1 files changed, 56 insertions, 0 deletions
diff --git a/Other/AstarPathfindingDemo/Packages/com.arongranberg.astar/PackageTools/Migrations.cs b/Other/AstarPathfindingDemo/Packages/com.arongranberg.astar/PackageTools/Migrations.cs
new file mode 100644
index 0000000..4e0d2cb
--- /dev/null
+++ b/Other/AstarPathfindingDemo/Packages/com.arongranberg.astar/PackageTools/Migrations.cs
@@ -0,0 +1,56 @@
+namespace Pathfinding.Serialization {
+	/// <summary>
+	/// Helper struct for handling serialization backwards compatibility.
+	///
+	/// It stores which migrations have been completed as a bitfield.
+	/// </summary>
+	public struct Migrations {
+		/// <summary>Bitfield of all migrations that have been run</summary>
+		internal int finishedMigrations;
+		/// <summary>
+		/// Bitfield of all migrations that the component supports.
+		/// A newly created component will be initialized with this value.
+		/// </summary>
+		internal int allMigrations;
+		internal bool ignore;
+
+		/// <summary>A special migration flag which is used to mark that the version has been migrated to the bitfield format, from the legacy linear version format</summary>
+		const int MIGRATE_TO_BITFIELD = 1 << 30;
+
+		public bool IsLegacyFormat => (finishedMigrations & MIGRATE_TO_BITFIELD) == 0;
+		public int LegacyVersion => finishedMigrations;
+
+		public Migrations(int value) {
+			this.finishedMigrations = value;
+			allMigrations = MIGRATE_TO_BITFIELD;
+			ignore = false;
+		}
+
+		public bool TryMigrateFromLegacyFormat (out int legacyVersion) {
+			legacyVersion = finishedMigrations;
+			if (IsLegacyFormat) {
+				this = new Migrations(MIGRATE_TO_BITFIELD);
+				return true;
+			} else return false;
+		}
+
+		public void MarkMigrationFinished (int flag) {
+			if (IsLegacyFormat) throw new System.InvalidOperationException("Version must first be migrated to the bitfield format");
+			finishedMigrations |= flag;
+		}
+
+		public bool AddAndMaybeRunMigration (int flag, bool filter = true) {
+			if ((flag & MIGRATE_TO_BITFIELD) != 0) throw new System.ArgumentException("Cannot use the MIGRATE_TO_BITFIELD flag when adding a migration");
+			allMigrations |= flag;
+			if (filter) {
+				var res = (finishedMigrations & flag) != flag;
+				MarkMigrationFinished(flag);
+				return res;
+			} else return false;
+		}
+
+		public void IgnoreMigrationAttempt () {
+			ignore = true;
+		}
+	}
+}