feat: undo manager

Author: Leeeon233

README.md

@@ -72,7 +72,6 @@ let subId = doc.subscribeRoot{ diffEvent in
 doc.unsubscribe(subId: id)
 
 // export updates or snapshot
-
 let doc2 = LoroDoc()
 let snapshot = doc.exportSnapshot()
 let updates = doc.exportFrom(vv: VersionVector())

Sources/Loro/Loro.swift

@@ -8,3 +8,48 @@
 
 
 import Foundation
+
+
+class ClosureOnPush: OnPush {
+    private let closure: (UndoOrRedo, CounterSpan) ->UndoItemMeta
+
+    public init(closure: @escaping (UndoOrRedo, CounterSpan) ->UndoItemMeta) {
+        self.closure = closure
+    }
+
+    public func onPush(undoOrRedo: UndoOrRedo, span: CounterSpan) -> UndoItemMeta{
+        closure(undoOrRedo, span)
+    }
+}
+
+class ClosureOnPop: OnPop {
+    private let closure: (UndoOrRedo, CounterSpan,UndoItemMeta)->Void
+
+    public init(closure: @escaping (UndoOrRedo, CounterSpan,UndoItemMeta)->Void) {
+        self.closure = closure
+    }
+
+    public func onPop(undoOrRedo: UndoOrRedo, span: CounterSpan, undoMeta: UndoItemMeta) {
+        closure(undoOrRedo, span, undoMeta)
+    }
+}
+
+extension UndoManager{
+    public func setOnPush(callback: ((UndoOrRedo, CounterSpan) ->UndoItemMeta)?){
+        if let onPush = callback{
+            let closureOnPush = ClosureOnPush(closure: onPush)
+            self.setOnPush(onPush: closureOnPush)
+        }else{
+            self.setOnPush(onPush: nil)
+        }
+    }
+    
+    public func setOnPop(callback: ( (UndoOrRedo, CounterSpan,UndoItemMeta)->Void)?){
+        if let onPop = callback{
+            let closureOnPop = ClosureOnPop(closure: onPop)
+            self.setOnPop(onPop: closureOnPop)
+        }else{
+            self.setOnPop(onPop: nil)
+        }
+    }
+}