boost :: regex_search和替換valgrind錯誤

Question

當我試圖用boost :: regex搜索和替換字符串中的一些數據時，我有很多錯誤valgrind。 我得到正確的輸出，但我有點害怕這個錯誤

有趣的事情是，當我用替換註釋行，我沒有得到任何錯誤來自行搜索。

所以，我有以下功能

static void replaceVar(std::string & input, std::map<std::string, TEMPLATE_PARAM> &param) 
    { 
    boost::regex ex(REGEX_TAG); 
    boost::match_results<std::string::const_iterator> extend; 
    std::string::const_iterator start, end; 
    boost::match_flag_type flags; 

    start = input.begin(); 
    end = input.end(); 
    flags = boost::match_default; 
    while (boost::regex_search(start, end, extend, ex, flags)) // line 78 
     { 
     try 
      { 
      const std::string *ptr = tools::visitor_fct<std::string>(param.at(extend[1])); // this line is working fine 
      if (ptr != nullptr) 
       input = boost::regex_replace(input, ex, *ptr, boost::match_default | boost::format_first_only); //line 84 
      } 
     catch (const std::out_of_range& err) 
      { 
      input = boost::regex_replace(input, ex, std::string(""), boost::match_default | boost::format_first_only); 
      } 
     start = extend[0].second; 
     end = input.end(); 
     flags |= boost::match_prev_avail; 
     flags |= boost::match_not_bob; 
     } 
    } 

我碰到的valgrind以下輸出

==21743== Thread 2: 
==21743== Invalid read of size 1 
==21743== at 0x54C24B0: boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::find_restart_any() (in /usr/local/lib/libboost_regex.so.1.53.0) 
==21743== by 0x54D83BA: boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::find_imp() (in /usr/local/lib/libboost_regex.so.1.53.0) 
==21743== by 0x4BADB7: bool boost::regex_search<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(__gnu_cxx::__normal_iterator<char const*, std::string>, __gnu_cxx::__normal_iterator<char const*, std::string>, boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, __gnu_cxx::__normal_iterator<char const*, std::string>) (regex_search.hpp:56) 
==21743== by 0x4F40D7: bool boost::regex_search<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(__gnu_cxx::__normal_iterator<char const*, std::string>, __gnu_cxx::__normal_iterator<char const*, std::string>, boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags) (regex_search.hpp:42) 
==21743== by 0x4F2BB4: ... line 78 

和

==21743== Address 0x6543315 is 197 bytes inside a block of size 293 free'd 
==21743== at 0x4C2A4BC: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==21743== by 0x57EBC12: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string() (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.16) 
==21743== by 0x4F2B0C: (l:84) 

我認爲這是在創造的所有作業這個錯誤，因爲當我只把

boost::regex_replace(input, ex, *ptr, boost::match_default | boost::format_first_only); //line 84 

我沒有得到任何的valgrind錯誤

我也試圖從regex_replace的輸出創建一個新的字符串，然後將其分配到輸出中，但我仍然得到這個錯誤

有任何想法嗎 ？

Answer 1

要刪除所有這些錯誤valgrinds我只需要重新啓動循環每次在每次更改，因爲結束和字符串的開始是不一樣的。

所以我只是改變了環路

bool flag = true; 
while (flag) 
    { 
    flag = false; 
    start = input.begin(); 
    end = input.end(); 
    while (boost::regex_search(start, end, extend, ex, boost::match_default)) 
     { 
     try 
      { 
      const std::string *ptr = tools::visitor_fct<std::string>(param.at(extend[1])); 
      if (ptr != nullptr) 
       input = boost::regex_replace(input, ex, *ptr, boost::match_default | boost::format_first_only); 
      } 
     catch (const std::out_of_range& err) 
      { 
      input = boost::regex_replace(input, ex, std::string(""), boost::match_default | boost::format_first_only); 
      } 
     flag = true; 
     break; 
     } 
    } 

，一切工作正常。