private (string prepareBlock, string serializeBlock) GetUnionSerializeBlocks(int index, TableMemberModel memberModel)
{
UnionTypeModel unionModel = (UnionTypeModel)memberModel.ItemTypeModel;
string valueVariableName = $"index{index}Value";
string discriminatorOffsetVariableName = $"index{index}DiscriminatorOffset";
string valueOffsetVariableName = $"index{index}ValueOffset";
string discriminatorValueVariableName = $"index{index}Discriminator";
string prepareBlock =
$@"
var {valueVariableName} = item.{memberModel.PropertyInfo.Name};
int {discriminatorOffsetVariableName} = 0;
int {valueOffsetVariableName} = 0;
byte {discriminatorValueVariableName} = 0;
if ({valueVariableName} != null && {valueVariableName}.Discriminator != 0)
{{
{discriminatorValueVariableName} = {valueVariableName}.Discriminator;
{discriminatorOffsetVariableName} = currentOffset;
vtable.{nameof(VTableBuilder.SetOffset)}({index}, currentOffset - tableStart);
currentOffset++;
currentOffset += {CSharpHelpers.GetFullMethodName(ReflectedMethods.SerializationHelpers_GetAlignmentErrorMethod)}(currentOffset, sizeof(uint));
{valueOffsetVariableName} = currentOffset;
vtable.{nameof(VTableBuilder.SetOffset)}({index + 1}, currentOffset - tableStart);
currentOffset += sizeof(uint);
}}";
List <string> switchCases = new List <string>();
for (int i = 0; i < unionModel.UnionElementTypeModel.Length; ++i)
{
var elementModel = unionModel.UnionElementTypeModel[i];
var unionIndex = i + 1;
string structAdjustment = string.Empty;
if (elementModel.SchemaType == FlatBufferSchemaType.Struct)
{
// Structs are generally written in-line, with the exception of unions.
// So, we need to do the normal allocate space dance here, since we're writing
// a pointer to a struct.
structAdjustment =
$@"
var writeOffset = context.{nameof(SerializationContext.AllocateSpace)}({elementModel.InlineSize}, {elementModel.Alignment});
writer.{nameof(SpanWriter.WriteUOffset)}(span, {valueOffsetVariableName}, writeOffset, context);
{valueOffsetVariableName} = writeOffset;";
}
string @case =
$@"
case {unionIndex}:
{{
{structAdjustment}
{this.GetSerializeInvocation(elementModel.ClrType, $"{valueVariableName}.Item{unionIndex}", valueOffsetVariableName)}
}}
break;";
switchCases.Add(@case);
}
string serializeBlock =
$@"
if ({discriminatorOffsetVariableName} != 0)
{{
{this.GetSerializeInvocation(typeof(byte), discriminatorValueVariableName, discriminatorOffsetVariableName)}
switch ({discriminatorValueVariableName})
{{
{string.Join("\r\n", switchCases)}
default: throw new InvalidOperationException(""Unexpected"");
}}
}}";
return(prepareBlock, serializeBlock);
}