#

API Docs for: v2.11.1
Show: Inherited Protected Private Deprecated

# File: node_modules/rsvp/lib/rsvp/node.js

    import Promise from './promise';
    import {
      noop,
      resolve,
      reject
    } from './-internal';
    import { isArray } from './utils';

    function Result() {
      this.value = undefined;
    }

    const ERROR = new Result();
    const GET_THEN_ERROR = new Result();

    function getThen(obj) {
      try {
       return obj.then;
      } catch(error) {
        ERROR.value= error;
        return ERROR;
      }
    }

    function tryApply(f, s, a) {
      try {
        f.apply(s, a);
      } catch(error) {
        ERROR.value = error;
        return ERROR;
      }
    }

    function makeObject(_, argumentNames) {
      let obj = {};
      let length = _.length;
      let args = new Array(length);

      for (let x = 0; x < length; x++) {
        args[x] = _[x];
      }

      for (let i = 0; i < argumentNames.length; i++) {
        let name = argumentNames[i];
        obj[name] = args[i + 1];
      }

      return obj;
    }

    function arrayResult(_) {
      let length = _.length;
      let args = new Array(length - 1);

      for (let i = 1; i < length; i++) {
        args[i - 1] = _[i];
      }

      return args;
    }

    function wrapThenable(then, promise) {
      return {
        then: function(onFulFillment, onRejection) {
          return then.call(promise, onFulFillment, onRejection);
        }
      };
    }

    /**
      `RSVP.denodeify` takes a 'node-style' function and returns a function that
      will return an `RSVP.Promise`. You can use `denodeify` in Node.js or the
      browser when you'd prefer to use promises over using callbacks. For example,
      `denodeify` transforms the following:

      ```javascript
      let fs = require('fs');

      fs.readFile('myfile.txt', function(err, data){
        if (err) return handleError(err);
        handleData(data);
      });
      ```

      into:

      ```javascript
      let fs = require('fs');
      let readFile = RSVP.denodeify(fs.readFile);

      readFile('myfile.txt').then(handleData, handleError);
      ```

      If the node function has multiple success parameters, then `denodeify`
      just returns the first one:

      ```javascript
      let request = RSVP.denodeify(require('request'));

      request('http://example.com').then(function(res) {
        // ...
      });
      ```

      However, if you need all success parameters, setting `denodeify`'s
      second parameter to `true` causes it to return all success parameters
      as an array:

      ```javascript
      let request = RSVP.denodeify(require('request'), true);

      request('http://example.com').then(function(result) {
        // result[0] -> res
        // result[1] -> body
      });
      ```

      Or if you pass it an array with names it returns the parameters as a hash:

      ```javascript
      let request = RSVP.denodeify(require('request'), ['res', 'body']);

      request('http://example.com').then(function(result) {
        // result.res
        // result.body
      });
      ```

      Sometimes you need to retain the `this`:

      ```javascript
      let app = require('express')();
      let render = RSVP.denodeify(app.render.bind(app));
      ```

      The denodified function inherits from the original function. It works in all
      environments, except IE 10 and below. Consequently all properties of the original
      function are available to you. However, any properties you change on the
      denodeified function won't be changed on the original function. Example:

      ```javascript
      let request = RSVP.denodeify(require('request')),
          cookieJar = request.jar(); // <- Inheritance is used here

      request('http://example.com', {jar: cookieJar}).then(function(res) {
        // cookieJar.cookies holds now the cookies returned by example.com
      });
      ```

      Using `denodeify` makes it easier to compose asynchronous operations instead
      of using callbacks. For example, instead of:

      ```javascript
      let fs = require('fs');

      fs.readFile('myfile.txt', function(err, data){
        if (err) { ... } // Handle error
        fs.writeFile('myfile2.txt', data, function(err){
          if (err) { ... } // Handle error
          console.log('done')
        });
      });
      ```

      you can chain the operations together using `then` from the returned promise:

      ```javascript
      let fs = require('fs');
      let readFile = RSVP.denodeify(fs.readFile);
      let writeFile = RSVP.denodeify(fs.writeFile);

      readFile('myfile.txt').then(function(data){
        return writeFile('myfile2.txt', data);
      }).then(function(){
        console.log('done')
      }).catch(function(error){
        // Handle error
      });
      ```

      @method denodeify
      @static
      @for RSVP
      @param {Function} nodeFunc a 'node-style' function that takes a callback as
      its last argument. The callback expects an error to be passed as its first
      argument (if an error occurred, otherwise null), and the value from the
      operation as its second argument ('function(err, value){ }').
      @param {Boolean|Array} [options] An optional paramter that if set
      to `true` causes the promise to fulfill with the callback's success arguments
      as an array. This is useful if the node function has multiple success
      paramters. If you set this paramter to an array with names, the promise will
      fulfill with a hash with these names as keys and the success parameters as
      values.
      @return {Function} a function that wraps `nodeFunc` to return an
      `RSVP.Promise`
      @static
    */
    export default function denodeify(nodeFunc, options) {
      let fn = function() {
        let self = this;
        let l = arguments.length;
        let args = new Array(l + 1);
        let promiseInput = false;

        for (let i = 0; i < l; ++i) {
          let arg = arguments[i];

          if (!promiseInput) {
            // TODO: clean this up
            promiseInput = needsPromiseInput(arg);
            if (promiseInput === GET_THEN_ERROR) {
              let p = new Promise(noop);
              reject(p, GET_THEN_ERROR.value);
              return p;
            } else if (promiseInput && promiseInput !== true) {
              arg = wrapThenable(promiseInput, arg);
            }
          }
          args[i] = arg;
        }

        let promise = new Promise(noop);

        args[l] = function(err, val) {
          if (err)
            reject(promise, err);
          else if (options === undefined)
            resolve(promise, val);
          else if (options === true)
            resolve(promise, arrayResult(arguments));
          else if (isArray(options))
            resolve(promise, makeObject(arguments, options));
          else
            resolve(promise, val);
        };

        if (promiseInput) {
          return handlePromiseInput(promise, args, nodeFunc, self);
        } else {
          return handleValueInput(promise, args, nodeFunc, self);
        }
      };

      fn.__proto__ = nodeFunc;

      return fn;
    }

    function handleValueInput(promise, args, nodeFunc, self) {
      let result = tryApply(nodeFunc, self, args);
      if (result === ERROR) {
        reject(promise, result.value);
      }
      return promise;
    }

    function handlePromiseInput(promise, args, nodeFunc, self){
      return Promise.all(args).then(args => {
        let result = tryApply(nodeFunc, self, args);
        if (result === ERROR) {
          reject(promise, result.value);
        }
        return promise;
      });
    }

    function needsPromiseInput(arg) {
      if (arg && typeof arg === 'object') {
        if (arg.constructor === Promise) {
          return true;
        } else {
          return getThen(arg);
        }
      } else {
        return false;
      }
    }