=====Simple History trail for wikka=====

The following code is a simple history trails feature (JavaWoman informed me that "breadcrumbs" are strictly for heirarchical systems & since wiki's are "flat" calling it a "breadcrumb" feature is inappropriate) that can be added to the header.php code to provide a linear history of the last few previously visited pages in the wiki. It only requires a single field added to the users database (add a field called "recentpages" set as type TINYTEXT and set it so it can be null (which is the default)) and it seems to work like a charm. I was inspired by the trail feature at coocoo wakka, but wrote this from scratch. 

add the following code to your ##header.php## file near the bottom (immediately before the last "?>"). 
%%(php)
// WikiTrails code V1.1a copyright by G. M. Bowen & Andrew Somerville, 2005. 
// Version1.1a has a minor code change (as suggested here) so that non-wikiname pages were linked properly
// Prepared for a SSHRC funded research project. Licensed under GPL.
// Please keep attributions if distributing code.  
if ($user = $this->GetUser())
 
	if (str_word_count($newstring) > 6) {			
			$newstring = trim(strstr($newstring, " "));
	} 	
	$newstring .= " ";
	
	$this->query("UPDATE ".$this->config['table_prefix']."users SET recentpages = '$newstring' WHERE name='$username' ");	

	// Add trails to printout
	$recent = $this->LoadSingle("SELECT recentpages FROM ".$this->config["table_prefix"]."users WHERE name='".$username."'");

	######
	# Section rewritten by andrew. 
	$page_names = Array();
	
	# Parse string at spaces, into an array. 
	$this_pagename = strtok(trim($recent[recentpages]), " ");
	while ($this_pagename) {
		array_push($page_names,$this_pagename); 
		$this_pagename = strtok(" ");
	}
	
	# Get rid of duplicates. 
	$page_names = array_unique($page_names);
	
	# Create the trail by walking through the array of page names.
	$separator  = ""; 
	$page_trail = "";
	foreach ($page_names as $this_pagename) {
		$page_trail .= $separator."[[".$this_pagename."]]";
		$separator   = "-->";
	}
	
	# Print the trail. 
	echo "<br /><small><b>Trail:</b> ".$this->format($page_trail)."</small>";
	#######
}
//FINISH breadcrumb code%%

If you want the list of previously visited pages to be greater or lesser change the "6" value. 

Hope this meets your needs folks. If you find ways of making the code more efficient (and that is certainly possible), then please feel free to update it. 

Version V1.1 fixes search and replace issues. Problem was that if you were at the page ""AndrEw"" and you also had a page ""AndrewsPage"" then when you moved around sooner or later you'd get ""sPage"". That problem is now solved.
----
Added by RolandStens
I have created a version that uses the $_SESSION variable, this makes it a bit more usable since it is not dependent on a user being logged in or not.
My persistance in calling this bread crumbs is hopefully no cause for major discussion. I hope people find this useful.

~& Updated the code so now it behaves a bit better and incorporates Ian's comment below.
~& You can see this in operation [[http://stens.ca/kb | here]] RolandStens

%%(php)
<?php
// WikiTrails code V2.1 based on copyrighted code by G. M. Bowen & Andrew Somerville, 2005.
// Version 2 stores the crumbs in the $_SESSION variable. This makes this feature usable for all users.
// Originally Prepared for a SSHRC funded research project extended by Roland Stens, 2006. Licensed under GPL.
// Please keep attributions if distributing code.  

	# Define the maximum breadcrumbs shown.
	define("MAX_CRUMBS", 5);
	$crumbs=Array();
	
	# Just get the PageTage, no use in doing that more times than 1
	$PageTag=$this->GetPageTag();
	
	# Find out if the breadcrumbs were already stored.
	if (!isset($_SESSION['breadcrumbs'])) {
	   # Not stored yet, so set the current page name in the crumbs array.
	   $crumbs[0]=$PageTag;
	} else {
	   # The crumbs are already stored, so get them and put them in the crumbs array.
	   $crumbs=$_SESSION['breadcrumbs'];
	   
	   # Test for the maximum amount of crumbs and if the last pagetag is not
	   # the same as the last stored tag. If it is a duplicate we'll get rid of it later.
	   if (count($crumbs) >= MAX_CRUMBS and $PageTag != $crumbs[MAX_CRUMBS - 1])
	   {
	   	# Drop the first element in the crumbs array.
	   	array_shift($crumbs);
	   	# Add the new page name to the last position in the array.
	   	$crumbs[MAX_CRUMBS - 1]= $PageTag;
	   }
	   else
	   {
	   	# Not at the maximum yet, then just add to page to the end of the array.
	   	$crumbs[count($crumbs)]= $PageTag;
	   }	
	}
	
	# Get rid of duplicates, but only if they are in subsequent array locations. 
	$count=1;
	$temp = Array();
	$target= Array();
	# Only do this, if you have 3 or more entries in the array
	if (count($crumbs) > 2) {
		while ($count <= (count($crumbs) - 1))
		{
			$temp[$count - 1] = $crumbs[$count - 1];
			$temp[$count] = $crumbs[$count];
			$temp = array_unique($temp);
			$target= $target + $temp;
			$temp = "";
			$count++;
		}
		$crumbs = $target;
	}
	else {
		$crumbs = array_unique($crumbs);
	}		
	
	
	# Save the breadcrumbs.
	$_SESSION['breadcrumbs'] = $crumbs;
	
	# Create the trail by walking through the array of page names.
	$separator  = ""; 
	$page_trail = "";
	foreach ($crumbs as $this_crumb) {
		$page_trail .= $separator."[[".$this_crumb."]]";
		$separator   = "-->";
	}
	
	# Print the trail.
	echo "<b>Trail: </b>".$this->format($page_trail)."<hr /><br />";
	#######

//FINISH breadcrumb code
?>
%%

~& After implementing this one of my installations I felt that populating this with four copies of the same page when editing was less useful.  I made a modification to only add the new page if it was different from the previous one, 
~& after the line:- ## $crumbs=$_SESSION['breadcrumbs'];##
~& add %%(php)
			#only add breadcrumb if new page is different
		if ($crumbs[count($crumbs)-1] != $this->GetPageTag() ) {
		#to enclose the if / else clause following it 
		}
		%%
~& 
~& which feels  psychological correct (if not strictly accurate) //IanHayhurst//


----
CategoryUserContributions