restructuring the project

src/structs/ItemFormat.js

@@ -0,0 +1,56 @@
+/**
+ * @module structs
+ */
+
+import { Item } 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 ItemFormat extends Item {
+  constructor () {
+    super()
+    this.key = null
+    this.value = null
+  }
+  _copy (undeleteChildren, copyPosition) {
+    let struct = super._copy()
+    struct.key = this.key
+    struct.value = this.value
+    return struct
+  }
+  get _length () {
+    return 1
+  }
+  get _countable () {
+    return false
+  }
+  /**
+   * @param {Y} y
+   * @param {decoding.Decoder} decoder
+   */
+  _fromBinary (y, decoder) {
+    const missing = super._fromBinary(y, decoder)
+    this.key = decoding.readVarString(decoder)
+    this.value = JSON.parse(decoding.readVarString(decoder))
+    return missing
+  }
+  /**
+   * @param {encoding.Encoder} encoder
+   */
+  _toBinary (encoder) {
+    super._toBinary(encoder)
+    encoding.writeVarString(encoder, this.key)
+    encoding.writeVarString(encoder, JSON.stringify(this.value))
+  }
+  /**
+   * Transform this YXml Type to a readable format.
+   * Useful for logging as all Items and Delete implement this method.
+   *
+   * @private
+   */
+  _logString () {
+    return stringify.logItemHelper('ItemFormat', this, `key:${JSON.stringify(this.key)},value:${JSON.stringify(this.value)}`)
+  }
+}