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

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[#entire_input]
[section entire_input]
[h1 Synopsis]
template <class P, class Msg = error::end_of_input_expected>
struct entire_input;
This is a [link parser_combinator parser combinator].
[table Arguments
[[Name] [Type]]
[[`P`] [[link parser parser]]]
[[`Msg`] [[link parsing_error_message parsing error message]]]
]
[h1 Description]
It parses the input using `P` and checks if it consumes the entire input. If `P`
fails or doesn't consume the entire input, `entire_input` fails. Otherwise
`entire_input` returns the result of `P`. When `P` does not consume the entire
input, the error message returned by `entire_input` is `Msg`.
[h1 Header]
#include <boost/metaparse/entire_input.hpp>
[h1 Expression semantics]
For any `p` parser and `e` parsing error message the following are equivalent
entire_input<p, e>
first_of<
p,
change_error_message<empty</* some metaprogramming value */>, e>
>
[h1 Example]
#include <boost/metaparse/entire_input.hpp>
#include <boost/metaparse/int_.hpp>
#include <boost/metaparse/string.hpp>
#include <boost/metaparse/start.hpp>
#include <boost/metaparse/get_result.hpp>
#include <boost/metaparse/get_message.hpp>
#include <boost/metaparse/define_error.hpp>
using namespace boost::metaparse;
BOOST_METAPARSE_DEFINE_ERROR(extra_chars_at_end, "Extra chars at end");
using int_parser = entire_input<int_, extra_chars_at_end>;
static_assert(
get_result<
int_parser::apply<BOOST_METAPARSE_STRING("1113"), start>
>::type::value == 1113,
"it should parse the input if it contains only an integer"
);
static_assert(
std::is_same<
get_message<
int_parser::apply<BOOST_METAPARSE_STRING("1113mm"), start>
>::type,
extra_chars_at_end
>::type::value,
"it should return the specified error message when there are extra characters"
);
[endsect]