Boost :: spirit :: qi :: parse & # 8594; No result
Consider the following code:
namespace qi = boost::spirit::qi;
typedef qi::rule<
std::string::const_iterator
> rule_type;
rule_type value_rule = +qi::char_ - ( '[' | qi::eoi );
std::string input( "Hello World" );
std::string value0, value1;
bool b0 = qi::parse( input.begin( ),
input.end( ),
value_rule,
value0 );
bool b1 = qi::parse( input.begin( ),
input.end( ),
+qi::char_ - ( '[' | qi::eoi ),
value1 );
Result:
b0 = true
b1 = true
value0 = ""
value1 = "Hello World"
I am confused why the result is different. What is the correct type definition for qi :: rule to get the same result?
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1 answer
You forgot to make a rule to declare its public attribute type:
typedef qi::rule<std::string::const_iterator, std::string()> rule_type;
#include <boost/spirit/include/qi.hpp>
namespace qi = boost::spirit::qi;
int main()
{
std::string const input( "Hello World" );
{
typedef qi::rule<std::string::const_iterator, std::string()> rule_type;
rule_type value_rule = +qi::char_ - ( '[' | qi::eoi );
std::string value;
bool ok = qi::parse( input.begin( ),
input.end( ),
value_rule,
value );
std::cout << std::boolalpha << ok << "\t" << value << "\n";
}
{
std::string value;
bool ok = qi::parse( input.begin( ),
input.end( ),
+qi::char_ - ( '[' | qi::eoi ),
value );
std::cout << std::boolalpha << ok << "\t" << value << "\n";
}
}
Output
true Hello World
true Hello World
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