implement when-handler

src/Persistence.js

@@ -47,12 +47,33 @@ export default class AbstractPersistence {
   }
   deinit (y) {
     this.ys.delete(y)
+    y.persistence = null
   }
 
   destroy () {
     this.ys = null
   }
 
+  /**
+   * Remove all persisted data that belongs to a room.
+   * Automatically destroys all Yjs all Yjs instances that persist to
+   * the room. If `destroyYjsInstances = false` the persistence functionality
+   * will be removed from the Yjs instances.
+   *
+   * ** Must be overwritten! **
+   */
+  removePersistedData (room, destroyYjsInstances = true) {
+    this.ys.forEach((cnf, y) => {
+      if (y.room === room) {
+        if (destroyYjsInstances) {
+          y.destroy()
+        } else {
+          this.deinit(y)
+        }
+      }
+    })
+  }
+
   /* overwrite */
   saveUpdate (buffer) {
   }
@@ -77,17 +98,17 @@ export default class AbstractPersistence {
       y.transact(function () {
         if (model != null) {
           fromBinary(y, new BinaryDecoder(new Uint8Array(model)))
-          y._setContentReady()
         }
         if (updates != null) {
           for (let i = 0; i < updates.length; i++) {
             integrateRemoteStructs(y, new BinaryDecoder(new Uint8Array(updates[i])))
-            y._setContentReady()
           }
         }
       })
+      y.emit('persistenceReady')
     })
   }
+
   /* overwrite */
   persist (y) {
     return toBinary(y).createBuffer()

src/Util/NamedEventHandler.js

@@ -1,6 +1,7 @@
 export default class NamedEventHandler {
   constructor () {
     this._eventListener = new Map()
+    this._stateListener = new Map()
   }
   _getListener (name) {
     let listeners = this._eventListener.get(name)
@@ -21,6 +22,20 @@ export default class NamedEventHandler {
     let listeners = this._getListener(name)
     listeners.on.add(f)
   }
+  _initStateListener (name) {
+    let state = this._stateListener.get(name)
+    if (state === undefined) {
+      state = {}
+      state.promise = new Promise(function (resolve) {
+        state.resolve = resolve
+      })
+      this._stateListener.set(name, state)
+    }
+    return state
+  }
+  when (name) {
+    return this._initStateListener(name).promise
+  }
   off (name, f) {
     if (name == null || f == null) {
       throw new Error('You must specify event name and function!')
@@ -32,6 +47,7 @@ export default class NamedEventHandler {
     }
   }
   emit (name, ...args) {
+    this._initStateListener(name).resolve()
     const listener = this._eventListener.get(name)
     if (listener !== undefined) {
       listener.on.forEach(f => f.apply(null, args))

src/Y.js

@@ -62,6 +62,15 @@ export default class Y extends NamedEventHandler {
       this.emit('content')
     }
   }
+  whenContentReady () {
+    if (this._contentReady) {
+      return Promise.resolve()
+    } else {
+      return new Promise(resolve => {
+        this.once('content', resolve)
+      })
+    }
+  }
   _beforeChange () {}
   transact (f, remote = false) {
     let initialCall = this._transaction === null