kefir-process/dist/api.js

Using kefir to create communicating processes.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.createProcess = createProcess;

var _child_process = require('child_process');

var _kefir = require('kefir');

var _kefir2 = _interopRequireDefault(_kefir);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

var maxParallel = 4;

function fromMultiCallback(callbackConsumer) {
  return _kefir2.default.stream(function (emitter) {
    callbackConsumer(function (x) {
      if (x == null) {
        emitter.end();
        return;
      }
      emitter.emit(x);
    });
  });
}

function createProcess(program, args) {
  args = args || [];
  var nextCallback;
  // start maxParallel
  var canRun = _kefir2.default.merge([_kefir2.default.sequentially(0, Array(maxParallel + 1).join('a').split('')), fromMultiCallback(function (callback) {
    nextCallback = callback;
  })]);
  var inputStream = _kefir2.default.never();
  return function (value) {
    inputStream = _kefir2.default.concat([inputStream, _kefir2.default.later(1, value)]);
    var canThisRun = canRun.take(1);
    var mayRun = _kefir2.default.zip([inputStream, canThisRun]).map(function () {
      var instance = (0, _child_process.spawn)(program, args);
      return instance;
    });

    var readyCallback;
    var readyStream = _kefir2.default.fromCallback(function (callback) {
      readyCallback = callback;
    });

    var stream = _kefir2.default.stream(function (emitter) {
      mayRun.onValue(function (instance) {
        instance.stdout.on('data', function (data) {
          emitter.emit(data.toString());
        });
        instance.on('close', function () {
          emitter.end();
          nextCallback(true);
        });
        instance.stderr.on('data', function (data) {
          console.error(data.toString());
        });
        readyCallback(instance);
      });
      readyStream.onValue(function (instance) {
        instance.stdin.write('' + value);
        instance.stdin.end();
      });
    });

    return stream;
  };
}
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