restructuring the project

src/structs/Delete.js

@@ -0,0 +1,104 @@
+/**
+ * @module structs
+ */
+
+import { getStructReference } from 'y-protocols/sync.js'
+import * as ID from '../utils/ID.js'
+import { writeStructToTransaction } from '../utils/structEncoding.js'
+import * as decoding from 'funlib/decoding.js'
+import * as encoding from 'funlib/encoding.js'
+// import { Item } from './Item.js' // eslint-disable-line
+// import { Y } from '../utils/Y.js' // eslint-disable-line
+import { deleteItemRange } from '../utils/structManipulation.js'
+import * as stringify from 'y-protocols/utils/structStringify.js'
+
+/**
+ * @private
+ * A Delete change is not a real Item, but it provides the same interface as an
+ * Item. The only difference is that it will not be saved in the ItemStore
+ * (OperationStore), but instead it is safed in the DeleteStore.
+ */
+export class Delete {
+  constructor () {
+    /**
+     * @type {ID.ID}
+     */
+    this._targetID = null
+    /**
+     * @type {Item}
+     */
+    this._target = null
+    this._length = null
+  }
+
+  /**
+   * @private
+   * Read the next Item in a Decoder and fill this Item with the read data.
+   *
+   * This is called when data is received from a remote peer.
+   *
+   * @param {Y} y The Yjs instance that this Item belongs to.
+   * @param {decoding.Decoder} decoder The decoder object to read data from.
+   */
+  _fromBinary (y, decoder) {
+    // TODO: set target, and add it to missing if not found
+    // There is an edge case in p2p networks!
+    /**
+     * @type {any}
+     */
+    const targetID = ID.decode(decoder)
+    this._targetID = targetID
+    this._length = decoding.readVarUint(decoder)
+    if (y.os.getItem(targetID) === null) {
+      return [targetID]
+    } else {
+      return []
+    }
+  }
+
+  /**
+   * @private
+   * Transform the properties of this type to binary and write it to an
+   * BinaryEncoder.
+   *
+   * This is called when this Item is sent to a remote peer.
+   *
+   * @param {encoding.Encoder} encoder The encoder to write data to.
+   */
+  _toBinary (encoder) {
+    encoding.writeUint8(encoder, getStructReference(this.constructor))
+    this._targetID.encode(encoder)
+    encoding.writeVarUint(encoder, this._length)
+  }
+
+  /**
+   * @private
+   * Integrates this Item into the shared structure.
+   *
+   * This method actually applies the change to the Yjs instance. In the case of
+   * Delete it marks the delete target as deleted.
+   *
+   * * If created remotely (a remote user deleted something),
+   *   this Delete is applied to all structs in id-range.
+   * * If created lokally (e.g. when y-array deletes a range of elements),
+   *   this struct is broadcasted only (it is already executed)
+   */
+  _integrate (y, locallyCreated = false) {
+    if (!locallyCreated) {
+      // from remote
+      const id = this._targetID
+      deleteItemRange(y, id.user, id.clock, this._length, false)
+    }
+    writeStructToTransaction(y._transaction, this)
+  }
+
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return `Delete - target: ${stringify.stringifyID(this._targetID)}, len: ${this._length}`
+  }
+}