1 files changed, 79 insertions, 0 deletions
diff --git a/vendor/assets/javascripts/vue-virtual-scroller/src/mixins/IdState.js b/vendor/assets/javascripts/vue-virtual-scroller/src/mixins/IdState.js
new file mode 100644
index 00000000000..9b5bc57ab92
--- /dev/null
+++ b/vendor/assets/javascripts/vue-virtual-scroller/src/mixins/IdState.js
@@ -0,0 +1,79 @@
+import Vue from 'vue'
+
+export default function ({
+  idProp = vm => vm.item.id,
+} = {}) {
+  const store = {}
+  const vm = new Vue({
+    data () {
+      return {
+        store,
+      }
+    },
+  })
+
+  // @vue/component
+  return {
+    data () {
+      return {
+        idState: null,
+      }
+    },
+
+    created () {
+      this.$_id = null
+      if (typeof idProp === 'function') {
+        this.$_getId = () => idProp.call(this, this)
+      } else {
+        this.$_getId = () => this[idProp]
+      }
+      this.$watch(this.$_getId, {
+        handler (value) {
+          this.$nextTick(() => {
+            this.$_id = value
+          })
+        },
+        immediate: true,
+      })
+      this.$_updateIdState()
+    },
+
+    beforeUpdate () {
+      this.$_updateIdState()
+    },
+
+    methods: {
+      /**
+       * Initialize an idState
+       * @param {number|string} id Unique id for the data
+       */
+      $_idStateInit (id) {
+        const factory = this.$options.idState
+        if (typeof factory === 'function') {
+          const data = factory.call(this, this)
+          vm.$set(store, id, data)
+          this.$_id = id
+          return data
+        } else {
+          throw new Error('[mixin IdState] Missing `idState` function on component definition.')
+        }
+      },
+
+      /**
+       * Ensure idState is created and up-to-date
+       */
+      $_updateIdState () {
+        const id = this.$_getId()
+        if (id == null) {
+          console.warn(`No id found for IdState with idProp: '${idProp}'.`)
+        }
+        if (id !== this.$_id) {
+          if (!store[id]) {
+            this.$_idStateInit(id)
+          }
+          this.idState = store[id]
+        }
+      },
+    },
+  }
+}