Source: tokenizer.js

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

/**
 * A function for splitting a string into tokens ready to be inserted into
 * the search index. Uses `lunr.tokenizer.separator` to split strings, change
 * the value of this property to change how strings are split into tokens.
 *
 * This tokenizer will convert its parameter to a string by calling `toString` and
 * then will split this string on the character in `lunr.tokenizer.separator`.
 * Arrays will have their elements converted to strings and wrapped in a lunr.Token.
 *
 * Optional metadata can be passed to the tokenizer, this metadata will be cloned and
 * added as metadata to every token that is created from the object to be tokenized.
 *
 * @static
 * @param {?(string|object|object[])} obj - The object to convert into tokens
 * @param {?object} metadata - Optional metadata to associate with every token
 * @returns {lunr.Token[]}
 * @see {@link lunr.Pipeline}
 */
lunr.tokenizer = function (obj, metadata) {
  if (obj == null || obj == undefined) {
    return []
  }

  if (Array.isArray(obj)) {
    return obj.map(function (t) {
      return new lunr.Token(
        lunr.utils.asString(t).toLowerCase(),
        lunr.utils.clone(metadata)
      )
    })
  }

  var str = obj.toString().trim().toLowerCase(),
      len = str.length,
      tokens = []

  for (var sliceEnd = 0, sliceStart = 0; sliceEnd <= len; sliceEnd++) {
    var char = str.charAt(sliceEnd),
        sliceLength = sliceEnd - sliceStart

    if ((char.match(lunr.tokenizer.separator) || sliceEnd == len)) {

      if (sliceLength > 0) {
        var tokenMetadata = lunr.utils.clone(metadata) || {}
        tokenMetadata["position"] = [sliceStart, sliceLength]
        tokenMetadata["index"] = tokens.length

        tokens.push(
          new lunr.Token (
            str.slice(sliceStart, sliceEnd),
            tokenMetadata
          )
        )
      }

      sliceStart = sliceEnd + 1
    }

  }

  return tokens
}

/**
 * The separator used to split a string into tokens. Override this property to change the behaviour of
 * `lunr.tokenizer` behaviour when tokenizing strings. By default this splits on whitespace and hyphens.
 *
 * @static
 * @see lunr.tokenizer
 */
lunr.tokenizer.separator = /[\s\-]+/