lua: string.byte(s,i,j) supports ranges, returns multi-values

2026-04-25 01:10:30 +00:00
parent 702e7c8eac
commit fad44ca097
4 changed files with 53 additions and 34 deletions
--- a/lib/lua/runtime.sx
+++ b/lib/lua/runtime.sx
@@ -990,10 +990,28 @@
  lua-string-byte
  (fn (&rest args)
    (let ((s (first args))
-          (i (if (> (len args) 1) (nth args 1) 1)))
-      (cond
-        ((or (< i 1) (> i (len s))) nil)
-        (else (char-code (char-at s (- i 1))))))))
+          (i-raw (if (> (len args) 1) (nth args 1) nil))
+          (j-raw (if (> (len args) 2) (nth args 2) nil)))
+      (let ((i (if (= i-raw nil) 1 i-raw)))
+        (let ((j (if (= j-raw nil) i j-raw)))
+          (let ((slen (len s)))
+            (let ((ni (cond ((< i 0) (+ slen i 1)) ((= i 0) 1) (else i)))
+                  (nj (cond ((< j 0) (+ slen j 1)) (else j))))
+              (cond
+                ((or (< ni 1) (> ni slen) (< nj ni)) nil)
+                ((= ni nj) (char-code (char-at s (- ni 1))))
+                (else
+                  (let ((out (list (quote lua-multi))))
+                    (begin
+                      (define
+                        b-loop
+                        (fn (k)
+                          (when (and (<= k nj) (<= k slen))
+                            (begin
+                              (set! out (append out (list (char-code (char-at s (- k 1))))))
+                              (b-loop (+ k 1))))))
+                      (b-loop ni)
+                      out)))))))))))

 (define
  lua-char-one