MediaWiki BreadCrumbs

From Luke Jackson

Summary

This is an extension to the MediaWiki that creates "BreadCrumbs" of the links you visit within the MediaWiki.

I can't recall where I found this extension and a Google search did not locate the owner. I am posting it as an Unknown work. If you are the owner please contact me and I will give you credit. :)

Installation

1. Copy the contents of kwBreadCrumbs.php into a file called kwBreadCrumbs.php and upload it to your extensions folder.
2. Test

kwBreadCrumbs.php

<?php

$wgExtensionFunctions[] = "kwBreadCrumbsExtension";
 
// ------------------------------------------------------------------------ 
function kwBreadCrumbsExtension() 
{
  global $wgParser;
  $wgParser->setHook( "kw_bread_crumbs", "kwBreadCrumbs");
}
 
// ------------------------------------------------------------------------ 
function kwBreadCrumbs($input) 
{
  global $wgUser, $wgTitle, $wgOut;

  kwBreadCrumbsNoCache();

  // Initialize parameters

  $max_nb_crumbs = 5;
  $max_title_len = 30;
  $label = 'BreadCrumbs: ';
  $separator = ' : ';
  $trim_prefixes = array();
  $prefix = NULL;
  $on_top_hack = 0;
  $class = 'kwBreadCrumbs';
  $id = 'kwBreadCrumbs';
  $session_key = NULL;

  // Parse each parameter

  $params = explode('|', $input);
  foreach ($params as $param) 
    {
    $param_components = explode("=", $param, 2);
    $param_name = strtolower(trim($param_components[0]));
    $param_value = isset($param_components[1]) ? $param_components[1] : NULL;

    // max_nb_crumbs

    if ($param_name == 'max_nb_crumbs')
      {
      if (!strlen($param_value))
        {
        return kwBreadCrumbsError("missing value for parameter '$param_name'");
        }
      $value = (int)$param_value;
      if ($value >= 1 && $value <= 50)
        {
        $max_nb_crumbs = $value;
        }
      }

    // max_title_len

    else if ($param_name == 'max_title_len')
      {
      if (!strlen($param_value))
        {
        return kwBreadCrumbsError("missing value for parameter '$param_name'");
        }
      $value = (int)$param_value;
      if ($value >= 0 && $value <= 150)
        {
        $max_title_len = $value;
        }
      }

    // trim_prefix

    else if ($param_name == 'trim_prefix')
      {
      if (!strlen($param_value))
        {
        return kwSiteMapError("missing value for parameter '$param_name'");
        }
      $trim_prefixes[] = $param_value;
      }

    // prefix

    else if ($param_name == 'prefix')
      {
      if (!strlen($param_value))
        {
        return kwSiteMapError("missing value for parameter '$param_name'");
        }
      $prefix = $param_value;
      }

    // separator

    else if ($param_name == 'separator')
      {
      if (!strlen($param_value))
        {
        return kwBreadCrumbsError("missing value for parameter '$param_name'");
        }
      $separator = $param_value;
      }

    // on_top_hack

    else if ($param_name == 'on_top_hack')
      {
      if (!strlen($param_value))
        {
        return kwBreadCrumbsError("missing value for parameter '$param_name'");
        }
      $on_top_hack = $param_value ? 1 : 0;;
      }

    // session_key

    else if ($param_name == 'session_key')
      {
      if (!strlen($param_value))
        {
        return kwSiteMapError("missing value for parameter '$param_name'");
        }
      $session_key = $param_value;
      }

    // unknown parameter

    else if ($param_name)
      {
      return kwBreadCrumbsError("unknown parameter '$param_name'");
      }
    }

  // Make sure we started a session

  @session_start();

  global $wgSitename, $wgVersion;
  if (is_null($session_key))
    {
    $session_key = "kw_bread_crumbs: $wgSitename ($wgVersion)";
    }
  if (!isset($_SESSION[$session_key])) 
    { 
    $_SESSION[$session_key] = array(); 
    }

  // Remove duplicates

  $current_title = $wgTitle->getPrefixedText();

  $titles = array();
  foreach ($_SESSION[$session_key] as $title)
    {
    if ($title != $current_title)
      {
      $titles[] = $title;
      }
    }
  $_SESSION[$session_key] = $titles;
  $_SESSION[$session_key][] = $current_title;

  // Shrink the list

  $nb_titles = count($_SESSION[$session_key]);
  while ($nb_titles > $max_nb_crumbs)
    {
    array_shift($_SESSION[$session_key]);
    $nb_titles--;
    }

  // Create the trace

  $skin =& $wgUser->getSkin();

  $urls = array();
  foreach ($_SESSION[$session_key] as $title)
    {
    $text = $title;
    if (count($trim_prefixes))
      {
      foreach ($trim_prefixes as $trim_prefix)
        {
        if (strpos($text, $trim_prefix) === 0)
          {
          $text = substr($text, strlen($trim_prefix));
          }
        }
      }
    if ($max_title_len > 0)
      {
      $text_len = strlen($text);
      if ($text_len > $max_title_len)
        {
        $half = (int)($max_title_len / 2);
        $text = substr($text, 0, $max_title_len - $half - 1) . 'â¦' . 
           substr($text, -$half);
        }
      }
    $urls[] = 
       ($title == $current_title ? $text : $skin->makeLink($title, $text));
    }

  $output = '<div id="' . $id . '" class="' . $class . '"';
  $output .= '>'.$label;

  $output .= 
     htmlentities(html_entity_decode($prefix)) . 
     implode(htmlentities(html_entity_decode($separator)), $urls);

  $output .= '</div>';

  // Hack to display the titles on top:
  // - only for version 1.3
  // - only if monobook
  // - piggy-back after the site notice (wgSiteNotice)
  // - remove border if <= 1.3.0 beta, alpha, etc.

  if ($on_top_hack)
    {
    if (preg_match("/^(\d+)\.(\d+)\.(\d+)(\w*)$/", $wgVersion, $ver))
      {
      if ($ver[1] == 1 && $ver[2] == 3)
        {
        $user_skin_name = $wgUser->getOption('skin');
        if ($user_skin_name == "monobook")
          {
          global $wgSiteNotice;
          if (!$wgSiteNotice || !strpos($wgSiteNotice, $class))
            {
            $new_notice = NULL;
            if ($ver[3] == 0 && isset($ver[4]))
              {
              $new_notice .= '<div style="margin: -1px -1px -1px -1px; border: 1px solid #FFFFFF; font-weight: bold;"></div>';
              }
            $new_notice .= '</div>' . $output;
            if ($wgSiteNotice)
              {
              $new_notice .= '<div id="siteNotice">' . $wgSiteNotice;
              }
            else
              {
              $new_notice .= '<div>';
              }
            $wgSiteNotice = $new_notice;
            }
          }
        }
      }
    return '';
    }

  return $output;
}

// ------------------------------------------------------------------------ 
function kwBreadCrumbsError($msg) 
{
  return "[kw_bread_crumbs] <b>Error</b>: " . htmlspecialchars($msg);
}

// ------------------------------------------------------------------------ 
function kwBreadCrumbsNoCache() 
{
  global $wgTitle, $wgOut;
  if (!isset($wgTitle) || !isset($wgOut))
    {
    return;
    }

  /*
    Let's 'touch' the page to invalidate its cache.
    The code below is slightly identical to Title::invalidateCache().
    Even though invalidateCache() sets cur_touched to 'now', we are still
    in the process of creating and rendering the page itself and the 
    page will be cached only once it is done. At the end of the day the
    cache would always end up newer than cur_touched, defeating the whole
    purpose of calling invalidateCache().
    The trick here is to set cur_touched in the future, something not too
    intrusive, say 'now' + 120 seconds, provided that we expect the cached
    page to be created within 120 secs after this extension code has been
    executed. That way, cur_touched remains 'fresher' than the cache, and
    the page is always re-created dynamically.
  */

  $ts = mktime();
  $now = gmdate("YmdHis", $ts + 120);
  $ns = $wgTitle->getNamespace();
  $ti = wfStrencode($wgTitle->getDBkey());
  $sql = "UPDATE page SET page_touched='$now' WHERE page_namespace=$ns AND page_title='$ti'";
  wfQuery($sql, DB_WRITE, "kwBreadCrumbsNoCache");

  // This does not seem to do anything. I assume once it's called here
  // in the extension, it's already too late.

  $wgOut->enableClientCache(false);

  // The followings should prevent browsers to cache too long

  /*
  $wgOut->addMeta("http:Pragma", "no-cache");
  $wgOut->addMeta("http:no-cache", NULL);
  $wgOut->addMeta("http:EXPIRES", "TUES, 31 DEC 1996 12:00:00 GMT");
  */

  // HTTP_IF_MODIFIED_SINCE ? // see OutputPage: checkLastModified
}

// ------------------------------------------------------------------------ 
function kwBreadCrumbsTAL() 
{
  global $wgKwBreadCrumbs;
  return kwBreadCrumbs(is_null($wgKwBreadCrumbs) ? '' : $wgKwBreadCrumbs);
}

?>