使用 boost::wave 时的运行时错误消息

Question

我收到以下运行时错误消息

terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::wave::cpplexer::lexing_exception> >'
  what():  boost::wave::lexing_exception

当我尝试运行以下代码时：

#include <vector>
#include <algorithm>
#include <boost/wave.hpp>
#include <boost/wave/cpplexer/cpp_lex_token.hpp>
#include <boost/wave/cpplexer/cpp_lex_iterator.hpp>

std::string strip_comments(std::string const& input)
{
    std::string output;
    typedef boost::wave::cpplexer::lex_token<> token_type;
    typedef boost::wave::cpplexer::lex_iterator<token_type> lexer_type;
    typedef token_type::position_type position_type;

    position_type pos;

    lexer_type it = lexer_type(input.begin(), input.end(), pos, 
        boost::wave::language_support(
            boost::wave::support_cpp|boost::wave::support_option_long_long));
    lexer_type end = lexer_type();

    for (;it != end; ++it)
    {
        if (*it != boost::wave::T_CCOMMENT
         && *it != boost::wave::T_CPPCOMMENT)
        {
            output += std::string(it->get_value().begin(), it->get_value().end());
        }
    }
    return output;
}

int main()
{
    std::string text="aaa bbb /*cccc*/ ddd // eee";
    std::cout<<strip_comments(text)<<std::endl;
    return 0;
}

我使用 gcc 编译器：

g++ -std=c++11 test.cpp -o test -lboost_wave -lboost_system

此代码应该从// 和/* ... */ 指定的文本中删除C++ cmets。

这里是 gdb 回溯：

GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...done.
[New LWP 10573]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `./a.out'.
Program terminated with signal SIGABRT, Aborted.
#0  0x00007ff38fe96cc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
56  ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  0x00007ff38fe96cc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007ff38fe9a0d8 in __GI_abort () at abort.c:89
#2  0x00007ff3904cb78d in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#3  0x00007ff3904c97f6 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#4  0x00007ff3904c9841 in std::terminate() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#5  0x00007ff3904c9a58 in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6  0x00007ff390a9e063 in void boost::throw_exception<boost::wave::cpplexer::lexing_exception>(boost::wave::cpplexer::lexing_exception const&)
    () from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#7  0x00007ff390aa3a5e in boost::wave::cpplexer::re2clex::lexer<__gnu_cxx::__normal_iterator<char const*, std::string>, boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > >, boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::report_error(boost::wave::cpplexer::re2clex::Scanner const*, int, char const*, ...) ()
   from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#8  0x00007ff390aaf2f0 in boost::wave::cpplexer::re2clex::scan(boost::wave::cpplexer::re2clex::Scanner*) ()
   from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#9  0x00007ff390aa4329 in boost::wave::cpplexer::re2clex::lexer<__gnu_cxx::__normal_iterator<char const*, std::string>, boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > >, boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::get(boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > >&) () from /usr/lib/x86_64-linux-gnu/libboost_wave.so.1.54.0
#10 0x000000000040a3b8 in boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::get_next<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=..., result=...)
    at /usr/include/boost/wave/cpplexer/cpp_lex_iterator.hpp:80
#11 0x0000000000409efb in boost::spirit::iterator_policies::split_functor_input::unique<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, true>::advance_input<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util---Type <return> to continue, or q <return> to quit---
::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=...)
    at /usr/include/boost/spirit/home/support/iterators/detail/split_functor_input_policy.hpp:91
#12 0x000000000040969f in boost::spirit::iterator_policies::multi_pass_unique<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::ref_counted::unique, boost::spirit::iterator_policies::no_check::unique, boost::spirit::iterator_policies::split_functor_input::unique<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, true>, boost::spirit::iterator_policies::split_std_deque::unique<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, true, true, true>::advance_input<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=...)
    at /usr/include/boost/spirit/home/support/iterators/detail/combine_policies.hpp:441
#13 0x0000000000408d7c in boost::spirit::iterator_policies::split_std_deque::unique<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::increment<boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> > > (mp=...)
    at /usr/include/boost/spirit/home/support/iterators/detail/split_std_deque_policy.hpp:107
#14 0x0000000000408450 in boost::spirit::multi_pass<std::pair<boost::wave::cpplexer::impl::lex_iterator_functor_shim<boost::wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >, boost::wave::cpplexer::lex_input_interface<boost:---Type <return> to continue, or q <return> to quit---
:wave::cpplexer::lex_token<boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >*>, boost::spirit::iterator_policies::default_policy<boost::spirit::iterator_policies::ref_counted, boost::spirit::iterator_policies::no_check, boost::spirit::iterator_policies::split_functor_input, boost::spirit::iterator_policies::split_std_deque> >::operator++ (this=0x7fff7d8f66e0)
    at /usr/include/boost/spirit/home/support/iterators/multi_pass.hpp:119
#15 0x000000000040680e in strip_comments (input="aaa bbb /*cccc*/ ddd // eee") at test.cpp:23
#16 0x0000000000406927 in main () at test.cpp:37

更新

感谢 jpo38 的评论。我通过

初始化了pos

position_type pos(0);

并且修复了之前的运行时错误。 现在，我得到了一个不同的运行时错误：

#0  0x0000000000406ff8 in std::char_traits<char>::length (__s=0x0) at /usr/include/c++/4.9/bits/char_traits.h:263
#1  0x0000000000408504 in boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> >::flex_string (this=0x7ffee3d536a0, s=0x0, a=...)
    at /usr/include/boost/wave/util/flex_string.hpp:1502
#2  0x000000000040693f in strip_comments (input="aaa bbb /*cccc*/ ddd // eee") at test.cpp:16
#3  0x0000000000406bf0 in main () at test.cpp:37

我发现了一般异常并尝试通过以下方式显示它：

std::cout << "Error occurred: " << ex.what() << std::endl;

虽然没有成功。

Answer 1

boost 喜欢异常编程。意思是异常用于引发错误和警告....我讨厌这样，但如果您使用那些出色的 c++ 库，则需要接受它。如果您不小心并抓住它们，异常会导致“崩溃”，就像这样：

std::string strip_comments(std::string const& input)
{
    std::string output;
    typedef boost::wave::cpplexer::lex_token<> token_type;
    typedef boost::wave::cpplexer::lex_iterator<token_type> lexer_type;
    typedef token_type::position_type position_type;

    boost::wave::util::file_position_type current_position; // for error reporting

    try
    {
        position_type pos;

        lexer_type it = lexer_type(input.begin(), input.end(), pos, 
            boost::wave::language_support(
            boost::wave::support_cpp|boost::wave::support_option_long_long));
    lexer_type end = lexer_type();

        for (;it != end; ++it)
        {
            current_position = (*it).get_position();  // for error reporting

            if (*it != boost::wave::T_CCOMMENT
             && *it != boost::wave::T_CPPCOMMENT)
            {
                output += std::string(it->get_value().begin(), it->get_value().end());
            }
        }            
    }
    catch (boost::wave::cpplexer::lexing_exception const& e) {
        // some lexing error
        std::cerr
            << e.file_name() << "(" << e.line_no() << "): "
            << e.description() << std::endl;
    }
    catch (std::exception const& e) {
        // use last recognized token to retrieve the error position
        std::cerr
            << current_position.get_file()
            << "(" << current_position.get_line() << "): "
            << "exception caught: " << e.what()
            << std::endl;
    }
    catch (...) {
        // use last recognized token to retrieve the error position
        std::cerr
            << current_position.get_file()
            << "(" << current_position.get_line() << "): "
            << "unexpected exception caught." << std::endl;
    }  
    return output;
}

然后，您将收到这条漂亮且安全的消息，而不是“崩溃”：

(1)：警告：通用词法分析器警告：未终止的“C++”样式注释

您可以看到，通过不捕获异常，一个简单的提升警告在您的级别转换为严重崩溃；-)

我不熟悉 wave 库，但在字符串末尾添加 \n 可以解决问题，然后不再报告错误（顺便说一句，这实际上只是一个警告）：

将主函数文本字符串更改为：std::string text="aaa bbb /*cccc*/ ddd // eee\n";，程序将输出aaa bbb ddd。

您可以添加此\n，但您也可以重新编写代码以在循环内尝试/捕获，然后报告但忽略警告。

注意：boost::wave 预期 EOL 的事实可能与这个众所周知的 C++ 警告有关（但它实际上只是一个警告）："No newline at end of file" compiler warning