@function __trimmed-left-index($string) {
  $index: 1;
  $length: str-length($string);

  @while ($index <= $length) and (__is-space(__char-at($string, $index))) {
    $index: $index + 1;
  }

  @return $index;
}

@function __trimmed-right-index($string) {
  $index: str-length($string);

  @while ($index > 0) and (__is-space(__char-at($string, $index))) {
    $index: $index - 1;
  }

  @return $index;
}

@function __trim($string, $chars: null, $guard: null) {
  $value: $string;
  $string: __base-to-string($string);

  @if not($string) or ($string == "") or ($chars == "") {
    @return $string;
  }

  @if (
    if($guard, __is-iteratee-call($value, $chars, $guard), ($chars == null))
  ) {
    @return str-slice(
      $string,
      __trimmed-left-index($string),
      __trimmed-right-index($string)
    );
  }

  $chars: __base-to-string($chars);

  @return str-slice(
    $string,
    __chars-left-index($string, $chars),
    __chars-right-index($string, $chars)
  );
}

@function __trim-left($string, $chars: null, $guard: null) {
  $value: $string;
  $string: __base-to-string($string);

  @if not($string) or ($string == "") or ($chars == "") {
    @return $string;
  }

  @if (
    if($guard, __is-iteratee-call($value, $chars, $guard), ($chars == null))
  ) {
    @return str-slice($string, __trimmed-left-index($string));
  }

  $chars: __base-to-string($chars);

  @return str-slice($string, __chars-left-index($string, $chars));
}

@function __trim-right($string, $chars: null, $guard: null) {
  $value: $string;
  $string: __base-to-string($string);

  @if not($string) or ($string == "") or ($chars == "") {
    @return $string;
  }

  @if (
    if($guard, __is-iteratee-call($value, $chars, $guard), ($chars == null))
  ) {
    @return str-slice($string, 0, __trimmed-right-index($string));
  }

  $chars: __base-to-string($chars);

  @return str-slice($string, 0, __chars-right-index($string, $chars));
}

/// Removes leading and trailing whitespace or specified characters from `$string`.
///
///
/// @access public
/// @group String
/// @param {string} $string [''] - The string to trim.
/// @param {string} $chars [' '] - The characters to trim.
/// @returns {string} Returns the trimmed string.
/// @example scss
/// $foo: _trim('  abc  ');
/// // => 'abc'
/// $foo: _trim('-_-abc-_-', '_-');
/// // => 'abc'
/// $foo: _map(('  foo  ', '  bar  '), _trim);
/// // => ('foo', 'bar')

@function _trim($args...) {
  @return call(get-function("__trim"), $args...);
}

/// Removes leading whitespace or specified characters from `$string`.
///
///
/// @access public
/// @group String
/// @param {string} $string [''] - The string to trim.
/// @param {string} $chars [whitespace] - The characters to trim.
/// @returns {string} Returns the trimmed string.
/// @example scss
/// /// _trim-left('  abc  ');
/// // => 'abc  '
/// /// _trim-left('-_-abc-_-', '_-');
/// // => 'abc-_-'

@function _trim-left($args...) {
  @return call(get-function("__trim-left"), $args...);
}

/// Removes trailing whitespace or specified characters from `$string`.
///
///
/// @access public
/// @group String
/// @param {string} $string [''] - The string to trim.
/// @param {string} $chars [' '] - The characters to trim.
/// @returns {string} Returns the trimmed string.
/// @example scss
/// $foo: _trim-right('  abc  ');
/// // => '  abc'
/// $foo: _trim-right('-_-abc-_-', '_-');
/// // => '-_-abc'

@function _trim-right($args...) {
  @return call(get-function("__trim-right"), $args...);
}