main.scala.smithy4s.protobuf.internals.WriteNode.scala Maven / Gradle / Ivy
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/*
* Copyright 2021-2024 Disney Streaming
*
* Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://disneystreaming.github.io/TOST-1.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package smithy4s.protobuf.internals
import com.google.protobuf.CodedOutputStream
/** Unfortunately, the process of serialisation requires us to store the
* serialised size somewhere to avoid recomputing it, as it's involved not only
* in the computation of the size of the whole message, but also as a local
* header in case of length-delimited bits.
*
* The `ProtoNode` is a meant to store this size as well as the function that
* writes a field to a protobuf-specialised output stream.
*
* ScalaPB (and probably other protobuf libraries) manages to avoid this extra
* allocation by having mutable variables in the generated case-classes to
* store this information, thus evading the extra allocation at the cost of
* highly specialised data models.
*/
private[internals] abstract class WriteNode(val serialisedSize: Int) {
def write(os: CodedOutputStream): Unit
}
private[internals] object WriteNode {
val empty: WriteNode = new WriteNode(0) {
def write(os: CodedOutputStream): Unit = ()
}
}