Let custom_url_rewrite operate on querystring and fragment

It would be nice to get a list of places calling drupal_get_path_alias(), so we can see what is affected by moving the URL rewrite from the lookup function to url(). It sounds like a good API cleanup to have custom_url_rewrite() called from url(), as the name indicates, but the current use cases should be checked.

Although the changes you offer seem to be logical and straightforward, I am not entirely comfortable with saying "yes, sure", as I don't have knowledge about how contributed modules utilize aliasing, especially i18n related modules. It would be nice to post grep into a contrib checkout and/or ask Jose Reyero and Roberto Gerola to comment on this change.

I have concerns. First of all, the current system lets you access the path before and after aliasing. This is important because if someone adds an alias to a system path you are rewriting then you rewriter is screwed. Second the list(a, b) = foo(a,b) construct is ugly, just call foo(a, b) and get them by reference.

I much love this patch. As path_nodeapi shows, things get simplified. Also, custom_url_rewrite will be easier to use and more powerful because it change options.

About the language modules using this mechanism, I think we shouldn't worry too much about them, as now that all is handled nicely by Drupal core, so they won't need that anymore.

Also, completely ok with the change in node module, I'd say that's actually a current bug, as we were missing node language for that aliasing and better if we don't do direct queries in there and use the api.

However, based in past experience messing with paths, languages and i18n, I think that if you want to allow some module full control over paths/aliases/urls, what we rather need is some hook in url similar to what we've done for the language system.

function url($path = NULL, $options = array()) { 
....
  // Give modules control over this. We run it before language_url_rewrite so modules can even switch language for paths depending on other parameters (groups?)
  if (function_exists('custom_url_rewrite')) {
    custom_url_rewrite($path, $options);
  }

  // May need language dependant rewriting if language.inc is present
  if (function_exists('language_url_rewrite')) {
    language_url_rewrite($path, $options);
  }

And then we might use one more hook in drupal_get_normal_path, and drupal_get_path_alias, but I'd put it before calling drupal_get_path alias, so it allows much more control over the process of path aliasing. This way your module can call itself drupal_lookup_path if needs to.

function drupal_get_path_alias($path, $path_language = '') {

  if (function_exists('custom_lookup_path') && $alias = custom_lookup_path('alias', $path, $path_language) {
    return $alias;
  }  
  if ($alias = drupal_lookup_path('alias', $path, $path_language)) {
    return $alias;
  }

  return $path;
}

And same for drupal_get_normal_path().
(And btw, a module could also skip alias searching quieries for certain known paths allowing some optimization here)

Although the introduced asymmetry (of alias and original path lookups) does not look entirely logical, I don't know a better way to deal with it, so fixed the punctuation problems in the code comments and committed.

Please update the module update instructions. I leave this code needs work until it is done.