jsan/lib/utils.js

handle circular references when stringifying and parsing

var pathGetter = require('./path-getter');
var jsan = require('./');

exports.getRegexFlags = function getRegexFlags(regex) {
  var flags = '';
  if (regex.ignoreCase) flags += 'i';
  if (regex.global) flags += 'g';
  if (regex.multiline) flags += 'm';
  return flags;
};

exports.stringifyFunction = function stringifyFunction(fn, customToString) {
  if (typeof customToString === 'function') {
    return customToString(fn);
  }
  var str = fn.toString();
  var match = str.match(/^[^{]*{|^[^=]*=>/);
  var start = match ? match[0] : '<function> ';
  var end = str[str.length - 1] === '}' ? '}' : '';
  return start.replace(/\r\n|\n/g, ' ').replace(/\s+/g, ' ') + ' /* ... */ ' + end;
};

exports.restore = function restore(obj, root) {
  var type = obj[0];
  var rest = obj.slice(1);
  switch(type) {
    case '$':
      return pathGetter(root, obj);
    case 'r':
      var comma = rest.indexOf(',');
      var flags = rest.slice(0, comma);
      var source = rest.slice(comma + 1);
      return RegExp(source, flags);
    case 'd':
      return new Date(+rest);
    case 'f':
      var fn = function() { throw new Error("can't run jsan parsed function") };
      fn.toString = function() { return rest; };
      return fn;
    case 'u':
      return undefined;
    case 'e':
      var error = new Error(rest);
      error.stack = 'Stack is unavailable for jsan parsed errors';
      return error;
    case 's':
      return Symbol(rest);
    case 'g':
      return Symbol.for(rest);
    case 'm':
      return new Map(jsan.parse(rest));
    case 'l':
      return new Set(jsan.parse(rest));
    case 'n':
      return NaN;
    case 'i':
      return Infinity;
    case 'y':
      return -Infinity;
    default:
      console.warn('unknown type', obj);
      return obj;
  }
}