1[#foldl_reject_incomplete1] 2[section foldl_reject_incomplete1] 3 4[h1 Synopsis] 5 6 template <class P, class State, class ForwardOp> 7 struct foldl_reject_incomplete1; 8 9This is a [link parser_combinator parser combinator]. 10 11[table Arguments 12 [[Name] [Type]] 13 [[`P`] [[link parser parser]]] 14 [[`State`] [[link metaprogramming_value template metaprogramming value]]] 15 [[`ForwardOp`] [[link metafunction_class template metafunction class] taking two arguments]] 16] 17 18[h1 Description] 19 20The same as [link foldl1 `foldl1`], but once `P` rejects the input, 21`foldl_reject_incomplete1` checks if `P` consumes any characters before 22rejecting the input. If so, `foldl_reject_incomplete1` rejects the input with 23the same error message this last application of `P` returned. Otherwise 24`foldl_reject_incomplete1` accepts the input and gives the same result as 25[link foldl1 `foldl1`]. 26 27[h1 Header] 28 29 #include <boost/metaparse/foldl_reject_incomplete1.hpp> 30 31[h1 Expression semantics] 32 33For any `p` parser, `t` class, `f` metafunction class taking two arguments, 34`s` compile-time string and `pos` source position 35 36 foldl_reject_incomplete1<p, t, f>::apply<s, pos> 37 38is equivalent to 39 40 first_of<foldl1<p, t, f>, fail_at_first_char_expected<p> >::apply<s, pos> 41 42[h1 Example] 43 44 #include <boost/metaparse/foldl_reject_incomplete1.hpp> 45 #include <boost/metaparse/lit_c.hpp> 46 #include <boost/metaparse/last_of.hpp> 47 #include <boost/metaparse/token.hpp> 48 #include <boost/metaparse/int_.hpp> 49 #include <boost/metaparse/string.hpp> 50 #include <boost/metaparse/start.hpp> 51 #include <boost/metaparse/get_result.hpp> 52 #include <boost/metaparse/is_error.hpp> 53 54 #include <boost/mpl/lambda.hpp> 55 #include <boost/mpl/plus.hpp> 56 #include <boost/mpl/int.hpp> 57 58 using namespace boost::metaparse; 59 60 using int_token = token<int_>; 61 using plus_token = token<lit_c<'+'>>; 62 using plus_int = last_of<plus_token, int_token>; 63 using sum_op = 64 boost::mpl::lambda<boost::mpl::plus<boost::mpl::_1, boost::mpl::_2>>::type; 65 66 using ints = foldl_reject_incomplete1<plus_int, boost::mpl::int_<11>, sum_op>; 67 68 static_assert( 69 get_result< 70 ints::apply<BOOST_METAPARSE_STRING("+ 13 + 3 + 21"), start> 71 >::type::value == 48, 72 "ints should sum the numbers" 73 ); 74 75 static_assert( 76 is_error< 77 ints::apply<BOOST_METAPARSE_STRING("+ 13 + 3 +"), start> 78 >::type::value, 79 "when the last number is missing, it should be an error" 80 ); 81 82 static_assert( 83 is_error<ints::apply<BOOST_METAPARSE_STRING(""), start>>::type::value, 84 "when no numbers are provided, it should be an error" 85 ); 86 87[endsect] 88 89