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June 14, 2015 13:19
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qi error handling sample
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| #include <boost/config/warning_disable.hpp> | |
| #include <boost/spirit/include/qi.hpp> | |
| #include <boost/spirit/include/phoenix.hpp> | |
| #include <boost/fusion/include/adapt_struct.hpp> | |
| #include <boost/variant/recursive_variant.hpp> | |
| #include <boost/spirit/home/support/iterators/line_pos_iterator.hpp> | |
| #include <iostream> | |
| #include <fstream> | |
| #include <string> | |
| #include <vector> | |
| #include <boost/format.hpp> | |
| namespace client { | |
| namespace fusion = boost::fusion; | |
| namespace phx = boost::phoenix; | |
| namespace qi = boost::spirit::qi; | |
| namespace ascii = boost::spirit::ascii; | |
| struct mini_xml; | |
| typedef boost::variant< | |
| boost::recursive_wrapper<mini_xml> | |
| , std::string | |
| > | |
| mini_xml_node; | |
| struct mini_xml { | |
| std::string name; | |
| std::vector<mini_xml_node> children; | |
| }; | |
| } // namespace client | |
| BOOST_FUSION_ADAPT_STRUCT( | |
| client::mini_xml, | |
| (std::string, name), | |
| (std::vector<client::mini_xml_node>, children) | |
| ) | |
| namespace client { | |
| int constexpr tabsize = 4; | |
| void tab(int indent) | |
| { | |
| for (int i = 0; i < indent; ++i) | |
| std::cout << ' '; | |
| } | |
| struct mini_xml_printer | |
| { | |
| mini_xml_printer(int indent = 0) : indent(indent) {} | |
| void operator()(mini_xml const& xml) const; | |
| int indent; | |
| }; | |
| struct mini_xml_node_printer : boost::static_visitor<> | |
| { | |
| mini_xml_node_printer(int indent = 0) : indent(indent) {} | |
| void operator()(mini_xml const& xml) const | |
| { | |
| mini_xml_printer(indent+tabsize)(xml); | |
| } | |
| void operator()(std::string const& text) const | |
| { | |
| tab(indent + tabsize); | |
| std::cout << "text: \"" << text << '"' << std::endl; | |
| } | |
| int indent; | |
| }; | |
| void mini_xml_printer::operator()(mini_xml const& xml) const | |
| { | |
| tab(indent); | |
| std::cout << "tag: " << xml.name << std::endl; | |
| tab(indent); | |
| std::cout << '{' << std::endl; | |
| for (mini_xml_node const& node : xml.children) { | |
| boost::apply_visitor(mini_xml_node_printer(indent), node); | |
| } | |
| tab(indent); | |
| std::cout << '}' << std::endl; | |
| } | |
| template<typename Iterator> | |
| struct mini_xml_grammar | |
| : qi::grammar<Iterator, mini_xml(), qi::locals<std::string>, ascii::space_type> | |
| { | |
| mini_xml_grammar() | |
| : mini_xml_grammar::base_type(xml, "xml") | |
| { | |
| using qi::lit; | |
| using qi::lexeme; | |
| using qi::on_error; | |
| using qi::fail; | |
| using ascii::char_; | |
| using ascii::string; | |
| using namespace qi::labels; | |
| using phx::construct; | |
| using phx::val; | |
| text %= lexeme[+(char_ - '<')]; | |
| node %= xml | text; | |
| start_tag %= | |
| '<' | |
| >> !lit('/') | |
| > lexeme[+(char_ - '>')] | |
| > '>' | |
| ; | |
| end_tag = | |
| "</" | |
| > string(_r1) | |
| > '>' | |
| ; | |
| xml %= | |
| start_tag[_a = _1] | |
| > *node | |
| > end_tag(_a) | |
| ; | |
| xml.name("xml"); | |
| node.name("node"); | |
| text.name("text"); | |
| start_tag.name("start_tag"); | |
| end_tag.name("end_tag"); | |
| on_error<fail> ( | |
| xml | |
| , std::cerr << phx::val("Error in ") | |
| << phx::bind([](auto const begin, auto const err_pos) { | |
| return (boost::format("line:%1%, col:%2%") % boost::spirit::get_line(err_pos) % boost::spirit::get_column(begin, err_pos)).str(); | |
| }, _1, _3) << '\n' | |
| << "Expected " << _4 << "\n\n" | |
| << phx::bind([this](auto const begin, auto const end, auto const err_itr) { | |
| return std::string { | |
| boost::spirit::get_line_start(begin, err_itr), | |
| std::find_if(err_itr, end, [](auto c) { return c == '\r' || c == '\n'; }) | |
| } + '\n' + std::string(boost::spirit::get_column(begin, err_itr)-1, ' ') + "^ here"; | |
| }, _1, _2, _3) | |
| << std::endl); | |
| } | |
| qi::rule<Iterator, mini_xml(), qi::locals<std::string>, ascii::space_type> xml; | |
| qi::rule<Iterator, mini_xml_node(), ascii::space_type> node; | |
| qi::rule<Iterator, std::string(), ascii::space_type> text; | |
| qi::rule<Iterator, std::string(), ascii::space_type> start_tag; | |
| qi::rule<Iterator, void(std::string), ascii::space_type> end_tag; | |
| }; | |
| } // namespace client | |
| int main(int argc, char const* argv[]) | |
| { | |
| char const* filename; | |
| if (argc > 1) filename = argv[1]; | |
| else { | |
| std::cerr << "Error: No input file provided." << std::endl; | |
| return 1; | |
| } | |
| std::ifstream in(filename, std::ios_base::in); | |
| if (!in) | |
| { | |
| std::cerr << "Error: Could not open input file: " << filename << std::endl; | |
| return 1; | |
| } | |
| std::string storage; | |
| in.unsetf(std::ios::skipws); | |
| std::copy( | |
| std::istream_iterator<char>(in), | |
| std::istream_iterator<char>(), | |
| std::back_inserter(storage)); | |
| typedef client::mini_xml_grammar<boost::spirit::line_pos_iterator<std::string::const_iterator>> mini_xml_grammar; | |
| mini_xml_grammar xml; | |
| client::mini_xml ast; | |
| using boost::spirit::ascii::space; | |
| auto iter = boost::spirit::line_pos_iterator<std::string::const_iterator>(storage.cbegin()); | |
| auto end = boost::spirit::line_pos_iterator<std::string::const_iterator>(storage.end()); | |
| bool r = boost::spirit::qi::phrase_parse(iter, end, xml, space, ast); | |
| if (r && iter == end) | |
| { | |
| std::cout << "Succeeded!" << std::endl; | |
| client::mini_xml_printer printer; | |
| printer(ast); | |
| } | |
| else | |
| { | |
| std::cout << "failed" << std::endl; | |
| } | |
| return 0; | |
| } |
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