Source: utils.js

/*!
 * lunr.utils
 * Copyright (C) @YEAR Oliver Nightingale
 */

/**
 * A namespace containing utils for the rest of the lunr library
 * @namespace lunr.utils
 */
lunr.utils = {}

/**
 * Print a warning message to the console.
 *
 * @param {String} message The message to be printed.
 * @memberOf lunr.utils
 * @function
 */
lunr.utils.warn = (function (global) {
  /* eslint-disable no-console */
  return function (message) {
    if (global.console && console.warn) {
      console.warn(message)
    }
  }
  /* eslint-enable no-console */
})(this)

/**
 * Convert an object to a string.
 *
 * In the case of `null` and `undefined` the function returns
 * the empty string, in all other cases the result of calling
 * `toString` on the passed object is returned.
 *
 * @param {Any} obj The object to convert to a string.
 * @return {String} string representation of the passed object.
 * @memberOf lunr.utils
 */
lunr.utils.asString = function (obj) {
  if (obj === void 0 || obj === null) {
    return ""
  } else {
    return obj.toString()
  }
}

/**
 * Clones an object.
 *
 * Will create a copy of an existing object such that any mutations
 * on the copy cannot affect the original.
 *
 * Only shallow objects are supported, passing a nested object to this
 * function will cause a TypeError.
 *
 * Objects with primitives, and arrays of primitives are supported.
 *
 * @param {Object} obj The object to clone.
 * @return {Object} a clone of the passed object.
 * @throws {TypeError} when a nested object is passed.
 * @memberOf Utils
 */
lunr.utils.clone = function (obj) {
  if (obj === null || obj === undefined) {
    return obj
  }

  var clone = Object.create(null),
      keys = Object.keys(obj)

  for (var i = 0; i < keys.length; i++) {
    var key = keys[i],
        val = obj[key]

    if (Array.isArray(val)) {
      clone[key] = val.slice()
      continue
    }

    if (typeof val === 'string' ||
        typeof val === 'number' ||
        typeof val === 'boolean') {
      clone[key] = val
      continue
    }

    throw new TypeError("clone is not deep and does not support nested objects")
  }

  return clone
}