collect, unix: Rename `mdw.collect' package to just `collect'.

[lisp] / mdw-base.lisp

diff --git a/mdw-base.lisp b/mdw-base.lisp
index 4d67b7ae2498241a4299985090665254d99d1edb..bbe7662ed98a6bea659fb9d3ac522021f9a58b98 100644 (file)
--- a/mdw-base.lisp
+++ b/mdw-base.lisp
@@ -33,6 +33,7 @@ (defpackage #:mdw.base
           #:stringify #:listify #:fix-pair #:pairify
           #:whitespace-char-p
           #:slot-uninitialized
+          #:nlet #:while #:case2 #:ecase2
           #:with-gensyms #:let*/gensyms #:with-places
           #:locp #:locf #:ref #:with-locatives
           #:update-place #:update-place-after
@@ -98,24 +99,6 @@ (defun whitespace-char-p (ch)
     ((#\space #\tab #\newline #\return #\vt #\formfeed) t)
     (t nil)))
 
-(defmacro nlet (name binds &body body)
-  "Scheme's named let."
-  (multiple-value-bind (vars vals)
-      (loop for bind in binds
-           for (var val) = (pairify bind nil)
-           collect var into vars
-           collect val into vals
-           finally (return (values vars vals)))
-    `(labels ((,name ,vars
-               ,@body))
-       (,name ,@vals))))
-
-(defmacro while (cond &body body)
-  "If COND is false, evaluate to nil; otherwise evaluate BODY and try again."
-  `(loop
-     (unless `cond (return))
-     ,@body))
-
 (declaim (ftype (function nil ()) slot-unitialized))
 (defun slot-uninitialized ()
   "A function which signals an error.  Can be used as an initializer form in
@@ -148,6 +131,56 @@ (defmacro let*/gensyms (binds &body body)
         `(progn ,@body)
         (car (more (mapcar #'pairify (listify binds)))))))
 
+;;;--------------------------------------------------------------------------
+;;; Some simple yet useful control structures.
+
+(defmacro nlet (name binds &body body)
+  "Scheme's named let."
+  (multiple-value-bind (vars vals)
+      (loop for bind in binds
+           for (var val) = (pairify bind nil)
+           collect var into vars
+           collect val into vals
+           finally (return (values vars vals)))
+    `(labels ((,name ,vars
+               ,@body))
+       (,name ,@vals))))
+
+(defmacro while (cond &body body)
+  "If COND is false, evaluate to nil; otherwise evaluate BODY and try again."
+  `(loop
+     (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