73ef4ff3
 Hu Chunming
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[#token]
[section token]
[h1 Synopsis]
template <class P>
struct token;
This is a [link parser_combinator parser combinator].
[table Arguments
[[Name] [Type]]
[[`P`] [[link parser parser]]]
]
[h1 Description]
`token` parses the input using `P` when it succeeds, `token` consumes all
whitespaces afterwards. The result of parsing is the result of `P`.
[h1 Header]
#include <boost/metaparse/token.hpp>
[h1 Expression semantics]
For any `p` parser the following are equivalent:
token<p>
first_of<p, spaces>
[h1 Example]
#include <boost/metaparse/token.hpp>
#include <boost/metaparse/int_.hpp>
#include <boost/metaparse/start.hpp>
#include <boost/metaparse/get_result.hpp>
#include <boost/metaparse/get_remaining.hpp>
#include <boost/metaparse/is_error.hpp>
#include <boost/metaparse/string.hpp>
#include <type_traits>
using namespace boost::metaparse;
using int_token = token<int_>;
static_assert(
get_result<
int_token::apply<BOOST_METAPARSE_STRING("13 "), start>
>::type::value,
"the result of int_token is the number"
);
static_assert(
std::is_same<
BOOST_METAPARSE_STRING(""),
get_remaining<int_token::apply<BOOST_METAPARSE_STRING("13 "), start>>::type
>::type::value,
"token consumes whitespaces after the number"
);
static_assert(
get_result<
int_token::apply<BOOST_METAPARSE_STRING("13"), start>
>::type::value,
"whitespaces after the number are optional"
);
static_assert(
is_error<int_token::apply<BOOST_METAPARSE_STRING("foo"), start>>::type::value,
"when there is no number, token fails"
);
[endsect]
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