WIP: Make AdaptorOperation a struct

Since an adaptor operation has a completion closure which is reset
when it got performed, a set of methods take inout's now. Also the
resultRow value is being updated.
Note that the `DatabaseChannel` *does* make use of that to update the
related DatabaseOperation objects.

Sources/ZeeQL/Access/AdaptorChannel.swift

@@ -29,7 +29,7 @@ public protocol AdaptorChannel : AdaptorQueryType, ModelNameMapper {
   func begin()    throws
   func commit()   throws
   func rollback() throws
-  var isTransactionInProgress : Bool { get }
+  var  isTransactionInProgress : Bool { get }
 
 
   // MARK: - Reflection
@@ -45,8 +45,8 @@ public protocol AdaptorChannel : AdaptorQueryType, ModelNameMapper {
 
   // MARK: - Adaptor Operations
 
-  func performAdaptorOperations(_ ops : [ AdaptorOperation ]) throws
-  func performAdaptorOperation (_ op  : AdaptorOperation)     throws
+  func performAdaptorOperations(_ ops : inout [ AdaptorOperation ]) throws
+  func performAdaptorOperation (_ op  : inout AdaptorOperation)     throws
 
 
   // MARK: - Operations
@@ -184,7 +184,7 @@ public extension AdaptorChannel {
    * - parameters:
    *   - ops: the array of AdaptorOperation's to be performed
    */
-  func performAdaptorOperations(_ ops: [ AdaptorOperation ]) throws {
+  func performAdaptorOperations(_ ops: inout [ AdaptorOperation ]) throws {
     // TBD: we should probably open a transaction if count > 1? Or is this the
     //      responsibility of the user?
 
@@ -202,8 +202,8 @@ public extension AdaptorChannel {
     if didOpenTx { try begin() }
 
     do {
-      for op in ops {
-        try performAdaptorOperation(op)
+      for idx in ops.indices {
+        try performAdaptorOperation(&ops[idx])
       }
     }
     catch {
@@ -222,8 +222,8 @@ public extension AdaptorChannel {
    *   - op: the ``AdaptorOperation`` to be performed
    */
   @inlinable
-  func performAdaptorOperation(_ op: AdaptorOperation) throws {
-    let affectedRows = try performAdaptorOperationN(op)
+  func performAdaptorOperation(_ op: inout AdaptorOperation) throws {
+    let affectedRows = try performAdaptorOperationN(&op)
     guard affectedRows == 1 else {
       throw AdaptorChannelError.OperationDidNotAffectOne
     }
@@ -241,7 +241,7 @@ public extension AdaptorChannel {
    * - Parameters:
    *   - op: the ``AdaptorOperation`` to be performed
    */
-  func performAdaptorOperationN(_ op: AdaptorOperation) throws -> Int {
+  func performAdaptorOperationN(_ op: inout AdaptorOperation) throws -> Int {
     // TBD: we might want to move evaluation to this method and make
     // updateValuesInRows..() etc create AdaptorOperation's. This might
     // easen the creation of non-SQL adaptors.

Sources/ZeeQL/Access/AdaptorOperation.swift

@@ -11,7 +11,7 @@
  * an INSERT. The object keeps all the relevant information to calculate the
  * SQL for the operation.
  */
-public class AdaptorOperation: Comparable, EquatableType, SmartDescription {
+public struct AdaptorOperation: Comparable, EquatableType, SmartDescription {
   // Note: an object because we also return values using this
 
   @inlinable
@@ -61,7 +61,7 @@ public class AdaptorOperation: Comparable, EquatableType, SmartDescription {
   public var resultRow       : AdaptorRow?
 
   /// Run when the operation did complete
-  open   var completionBlock : (() -> ())?
+  public var completionBlock : (() -> ())?
 
   @inlinable
   public init(entity: Entity) {
@@ -122,7 +122,7 @@ public class AdaptorOperation: Comparable, EquatableType, SmartDescription {
 
     if bq == q { return self } // no change
 
-    let ao = AdaptorOperation(self) // copy
+    var ao = AdaptorOperation(self) // copy
     ao.qualifier = bq
     return ao
   }

Sources/ZeeQL/Access/DatabaseChannel.swift

@@ -861,14 +861,19 @@ open class DatabaseChannelBase {
 
     /* turn db ops into adaptor ops */
 
-    let aops = try adaptorOperationsForDatabaseOperations(ops)
+    var aops = try adaptorOperationsForDatabaseOperations(ops)
     guard !aops.isEmpty else { return } /* nothing to do */
 
     /* perform adaptor ops */
 
     var didOpenChannel = false
-    if adaptorChannel == nil {
+    let adaptorChannel : AdaptorChannel
+    if let c = self.adaptorChannel {
+      adaptorChannel = c
+    }
+    else {
       adaptorChannel = try acquireChannel()
+      self.adaptorChannel = adaptorChannel
       didOpenChannel = true
     }
     defer {
@@ -879,7 +884,7 @@ open class DatabaseChannelBase {
 
     // Transactions: The `AdaptorChannel` opens a transaction if there is more
     // than one operation. Also: the `Database` embeds it into a TX too.
-    try adaptorChannel!.performAdaptorOperations(aops)
+    try adaptorChannel.performAdaptorOperations(&aops)
 
 
     // OK, the database operations have been successful. Now we need to handle
@@ -971,7 +976,7 @@ open class DatabaseChannelBase {
 
     for op in ops {
       let entity = op.entity
-      let aop    = AdaptorOperation(entity: entity)
+      var aop    = AdaptorOperation(entity: entity)
 
       var dbop = op.databaseOperator
       if case .none = op.databaseOperator {