restructuring the project

src/structs/ItemString.js

@@ -0,0 +1,61 @@
+/**
+ * @module structs
+ */
+
+import { Item, splitHelper } from './Item.js'
+import * as stringify from 'y-protocols/utils/structStringify.js'
+import * as encoding from 'funlib/encoding.js'
+import * as decoding from 'funlib/decoding.js'
+import { Y } from '../utils/Y.js' // eslint-disable-line
+
+export class ItemString extends Item {
+  constructor () {
+    super()
+    this._content = null
+  }
+  _copy () {
+    let struct = super._copy()
+    struct._content = this._content
+    return struct
+  }
+  get _length () {
+    return this._content.length
+  }
+  /**
+   * @param {Y} y
+   * @param {decoding.Decoder} decoder
+   */
+  _fromBinary (y, decoder) {
+    let missing = super._fromBinary(y, decoder)
+    this._content = decoding.readVarString(decoder)
+    return missing
+  }
+  /**
+   * @param {encoding.Encoder} encoder
+   */
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    encoding.writeVarString(encoder, this._content)
+  }
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return stringify.logItemHelper('ItemString', this, `content:"${this._content}"`)
+  }
+  _splitAt (y, diff) {
+    if (diff === 0) {
+      return this
+    } else if (diff >= this._length) {
+      return this._right
+    }
+    let item = new ItemString()
+    item._content = this._content.slice(diff)
+    this._content = this._content.slice(0, diff)
+    splitHelper(y, this, item, diff)
+    return item
+  }
+}