react-dom/lib/ReactTreeTraversal.js

React package for working with the DOM.

/**
 * Copyright 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 */

'use strict';

var _require = require('./ReactTypeOfWork'),
    HostComponent = _require.HostComponent;

var _require2 = require('./EventPluginUtils'),
    getNodeFromInstance = _require2.getNodeFromInstance,
    getInstanceFromNode = _require2.getInstanceFromNode;

function getParent(inst) {
  if (inst._hostParent !== undefined) {
    return inst._hostParent;
  }
  if (typeof inst.tag === 'number') {
    do {
      inst = inst['return'];
      // TODO: If this is a HostRoot we might want to bail out.
      // That is depending on if we want nested subtrees (layers) to bubble
      // events to their parent. We could also go through parentNode on the
      // host node but that wouldn't work for React Native and doesn't let us
      // do the portal feature.
    } while (inst && inst.tag !== HostComponent);
    // Going through the Host Node will guarantee that we get the "current"
    // Fiber, instead of the alternate because that pointer is updated when
    // props update.
    // TODO: This is a bit hacky and possibly slow. We should ideally have
    // something in the reconciler that allow us to do this safely.
    if (inst) {
      return getInstanceFromNode(getNodeFromInstance(inst));
    }
  }
  return null;
}

/**
 * Return the lowest common ancestor of A and B, or null if they are in
 * different trees.
 */
function getLowestCommonAncestor(instA, instB) {
  var depthA = 0;
  for (var tempA = instA; tempA; tempA = getParent(tempA)) {
    depthA++;
  }
  var depthB = 0;
  for (var tempB = instB; tempB; tempB = getParent(tempB)) {
    depthB++;
  }

  // If A is deeper, crawl up.
  while (depthA - depthB > 0) {
    instA = getParent(instA);
    depthA--;
  }

  // If B is deeper, crawl up.
  while (depthB - depthA > 0) {
    instB = getParent(instB);
    depthB--;
  }

  // Walk in lockstep until we find a match.
  var depth = depthA;
  while (depth--) {
    if (instA === instB) {
      return instA;
    }
    instA = getParent(instA);
    instB = getParent(instB);
  }
  return null;
}

/**
 * Return if A is an ancestor of B.
 */
function isAncestor(instA, instB) {
  while (instB) {
    if (instB === instA) {
      return true;
    }
    instB = getParent(instB);
  }
  return false;
}

/**
 * Return the parent instance of the passed-in instance.
 */
function getParentInstance(inst) {
  return getParent(inst);
}

/**
 * Simulates the traversal of a two-phase, capture/bubble event dispatch.
 */
function traverseTwoPhase(inst, fn, arg) {
  var path = [];
  while (inst) {
    path.push(inst);
    inst = getParent(inst);
  }
  var i;
  for (i = path.length; i-- > 0;) {
    fn(path[i], 'captured', arg);
  }
  for (i = 0; i < path.length; i++) {
    fn(path[i], 'bubbled', arg);
  }
}

/**
 * Traverses the ID hierarchy and invokes the supplied `cb` on any IDs that
 * should would receive a `mouseEnter` or `mouseLeave` event.
 *
 * Does not invoke the callback on the nearest common ancestor because nothing
 * "entered" or "left" that element.
 */
function traverseEnterLeave(from, to, fn, argFrom, argTo) {
  var common = from && to ? getLowestCommonAncestor(from, to) : null;
  var pathFrom = [];
  while (from && from !== common) {
    pathFrom.push(from);
    from = getParent(from);
  }
  var pathTo = [];
  while (to && to !== common) {
    pathTo.push(to);
    to = getParent(to);
  }
  var i;
  for (i = 0; i < pathFrom.length; i++) {
    fn(pathFrom[i], 'bubbled', argFrom);
  }
  for (i = pathTo.length; i-- > 0;) {
    fn(pathTo[i], 'captured', argTo);
  }
}

module.exports = {
  isAncestor: isAncestor,
  getLowestCommonAncestor: getLowestCommonAncestor,
  getParentInstance: getParentInstance,
  traverseTwoPhase: traverseTwoPhase,
  traverseEnterLeave: traverseEnterLeave
};