libs/spirit/doc/x3/tutorial/num_list2.qbk
[/==============================================================================
Copyright (C) 2001-2015 Joel de Guzman
Copyright (C) 2001-2011 Hartmut Kaiser
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
===============================================================================/]
[section Number List - stuffing numbers into a std::vector]
This sample demonstrates a parser for a comma separated list of numbers and
using a semantic action to collect the numbers into a `std::vector`.
template <typename Iterator>
bool parse_numbers(Iterator first, Iterator last, std::vector<double>& v)
{
using x3::double_;
using x3::phrase_parse;
using x3::_attr;
using ascii::space;
auto push_back = [&](auto& ctx){ v.push_back(_attr(ctx)); };
bool r = phrase_parse(first, last,
// Begin grammar
(
double_[push_back]
>> *(',' >> double_[push_back])
)
,
// End grammar
space);
if (first != last) // fail if we did not get a full match
return false;
return r;
}
The full cpp file for this example can be found here:
[@../../../example/x3/num_list/num_list2.cpp num_list2.cpp]
This, again, is the same parser as before. This time, instead of summing up the
numbers, we stuff them in a `std::vector`.
[&](auto& ctx){ v.push_back(_attr(ctx)); }
[endsect]
