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[Proto] Support polymorphic serialization for derived classes #63

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01740cf
[Proto] Add reflection support for polymorphic serialization for deri…
kengwang Sep 16, 2025
a2ded7b
[Proto] Allow fallback to base type
kengwang Sep 16, 2025
3d45b86
[Proto] Use generic attribute to avoid boxing
kengwang Sep 17, 2025
c4c5d0c
[Proto] Polymorphic derived type reuse converter logic
kengwang Sep 17, 2025
1adeaa6
[Proto] Add .Generator support
kengwang Sep 18, 2025
14b739c
[Proto] Add derived type (de)serialization support
kengwang Oct 5, 2025
d72fa4f
[Proto] Fix warnings
kengwang Oct 5, 2025
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28 changes: 28 additions & 0 deletions Lagrange.Proto.Generator/Entity/PolymorphicTypeInfo.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,28 @@
using Microsoft.CodeAnalysis;

namespace Lagrange.Proto.Generator.Entity;

public class PolymorphicTypeInfo
{
public INamedTypeSymbol PolymorphicKeyType { get; internal set; } = null!;

public uint PolymorphicIndicateIndex { get; internal set; } = 0;

public bool PolymorphicFallbackToBaseType { get; internal set; } = true;

public List<PolymorphicDerivedTypeInfo> PolymorphicTypes { get; } = [];
}

public class PolymorphicDerivedTypeInfo
{
public INamedTypeSymbol DerivedType { get; internal set; } = null!;
public TypedConstant Key { get; internal set; }
}

public class BaseTypeInfo
{
public INamedTypeSymbol BaseType { get; internal set; } = null!;
public PolymorphicTypeInfo PolymorphicInfo { get; internal set; } = new();
public bool IgnoreDefaultFields { get; internal set; }
public Dictionary<int, ProtoFieldInfo> Fields { get; } = new();
}
45 changes: 44 additions & 1 deletion Lagrange.Proto.Generator/ProtoSourceGenerator.Emitter.Serialize.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,22 +25,65 @@ private partial class Emitter
private const string EncodeStringMethodName = "EncodeString";
private const string EncodeBytesMethodName = "EncodeBytes";
private const string EncodeResolvableMethodName = "EncodeResolvable";


private void EmitSerializeMethod(SourceWriter source)
{
source.WriteLine($"public static void SerializeHandler({_fullQualifiedName} {ObjectVarName}, {ProtoWriterTypeRef} {WriterVarName})");
source.WriteLine("{");
source.Indentation++;


if (parser.BaseTypeInfo?.BaseType.GetFullName() != _fullQualifiedName && parser.BaseTypeInfo?.PolymorphicInfo.PolymorphicIndicateIndex is > 0)
{
source.WriteLine($"{parser.BaseTypeInfo.BaseType.GetFullName()}.SerializeHandler({ObjectVarName},{WriterVarName});");
}
else
{
source.WriteLine($"SerializeHandlerCore({ObjectVarName}, {WriterVarName});");
}

source.Indentation--;
source.WriteLine("}");
source.WriteLine();

source.WriteLine($"public static void SerializeHandlerCore({_fullQualifiedName} {ObjectVarName}, {ProtoWriterTypeRef} {WriterVarName})");
source.WriteLine("{");
source.Indentation++;
if (parser.PolymorphicInfo.PolymorphicIndicateIndex > 0)
{
// write indicate field first
var idx = (int)parser.PolymorphicInfo.PolymorphicIndicateIndex;
var indicatorField = parser.Fields[idx];
EmitMembers(source, idx, indicatorField);
source.WriteLine();

source.WriteLine($"switch ({ObjectVarName})");
source.WriteLine("{");
source.Indentation++;
for (var index = 0; index < parser.PolymorphicInfo.PolymorphicTypes.Count; index++)
{
var kv = parser.PolymorphicInfo.PolymorphicTypes[index];
source.WriteLine($"case {kv.DerivedType.GetFullName()} _:");
source.Indentation++;
source.WriteLine($"{kv.DerivedType.GetFullName()}.SerializeHandlerCore(({kv.DerivedType.GetFullName()}){ObjectVarName}, {WriterVarName});");
source.WriteLine("break;");
source.Indentation--;
}
source.Indentation--;
source.WriteLine("}");
source.WriteLine();
}
foreach (var kv in parser.Fields)
{
int field = kv.Key;
if (parser.PolymorphicInfo.PolymorphicIndicateIndex == field) continue; // already written
var info = kv.Value;

EmitMembers(source, field, info);
source.WriteLine();
}


source.Indentation--;
source.WriteLine("}");
}
Expand Down
133 changes: 120 additions & 13 deletions Lagrange.Proto.Generator/ProtoSourceGenerator.Emitter.TypeInfo.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
using Lagrange.Proto.Generator.Utility;
using Lagrange.Proto.Generator.Utility.Extension;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;

namespace Lagrange.Proto.Generator;

Expand All @@ -13,6 +14,9 @@ private partial class Emitter
private const string TypeInfoPropertyName = "TypeInfo";

private const string ProtoObjectInfoTypeRef = "global::Lagrange.Proto.Serialization.Metadata.ProtoObjectInfo<{0}>";
private const string ProtoPolymorphicObjectInfoTypeRef = "global::Lagrange.Proto.Serialization.Metadata.ProtoPolymorphicObjectInfo<{0}>";
private const string ProtoPolymorphicDerivedTypeDescriptorTypeRef = "global::Lagrange.Proto.Serialization.Metadata.ProtoPolymorphicDerivedTypeDescriptor<{0}>";
private const string ProtoPolymorphicDerivedTypeDescriptorBaseTypeRef = "global::Lagrange.Proto.Serialization.Metadata.ProtoPolymorphicDerivedTypeDescriptor";
private const string ProtoFieldInfoTypeRef = "global::Lagrange.Proto.Serialization.Metadata.ProtoFieldInfo";
private const string ProtoFieldInfoGenericTypeRef = "global::Lagrange.Proto.Serialization.Metadata.ProtoFieldInfo<{0}>";
private const string ProtoMapFieldInfoGenericTypeRef = "global::Lagrange.Proto.Serialization.Metadata.ProtoMapFieldInfo<{0}, {1}, {2}>";
Expand All @@ -37,11 +41,15 @@ private partial class Emitter

private void EmitTypeInfo(SourceWriter source)
{
source.WriteLine("#pragma warning disable CS0108");
source.WriteLine();
source.WriteLine($"public static {ProtoObjectInfoTypeRefGeneric}? {TypeInfoFieldName};");
source.WriteLine();

source.WriteLine($"public static {ProtoObjectInfoTypeRefGeneric} {TypeInfoPropertyName} => {TypeInfoFieldName} ??= GetTypeInfo();");
source.WriteLine();
source.WriteLine("#pragma warning restore CS0108");
source.WriteLine();

source.WriteLine($"private static {ProtoObjectInfoTypeRefGeneric} GetTypeInfo()");
source.WriteLine('{');
Expand All @@ -60,28 +68,20 @@ private void EmitTypeInfo(SourceWriter source)
source.WriteLine($"return new {ProtoObjectInfoTypeRefGeneric}()");
source.WriteLine('{');
source.Indentation++;

source.WriteLine($"Fields = new global::System.Collections.Generic.Dictionary<uint, {string.Format(ProtoFieldInfoTypeRef)}>()");
source.WriteLine('{');
source.Indentation++;
foreach (var kv in parser.Fields)
{
int field = kv.Key;
var info = kv.Value;

if (info.ExtraTypeInfo.Count == 0) EmitFieldInfo(source, field, info);
else EmitMapFieldInfo(source, field, info);
}
source.Indentation--;
source.WriteLine("},");
EmitFieldsInfo(source, parser.Fields);

source.WriteLine($"ObjectCreator = () => new {_fullQualifiedName}(),");
EmitPolymorphicInfo(source, parser.PolymorphicInfo, parser.BaseTypeInfo!);
source.WriteLine($"IgnoreDefaultFields = {parser.IgnoreDefaultFields.ToString().ToLower()}");

source.Indentation--;
source.WriteLine("};");
source.Indentation--;
source.WriteLine('}');

EmitPolymorphicDerivedTypeDescriptor(source, parser.PolymorphicInfo);

return;

static void EmitByTypeSymbol(SourceWriter source, ITypeSymbol typeSymbol)
Expand All @@ -106,6 +106,23 @@ static void EmitByTypeSymbol(SourceWriter source, ITypeSymbol typeSymbol)
}
}

private void EmitFieldsInfo(SourceWriter source,Dictionary<int, ProtoFieldInfo> fields )
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Copilot AI Oct 5, 2025

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[nitpick] Missing space after comma in parameter list. Should be SourceWriter source, Dictionary<int, ProtoFieldInfo> fields.

Suggested change
private void EmitFieldsInfo(SourceWriter source,Dictionary<int, ProtoFieldInfo> fields )
private void EmitFieldsInfo(SourceWriter source, Dictionary<int, ProtoFieldInfo> fields )

Copilot uses AI. Check for mistakes.

{
source.WriteLine($"Fields = new global::System.Collections.Generic.Dictionary<uint, {string.Format(ProtoFieldInfoTypeRef)}>()");
source.WriteLine('{');
source.Indentation++;
foreach (var kv in fields)
{
int field = kv.Key;
var info = kv.Value;

if (info.ExtraTypeInfo.Count == 0) EmitFieldInfo(source, field, info);
else EmitMapFieldInfo(source, field, info);
}
source.Indentation--;
source.WriteLine("},");
}

private void EmitFieldInfo(SourceWriter source, int field, ProtoFieldInfo info)
{
int tag = field << 3 | (byte)info.WireType;
Expand Down Expand Up @@ -142,5 +159,95 @@ private void EmitMapFieldInfo(SourceWriter source, int field, ProtoFieldInfo inf
source.Indentation--;
source.WriteLine("},");
}

private void EmitPolymorphicInfo(SourceWriter source, PolymorphicTypeInfo polymorphicInfo, BaseTypeInfo baseTypeInfo)
{
if (polymorphicInfo.PolymorphicIndicateIndex == 0) return;
source.WriteLine($"PolymorphicInfo = new {string.Format(ProtoPolymorphicObjectInfoTypeRef, polymorphicInfo.PolymorphicKeyType.GetFullName())}()");
source.WriteLine('{');
source.Indentation++;

source.WriteLine($"PolymorphicIndicateIndex = {polymorphicInfo.PolymorphicIndicateIndex},");
source.WriteLine($"PolymorphicFallbackToBaseType = {polymorphicInfo.PolymorphicFallbackToBaseType.ToString().ToLower()},");
if (parser.BaseTypeInfo?.BaseType is not null && parser.BaseTypeInfo.BaseType.GetFullName() != _fullQualifiedName)
{
source.WriteLine($"RootTypeDescriptorGetter = () => new {string.Format(ProtoPolymorphicDerivedTypeDescriptorTypeRef, parser.BaseTypeInfo.BaseType.GetFullName())}()");
source.WriteLine('{');
source.Indentation++;
source.WriteLine($"FieldsGetter = () => {parser.BaseTypeInfo.BaseType.GetFullName()}.{TypeInfoPropertyName}.Fields,");
source.WriteLine($"ObjectCreator = () => new {parser.BaseTypeInfo.BaseType.GetFullName()}(),");
source.WriteLine($"IgnoreDefaultFieldsGetter = () => {parser.BaseTypeInfo.BaseType.GetFullName()}.{TypeInfoPropertyName}.IgnoreDefaultFields,");
source.WriteLine($"PolymorphicInfoGetter = () => {parser.BaseTypeInfo.BaseType.GetFullName()}.{TypeInfoPropertyName}.PolymorphicInfo,");
source.WriteLine($"CurrentType = typeof({parser.BaseTypeInfo.BaseType.GetFullName()})");
source.Indentation--;
source.WriteLine("},");
}
source.WriteLine(
$"PolymorphicDerivedTypes = new global::System.Collections.Generic.Dictionary<{polymorphicInfo.PolymorphicKeyType.GetFullName()}, {ProtoPolymorphicDerivedTypeDescriptorBaseTypeRef}>()");
source.WriteLine('{');
source.Indentation++;

foreach (var derivedTypeInfo in polymorphicInfo.PolymorphicTypes)
{
source.WriteLine($"[{derivedTypeInfo.Key.ToCSharpString()}] = new {string.Format(ProtoPolymorphicDerivedTypeDescriptorTypeRef, baseTypeInfo.BaseType.GetFullName())}()");
source.WriteLine('{');
source.Indentation++;
source.WriteLine($"CurrentType = typeof({derivedTypeInfo.DerivedType.GetFullName()}),");
source.WriteLine($"FieldsGetter = () => {derivedTypeInfo.DerivedType.GetFullName()}.{TypeInfoPropertyName}.Fields,");
source.WriteLine($"ObjectCreator = () => ({baseTypeInfo.BaseType.GetFullName()})new {derivedTypeInfo.DerivedType.GetFullName()}(),");
source.WriteLine($"IgnoreDefaultFieldsGetter = () => {derivedTypeInfo.DerivedType.GetFullName()}.{TypeInfoPropertyName}.IgnoreDefaultFields,");
source.WriteLine($"PolymorphicInfoGetter = () => {derivedTypeInfo.DerivedType.GetFullName()}.{TypeInfoPropertyName}.PolymorphicInfo");
source.Indentation--;
source.WriteLine("},");
}

source.Indentation--;
source.WriteLine("}");
source.Indentation--;
source.WriteLine("},");
}

private void EmitPolymorphicDerivedTypeDescriptor(SourceWriter source, PolymorphicTypeInfo polymorphicInfo)
{

source.WriteLine("#pragma warning disable CS0108");
source.WriteLine(
$"public static {string.Format(ProtoPolymorphicDerivedTypeDescriptorTypeRef,_fullQualifiedName)}? GetPolymorphicTypeDescriptor<TKey>(TKey discriminator)");
source.WriteLine('{');
source.Indentation++;
if (polymorphicInfo.PolymorphicIndicateIndex > 0)
{
source.WriteLine("switch (discriminator)");
source.WriteLine('{');
source.Indentation++;

foreach (var derivedTypeInfo in polymorphicInfo.PolymorphicTypes)
{
source.WriteLine($"case {derivedTypeInfo.Key.ToCSharpString()}: return new {string.Format(ProtoPolymorphicDerivedTypeDescriptorTypeRef, _fullQualifiedName)}()");
source.WriteLine('{');
source.Indentation++;
source.WriteLine($"FieldsGetter = () => {derivedTypeInfo.DerivedType.GetFullName()}.{TypeInfoPropertyName}.Fields,");
source.WriteLine($"ObjectCreator = () => ({_fullQualifiedName})new {derivedTypeInfo.DerivedType.GetFullName()}(),");
source.WriteLine($"IgnoreDefaultFieldsGetter = () => {derivedTypeInfo.DerivedType.GetFullName()}.{TypeInfoPropertyName}.IgnoreDefaultFields,");
source.WriteLine($"PolymorphicInfoGetter = () => {derivedTypeInfo.DerivedType.GetFullName()}.{TypeInfoPropertyName}.PolymorphicInfo,");
source.WriteLine($"CurrentType = typeof({derivedTypeInfo.DerivedType.GetFullName()})");
source.Indentation--;
source.WriteLine("};");
}

source.WriteLine("default: return null;");
source.Indentation--;
source.WriteLine("}");
}
else
{
source.WriteLine("return null;");
}

source.Indentation--;
source.WriteLine('}');
source.WriteLine("#pragma warning restore CS0108");
source.WriteLine();
}
}
}
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