swift-protobuf/Sources/SwiftProtobuf/UnknownStorage.swift

// Sources/SwiftProtobuf/UnknownStorage.swift - Handling unknown fields
//
// Copyright (c) 2014 - 2016 Apple Inc. and the project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See LICENSE.txt for license information:
// https://github.com/apple/swift-protobuf/blob/main/LICENSE.txt
//
// -----------------------------------------------------------------------------
///
/// Proto2 binary coding requires storing and recoding of unknown fields.
/// This simple support class handles that requirement.  A property of this type
/// is compiled into every proto2 message.
///
// -----------------------------------------------------------------------------

import Foundation

/// Contains any unknown fields in a decoded message; that is, fields that were
/// sent on the wire but were not recognized by the generated message
/// implementation or were valid field numbers but with mismatching wire
/// formats (for example, a field encoded as a varint when a fixed32 integer
/// was expected).
public struct UnknownStorage: Equatable, @unchecked Sendable {
    // Once swift(>=5.9) the '@unchecked' can be removed, it is needed for Data in
    // linux builds.

    /// The raw protocol buffer binary-encoded bytes that represent the unknown
    /// fields of a decoded message.
    public private(set) var data = Data()

    public init() {}

    internal mutating func append(protobufData: Data) {
        data.append(protobufData)
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        if !data.isEmpty {
            try visitor.visitUnknown(bytes: data)
        }
    }
}