@graffy/common/cjs/stream/makeWatcher.js

Common libraries that used by various Graffy modules.

"use strict";

var _interopRequireDefault = require("@babel/runtime-corejs3/helpers/interopRequireDefault");

exports.__esModule = true;
exports.default = makeWatcher;

var _bind = _interopRequireDefault(require("@babel/runtime-corejs3/core-js-stable/instance/bind"));

var _getIterator2 = _interopRequireDefault(require("@babel/runtime-corejs3/core-js/get-iterator"));

var _isArray = _interopRequireDefault(require("@babel/runtime-corejs3/core-js-stable/array/is-array"));

var _getIteratorMethod2 = _interopRequireDefault(require("@babel/runtime-corejs3/core-js/get-iterator-method"));

var _symbol = _interopRequireDefault(require("@babel/runtime-corejs3/core-js-stable/symbol"));

var _from = _interopRequireDefault(require("@babel/runtime-corejs3/core-js-stable/array/from"));

var _slice = _interopRequireDefault(require("@babel/runtime-corejs3/core-js-stable/instance/slice"));

var _promise = _interopRequireDefault(require("@babel/runtime-corejs3/core-js-stable/promise"));

var _set = _interopRequireDefault(require("@babel/runtime-corejs3/core-js-stable/set"));

var _stream = require("@graffy/stream");

function _createForOfIteratorHelperLoose(o, allowArrayLike) { var _context2; var it; if (typeof _symbol.default === "undefined" || (0, _getIteratorMethod2.default)(o) == null) { if ((0, _isArray.default)(o) || (it = _unsupportedIterableToArray(o)) || allowArrayLike && o && typeof o.length === "number") { if (it) o = it; var i = 0; return function () { if (i >= o.length) return { done: true }; return { done: false, value: o[i++] }; }; } throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); } it = (0, _getIterator2.default)(o); return (0, _bind.default)(_context2 = it.next).call(_context2, it); }

function _unsupportedIterableToArray(o, minLen) { var _context; if (!o) return; if (typeof o === "string") return _arrayLikeToArray(o, minLen); var n = (0, _slice.default)(_context = Object.prototype.toString.call(o)).call(_context, 8, -1); if (n === "Object" && o.constructor) n = o.constructor.name; if (n === "Map" || n === "Set") return (0, _from.default)(o); if (n === "Arguments" || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(n)) return _arrayLikeToArray(o, minLen); }

function _arrayLikeToArray(arr, len) { if (len == null || len > arr.length) len = arr.length; for (var i = 0, arr2 = new Array(len); i < len; i++) { arr2[i] = arr[i]; } return arr2; }

function makeWatcher() {
  var listeners = new _set.default();

  function write(change) {
    for (var _iterator = _createForOfIteratorHelperLoose(listeners), _step; !(_step = _iterator()).done;) {
      var push = _step.value;
      push(change);
    }
  }

  function watch() {
    for (var _len = arguments.length, args = new Array(_len), _key = 0; _key < _len; _key++) {
      args[_key] = arguments[_key];
    }

    return (0, _stream.makeStream)(function (push, _end) {
      listeners.add(push); // We do this instead of binding the first value to a variable
      // to decide between pushing undefined and not making a push.

      if (args.length) _promise.default.resolve(args[0]).then(push);
      return function () {
        return listeners.delete(push);
      };
    });
  }

  return {
    write: write,
    watch: watch
  };
}

module.exports = exports.default;