From 9ab8056f789afd7c0b8f500d873b9b535a2067fd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@lysator.liu.se>
Date: Mon, 11 Jul 2022 22:29:42 +0200
Subject: Remove usage of zipper.

---
 module/c/preprocessor2.scm | 40 +++++++++++++++-------------------------
 1 file changed, 15 insertions(+), 25 deletions(-)

(limited to 'module/c')

diff --git a/module/c/preprocessor2.scm b/module/c/preprocessor2.scm
index 71c2a09e..8bec237a 100644
--- a/module/c/preprocessor2.scm
+++ b/module/c/preprocessor2.scm
@@ -19,8 +19,6 @@
   :use-module (c unlex)
   :use-module (c cpp-types)
   :use-module (c cpp-util)
-  :use-module ((c zipper) :select (list-zipper left focused right zip-find-right
-                                               list->zipper zipper->list))
   :export (defined-macro))
 
 (define-syntax-rule (alist-of variable key-type value-type)
@@ -67,38 +65,30 @@
 (define (expand## tokens)
   (typecheck tokens (list-of lexeme?))
 
-  (let loop ((zipper (list->zipper tokens)))
-    (cond ((equal? "##" (punctuator-token? (focused zipper)))
-           (let ((l (drop-whitespace (left zipper)))
-                 (r (drop-whitespace (right zipper))))
+  (let loop ((left '())
+             (right tokens))
+    (cond ((null? right)
+           (reverse left))
+          ((equal? "##" (punctuator-token? (car right)))
+           (let ((l (drop-whitespace left))
+                 (r (drop-whitespace (cdr right))))
              (cond ((or (null? l) (null? r))
                     (scm-error 'cpp-error "expand##"
                                "## can't be first or last token: ~s"
                                (list (unlex tokens)) #f))
                    ((and (placemaker-token? (car l))
                          (placemaker-token? (car r)))
-                    (loop (list-zipper left: (cdr l)
-                                       right: (cdr r)
-                                       focused: (placemaker))))
+                    (loop (cdr l) (cons (placemaker) (cdr r))))
                    ((placemaker-token? (car l))
-                    (loop (list-zipper left: (cdr l)
-                                       right: (cdr r)
-                                       focused: (car r))))
+                    (loop (cdr l) r))
                    ((placemaker-token? (car r))
-                    (loop (list-zipper left: (cdr l)
-                                       right: (cdr r)
-                                       focused: (car l))))
-                   (else
-                    (loop (list-zipper left: (cdr l)
-                                       right: (cdr r)
-                                       focused: (concatenate-tokens
-                                                 (car l) (car r))))))))
-          ((null? (right zipper))
-           (zipper->list zipper))
+                    (loop (cdr l) (cons (car l) (cdr r))))
+                   (else (loop (cdr l) (cons (concatenate-tokens (car l) (car r))
+                                             (cdr r)))))))
           (else
-           (loop (zip-find-right
-                  (lambda (token) (equal? "##" (punctuator-token? token)))
-                  zipper))))))
+           (let ((pre post (break (lambda (token) (equal? "##" (punctuator-token? token)))
+                                  right)))
+             (loop (append left (reverse pre)) post))))))
 
 
 ;; expand function like macro
-- 
cgit v1.2.3