hexo.extend.filter.register('before_generate', function () {

//hexo/lib/hexo/index.js
  _generate(options = {}) {
    if (this._isGenerating) return;

    const useCache = options.cache;

    this._isGenerating = true;

    this.emit('generateBefore');

    // Run before_generate filters
    this.log.debug("YGH:data:%s", this.locals.get('data'));
    return this.execFilter('before_generate', this.locals.get('data'), { context: this })
      .then(() => this._routerReflesh(this._runGenerators(), useCache)).then(() => {
        this.emit('generateAfter');

        // Run after_generate filters
        return this.execFilter('after_generate', null, { context: this });
      }).finally(() => {
        this._isGenerating = false;
      });
  }

//hexo/lib/extend/filter.js
  exec(type, data, options = {}) {
    const filters = this.list(type);
    if (filters.length === 0) return Promise.resolve(data);

    const ctx = options.context;
    console.log("YGH:type:%s locals:%s", type, ctx.locals);
    const posts = ctx.locals.get('posts');
    if(posts)
       console.log("%s", posts);
    console.log("%s", ctx.locals.get('posts'));
    const args = options.args || [];

    args.unshift(data);

    return Promise.each(filters, filter => Reflect.apply(Promise.method(filter), ctx, args).then(result => {
      args[0] = result == null ? args[0] : result;
      return args[0];
    })).then(() => args[0]);
  }