3 files changed, 38 insertions(+), 13 deletions(-)

M fs/doc/tips.txt
M fs/text/ed.fs
M fs/text/ged.fs

@@ 8,3 8,14 @@ and "key" are there) of your init, you can create a fork of it to allow you to
 boot to the old init if needed. Example:
 
     key 'z' = [if] f<< /init2.fs \s [then]
+
+## next
+
+If you want to save yourself some painful debugging sessions, don't ever call a
+struct field "next" or, if you do, make sure that this struct doesn't ever
+define words in its namespace, otherwise it overrides core's "next" and all hell
+breaks loose, sometimes (that's the worst), in subtle ways!
+
+This can happen when describing a structure that is a linked list. Name this
+field anything but "next", you probably won't use it anyways as iterating over a
+LL is clearer with "llnext" anyways.

@@ 6,9 6,15 @@
 : nspcs ( n -- ) ?dup if >r begin SPC stdout next then ;
 
 struct[ Line
-  sfield next
+  sfield _next
   sfield cnt
   sfield ptr
+
+  : :itern ( n line -- iter-n line )
+    over not if exit then over >r \ V1=asked-n
+    swap >r begin ( line )
+      dup llnext ?dup if nip else r> r> -^ swap exit then next ( line )
+    r> swap ;
 ]struct
 
 extends IO struct[ Edbuf


@@ 27,10 33,10 @@ extends IO struct[ Edbuf
   : _cbounds ( self -- ) dup cpos over sel Line cnt min swap to cpos ;
   : _sel! ( line self -- ) tuck to sel _cbounds ;
   : :godown ( n self -- )
-    over if swap >r dup sel begin ( self line )
-        dup llnext if llnext over 1 swap to+ lpos else leave then next
-      else nip dup lines then ( self line )
-    swap _sel! ;
+    over not if 2drop exit then ( n self )
+    swap >r dup sel begin ( self line )
+      dup llnext if llnext over 1 swap to+ lpos else leave then next
+    ( self line ) swap _sel! ;
 
   : _eol? ( self -- f ) dup cpos swap sel Line cnt = ;
   : _eof? ( self -- f ) dup sel llnext not swap _eol? and ;


@@ 65,8 71,7 @@ extends IO struct[ Edbuf
 
   : :empty ( self -- )
     dup buf Arena :reset
-    0 over to cpos
-    dup _newline swap 2dup to lines to sel ;
+    dup _newline over to lines _sel$$ ;
 
   : :new ( -- edbuf )
     Arena :new here ( arena edbuf )

@@ 9,11 9,20 @@ require /sys/grid.fs
   dup if swap Line ptr over grid :write else nip then ( n )
   grid COLS -^ ?dup if nspcs then grid :spitoff ;
 
-: _spitpage ( -- )
-  grid LINES 1- >r 0 edbuf sel begin ( lineno line )
-    dup if over grid COLS * over _spitline else over grid :clrline then
-    dup if llnext then swap 1+ swap next 2drop
-  edbuf cpos grid :pos! ;
+: _spitpage ( fromline -- )
+  grid LINES 1- >r 0 swap begin ( lineno line )
+   dup if over grid COLS * over _spitline else over grid :clrline then
+  dup if llnext then swap 1+ swap next 2drop ;
+
+0 value _top
+: _top! ( lineno -- )
+  dup to _top edbuf lines Line :itern nip _spitpage ;
+: _zoom ( -- )
+  _top edbuf lpos tuck > if _top! else ( lpos )
+    grid LINES 1- - max0 _top over <= if _top! else drop then then ;
+
+: _refresh ( -- )
+  _zoom edbuf lpos _top - grid COLS * edbuf cpos + grid :pos! ;
 
 S" qhjklHL[]" const KEYS
 KEYS c@ wordtbl handlers


@@ 28,5 37,5 @@ KEYS c@ wordtbl handlers
 :w pagesz edbuf :godown ;
 
 : ged begin
-    _spitpage key KEYS c@+ [c]? ( idx )
+    _refresh key KEYS c@+ [c]? ( idx )
     dup 0>= if handlers swap wexec else drop then again ;=
\ No newline at end of file