From f8c1db21925b95c4d86dca0e3f49f937e99aeb15 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Renaud=20Casenave-P=C3=A9r=C3=A9?= <renaud@casenave-pere.fr>
Date: Wed, 25 Mar 2015 23:25:25 +0100
Subject: [PATCH] Add helpers for let handler

---
 src/render/shader/walker.lisp | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/render/shader/walker.lisp b/src/render/shader/walker.lisp
index 143b073..1e5b774 100644
--- a/src/render/shader/walker.lisp
+++ b/src/render/shader/walker.lisp
@@ -27,6 +27,26 @@
   "Retreive the handler for the symbol FIRST."
   (gethash first *form-handlers* *default-handler*))
 
+(defun binding-to-symbol (binding)
+  (let ((name (safe-first binding)))
+    (cond ((listp name)
+           (assert (eq 'setf (first name)))
+           (check-type (second name) symbol)
+           (second name))
+          (t
+           name))))
+
+(defmacro with-imposed-bindings (&body body)
+  #-sbcl
+  `(locally ,@body)
+  #+sbcl
+  (destructuring-bind ((binder bindings &rest binder-body))
+      body
+    `(locally
+         (declare (sb-ext:disable-package-locks
+                   ,@(mapcar 'binding-to-symbol bindings)))
+       (,binder ,bindings ,@binder-body))))
+
 (defun function-name-p (name)
   "Return whether NAME is the name of a function."
   (or (symbolp name)