base, optparse: Introduce `case2' macros.

  * base: Add new `case2' macro, for fetching two values, switching on
    one and binding the other.  Also add `ecase2' to do the obvious
    thing.

  * optparse: Rewrite `do-options' to use `ecase2' (or `case2').

diff --git a/mdw-base.lisp b/mdw-base.lisp
index 72b5b06..bbe7662 100644 (file)
--- a/mdw-base.lisp
+++ b/mdw-base.lisp
@@ -33,7 +33,7 @@
           #:stringify #:listify #:fix-pair #:pairify
           #:whitespace-char-p
           #:slot-uninitialized
-          #:nlet #:while
+          #:nlet #:while #:case2 #:ecase2
           #:with-gensyms #:let*/gensyms #:with-places
           #:locp #:locf #:ref #:with-locatives
           #:update-place #:update-place-after
@@ -152,6 +152,35 @@ gensyms will be bound to the corresponding VALUE."
      (unless ,cond (return))
      ,@body))
 
+(compile-time-defun do-case2-like (kind vform clauses)
+  "Helper function for `case2' and `ecase2'."
+  (with-gensyms (scrutinee argument)
+    `(multiple-value-bind (,scrutinee ,argument) ,vform
+       (declare (ignorable ,argument))
+       (,kind ,scrutinee
+        ,@(mapcar (lambda (clause)
+                    (destructuring-bind
+                        (cases (&optional var) &rest forms)
+                        clause
+                      `(,cases
+                        ,@(if var
+                              (list `(let ((,var ,argument)) ,@forms))
+                              forms))))
+                  clauses)))))
+
+(defmacro case2 (vform &body clauses)
+  "VFORM is a form which evaluates to two values, SCRUTINEE and ARGUMENT.
+The CLAUSES have the form (CASES ([VAR]) FORMS...), where a standard `case'
+clause has the form (CASES FORMS...).  The `case2' form evaluates the VFORM,
+and compares the SCRUTINEE to the various CASES, in order, just like `case'.
+If there is a match, then the corresponding FORMs are evaluated with VAR (if
+specified) bound to the value of ARGUMENT."
+  (do-case2-like 'case vform clauses))
+
+(defmacro ecase2 (vform &body clauses)
+  "Like `case2', but signals an error if no clause matches the SCRUTINEE."
+  (do-case2-like 'ecase vform clauses))
+
 ;;;--------------------------------------------------------------------------
 ;;; with-places
 

diff --git a/optparse.lisp b/optparse.lisp
index e337fc0..d5e2f10 100644 (file)
--- a/optparse.lisp
+++ b/optparse.lisp
@@ -941,31 +941,19 @@ and respond to them properly."
        (full-usage (setf *usage* full-usage))))
 
 (defmacro do-options ((&key (parser '(make-option-parser))) &body clauses)
-  (with-gensyms (topt targ tparser)
-    (flet ((frob (clause)
-            (destructuring-bind
-                (case (&optional arg) &rest forms)
-                clause
-              (and case 
-                   (list `(,case ,@(if arg
-                                       `(let ((,arg ,targ)) ,@forms)
-                                       forms)))))))
-      `(let ((,tparser ,parser))
-        (loop
-          (multiple-value-bind (,topt ,targ) (option-parse-next ,tparser)
-            (declare (ignorable ,targ))
-            (unless ,topt (return))
-            (case ,topt
-              ,@(mapcan #'frob clauses))))
-        ,@(let ((tail (find nil clauses :key #'car)))
-            (and tail
-                 (destructuring-bind
-                     ((&optional arg) &rest forms)
-                     (cdr tail)
-                   (list (if arg
-                             `(let ((,arg (option-parse-remainder
-                                           ,tparser)))
-                                ,@forms)
-                             forms)))))))))
+  (with-gensyms (tparser)
+    `(let ((,tparser ,parser))
+       (loop
+        (,(if (find t clauses :key #'car) 'case2 'ecase2)
+            (option-parse-next ,tparser)
+          ((nil) () (return))
+          ,@(remove-if #'null clauses :key #'car)))
+       ,@(let ((tail (find nil clauses :key #'car)))
+          (and tail
+               (destructuring-bind ((&optional arg) &rest forms) (cdr tail)
+                 (if arg
+                     (list `(let ((,arg (option-parse-remainder ,tparser)))
+                              ,@forms))
+                     forms)))))))
 
 ;;;----- That's all, folks --------------------------------------------------