lodash-compat/internal/initCloneByTag.js

The compatibility build of lodash modular utilities.

var bufferClone = require('./bufferClone');

/** `Object#toString` result references. */
var boolTag = '[object Boolean]',
    dateTag = '[object Date]',
    numberTag = '[object Number]',
    regexpTag = '[object RegExp]',
    stringTag = '[object String]';

var arrayBufferTag = '[object ArrayBuffer]',
    float32Tag = '[object Float32Array]',
    float64Tag = '[object Float64Array]',
    int8Tag = '[object Int8Array]',
    int16Tag = '[object Int16Array]',
    int32Tag = '[object Int32Array]',
    uint8Tag = '[object Uint8Array]',
    uint8ClampedTag = '[object Uint8ClampedArray]',
    uint16Tag = '[object Uint16Array]',
    uint32Tag = '[object Uint32Array]';

/** Used to match `RegExp` flags from their coerced string values. */
var reFlags = /\w*$/;

/** Native method references. */
var Uint8Array = global.Uint8Array;

/** Used to lookup a type array constructors by `toStringTag`. */
var ctorByTag = {};
ctorByTag[float32Tag] = global.Float32Array;
ctorByTag[float64Tag] = global.Float64Array;
ctorByTag[int8Tag] = global.Int8Array;
ctorByTag[int16Tag] = global.Int16Array;
ctorByTag[int32Tag] = global.Int32Array;
ctorByTag[uint8Tag] = Uint8Array;
ctorByTag[uint8ClampedTag] = global.Uint8ClampedArray;
ctorByTag[uint16Tag] = global.Uint16Array;
ctorByTag[uint32Tag] = global.Uint32Array;

/**
 * Initializes an object clone based on its `toStringTag`.
 *
 * **Note:** This function only supports cloning values with tags of
 * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`.
 *
 * @private
 * @param {Object} object The object to clone.
 * @param {string} tag The `toStringTag` of the object to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @returns {Object} Returns the initialized clone.
 */
function initCloneByTag(object, tag, isDeep) {
  var Ctor = object.constructor;
  switch (tag) {
    case arrayBufferTag:
      return bufferClone(object);

    case boolTag:
    case dateTag:
      return new Ctor(+object);

    case float32Tag: case float64Tag:
    case int8Tag: case int16Tag: case int32Tag:
    case uint8Tag: case uint8ClampedTag: case uint16Tag: case uint32Tag:
      // Safari 5 mobile incorrectly has `Object` as the constructor of typed arrays.
      if (Ctor instanceof Ctor) {
        Ctor = ctorByTag[tag];
      }
      var buffer = object.buffer;
      return new Ctor(isDeep ? bufferClone(buffer) : buffer, object.byteOffset, object.length);

    case numberTag:
    case stringTag:
      return new Ctor(object);

    case regexpTag:
      var result = new Ctor(object.source, reFlags.exec(object));
      result.lastIndex = object.lastIndex;
  }
  return result;
}

module.exports = initCloneByTag;