feat(ivy): allow combined context discovery for components, directives and elements (#25754)
PR Close #25754
This commit is contained in:
Matias Niemelä
committed by
Igor Minar
Igor Minar
parent
d2dfd48be0
commit
62be8c2e2f
396
packages/core/src/render3/context_discovery.ts
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396
packages/core/src/render3/context_discovery.ts
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/**
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* @license
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* Copyright Google Inc. All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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import './ng_dev_mode';
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import {assertEqual} from './assert';
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import {LElementNode, TNode, TNodeFlags} from './interfaces/node';
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import {RElement} from './interfaces/renderer';
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import {CONTEXT, DIRECTIVES, HEADER_OFFSET, LViewData, TVIEW} from './interfaces/view';
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import {readElementValue} from './util';
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/**
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* This property will be monkey-patched on elements, components and directives
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*/
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export const MONKEY_PATCH_KEY_NAME = '__ngContext__';
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/**
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* The internal view context which is specific to a given DOM element, directive or
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* component instance. Each value in here (besides the LViewData and element node details)
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* can be present, null or undefined. If undefined then it implies the value has not been
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* looked up yet, otherwise, if null, then a lookup was executed and nothing was found.
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*
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* Each value will get filled when the respective value is examined within the getContext
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* function. The component, element and each directive instance will share the same instance
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* of the context.
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*/
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export interface LContext {
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/** The component\'s view data */
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lViewData: LViewData;
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/** The index instance of the LNode */
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lNodeIndex: number;
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/** The instance of the DOM node that is attached to the lNode */
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native: RElement;
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/** The instance of the Component node */
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component: {}|null|undefined;
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/** The list of indices for the active directives that exist on this element */
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directiveIndices: number[]|null|undefined;
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/** The list of active directives that exist on this element */
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directives: Array<{}>|null|undefined;
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}
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/** Returns the matching `LContext` data for a given DOM node, directive or component instance.
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*
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* This function will examine the provided DOM element, component, or directive instance\'s
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* monkey-patched property to derive the `LContext` data. Once called then the monkey-patched
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* value will be that of the newly created `LContext`.
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*
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* If the monkey-patched value is the `LViewData` instance then the context value for that
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* target will be created and the monkey-patch reference will be updated. Therefore when this
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* function is called it may mutate the provided element\'s, component\'s or any of the associated
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* directive\'s monkey-patch values.
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*
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* If the monkey-patch value is not detected then the code will walk up the DOM until an element
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* is found which contains a monkey-patch reference. When that occurs then the provided element
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* will be updated with a new context (which is then returned). If the monkey-patch value is not
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* detected for a component/directive instance then it will throw an error (all components and
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* directives should be automatically monkey-patched by ivy).
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*/
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export function getContext(target: any): LContext|null {
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let mpValue = readPatchedData(target);
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if (mpValue) {
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// only when it's an array is it considered an LViewData instance
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// ... otherwise it's an already constructed LContext instance
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if (Array.isArray(mpValue)) {
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const lViewData: LViewData = mpValue !;
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let lNodeIndex: number;
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let component: any = undefined;
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let directiveIndices: number[]|null|undefined = undefined;
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let directives: any[]|null|undefined = undefined;
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if (isComponentInstance(target)) {
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lNodeIndex = findViaComponent(lViewData, target);
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if (lNodeIndex == -1) {
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throw new Error('The provided component was not found in the application');
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}
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component = target;
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} else if (isDirectiveInstance(target)) {
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lNodeIndex = findViaDirective(lViewData, target);
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if (lNodeIndex == -1) {
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throw new Error('The provided directive was not found in the application');
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}
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directiveIndices = discoverDirectiveIndices(lViewData, lNodeIndex);
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directives = directiveIndices ? discoverDirectives(lViewData, directiveIndices) : null;
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} else {
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lNodeIndex = findViaNativeElement(lViewData, target as RElement);
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if (lNodeIndex == -1) {
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return null;
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}
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}
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// the goal is not to fill the entire context full of data because the lookups
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// are expensive. Instead, only the target data (the element, compontent or
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// directive details) are filled into the context. If called multiple times
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// with different target values then the missing target data will be filled in.
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const lNode = getLNodeFromViewData(lViewData, lNodeIndex) !;
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const existingCtx = readPatchedData(lNode.native);
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const context: LContext = (existingCtx && !Array.isArray(existingCtx)) ?
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existingCtx :
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createLContext(lViewData, lNodeIndex, lNode.native);
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// only when the component has been discovered then update the monkey-patch
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if (component && context.component === undefined) {
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context.component = component;
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attachPatchData(context.component, context);
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}
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// only when the directives have been discovered then update the monkey-patch
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if (directives && directiveIndices && context.directives === undefined) {
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context.directiveIndices = directiveIndices;
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context.directives = directives;
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for (let i = 0; i < directives.length; i++) {
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attachPatchData(directives[i], context);
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}
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}
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attachPatchData(context.native, context);
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mpValue = context;
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}
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} else {
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const rElement = target as RElement;
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ngDevMode && assertDomElement(rElement);
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// if the context is not found then we need to traverse upwards up the DOM
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// to find the nearest element that has already been monkey patched with data
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let parent = rElement as any;
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while (parent = parent.parentNode) {
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const parentContext = readPatchedData(parent);
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if (parentContext) {
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let lViewData: LViewData|null;
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if (Array.isArray(parentContext)) {
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lViewData = parentContext as LViewData;
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} else {
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lViewData = parentContext.lViewData;
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}
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// the edge of the app was also reached here through another means
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// (maybe because the DOM was changed manually).
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if (!lViewData) {
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return null;
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}
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const index = findViaNativeElement(lViewData, rElement);
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if (index >= 0) {
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const lNode = getLNodeFromViewData(lViewData, index) !;
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const context = createLContext(lViewData, index, lNode.native);
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attachPatchData(lNode.native, context);
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mpValue = context;
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break;
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}
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}
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}
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}
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return (mpValue as LContext) || null;
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}
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/**
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* Creates an empty instance of a `LContext` context
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*/
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function createLContext(lViewData: LViewData, lNodeIndex: number, native: RElement): LContext {
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return {
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lViewData,
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lNodeIndex,
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native,
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component: undefined,
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directiveIndices: undefined,
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directives: undefined,
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};
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}
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/**
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* A utility function for retrieving the matching lElementNode
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* from a given DOM element, component or directive.
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*/
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export function getLElementNode(target: any): LElementNode|null {
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const context = getContext(target);
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return context ? getLNodeFromViewData(context.lViewData, context.lNodeIndex) : null;
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}
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export function getLElementFromRootComponent(componentInstance: {}): LElementNode|null {
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// the host element for the root component is ALWAYS the first element
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// in the lViewData array (which is where HEADER_OFFSET points to)
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return getLElementFromComponent(componentInstance, HEADER_OFFSET);
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}
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/**
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* A simplified lookup function for finding the LElementNode from a component instance.
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*
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* This function exists for tree-shaking purposes to avoid having to pull in everything
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* that `getContext` has in the event that an Angular application doesn't need to have
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* any programmatic access to an element's context (only change detection uses this function).
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*/
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export function getLElementFromComponent(
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componentInstance: {}, expectedLNodeIndex?: number): LElementNode|null {
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let lViewData = readPatchedData(componentInstance);
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let lNode: LElementNode;
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if (Array.isArray(lViewData)) {
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expectedLNodeIndex = expectedLNodeIndex || findViaComponent(lViewData, componentInstance);
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lNode = readElementValue(lViewData[expectedLNodeIndex]);
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const context = createLContext(lViewData, expectedLNodeIndex, lNode.native);
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context.component = componentInstance;
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attachPatchData(componentInstance, context);
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attachPatchData(context.native, context);
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} else {
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const context = lViewData as any as LContext;
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lNode = readElementValue(context.lViewData[context.lNodeIndex]);
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}
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return lNode;
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}
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/**
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* Assigns the given data to the given target (which could be a component,
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* directive or DOM node instance) using monkey-patching.
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*/
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export function attachPatchData(target: any, data: LViewData | LContext) {
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target[MONKEY_PATCH_KEY_NAME] = data;
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}
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/**
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* Returns the monkey-patch value data present on the target (which could be
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* a component, directive or a DOM node).
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*/
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export function readPatchedData(target: any): LViewData|LContext|null {
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return target[MONKEY_PATCH_KEY_NAME];
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}
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export function isComponentInstance(instance: any): boolean {
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return instance && instance.constructor && instance.constructor.ngComponentDef;
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}
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export function isDirectiveInstance(instance: any): boolean {
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return instance && instance.constructor && instance.constructor.ngDirectiveDef;
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}
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/**
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* Locates the element within the given LViewData and returns the matching index
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*/
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function findViaNativeElement(lViewData: LViewData, native: RElement): number {
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let tNode = lViewData[TVIEW].firstChild;
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while (tNode) {
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const lNode = getLNodeFromViewData(lViewData, tNode.index) !;
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if (lNode.native === native) {
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return tNode.index;
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}
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tNode = traverseNextElement(tNode);
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}
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return -1;
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}
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/**
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* Locates the next tNode (child, sibling or parent).
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*/
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function traverseNextElement(tNode: TNode): TNode|null {
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if (tNode.child) {
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return tNode.child;
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} else if (tNode.next) {
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return tNode.next;
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} else if (tNode.parent) {
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return tNode.parent.next || null;
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}
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return null;
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}
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/**
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* Locates the component within the given LViewData and returns the matching index
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*/
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function findViaComponent(lViewData: LViewData, componentInstance: {}): number {
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const componentIndices = lViewData[TVIEW].components;
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if (componentIndices) {
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for (let i = 0; i < componentIndices.length; i++) {
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const elementComponentIndex = componentIndices[i];
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const lNodeData = readElementValue(lViewData[elementComponentIndex] !).data !;
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if (lNodeData[CONTEXT] === componentInstance) {
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return elementComponentIndex;
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}
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}
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} else {
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const rootNode = lViewData[HEADER_OFFSET];
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const rootComponent = rootNode.data[CONTEXT];
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if (rootComponent === componentInstance) {
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// we are dealing with the root element here therefore we know that the
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// element is the very first element after the HEADER data in the lView
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return HEADER_OFFSET;
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}
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}
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return -1;
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}
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/**
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* Locates the directive within the given LViewData and returns the matching index
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*/
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function findViaDirective(lViewData: LViewData, directiveInstance: {}): number {
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// if a directive is monkey patched then it will (by default)
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// have a reference to the LViewData of the current view. The
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// element bound to the directive being search lives somewhere
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// in the view data. By first checking to see if the instance
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// is actually present we can narrow down to which lElementNode
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// contains the instance of the directive and then return the index
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const directivesAcrossView = lViewData[DIRECTIVES];
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const directiveIndex =
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directivesAcrossView ? directivesAcrossView.indexOf(directiveInstance) : -1;
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if (directiveIndex >= 0) {
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let tNode = lViewData[TVIEW].firstChild;
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while (tNode) {
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const lNode = getLNodeFromViewData(lViewData, tNode.index) !;
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const directiveIndexStart = getDirectiveStartIndex(lNode);
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const directiveIndexEnd = getDirectiveEndIndex(lNode, directiveIndexStart);
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if (directiveIndex >= directiveIndexStart && directiveIndex < directiveIndexEnd) {
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return tNode.index;
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}
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tNode = traverseNextElement(tNode);
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}
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}
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return -1;
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}
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function assertDomElement(element: any) {
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assertEqual(element.nodeType, 1, 'The provided value must be an instance of an HTMLElement');
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}
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/**
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* Retruns the instance of the LElementNode at the given index in the LViewData.
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*
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* This function will also unwrap the inner value incase it's stuffed into an
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* array (which is what happens when [style] and [class] bindings are present
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* in the view instructions for the element being returned).
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*/
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function getLNodeFromViewData(lViewData: LViewData, lElementIndex: number): LElementNode|null {
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const value = lViewData[lElementIndex];
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return value ? readElementValue(value) : null;
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}
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/**
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* Returns a collection of directive index values that are used on the element
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* (which is referenced by the lNodeIndex)
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*/
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function discoverDirectiveIndices(lViewData: LViewData, lNodeIndex: number): number[]|null {
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const directivesAcrossView = lViewData[DIRECTIVES];
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const lNode = getLNodeFromViewData(lViewData, lNodeIndex);
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if (lNode && directivesAcrossView && directivesAcrossView.length) {
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// this check for tNode is to determine if the calue is a LEmementNode instance
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const directiveIndexStart = getDirectiveStartIndex(lNode);
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const directiveIndexEnd = getDirectiveEndIndex(lNode, directiveIndexStart);
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const directiveIndices: number[] = [];
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for (let i = directiveIndexStart; i < directiveIndexEnd; i++) {
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// special case since the instance of the component (if it exists)
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// is stored in the directives array.
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if (i > directiveIndexStart ||
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!isComponentInstance(directivesAcrossView[directiveIndexStart])) {
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directiveIndices.push(i);
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}
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}
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return directiveIndices.length ? directiveIndices : null;
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}
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return null;
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}
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function discoverDirectives(lViewData: LViewData, directiveIndices: number[]): number[]|null {
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const directives: any[] = [];
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const directiveInstances = lViewData[DIRECTIVES];
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if (directiveInstances) {
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for (let i = 0; i < directiveIndices.length; i++) {
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const directiveIndex = directiveIndices[i];
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const directive = directiveInstances[directiveIndex];
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directives.push(directive);
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}
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}
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return directives;
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}
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function getDirectiveStartIndex(lNode: LElementNode): number {
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// the tNode instances store a flag value which then has a
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// pointer which tells the starting index of where all the
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// active directives are in the master directive array
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return lNode.tNode.flags >> TNodeFlags.DirectiveStartingIndexShift;
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}
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function getDirectiveEndIndex(lNode: LElementNode, startIndex: number): number {
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// The end value is also apart of the same flag
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// (see `TNodeFlags` to see how the flag bit shifting
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// values are used).
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const count = lNode.tNode.flags & TNodeFlags.DirectiveCountMask;
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return count ? (startIndex + count) : -1;
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}
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