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