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  1. #include <iostream>
  2. #include <cstdlib>
  3. #include <string>
  4. #include <regex>
  5. using namespace std;
  6.  
  7. template<class BidirIt, class Traits, class CharT, class UnaryFunction>
  8. std::basic_string<CharT> regex_replace(BidirIt first, BidirIt last,
  9.     const std::basic_regex<CharT,Traits>& re, UnaryFunction f)
  10. {
  11.     std::basic_string<CharT> s;
  12.  
  13.     typename std::match_results<BidirIt>::difference_type
  14.         positionOfLastMatch = 0;
  15.     auto endOfLastMatch = first;
  16.  
  17.     auto callback = [&](const std::match_results<BidirIt>& match)
  18.     {
  19.         auto positionOfThisMatch = match.position(0);
  20.         auto diff = positionOfThisMatch - positionOfLastMatch;
  21.  
  22.         auto startOfThisMatch = endOfLastMatch;
  23.         std::advance(startOfThisMatch, diff);
  24.  
  25.         s.append(endOfLastMatch, startOfThisMatch);
  26.         s.append(f(match));
  27.  
  28.         auto lengthOfMatch = match.length(0);
  29.  
  30.         positionOfLastMatch = positionOfThisMatch + lengthOfMatch;
  31.  
  32.         endOfLastMatch = startOfThisMatch;
  33.         std::advance(endOfLastMatch, lengthOfMatch);
  34.     };
  35.  
  36.     std::sregex_iterator begin(first, last, re), end;
  37.     std::for_each(begin, end, callback);
  38.  
  39.     s.append(endOfLastMatch, last);
  40.  
  41.     return s;
  42. }
  43.  
  44. template<class Traits, class CharT, class UnaryFunction>
  45. std::string regex_replace(const std::string& s,
  46.     const std::basic_regex<CharT,Traits>& re, UnaryFunction f)
  47. {
  48.     return regex_replace(s.cbegin(), s.cend(), re, f);
  49. }
  50.  
  51. std::string my_callback(const std::smatch& m) {
  52.   if (m.str(1).length() % 2 == 0) {
  53.   	return "&quot;";
  54.   } else {
  55.   	return m.str(0);
  56.   }
  57. }
  58.  
  59. int main() {
  60. 	std::string str = "\"Hello people \" how are you doing \" what are \" you upto \"";
  61. 	cout << regex_replace(str, regex("(^\\s*\"|\"\\s*$)|\""), my_callback) << endl;
  62.  
  63.     return 0;
  64. }
Success #stdin #stdout 0s 16168KB
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"Hello people &quot; how are you doing &quot; what are &quot; you upto "
https://ideone.com/xp3rf8
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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