From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on
	ip-172-31-74-118.ec2.internal
X-Spam-Level: *
X-Spam-Status: No, score=1.5 required=3.0 tests=BAYES_50,FREEMAIL_FROM,
	FROM_STARTS_WITH_NUMS autolearn=no autolearn_force=no
	version=3.4.5-pre1
X-Received: by 2002:a05:620a:135c:: with SMTP id c28mr3790640qkl.441.1613652892278;
        Thu, 18 Feb 2021 04:54:52 -0800 (PST)
X-Received: by 2002:a25:b906:: with SMTP id x6mr5893220ybj.504.1613652892027;
 Thu, 18 Feb 2021 04:54:52 -0800 (PST)
Path: eternal-september.org!reader02.eternal-september.org!aioe.org!news.dns-netz.com!news.freedyn.net!newsreader4.netcologne.de!news.netcologne.de!peer04.ams1!peer.ams1.xlned.com!news.xlned.com!peer01.iad!feed-me.highwinds-media.com!news.highwinds-media.com!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Thu, 18 Feb 2021 04:54:51 -0800 (PST)
In-Reply-To: <84c3e8ee-e4e9-4402-8da6-e43a44eca66bn@googlegroups.com>
Complaints-To: groups-abuse@google.com
Injection-Info: google-groups.googlegroups.com; posting-host=82.154.189.75; posting-account=rhqvKAoAAABpikMmPHJSZh4400BboHwT
NNTP-Posting-Host: 82.154.189.75
References: <fe533430-6f7c-4f41-a202-0251d5ca46a4n@googlegroups.com>
 <1b206764-967c-4b1b-af9c-61a0cd0750fcn@googlegroups.com> <84c3e8ee-e4e9-4402-8da6-e43a44eca66bn@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <f3d5e634-39e4-4c60-8f28-bb111df8391dn@googlegroups.com>
Subject: Re: can't understand how to move a node of a linked list to another
 place on the same
From: Mehdi Saada <00120260a@gmail.com>
Injection-Date: Thu, 18 Feb 2021 12:54:52 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Received-Bytes: 3406
Xref: reader02.eternal-september.org comp.lang.ada:61374
List-Id: <comp.lang.ada>

Le jeudi 18 f=C3=A9vrier 2021 =C3=A0 08:06:57 UTC+1, gautier...@hotmail.com=
 a =C3=A9crit=C2=A0:
> > No, I'll run it on paper first, please don't bother yet.
> That's actually the fun part with linked lists.
=20
> That's actually the fun part with linked lists.=20
I hate that to no end.

I did put up quite the effort so non-ashamedly I beg for help.
Here's it running on paper. Of course it's wrong 'cause the actual result i=
s still A disappearing.

   procedure insertion_X_on_place_Y (Before_X, Before_Y: in t_List) is
      A: constant t_List :=3D Before_X.next;
      Y: constant t_List :=3D Before_Y.next;
   Begin
      Before_X.next :=3D Before_X.next.next;
      X.next :=3D Y;
      Before_Y.next :=3D X;
   end insertion_X_on_place_Y;

Before running:
X		(x)->(x+1)->..
Y		(y)->(y+1)->..
Before_X	(x-1)->(x)->(x+1)...->(Y-1)->(Y)->(y+1)..
Before_X.next	(x)->(x+1)...->(Y-1)->(Y)->(y+1)..
Before_Y	(Y-1)->(Y)->(y+1)..
Before_Y.next	(Y)->(y+1)..

But: I want (x-1)->(x+1)...->(Y-1)->(x)-> (Y)->(y+1)..

Before_X.next :=3D X.next;

X		(x)->(x+1)->..
Y		(y)->(y+1)->..
Before_X	(x-1)-> (x+1)...->(Y-1)->(Y)->(y+1)..
Before_X.next	(x+1)...->(Y-1)->(Y)->(y+1)..
Before_Y	(Y-1)->(Y)->(y+1)..
Before_Y.next	(Y)->(y+1)..

X.next :=3D Y;

X		(x)->(y)->(y+1)->..
Y		(y)->(y+1)->..
Before_X	(x-1)-> (x+1)...->(Y-1)->(Y)->(y+1)..
Before_X.next	(x+1)...->(Y-1)->(Y)->(y+1)..
Before_Y	(Y-1)->(Y)->(y+1)..
Before_Y.next	(Y)->(y+1)..

Before_Y.next :=3D X;

X		(x)->(y)->(y+1)->..
Y		(y)->(y+1)->..
Before_X	(x-1)-> (x+1)...->(Y-1)->(x)->(y)->(y+1)->..
Before_X.next	(x+1)...->(Y-1)->(x)->(y)->(y+1)->..
Before_Y	(Y-1)->(x)->(y)->(y+1)->..
Before_Y.next	(x)->(y)->(y+1)->..
It SHOULD be ok.

then I display it:
insertion_A_on_place_b(List, List.next);
   ITERATOR :=3D List;
   while ITERATOR /=3D null loop
      Put(ITERATOR.value'Image & ' ');
      ITERATOR :=3D ITERATOR.next;
   end loop;

'1'=20
'3'=20
'4'=20
'5'=20

PLEASE HELP.