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Subject: Re: [Boost-users] [Spirit][karma] Generating Pascal string like output
From: Olaf Meeuwissen (olaf.meeuwissen_at_[hidden])
Date: 2012-01-23 04:09:41

TONGARI <tongari95_at_[hidden]> writes:

> 2012/1/23 Olaf Meeuwissen <olaf.meeuwissen_at_[hidden]>
> Hi all,
> While I had no trouble getting the parsing part for this to work, I'm
> stuck on the generator part. Specifically, I'm stuck on getting the
> size into the output.
> The goal is a rule that takes a std::vector<byte> and outputs it in such
> a way that it is preceded by its size (in a custom encoding) and padded
> by zeroes to align on a four byte boundary.
> I want to reuse this rule in several other rules and prefer to break it
> up into smaller pieces. A minimalistic example of what I have come up
> with so far is attached. What I can't seem figure out how to get at and
> store the vector's size in pascal_string_size_. There also seem to be
> problems with refering to the stored size_ in pascal_string_payload_ and
> pascal_string_padding_ that I don't understand.
> o Use phoenix::size to extrac the size
> o Use karma::embed(*) to feed in the size
> o Use local variable to store the size
> o Use inherited attribute to pass the size
> Full code attached.
> =footnotes=
> (*) A component made by me, you can find it here:
> boost-jamboree-spirit. As an alternative, you can search "no_attr" on Spirit ML.

Hmm, karma::embed seems to require Boost > 1.46.1. At this point, that
is not an option for me :-(

  $ git clone boost-jamboree-spirit
  $ g++ -Iboost-jamboree-spirit -o pascal-string pascal-string.cpp
  In file included from /usr/include/boost/spirit/home/support/make_component.hpp:17:0,
                   from /usr/include/boost/spirit/home/support/meta_compiler.hpp:18,
                   from /usr/include/boost/spirit/home/support/terminal.hpp:18,
                   from boost-jamboree-spirit/boost/spirit/home/support/common_terminals.hpp:15,
                   from /usr/include/boost/spirit/home/karma/char/char.hpp:14,
                   from /usr/include/boost/spirit/home/karma/char.hpp:13,
                   from /usr/include/boost/spirit/home/karma.hpp:13,
                   from /usr/include/boost/spirit/include/karma.hpp:16,
                   from pascal-string.cpp:5:
  boost-jamboree-spirit/boost/spirit/home/support/modify.hpp:15:93: fatal error: boost/spirit/include/phoenix_limits.hpp: No such file or directory

The phoenix::size and inherited attribute where two helpful cluebats,
though. With those (and fixing some of the stupidities in my original
code) I've been able to come close but I always miss the first byte in
the vector. Any ideas why and how to fix that?

Note, I am "stuck" with Boost 1.46.1 for the time being.

Thanks in advance

Olaf Meeuwissen, LPIC-2           FLOSS Engineer -- AVASYS CORPORATION
FSF Associate Member #1962               Help support software freedom

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