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78 lines
2.3 KiB
78 lines
2.3 KiB
import Queue from './structs/queue';
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import { getNeighbors } from './util';
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/**
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*
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* @param callbacks
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* allowTraversal: 确定 BFS 是否从顶点沿着边遍历到其邻居，默认情况下，同一个节点只能遍历一次
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* enterNode: 当 BFS 访问某个节点时调用
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* leaveNode: 当 BFS 访问访问结束某个节点时调用
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*/
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function initCallbacks(callbacks) {
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if (callbacks === void 0) {
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callbacks = {};
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}
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var initiatedCallback = callbacks;
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var stubCallback = function stubCallback() {};
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var allowTraversalCallback = function () {
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var seen = {};
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return function (_a) {
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var next = _a.next;
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var id = next;
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if (!seen[id]) {
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seen[id] = true;
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return true;
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}
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return false;
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};
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}();
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initiatedCallback.allowTraversal = callbacks.allowTraversal || allowTraversalCallback;
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initiatedCallback.enter = callbacks.enter || stubCallback;
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initiatedCallback.leave = callbacks.leave || stubCallback;
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return initiatedCallback;
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}
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/**
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* 广度优先遍历图
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* @param graph Graph 图实例
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* @param startNode 开始遍历的节点
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* @param originalCallbacks 回调
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*/
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var breadthFirstSearch = function breadthFirstSearch(graphData, startNodeId, originalCallbacks, directed) {
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if (directed === void 0) {
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directed = true;
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}
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var callbacks = initCallbacks(originalCallbacks);
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var nodeQueue = new Queue();
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var _a = graphData.edges,
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edges = _a === void 0 ? [] : _a;
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// 初始化队列元素
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nodeQueue.enqueue(startNodeId);
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var previousNode = '';
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var _loop_1 = function _loop_1() {
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var currentNode = nodeQueue.dequeue();
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callbacks.enter({
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current: currentNode,
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previous: previousNode
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});
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// 将所有邻居添加到队列中以便遍历
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getNeighbors(currentNode, edges, directed ? 'target' : undefined).forEach(function (nextNode) {
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if (callbacks.allowTraversal({
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previous: previousNode,
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current: currentNode,
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next: nextNode
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})) {
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nodeQueue.enqueue(nextNode);
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}
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});
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callbacks.leave({
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current: currentNode,
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previous: previousNode
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});
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// 下一次循环之前存储当前顶点
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previousNode = currentNode;
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};
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// 遍历队列中的所有顶点
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while (!nodeQueue.isEmpty()) {
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_loop_1();
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}
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};
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export default breadthFirstSearch;
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