From: Natasha Kerensikova <lithiumcat@gmail.com>
Subject: Re: S-expression I/O in Ada
Date: Thu, 19 Aug 2010 08:09:04 +0000 (UTC)
Date: 2010-08-19T08:09:04+00:00 [thread overview]
Message-ID: <slrni6ppl0.dki.lithiumcat@sigil.instinctive.eu> (raw)
In-Reply-To: i4h7ir$294b$1@adenine.netfront.net
On 2010-08-18, Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org> wrote:
> On 08/18/2010 03:49 AM, Natasha Kerensikova wrote:
>>
>> I have indeed forgotten about Ada containers. However after having read
>> A.18.2 and A.18.3, it seems to me that Doubly_Linked_Lists are more
>> appropriate than vectors: the recursive structure of S-expressions can
>> make assignment (i.e. deep copies) quite expensive, and
>> Doubly_Linked_Lists seem designed primarily to avoid copy of contained
>> objects (though I may be mistaken). Usual operations on S-expressions
>> are append and traversal, on which Vectors don't provide a significant
>> improvement (unlike e.g. random access).
>>
>> Does it make sense or am I missing something?
>
> You're mistaken about Doubly_Linked_Lists not doing a deep copy; on the other
> hand, adding an element to a Vector may cause reallocation with an internal
> copy, which lists avoid.
Actually I was mixing things up (at least twice).
When I wrote the paragraph above my concern was both reallocation *and*
deep copy. More precisely I thought the reallocation, triggered e.g. by
Vectors.Append, would not only cause the internal array to be copied,
but all items in the Vector to be deep-copied from the old array to the
newly allocated array.
Then I thought I was mistaken, and just like C's realloc() doesn't mess
with internal pointers pointing to outside of the reallocated area, the
Vector could do a mere shallow copy.
And now I have just had a look at GNAT FSF (v4.4) implementation, and
there is a normal array assignment, which I guess triggers an assignment
of each item, which in our case (record containing a Vector) triggers a
deep copy. Or am I wrong here?
So it seems a simple Vector.Append call might trigger a copy of the
entire S-expression, which makes a strong point for the linked-list,
doesn't it?
> I used Vector here because I thought it would be clearer what is
> happening, since it's an unbounded array. Iteration thus uses "for"
> loops and indexing to access the elements, similar to arrays; I
> thought this would be clearer to a beginner (in Ada). Lists and arrays
> are both sequences and do the same things, so either could be used.
Ok, I understand the motive.
And indeed, your implementation was the first I understood almost
completely, but I can't tell how much is due to your clarity intend and
how much is due to having already tried to write one.
Anyway, thanks for your efforts in pedagogy.
> OK, I misunderstood that bit. Making the definition of Atom public would be
> fine, then, allowing clients to create their own. You could also replace the
> definition of Atom with
>
> subtype Atom is Byte_Lists.Vector;
>
> which would simplify the implementation a bit.
I'm still wondering which is better between vector and array. I thought
a vector could be easily be turned into an array, hence my initial
choice of arrays, but it seems there is no such vector primitive in
A.18.2. Another tough choice...
> Yes, ideally we want a list of S_Expression. However, the language
> doesn't allow us to create that directly. I can't instantiate Vectors
> with S_Expression before I declare S_Expression, and I can't declare
> S_Expression until I've instantiated Vectors for lists.
OK, I understand the catch-22 problem here. I guess it will be the same
with linked lists instead of vectors.
Is there any other (perhaps more difficult for a beginner) way to
address that issue?
Thanks a lot for your help,
Natacha
next prev parent reply other threads:[~2010-08-19 8:09 UTC|newest]
Thread overview: 252+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-01 12:17 S-expression I/O in Ada Natacha Kerensikova
2010-08-01 12:53 ` Dmitry A. Kazakov
2010-08-01 17:35 ` Natacha Kerensikova
2010-08-01 18:49 ` Dmitry A. Kazakov
2010-08-01 20:06 ` Natacha Kerensikova
2010-08-01 21:13 ` Dmitry A. Kazakov
2010-08-02 7:17 ` Georg Bauhaus
2010-08-02 7:58 ` Dmitry A. Kazakov
2010-08-07 7:23 ` Natacha Kerensikova
2010-08-07 8:39 ` Dmitry A. Kazakov
2010-08-07 12:56 ` Natacha Kerensikova
2010-08-07 14:23 ` Dmitry A. Kazakov
2010-08-08 12:23 ` Natacha Kerensikova
2010-08-08 13:01 ` Dmitry A. Kazakov
2010-08-08 13:49 ` Natacha Kerensikova
2010-08-08 15:15 ` Dmitry A. Kazakov
2010-08-09 9:55 ` Natacha Kerensikova
2010-08-09 10:56 ` Dmitry A. Kazakov
2010-08-10 8:56 ` Natacha Kerensikova
2010-08-10 10:17 ` Georg Bauhaus
2010-08-10 10:36 ` Dmitry A. Kazakov
2010-08-10 12:06 ` Natacha Kerensikova
2010-08-10 15:46 ` Dmitry A. Kazakov
2010-08-10 21:22 ` Simon Wright
2010-08-11 7:37 ` Dmitry A. Kazakov
2010-08-11 17:32 ` Simon Wright
2010-08-11 17:53 ` Dmitry A. Kazakov
2010-08-11 9:43 ` Natacha Kerensikova
2010-08-11 10:37 ` Dmitry A. Kazakov
2010-08-11 11:38 ` Natacha Kerensikova
2010-08-11 12:58 ` Robert A Duff
2010-08-11 15:30 ` Natacha Kerensikova
2010-08-11 23:39 ` Randy Brukardt
2010-08-12 1:31 ` Robert A Duff
2010-08-12 8:53 ` Natacha Porté
2010-08-12 9:22 ` Georg Bauhaus
2010-08-13 9:43 ` Natacha Kerensikova
2010-08-10 21:56 ` Randy Brukardt
2010-08-09 15:40 ` Simon Wright
2010-08-09 16:35 ` Robert A Duff
2010-08-10 0:51 ` Randy Brukardt
2010-08-10 1:00 ` Jeffrey Carter
2010-08-10 21:36 ` Randy Brukardt
2010-08-10 22:24 ` Jeffrey Carter
2010-08-10 12:50 ` Robert A Duff
2010-08-10 22:06 ` Randy Brukardt
2010-08-09 18:37 ` Natacha Kerensikova
2010-08-09 19:10 ` Robert A Duff
2010-08-08 14:08 ` Duke Normandin
2010-08-08 15:34 ` Robert A Duff
2010-08-08 18:24 ` Dmitry A. Kazakov
2010-08-08 20:03 ` Robert A Duff
2010-08-08 20:39 ` Dmitry A. Kazakov
2010-08-08 21:08 ` Robert A Duff
2010-08-09 6:50 ` Dmitry A. Kazakov
2010-08-09 13:48 ` Robert A Duff
2010-08-09 14:38 ` Dmitry A. Kazakov
2010-08-09 15:14 ` Georg Bauhaus
2010-08-09 16:11 ` Dmitry A. Kazakov
2010-08-09 16:46 ` Georg Bauhaus
2010-08-09 17:05 ` Robert A Duff
2010-08-09 18:29 ` Georg Bauhaus
2010-08-09 19:18 ` Robert A Duff
2010-08-10 8:21 ` Georg Bauhaus
2010-08-09 20:40 ` Dmitry A. Kazakov
2010-08-09 22:21 ` Georg Bauhaus
2010-08-10 7:07 ` Dmitry A. Kazakov
2010-08-09 16:47 ` Robert A Duff
2010-08-09 19:59 ` Dmitry A. Kazakov
2010-08-09 21:34 ` Robert A Duff
2010-08-09 22:29 ` Jeffrey Carter
2010-08-10 7:48 ` Dmitry A. Kazakov
2010-08-09 21:54 ` _FrnchFrgg_
2010-08-09 22:32 ` Georg Bauhaus
2010-08-10 7:16 ` Dmitry A. Kazakov
2010-08-10 11:06 ` _FrnchFrgg_
2010-08-10 11:19 ` Dmitry A. Kazakov
2010-08-10 23:04 ` _FrnchFrgg_
2010-08-11 14:10 ` Dmitry A. Kazakov
2010-08-11 17:51 ` Structural unification (pattern matching) in Ada [was: Re: S-expression I/O in Ada] _FrnchFrgg_
2010-08-11 18:06 ` Dmitry A. Kazakov
2010-08-11 19:43 ` Robert A Duff
2010-08-11 20:26 ` (see below)
2010-08-11 21:21 ` Structural unification (pattern matching) in Ada Simon Wright
2010-08-12 12:43 ` Structural unification (pattern matching) in Ada [was: Re: S-expression I/O in Ada] _FrnchFrgg_
2010-08-10 1:06 ` S-expression I/O in Ada Randy Brukardt
2010-08-09 16:50 ` Robert A Duff
2010-08-09 18:32 ` Natacha Kerensikova
2010-08-09 19:06 ` Jeffrey Carter
2010-08-09 19:24 ` Robert A Duff
2010-08-09 19:35 ` (see below)
2010-08-09 17:00 ` Robert A Duff
2010-08-09 20:27 ` Dmitry A. Kazakov
2010-08-09 21:30 ` Robert A Duff
2010-08-10 1:17 ` Randy Brukardt
2010-08-10 6:48 ` Dmitry A. Kazakov
2010-08-10 21:42 ` Randy Brukardt
2010-08-11 8:02 ` Dmitry A. Kazakov
2010-08-11 23:18 ` Randy Brukardt
2010-08-12 6:20 ` Dmitry A. Kazakov
2010-08-12 20:56 ` Randy Brukardt
2010-08-13 6:56 ` Dmitry A. Kazakov
2010-08-14 0:52 ` Randy Brukardt
2010-08-09 18:55 ` Jeffrey Carter
2010-08-09 18:20 ` Natacha Kerensikova
2010-08-09 19:19 ` Robert A Duff
2010-08-07 15:38 ` Jeffrey Carter
2010-08-07 17:01 ` Natacha Kerensikova
2010-08-08 6:52 ` Jeffrey Carter
2010-08-08 13:11 ` Natacha Kerensikova
2010-08-08 15:24 ` Robert A Duff
2010-08-09 18:00 ` Natacha Kerensikova
2010-08-09 18:09 ` Robert A Duff
2010-08-08 20:34 ` Jeffrey Carter
2010-08-09 18:10 ` Natacha Kerensikova
2010-08-08 10:26 ` Simon Wright
2010-08-08 11:44 ` Dmitry A. Kazakov
2010-08-08 11:48 ` Dmitry A. Kazakov
2010-08-08 14:05 ` Natacha Kerensikova
2010-08-08 20:11 ` Jeffrey Carter
2010-08-14 1:02 ` Yannick Duchêne (Hibou57)
2010-08-14 9:53 ` Georg Bauhaus
2010-08-14 11:32 ` Natacha Kerensikova
2010-08-01 22:03 ` Simon Wright
2010-08-02 17:08 ` Pascal Obry
2010-08-02 19:08 ` Simon Wright
2010-08-01 16:01 ` Ludovic Brenta
2010-08-09 18:49 ` Ludovic Brenta
2010-08-09 19:59 ` Natacha Kerensikova
2010-08-10 0:11 ` Ludovic Brenta
2010-08-10 0:57 ` Jeffrey Carter
2010-08-10 6:47 ` Natacha Kerensikova
2010-08-10 18:13 ` Jeffrey Carter
2010-08-12 9:26 ` Natacha Kerensikova
2010-08-12 10:55 ` Ludovic Brenta
2010-08-12 12:16 ` Natacha Kerensikova
2010-08-12 12:46 ` Ludovic Brenta
2010-08-12 13:23 ` Natacha Kerensikova
2010-08-12 16:19 ` Ludovic Brenta
2010-08-12 17:17 ` Natacha Kerensikova
2010-08-12 18:51 ` Jeffrey Carter
2010-08-13 9:32 ` Natacha Kerensikova
2010-08-13 15:52 ` Ludovic Brenta
2010-08-13 22:53 ` Jeffrey R. Carter
2010-08-14 11:10 ` Natacha Kerensikova
2010-08-10 15:48 ` Ludovic Brenta
2010-08-10 15:59 ` Georg Bauhaus
2010-08-12 7:53 ` Ludovic Brenta
2010-08-12 18:55 ` Jeffrey Carter
2010-08-12 19:59 ` Ludovic Brenta
2010-08-12 20:23 ` Natacha Kerensikova
2010-08-12 20:45 ` Ludovic Brenta
2010-08-13 8:24 ` Natacha Kerensikova
2010-08-13 9:08 ` Ludovic Brenta
2010-08-14 10:27 ` Natacha Kerensikova
2010-08-14 11:11 ` Ludovic Brenta
2010-08-14 12:17 ` Natasha Kerensikova
2010-08-14 13:13 ` Ludovic Brenta
2010-08-14 13:33 ` Yannick Duchêne (Hibou57)
2010-08-12 22:25 ` Jeffrey R. Carter
2010-08-13 9:10 ` Natacha Kerensikova
2010-08-13 9:51 ` Dmitry A. Kazakov
2010-08-14 10:36 ` Natacha Kerensikova
2010-08-14 10:57 ` Dmitry A. Kazakov
2010-08-13 19:23 ` Jeffrey Carter
2010-08-13 19:42 ` Dmitry A. Kazakov
2010-08-13 20:44 ` Yannick Duchêne (Hibou57)
2010-08-14 0:57 ` Randy Brukardt
2010-08-14 10:47 ` Natacha Kerensikova
2010-08-13 19:36 ` Simon Wright
2010-08-12 20:11 ` Natacha Kerensikova
2010-08-12 20:22 ` Ludovic Brenta
2010-08-01 18:25 ` Jeffrey Carter
2010-08-01 19:43 ` Natacha Kerensikova
2010-08-01 19:53 ` Ludovic Brenta
2010-08-01 20:00 ` Dmitry A. Kazakov
2010-08-01 20:03 ` Jeffrey Carter
2010-08-01 20:34 ` Georg Bauhaus
2010-08-01 20:44 ` Georg Bauhaus
2010-08-01 21:01 ` anon
2010-08-12 23:26 ` Shark8
2010-08-13 2:31 ` Shark8
2010-08-13 8:56 ` Natacha Kerensikova
2010-08-13 10:30 ` Georg Bauhaus
2010-08-13 15:58 ` Shark8
2010-08-13 21:48 ` Shark8
2010-08-14 11:02 ` Natacha Kerensikova
2010-08-17 17:01 ` Natasha Kerensikova
2010-08-17 19:00 ` Jeffrey Carter
2010-08-18 10:49 ` Natasha Kerensikova
2010-08-18 11:14 ` Ludovic Brenta
2010-08-18 11:59 ` Natasha Kerensikova
2010-08-18 12:31 ` Ludovic Brenta
2010-08-18 13:16 ` J-P. Rosen
2010-08-18 13:55 ` Natasha Kerensikova
2010-08-18 14:40 ` J-P. Rosen
2010-08-20 20:50 ` Yannick Duchêne (Hibou57)
2010-08-18 15:07 ` Ludovic Brenta
2010-08-19 7:42 ` Natasha Kerensikova
2010-08-18 12:51 ` Georg Bauhaus
2010-08-18 13:24 ` Natasha Kerensikova
2010-08-18 14:40 ` Georg Bauhaus
2010-08-18 23:50 ` Randy Brukardt
2010-08-18 11:22 ` Georg Bauhaus
2010-08-18 12:02 ` Natasha Kerensikova
2010-08-20 21:04 ` Yannick Duchêne (Hibou57)
2010-08-22 10:21 ` Natasha Kerensikova
2010-08-22 10:28 ` Simon Wright
2010-08-22 17:13 ` Jeffrey Carter
2010-08-22 14:06 ` Dmitry A. Kazakov
2010-08-21 19:36 ` Yannick Duchêne (Hibou57)
2010-08-18 18:08 ` Jeffrey Carter
2010-08-19 8:09 ` Natasha Kerensikova [this message]
2010-08-19 10:16 ` Natasha Kerensikova
2010-08-19 10:42 ` Dmitry A. Kazakov
2010-08-22 10:24 ` Natasha Kerensikova
2010-08-22 14:10 ` Dmitry A. Kazakov
2010-08-19 18:07 ` Jeffrey Carter
2010-08-22 10:43 ` Natasha Kerensikova
2010-08-22 17:17 ` Jeffrey Carter
2010-08-19 17:59 ` Jeffrey Carter
2010-08-22 10:45 ` Natasha Kerensikova
2010-08-22 17:20 ` Jeffrey Carter
2010-08-24 11:41 ` Natasha Kerensikova
2010-08-25 1:56 ` Jeffrey Carter
2010-08-25 12:18 ` Natasha Kerensikova
2010-08-25 14:07 ` Jeffrey Carter
2010-08-25 8:06 ` Georg Bauhaus
2010-08-25 13:27 ` Natasha Kerensikova
2010-08-25 18:55 ` Simon Wright
2010-08-25 19:19 ` Georg Bauhaus
2010-08-25 19:23 ` Georg Bauhaus
2010-08-25 22:38 ` Simon Wright
2010-08-25 23:55 ` Georg Bauhaus
2010-08-27 13:19 ` Natasha Kerensikova
2010-08-27 14:57 ` Georg Bauhaus
2010-08-29 10:45 ` Natasha Kerensikova
2010-08-29 13:10 ` Simon Wright
2010-08-29 14:21 ` Natasha Kerensikova
2010-08-29 14:30 ` Niklas Holsti
2010-08-29 13:23 ` Robert A Duff
2010-08-29 13:57 ` Jeffrey Carter
2010-08-29 14:18 ` Britt Snodgrass
2010-08-29 14:29 ` Natasha Kerensikova
2010-08-29 15:12 ` Robert A Duff
2010-09-03 21:52 ` Randy Brukardt
2010-08-29 13:56 ` Jeffrey Carter
2010-08-29 14:34 ` Natasha Kerensikova
2010-08-29 14:55 ` Dmitry A. Kazakov
2010-08-29 15:25 ` Robert A Duff
2010-08-29 18:50 ` Georg Bauhaus
2010-08-29 21:43 ` Simon Wright
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