implement RealmStore

routes/_components/pseudoVirtualList/PseudoVirtualList.html

@@ -29,7 +29,7 @@
   export default {
     oncreate() {
       mark('PseudoVirtualList oncreate()')
-      this.store.set({currentRealm: this.get('realm')})
+      this.store.setCurrentRealm(this.get('realm'))
 
       // When re-rendering, assume all items are non-intersecting until told otherwise.
       // We already have the heights cached.

routes/_components/pseudoVirtualList/pseudoVirtualListStore.js

@@ -1,21 +1,14 @@
-import { Store } from 'svelte/store.js'
+import { RealmStore } from '../../_utils/RealmStore'
 
-class PseudoVirtualListStore extends Store {
-  setForRealm(obj) {
-    let realmName = this.get('currentRealm')
-    let realms = this.get('realms') || {}
-    realms[realmName] = Object.assign(realms[realmName] || {}, obj)
-    this.set({realms: realms})
+class PseudoVirtualListStore extends RealmStore {
+  constructor(state) {
+    super(state, /* maxSize */ 10)
   }
 }
 
 const pseudoVirtualListStore = new PseudoVirtualListStore()
 
-pseudoVirtualListStore.compute('intersectionStates',
-    ['realms', 'currentRealm'],
-    (realms, currentRealm) => {
-  return (realms && realms[currentRealm] && realms[currentRealm].intersectionStates) || {}
-})
+pseudoVirtualListStore.computeForRealm('intersectionStates', {})
 
 if (process.browser && process.env.NODE_NODE !== 'production') {
   window.pseudoVirtualListStore = pseudoVirtualListStore

routes/_components/virtualList/VirtualListContainer.html

@@ -17,8 +17,7 @@
     oncreate() {
       mark('onCreate VirtualListContainer')
       let node = this.refs.node
-      let realm = this.get('realm')
-      this.store.set({currentRealm: realm})
+      this.store.setCurrentRealm(this.get('realm'))
       let scrollTop = this.store.get('scrollTop')
       if (scrollTop > 0) {
         this.observe('allVisibleItemsHaveHeight', allVisibleItemsHaveHeight => {

routes/_components/virtualList/virtualListStore.js

@@ -1,11 +1,11 @@
-import { Store } from 'svelte/store.js'
 import { mark, stop } from '../../_utils/marks'
+import { RealmStore } from '../../_utils/RealmStore'
 
 const VIEWPORT_RENDER_FACTOR = 4
 
-class VirtualListStore extends Store {
+class VirtualListStore extends RealmStore {
   constructor(state) {
-    super(state)
+    super(state, /* maxSize */ 10)
     this._batches = {}
   }
 
@@ -37,41 +37,18 @@ class VirtualListStore extends Store {
       stop('batchUpdate()')
     })
   }
-
-  setForRealm(obj) {
-    let realmName = this.get('currentRealm')
-    let realms = this.get('realms') || {}
-    realms[realmName] = Object.assign(realms[realmName] || {}, obj)
-    this.set({realms: realms})
-  }
 }
 
 const virtualListStore = new VirtualListStore({
-  realms: {},
-  currentRealm: null,
   itemHeights: {},
   footerHeight: 0
 })
 
-virtualListStore.compute('items', ['currentRealm', 'realms'], (currentRealm, realms) => {
-  return realms[currentRealm] && realms[currentRealm].items || []
-})
-
-virtualListStore.compute('showFooter', ['currentRealm', 'realms'], (currentRealm, realms) => {
-  return realms[currentRealm] && realms[currentRealm].showFooter
-})
-
-virtualListStore.compute('scrollTop', ['currentRealm', 'realms'], (currentRealm, realms) => {
-  return realms[currentRealm] && realms[currentRealm].scrollTop || 0
-})
-
-virtualListStore.compute('scrollHeight', ['currentRealm', 'realms'], (currentRealm, realms) => {
-  return realms[currentRealm] && realms[currentRealm].scrollHeight || 0
-})
-
-virtualListStore.compute('offsetHeight', ['currentRealm', 'realms'], (currentRealm, realms) => {
-  return realms[currentRealm] && realms[currentRealm].offsetHeight || 0
-})
+virtualListStore.computeForRealm('items', [])
+virtualListStore.computeForRealm('showFooter', false)
+virtualListStore.computeForRealm('scrollTop', 0)
+virtualListStore.computeForRealm('scrollHeight', 0)
+virtualListStore.computeForRealm('offsetHeight', 0)
 
 virtualListStore.compute('visibleItems',
     ['items', 'scrollTop', 'itemHeights', 'offsetHeight'],

routes/_utils/RealmStore.js

@@ -0,0 +1,32 @@
+// A store where you can divide data into "realms" that are backed with an LRU cache.
+// Each realm has self-contained data that you can set with setForRealm() and compute
+// with computeForRealm(). The maxSize determines how many realms to keep in the LRU cache.
+import { Store } from 'svelte/store.js'
+import QuickLRU from 'quick-lru'
+
+export class RealmStore extends Store {
+  constructor(init, maxSize) {
+    super(init)
+    this.set({realms: new QuickLRU({maxSize: maxSize})})
+  }
+
+  setCurrentRealm(realm) {
+    this.set({currentRealm: realm})
+  }
+
+  setForRealm(obj) {
+    let realmName = this.get('currentRealm')
+    let realms = this.get('realms')
+    realms.set(realmName, Object.assign(realms.get(realmName) || {}, obj))
+    this.set({realms: realms})
+  }
+
+  computeForRealm(key, defaultValue) {
+    this.compute(key,
+        ['realms', 'currentRealm'],
+        (realms, currentRealm) => {
+      let realmData = realms.get(currentRealm)
+      return (realmData && realmData[key]) || defaultValue
+    })
+  }
+}