From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thorsten Jolitz <tjolitz@gmail.com>
Subject: Re: Circular lists/shared structures in org-element parse-tree
Date: Fri, 28 Jun 2013 23:59:27 +0200
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Daimrod <daimrod@gmail.com> writes:

> Thorsten Jolitz <tjolitz@gmail.com> writes:

[...]

>> but when processing the parse tree as a list in elisp, how can I
>> detect the fact that
>>
>> ,------------
>> | :parent #2#
>> `------------
>>
>> refers to 
>>
>> ,-----------------
>> | #2=(org-data nil
>> `-----------------
>>
>> i.e. points back to an already existing structure?
>
> AFAIK you have to track all pointers inspected to see if one has already
> be seen.
>
> For example, I've implemented a version of equal[1] to compare this kind
> of lists (to add tests to org-sync).
>
> [1]
> https://github.com/daimrod/Emacs-config/blob/master/elisp/dmd-utils.el#L25

Oh my ... I knew this would complicate my life a bit ...

Thanks for the link, this example function is indeed very helpful. 

-- 
cheers,
Thorsten