Changeset trunk,24

Timestamp:

06/24/2007 01:48:00 AM (19 years ago)

Author:

dsowen

revision id:

svn-v3-trunk0:2948df59-2b31-0410-8e06-c40c0b09d5b6:trunk:24

Message:

Recognize symbols by name instead of identity.

Location:

trunk

Files:

• matching.lisp (modified) (1 diff)
• util.lisp (modified) (1 diff)

trunk/matching.lisp

@@ -234 +234 @@
     (list
      (destructuring-bind (head . tail) rule
-       (case head
+       (symcase head
          (^ (destructuring-bind (regex) tail
               `(if-matches-regex ,input ,regex (,next ,match) ,then ,else)))

trunk/util.lisp

@@ -40 +40 @@
     ((not ,cond))
     ,@body))
+
+(defmacro symcase (symvar &body clauses)
+  (flet ((is-default (clause)
+           (string= (symbol-name (first clause)) #.(symbol-name 't))))
+    (let ((symname (gensym))
+          (default-clause (find-if #'is-default clauses)))
+      `(let ((,symname (symbol-name ,symvar)))
+        (cond
+          ,@(mapcar (lambda (clause)
+                      (destructuring-bind (sym form) clause
+                        `((string= ,symname ,(symbol-name sym)) ,form)))
+                    (remove-if #'is-default clauses))
+          ,@(when default-clause
+                  (destructuring-bind (sym form) default-clause
+                    `((,sym ,form)))))))))