angular-docs-cn/packages/core/src/render3/node_manipulation.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 {ViewEncapsulation} from '../metadata/view';
import {assertDefined, assertDomNode} from '../util/assert';

import {assertLContainer, assertLView} from './assert';
import {attachPatchData} from './context_discovery';
import {CONTAINER_HEADER_OFFSET, LContainer, NATIVE, unusedValueExportToPlacateAjd as unused1} from './interfaces/container';
import {ComponentDef} from './interfaces/definition';
import {NodeInjectorFactory} from './interfaces/injector';
import {TElementContainerNode, TElementNode, TNode, TNodeFlags, TNodeType, TProjectionNode, TViewNode, unusedValueExportToPlacateAjd as unused2} from './interfaces/node';
import {unusedValueExportToPlacateAjd as unused3} from './interfaces/projection';
import {ProceduralRenderer3, RElement, RNode, RText, Renderer3, isProceduralRenderer, unusedValueExportToPlacateAjd as unused4} from './interfaces/renderer';
import {StylingContext} from './interfaces/styling';
import {CHILD_HEAD, CLEANUP, FLAGS, HOST, HookData, LView, LViewFlags, NEXT, PARENT, QUERIES, RENDERER, TVIEW, T_HOST, unusedValueExportToPlacateAjd as unused5} from './interfaces/view';
import {assertNodeOfPossibleTypes, assertNodeType} from './node_assert';
import {renderStringify} from './util/misc_utils';
import {findComponentView, getLViewParent} from './util/view_traversal_utils';
import {getNativeByTNode, isLContainer, isLView, isRootView, unwrapRNode, viewAttachedToContainer} from './util/view_utils';


const unusedValueToPlacateAjd = unused1 + unused2 + unused3 + unused4 + unused5;

export function getLContainer(tNode: TViewNode, embeddedView: LView): LContainer|null {
  ngDevMode && assertLView(embeddedView);
  const container = embeddedView[PARENT] as LContainer;
  if (tNode.index === -1) {
    // This is a dynamically created view inside a dynamic container.
    // The parent isn't an LContainer if the embedded view hasn't been attached yet.
    return isLContainer(container) ? container : null;
  } else {
    ngDevMode && assertLContainer(container);
    // This is a inline view node (e.g. embeddedViewStart)
    return container;
  }
}


/**
 * Retrieves render parent for a given view.
 * Might be null if a view is not yet attached to any container.
 */
function getContainerRenderParent(tViewNode: TViewNode, view: LView): RElement|null {
  const container = getLContainer(tViewNode, view);
  return container ? nativeParentNode(view[RENDERER], container[NATIVE]) : null;
}

const enum WalkTNodeTreeAction {
  /** node insert in the native environment */
  Insert = 0,

  /** node detach from the native environment */
  Detach = 1,

  /** node destruction using the renderer's API */
  Destroy = 2,
}



/**
 * NOTE: for performance reasons, the possible actions are inlined within the function instead of
 * being passed as an argument.
 */
function executeActionOnElementOrContainer(
    action: WalkTNodeTreeAction, renderer: Renderer3, parent: RElement | null,
    lNodeToHandle: RNode | LContainer | LView | StylingContext, beforeNode?: RNode | null) {
  ngDevMode && assertDefined(lNodeToHandle, '\'lNodeToHandle\' is undefined');
  let lContainer: LContainer|undefined;
  let isComponent = false;
  // We are expecting an RNode, but in the case of a component or LContainer the `RNode` is wrapped
  // in an array which needs to be unwrapped. We need to know if it is a component and if
  // it has LContainer so that we can process all of those cases appropriately.
  if (isLContainer(lNodeToHandle)) {
    lContainer = lNodeToHandle;
  } else if (isLView(lNodeToHandle)) {
    isComponent = true;
    ngDevMode && assertDefined(lNodeToHandle[HOST], 'HOST must be defined for a component LView');
    lNodeToHandle = lNodeToHandle[HOST] !;
  }
  const rNode: RNode = unwrapRNode(lNodeToHandle);
  ngDevMode && assertDomNode(rNode);

  if (action === WalkTNodeTreeAction.Insert) {
    nativeInsertBefore(renderer, parent !, rNode, beforeNode || null);
  } else if (action === WalkTNodeTreeAction.Detach) {
    nativeRemoveNode(renderer, rNode, isComponent);
  } else if (action === WalkTNodeTreeAction.Destroy) {
    ngDevMode && ngDevMode.rendererDestroyNode++;
    (renderer as ProceduralRenderer3).destroyNode !(rNode);
  }
  if (lContainer != null) {
    executeActionOnContainer(renderer, action, lContainer, parent, beforeNode);
  }
}

export function createTextNode(value: any, renderer: Renderer3): RText {
  return isProceduralRenderer(renderer) ? renderer.createText(renderStringify(value)) :
                                          renderer.createTextNode(renderStringify(value));
}

/**
 * Adds or removes all DOM elements associated with a view.
 *
 * Because some root nodes of the view may be containers, we sometimes need
 * to propagate deeply into the nested containers to remove all elements in the
 * views beneath it.
 *
 * @param lView The view from which elements should be added or removed
 * @param insertMode Whether or not elements should be added (if false, removing)
 * @param beforeNode The node before which elements should be added, if insert mode
 */
export function addRemoveViewFromContainer(
    lView: LView, insertMode: true, beforeNode: RNode | null): void;
export function addRemoveViewFromContainer(lView: LView, insertMode: false): void;
export function addRemoveViewFromContainer(
    lView: LView, insertMode: boolean, beforeNode?: RNode | null): void {
  const renderParent = getContainerRenderParent(lView[TVIEW].node as TViewNode, lView);
  ngDevMode && assertNodeType(lView[TVIEW].node as TNode, TNodeType.View);
  if (renderParent) {
    const renderer = lView[RENDERER];
    const action = insertMode ? WalkTNodeTreeAction.Insert : WalkTNodeTreeAction.Detach;
    executeActionOnView(renderer, action, lView, renderParent, beforeNode);
  }
}

/**
 * Detach a `LView` from the DOM by detaching its nodes.
 *
 * @param lView the `LView` to be detached.
 */
export function renderDetachView(lView: LView) {
  executeActionOnView(lView[RENDERER], WalkTNodeTreeAction.Detach, lView, null, null);
}

/**
 * Traverses down and up the tree of views and containers to remove listeners and
 * call onDestroy callbacks.
 *
 * Notes:
 *  - Because it's used for onDestroy calls, it needs to be bottom-up.
 *  - Must process containers instead of their views to avoid splicing
 *  when views are destroyed and re-added.
 *  - Using a while loop because it's faster than recursion
 *  - Destroy only called on movement to sibling or movement to parent (laterally or up)
 *
 *  @param rootView The view to destroy
 */
export function destroyViewTree(rootView: LView): void {
  // If the view has no children, we can clean it up and return early.
  let lViewOrLContainer = rootView[CHILD_HEAD];
  if (!lViewOrLContainer) {
    return cleanUpView(rootView);
  }

  while (lViewOrLContainer) {
    let next: LView|LContainer|null = null;

    if (isLView(lViewOrLContainer)) {
      // If LView, traverse down to child.
      next = lViewOrLContainer[CHILD_HEAD];
    } else {
      ngDevMode && assertLContainer(lViewOrLContainer);
      // If container, traverse down to its first LView.
      const firstView: LView|undefined = lViewOrLContainer[CONTAINER_HEADER_OFFSET];
      if (firstView) next = firstView;
    }

    if (!next) {
      // Only clean up view when moving to the side or up, as destroy hooks
      // should be called in order from the bottom up.
      while (lViewOrLContainer && !lViewOrLContainer ![NEXT] && lViewOrLContainer !== rootView) {
        cleanUpView(lViewOrLContainer);
        lViewOrLContainer = getParentState(lViewOrLContainer, rootView);
      }
      cleanUpView(lViewOrLContainer || rootView);
      next = lViewOrLContainer && lViewOrLContainer ![NEXT];
    }
    lViewOrLContainer = next;
  }
}

/**
 * Inserts a view into a container.
 *
 * This adds the view to the container's array of active views in the correct
 * position. It also adds the view's elements to the DOM if the container isn't a
 * root node of another view (in that case, the view's elements will be added when
 * the container's parent view is added later).
 *
 * @param lView The view to insert
 * @param lContainer The container into which the view should be inserted
 * @param index Which index in the container to insert the child view into
 */
export function insertView(lView: LView, lContainer: LContainer, index: number) {
  ngDevMode && assertLView(lView);
  ngDevMode && assertLContainer(lContainer);
  const indexInContainer = CONTAINER_HEADER_OFFSET + index;
  const containerLength = lContainer.length;

  if (index > 0) {
    // This is a new view, we need to add it to the children.
    lContainer[indexInContainer - 1][NEXT] = lView;
  }
  if (index < containerLength - CONTAINER_HEADER_OFFSET) {
    lView[NEXT] = lContainer[indexInContainer];
    lContainer.splice(CONTAINER_HEADER_OFFSET + index, 0, lView);
  } else {
    lContainer.push(lView);
    lView[NEXT] = null;
  }

  lView[PARENT] = lContainer;

  // Notify query that a new view has been added
  if (lView[QUERIES]) {
    lView[QUERIES] !.insertView(index);
  }

  // Sets the attached flag
  lView[FLAGS] |= LViewFlags.Attached;
}

/**
 * Detaches a view from a container.
 *
 * This method splices the view from the container's array of active views. It also
 * removes the view's elements from the DOM.
 *
 * @param lContainer The container from which to detach a view
 * @param removeIndex The index of the view to detach
 * @returns Detached LView instance.
 */
export function detachView(lContainer: LContainer, removeIndex: number): LView|undefined {
  if (lContainer.length <= CONTAINER_HEADER_OFFSET) return;

  const indexInContainer = CONTAINER_HEADER_OFFSET + removeIndex;
  const viewToDetach = lContainer[indexInContainer];
  if (viewToDetach) {
    if (removeIndex > 0) {
      lContainer[indexInContainer - 1][NEXT] = viewToDetach[NEXT] as LView;
    }
    lContainer.splice(CONTAINER_HEADER_OFFSET + removeIndex, 1);
    addRemoveViewFromContainer(viewToDetach, false);

    if ((viewToDetach[FLAGS] & LViewFlags.Attached) &&
        !(viewToDetach[FLAGS] & LViewFlags.Destroyed) && viewToDetach[QUERIES]) {
      viewToDetach[QUERIES] !.removeView();
    }
    viewToDetach[PARENT] = null;
    viewToDetach[NEXT] = null;
    // Unsets the attached flag
    viewToDetach[FLAGS] &= ~LViewFlags.Attached;
  }
  return viewToDetach;
}

/**
 * Removes a view from a container, i.e. detaches it and then destroys the underlying LView.
 *
 * @param lContainer The container from which to remove a view
 * @param removeIndex The index of the view to remove
 */
export function removeView(lContainer: LContainer, removeIndex: number) {
  const detachedView = detachView(lContainer, removeIndex);
  detachedView && destroyLView(detachedView);
}

/**
 * A standalone function which destroys an LView,
 * conducting cleanup (e.g. removing listeners, calling onDestroys).
 *
 * @param lView The view to be destroyed.
 */
export function destroyLView(lView: LView) {
  if (!(lView[FLAGS] & LViewFlags.Destroyed)) {
    const renderer = lView[RENDERER];
    if (isProceduralRenderer(renderer) && renderer.destroyNode) {
      executeActionOnView(renderer, WalkTNodeTreeAction.Destroy, lView, null, null);
    }

    destroyViewTree(lView);
  }
}

/**
 * Determines which LViewOrLContainer to jump to when traversing back up the
 * tree in destroyViewTree.
 *
 * Normally, the view's parent LView should be checked, but in the case of
 * embedded views, the container (which is the view node's parent, but not the
 * LView's parent) needs to be checked for a possible next property.
 *
 * @param lViewOrLContainer The LViewOrLContainer for which we need a parent state
 * @param rootView The rootView, so we don't propagate too far up the view tree
 * @returns The correct parent LViewOrLContainer
 */
export function getParentState(lViewOrLContainer: LView | LContainer, rootView: LView): LView|
    LContainer|null {
  let tNode;
  if (isLView(lViewOrLContainer) && (tNode = lViewOrLContainer[T_HOST]) &&
      tNode.type === TNodeType.View) {
    // if it's an embedded view, the state needs to go up to the container, in case the
    // container has a next
    return getLContainer(tNode as TViewNode, lViewOrLContainer);
  } else {
    // otherwise, use parent view for containers or component views
    return lViewOrLContainer[PARENT] === rootView ? null : lViewOrLContainer[PARENT];
  }
}

/**
 * Calls onDestroys hooks for all directives and pipes in a given view and then removes all
 * listeners. Listeners are removed as the last step so events delivered in the onDestroys hooks
 * can be propagated to @Output listeners.
 *
 * @param view The LView to clean up
 */
function cleanUpView(view: LView | LContainer): void {
  if (isLView(view) && !(view[FLAGS] & LViewFlags.Destroyed)) {
    // Usually the Attached flag is removed when the view is detached from its parent, however
    // if it's a root view, the flag won't be unset hence why we're also removing on destroy.
    view[FLAGS] &= ~LViewFlags.Attached;

    // Mark the LView as destroyed *before* executing the onDestroy hooks. An onDestroy hook
    // runs arbitrary user code, which could include its own `viewRef.destroy()` (or similar). If
    // We don't flag the view as destroyed before the hooks, this could lead to an infinite loop.
    // This also aligns with the ViewEngine behavior. It also means that the onDestroy hook is
    // really more of an "afterDestroy" hook if you think about it.
    view[FLAGS] |= LViewFlags.Destroyed;

    executeOnDestroys(view);
    removeListeners(view);
    const hostTNode = view[T_HOST];
    // For component views only, the local renderer is destroyed as clean up time.
    if (hostTNode && hostTNode.type === TNodeType.Element && isProceduralRenderer(view[RENDERER])) {
      ngDevMode && ngDevMode.rendererDestroy++;
      (view[RENDERER] as ProceduralRenderer3).destroy();
    }
    // For embedded views still attached to a container: remove query result from this view.
    if (viewAttachedToContainer(view) && view[QUERIES]) {
      view[QUERIES] !.removeView();
    }
  }
}

/** Removes listeners and unsubscribes from output subscriptions */
function removeListeners(lView: LView): void {
  const tCleanup = lView[TVIEW].cleanup;
  if (tCleanup !== null) {
    const lCleanup = lView[CLEANUP] !;
    for (let i = 0; i < tCleanup.length - 1; i += 2) {
      if (typeof tCleanup[i] === 'string') {
        // This is a native DOM listener
        const idxOrTargetGetter = tCleanup[i + 1];
        const target = typeof idxOrTargetGetter === 'function' ?
            idxOrTargetGetter(lView) :
            unwrapRNode(lView[idxOrTargetGetter]);
        const listener = lCleanup[tCleanup[i + 2]];
        const useCaptureOrSubIdx = tCleanup[i + 3];
        if (typeof useCaptureOrSubIdx === 'boolean') {
          // native DOM listener registered with Renderer3
          target.removeEventListener(tCleanup[i], listener, useCaptureOrSubIdx);
        } else {
          if (useCaptureOrSubIdx >= 0) {
            // unregister
            lCleanup[useCaptureOrSubIdx]();
          } else {
            // Subscription
            lCleanup[-useCaptureOrSubIdx].unsubscribe();
          }
        }
        i += 2;
      } else {
        // This is a cleanup function that is grouped with the index of its context
        const context = lCleanup[tCleanup[i + 1]];
        tCleanup[i].call(context);
      }
    }
    lView[CLEANUP] = null;
  }
}

/** Calls onDestroy hooks for this view */
function executeOnDestroys(view: LView): void {
  const tView = view[TVIEW];
  let destroyHooks: HookData|null;

  if (tView != null && (destroyHooks = tView.destroyHooks) != null) {
    for (let i = 0; i < destroyHooks.length; i += 2) {
      const context = view[destroyHooks[i] as number];

      // Only call the destroy hook if the context has been requested.
      if (!(context instanceof NodeInjectorFactory)) {
        (destroyHooks[i + 1] as() => void).call(context);
      }
    }
  }
}

/**
 * Returns a native element if a node can be inserted into the given parent.
 *
 * There are two reasons why we may not be able to insert a element immediately.
 * - Projection: When creating a child content element of a component, we have to skip the
 *   insertion because the content of a component will be projected.
 *   `<component><content>delayed due to projection</content></component>`
 * - Parent container is disconnected: This can happen when we are inserting a view into
 *   parent container, which itself is disconnected. For example the parent container is part
 *   of a View which has not be inserted or is made for projection but has not been inserted
 *   into destination.
 */
function getRenderParent(tNode: TNode, currentView: LView): RElement|null {
  // Nodes of the top-most view can be inserted eagerly.
  if (isRootView(currentView)) {
    return nativeParentNode(currentView[RENDERER], getNativeByTNode(tNode, currentView));
  }

  // Skip over element and ICU containers as those are represented by a comment node and
  // can't be used as a render parent.
  const parent = getHighestElementOrICUContainer(tNode);
  const renderParent = parent.parent;

  // If the parent is null, then we are inserting across views: either into an embedded view or a
  // component view.
  if (renderParent == null) {
    const hostTNode = currentView[T_HOST] !;
    if (hostTNode.type === TNodeType.View) {
      // We are inserting a root element of an embedded view We might delay insertion of children
      // for a given view if it is disconnected. This might happen for 2 main reasons:
      // - view is not inserted into any container(view was created but not inserted yet)
      // - view is inserted into a container but the container itself is not inserted into the DOM
      // (container might be part of projection or child of a view that is not inserted yet).
      // In other words we can insert children of a given view if this view was inserted into a
      // container and the container itself has its render parent determined.
      return getContainerRenderParent(hostTNode as TViewNode, currentView);
    } else {
      // We are inserting a root element of the component view into the component host element and
      // it should always be eager.
      return getHostNative(currentView);
    }
  } else {
    const isIcuCase = parent && parent.type === TNodeType.IcuContainer;
    // If the parent of this node is an ICU container, then it is represented by comment node and we
    // need to use it as an anchor. If it is projected then its direct parent node is the renderer.
    if (isIcuCase && parent.flags & TNodeFlags.isProjected) {
      return getNativeByTNode(parent, currentView).parentNode as RElement;
    }

    ngDevMode && assertNodeType(renderParent, TNodeType.Element);
    if (renderParent.flags & TNodeFlags.isComponent && !isIcuCase) {
      const tData = currentView[TVIEW].data;
      const tNode = tData[renderParent.index] as TNode;
      const encapsulation = (tData[tNode.directiveStart] as ComponentDef<any>).encapsulation;

      // We've got a parent which is an element in the current view. We just need to verify if the
      // parent element is not a component. Component's content nodes are not inserted immediately
      // because they will be projected, and so doing insert at this point would be wasteful.
      // Since the projection would then move it to its final destination. Note that we can't
      // make this assumption when using the Shadow DOM, because the native projection placeholders
      // (<content> or <slot>) have to be in place as elements are being inserted.
      if (encapsulation !== ViewEncapsulation.ShadowDom &&
          encapsulation !== ViewEncapsulation.Native) {
        return null;
      }
    }

    return getNativeByTNode(renderParent, currentView) as RElement;
  }
}

/**
 * Gets the native host element for a given view. Will return null if the current view does not have
 * a host element.
 */
function getHostNative(currentView: LView): RElement|null {
  ngDevMode && assertLView(currentView);
  const hostTNode = currentView[T_HOST];
  return hostTNode && hostTNode.type === TNodeType.Element ?
      (getNativeByTNode(hostTNode, getLViewParent(currentView) !) as RElement) :
      null;
}

/**
 * Inserts a native node before another native node for a given parent using {@link Renderer3}.
 * This is a utility function that can be used when native nodes were determined - it abstracts an
 * actual renderer being used.
 */
export function nativeInsertBefore(
    renderer: Renderer3, parent: RElement, child: RNode, beforeNode: RNode | null): void {
  ngDevMode && ngDevMode.rendererInsertBefore++;
  if (isProceduralRenderer(renderer)) {
    renderer.insertBefore(parent, child, beforeNode);
  } else {
    parent.insertBefore(child, beforeNode, true);
  }
}

function nativeAppendChild(renderer: Renderer3, parent: RElement, child: RNode): void {
  ngDevMode && ngDevMode.rendererAppendChild++;
  if (isProceduralRenderer(renderer)) {
    renderer.appendChild(parent, child);
  } else {
    parent.appendChild(child);
  }
}

function nativeAppendOrInsertBefore(
    renderer: Renderer3, parent: RElement, child: RNode, beforeNode: RNode | null) {
  if (beforeNode !== null) {
    nativeInsertBefore(renderer, parent, child, beforeNode);
  } else {
    nativeAppendChild(renderer, parent, child);
  }
}

/** Removes a node from the DOM given its native parent. */
function nativeRemoveChild(
    renderer: Renderer3, parent: RElement, child: RNode, isHostElement?: boolean): void {
  if (isProceduralRenderer(renderer)) {
    renderer.removeChild(parent, child, isHostElement);
  } else {
    parent.removeChild(child);
  }
}

/**
 * Returns a native parent of a given native node.
 */
export function nativeParentNode(renderer: Renderer3, node: RNode): RElement|null {
  return (isProceduralRenderer(renderer) ? renderer.parentNode(node) : node.parentNode) as RElement;
}

/**
 * Returns a native sibling of a given native node.
 */
export function nativeNextSibling(renderer: Renderer3, node: RNode): RNode|null {
  return isProceduralRenderer(renderer) ? renderer.nextSibling(node) : node.nextSibling;
}

/**
 * Finds a native "anchor" node for cases where we can't append a native child directly
 * (`appendChild`) and need to use a reference (anchor) node for the `insertBefore` operation.
 * @param parentTNode
 * @param lView
 */
function getNativeAnchorNode(parentTNode: TNode, lView: LView): RNode|null {
  if (parentTNode.type === TNodeType.View) {
    const lContainer = getLContainer(parentTNode as TViewNode, lView) !;
    const index = lContainer.indexOf(lView, CONTAINER_HEADER_OFFSET) - CONTAINER_HEADER_OFFSET;
    return getBeforeNodeForView(index, lContainer);
  } else if (
      parentTNode.type === TNodeType.ElementContainer ||
      parentTNode.type === TNodeType.IcuContainer) {
    return getNativeByTNode(parentTNode, lView);
  }
  return null;
}

/**
 * Appends the `child` native node (or a collection of nodes) to the `parent`.
 *
 * The element insertion might be delayed {@link canInsertNativeNode}.
 *
 * @param childEl The native child (or children) that should be appended
 * @param childTNode The TNode of the child element
 * @param currentView The current LView
 * @returns Whether or not the child was appended
 */
export function appendChild(childEl: RNode | RNode[], childTNode: TNode, currentView: LView): void {
  const renderParent = getRenderParent(childTNode, currentView);
  if (renderParent != null) {
    const renderer = currentView[RENDERER];
    const parentTNode: TNode = childTNode.parent || currentView[T_HOST] !;
    const anchorNode = getNativeAnchorNode(parentTNode, currentView);
    if (Array.isArray(childEl)) {
      for (let nativeNode of childEl) {
        nativeAppendOrInsertBefore(renderer, renderParent, nativeNode, anchorNode);
      }
    } else {
      nativeAppendOrInsertBefore(renderer, renderParent, childEl, anchorNode);
    }
  }
}

/**
 * Gets the top-level element or an ICU container if those containers are nested.
 *
 * @param tNode The starting TNode for which we should skip element and ICU containers
 * @returns The TNode of the highest level ICU container or element container
 */
function getHighestElementOrICUContainer(tNode: TNode): TNode {
  while (tNode.parent != null && (tNode.parent.type === TNodeType.ElementContainer ||
                                  tNode.parent.type === TNodeType.IcuContainer)) {
    tNode = tNode.parent;
  }
  return tNode;
}

export function getBeforeNodeForView(viewIndexInContainer: number, lContainer: LContainer): RNode {
  const nextViewIndex = CONTAINER_HEADER_OFFSET + viewIndexInContainer + 1;
  if (nextViewIndex < lContainer.length) {
    const lView = lContainer[nextViewIndex] as LView;
    ngDevMode && assertDefined(lView[T_HOST], 'Missing Host TNode');
    const tViewNodeChild = (lView[T_HOST] as TViewNode).child;
    return tViewNodeChild !== null ? getNativeByTNode(tViewNodeChild, lView) : lContainer[NATIVE];
  } else {
    return lContainer[NATIVE];
  }
}

/**
 * Removes a native node itself using a given renderer. To remove the node we are looking up its
 * parent from the native tree as not all platforms / browsers support the equivalent of
 * node.remove().
 *
 * @param renderer A renderer to be used
 * @param rNode The native node that should be removed
 * @param isHostElement A flag indicating if a node to be removed is a host of a component.
 */
export function nativeRemoveNode(renderer: Renderer3, rNode: RNode, isHostElement?: boolean): void {
  const nativeParent = nativeParentNode(renderer, rNode);
  if (nativeParent) {
    nativeRemoveChild(renderer, nativeParent, rNode, isHostElement);
  }
}

/**
 * Appends nodes to a target projection place. Nodes to insert were previously re-distribution and
 * stored on a component host level.
 * @param lView A LView where nodes are inserted (target LView)
 * @param tProjectionNode A projection node where previously re-distribution should be appended
 * (target insertion place)
 * @param selectorIndex A bucket from where nodes to project should be taken
 * @param componentView A where projectable nodes were initially created (source view)
 */
export function appendProjectedNodes(
    lView: LView, tProjectionNode: TProjectionNode, selectorIndex: number,
    componentView: LView): void {
  const projectedView = componentView[PARENT] !as LView;
  const componentNode = componentView[T_HOST] as TElementNode;
  let nodeToProject = (componentNode.projection as(TNode | null)[])[selectorIndex];

  if (Array.isArray(nodeToProject)) {
    appendChild(nodeToProject, tProjectionNode, lView);
  } else {
    while (nodeToProject) {
      if (!(nodeToProject.flags & TNodeFlags.isDetached)) {
        if (nodeToProject.type === TNodeType.Projection) {
          appendProjectedNodes(
              lView, tProjectionNode, (nodeToProject as TProjectionNode).projection,
              findComponentView(projectedView));
        } else {
          // This flag must be set now or we won't know that this node is projected
          // if the nodes are inserted into a container later.
          nodeToProject.flags |= TNodeFlags.isProjected;
          appendProjectedNode(nodeToProject, tProjectionNode, lView, projectedView);
        }
      }
      nodeToProject = nodeToProject.projectionNext;
    }
  }
}

/**
 * Loops over all children of a TNode container and appends them to the DOM
 *
 * @param ngContainerChildTNode The first child of the TNode container
 * @param tProjectionNode The projection (ng-content) TNode
 * @param currentView Current LView
 * @param projectionView Projection view (view above current)
 */
function appendProjectedChildren(
    ngContainerChildTNode: TNode | null, tProjectionNode: TNode, currentView: LView,
    projectionView: LView) {
  while (ngContainerChildTNode) {
    appendProjectedNode(ngContainerChildTNode, tProjectionNode, currentView, projectionView);
    ngContainerChildTNode = ngContainerChildTNode.next;
  }
}

/**
 * Appends a projected node to the DOM, or in the case of a projected container,
 * appends the nodes from all of the container's active views to the DOM.
 *
 * @param projectedTNode The TNode to be projected
 * @param tProjectionNode The projection (ng-content) TNode
 * @param currentView Current LView
 * @param projectionView Projection view (view above current)
 */
function appendProjectedNode(
    projectedTNode: TNode, tProjectionNode: TNode, currentView: LView,
    projectionView: LView): void {
  const native = getNativeByTNode(projectedTNode, projectionView);
  appendChild(native, tProjectionNode, currentView);

  // the projected contents are processed while in the shadow view (which is the currentView)
  // therefore we need to extract the view where the host element lives since it's the
  // logical container of the content projected views
  attachPatchData(native, projectionView);

  const nodeOrContainer = projectionView[projectedTNode.index];
  if (projectedTNode.type === TNodeType.Container) {
    // The node we are adding is a container and we are adding it to an element which
    // is not a component (no more re-projection).
    // Alternatively a container is projected at the root of a component's template
    // and can't be re-projected (as not content of any component).
    // Assign the final projection location in those cases.
    for (let i = CONTAINER_HEADER_OFFSET; i < nodeOrContainer.length; i++) {
      addRemoveViewFromContainer(nodeOrContainer[i], true, nodeOrContainer[NATIVE]);
    }
  } else if (projectedTNode.type === TNodeType.IcuContainer) {
    // The node we are adding is an ICU container which is why we also need to project all the
    // children nodes that might have been created previously and are linked to this anchor
    let ngContainerChildTNode: TNode|null = projectedTNode.child as TNode;
    appendProjectedChildren(
        ngContainerChildTNode, ngContainerChildTNode, projectionView, projectionView);
  } else {
    if (projectedTNode.type === TNodeType.ElementContainer) {
      appendProjectedChildren(projectedTNode.child, tProjectionNode, currentView, projectionView);
    }

    if (isLContainer(nodeOrContainer)) {
      appendChild(nodeOrContainer[NATIVE], tProjectionNode, currentView);
    }
  }
}


/**
 * `executeActionOnView` performs an operation on the view as specified in `action` (insert, detach,
 * destroy)
 *
 * Inserting a view without projection or containers at top level is simple. Just iterate over the
 * root nodes of the View, and for each node perform the `action`.
 *
 * Things get more complicated with containers and projections. That is because coming across:
 * - Container: implies that we have to insert/remove/destroy the views of that container as well
 *              which in turn can have their own Containers at the View roots.
 * - Projection: implies that we have to insert/remove/destroy the nodes of the projection. The
 *               complication is that the nodes we are projecting can themselves have Containers
 *               or other Projections.
 *
 * As you can see this is a very recursive problem. While the recursive implementation is not the
 * most efficient one, trying to unroll the nodes non-recursively results in very complex code that
 * is very hard (to maintain). We are sacrificing a bit of performance for readability using a
 * recursive implementation.
 *
 * @param renderer Renderer to use
 * @param action action to perform (insert, detach, destroy)
 * @param lView The LView which needs to be inserted, detached, destroyed.
 * @param renderParent parent DOM element for insertion/removal.
 * @param beforeNode Before which node the insertions should happen.
 */
function executeActionOnView(
    renderer: Renderer3, action: WalkTNodeTreeAction, lView: LView, renderParent: RElement | null,
    beforeNode: RNode | null | undefined) {
  const tView = lView[TVIEW];
  ngDevMode && assertNodeType(tView.node !, TNodeType.View);
  let viewRootTNode: TNode|null = tView.node !.child;
  while (viewRootTNode !== null) {
    executeActionOnNode(renderer, action, lView, viewRootTNode, renderParent, beforeNode);
    viewRootTNode = viewRootTNode.next;
  }
}

/**
 * `executeActionOnProjection` performs an operation on the projection specified by `action`
 * (insert, detach, destroy).
 *
 * Inserting a projection requires us to locate the projected nodes from the parent component. The
 * complication is that those nodes themselves could be re-projected from their parent component.
 *
 * @param renderer Renderer to use
 * @param action action to perform (insert, detach, destroy)
 * @param lView The LView which needs to be inserted, detached, destroyed.
 * @param renderParent parent DOM element for insertion/removal.
 * @param beforeNode Before which node the insertions should happen.
 */
function executeActionOnProjection(
    renderer: Renderer3, action: WalkTNodeTreeAction, lView: LView,
    tProjectionNode: TProjectionNode, renderParent: RElement | null,
    beforeNode: RNode | null | undefined) {
  const componentLView = findComponentView(lView);
  const componentNode = componentLView[T_HOST] as TElementNode;
  const nodeToProject = componentNode.projection ![tProjectionNode.projection] !;
  if (Array.isArray(nodeToProject)) {
    for (let i = 0; i < nodeToProject.length; i++) {
      const rNode = nodeToProject[i];
      ngDevMode && assertDomNode(rNode);
      executeActionOnElementOrContainer(action, renderer, renderParent, rNode, beforeNode);
    }
  } else {
    let projectionTNode: TNode|null = nodeToProject;
    const projectedComponentLView = componentLView[PARENT] as LView;
    while (projectionTNode !== null) {
      executeActionOnNode(
          renderer, action, projectedComponentLView, projectionTNode, renderParent, beforeNode);
      projectionTNode = projectionTNode.projectionNext;
    }
  }
}


/**
 * `executeActionOnContainer` performs an operation on the container and its views as specified by
 * `action` (insert, detach, destroy)
 *
 * Inserting a Container is complicated by the fact that the container may have Views which
 * themselves have containers or projections.
 *
 * @param renderer Renderer to use
 * @param action action to perform (insert, detach, destroy)
 * @param lContainer The LContainer which needs to be inserted, detached, destroyed.
 * @param renderParent parent DOM element for insertion/removal.
 * @param beforeNode Before which node the insertions should happen.
 */
function executeActionOnContainer(
    renderer: Renderer3, action: WalkTNodeTreeAction, lContainer: LContainer,
    renderParent: RElement | null, beforeNode: RNode | null | undefined) {
  ngDevMode && assertLContainer(lContainer);
  const anchor = lContainer[NATIVE];  // LContainer has its own before node.
  const native = unwrapRNode(lContainer);
  // An LContainer can be created dynamically on any node by injecting ViewContainerRef.
  // Asking for a ViewContainerRef on an element will result in a creation of a separate anchor node
  // (comment in the DOM) that will be different from the LContainer's host node. In this particular
  // case we need to execute action on 2 nodes:
  // - container's host node (this is done in the executeNodeAction)
  // - container's host node (this is done here)
  if (anchor !== native) {
    executeActionOnElementOrContainer(action, renderer, renderParent, anchor, beforeNode);
  }
  for (let i = CONTAINER_HEADER_OFFSET; i < lContainer.length; i++) {
    const lView = lContainer[i] as LView;
    executeActionOnView(renderer, action, lView, renderParent, anchor);
  }
}


/**
 * `executeActionOnElementContainer` performs an operation on the ng-container node and its child
 * nodes as specified by the `action` (insert, detach, destroy).
 *
 * @param renderer Renderer to use
 * @param action action to perform (insert, detach, destroy)
 * @param lView The LView which needs to be inserted, detached, destroyed.
 * @param tElementContainerNode The TNode associated with the ElementContainer.
 * @param renderParent parent DOM element for insertion/removal.
 * @param beforeNode Before which node the insertions should happen.
 */
function executeActionOnElementContainer(
    renderer: Renderer3, action: WalkTNodeTreeAction, lView: LView,
    tElementContainerNode: TElementContainerNode, renderParent: RElement | null,
    beforeNode: RNode | null | undefined) {
  const node = lView[tElementContainerNode.index];
  executeActionOnElementOrContainer(action, renderer, renderParent, node, beforeNode);
  let childTNode: TNode|null = tElementContainerNode.child;
  while (childTNode) {
    executeActionOnNode(renderer, action, lView, childTNode, renderParent, beforeNode);
    childTNode = childTNode.next;
  }
}

function executeActionOnNode(
    renderer: Renderer3, action: WalkTNodeTreeAction, lView: LView, tNode: TNode,
    renderParent: RElement | null, beforeNode: RNode | null | undefined): void {
  const elementContainerRootTNodeType = tNode.type;
  if (elementContainerRootTNodeType === TNodeType.ElementContainer) {
    executeActionOnElementContainer(
        renderer, action, lView, tNode as TElementContainerNode, renderParent, beforeNode);
  } else if (elementContainerRootTNodeType === TNodeType.Projection) {
    executeActionOnProjection(
        renderer, action, lView, tNode as TProjectionNode, renderParent, beforeNode);
  } else {
    ngDevMode && assertNodeOfPossibleTypes(tNode, TNodeType.Element, TNodeType.Container);
    executeActionOnElementOrContainer(
        action, renderer, renderParent, lView[tNode.index], beforeNode);
  }
}