noflo-core/components/MakeFunction.js

NoFlo Essentials

/* eslint no-new-func: "warn" */
const noflo = require('noflo');

exports.getComponent = () => {
  const c = new noflo.Component();
  c.description = `Evaluates a function each time data hits the "in" port 
and sends the return value to "out". Within the function "x" will 
be the variable from the in port. For example, to make a ^2 function 
input "return x*x;" to the function port.`;
  c.icon = 'code';

  c.inPorts.add('in', {
    datatype: 'all',
    description: 'Packet to be processed',
  });
  c.inPorts.add('function', {
    datatype: 'string',
    description: 'Function to evaluate',
    control: true,
  });
  c.outPorts.add('out', {
    datatype: 'all',
  });
  c.outPorts.add('function', {
    datatype: 'function',
  });
  c.outPorts.add('error', {
    datatype: 'object',
  });

  const prepareFunction = (func, callback) => {
    let newFunc;
    if (typeof func === 'function') {
      callback(null, func);
      return;
    }
    try {
      newFunc = Function('x', func);
    } catch (e) {
      callback(e);
      return;
    }
    callback(null, newFunc);
  };

  return c.process((input, output) => {
    if (input.attached('in').length && !input.hasData('in')) { return; }
    if (input.hasData('function', 'in')) {
      // Both function and input data
      prepareFunction(input.getData('function'), (err, func) => {
        let result;
        if (err) {
          output.done(err);
          return;
        }
        const data = input.getData('in');
        try {
          result = func(data);
        } catch (error) {
          output.done(error);
          return;
        }
        output.sendDone({
          function: func,
          out: result,
        });
      });
      return;
    }
    if (!input.hasData('function')) { return; }
    prepareFunction(input.getData('function'), (err, func) => {
      if (err) {
        output.done(err);
        return;
      }
      output.sendDone({ function: func });
    });
  });
};