Question

是否可以在switch语句中包含生成器？因为在函数中可能并不总是回传生成器？

在代码中：

function* getWebsite ($) {
  const contents = $('.selector-blah');
  if (contents) {
    const resp = yield http.getHTML({ url: contents.href });
    return resp.finalUrl;
  } else {
    return null;
  }
}

const selectorMappings = {
  name: '#name',
  starRating: getStarRating, // normal function
  website: getWebsite // generator function
}

yield processSelectors($, data, selectorMappings);
// <code> here is excuting before yield is complete above.

processSelectors模块：

const _ = require('lodash');
const sanitizeText = require('./sanitizeText');

module.exports = function* processSelectors ($, data, selectors = {}, route = '') {
  const keys = Object.keys(selectors);
  for (let key of keys) {
    let path = route ? route + '.' + key : key;
    switch (selectors[key].constructor.name) {
      case 'String':
        _.set(data, path, sanitizeText($(selectors[key]).first().text()));
        break;
      case 'Function':
        _.set(data, path, selectors[key]($));
        break;
      case 'GeneratorFunction':
        var result = yield selectors[key]($);
        _.set(data, path, result);
        break;
      case 'Object':
        _.set(data, path, {});
        processSelectors($, data, selectors[key], path);
        break;
    }
  }
};

我确实在forEach中有一个开关但移出来避免嵌套函数但没有帮助，也尝试使用co和co.wrap，以及Promise的。

Answer 1

通过使整个事物成为一个发电机来实现这一点：

yield processSelectors($, data, selectorMappings);

////////////////////////////////////////////////////////
//                       MODULE                       //
////////////////////////////////////////////////////////

const _ = require('lodash');
const sanitizeText = require('./sanitizeText');

module.exports = function* processSelectors ($, data, selectors = {}, route = '') {
  const keys = Object.keys(selectors);
  for (let key of keys) {
    let path = route ? route + '.' + key : key;
    switch (selectors[key].constructor.name) {
      case 'String':
        _.set(data, path, sanitizeText($(selectors[key]).first().text()));
        break;
      case 'Function':
        _.set(data, path, selectors[key]($));
        break;
      case 'GeneratorFunction':
        _.set(data, path, yield selectors[key]($));
        break;
      case 'Object':
        _.set(data, path, {});
        processSelectors($, data, selectors[key], path);
        break;
    }
  }
};

＆＃34;可选＆＃34; switch语句中的生成器？

1 个答案: