C++正則表達式：有條件替換

Question

我想用正則表達式替換文本中所有不在字典中唯一標識符的單詞。我如何做到這一點？也許使用回調函數？

std::string getToken(const std::smatch &m) { 
    static int x = 0; 
    std::string keyword = m[0].str(); 
    std::set<std::string> keywords = {"foo", "bar"}; 

    if (keywords.find(keyword) != keywords.end()) { 
     return keyword; 
    } else { 
     return "i" + x++; 
    } 
} 

std::string replacer(std::string text) { 
    std::string ret = text; 

    ret = std::regex_replace(ret , std::regex("\\b.*\\b"), getToken); // It's don't works 

    return ret; 
} 

Answer 1

使用regex_token_iterator

#include <regex> 
#include <string> 
#include <sstream> 
#include <set> 
#include <map> 

std::string replacer(std::string text) { 
    std::string output_text; 
    std::set<std::string> keywords = { "foo", "bar" }; 
    std::map<std::string, int> ids = {}; 

    int counter = 0; 
    auto callback = [&](std::string const& m){ 
     std::istringstream iss(m); 
     std::string n; 
     if (iss >> n) 
     { 
      if (keywords.find(m) != keywords.end()) { 
       output_text += m + " "; 
      } 
      else { 
       if (ids.find(m) != ids.end()) { 
        output_text += "ID" + std::to_string(ids[m]) + " "; 
       } 
       else { 
        // not found 
        ids[m] = counter; 
        output_text += "ID" + std::to_string(counter++) + " "; 
       } 
      } 
     } 
     else 
     { 
      output_text += m; 
     } 
    }; 

    std::regex re("\\b\\w*\\b"); 
    std::sregex_token_iterator 
     begin(text.begin(), text.end(), re, { -1, 0 }), 
     end; 
    std::for_each(begin, end, callback); 
    return output_text; 
}