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From: Andrey Borzenkov <arvidjaar@gmail.com>
To: zsh-workers@zsh.org
Subject: Re: LinkList implementation
Date: Sun, 28 Feb 2010 12:06:47 +0300
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Cc: Michael Hwang <michael.a.hwang@gmail.com>
References: <22a0ef081002271433u713e1923lb04c7d1bf369d3d0@mail.gmail.com>
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On Sunday 28 of February 2010 01:33:24 Michael Hwang wrote:
> In the process of writing a new builtin, I discovered an oddity of
> zsh's implementation of LinkList, which is a doubly linked list.
>=20
> LinkList alist =3D newlinklist();
> LinkNode node;
> for (node =3D lastnode(alist); node; decnode(alist)) {
>      ((SomeStructPointer) getdata(node))->someField;
> }
>=20
BTW decnode applies to node, not list - it should be decnode(node)

> Since no nodes have been added to the LinkList, one would expect the
> body of the loop to not run at all.

Well, you have to accept that and use another termination condition,=20
like e.g. in zle_hist.c:isearch_newpos():

        for (node =3D lastnode(matchlist);
             node !=3D (LinkNode)matchlist; decnode(node)) {

=46or the sake of purity this actually should be
             node !=3D &matchlist->node

The games linklist.c plays are really daunting ... but to change it now=20
you have to carefully go through all of code to adjust snippets like=20
above.

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