DataRaft swift package

Sources/DataRaft/Classes/UserVersionStorage.swift

@@ -0,0 +1,66 @@
+import Foundation
+import DataLiteCore
+
+/// A database version storage that uses the `user_version` field.
+///
+/// This class implements ``VersionStorage`` by storing version information
+/// in the SQLite `PRAGMA user_version` field. It provides a lightweight,
+/// type-safe way to persist versioning data in a database.
+///
+/// The generic `Version` type must conform to both ``VersionRepresentable``
+/// and `RawRepresentable`, where `RawValue == UInt32`. This allows
+/// converting between stored integer values and semantic version types
+/// defined by the application.
+public final class UserVersionStorage<
+    Version: VersionRepresentable & RawRepresentable
+>: VersionStorage where Version.RawValue == UInt32 {
+    /// Errors related to reading or decoding the version.
+    public enum Error: Swift.Error {
+        /// The stored `user_version` could not be decoded into a valid `Version` case.
+        case invalidStoredVersion(UInt32)
+    }
+    
+    // MARK: - Inits
+    
+    /// Creates a new user version storage instance.
+    public init() {}
+    
+    // MARK: - Methods
+    
+    /// Returns the current version stored in the `user_version` field.
+    ///
+    /// This method reads the `PRAGMA user_version` value and attempts to
+    /// decode it into a valid `Version` value. If the stored value is not
+    /// recognized, it throws an error.
+    ///
+    /// - Parameter connection: The database connection.
+    /// - Returns: A decoded version value of type `Version`.
+    /// - Throws: ``Error/invalidStoredVersion(_:)`` if the stored value
+    ///   cannot be mapped to a valid `Version` instance.
+    public func getVersion(
+        _ connection: Connection
+    ) throws -> Version {
+        let raw = UInt32(bitPattern: connection.userVersion)
+        guard let version = Version(rawValue: raw) else {
+            throw Error.invalidStoredVersion(raw)
+        }
+        return version
+    }
+    
+    /// Stores the given version in the `user_version` field.
+    ///
+    /// This method updates the `PRAGMA user_version` field
+    /// with the raw `UInt32` value of the provided `Version`.
+    ///
+    /// - Parameters:
+    ///   - connection: The database connection.
+    ///   - version: The version to store.
+    public func setVersion(
+        _ connection: Connection,
+        _ version: Version
+    ) throws {
+        connection.userVersion = .init(
+            bitPattern: version.rawValue
+        )
+    }
+}