angular-docs-cn/modules/@angular/core/src/view/util.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {isDevMode} from '../application_ref';
import {WrappedValue, devModeEqual} from '../change_detection/change_detection';
import {SimpleChange} from '../change_detection/change_detection_util';
import {looseIdentical} from '../facade/lang';
import {Renderer} from '../render/api';

import {expressionChangedAfterItHasBeenCheckedError, isViewDebugError, viewDestroyedError, viewWrappedDebugError} from './errors';
import {ElementData, EntryAction, NodeData, NodeDef, NodeFlags, NodeType, ViewData, ViewDefinition, ViewDefinitionFactory, ViewFlags, ViewState, asElementData, asProviderData, asTextData} from './types';

export function setBindingDebugInfo(
    renderer: Renderer, renderNode: any, propName: string, value: any) {
  try {
    renderer.setBindingDebugInfo(
        renderNode, `ng-reflect-${camelCaseToDashCase(propName)}`, value ? value.toString() : null);
  } catch (e) {
    renderer.setBindingDebugInfo(
        renderNode, `ng-reflect-${camelCaseToDashCase(propName)}`,
        '[ERROR] Exception while trying to serialize the value');
  }
}

const CAMEL_CASE_REGEXP = /([A-Z])/g;

function camelCaseToDashCase(input: string): string {
  return input.replace(CAMEL_CASE_REGEXP, (...m: any[]) => '-' + m[1].toLowerCase());
}

export function checkBindingNoChanges(
    view: ViewData, def: NodeDef, bindingIdx: number, value: any) {
  const oldValue = view.oldValues[def.bindingIndex + bindingIdx];
  if (view.state === ViewState.FirstCheck || !devModeEqual(oldValue, value)) {
    throw expressionChangedAfterItHasBeenCheckedError(
        view.services.createDebugContext(view, def.index), oldValue, value,
        view.state === ViewState.FirstCheck);
  }
}

export function checkAndUpdateBinding(
    view: ViewData, def: NodeDef, bindingIdx: number, value: any): boolean {
  const oldValues = view.oldValues;
  if (view.state === ViewState.FirstCheck ||
      !looseIdentical(oldValues[def.bindingIndex + bindingIdx], value)) {
    oldValues[def.bindingIndex + bindingIdx] = value;
    if (def.flags & NodeFlags.HasComponent) {
      const compView = asProviderData(view, def.index).componentView;
      if (compView.state === ViewState.ChecksDisabled && compView.def.flags & ViewFlags.OnPush) {
        compView.state = ViewState.ChecksEnabled;
      }
    }
    return true;
  }
  return false;
}

export function dispatchEvent(
    view: ViewData, nodeIndex: number, eventName: string, event: any): boolean {
  setCurrentNode(view, nodeIndex);
  let currView = view;
  while (currView) {
    if (currView.state === ViewState.ChecksDisabled && currView.def.flags & ViewFlags.OnPush) {
      currView.state = ViewState.ChecksEnabled;
    }
    currView = currView.parent;
  }
  return view.def.handleEvent(view, nodeIndex, eventName, event);
}

export function unwrapValue(value: any): any {
  if (value instanceof WrappedValue) {
    value = value.wrapped;
  }
  return value;
}

export function declaredViewContainer(view: ViewData): ElementData {
  if (view.parent) {
    const parentView = view.parent;
    return asElementData(parentView, view.parentIndex);
  }
  return undefined;
}

export function renderNode(view: ViewData, def: NodeDef): any {
  switch (def.type) {
    case NodeType.Element:
      return asElementData(view, def.index).renderElement;
    case NodeType.Text:
      return asTextData(view, def.index).renderText;
  }
}

export function isComponentView(view: ViewData): boolean {
  return view.component === view.context && !!view.parent;
}

const VIEW_DEFINITION_CACHE = new WeakMap<any, ViewDefinition>();

export function resolveViewDefinition(factory: ViewDefinitionFactory): ViewDefinition {
  let value: ViewDefinition = VIEW_DEFINITION_CACHE.get(factory);
  if (!value) {
    value = factory();
    VIEW_DEFINITION_CACHE.set(factory, value);
  }
  return value;
}

export function sliceErrorStack(start: number, end: number): string {
  let err: any;
  try {
    throw new Error();
  } catch (e) {
    err = e;
  }
  const stack = err.stack || '';
  const lines = stack.split('\n');
  if (lines[0].startsWith('Error')) {
    // Chrome always adds the message to the stack as well...
    start++;
    end++;
  }
  return lines.slice(start, end).join('\n');
}

let _currentAction: EntryAction;
let _currentView: ViewData;
let _currentNodeIndex: number;

export function currentView() {
  return _currentView;
}

export function currentNodeIndex() {
  return _currentNodeIndex;
}

export function currentAction() {
  return _currentAction;
}

/**
 * Set the node that is currently worked on.
 * It needs to be called whenever we call user code,
 * or code of the framework that might throw as a valid use case.
 */
export function setCurrentNode(view: ViewData, nodeIndex: number) {
  if (view.state === ViewState.Destroyed) {
    throw viewDestroyedError(_currentAction);
  }
  _currentView = view;
  _currentNodeIndex = nodeIndex;
}

/**
 * Adds a try/catch handler around the given function to wrap all
 * errors that occur into new errors that contain the current debug info
 * set via setCurrentNode.
 */
export function entryAction<A, R>(action: EntryAction, fn: (arg: A) => R): (arg: A) => R {
  return <any>function(arg: any) {
    const oldAction = _currentAction;
    const oldView = _currentView;
    const oldNodeIndex = _currentNodeIndex;
    _currentAction = action;
    // Note: We can't call `isDevMode()` outside of this closure as
    // it might not have been initialized.
    const result = isDevMode() ? callWithTryCatch(fn, arg) : fn(arg);
    _currentAction = oldAction;
    _currentView = oldView;
    _currentNodeIndex = oldNodeIndex;
    return result;
  };
}

function callWithTryCatch(fn: (a: any) => any, arg: any): any {
  try {
    return fn(arg);
  } catch (e) {
    if (isViewDebugError(e) || !_currentView) {
      throw e;
    }
    const debugContext = _currentView.services.createDebugContext(_currentView, _currentNodeIndex);
    throw viewWrappedDebugError(e, debugContext);
  }
}

export function rootRenderNodes(view: ViewData): any[] {
  const renderNodes: any[] = [];
  visitRootRenderNodes(view, RenderNodeAction.Collect, undefined, undefined, renderNodes);
  return renderNodes;
}

export enum RenderNodeAction {
  Collect,
  AppendChild,
  InsertBefore,
  RemoveChild
}

export function visitRootRenderNodes(
    view: ViewData, action: RenderNodeAction, parentNode: any, nextSibling: any, target: any[]) {
  const len = view.def.nodes.length;
  for (let i = 0; i < len; i++) {
    const nodeDef = view.def.nodes[i];
    visitRenderNode(view, nodeDef, action, parentNode, nextSibling, target);
    // jump to next sibling
    i += nodeDef.childCount;
  }
}

export function visitProjectedRenderNodes(
    view: ViewData, ngContentIndex: number, action: RenderNodeAction, parentNode: any,
    nextSibling: any, target: any[]) {
  let compView = view;
  while (!isComponentView(compView)) {
    compView = compView.parent;
  }
  const hostView = compView.parent;
  const hostElDef = hostView.def.nodes[compView.parentIndex];
  const startIndex = hostElDef.index + 1;
  const endIndex = hostElDef.index + hostElDef.childCount;
  for (let i = startIndex; i <= endIndex; i++) {
    const nodeDef = hostView.def.nodes[i];
    if (nodeDef.ngContentIndex === ngContentIndex) {
      visitRenderNode(hostView, nodeDef, action, parentNode, nextSibling, target);
    }
    // jump to next sibling
    i += nodeDef.childCount;
  }
}

function visitRenderNode(
    view: ViewData, nodeDef: NodeDef, action: RenderNodeAction, parentNode: any, nextSibling: any,
    target: any[]) {
  if (nodeDef.type === NodeType.NgContent) {
    visitProjectedRenderNodes(
        view, nodeDef.ngContent.index, action, parentNode, nextSibling, target);
  } else {
    const rn = renderNode(view, nodeDef);
    switch (action) {
      case RenderNodeAction.AppendChild:
        parentNode.appendChild(rn);
        break;
      case RenderNodeAction.InsertBefore:
        parentNode.insertBefore(rn, nextSibling);
        break;
      case RenderNodeAction.RemoveChild:
        parentNode.removeChild(rn);
        break;
      case RenderNodeAction.Collect:
        target.push(rn);
        break;
    }
    if (nodeDef.flags & NodeFlags.HasEmbeddedViews) {
      const embeddedViews = asElementData(view, nodeDef.index).embeddedViews;
      if (embeddedViews) {
        for (let k = 0; k < embeddedViews.length; k++) {
          visitRootRenderNodes(embeddedViews[k], action, parentNode, nextSibling, target);
        }
      }
    }
  }
}