improved granularity of prosemirror binding

structs/GC.js

@@ -19,6 +19,10 @@ export class GC {
     this._length = 0
   }
 
+  get _redone () {
+    return null
+  }
+
   get _deleted () {
     return true
   }

structs/Item.js

@@ -113,6 +113,30 @@ export class Item {
     this._redone = null
   }
 
+  /**
+   * Returns the next non-deleted item
+   * @private
+   */
+  get _next () {
+    let n = this._right
+    while (n !== null && n._deleted) {
+      n = n._right
+    }
+    return n
+  }
+
+  /**
+   * Returns the previous non-deleted item
+   * @private
+   */
+  get _prev () {
+    let n = this._left
+    while (n !== null && n._deleted) {
+      n = n._left
+    }
+    return n
+  }
+
   /**
    * Creates an Item with the same effect as this Item (without position effect)
    *
@@ -127,7 +151,7 @@ export class Item {
    * Redoes the effect of this operation.
    *
    * @param {Y} y The Yjs instance.
-   * @param {Array<Item>} redoitems
+   * @param {Set<Item>} redoitems
    *
    * @private
    */

structs/Type.js

@@ -57,6 +57,17 @@ export class Type extends Item {
     this._deepEventHandler = new EventHandler()
   }
 
+  /**
+   * The first non-deleted item
+   */
+  get _first () {
+    let n = this._start
+    while (n !== null && n._deleted) {
+      n = n._right
+    }
+    return n
+  }
+
   /**
    * Compute the path from this type to the specified target.
    *