Wrapper for serializing between contexts using native gc.

jswrap.js

//
// Wrap an object for another context...
// Will not wrap functions given to parent from sandbox
// Will not crawl prototypes, be explicit
// Result is not a "live" representation, if you need to sync objects you should rewrap
// DO NOT ADD/UPDATE PROPERTIES ON RESULT ONLY READ AND INVOKE
//
function wrapper() {
  var stringify = JSON.stringify,
    parse = JSON.parse,
    isArray = Array.isArrray,
    indexOf = function (arr, item) {
      "use strict";
      for (var i = 0; i < arr.length; i++) {
        if (arr[i] === item) return i;
      }
      return -1;
    }
  var comm;
  comm = {
    unwrap: function ( ) { },
    wrap: function wrap(o, visited) {
      "use strict";
      visited = visited || {};
      visited.source = visited.source || [];
      visited.callbacks = visited.callbacks || [];
      visited.result = visited.result || {};
      if (typeof o === 'function') {
        var result = function fn() {
        "use strict";
          var args = [];
          for (var i = 0; i < arguments.length; i++) {
            args[i] = comm.unwrap(arguments[i]);
          }
          //
          // this apply is outside sandbox, we are ok
          //
          return comm.unwrap(o.apply(null, args));
        }
        return result;
      }
      if (typeof o === 'object') {
        if (!o) {
          return null;
        }
        var result = {};//stringify(o)[0] === '[' ? [] : {};
        for(var key in o) {
          ;(function (key) {
            var item = o[key],
              index = indexOf(visited.source, item);
            if (index !== -1) {
              if (index in visited.result) {
                result[key] = visited.result[index];
              }
              else {
                var cbs = visited.callbacks[index] || (visited.callbacks[index] = []);
                cbs[cbs.length] = (function () {
                if(typeof console != 'undefined') console.log(index)
                  result[key] = visited.result[index];
                });
              }
            }
            else {
              var index = visited.source.length;
              visited.source[index] = o[key];
              result[key] = wrap(o[key], visited);
              visited.result[index] = result[key];
              var callbacks = visited.callbacks[index];
              if (callbacks) {
                for (var i = 0; i < callbacks.length; i++) {
                  callbacks[i]();
                }
              }
            }
          })(key);
        };
        return result;
      }
      if (typeof o === 'number') {
        return parse(stringify(o));
      }
      if (typeof o === 'boolean') {
        return parse(stringify(o));
      }
      if (typeof o === 'string') {
        return parse(stringify(o));
      }
      return undefined;
    }
  }
  return comm;
};

//
// Utility to combine a duplex wrapper
//
function getWrapper(runner) {
  var runnerFn = runner('('+wrapper.toString()+')');
  var outer_wrap = wrapper();
  var runner_wrap = runnerFn();
  outer_wrap.unwrap = runner_wrap.wrap;
  runner_wrap.unwrap = outer_wrap.wrap;
  return runner_wrap.wrap;
}
module.exports = getWrapper;