[Chameleon-dev] [Bug 502] [Chameleon] Recursive preprocessing enhancement

[bugzilla-daemon at www.maptools.org]

http://www.maptools.org/bugzilla/show_bug.cgi?id=502





------- Additional Comments From jlacroix at dmsolutions.ca  2004-07-07 13:58 -------
Suggestion from Paul:

Julien, sorry, I didn't really follow this thread too closely so I am not
entirely sure what the patch does ...  here is my interpretation:

1. process [$$] replacements  << added by pxniw
2. process [##] includes
3. process [$$] replacements

if this is right, then I have some comments ...

* if we are allowing multiple passes, should we run the include process twice
(i.e. pages included using [##] could include [##] inside them?

* simply adding more steps isn't going to solve the recursive cases ...

* there is a lot of code duplication

I suggest a more robust implementation that takes the code and divides it into
two functions

/**
 * Replace text in target by searching for blocks delimited by the start
 * and end delimiters.  The caller provides a method that takes a text
 * string and returns the value to be inserted in place of the tag, or
 * false if no tag replacement is possible.  This method returns the
 * number of replacements that actually happened.
 *
 * A note on fReplacement.  It can be a string (name of function to
 * call) or an array.  If it is an array, it must contain 2 elements,
 * the first element is the name of the function to call.  The second
 * element is either the name of a class, in which case the function
 * is called as a static method of the class using call_user_func, or
 * it is an object and is called using call_user_method.
 *
 * @param fReplacer a function that returns the text to be inserted
 * @param szText  the text to be scanned for replacements
 * @param szStart a text string that defines the start of a replacement
 *        block
 * @param szEnd a text string that defines the end of a replacement
 *        block
 * @return the number of replacements that happened.
 */
ProcessReplacements( $fReplacement, $szText, $szStart = "[$", $szEnd = "$]" )
{
  $nReplacements = 0;
  ... search for start and end tags, assign to $szKey ... in loop
  //start loop
  {
    if (is_array($fReplacement) &&
        isset($fReplacement[1]))
    {
        if (is_object($fReplacement[1]))
        {
        //use call_user_method
            $szReplacement = call_user_method($fReplacement[0],
                             $fReplacement[1],
                             $szKey );
        }
        else
        {
            //use call_user_func, assume that array is in
            $szReplacement = call_user_func( $fReplacement, $szKey );
     }
     else
     {
       //this would be an error
     }
   }
   else
   {
        //use call_user_func, assume that array is in
        $szReplacement = call_user_func( $fReplacement, $szKey );
   }
   if ($szReplacment !=== false)
   {
       //process replacement now
       $nReplacements ++;
   }
   else
   {
      //leave text alone, no replacement to happen.
   }
  //end loop
  return $nReplacements;
}


Then in the TemplateParser code, we would use something like the following block

$nReplacements = 1;  //just to get us into the loop
$nLevel = 10;
while ($nReplacements > 0 && $nLevel > 0)
{
  $nReplacements = 0;
  $nReplacements = $this->ProcessReplacements(
          array( "GetReplacement", $this ), $this->mszTemplate );
          "[$", "$]" );
  $nReplacements += $this->ProcessReplacements(
          array( "GetInclude", $this ), $this->mszTemplate,
          "[#", "#]" );
  $nLevel ++;
}

And we would add the following methods to the TemplateParser

/*
 * return a value from the URL using the passed value as the key.
 * If the key is not present, return false, otherwise return the
 * value.
 */
GetReplacement( $szTextToReplace )
{
  ....
}

/*
 * return the contents of a file based on the file name passed.
 * If the file does not exist, return false, otherwise return the
 * contents of the file.
 */
GetInclude( $szFileToInclude )
{
  ....
}

Cheers,

Paul 



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