From c5cd90347faaeecdebae867df7096fd79d481962 Mon Sep 17 00:00:00 2001
From: "Taylor R. Campbell" <net/mumble/campbell>
Date: Mon, 3 Jul 2006 19:05:02 +0000
Subject: [PATCH] Implement PARSE-STATE-START-OF-SEXP and
 PARSE-STATE-END-OF-SEXP properly in Edwin's partial S-expression parser. 
 This fixes a long- standing bug in paredit whereby character deletion in
 strings that were the first elements of lists would cause segmentation
 faults.

---
 v7/src/edwin/paredit.scm  | 11 +----------
 v7/src/edwin/syntax.scm   | 12 +++++++++++-
 v7/src/microcode/syntax.c | 13 +++++++++----
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/v7/src/edwin/paredit.scm b/v7/src/edwin/paredit.scm
index da9c1b9d3..6b10a29ea 100644
--- a/v7/src/edwin/paredit.scm
+++ b/v7/src/edwin/paredit.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: paredit.scm,v 1.5 2006/06/27 18:43:59 riastradh Exp $
+$Id: paredit.scm,v 1.6 2006/07/03 19:05:02 riastradh Exp $
 
 This code is written by Taylor R. Campbell and placed in the Public
 Domain.  All warranties are disclaimed.
@@ -761,15 +761,6 @@ Both must be lists, strings, or atoms; error if there is mismatch."
                             (buffer-start (current-buffer)))
                         point)))
 
-;++ These are wrong, but, argh, I don't think Edwin preserves enough
-;++ information to make them right.
-
-(define (parse-state-end-of-sexp state)
-  (forward-one-sexp (forward-one-sexp (parse-state-last-sexp state))))
-
-(define (parse-state-start-of-sexp state)
-  (backward-one-sexp (parse-state-end-of-sexp state)))
-
 (define (insert-sexp-pair open close sexps #!optional mark)
 
   (define (insert-space end? mark)
diff --git a/v7/src/edwin/syntax.scm b/v7/src/edwin/syntax.scm
index b60e94aee..1f3a28654 100644
--- a/v7/src/edwin/syntax.scm
+++ b/v7/src/edwin/syntax.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: syntax.scm,v 1.93 2004/11/19 16:59:27 cph Exp $
+$Id: syntax.scm,v 1.94 2006/07/03 19:05:02 riastradh Exp $
 
 Copyright 1987,1989,1991,1992,1996,1997 Massachusetts Institute of Technology
 Copyright 1998,1999,2000,2001,2002,2004 Massachusetts Institute of Technology
@@ -243,6 +243,7 @@ a comment ending."
   ;; COMMENT-START is valid when COMMENT-STATE is not #f.
   (comment-state #f read-only #t)
   (quoted? #f read-only #t)
+  (start-of-sexp #f)
   (last-sexp #f)
   (containing-sexp #f)
   (location #f)
@@ -257,6 +258,11 @@ a comment ending."
       (parse-state-quoted? state)
       (not (= (parse-state-depth state) 0))))
 
+(define (parse-state-end-of-sexp state)
+  (cond ((parse-state-start-of-sexp state)
+         => forward-one-sexp)
+        (else #f)))
+
 (define (forward-to-sexp-start mark end)
   (parse-state-location (parse-partial-sexp mark end 0 #t)))
 
@@ -279,6 +285,10 @@ a comment ending."
 	    (mark-index end)
 	    target-depth stop-before? old-state)))
       ;; Convert the returned indices to marks.
+      (if (parse-state-start-of-sexp state)
+          (set-parse-state-start-of-sexp!
+           state
+           (make-mark group (parse-state-start-of-sexp state))))
       (if (parse-state-last-sexp state)
 	  (set-parse-state-last-sexp! 
 	   state 
diff --git a/v7/src/microcode/syntax.c b/v7/src/microcode/syntax.c
index c4b5cd918..76e699754 100644
--- a/v7/src/microcode/syntax.c
+++ b/v7/src/microcode/syntax.c
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Id: syntax.c,v 1.30 2005/07/16 03:46:42 cph Exp $
+$Id: syntax.c,v 1.31 2006/07/03 19:05:02 riastradh Exp $
 
 Copyright 1987,1988,1989,1991,1993,1996 Massachusetts Institute of Technology
 Copyright 2000,2004,2005 Massachusetts Institute of Technology
@@ -1059,19 +1059,24 @@ DEFINE_PRIMITIVE ("SCAN-SEXPS-FORWARD", Prim_scan_sexps_forward, 7, 7, 0)
   FAST_VECTOR_SET (result, 3, (BOOLEAN_TO_OBJECT (quoted)));
   FAST_VECTOR_SET
     (result, 4,
+     (((level -> last) == NULL)
+      ? SHARP_F
+      : (LONG_TO_UNSIGNED_FIXNUM ((SCAN_TO_INDEX (level -> last)) - 1))));
+  FAST_VECTOR_SET
+    (result, 5,
      (((level -> previous) == NULL)
       ? SHARP_F
       : (LONG_TO_UNSIGNED_FIXNUM ((SCAN_TO_INDEX (level -> previous)) - 1))));
   FAST_VECTOR_SET
-    (result, 5,
+    (result, 6,
      (((level == level_start) || (((level - 1) -> last) == NULL))
       ? SHARP_F
       : (LONG_TO_UNSIGNED_FIXNUM
 	 ((SCAN_TO_INDEX ((level - 1) -> last)) - 1))));
   FAST_VECTOR_SET
-    (result, 6, (LONG_TO_UNSIGNED_FIXNUM (SCAN_TO_INDEX (start))));
+    (result, 7, (LONG_TO_UNSIGNED_FIXNUM (SCAN_TO_INDEX (start))));
   FAST_VECTOR_SET
-    (result, 7,
+    (result, 8,
      ((in_comment == 0)
       ? SHARP_F
       : (LONG_TO_UNSIGNED_FIXNUM (SCAN_TO_INDEX (comment_start)))));
-- 
2.25.1