public static Func <Unpacker, DasherContext, object> Build(Type type, UnexpectedFieldBehaviour unexpectedFieldBehaviour, DasherContext context)
{
// Create a collection for errors, initially with zero capacity (minimal allocation)
var errors = new List <string>(0);
// Validate that the type is suitable as a top-level type
context.ValidateTopLevelType(type, errors);
// Throw if there were any errors
if (errors.Any())
{
throw new DeserialiserGenerationException(errors, type);
}
// Initialise code gen
var method = new DynamicMethod(
$"Generated{type.Name}Deserialiser",
returnType: typeof(object),
parameterTypes: new[] { typeof(Unpacker), typeof(DasherContext) },
restrictedSkipVisibility: true);
var ilg = method.GetILGenerator();
// Convert args to locals, so we can pass them around
var unpacker = ilg.DeclareLocal(typeof(Unpacker));
ilg.Emit(OpCodes.Ldarg_0);
ilg.Emit(OpCodes.Stloc, unpacker);
var contextLocal = ilg.DeclareLocal(typeof(DasherContext));
ilg.Emit(OpCodes.Ldarg_1);
ilg.Emit(OpCodes.Stloc, contextLocal);
var valueLocal = ilg.DeclareLocal(type);
var throwBlocks = new ThrowBlockGatherer(ilg);
if (!TryEmitDeserialiseCode(ilg, throwBlocks, errors, "<root>", type, valueLocal, unpacker, context, contextLocal, unexpectedFieldBehaviour, isRoot: true))
{
Debug.Assert(errors.Any());
throw new DeserialiserGenerationException(errors, type);
}
ilg.Emit(OpCodes.Ldloc, valueLocal);
if (type.GetTypeInfo().IsValueType)
{
ilg.Emit(OpCodes.Box, type);
}
// Return the newly constructed object!
ilg.Emit(OpCodes.Ret);
// Write all the exception handling blocks out of line
throwBlocks.Flush();
// Return a delegate that performs the above operations
return((Func <Unpacker, DasherContext, object>)method.CreateDelegate(typeof(Func <Unpacker, DasherContext, object>)));
}
public static bool TryEmitDeserialiseCode(ILGenerator ilg, ThrowBlockGatherer throwBlocks, ICollection <string> errors, string name, Type targetType, LocalBuilder value, LocalBuilder unpacker, DasherContext context, LocalBuilder contextLocal, UnexpectedFieldBehaviour unexpectedFieldBehaviour, bool isRoot = false)
{
if (!context.TryGetTypeProvider(value.LocalType, errors, out ITypeProvider provider))
{
return(false);
}
if (!isRoot && provider is ComplexTypeProvider)
{
ilg.Emit(OpCodes.Ldloc, contextLocal);
ilg.LoadType(value.LocalType);
ilg.Emit(OpCodes.Ldc_I4, (int)unexpectedFieldBehaviour);
ilg.Emit(OpCodes.Call, Methods.DasherContext_GetOrCreateDeserialiseFunc);
ilg.Emit(OpCodes.Ldloc, unpacker);
ilg.Emit(OpCodes.Ldloc, contextLocal);
ilg.Emit(OpCodes.Call, Methods.DasherDeserialiseFunc_Invoke);
ilg.Emit(value.LocalType.GetTypeInfo().IsValueType ? OpCodes.Unbox_Any : OpCodes.Castclass, value.LocalType);
ilg.Emit(OpCodes.Stloc, value);
}
else
{
var end = ilg.DefineLabel();
if (provider.UseDefaultNullHandling(value.LocalType))
{
// check for null
var nonNullLabel = ilg.DefineLabel();
ilg.Emit(OpCodes.Ldloc, unpacker);
ilg.Emit(OpCodes.Call, Methods.Unpacker_TryReadNull);
ilg.Emit(OpCodes.Brfalse_S, nonNullLabel);
{
ilg.Emit(OpCodes.Ldnull);
ilg.Emit(OpCodes.Stloc, value);
ilg.Emit(OpCodes.Br, end);
}
ilg.MarkLabel(nonNullLabel);
}
if (!provider.TryEmitDeserialiseCode(ilg, throwBlocks, errors, name, targetType, value, unpacker, contextLocal, context, unexpectedFieldBehaviour))
{
return(false);
}
ilg.MarkLabel(end);
}
return(true);
}
public static bool TryEmitSerialiseCode(ILGenerator ilg, ThrowBlockGatherer throwBlocks, ICollection <string> errors, LocalBuilder value, LocalBuilder packer, DasherContext context, LocalBuilder contextLocal, bool isRoot = false)
{
if (!context.TryGetTypeProvider(value.LocalType, errors, out ITypeProvider provider))
{
return(false);
}
if (!isRoot && provider is ComplexTypeProvider)
{
// prevent endless code generation for recursive types by delegating to a method call
ilg.Emit(OpCodes.Ldloc, contextLocal);
ilg.LoadType(value.LocalType);
ilg.Emit(OpCodes.Call, Methods.DasherContext_GetOrCreateSerialiseAction);
ilg.Emit(OpCodes.Ldloc, packer);
ilg.Emit(OpCodes.Ldloc, contextLocal);
ilg.Emit(OpCodes.Ldloc, value);
if (value.LocalType.GetTypeInfo().IsValueType)
{
ilg.Emit(OpCodes.Box, value.LocalType);
}
ilg.Emit(OpCodes.Call, Methods.DasherSerialiseAction_Invoke);
}
else
{
var end = ilg.DefineLabel();
if (provider.UseDefaultNullHandling(value.LocalType))
{
var nonNull = ilg.DefineLabel();
ilg.Emit(OpCodes.Ldloc, value);
ilg.Emit(OpCodes.Brtrue_S, nonNull);
ilg.Emit(OpCodes.Ldloc, packer);
ilg.Emit(OpCodes.Call, Methods.Packer_PackNull);
ilg.Emit(OpCodes.Br, end);
ilg.MarkLabel(nonNull);
}
if (!provider.TryEmitSerialiseCode(ilg, throwBlocks, errors, value, packer, contextLocal, context))
{
return(false);
}
ilg.MarkLabel(end);
}
return(true);
}