sensitive-word-helper-plus/src/core/tree.ts

基于DFA算法的一个敏感词助手, 可以做步长控制

/**
 * Created by ChengZheLin on 2019/6/4.
 * Features: tree
 */

import Node from './node';
import { Children } from './index';

// Object兼容
if (!Object['values'])
  Object['values'] = (o: any) => Object.keys(o).map(k => o[k]);

export default class Tree {
  public root: Node;

  constructor() {
    this.root = new Node('root');
  }
  neglectwords: Array<string> = [];
  replacement: string = '*';
  step: number = 3;

  /**
   * 插入数据
   * @param key
   */
  insert(key: string): boolean {
    if (!key) return false;
    let keyArr = key.split('');
    let firstKey = keyArr.shift();
    let children = this.root.children;
    let len = keyArr.length;
    let firstNode = children[firstKey];

    // 第一个key
    if (!firstNode) {
      children[firstKey] = len
        ? new Node(firstKey)
        : new Node(firstKey, undefined, true);
    } else if (!len) {
      firstNode.word = true;
    }

    // 其他多余的key
    if (keyArr.length >= 1) {
      this.insertNode(children[firstKey], keyArr);
    }

    return true;
  }

  /**
   * 插入节点
   * @param node
   * @param word
   */
  insertNode(node: Node, word: string[]) {
    let len = word.length;

    if (len) {
      let children: Children;
      children = node.children;

      const key = word.shift();
      let item = children[key];
      const isWord = len === 1;

      if (!item) {
        item = new Node(key, node, isWord);
      }
      item.word = item.word || isWord;

      children[key] = item;
      this.insertNode(item, word);
    }
  }

  /**
   * 创建Failure表
   */
  _createFailureTable() {
    // 获取树第一层
    let currQueue: Array<Node> = Object.values(this.root.children);
    while (currQueue.length > 0) {
      let nextQueue: Array<Node> = [];
      for (let i = 0; i < currQueue.length; i++) {
        let node: Node = currQueue[i];
        let key = node.key;
        let parent = node.parent;
        node.failure = this.root;
        // 获取树下一层
        for (let k in node.children) {
          nextQueue.push(node.children[k]);
        }

        if (parent) {
          let failure: any = parent.failure;
          while (failure) {
            let children: any = failure.children[key];

            // 判断是否到了根节点
            if (children) {
              node.failure = children;
              break;
            }
            failure = failure.failure;
          }
        }
      }

      currQueue = nextQueue;
    }
  }

  /**
   * 搜索节点
   * @param key
   * @param node
   */
  search(key: string, node: Children = this.root.children): Node | undefined {
    return node[key];
  }
}