refactor(core): change getPreviousOrParentTNode to return `TNode|nu…

…ll` (#38707) This change makes `getPreviousOrParentTNode` return `TNode|null` (rather than just `TNode`) which is more reflective of the reality. The `getPreviousOrParentTNode` can be `null` upon entering the `LView`. PR Close #38707
angular · alxhub · Sep 29, 2020 · Sep 17, 2020 · Sep 4, 2020 · Sep 4, 2020
commit 0fa208f624adf0f3c3cb7bd5e05ac52645323717
diff --git a/packages/core/src/render3/component.ts b/packages/core/src/render3/component.ts
@@ -229,7 +229,7 @@ export function createRootComponent<T>(
     componentDef.contentQueries(RenderFlags.Create, component, rootLView.length - 1);
   }
 
-  const rootTNode = getPreviousOrParentTNode();
+  const rootTNode = getPreviousOrParentTNode()!;
   if (tView.firstCreatePass &&
       (componentDef.hostBindings !== null || componentDef.hostAttrs !== null)) {
     const elementIndex = rootTNode.index - HEADER_OFFSET;

diff --git a/packages/core/src/render3/di_setup.ts b/packages/core/src/render3/di_setup.ts
@@ -76,7 +76,7 @@ function resolveProvider(
     let token: any = isTypeProvider(provider) ? provider : resolveForwardRef(provider.provide);
     let providerFactory: () => any = providerToFactory(provider);
 
-    const tNode = getPreviousOrParentTNode();
+    const tNode = getPreviousOrParentTNode()!;
     const beginIndex = tNode.providerIndexes & TNodeProviderIndexes.ProvidersStartIndexMask;
     const endIndex = tNode.directiveStart;
     const cptViewProvidersCount =

diff --git a/packages/core/src/render3/i18n/i18n_parse.ts b/packages/core/src/render3/i18n/i18n_parse.ts
@@ -70,7 +70,7 @@ export function i18nStartFirstPass(
     lView: LView, tView: TView, index: number, message: string, subTemplateIndex?: number) {
   const startIndex = tView.blueprint.length - HEADER_OFFSET;
   i18nVarsCount = 0;
-  const previousOrParentTNode = getPreviousOrParentTNode();
+  const previousOrParentTNode = getPreviousOrParentTNode()!;
   const parentTNode =
       getIsParent() ? previousOrParentTNode : previousOrParentTNode && previousOrParentTNode.parent;
   let parentIndex =
@@ -212,7 +212,7 @@ export function i18nStartFirstPass(
  */
 export function i18nAttributesFirstPass(
     lView: LView, tView: TView, index: number, values: string[]) {
-  const previousElement = getPreviousOrParentTNode();
+  const previousElement = getPreviousOrParentTNode()!;
   const previousElementIndex = previousElement.index - HEADER_OFFSET;
   const updateOpCodes: I18nUpdateOpCodes = [];
   if (ngDevMode) {

diff --git a/packages/core/src/render3/instructions/di.ts b/packages/core/src/render3/instructions/di.ts
@@ -59,7 +59,7 @@ export function ɵɵdirectiveInject<T>(
  * @codeGenApi
  */
 export function ɵɵinjectAttribute(attrNameToInject: string): string|null {
-  return injectAttributeImpl(getPreviousOrParentTNode(), attrNameToInject);
+  return injectAttributeImpl(getPreviousOrParentTNode()!, attrNameToInject);
 }
 
 /**

diff --git a/packages/core/src/render3/instructions/element.ts b/packages/core/src/render3/instructions/element.ts
@@ -128,7 +128,7 @@ export function ɵɵelementStart(
  * @codeGenApi
  */
 export function ɵɵelementEnd(): void {
-  let previousOrParentTNode = getPreviousOrParentTNode();
+  let previousOrParentTNode = getPreviousOrParentTNode()!;
   ngDevMode && assertDefined(previousOrParentTNode, 'No parent node to close.');
   if (getIsParent()) {
     setIsNotParent();

diff --git a/packages/core/src/render3/instructions/element_container.ts b/packages/core/src/render3/instructions/element_container.ts
@@ -98,7 +98,7 @@ export function ɵɵelementContainerStart(
  * @codeGenApi
  */
 export function ɵɵelementContainerEnd(): void {
-  let previousOrParentTNode = getPreviousOrParentTNode();
+  let previousOrParentTNode = getPreviousOrParentTNode()!;
   const tView = getTView();
   if (getIsParent()) {
     setIsNotParent();

diff --git a/packages/core/src/render3/instructions/listener.ts b/packages/core/src/render3/instructions/listener.ts
@@ -41,7 +41,7 @@ export function ɵɵlistener(
     eventTargetResolver?: GlobalTargetResolver): typeof ɵɵlistener {
   const lView = getLView();
   const tView = getTView();
-  const tNode = getPreviousOrParentTNode();
+  const tNode = getPreviousOrParentTNode()!;
   listenerInternal(
       tView, lView, lView[RENDERER], tNode, eventName, listenerFn, useCapture, eventTargetResolver);
   return ɵɵlistener;
@@ -71,7 +71,7 @@ export function ɵɵlistener(
 export function ɵɵsyntheticHostListener(
     eventName: string, listenerFn: (e?: any) => any, useCapture = false,
     eventTargetResolver?: GlobalTargetResolver): typeof ɵɵsyntheticHostListener {
-  const tNode = getPreviousOrParentTNode();
+  const tNode = getPreviousOrParentTNode()!;
   const lView = getLView();
   const tView = getTView();
   const currentDef = getCurrentDirectiveDef(tView.data);

diff --git a/packages/core/src/render3/instructions/shared.ts b/packages/core/src/render3/instructions/shared.ts
@@ -1125,7 +1125,7 @@ function logUnknownPropertyError(propName: string, tNode: TNode): void {
  * Instantiate a root component.
  */
 export function instantiateRootComponent<T>(tView: TView, lView: LView, def: ComponentDef<T>): T {
-  const rootTNode = getPreviousOrParentTNode();
+  const rootTNode = getPreviousOrParentTNode()!;
   if (tView.firstCreatePass) {
     if (def.providersResolver) def.providersResolver(def);
     generateExpandoInstructionBlock(tView, rootTNode, 1);

diff --git a/packages/core/src/render3/query.ts b/packages/core/src/render3/query.ts
@@ -504,7 +504,7 @@ export function ɵɵcontentQuery<T>(
     directiveIndex: number, predicate: Type<any>|InjectionToken<unknown>|string[], descend: boolean,
     read?: any): void {
   contentQueryInternal(
-      getTView(), getLView(), predicate, descend, read, false, getPreviousOrParentTNode(),
+      getTView(), getLView(), predicate, descend, read, false, getPreviousOrParentTNode()!,
       directiveIndex);
 }
 
@@ -524,7 +524,7 @@ export function ɵɵstaticContentQuery<T>(
     directiveIndex: number, predicate: Type<any>|InjectionToken<unknown>|string[], descend: boolean,
     read?: any): void {
   contentQueryInternal(
-      getTView(), getLView(), predicate, descend, read, true, getPreviousOrParentTNode(),
+      getTView(), getLView(), predicate, descend, read, true, getPreviousOrParentTNode()!,
       directiveIndex);
 }
 

diff --git a/packages/core/src/render3/state.ts b/packages/core/src/render3/state.ts
@@ -54,8 +54,7 @@ interface LFrame {
    *
    * This is used in conjunction with `isParent`.
    */
-  // FIXME(misko): should be `TNode|null` (add comment explaining it.)
-  previousOrParentTNode: TNode;
+  previousOrParentTNode: TNode|null;
 
   /**
    * If `isParent` is:
@@ -263,7 +262,7 @@ export function ɵɵrestoreView(viewToRestore: OpaqueViewState) {
   instructionState.lFrame.contextLView = viewToRestore as any as LView;
 }
 
-export function getPreviousOrParentTNode(): TNode {
+export function getPreviousOrParentTNode(): TNode|null {
   return instructionState.lFrame.previousOrParentTNode;
 }
 
@@ -441,20 +440,20 @@ function allocLFrame() {
 
 function createLFrame(parent: LFrame|null): LFrame {
   const lFrame: LFrame = {
-    previousOrParentTNode: null!,  //
-    isParent: true,                //
-    lView: null!,                  //
-    tView: null!,                  //
-    selectedIndex: 0,              //
-    contextLView: null!,           //
-    elementDepthCount: 0,          //
-    currentNamespace: null,        //
-    currentDirectiveIndex: -1,     //
-    bindingRootIndex: -1,          //
-    bindingIndex: -1,              //
-    currentQueryIndex: 0,          //
-    parent: parent!,               //
-    child: null,                   //
+    previousOrParentTNode: null,  //
+    isParent: true,               //
+    lView: null!,                 //
+    tView: null!,                 //
+    selectedIndex: 0,             //
+    contextLView: null!,          //
+    elementDepthCount: 0,         //
+    currentNamespace: null,       //
+    currentDirectiveIndex: -1,    //
+    bindingRootIndex: -1,         //
+    bindingIndex: -1,             //
+    currentQueryIndex: 0,         //
+    parent: parent!,              //
+    child: null,                  //
   };
   parent !== null && (parent.child = lFrame);  // link the new LFrame for reuse.
   return lFrame;

diff --git a/packages/core/src/render3/v DE16 iew_engine_compatibility.ts b/packages/core/src/render3/v DE16 iew_engine_compatibility.ts
@@ -43,7 +43,7 @@ import {ViewRef} from './view_ref';
  */
 export function injectElementRef(ElementRefToken: typeof ViewEngine_ElementRef):
     ViewEngine_ElementRef {
-  return createElementRef(ElementRefToken, getPreviousOrParentTNode(), getLView());
+  return createElementRef(ElementRefToken, getPreviousOrParentTNode()!, getLView());
 }
 
 let R3ElementRef: {new (native: RElement|RComment): ViewEngine_ElementRef};
@@ -79,7 +79,7 @@ export function injectTemplateRef<T>(
     TemplateRefToken: typeof ViewEngine_TemplateRef,
     ElementRefToken: typeof ViewEngine_ElementRef): ViewEngine_TemplateRef<T>|null {
   return createTemplateRef<T>(
-      TemplateRefToken, ElementRefToken, getPreviousOrParentTNode(), getLView());
+      TemplateRefToken, ElementRefToken, getPreviousOrParentTNode()!, getLView());
 }
 
 /**
@@ -407,7 +407,7 @@ export function createContainerRef(
 
 /** Returns a ChangeDetectorRef (a.k.a. a ViewRef) */
 export function injectChangeDetectorRef(isPipe = false): ViewEngine_ChangeDetectorRef {
-  return createViewRef(getPreviousOrParentTNode(), getLView(), isPipe);
+  return createViewRef(getPreviousOrParentTNode()!, getLView(), isPipe);
 }
 
 /**
@@ -453,7 +453,7 @@ export function injectRenderer2(): Renderer2 {
   // We need the Renderer to be based on the component that it's being injected into, however since
   // DI happens before we've entered its view, `getLView` will return the parent view instead.
   const lView = getLView();
-  const tNode = getPreviousOrParentTNode();
+  const tNode = getPreviousOrParentTNode()!;
   const nodeAtIndex = getComponentLViewByIndex(tNode.index, lView);
   return getOrCreateRenderer2(isLView(nodeAtIndex) ? nodeAtIndex : lView);
 }