function truncate_utf8

Truncates a UTF-8-encoded string safely to a number of characters.

Parameters

$string: The string to truncate.

$max_length: An upper limit on the returned string length, including trailing ellipsis if $add_ellipsis is TRUE.

$wordsafe: If TRUE, attempt to truncate on a word boundary. Word boundaries are spaces, punctuation, and Unicode characters used as word boundaries in non-Latin languages; see PREG_CLASS_UNICODE_WORD_BOUNDARY for more information. If a word boundary cannot be found that would make the length of the returned string fall within length guidelines (see parameters $max_length and $min_wordsafe_length), word boundaries are ignored.

$add_ellipsis: If TRUE, add t('...') to the end of the truncated string (defaults to FALSE). The string length will still fall within $max_length.

$min_wordsafe_length: If $wordsafe is TRUE, the minimum acceptable length for truncation (before adding an ellipsis, if $add_ellipsis is TRUE). Has no effect if $wordsafe is FALSE. This can be used to prevent having a very short resulting string that will not be understandable. For instance, if you are truncating the string "See myverylongurlexample.com for more information" to a word-safe return length of 20, the only available word boundary within 20 characters is after the word "See", which wouldn't leave a very informative string. If you had set $min_wordsafe_length to 10, though, the function would realise that "See" alone is too short, and would then just truncate ignoring word boundaries, giving you "See myverylongurl..." (assuming you had set $add_ellipses to TRUE).

Return value

string: The truncated string.

File

core/includes/unicode.inc, line 317

Provides Unicode-related conversions and operations.

Code

function truncate_utf8($string, $max_length, $wordsafe = FALSE, $add_ellipsis = FALSE, $min_wordsafe_length = 1) {
  $ellipsis = '';
  $max_length = max($max_length, 0);
  $min_wordsafe_length = max($min_wordsafe_length, 0);

  if (backdrop_strlen($string) <= $max_length) {
    // No truncation needed, so don't add ellipsis, just return.
    return $string;
  }

  if ($add_ellipsis) {
    // Truncate ellipsis in case $max_length is small. The ellipsis character is
    // wrapped in t(), since different characters or symbols may be used for
    // this purpose in other languages.
    $ellipsis = backdrop_substr(t('…'), 0, $max_length);
    $max_length -= backdrop_strlen($ellipsis);
    $max_length = max($max_length, 0);
  }

  if ($max_length <= $min_wordsafe_length) {
    // Do not attempt word-safe if lengths are bad.
    $wordsafe = FALSE;
  }

  if ($wordsafe) {
    $matches = array();
    // Find the last word boundary, if there is one within $min_wordsafe_length
    // to $max_length characters. preg_match() is always greedy, so it will
    // find the longest string possible.
    $found = preg_match('/^(.{' . $min_wordsafe_length . ',' . $max_length . '})[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . ']/u', $string, $matches);
    if ($found) {
      $string = $matches[1];
    }
    else {
      $string = backdrop_substr($string, 0, $max_length);
    }
  }
  else {
    $string = backdrop_substr($string, 0, $max_length);
  }

  if ($add_ellipsis) {
    // If we're adding an ellipsis, remove any trailing periods.
    $string = rtrim($string, '.');

    $string .= $ellipsis;
  }

  return $string;
}