TW Blog :: Archives for August 2004

Simple Acronym Handler

Relates to PHP and Web Standards

Many code snippets for handling acronyms seem to rely on <a href="http://www.php.net/preg_replace" title="PHP Doc for preg_replace">preg_replace()</a>. The problem with this method is ensuring that double replacements do not occur (e.g. with XHTML and HTML). A much better function to use is <a href="http://www.php.net/strtr" title="PHP Doc for strtr">strtr()</a> with two arguments:

$translation_array = array(
  'XHTML' => '<acronym title="eXtensible Hypertext Markup Language">',
  'HTML'  => '<acronym title="Hypertext Markup Language">'
                           );
$str = strtr($str, $translation_array);

It will always look for the longest pattern first and will not try to replace stuff it has already worked on. It is also really quick.

I have been test running the following function on this site to automate acronym handling:

function ss_fns_parse_acronyms($copy) {
  
  static $trans = array();
  
  if (empty($trans)) {
    $dat_file = SOME_PATH . '/data/acronyms.dat';
    $acronyms = parse_ini_file($dat_file);
    foreach($acronyms as $a => $d) {
      $trans[$a] = "<acronym title=\"$d\">$a</acronym>";  
    }    
  }
  
  return strtr($copy, $trans);        
}

The acronyms can be stored in php_ini format in a file, thus new acronyms can be added without interfering with this code. There are occassional limitations and gotchas - e.g. OS inadvertantly appearing in $_POST, but it is an efficient and clean alternative to preg_replace.

Posted on Friday, Aug 13, 2004 at 04:58:50.