immutable-treeUtils树的理解

1、

function TreeUtils(rootPath, idKey, childNodesKey, none) {
    this.rootPath = rootPath || Seq();
    this.idKey = idKey || 'id';
    this.childNodesKey = childNodesKey || 'childNodes';
    this.none = typeof none !== 'undefined' ? none : NONE;
}

创建一个树，参数分别是一个数据类型为seq（）的根路径，id，childNodesKey(数据中的一个子数据集)

2、获取所有state数据中的child

TreeUtils.prototype.nodes = function(state, path) {
    let childNodesKey = this.childNodesKey;
    let result = List();
    let stack = List.of(path || this.rootPath);
    while (stack.size > 0) {
        var keyPath = stack.first();
        result = result.push(keyPath);

        stack = stack.shift();

        let item = state.getIn(keyPath);
        let childNodes = item.get(childNodesKey);
        if (childNodes && childNodes.size > 0) {
            item.get(childNodesKey)
                .keySeq()
                .forEach(function(i) {
                    stack = stack.push(keyPath.concat(childNodesKey, i));
                });
        }
    }

    return result;
};

3、根据id获取child

/**
 * @id TreeUtils-byId
 * @lookup byId
 *
 * #### *method* byId()
 *
 * Returns the key path to the node with id === `id`.
 *
 * ###### Signature:
 * ```js
 * id(
 * state: Immutable.Iterable,
 * id: string
 * ): Immutable.Seq<string|number>
 * ```
 *
 * ###### Arguments:
 * * `id` - A unique identifier
 *
 * ###### Returns:
 * The key path to the node with id === `id`.
 */
TreeUtils.prototype.byId = function(state, id) {
    let idKey = this.idKey;
    return this.find(state, function(item) {
        return item.get(idKey) === id;
    });
};

4、find查找，会调用treeUtils.nodes获取所有的child，从child中获取符合条件的child

/**
 * @id TreeUtils-find
 * @lookup find
 *
 * #### *method* find()
 *
 * Returns the key path to the first node for which `compatator` returns `true`. Uses >nodes internally and as >nodes is an **unordered** List, you should probably use this to find unique occurences of data.
 * ```js
 * treeUtils.find(state, node => node.get('name') === 'Me in Paris');
 * // Seq ["childNodes", 0, "childNodes", 0]
 * ```
 *
 * ###### Signature:
 * ```js
 * find(
 * state: Immutable.Iterable,
 * comparator: (
 * node: Immutable.Iterable,
 * keyPath: Immutable.Seq<string|number>
 * ): boolean,
 * path?: Immutable.Seq<string|number>
 * ): Immutable.Seq<string|number>
 * ```
 *
 * ###### Arguments:
 * * `comparator` - A function that gets passed a `node` and its `keyPath` and should return whether it fits the criteria or not.
 * * `path?` - An optional key path to the (sub)state you want to analyse: Default: The `TreeUtils` object's `rootPath`.
 *
 * ###### Returns:
 * The key path to the first node for which `comparator` returned `true`.
 */
TreeUtils.prototype.find = function(state, comparator, path) {
    return this.nodes(state, path).find(
        function(keyPath) {
            return comparator(state.getIn(keyPath), keyPath) === true;
        },
        this,
        this.none
    );
};