metaparse/doc/space.qbk
2015-10-20 12:22:15 +09:00

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[#space]
[section space]
[h1 Synopsis]
struct space;
This is a [link parser parser].
[h1 Description]
`space` accepts one white space character. The result of parsing is the parsed
character.
[h1 Header]
#include <boost/metaparse/space.hpp>
[h1 Expression semantics]
The following are equivalent:
space
accept_when<one_char, util::is_whitespace<>, errors::whitespace_expected>
[h1 Example]
#include <boost/metaparse/space.hpp>
#include <boost/metaparse/start.hpp>
#include <boost/metaparse/string.hpp>
#include <boost/metaparse/is_error.hpp>
#include <boost/metaparse/get_remaining.hpp>
#include <type_traits>
using namespace boost::metaparse;
static_assert(
std::is_same<
BOOST_METAPARSE_STRING(" foo"),
get_remaining<space::apply<BOOST_METAPARSE_STRING(" foo"), start>>::type
>::type::value,
"it should consume the first space of the input"
);
static_assert(
is_error<space::apply<BOOST_METAPARSE_STRING("x"), start>>::type::value,
"it should return an error when the input does not begin with a whitespace"
);
[endsect]