5. SmartCodable Performance

    // 减少动态派发开销，is 检查是编译时静态行为，比 as? 动态转换更高效。
fileprivate func didFinishMapping<T>(_ decodeValue: T) -> T {
    // Properties wrapped by property wrappers don't conform to SmartDecodable protocol.
    // Here we use PostDecodingHookable as an intermediary layer for processing.
    
    
    // 减少动态派发开销，is 检查是编译时静态行为，比 as? 动态转换更高效。
    guard T.self is SmartDecodable.Type else { return decodeValue }
    
    if var value = decodeValue as? SmartDecodable {
        value.didFinishMapping()
        if let temp = value as? T { return temp }
    } else if let value = decodeValue as? PostDecodingHookable {
        if let temp = value.wrappedValueDidFinishMapping() as? T {
            return temp
        }
    }
    return decodeValue
}

用到再换成，避免无用换成。 /// Creates and stores a snapshot of initial values for a Decodable type /// - Parameter type: The Decodable type to cache func cacheSnapshot(for type: T.Type) { if let object = type as? SmartDecodable.Type {

        let snapshot = DecodingSnapshot()
        // [initialValues] Lazy initialization:
        // Generate initial values via reflection only when first accessed,
        // using the recorded objectType to optimize parsing performance.
        snapshot.objectType = object
        snapshots.append(snapshot)
    }
}