Source: token.js

/**
 * A token wraps a string representation of a token
 * as it is passed through the text processing pipeline.
 *
 * @constructor
 * @param {string} [str=''] - The string token being wrapped.
 * @param {object} [metadata={}] - Metadata associated with this token.
 */
lunr.Token = function (str, metadata) {
  this.str = str || ""
  this.metadata = metadata || {}
}

/**
 * Returns the token string that is being wrapped by this object.
 *
 * @returns {string}
 */
lunr.Token.prototype.toString = function () {
  return this.str
}

/**
 * A token update function is used when updating or optionally
 * when cloning a token.
 *
 * @callback lunr.Token~updateFunction
 * @param {string} str - The string representation of the token.
 * @param {Object} metadata - All metadata associated with this token.
 */

/**
 * Applies the given function to the wrapped string token.
 *
 * @example
 * token.update(function (str, metadata) {
 *   return str.toUpperCase()
 * })
 *
 * @param {lunr.Token~updateFunction} fn - A function to apply to the token string.
 * @returns {lunr.Token}
 */
lunr.Token.prototype.update = function (fn) {
  this.str = fn(this.str, this.metadata)
  return this
}

/**
 * Creates a clone of this token. Optionally a function can be
 * applied to the cloned token.
 *
 * @param {lunr.Token~updateFunction} [fn] - An optional function to apply to the cloned token.
 * @returns {lunr.Token}
 */
lunr.Token.prototype.clone = function (fn) {
  fn = fn || function (s) { return s }
  return new lunr.Token (fn(this.str, this.metadata), this.metadata)
}