@zkochan/pnpm/lib/node_modules/zen-push/index.js

Fast, disk space efficient package manager

'use strict';

var Observable = require('zen-observable');

function addMethods(target, methods) {
  Object.keys(methods).forEach(function(k) {
    var desc = Object.getOwnPropertyDescriptor(methods, k);
    desc.enumerable = false;
    Object.defineProperty(target, k, desc);
  });
}

function send(p, message, value) {
  if (p._observer) {
    sendMessage(p._observer, message, value);
  } else if (p._observers) {
    var list = [];
    p._observers.forEach(function(to) { list.push(to); });
    list.forEach(function(to) { sendMessage(to, message, value); });
  }
}

function sendMessage(observer, message, value) {
  if (observer.closed) {
    return;
  }
  switch (message) {
    case 'next': return observer.next(value);
    case 'error': return observer.error(value);
    case 'complete': return observer.complete(value);
  }
}

function hasObserver(p) {
  return p._observer || p._observers && p._observers.size > 0;
}

function addObserver(p, observer) {
  if (p._observers) {
    p._observers.add(observer);
  } else if (!p._observer) {
    p._observer = observer;
  } else {
    p._observers = new Set();
    p._observers.add(p._observer);
    p._observers.add(observer);
    p._observer = null;
  }
}

function deleteObserver(p, observer) {
  if (p._observers) {
    p._observers.delete(observer);
  } else if (p._observer === observer) {
    p._observer = null;
  }
}

function notifyStart(p, opts) {
  !hasObserver(p) && opts && opts.start && opts.start();
}

function notifyPause(p, opts) {
  !hasObserver(p) && opts && opts.pause && opts.pause();
}

function PushStream(opts) {
  var p = this;
  this._observer = null;
  this._observers = null;
  this._observable = new Observable(function(observer) {
    notifyStart(p, opts);
    addObserver(p, observer);
    return function() {
      deleteObserver(p, observer);
      notifyPause(p, opts);
    };
  });
}

addMethods(PushStream.prototype, {
  get observable() { return this._observable; },
  get observed() { return hasObserver(this); },
  next: function(x) { send(this, 'next', x); },
  error: function(e) { send(this, 'error', e); },
  complete: function(x) { send(this, 'complete', x); },
});

module.exports = PushStream;