@ class TypeAliases {
u64: u64,
f32: f32,
f64: f64,
v8: v8,
vf64: vf64);
v8: const fb.ListReader<int>(const fb.Int8Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 24),
vf64: const fb.ListReader<double>(const fb.Float64Reader(), lazy: false).vTableGetNullable(_bc, _bcOffset, 26));
static int pack(fb.Builder fbBuilder, TypeAliasesT? object) {
if (object == null) return 0;