Refactoring II.

- Filter by date range
- SyncUpdate tasks run fully asynchronous in background
- Move tableView manipulations into FilterPipelineDelegate
- Move SyncUpdate notification into SyncUpdateDelegate
- Fix: sync cache before persisting a recording
- Restructuring GroupedDomainDataSource
- Performance: db logs queries use rowids instead of timestamps
- Add 'now' button to DatePickerAlert

main/Extensions/Generic.swift

@@ -27,15 +27,34 @@ extension UIEdgeInsets {
 	}
 }
 
-infix operator =? : ComparisonPrecedence
+precedencegroup CompareAssignPrecedence {
+	assignment: true
+	associativity: left
+	higherThan: ComparisonPrecedence
+}
+
+infix operator <-? : CompareAssignPrecedence
+infix operator <-/ : CompareAssignPrecedence
 extension Equatable {
-	/// Assign a new value to `lhs` if the `newValue` differs from the previous value. Return whether the new value was set.
+	/// Assign a new value to `lhs` if `newValue` differs from the previous value. Return `false` if they are equal.
 	/// - Returns: `true` if `lhs` was overwritten with another value
-	static func =?(lhs: inout Self, newValue: Self) -> Bool {
+	static func <-?(lhs: inout Self, newValue: Self) -> Bool {
 		if lhs != newValue {
 			lhs = newValue
 			return true
 		}
 		return false
 	}
+	
+	/// Assign a new value to `lhs` if `newValue` differs from the previous value.
+	/// Return tuple with both values. Or `nil` if they are equal.
+	/// - Returns: `nil` if `previousValue == newValue`
+	static func <-/(lhs: inout Self, newValue: Self) -> (previousValue: Self, newValue: Self)? {
+		let previousValue = lhs
+		if previousValue != newValue {
+			lhs = newValue
+			return (previousValue, newValue)
+		}
+		return nil
+	}
 }