问促进：：精神:气：：规则或结构包含气：：规则的解析结果
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Stack Overflow用户

提问于 2014-12-03 07:03:29

回答 2查看 440关注 0票数 1

我要做的是在运行时从ABNF语法文件创建一个解析器。我已经在qi：：语法中实现了所有ABNF规则，如下所示：

typedef /*qi::rule or struct containing qi::rule*/ parserRule

    [...] //all other ABNF rules according to RFC 5234

    rule =
            (
                    rulename[qi::_a = qi::_1] >>
                    definedAs >>
                    elements[qi::_b = qi::_1] >>
                    cNl
            )[qi::_val = px::bind(&AbnfParserFactory::fromRule, &factory, qi::_a, qi::_b)];


    rulelist =
            +(
                    rule[px::push_back(qi::_a, qi::_1)] |
                    (*cWsp >> cNl)
             ) >>
             eps[qi::_val = px::bind(&AbnfParserFactory::fromRulelist, &factory, qi::_a)];


qi::rule<Iterator, std::map<std::string, parserRule>(), qi::locals<std::vector<parserRule> > >  rulelist;
qi::rule<Iterator, parserRule(), qi::locals<std::string>, qi::locals<parserRule> >              rule;
[...] // all other ABNF rules

在ParserFactory内部，根据语法中的读内容创建了一个新的qi：：规则：

std::map<std::string, ReturnType> fromRulelist(std::vector<ReturnType> &rules)
{
    // return a map with <rulename, rule>
};

parserRule fromRule(std::string &name, parserRule &rule)
{
    //name the rule an return it
    rule.name(name);
    return rule;
};

问题在于parserRule的类型。

如果我使用qi::rule作为类型(就像我通常想要的那样)，我将丢失在ParserFactory中分配的每个规则名称(如在fromRule中)。我想这是精神内部工作方式造成的(=操作符总是创建一个新的、未命名的规则。=用于分配px::bind函数结果)

但是，如果我试图将qi::rule封装到一个结构中以避免这个问题，那么我就无法再编译我的代码并进行精神调试。以下是我尝试过的：

typedef qi::rule<std::string::const_iterator, std::string()> FactoryRuleType;
struct parserRule
{
    FactoryRuleType mRule;
};

BOOST_FUSION_ADAPT_STRUCT(
 parserRule,
(FactoryRuleType, mRule)
)

[...] //rule definitions like above

debug(rule);
debug(rulelist);
[...] //debug all other rules

这将给我带来大量编译错误(这是很长的一段时间才能在这里发布)。为了解决这个问题，我已经找了好几天了，但没有任何运气。我希望我能提到足够的细节。

任何帮助都是非常感谢的。

编译输出节选：

/usr/include/boost/proto/operators.hpp:295:9: note:   template argument deduction/substitution failed:
/usr/include/boost/proto/operators.hpp: In substitution of ‘template<class Left, class Right> const typename boost::proto::detail::enable_binary<boost::proto::domainns_::deduce_domain, boost::proto::detail::not_a_grammar, boost::mpl::or_<boost::proto::is_extension<Arg>, boost::proto::is_extension<Right> >, boost::proto::tagns_::tag::shift_left, Left&, Right&>::type boost::proto::exprns_::operator<<(Left&, Right&) [with Left = std::basic_ostream<char>; Right = const boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >]’:
/usr/include/boost/spirit/home/support/attributes.hpp:1226:17:   required from ‘static void boost::spirit::traits::print_attribute_debug<Out, T, Enable>::call_impl3(Out&, const T_&, mpl_::false_) [with T_ = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >; Out = std::basic_ostream<char>; T = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >; Enable = void; mpl_::false_ = mpl_::bool_<false>]’
/usr/include/boost/spirit/home/support/attributes.hpp:1242:67:   required from ‘static void boost::spirit::traits::print_attribute_debug<Out, T, Enable>::call_impl2(Out&, const T_&, mpl_::false_) [with T_ = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >; Out = std::basic_ostream<char>; T = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >; Enable = void; mpl_::false_ = mpl_::bool_<false>]’
/usr/include/boost/spirit/home/support/attributes.hpp:1277:52:   required from ‘static void boost::spirit::traits::print_attribute_debug<Out, T, Enable>::call_impl(Out&, const T_&, mpl_::true_) [with T_ = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >; Out = std::basic_ostream<char>; T = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >; Enable = void; mpl_::true_ = mpl_::bool_<true>]’
/usr/include/boost/spirit/home/support/attributes.hpp:1283:52:   required from ‘static void boost::spirit::traits::print_attribute_debug<Out, T, Enable>::call(Out&, const T&) [with Out = std::basic_ostream<char>; T = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >; Enable = void]’
/usr/include/boost/spirit/home/support/attributes.hpp:1303:53:   required from ‘void boost::spirit::traits::print_attribute(Out&, const T&) [with Out = std::basic_ostream<char>; T = boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >]’
/usr/include/boost/spirit/home/support/attributes.hpp:1196:57:   [ skipping 34 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
/usr/include/boost/function/function_template.hpp:722:7:   required from ‘boost::function4<R, T1, T2, T3, T4>::function4(Functor, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type) [with Functor = boost::spirit::qi::debug_handler<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, boost::spirit::context<boost::fusion::cons<FactoryReturnType&, boost::fusion::nil>, boost::fusion::vector0<> >, boost::spirit::unused_type, boost::spirit::qi::simple_trace>; R = bool; T0 = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&; T1 = const __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&; T2 = boost::spirit::context<boost::fusion::cons<FactoryReturnType&, boost::fusion::nil>, boost::fusion::vector0<> >&; T3 = const boost::spirit::unused_type&; typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type = int]’
/usr/include/boost/function/function_template.hpp:1069:16:   required from ‘boost::function<R(T0, T1, T2, T3)>::function(Functor, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type) [with Functor = boost::spirit::qi::debug_handler<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, boost::spirit::context<boost::fusion::cons<FactoryReturnType&, boost::fusion::nil>, boost::fusion::vector0<> >, boost::spirit::unused_type, boost::spirit::qi::simple_trace>; R = bool; T0 = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&; T1 = const __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&; T2 = boost::spirit::context<boost::fusion::cons<FactoryReturnType&, boost::fusion::nil>, boost::fusion::vector0<> >&; T3 = const boost::spirit::unused_type&; typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type = int]’
/usr/include/boost/function/function_template.hpp:1124:5:   required from ‘typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, boost::function<R(T0, T1, T2, T3)>&>::type boost::function<R(T0, T1, T2, T3)>::operator=(Functor) [with Functor = boost::spirit::qi::debug_handler<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, boost::spirit::context<boost::fusion::cons<FactoryReturnType&, boost::fusion::nil>, boost::fusion::vector0<> >, boost::spirit::unused_type, boost::spirit::qi::simple_trace>; R = bool; T0 = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&; T1 = const __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&; T2 = boost::spirit::context<boost::fusion::cons<FactoryReturnType&, boost::fusion::nil>, boost::fusion::vector0<> >&; T3 = const boost::spirit::unused_type&; typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, boost::function<R(T0, T1, T2, T3)>&>::type = boost::function<bool(__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&, const __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&, boost::spirit::context<boost::fusion::cons<FactoryReturnType&, boost::fusion::nil>, boost::fusion::vector0<> >&, const boost::spirit::unused_type&)>&]’
/usr/include/boost/spirit/home/qi/nonterminal/debug_handler.hpp:122:13:   required from ‘void boost::spirit::qi::debug(boost::spirit::qi::rule<Iterator, T1, T2, T3, T4>&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >; T1 = FactoryReturnType(); T2 = boost::spirit::unused_type; T3 = boost::spirit::unused_type; T4 = boost::spirit::unused_type]’
../src/AbnfReader.hpp:350:14:   required from ‘AbnfRules<Iterator>::AbnfRules() [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >]’
../src/AbnfReader.cpp:27:12:   required from here
/usr/include/boost/proto/operators.hpp:295:9: error: no type named ‘type’ in ‘struct boost::proto::detail::enable_binary<boost::proto::domainns_::deduce_domain, boost::proto::detail::not_a_grammar, boost::mpl::or_<boost::proto::is_extension<std::basic_ostream<char> >, boost::proto::is_extension<const boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> > >, mpl_::bool_<false>, mpl_::bool_<false>, mpl_::bool_<false> >, boost::proto::tagns_::tag::shift_left, std::basic_ostream<char>&, const boost::spirit::qi::reference<const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>()> >&>’
make: *** [src/AbnfReader.o] Error 1

c++

parsing

boost-spirit

回答 2

Stack Overflow用户

回答已采纳

发布于 2014-12-06 12:38:25

这太尴尬了。当我试图像sehe建议的那样编写一个SSCCE时，我发现我的方法实际上一直在起作用。为了解决这个问题我遇到了很多麻烦.:C

下面是我想要做的事情的一个例子。虽然有效，但行为仍然有点奇怪，这也是我认为它不是这样工作的原因。

#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>

namespace qi = boost::spirit::qi;
namespace px = boost::phoenix;
namespace ascii = boost::spirit::ascii;

typedef qi::rule<std::string::const_iterator, std::string()> parserRule;


namespace std
{
std::ostream& operator<<(std::ostream& stream, const parserRule& val);
}
std::ostream& std::operator<<(std::ostream& stream, const parserRule& val)
{
    stream << "RULE( " << val.name();
    stream << " )";
    return stream;
}

class Factory
{
public:
    Factory(){}
    parserRule createParser(std::string str)
    {
        parserRule r;
        r = qi::char_(str);
        r.name("FactoryRule");
        std::cout << r.name() << " now parses >" + str + "<" << std::end;
        return r;
    }
};

template <typename Iterator>
struct TestGrammar : qi::grammar<Iterator, parserRule()>
{

    TestGrammar() : TestGrammar::base_type(start, "Test grammar")
    {
        start = stringRule.alias();
        stringRule =    (
                ascii::char_("'") >>
                *(ascii::char_ - ascii::char_("'"))[qi::_a += qi::_1] >>
                ascii::char_("'")
        )[qi::_val = px::bind(&Factory::createParser, &factory, qi::_a)];

        start.name("Start");
        stringRule.name("StringRule");

        qi::debug(start);       // shows "RULE( unnamed-rule )"
        qi::debug(stringRule);  // shows "RULE( unnamed-rule )"
    }

    qi::rule<Iterator, parserRule() > start;
    qi::rule<Iterator, parserRule(), qi::locals<std::string> > stringRule;
    Factory factory;
};

int main()
{
    typedef std::string::const_iterator iterator_type;
    typedef TestGrammar<iterator_type> TGrammar;


    TGrammar test_parser;

    std::string test = "parse THIS!";
    std::string input = "'"+test+"'";
    parserRule result;

    std::string::const_iterator iter = input.begin();
    std::string::const_iterator end = input.end();

    bool r = parse(iter, end, test_parser, result);

    if (r && iter == end)
    {
        std::cout << "-------------------------\n";
        std::cout << "1st Parsing succeeded\n";
        std::cout << "-------------------------\n";
    }
    else
    {
        std::string rest(iter, end);
        std::cout << "-------------------------\n";
        std::cout << "1st Parsing failed\n";
        std::cout << "stopped at: \"" << rest << "\"\n";
        std::cout << "-------------------------\n";
    }

    iterator_type first(test.begin()), last(test.end());

    qi::debug(result); //shows correct rule name
    r = qi::phrase_parse(first, last, result, boost::spirit::ascii::space);

    if (r && iter == end)
    {
        std::cout << "-------------------------\n";
        std::cout << "2nd Parsing succeeded\n";
        std::cout << "-------------------------\n";
    }
    else
    {
        std::string rest(first, last);
        std::cout << "-------------------------\n";
        std::cout << "2nd Parsing failed\n";
        std::cout << "stopped at: \"" << rest << "\"\n";
        std::cout << "-------------------------\n";
    }
}

这是输出：

FactoryRule now parses >parse THIS!<
<Start>
  <try>'parse THIS!'</try>
  <StringRule>
    <try>'parse THIS!'</try>
    <success></success>
    <attributes>[[RULE( unnamed-rule )]]</attributes><locals>(parse THIS!)</locals>
  </StringRule>
  <success></success>
  <attributes>[[RULE( unnamed-rule )]]</attributes>
</Start>
-------------------------
1st Parsing succeeded
-------------------------
<FactoryRule>
  <try>parse THIS!</try>
  <success>arse THIS!</success>
  <attributes>[[p]]</attributes>
</FactoryRule>
-------------------------
2nd Parsing succeeded
-------------------------

如您所见，调试规则start和stringRule将始终将“规则(未命名-规则)”显示为属性。这使我相信，由于在分配=-operator结果时使用了px::bind，所以分配的规则名丢失了。因为调试result规则会显示正确的名称，所以我假设“未命名规则”输出并不显示正确的最终合成属性，而是显示当前的“空”属性。

当我看到“未命名的规则”和花费了很多天的时间试图解决这个问题，甚至在没有通过调试result规则来测试整个事情的情况下在这里问的时候，我感到非常遗憾。

不管怎样，谢谢你帮我。我希望这至少对其他人有用。

票数 1

Stack Overflow用户

发布于 2014-12-03 07:31:06

这里有两个问题，仅凭经验，无需编写进一步的代码：

单元素适配结构会产生问题，请参阅:链接来了。
调试信息需要调试打印特征的专门化(返回到ostream流)。显然，对于qi::rule来说，这一点还没有完成。所以要么加进去。也许，只是也许您可以使包含的结构iostream-能够避免它(但我担心融合适应可能优先。值得一试)

问:是的，你是对的。我必须在运行时动态地编写语法。为了确保这是可能的，我已经编写了一堆测试片段，它们按预期工作。

直截了当地说:精神不是实现这一目标的工具。灵性是一个工具，它从"praser表达式“(即表达式模板)生成静态编译的语法。总体目标是编译时，使用静态多态性进行完全优化。我建议可能创建一组运行时多态解析器组件(反过来，您可以使用精灵:实现这些组件)，并从它们中构建动态语法。一种可能的中间路线是使用qi::lazy和一组预定义的不可变的“原子”规则(所以不是动态合成的)，并使用这些引用的“原子”规则组成解析器。
基本上，只要您不尝试动态组合表达式模板(而是准备好的类型擦除的非终端)，您就应该没事。 如果你需要更多的话，你很快就会到UB的。有些时候，您可以使用boost::proto::deep_copy来解决问题，但这是有局限性的。