C++ regex: Conditional replace

Question

I want to replace with a regular expression all the words in the text that are not in the dictionary on the unique identifier. How I can do it? Maybe using callback function?

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

Use 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;
}