c – Boost.Spirit.Qi用法中的错误雪崩

这有什么问题？

#include <iostream>
#include <boost/lambda/lambda.hpp>
#include <boost/spirit/include/qi.hpp>

void parsePathTest(const std::string &path)
{
    namespace lambda = boost::lambda;
    using namespace boost::spirit;

    const std::string permitted = "._-#@a-zA-Z0-9";
    const std::string physicalPermitted = permitted + "/\";
    const std::string archivedPermitted = permitted + ":{}";

    std::string physical,archived;

    // avoids non-const reference to rvalue
    std::string::const_iterator begin = path.begin(),end = path.end();

    // splits a string like "some/nice-path/while_checking:permitted#symbols.bin"
    // as physical = "some/nice-path/while_checking"
    // and archived = "permitted#symbols.bin" (if this portion exists)
    // I could barely find out the type for this expression
    auto expr
        =   ( +char_(physicalPermitted) ) [lambda::var(physical) = lambda::_1]
            >> -(
                    ':'
                    >> (
                           +char_(archivedPermitted) [lambda::var(archived) = lambda::_1]
                       )
                )
        ;

    // the error occurs in a template instantiated from here
    qi::parse(begin,end,expr);

    std::cout << physical << 'n' << archived << 'n';
}

错误的数量是巨大的;我会建议那些想要帮助他们进行编译的人(相信我,在这里粘贴是不切实际的).我使用的是最新的TDM-GCC版本(GCC 4.4.1)和Boost版本1.39.00.

作为奖励,我想问另外两件事：C 0x的新static_assert功能是否会在这个意义上帮助Boost,以及我上面引用的实现是否是一个好主意,或者我是否应该使用Boost的字符串算法库.后者可能会提供更好的表现吗？

谢谢.

– 编辑

以下非常小的示例首先失败,其错误与上面的代码完全相同.

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

int main()
{
    using namespace boost::spirit;

    std::string str = "sample";
    std::string::const_iterator begin(str.begin()),end(str.end());

    auto expr
        =   ( +char_("a-zA-Z") )
        ;

    // the error occurs in a template instantiated from here
    if (qi::parse(begin,expr))
    {
        std::cout << "[+] Parsed!n";
    }
    else
    {
        std::cout << "[-] Parsing failed.n";
    }

    return 0;
}

– 编辑2

我仍然不知道为什么它在我的旧版Boost(1.39)中不起作用,但升级到Boost 1.42解决了这个问题.以下代码与Boost 1.42编译并完美运行：

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

int main()
{
    using namespace boost::spirit;

    std::string str = "sample";
    std::string::const_iterator begin(str.begin()),end(str.end());

    auto expr
        =   ( +qi::char_("a-zA-Z") ) // notice this line; char_ is not part of 
                                     // boost::spirit anymore (or maybe I didn't 
                                     // include the right headers,but,regardless,// khaiser said I should use qi::char_,so here 
                                     // it goes)
        ;

    // the error occurs in a template instantiated from here
    if (qi::parse(begin,expr))
    {
        std::cout << "[+] Parsed!n";
    }
    else
    {
        std::cout << "[-] Parsing failed.n";
    }

    return 0;
}

感谢您的提示,hkaiser.