73ef4ff3
 Hu Chunming
提交三方库
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[#alphanum]
[section alphanum]
[h1 Synopsis]
struct alphanum;
This is a [link parser parser].
[h1 Description]
It accepts one character in the range `a-z`, `A-Z` or `0-9`. The
result of the parser is the accepted character.
[h1 Header]
#include <boost/metaparse/alphanum.hpp>
[h1 Expression semantics]
The following are equivalent:
alphanum
one_of<digit, letter>
[h1 Example]
#include <boost/metaparse/alphanum.hpp>
#include <boost/metaparse/start.hpp>
#include <boost/metaparse/string.hpp>
#include <boost/metaparse/is_error.hpp>
#include <boost/metaparse/get_result.hpp>
using namespace boost::metaparse;
static_assert(
!is_error<alphanum::apply<BOOST_METAPARSE_STRING("0"), start>>::type::value,
"alphanum should accept a digit"
);
static_assert(
!is_error<alphanum::apply<BOOST_METAPARSE_STRING("x"), start>>::type::value,
"alphanum should accept a character"
);
static_assert(
get_result<
alphanum::apply<BOOST_METAPARSE_STRING("x"), start>
>::type::value == 'x',
"the result of parsing should be the character value"
);
static_assert(
is_error<alphanum::apply<BOOST_METAPARSE_STRING(","), start>>::type::value,
"alphanum should reject a comma"
);
[endsect]
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