Re: [cpp-netlib-devel] HTTP Server - Request query

[Nelson, E. - 2 <eri...@ba...>]

> On Wed, Jan 12, 2011 at 12:26 AM, David Hite <dav...@gm...>
> wrote:
> > Hello,
> > I am trying to parse the incoming query in a request to the
> synchronous
> > server. I see that there is a "query" method on the HTTP Normal
> Client
> > Request but not the Pod Server Request. I can't find any example of
> the
> > server request query parameters.
> >
> > Is there a simple way to pull out the "?" query portion of the uri?
> >
> > I am able to get the destination(request) method to work and could
do
> some
> > string parsing but I figured there is a better way...
> >

We use something like this in a header

********************************************
#include "boost/spirit/include/qi.hpp"
#include <string>
#include <utility>

template <typename Iterator, typename map_type>
struct key_value_sequence : boost::spirit::qi::grammar<Iterator,
map_type()>
{
   key_value_sequence() : key_value_sequence::base_type(query)
   {
      query =  pair >> *((boost::spirit::qi::lit(';') | '&') >> pair);
      pair  =  key >> -('=' >> value);
      key   =  boost::spirit::qi::char_("a-zA-Z_0-9%+") >>
*boost::spirit::qi::char_("a-zA-Z_0-9%+");
      value = +boost::spirit::qi::char_("a-zA-Z_0-9%+");
   }

   boost::spirit::qi::rule<Iterator, map_type()> query;
   boost::spirit::qi::rule<Iterator, std::pair<std::string,
std::string>()> pair;
   boost::spirit::qi::rule<Iterator, std::string()> key, value;
};

template<typename map_type>
inline map_type& parse_http_query(const std::string& uri, map_type&
output)
{
   std::string new_uri(uri);  // this should go away when qi can parse
const iterators
   key_value_sequence<std::string::iterator, map_type> p;
   const size_t query_pos = new_uri.find('?');
   std::string::iterator begin = std::string::npos == query_pos ?
new_uri.end() : new_uri.begin() + query_pos + 1;
   std::string::iterator end = new_uri.end();
   if (!boost::spirit::qi::parse(begin, end, p, output))
   {
      // throw an error here if non-parsing is considered erroneous
   }
   return output;
}
**********************************************

Used like this

**********************************************************
string object;
const size_t query_pos = request.uri.find('?');
if(not request.uri.empty()) // if we have a uri
{
   object.assign(*request.uri.begin() == '/' ? ++request.uri.begin() :
request.uri.begin(), std::string::npos == query_pos ? request.uri.end()
: request.uri.begin() + query_pos);
}

std::map<std::string, std::string> args;
parse_http_query(request.uri, args);

**************************************************


I think it's mostly derived from some Spirit examples somebody found
somewhere.

Erik

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