metaparse/doc/get_position.qbk
2015-07-19 09:53:35 +02:00

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[#get_position]
[section get_position]
[h1 Synopsis]
template <class D>
struct get_position;
This is a [link lazy_metafunction lazy template metafunction].
[table Arguments
[[Name] [Type]]
[[`D`] [[link accept accept] or [link reject reject] value]]
]
[h1 Description]
Returns the source position information of a parsing result.
[h1 Header]
#include <boost/metaparse/get_position.hpp>
[h1 Example]
#include <boost/metaparse/get_position.hpp>
#include <boost/metaparse/start.hpp>
#include <boost/metaparse/accept.hpp>
#include <boost/metaparse/reject.hpp>
#include <boost/metaparse/string.hpp>
#include <boost/metaparse/define_error.hpp>
#include <type_traits>
using namespace boost::metaparse;
BOOST_METAPARSE_DEFINE_ERROR(sample_error, "Sample error message");
struct returns_reject
{
using type = reject<sample_error, start>;
};
static_assert(
std::is_same<
start,
get_position<reject<sample_error, start>>::type
>::type::value,
"It should return the position of a reject"
);
static_assert(
std::is_same<
start,
get_position<
accept<sample_error, BOOST_METAPARSE_STRING("foo"), start>
>::type
>::type::value,
"It should return the position of an accept"
);
static_assert(
std::is_same<start, get_position<returns_reject>::type>::type::value,
"It should support lazy evaluation"
);
[endsect]