std::regex_token_iterator

std::regex_token_iterator is a read-only LegacyForwardIterator

On construction, it constructs an std::regex_iterator and on every increment it steps through the requested sub-matches from the current match_results, incrementing the underlying std::regex_iterator

The default-constructed std::regex_token_iterator is the end-of-sequence iterator. When a valid std::regex_token_iterator

Just before becoming the end-of-sequence iterator, a std::regex_token_iterator may become a suffix iterator, if the index -1

A typical implementation of std::regex_token_iterator holds the underlying std::regex_iterator, a container (e.g. std::vector < int > ) of the requested submatch indices, the internal counter equal to the index of the submatch, a pointer to std::sub_match, pointing at the current submatch of the current match, and a std::match_results

Type requirements

Specializations

Several specializations for common character sequence types are defined:

Member types

Member functions

Notes

It is the programmer's responsibility to ensure that the std::basic_regex object passed to the iterator's constructor outlives the iterator. Because the iterator stores a std::regex_iterator

Example

#include <algorithm>
#include <fstream>
#include <iostream>
#include <iterator>
#include <regex>
 
int main()
{
    // Tokenization (non-matched fragments)
    // Note that regex is matched only two times; when the third value is obtained
    // the iterator is a suffix iterator.
    const std::string text = "Quick brown fox.";
    const std::regex ws_re("\\s+"); // whitespace
    std::copy(std::sregex_token_iterator(text.begin(), text.end(), ws_re, -1),
              std::sregex_token_iterator(),
              std::ostream_iterator<std::string>(std::cout, "\n"));
 
    std::cout << '\n';
 
    // Iterating the first submatches
    const std::string html = R"(<p><a href="http://google.com">google</a> )"
                             R"(< a HREF ="http://cppreference.com">cppreference</a>\n</p>)";
    const std::regex url_re(R"!!(<\s*A\s+[^>]*href\s*=\s*"([^"]*)")!!", std::regex::icase);
    std::copy(std::sregex_token_iterator(html.begin(), html.end(), url_re, 1),
              std::sregex_token_iterator(),
              std::ostream_iterator<std::string>(std::cout, "\n"));
}

Quick
brown
fox.
 
http://google.com
http://cppreference.com

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

1. ↑ iterator_category was unchanged by the resolution, because changing it to std::input_iterator_tag