;;; -*- Mode: LISP; Syntax: COMMON-LISP; Package: TBNL; Base: 10 -*-
;;; $Id$

;;; Copyright (c) 2005, Alceste Scalas. All rights reserved.

;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions
;;; are met:

;;;   * Redistributions of source code must retain the above copyright
;;;     notice, this list of conditions and the following disclaimer.

;;;   * Redistributions in binary form must reproduce the above
;;;     copyright notice, this list of conditions and the following
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;;;     provided with the distribution.

;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
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(in-package #:tbnl)

(defmacro create-groups-bind-regex-dispatcher (regex var-list page-function)
  "Works like CREATE-REGEX-DISPATCHER, but PAGE-FUNCTION will be
called with the variables in VAR-LIST used as additional keyword
arguments bound to the corresponding register groups of REGEX.
Note: VAR-LIST has the same format of its omonymous in
CL-PPCRE:REGISTER-GROUPS-BIND, so you can apply some magic here."
  `(let ((scanner (cl-ppcre:create-scanner ,regex)))
     (lambda (request)
       (cl-ppcre:register-groups-bind
	   ,var-list
	   (scanner (script-name request))
	 ;; Iff the regex matches, we return a closure that calls the
	 ;; dispatch function with the proper keyword arguments
	 (lambda () (,page-function ,@(build-keyword-list var-list)))))))

(defun build-keyword-list (var-list)
  "Utility function for CREATE-GROUPS-BIND-REGEX-DISPATCHER.
Build a keyword list out of the var-list, ready to be used to
invoke the dispatcher function"
  (mapcan (lambda (var)
	    (list (intern (symbol-name var) :keyword) var))
	  (cleanup-var-list var-list)))

(defun cleanup-var-list (var-list)
  "Flatten all the \(FUNCTION VAR) entries in VAR-LIST, leaving
only variable names."
  (loop for element in var-list
        if (consp element)
          nconc (loop for var in (rest element)
                      collect var)
        else
          collect element))