From f182f02b5a9ffe3d59ee886e777b5f9b7a3b8b85 Mon Sep 17 00:00:00 2001
From: Eitaro Fukamachi <e.arrows@gmail.com>
Date: Fri, 13 Mar 2015 12:43:12 +0900
Subject: [PATCH] Fix Lack.builder to handle normal forms properly.

---
 src/builder.lisp | 76 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 50 insertions(+), 26 deletions(-)

diff --git a/src/builder.lisp b/src/builder.lisp
index 592c9d7..ece6356 100644
--- a/src/builder.lisp
+++ b/src/builder.lisp
@@ -22,38 +22,62 @@
           (symbol-value mw-symbol)
           (error "Middleware ~S is unbound or not a function" mw-symbol)))))
 
+(defun clack-middleware-symbol-p (symbol)
+  (and (symbolp symbol)
+       (find-package :clack.middleware)
+       (find-class symbol nil)
+       (subtypep (find-class symbol)
+                 (intern (string :<middleware>)
+                         :clack.middleware))))
+
+(defun convert-to-middleware-form (mw)
+  (let ((app (gensym "APP")))
+    (typecase mw
+      (null)
+      (function mw)
+      (keyword `(find-middleware ,mw))
+      ;; for old Clack middlewares
+      (symbol (if (clack-middleware-symbol-p mw)
+                  `(lambda (,app)
+                     (funcall (intern (string :wrap) :clack)
+                              (make-instance ',mw)
+                              ,app))
+                  mw))
+      (cons
+       (typecase (car mw)
+         (keyword `(lambda (,app)
+                     (funcall (find-middleware ,(car mw)) ,app
+                              ,@(cdr mw))))
+         (symbol
+          ;; for old Clack middlewares
+          (if (clack-middleware-symbol-p (car mw))
+              `(lambda (,app)
+                 (funcall (intern (string :wrap) :clack)
+                          (make-instance ',mw ,@(cdr mw))
+                          ,app))
+              ;; Normal form
+              (let ((res (gensym "RES")))
+                ;; reconvert the result of the form
+                `(let ((,res ,mw))
+                   (typecase ,res
+                     (keyword (find-middleware ,res))
+                     (cons (if (keywordp (car ,res))
+                               `(lambda (,',app)
+                                  (apply (find-middleware (car ,,res)) ,',app
+                                         (cdr ,,res)))
+                               ,res))
+                     (otherwise ,res))))))
+         (otherwise mw)))
+      (otherwise mw))))
+
 (defmacro builder (&rest app-or-middlewares)
-  (let ((middlewares (butlast app-or-middlewares))
-        (app (gensym "APP")))
+  (let ((middlewares (butlast app-or-middlewares)))
     `(reduce #'funcall
              (remove-if
               #'null
               (list
                ,@(loop for mw in middlewares
                        when mw
-                         collect (typecase mw
-                                   (null)
-                                   (function mw)
-                                   (keyword `(find-middleware ,mw))
-                                   ;; for old Clack middlewares
-                                   (symbol `(lambda (,app)
-                                              (funcall (intern (string :wrap) :clack)
-                                                       (make-instance ',mw)
-                                                       ,app)))
-                                   (cons
-                                    ;; for `cl:lambda' and `cl:if' forms
-                                    (if (eq (symbol-package (car mw)) (find-package :cl))
-                                        mw
-                                        (typecase (car mw)
-                                          (keyword `(lambda (,app)
-                                                      (funcall (find-middleware ,(car mw)) ,app
-                                                               ,@(cdr mw))))
-                                          ;; for old Clack middlewares
-                                          (symbol `(lambda (,app)
-                                                     (funcall (intern (string :wrap) :clack)
-                                                              (make-instance ',mw ,@(cdr mw))
-                                                              ,app)))
-                                          (otherwise mw))))
-                                   (otherwise mw)))))
+                         collect (convert-to-middleware-form mw))))
              :initial-value ,(car (last app-or-middlewares))
              :from-end t)))