Port Undo/Redo approach with a clean API

src/utils/DeleteSet.js

@@ -4,7 +4,8 @@ import {
   createID,
   getState,
   splitItem,
-  Item, AbstractStruct, StructStore, Transaction, ID // eslint-disable-line
+  iterateStructs,
+  Item, GC, StructStore, Transaction, ID // eslint-disable-line
 } from '../internals.js'
 
 import * as math from 'lib0/math.js'
@@ -47,29 +48,21 @@ export class DeleteSet {
 }
 
 /**
- * Iterate over all structs that were deleted.
- *
- * This function expects that the deletes structs are not merged. Hence, you can
- * probably only use it in type observes and `afterTransaction` events. But not
- * in `afterTransactionCleanup`.
+ * Iterate over all structs that the DeleteSet gc's.
  *
+ * @param {Transaction} transaction
  * @param {DeleteSet} ds
  * @param {StructStore} store
- * @param {function(AbstractStruct):void} f
+ * @param {function(GC|Item):void} f
  *
  * @function
  */
-export const iterateDeletedStructs = (ds, store, f) =>
+export const iterateDeletedStructs = (transaction, ds, store, f) =>
   ds.clients.forEach((deletes, clientid) => {
-    const structs = /** @type {Array<AbstractStruct>} */ (store.clients.get(clientid))
+    const structs = /** @type {Array<GC|Item>} */ (store.clients.get(clientid))
     for (let i = 0; i < deletes.length; i++) {
       const del = deletes[i]
-      let index = findIndexSS(structs, del.clock)
-      let struct
-      do {
-        struct = structs[index++]
-        f(struct)
-      } while (index < structs.length && structs[index].id.clock < del.clock + del.len)
+      iterateStructs(transaction, structs, del.clock, del.len, f)
     }
   })
 
@@ -143,6 +136,27 @@ export const sortAndMergeDeleteSet = ds => {
   })
 }
 
+/**
+ * @param {DeleteSet} ds1
+ * @param {DeleteSet} ds2
+ * @return {DeleteSet} A fresh DeleteSet
+ */
+export const mergeDeleteSets = (ds1, ds2) => {
+  const merged = new DeleteSet()
+  // Write all keys from ds1 to merged. If ds2 has the same key, combine the sets.
+  ds1.clients.forEach((dels1, client) =>
+    merged.clients.set(client, dels1.concat(ds2.clients.get(client) || []))
+  )
+  // Write all missing keys from ds2 to merged.
+  ds2.clients.forEach((dels2, client) => {
+    if (!merged.clients.has(client)) {
+      merged.clients.set(client, dels2)
+    }
+  })
+  sortAndMergeDeleteSet(merged)
+  return merged
+}
+
 /**
  * @param {DeleteSet} ds
  * @param {ID} id