dmn-eval-js-es5/utils/helper/external-function.js

Evaluation of DMN 1.1 decision tables, limited to S-FEEL (Simple Friendly Enough Expression Language), es5 browser compatible

'use strict';

/*
*
*  ©2016-2017 EdgeVerve Systems Limited (a fully owned Infosys subsidiary),
*  Bangalore, India. All Rights Reserved.
*
*/

var vm = require('vm');

var callback = function callback(resolve, reject) {
  return function (err, res) {
    if (err) {
      reject(err);
    } else {
      resolve(res);
    }
  };
};

var execute = function execute(script, payload, done) {
  var sandbox = Object.assign({}, payload);
  sandbox.done = done;
  script.runInNewContext(sandbox);
};

var prepareDependencies = function prepareDependencies(dependencies) {
  var requireObj = {};
  dependencies.forEach(function (dependency) {
    Object.keys(dependency).forEach(function (key) {
      requireObj[key] = require(dependency[key]); // eslint-disable-line
    });
  });
  return requireObj;
};

var externalFn = function externalFn(bodyMeta) {
  return function (code, dependencies) {
    var script = new vm.Script(code);
    var reqdLibs = Object.assign({}, prepareDependencies(dependencies), global);
    return function (payload, done) {
      return execute(script, Object.assign({}, reqdLibs, payload), done);
    };
  }(bodyMeta.js.signature || '', bodyMeta.js.dependencies || []);
};

module.exports = function (ctx, bodyMeta) {
  return new Promise(function (resolve, reject) {
    externalFn(bodyMeta)(ctx, callback(resolve, reject));
  });
};