Reputation: 393769
question asked: Spirit-general list
Hello all,
I'm not sure if my subject is correct, but the testcode will probably show what I want to achieve.
I'm trying to parse things like:
I have a minimal testcase below. I don't understand why this doesn't work. It's probably me making a mistake but I don't see it.
Using: Compiler: gcc 4.6 Boost: current trunk
I use the following compile line:
g++ -o main -L/usr/src/boost-trunk/stage/lib -I/usr/src/boost-trunk -g -Werror -Wall -std=c++0x -DBOOST_SPIRIT_USE_PHOENIX_V3 main.cpp
#include <iostream>
#include <string>
#define BOOST_SPIRIT_UNICODE
#include <boost/cstdint.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/phoenix/phoenix.hpp>
typedef boost::uint32_t uchar; // Unicode codepoint
namespace qi = boost::spirit::qi;
int main(int argc, char **argv) {
// Input
std::string input = "%3C";
std::string::const_iterator begin = input.begin();
std::string::const_iterator end = input.end();
using qi::xdigit;
using qi::_1;
using qi::_2;
using qi::_val;
qi::rule<std::string::const_iterator, uchar()> pchar =
('%' > xdigit > xdigit) [_val = (_1 << 4) + _2];
std::string result;
bool r = qi::parse(begin, end, pchar, result);
if (r && begin == end) {
std::cout << "Output: " << result << std::endl;
std::cout << "Expected: < (LESS-THAN SIGN)" << std::endl;
} else {
std::cerr << "Error" << std::endl;
return 1;
}
return 0;
}
Regards,
Matthijs Möhlmann
Upvotes: 4
Views: 708
Reputation: 393769
qi::xdigit
does not do what you think it does: it returns the raw character (i.e. '0'
, not 0x00
).
You could leverage qi::uint_parser
to your advantage, making your parse much simpler as a bonus:
typedef qi::uint_parser<uchar, 16, 2, 2> xuchar;
Here is a fixed up sample:
#include <iostream>
#include <string>
#define BOOST_SPIRIT_UNICODE
#include <boost/cstdint.hpp>
#include <boost/spirit/include/qi.hpp>
typedef boost::uint32_t uchar; // Unicode codepoint
namespace qi = boost::spirit::qi;
typedef qi::uint_parser<uchar, 16, 2, 2> xuchar;
const static xuchar xuchar_ = xuchar();
int main(int argc, char **argv) {
// Input
std::string input = "%3C";
std::string::const_iterator begin = input.begin();
std::string::const_iterator end = input.end();
qi::rule<std::string::const_iterator, uchar()> pchar = '%' > xuchar_;
uchar result;
bool r = qi::parse(begin, end, pchar, result);
if (r && begin == end) {
std::cout << "Output: " << result << std::endl;
std::cout << "Expected: < (LESS-THAN SIGN)" << std::endl;
} else {
std::cerr << "Error" << std::endl;
return 1;
}
return 0;
}
Output:
Output: 60
Expected: < (LESS-THAN SIGN)
'<' is indeed ASCII 60
Upvotes: 2