正则表达式替换回调在c ++ 11？ [英] regex replace with callback in c++11?

问题描述

有一个正则表达式替换的函数，它会将匹配项发送给用户函数，然后替换返回值：

Is there a function of regex replacement that will send the matches to user function and then substitute the return value:

我试过这个方法，不工作：

I've tried this method, but it obviously doesn't work:

cout << regex_replace("my values are 9, 19", regex("\d+"), my_callback);

和功能：

std::string my_callback(std::string &m) {
  int int_m = atoi(m.c_str());
  return std::to_string(int_m + 1);
}

，结果应该是： ，20

我的意思是类似的工作模式像php的 preg_replace_callback 或python的 re.sub（pattern，callback，subject）

I mean similar mode of working like php's preg_replace_callback or python's re.sub(pattern, callback, subject)

我的意思是最新的4.9 gcc， boost。

And I mean the latest 4.9 gcc, that is capable of regex without boost.

推荐答案

我想要这种函数，不喜欢使用boost的答案。本杰明的答案的问题是它提供了所有的标记。这意味着您不知道哪个令牌是匹配项，它不允许您使用捕获组。这样做：

I wanted this kind of function and didn't like the answer "use boost". The problem with Benjamin's answer is it provides all the tokens. This means you don't know which token is a match and it doesn't let you use capture groups. This does:

// clang++ -std=c++11 -stdlib=libc++ -o test test.cpp
#include <cstdlib>
#include <iostream>
#include <string>
#include <regex>

namespace std
{

template<class BidirIt, class Traits, class CharT, class UnaryFunction>
std::basic_string<CharT> regex_replace(BidirIt first, BidirIt last,
    const std::basic_regex<CharT,Traits>& re, UnaryFunction f)
{
    std::basic_string<CharT> s;

    typename std::match_results<BidirIt>::difference_type
        positionOfLastMatch = 0;
    auto endOfLastMatch = first;

    auto callback = [&](const std::match_results<BidirIt>& match)
    {
        auto positionOfThisMatch = match.position(0);
        auto diff = positionOfThisMatch - positionOfLastMatch;

        auto startOfThisMatch = endOfLastMatch;
        std::advance(startOfThisMatch, diff);

        s.append(endOfLastMatch, startOfThisMatch);
        s.append(f(match));

        auto lengthOfMatch = match.length(0);

        positionOfLastMatch = positionOfThisMatch + lengthOfMatch;

        endOfLastMatch = startOfThisMatch;
        std::advance(endOfLastMatch, lengthOfMatch);
    };

    std::sregex_iterator begin(first, last, re), end;
    std::for_each(begin, end, callback);

    s.append(endOfLastMatch, last);

    return s;
}

template<class Traits, class CharT, class UnaryFunction>
std::string regex_replace(const std::string& s,
    const std::basic_regex<CharT,Traits>& re, UnaryFunction f)
{
    return regex_replace(s.cbegin(), s.cend(), re, f);
}

} // namespace std

using namespace std;

std::string my_callback(const std::smatch& m) {
  int int_m = atoi(m.str(0).c_str());
  return std::to_string(int_m + 1);
}

int main(int argc, char *argv[])
{
    cout << regex_replace("my values are 9, 19", regex("\\d+"),
        my_callback) << endl;

    cout << regex_replace("my values are 9, 19", regex("\\d+"),
        [](const std::smatch& m){
            int int_m = atoi(m.str(0).c_str());
            return std::to_string(int_m + 1);
        }
    ) << endl;

    return 0;
}

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