csys/space: loc-iterator for scanning space around a location

csys/space.lisp

@@ -6,7 +6,8 @@
   (:local-nicknames (:alx :alexandria)
                     (:util :scopes/util))
   (:export #:create #:put #:del #:fetch #:query 
-           #:neighbors #:free-loc-at #:distance-sq))
+           #:neighbors #:free-loc-at #:distance-sq
+           #:loc-iterator))
 
 (in-package :scopes/csys/space)
 
@@ -29,9 +30,37 @@
 (defun query (spc pattern)
   nil)
 
-(defun neighbors (spc loc &key (dist 2)))
+(defun neighbors (spc loc &key (dist 2))
+  (let* ((from (floor (sqrt dist)))
+         (to (- from)))
+    )
+  )
 
 (defun free-loc-at (spc loc &key (dist 2)))
 
 (defun distance-sq (spc loc1 loc2))
 
+(defun do-it (it fn)
+  (let (v)
+    (loop
+      (setf v (funcall it))
+      (if v
+        (funcall fn v)
+        (return)))))
+
+(defun loc-iterator (from to &key (dims 2))
+  (labels (
+    (inc (cur idx)
+      (when (< idx dims)
+        (let ((new (1+ (aref cur idx))))
+          (setf (aref cur idx) new)
+          (when (> new to)
+            (setf (aref cur idx) from)
+            (setf cur (inc cur (1+ idx))))
+          cur))))
+    (let ((cur (make-array dims :initial-element from)))
+      (lambda ()
+        (when cur
+          (prog1 (make-array dims :initial-contents cur)
+            (setf cur (inc cur 0))))))))
+

test/test-csys.lisp

@@ -87,6 +87,14 @@
     (== (space:fetch spc #(1 2)) 46)
     (space:del spc #(1 1))
     (== (space:fetch spc #(1 1)) nil)
+    (let ((it (space:loc-iterator -1 1))
+          loc all)
+      (loop 
+        (setf loc (funcall it))
+        (if loc
+          (push loc all)
+          (return)))
+      (print all))
     ))
  
 (deftest test-basic-0 ()