I'm trying to parse a file and have the data copied into a vector within a class object. I've taken the employee example and modified it to what I'm trying to do. The file being parsed looks like this (but more lines) ...
1 0.2 0.3 0.4
I've added a vector to struct employee and am getting assertion failures on the phrase_parse line.
static assertion failed: Attribute does not have the expected size.
static_assert(
^
I'm kind of thinking the expected size has something to do with the vector. Thoughts on where I'm going wrong?
namespace client {
namespace ast {
struct employee
{
int id;
std::vector<double> coords;
};
using boost::fusion::operator<<;
}}
BOOST_FUSION_ADAPT_STRUCT(
client::ast::employee,
(int, id)
(std::vector<double>, coords)
)
namespace client
{
namespace parser
{
namespace x3 = boost::spirit::x3;
namespace ascii = boost::spirit::x3::ascii;
using x3::int_;
using x3::double_;
x3::rule<class employee, ast::employee> const employee = "employee";
auto const employee_def =
int_ >> double_ >> double_ >> double_;
BOOST_SPIRIT_DEFINE(employee)
}
}
int main()
{
using boost::spirit::x3::ascii::space;
using client::parser::employee;
string fil("test-file.in");
mapped_file_source map(fil);
istringstream iss(map.data());
map.close();
client::ast::employee emp;
boost::spirit::istream_iterator iter(iss >> noskipws), eof;
phrase_parse(iter, eof, employee, space, emp);
// failure on above line
}
According to the documentation, double_ >> double_ >> double_
synthesizes a Fusion sequence of double, double, double (so fusion::tuple<double, double, double>
or fusion::list<double, double, double>
etc).
You want a vector, so you need a repeating parser (operator)
repeat(3) [double_]
operator *
) or plus (operator +
) are interesting (but unbounded)operator %
) is also unbounded but accepts delimiters (e.g. double_ % ','
In this case I'd go the other way: use a proper AST for the grammar:
struct coord {
double x,y,z;
};
struct employee
{
int id;
coord coords;
};
Adapting them is simpler than the old fashioned method you used:
BOOST_FUSION_ADAPT_STRUCT(client::ast::coord, x, y, z)
BOOST_FUSION_ADAPT_STRUCT(client::ast::employee, id, coords)
The parser is a clean
auto const coord_def = double_ >> double_ >> double_;
auto const employee_def = int_ >> coord;
Full demo:
#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/include/support_istream_iterator.hpp>
#include <boost/fusion/adapted/struct.hpp>
#include <iostream>
namespace client {
namespace ast {
struct coord {
double x,y,z;
};
struct employee
{
int id;
coord coords;
};
using boost::fusion::operator<<;
}}
BOOST_FUSION_ADAPT_STRUCT(client::ast::coord, x, y, z)
BOOST_FUSION_ADAPT_STRUCT(client::ast::employee, id, coords)
namespace client
{
namespace parser
{
namespace x3 = boost::spirit::x3;
namespace ascii = boost::spirit::x3::ascii;
using x3::int_;
using x3::double_;
x3::rule<class employee, ast::coord> const coord = "coord";
x3::rule<class employee, ast::employee> const employee = "employee";
auto const coord_def = double_ >> double_ >> double_;
auto const employee_def = int_ >> coord;
BOOST_SPIRIT_DEFINE(employee, coord);
}
}
int main()
{
using boost::spirit::x3::ascii::space;
using client::parser::employee;
std::istringstream iss("1 0.2 0.3 0.4");
client::ast::employee emp;
boost::spirit::istream_iterator iter(iss >> std::noskipws), eof;
bool ok = phrase_parse(iter, eof, employee, space, emp);
if (ok)
std::cout << "parsed: "
<< emp.id << " "
<< emp.coords.x << " "
<< emp.coords.y << " "
<< emp.coords.z << "\n";
}