Add GET-PROPERTIES, GETF and (SETF GETF).

The SETF expander for GETF is weird though.

diff --git a/src/list.lisp b/src/list.lisp
index 58226f8..9cb8e45 100644 (file)
--- a/src/list.lisp
+++ b/src/list.lisp
@@ -360,3 +360,51 @@
       (when (member (funcall key x) list2 :test test :key key)
         (push x new-list)))
     new-list))
+
+(defun get-properties (plist indicator-list)
+  (do* ((plist plist (cddr plist))
+        (cdr (cdr plist) (cdr plist))
+        (car (car plist) (car plist)))
+      ((null plist) (values nil nil nil))
+    (when (null cdr)
+      (error "malformed property list ~S" plist))
+    (let ((found (member car indicator-list :test #'eq)))
+      (when found
+        (return (values car (cadr plist) plist))))))
+
+(defun getf (plist indicator &optional default)
+  (do* ((plist plist (cddr plist))
+        (cdr (cdr plist) (cdr plist))
+        (car (car plist) (car plist)))
+      ((null plist) default)
+    (when (null cdr)
+      (error "malformed property list ~S" plist))
+    (when (eq indicator car)
+      (return (cadr plist)))))
+
+(defun %putf (plist indicator new-value)
+  (do* ((tail plist (cddr tail))
+        (cdr (cdr tail) (cdr tail))
+        (car (car tail) (car tail)))
+      ((null tail) (list* indicator new-value plist))
+    (when (null cdr)
+      (error "malformed property list ~S" tail))
+    (when (eq indicator car)
+      ;; TODO: should be cadr, needs a defsetf for that
+      (setf (car (cdr tail)) new-value)
+      (return tail))))
+
+(define-setf-expander getf (plist indicator &optional default)
+  (multiple-value-bind (dummies vals newval setter getter)
+      (get-setf-expansion plist)
+    (let ((store (gensym))
+          (indicator-sym (gensym))
+          (default-sym (and default (gensym))))
+      (values `(,indicator-sym ,@(and default `(,default-sym)) ,@dummies)
+              `(,indicator ,@(and default `(,default)) ,@vals)
+              `(,store)
+              `(let ((,(car newval) (%putf ,getter ,indicator-sym ,store))
+                     ,@(cdr newval))
+                 ,setter
+                 ,store)
+              `(getf ,getter ,indicator-sym ,@(and default `(,default-sym)))))))

diff --git a/tests/list.lisp b/tests/list.lisp
index ffc672d..b59f662 100644 (file)
--- a/tests/list.lisp
+++ b/tests/list.lisp
@@ -217,3 +217,14 @@
 (test (let (foo)
         (mapc (lambda (x y z) (push (+ x y z) foo)) '(1 2) '(3) '(4 5 6))
         (equal foo '(8))))
+
+;; GETF
+(test (eq (getf '(a b c d) 'a) 'b))
+(test (null (getf '(a b c d) 'e)))
+(test (equal (let ((x (list 'a 1))) (setf (getf x 'a) 3) x) '(a 3)))
+(test (equal (let ((x (list 'a 1))) (incf (getf x 'a)) x) '(a 2)))
+
+;; GET-PROPERTIES
+(test (equal (multiple-value-list (get-properties '(a b c d) '(b d e))) '(NIL NIL NIL)))
+(test (equal (multiple-value-list (get-properties '(a b c d) '(b a c))) '(a b (a b c d))))
+(test (equal (multiple-value-list (get-properties '(a b c d) '(b c a))) '(a b (a b c d))))