fix(runtime): implement prev/nextSibling getters

Author: rigor789

packages/runtime/__tests__/nodes.spec.ts

@@ -15,11 +15,9 @@ describe('NSVElement', () => {
 
   it('caches meta', () => {
     // mock getViewMeta
-    const getViewMeta = jest.fn(
-      (): NSVViewMeta => {
-        return { viewFlags: NSVViewFlags.SKIP_ADD_TO_DOM }
-      }
-    )
+    const getViewMeta = jest.fn((): NSVViewMeta => {
+      return { viewFlags: NSVViewFlags.SKIP_ADD_TO_DOM }
+    })
     const orig = require('../src/registry').getViewMeta
     require('../src/registry').getViewMeta = getViewMeta
 
@@ -57,6 +55,46 @@ describe('NSVElement', () => {
     expect(elem.lastChild).toBe(child2)
   })
 
+  it('returns prevSibling/nextSibling', () => {
+    const elem = new NSVElement('StackLayout')
+    const child1 = new NSVElement('Label')
+    const child2 = new NSVElement('Label')
+    const child3 = new NSVElement('Label')
+
+    expect(child1.prevSibling).toBe(null)
+    expect(child1.nextSibling).toBe(null)
+
+    expect(child2.prevSibling).toBe(null)
+    expect(child2.nextSibling).toBe(null)
+
+    expect(child3.prevSibling).toBe(null)
+    expect(child3.nextSibling).toBe(null)
+
+    elem.appendChild(child1)
+    elem.appendChild(child2)
+    elem.appendChild(child3)
+
+    expect(child1.prevSibling).toBe(null)
+    expect(child1.nextSibling).toBe(child2)
+
+    expect(child2.prevSibling).toBe(child1)
+    expect(child2.nextSibling).toBe(child3)
+
+    expect(child3.prevSibling).toBe(child2)
+    expect(child3.nextSibling).toBe(null)
+
+    elem.removeChild(child2)
+
+    expect(child1.prevSibling).toBe(null)
+    expect(child1.nextSibling).toBe(child3)
+
+    expect(child2.prevSibling).toBe(null)
+    expect(child2.nextSibling).toBe(null)
+
+    expect(child3.prevSibling).toBe(child1)
+    expect(child3.nextSibling).toBe(null)
+  })
+
   it('insertBefore falls back to appendChild if anchor not found', () => {
     const elem = new NSVElement('StackLayout')
     const child = new NSVElement('Label')

packages/runtime/src/nodes.ts

@@ -98,8 +98,37 @@ export abstract class NSVNode implements INSVNode {
   parentNode: INSVElement | null = null
   childNodes: INSVNode[] = []
 
-  nextSibling: INSVNode | null = null
-  prevSibling: INSVNode | null = null
+  get nextSibling(): INSVNode | null {
+    if (!this.parentNode) {
+      return null
+    }
+
+    const selfIndex = this.parentNode.childNodes.findIndex(
+      (n) => n.nodeId === this.nodeId
+    )
+
+    if (selfIndex > -1 && selfIndex < this.parentNode.childNodes.length - 1) {
+      return this.parentNode.childNodes[selfIndex + 1]
+    }
+
+    return null
+  }
+
+  get prevSibling(): INSVNode | null {
+    if (!this.parentNode) {
+      return null
+    }
+
+    const selfIndex = this.parentNode.childNodes.findIndex(
+      (n) => n.nodeId === this.nodeId
+    )
+
+    if (selfIndex > 0) {
+      return this.parentNode.childNodes[selfIndex - 1]
+    }
+
+    return null
+  }
 
   get firstChild() {
     return this.childNodes.length ? this.childNodes[0] : null