/// <summary>
/// Builds a serialization function for the Confluent wire format.
/// </summary>
/// <param name="id">
/// A schema ID to include in each serialized payload.
/// </param>
/// <param name="schema">
/// The schema to build the Avro serializer from.
/// </param>
/// <returns>
/// A function configured to serialize <typeparamref name="T" /> to an array of bytes.
/// </returns>
protected virtual Func <T, byte[]> Build(int id, Abstract.Schema schema)
{
var header = new byte[5];
Array.Copy(BitConverter.GetBytes(id), 0, header, 1, 4);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(header, 1, 4);
}
var inner = SerializerBuilder.BuildDelegateExpression <T>(schema);
var stream = Expression.Parameter(typeof(MemoryStream));
var value = inner.Parameters[0];
var streamConstructor = typeof(MemoryStream)
.GetConstructor(Type.EmptyTypes);
var writerConstructor = inner.Parameters[1].Type
.GetConstructor(new[] { typeof(Stream) });
var dispose = typeof(IDisposable)
.GetMethod(nameof(IDisposable.Dispose), Type.EmptyTypes);
var toArray = typeof(MemoryStream)
.GetMethod(nameof(MemoryStream.ToArray), Type.EmptyTypes);
var write = typeof(Stream)
.GetMethod(nameof(Stream.Write), new[] { typeof(byte[]), typeof(int), typeof(int) });
if (schema is BytesSchema)
{
inner = new WireFormatBytesSerializerRewriter(stream)
.VisitAndConvert(inner, GetType().Name);
}
var writer = Expression.Block(
new[] { stream },
Expression.Assign(stream, Expression.New(streamConstructor)),
Expression.TryFinally(
Expression.Block(
Expression.Call(
stream,
write,
Expression.Constant(header),
Expression.Constant(0),
Expression.Constant(header.Length)),
Expression.Invoke(
inner,
value,
Expression.New(writerConstructor, stream))),
Expression.Call(stream, dispose)),
Expression.Call(stream, toArray));
return(Expression.Lambda <Func <T, byte[]> >(writer, value).Compile());
}