jsnetworkx/node/contrib/observer.js

A graph processing and visualization library for JavaScript (port of NetworkX for Python).

'use strict';

var _createClass = require('babel-runtime/helpers/create-class')['default'];

var _classCallCheck = require('babel-runtime/helpers/class-call-check')['default'];

var _getIterator = require('babel-runtime/core-js/get-iterator')['default'];

var _Array$from = require('babel-runtime/core-js/array/from')['default'];

Object.defineProperty(exports, '__esModule', {
  value: true
});
exports.observe = observe;
exports.unobserve = unobserve;
exports.isObservable = isObservable;
/**
 * A simple event object to any data can be added. It provides four methods:
 *
 * - stopPropagation to indicated that subsequent event handlers should not be
 *   executed.
 * - isPropgationStopped to test the status (internal only)
 * - preventDefault to prevent the default action
 * - isDefaultPrevented to test the status
 */

var Event = (function () {

  /**
   * @param {string} type
   * @param {*} target
   */

  function Event(type, target) {
    _classCallCheck(this, Event);

    this.type = type;
    this.target = target;
    this._defaultAction = true;
    this._propagate = true;
  }

  _createClass(Event, [{
    key: 'stopPropagation',

    /**
     * When called, should prevent the execution of subsequent handlers.
     */
    value: function stopPropagation() {
      this._propagate = false;
    }
  }, {
    key: 'isPropgationStopped',

    /**
     * Tests whether the propagation should be stopped.
     * @return {boolean}
     */
    value: function isPropgationStopped() {
      return !this._propagate;
    }
  }, {
    key: 'preventDefault',

    /**
     * When called, should prevent the default action.
     */
    value: function preventDefault() {
      this._defaultAction = false;
    }
  }, {
    key: 'isDefaultPrevented',

    /**
     * Tests whether the default action should be stopped.
     *
     * @return {boolean}
     */
    value: function isDefaultPrevented() {
      return !this._defaultAction;
    }
  }]);

  return Event;
})();

/**
 * Makes a graph observable, i.e. external code can bind event handlers to
 * be notified about changes in the graph (adding or removing nodes or edges).
 *
 * @param {Graph} G The graph to make observable
 * @return {Graph} The same graph passed as argument (not a new graph)
 */

function observe(G) {
  if (typeof G.on === 'function') {
    // graph is already observable, do nothing
    return G;
  }

  var eventHandlers = {
    'addNodes': [],
    'removeNodes': [],
    'addEdges': [],
    'removeEdges': [],
    'clear': []
  };
  var proto = G.constructor.prototype;

  /* eslint-disable no-shadow */
  function triggerHandlers(event, G, funcName, args) {
    /* eslint-enable no-shadow */
    var handlers = eventHandlers[event.type];
    if (!handlers) {
      return;
    }
    // run before handlers
    for (var i = 0, l = handlers.length; i < l && !event.isPropgationStopped(); i += 3) {
      if (handlers[i + 2]) {
        handlers[i].call(handlers[i + 1] || G, event);
      }
    }

    if (!event.isDefaultPrevented()) {
      if (args) {
        proto[funcName].apply(G, args);
      } else {
        proto[funcName].call(G);
      }
      if (!event.isPropgationStopped()) {
        // run after handlers
        for (i = 0, l = handlers.length; i < l && !event.isPropgationStopped(); i += 3) {
          if (!handlers[i + 2]) {
            handlers[i].call(handlers[i + 1] || G, event);
          }
        }
      }
    }
  }

  G.on = function (event, handler, thisObj, before) {
    if (!eventHandlers[event]) {
      throw new Error('Event "' + event + '" is not supported.');
    }
    eventHandlers[event].push(handler, thisObj, !!before);
  };

  G.off = function (event, handler, thisObj) {
    var handlers;
    var startIndex;
    var i;
    if (arguments.length === 1) {
      // Remove all event handlers
      eventHandlers[event].length = 0;
    } else if (arguments.length === 2) {
      // Remove particular handler or object only
      handlers = eventHandlers[event];
      startIndex = handlers.length - 2;
      if (typeof handler !== 'function') {
        startIndex += 1;
      }
      for (i = startIndex; i > 0; i -= 2) {
        if (handlers[i] === handler) {
          handlers.splice(i, 3);
        }
      }
    } else {
      // Remove particular handler-object combination
      handlers = eventHandlers[event];
      startIndex = handlers.length - 2;
      for (i = startIndex; i > 0; i -= 2) {
        if (handlers[i] === handler && handlers[i + 1] === thisObj) {
          handlers.splice(i, 2);
        }
      }
    }
  };

  G.addNode = function (n) {
    var newNodes = G.hasNode(n) ? [] : [n];
    var event = new Event('addNodes', this);
    event.nodes = [n];
    event.newNodes = newNodes;

    triggerHandlers(event, this, 'addNode', arguments);
  };

  G.addNodesFrom = function (nbunch) {
    var nodes = [];
    var newNodes = [];

    var _iteratorNormalCompletion = true;
    var _didIteratorError = false;
    var _iteratorError = undefined;

    try {
      for (var _iterator = _getIterator(nbunch), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
        var bunch = _step.value;

        var v = Array.isArray(bunch) ? bunch[0] : bunch;
        nodes.push(Array.isArray(bunch) ? bunch.slice() : bunch);
        if (!G.hasNode(v)) {
          newNodes.push(v);
        }
      }
    } catch (err) {
      _didIteratorError = true;
      _iteratorError = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion && _iterator['return']) {
          _iterator['return']();
        }
      } finally {
        if (_didIteratorError) {
          throw _iteratorError;
        }
      }
    }

    var event = new Event('addNodes', this);
    event.nodes = nodes.filter(function (v) {
      return Array.isArray(v) ? v[0] : v;
    });
    event.newNodes = newNodes;

    var args = _Array$from(arguments);
    args[0] = nodes;

    triggerHandlers(event, this, 'addNodesFrom', args);
  };

  G.addEdge = function (u, v) {
    var edges = [[u, v]];
    var newEdges = this.hasEdge(u, v) ? [] : edges;

    var event = new Event('addEdges', this);
    event.edges = edges;
    event.newEdges = newEdges;

    triggerHandlers(event, this, 'addEdge', arguments);
  };

  G.addEdgesFrom = function (ebunch) {
    var edges = [];
    var newEdges = [];
    var _iteratorNormalCompletion2 = true;
    var _didIteratorError2 = false;
    var _iteratorError2 = undefined;

    try {
      for (var _iterator2 = _getIterator(ebunch), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
        var bunch = _step2.value;

        edges.push(bunch.slice());
        if (!this.hasEdge(bunch[0], bunch[1])) {
          newEdges.push(bunch.slice(0, 2));
        }
      }
    } catch (err) {
      _didIteratorError2 = true;
      _iteratorError2 = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion2 && _iterator2['return']) {
          _iterator2['return']();
        }
      } finally {
        if (_didIteratorError2) {
          throw _iteratorError2;
        }
      }
    }

    var event = new Event('addEdges', this);
    event.edges = edges;
    event.newEdges = newEdges;

    var args = _Array$from(arguments);
    args[0] = edges;

    triggerHandlers(event, this, 'addEdgesFrom', args);
  };

  G.removeNode = function (n) {
    var event = new Event('removeNodes', this);
    event.nodes = [n];

    triggerHandlers(event, this, 'removeNode', arguments);
  };

  G.removeNodesFrom = function (nbunch) {
    var nodes = [];
    var _iteratorNormalCompletion3 = true;
    var _didIteratorError3 = false;
    var _iteratorError3 = undefined;

    try {
      for (var _iterator3 = _getIterator(nbunch), _step3; !(_iteratorNormalCompletion3 = (_step3 = _iterator3.next()).done); _iteratorNormalCompletion3 = true) {
        var bunch = _step3.value;

        nodes.push(Array.isArray(bunch) ? bunch.slice() : bunch);
      }
    } catch (err) {
      _didIteratorError3 = true;
      _iteratorError3 = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion3 && _iterator3['return']) {
          _iterator3['return']();
        }
      } finally {
        if (_didIteratorError3) {
          throw _iteratorError3;
        }
      }
    }

    var event = new Event('removeNodes', this);
    event.nodes = nodes;

    var args = _Array$from(arguments);
    args[0] = nodes;

    triggerHandlers(event, this, 'removeNodesFrom', args);
  };

  G.removeEdge = function (u, v) {
    var event = new Event('removeEdges', this);
    event.edges = [[u, v]];

    triggerHandlers(event, this, 'removeEdge', arguments);
  };

  G.removeEdgesFrom = function (ebunch) {
    var edges = [];
    var _iteratorNormalCompletion4 = true;
    var _didIteratorError4 = false;
    var _iteratorError4 = undefined;

    try {
      for (var _iterator4 = _getIterator(ebunch), _step4; !(_iteratorNormalCompletion4 = (_step4 = _iterator4.next()).done); _iteratorNormalCompletion4 = true) {
        var bunch = _step4.value;

        edges.push(bunch.slice());
      }
    } catch (err) {
      _didIteratorError4 = true;
      _iteratorError4 = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion4 && _iterator4['return']) {
          _iterator4['return']();
        }
      } finally {
        if (_didIteratorError4) {
          throw _iteratorError4;
        }
      }
    }

    var event = new Event('removeEdges');
    event.edges = edges;

    var args = _Array$from(arguments);
    args[0] = edges;

    triggerHandlers(event, this, 'removeEdgesFrom', args);
  };

  G.clear = function () {
    triggerHandlers(new Event('clear', this), this, 'clear');
  };

  return G;
}

/**
 * Removes the properties added to a graph for event handling.
 *
 * @param {Graph} G
 * @return {Graph} The graph passed to the function
 */

function unobserve(G) {
  var proto = G.constructor.prototype;

  if (typeof G.on !== 'function') {
    // nothing to do
    return G;
  }

  G.addNode = proto.addNode;
  G.addNodesFrome = proto.addNodesFrom;
  G.addEdge = proto.addEdge;
  G.addEdgesFrome = proto.addEdgesFrom;
  G.removeNode = proto.removeNode;
  G.removeEdge = proto.removeEdge;
  G.removeNodesFrom = proto.removeNodesFrom;
  G.removeEdgesFrom = proto.removeEdgesFrom;
  G.clear = proto.clear;

  delete G.on;
  delete G.off;

  return G;
}

/**
 * Tests whether the graph is observable.
 *
 * @param {Graph} G
 * @return {boolean}
 */

function isObservable(G) {
  return typeof G.on === 'function' && typeof G.off === 'function';
}