perf: Stop using tagger encoder

api/avro4k-core.api

@@ -158,6 +158,11 @@ public final class com/github/avrokotlin/avro4k/decoder/AvroDecoder$DefaultImpls
 	public static fun decodeSerializableValue (Lcom/github/avrokotlin/avro4k/decoder/AvroDecoder;Lkotlinx/serialization/DeserializationStrategy;)Ljava/lang/Object;
 }
 
+public final class com/github/avrokotlin/avro4k/decoder/AvroDecoderKt {
+	public static final fun decodeResolvingUnion (Lcom/github/avrokotlin/avro4k/decoder/AvroDecoder;Lorg/apache/avro/Schema;Lkotlin/jvm/functions/Function0;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
+	public static final fun resolveUnion (Lcom/github/avrokotlin/avro4k/decoder/AvroDecoder;Lorg/apache/avro/Schema;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
+}
+
 public abstract interface class com/github/avrokotlin/avro4k/encoder/AvroEncoder : kotlinx/serialization/encoding/Encoder {
 	public abstract fun getCurrentWriterSchema ()Lorg/apache/avro/Schema;
 }
@@ -167,6 +172,22 @@ public final class com/github/avrokotlin/avro4k/encoder/AvroEncoder$DefaultImpls
 	public static fun encodeSerializableValue (Lcom/github/avrokotlin/avro4k/encoder/AvroEncoder;Lkotlinx/serialization/SerializationStrategy;Ljava/lang/Object;)V
 }
 
+public final class com/github/avrokotlin/avro4k/encoder/AvroEncoderKt {
+	public static final fun encodeResolvingUnion (Lcom/github/avrokotlin/avro4k/encoder/AvroEncoder;Lorg/apache/avro/Schema;Lkotlin/jvm/functions/Function0;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
+	public static final fun resolveUnion (Lcom/github/avrokotlin/avro4k/encoder/AvroEncoder;Lorg/apache/avro/Schema;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
+}
+
+public abstract interface class com/github/avrokotlin/avro4k/encoder/UnionEncoder : com/github/avrokotlin/avro4k/encoder/AvroEncoder {
+	public abstract fun getCurrentWriterSchema ()Lorg/apache/avro/Schema;
+	public abstract fun selectUnionIndex (I)V
+	public abstract fun setCurrentWriterSchema (Lorg/apache/avro/Schema;)V
+}
+
+public final class com/github/avrokotlin/avro4k/encoder/UnionEncoder$DefaultImpls {
+	public static fun beginCollection (Lcom/github/avrokotlin/avro4k/encoder/UnionEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;I)Lkotlinx/serialization/encoding/CompositeEncoder;
+	public static fun encodeSerializableValue (Lcom/github/avrokotlin/avro4k/encoder/UnionEncoder;Lkotlinx/serialization/SerializationStrategy;Ljava/lang/Object;)V
+}
+
 public abstract interface class com/github/avrokotlin/avro4k/schema/FieldNamingStrategy {
 	public static final field Builtins Lcom/github/avrokotlin/avro4k/schema/FieldNamingStrategy$Builtins;
 	public abstract fun resolve (Lkotlinx/serialization/descriptors/SerialDescriptor;I)Ljava/lang/String;

src/main/kotlin/com/github/avrokotlin/avro4k/Avro.kt

@@ -4,7 +4,6 @@ import com.github.avrokotlin.avro4k.decoder.AvroValueDecoder
 import com.github.avrokotlin.avro4k.encoder.AvroValueEncoder
 import com.github.avrokotlin.avro4k.internal.EnumResolver
 import com.github.avrokotlin.avro4k.internal.RecordResolver
-import com.github.avrokotlin.avro4k.internal.UnionResolver
 import com.github.avrokotlin.avro4k.schema.FieldNamingStrategy
 import com.github.avrokotlin.avro4k.schema.ValueVisitor
 import com.github.avrokotlin.avro4k.serializer.BigDecimalSerializer
@@ -49,7 +48,6 @@ public sealed class Avro(
     private val schemaCache: MutableMap<SerialDescriptor, Schema> = WeakIdentityHashMap()
 
     internal val recordResolver = RecordResolver(this)
-    internal val unionResolver = UnionResolver()
     internal val enumResolver = EnumResolver()
 
     public companion object Default : Avro(

src/main/kotlin/com/github/avrokotlin/avro4k/decoder/AvroDecoder.kt

@@ -26,4 +26,40 @@ public interface AvroDecoder : Decoder {
      */
     @ExperimentalSerializationApi
     public fun decodeValue(): Any
+}
+
+@ExperimentalSerializationApi
+public inline fun <T : Any> AvroDecoder.decodeResolvingUnion(
+    error: () -> Throwable,
+    resolver: (Schema) -> (() -> T)?,
+): T {
+    val schema = currentWriterSchema
+    return decodeResolvingUnion(schema, error, resolver)
+}
+
+@PublishedApi
+internal inline fun <T : Any> AvroDecoder.decodeResolvingUnion(
+    schema: Schema,
+    error: () -> Throwable,
+    resolver: (Schema) -> (() -> T)?,
+): T {
+    return if (schema.type == Schema.Type.UNION) {
+        resolveUnion(schema, resolver)
+    } else {
+        resolver(schema)?.invoke()
+    } ?: throw error()
+}
+
+@PublishedApi
+internal inline fun <T> AvroDecoder.resolveUnion(
+    schema: Schema,
+    resolver: (Schema) -> (() -> T)?,
+): T? {
+    for (index in schema.types.indices) {
+        val subSchema = schema.types[index]
+        resolver(subSchema)?.let {
+            return it.invoke()
+        }
+    }
+    return null
 }