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- [/==============================================================================
- 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 Redux - list syntax]
- So far, we've been using the syntax:
- double_ >> *(',' >> double_)
- to parse a comma-delimited list of numbers. Such lists are common in parsing and
- Spirit provides a simpler shortcut for them. The expression above can be
- simplified to:
- double_ % ','
- read as: a list of doubles separated by `','`.
- This sample, again a variation of our previous example, demonstrates just that:
- 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] % ','
- )
- ,
- // 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_list3.cpp num_list3.cpp]
- [endsect]
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