thoughts/node_modules/mongoose/lib/utils.js

/*!
 * Module dependencies.
 */

var ReadPref = require('mongodb').ReadPreference
  , ObjectId = require('./types/objectid')
  , cloneRegExp = require('regexp-clone')
  , sliced = require('sliced')
  , mpath = require('mpath')
  , ms = require('ms')
  , MongooseBuffer
  , MongooseArray
  , Document

/*!
 * Produces a collection name from model `name`.
 *
 * @param {String} name a model name
 * @return {String} a collection name
 * @api private
 */

exports.toCollectionName = function (name) {
  if ('system.profile' === name) return name;
  if ('system.indexes' === name) return name;
  return pluralize(name.toLowerCase());
};

/**
 * Pluralization rules.
 *
 * These rules are applied while processing the argument to `toCollectionName`.
 *
 * @deprecated remove in 4.x gh-1350
 */

exports.pluralization = [
  [/(m)an$/gi, '$1en'],
  [/(pe)rson$/gi, '$1ople'],
  [/(child)$/gi, '$1ren'],
  [/^(ox)$/gi, '$1en'],
  [/(ax|test)is$/gi, '$1es'],
  [/(octop|vir)us$/gi, '$1i'],
  [/(alias|status)$/gi, '$1es'],
  [/(bu)s$/gi, '$1ses'],
  [/(buffal|tomat|potat)o$/gi, '$1oes'],
  [/([ti])um$/gi, '$1a'],
  [/sis$/gi, 'ses'],
  [/(?:([^f])fe|([lr])f)$/gi, '$1$2ves'],
  [/(hive)$/gi, '$1s'],
  [/([^aeiouy]|qu)y$/gi, '$1ies'],
  [/(x|ch|ss|sh)$/gi, '$1es'],
  [/(matr|vert|ind)ix|ex$/gi, '$1ices'],
  [/([m|l])ouse$/gi, '$1ice'],
  [/(quiz)$/gi, '$1zes'],
  [/s$/gi, 's'],
  [/$/gi, 's']
];
var rules = exports.pluralization;

/**
 * Uncountable words.
 *
 * These words are applied while processing the argument to `toCollectionName`.
 * @api public
 */

exports.uncountables = [
  'advice',
  'energy',
  'excretion',
  'digestion',
  'cooperation',
  'health',
  'justice',
  'labour',
  'machinery',
  'equipment',
  'information',
  'pollution',
  'sewage',
  'paper',
  'money',
  'species',
  'series',
  'rain',
  'rice',
  'fish',
  'sheep',
  'moose',
  'deer',
  'news',
  'expertise',
  'status',
  'media'
];
var uncountables = exports.uncountables;

/*!
 * Pluralize function.
 *
 * @author TJ Holowaychuk (extracted from _ext.js_)
 * @param {String} string to pluralize
 * @api private
 */

function pluralize (str) {
  var rule, found;
  if (!~uncountables.indexOf(str.toLowerCase())){
    found = rules.filter(function(rule){
      return str.match(rule[0]);
    });
    if (found[0]) return str.replace(found[0][0], found[0][1]);
  }
  return str;
};

/*!
 * Determines if `a` and `b` are deep equal.
 *
 * Modified from node/lib/assert.js
 *
 * @param {any} a a value to compare to `b`
 * @param {any} b a value to compare to `a`
 * @return {Boolean}
 * @api private
 */

exports.deepEqual = function deepEqual (a, b) {
  if (a === b) return true;

  if (a instanceof Date && b instanceof Date)
    return a.getTime() === b.getTime();

  if (a instanceof ObjectId && b instanceof ObjectId) {
    return a.toString() === b.toString();
  }

  if (a instanceof RegExp && b instanceof RegExp) {
    return a.source == b.source &&
           a.ignoreCase == b.ignoreCase &&
           a.multiline == b.multiline &&
           a.global == b.global;
  }

  if (typeof a !== 'object' && typeof b !== 'object')
    return a == b;

  if (a === null || b === null || a === undefined || b === undefined)
    return false

  if (a.prototype !== b.prototype) return false;

  // Handle MongooseNumbers
  if (a instanceof Number && b instanceof Number) {
    return a.valueOf() === b.valueOf();
  }

  if (Buffer.isBuffer(a)) {
    if (!Buffer.isBuffer(b)) return false;
    if (a.length !== b.length) return false;
    for (var i = 0, len = a.length; i < len; ++i) {
      if (a[i] !== b[i]) return false;
    }
    return true;
  }

  if (isMongooseObject(a)) a = a.toObject();
  if (isMongooseObject(b)) b = b.toObject();

  try {
    var ka = Object.keys(a),
        kb = Object.keys(b),
        key, i;
  } catch (e) {//happens when one is a string literal and the other isn't
    return false;
  }

  // having the same number of owned properties (keys incorporates
  // hasOwnProperty)
  if (ka.length != kb.length)
    return false;

  //the same set of keys (although not necessarily the same order),
  ka.sort();
  kb.sort();

  //~~~cheap key test
  for (i = ka.length - 1; i >= 0; i--) {
    if (ka[i] != kb[i])
      return false;
  }

  //equivalent values for every corresponding key, and
  //~~~possibly expensive deep test
  for (i = ka.length - 1; i >= 0; i--) {
    key = ka[i];
    if (!deepEqual(a[key], b[key])) return false;
  }

  return true;
};

/*!
 * Object clone with Mongoose natives support.
 *
 * If options.minimize is true, creates a minimal data object. Empty objects and undefined values will not be cloned. This makes the data payload sent to MongoDB as small as possible.
 *
 * Functions are never cloned.
 *
 * @param {Object} obj the object to clone
 * @param {Object} options
 * @return {Object} the cloned object
 * @api private
 */

exports.clone = function clone (obj, options) {
  if (obj === undefined || obj === null)
    return obj;

  if (Array.isArray(obj))
    return cloneArray(obj, options);

  if (isMongooseObject(obj)) {
    if (options && options.json && 'function' === typeof obj.toJSON) {
      return obj.toJSON(options);
    } else {
      return obj.toObject(options);
    }
  }

  if (obj.constructor) {
    switch (obj.constructor.name) {
      case 'Object':
        return cloneObject(obj, options);
      case 'Date':
        return new obj.constructor(+obj);
      case 'RegExp':
        return cloneRegExp(obj);
      default:
        // ignore
        break;
    }
  }

  if (obj instanceof ObjectId)
    return new ObjectId(obj.id);

  if (!obj.constructor && exports.isObject(obj)) {
    // object created with Object.create(null)
    return cloneObject(obj, options);
  }

  if (obj.valueOf)
    return obj.valueOf();
};
var clone = exports.clone;

/*!
 * ignore
 */

function cloneObject (obj, options) {
  var retainKeyOrder = options && options.retainKeyOrder
    , minimize = options && options.minimize
    , ret = {}
    , hasKeys
    , keys
    , val
    , k
    , i

  if (retainKeyOrder) {
    for (k in obj) {
      val = clone(obj[k], options);

      if (!minimize || ('undefined' !== typeof val)) {
        hasKeys || (hasKeys = true);
        ret[k] = val;
      }
    }
  } else {
    // faster

    keys = Object.keys(obj);
    i = keys.length;

    while (i--) {
      k = keys[i];
      val = clone(obj[k], options);

      if (!minimize || ('undefined' !== typeof val)) {
        if (!hasKeys) hasKeys = true;
        ret[k] = val;
      }
    }
  }

  return minimize
    ? hasKeys && ret
    : ret;
};

function cloneArray (arr, options) {
  var ret = [];
  for (var i = 0, l = arr.length; i < l; i++)
    ret.push(clone(arr[i], options));
  return ret;
};

/*!
 * Shallow copies defaults into options.
 *
 * @param {Object} defaults
 * @param {Object} options
 * @return {Object} the merged object
 * @api private
 */

exports.options = function (defaults, options) {
  var keys = Object.keys(defaults)
    , i = keys.length
    , k ;

  options = options || {};

  while (i--) {
    k = keys[i];
    if (!(k in options)) {
      options[k] = defaults[k];
    }
  }

  return options;
};

/*!
 * Generates a random string
 *
 * @api private
 */

exports.random = function () {
  return Math.random().toString().substr(3);
};

/*!
 * Merges `from` into `to` without overwriting existing properties.
 *
 * @param {Object} to
 * @param {Object} from
 * @api private
 */

exports.merge = function merge (to, from) {
  var keys = Object.keys(from)
    , i = keys.length
    , key

  while (i--) {
    key = keys[i];
    if ('undefined' === typeof to[key]) {
      to[key] = from[key];
    } else {
      if (exports.isObject(from[key])) {
        merge(to[key], from[key]);
      } else {
        to[key] = from[key];
      }
    }
  }
};

/*!
 * toString helper
 */

var toString = Object.prototype.toString;

/*!
 * Determines if `arg` is an object.
 *
 * @param {Object|Array|String|Function|RegExp|any} arg
 * @api private
 * @return {Boolean}
 */

exports.isObject = function (arg) {
  return '[object Object]' == toString.call(arg);
}

/*!
 * A faster Array.prototype.slice.call(arguments) alternative
 * @api private
 */

exports.args = sliced;

/*!
 * process.nextTick helper.
 *
 * Wraps `callback` in a try/catch + nextTick.
 *
 * node-mongodb-native has a habit of state corruption when an error is immediately thrown from within a collection callback.
 *
 * @param {Function} callback
 * @api private
 */

exports.tick = function tick (callback) {
  if ('function' !== typeof callback) return;
  return function () {
    try {
      callback.apply(this, arguments);
    } catch (err) {
      // only nextTick on err to get out of
      // the event loop and avoid state corruption.
      process.nextTick(function () {
        throw err;
      });
    }
  }
}

/*!
 * Returns if `v` is a mongoose object that has a `toObject()` method we can use.
 *
 * This is for compatibility with libs like Date.js which do foolish things to Natives.
 *
 * @param {any} v
 * @api private
 */

exports.isMongooseObject = function (v) {
  Document || (Document = require('./document'));
  MongooseArray || (MongooseArray = require('./types').Array);
  MongooseBuffer || (MongooseBuffer = require('./types').Buffer);

  return v instanceof Document ||
         v instanceof MongooseArray ||
         v instanceof MongooseBuffer
}
var isMongooseObject = exports.isMongooseObject;

/*!
 * Converts `expires` options of index objects to `expiresAfterSeconds` options for MongoDB.
 *
 * @param {Object} object
 * @api private
 */

exports.expires = function expires (object) {
  if (!(object && 'Object' == object.constructor.name)) return;
  if (!('expires' in object)) return;

  var when;
  if ('string' != typeof object.expires) {
    when = object.expires;
  } else {
    when = Math.round(ms(object.expires) / 1000);
  }
  object.expireAfterSeconds = when;
  delete object.expires;
}

/*!
 * Converts arguments to ReadPrefs the driver
 * can understand.
 *
 * @TODO move this into the driver layer
 * @param {String|Array} pref
 * @param {Array} [tags]
 */

exports.readPref = function readPref (pref, tags) {
  if (Array.isArray(pref)) {
    tags = pref[1];
    pref = pref[0];
  }

  switch (pref) {
    case 'p':
      pref = 'primary';
      break;
    case 'pp':
      pref = 'primaryPreferred';
      break;
    case 's':
      pref = 'secondary';
      break;
    case 'sp':
      pref = 'secondaryPreferred';
      break;
    case 'n':
      pref = 'nearest';
      break;
  }

  return new ReadPref(pref, tags);
}

/*!
 * Populate options constructor
 */

function PopulateOptions (path, select, match, options, model) {
  this.path = path;
  this.match = match;
  this.select = select;
  this.options = options;
  this.model = model;
  this._docs = {};
}

// make it compatible with utils.clone
PopulateOptions.prototype.constructor = Object;

// expose
exports.PopulateOptions = PopulateOptions;

/*!
 * populate helper
 */

exports.populate = function populate (path, select, model, match, options) {
  // The order of select/conditions args is opposite Model.find but
  // necessary to keep backward compatibility (select could be
  // an array, string, or object literal).

  // might have passed an object specifying all arguments
  if (1 === arguments.length) {
    if (path instanceof PopulateOptions) {
      return [path];
    }

    if (Array.isArray(path)) {
      return path.map(function(o){
        return exports.populate(o)[0];
      });
    }

    if (exports.isObject(path)) {
      match = path.match;
      options = path.options;
      select = path.select;
      model = path.model;
      path = path.path;
    }
  } else if ('string' !== typeof model) {
    options = match;
    match = model;
    model = undefined;
  }

  if ('string' != typeof path) {
    throw new TypeError('utils.populate: invalid path. Expected string. Got typeof `' + typeof path + '`');
  }

  var ret = [];
  var paths = path.split(' ');
  for (var i = 0; i < paths.length; ++i) {
    ret.push(new PopulateOptions(paths[i], select, match, options, model));
  }

  return ret;
}

/*!
 * Return the value of `obj` at the given `path`.
 *
 * @param {String} path
 * @param {Object} obj
 */

exports.getValue = function (path, obj, map) {
  return mpath.get(path, obj, '_doc', map);
}

/*!
 * Sets the value of `obj` at the given `path`.
 *
 * @param {String} path
 * @param {Anything} val
 * @param {Object} obj
 */

exports.setValue = function (path, val, obj, map) {
  mpath.set(path, val, obj, '_doc', map);
}

/*!
 * Returns an array of values from object `o`.
 *
 * @param {Object} o
 * @return {Array}
 * @private
 */

exports.object = {};
exports.object.vals = function vals (o) {
  var keys = Object.keys(o)
    , i = keys.length
    , ret = [];

  while (i--) {
    ret.push(o[keys[i]]);
  }

  return ret;
}

/*!
 * @see exports.options
 */

exports.object.shallowCopy = exports.options;

/*!
 * Safer helper for hasOwnProperty checks
 *
 * @param {Object} obj
 * @param {String} prop
 */

exports.object.hasOwnProperty = function (obj, prop) {
  return Object.prototype.hasOwnProperty.call(obj, prop);
}

/*!
 * Determine if `val` is null or undefined
 *
 * @return {Boolean}
 */

exports.isNullOrUndefined = function (val) {
  return null == val
}

/*!
 * ignore
 */

exports.array = {};

/*!
 * Flattens an array.
 *
 * [ 1, [ 2, 3, [4] ]] -> [1,2,3,4]
 *
 * @param {Array} arr
 * @param {Function} [filter] If passed, will be invoked with each item in the array. If `filter` returns a falsey value, the item will not be included in the results.
 * @return {Array}
 * @private
 */

exports.array.flatten = function flatten (arr, filter, ret) {
  ret || (ret = []);

  arr.forEach(function (item) {
    if (Array.isArray(item)) {
      flatten(item, filter, ret);
    } else {
      if (!filter || filter(item)) {
        ret.push(item);
      }
    }
  });

  return ret;
}