On Thu, Sep 5, 2013 at 8:42 PM, Michael Powell wrote:

Oh yeah, and then I am adapting it into a struct:

BOOST_FUSION_ADAPT_STRUCT( dchem::drivers::nmea::basic_nmea_message_t, (std::string, m_message) (int, m_checksum) )

Or at least I'd like to. I've got the general framework understood from the employee-examples.

Thanks again.

I came up with something like this, but I may be completely off the mark: qi::rule r_message; qi::rule r_checksum; qi::rule r_start; using qi::char_; using qi::lit; using qi::hex; r_message %= +(char_); r_checksum %= hex >> hex; r_start %= lit('$') >> r_message >> lit('*') >> r_checksum >> lit('\r') >> lit('\n'); The I/O transport itself will handle wrapping/unwrapping when it sees '$' and the terminus "\r\n" and pass that along to the parser for handling. What I am uncertain about is how the rules consume the message and engage with the adaptation. Thank ye...

On Thu, Sep 5, 2013 at 8:39 PM, Michael Powell wrote:

...

Hello,

I'm digging into a qi rule for GPS NMEA and want to approach it as a kind of 2-pass parser. First pass to extract the message and hex-formatted checksum. Next pass to parse out the actual messages from the message.

I believe I comprehend how to go about the second pass. For the first pass, I want to parse $XYZ*HH\r\n.

That's the literal '$', and everything between there and the literal '*', followed by the two hex characters, as a complete field, followed by the terminal CR+LF.

How do I express the "all characters excluding '*'" for the NMEA message? Then the hex field?

Thanks...

Regards,

Michael Powell

On Thu, Sep 5, 2013 at 8:54 PM, Michael Caisse wrote:

On 09/05/2013 06:42 PM, Michael Powell wrote:

...

Oh yeah, and then I am adapting it into a struct:

BOOST_FUSION_ADAPT_STRUCT( dchem::drivers::nmea::basic_nmea_message_t, (std::string, m_message) (int, m_checksum) )

Or at least I'd like to. I've got the general framework understood from the employee-examples.

Thanks again.

On Thu, Sep 5, 2013 at 8:39 PM, Michael Powell wrote:

...

Hello,

I'm digging into a qi rule for GPS NMEA and want to approach it as a kind of 2-pass parser. First pass to extract the message and hex-formatted checksum. Next pass to parse out the actual messages from the message.

I believe I comprehend how to go about the second pass. For the first pass, I want to parse $XYZ*HH\r\n.

That's the literal '$', and everything between there and the literal '*', followed by the two hex characters, as a complete field, followed by the terminal CR+LF.

How do I express the "all characters excluding '*'" for the NMEA message? Then the hex field?

Hi Michael -

Parsing NMEA is about as easy as you have described in english.

rule = lit('$') >> ~char_('*') >> lit('$') >> hex >> lit("\r\n");

Pretty straightforward. How about the wrinkle of enforcing the NMEA 2-hex-digit checksum?

That should parse into the fusion adapted sequence you have described.

hth - michael

-- Michael Caisse ciere consulting ciere.com _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

On Thu, Sep 5, 2013 at 9:27 PM, Michael Caisse wrote:

On 09/05/2013 07:00 PM, Michael Powell wrote:

...

On Thu, Sep 5, 2013 at 8:54 PM, Michael Caisse wrote:

...

...

Hi Michael -

Parsing NMEA is about as easy as you have described in english.

rule = lit('$') >> ~char_('*') >> lit('$') >> hex >> lit("\r\n");

Pretty straightforward. How about the wrinkle of enforcing the NMEA 2-hex-digit checksum?

It ends up that the Spirit numeric parser is customizable. Simply create the parser you want. For example:

qi::uint_parser< unsigned, 16, 2, 2 > nmea_hex_p;

creates a parser that will synthesize unsigned values that are parsed as base 16 and must have exactly 2 digits.

rule >> lit('$') >> ~char_('*') >> '*' >> nmea_hex_p >> "\r\n";

Well, whaddaya know. Poifect! Thanks!

michael

-- Michael Caisse ciere consulting ciere.com _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

On 09/05/2013 07:13 PM, Agustín K-ballo Bergé wrote:

On 05/09/2013 10:54 p.m., Michael Caisse wrote:

...

Parsing NMEA is about as easy as you have described in english.

rule = lit('$') >> ~char_('*') >> lit('$') >> hex >> lit("\r\n");

There should be a `>> '*'` right after `~char_('*')` to consume that '*'.

Regards,

Whoops. K-ballo is correct of course. I got a little hasty. The second lit('$') should be lit('*') or just '*'. -- Michael Caisse ciere consulting ciere.com