Using boost::tokenizer with string delimiters

问题

I've been looking boost::tokenizer, and I've found that the documentation is very thin. Is it possible to make it tokenize a string such as "dolphin--monkey--baboon" and make every word a token, as well as every double dash a token? From the examples I've only seen single character delimiters being allowed. Is the library not advanced enough for more complicated delimiters?

回答1:

It looks like you will need to write your own TokenizerFunction to do what you want.

回答2:

using iter_split allows you to use multiple character tokens. The code below would produce the following:

dolphin
mon-key
baboon

#include <iostream>
#include <boost/foreach.hpp>
#include <boost/algorithm/string.hpp>
#include <boost/algorithm/string/iter_find.hpp>

    // code starts here
    std::string s = "dolphin--mon-key--baboon";
    std::list<std::string> stringList;
    boost::iter_split(stringList, s, boost::first_finder("--"));

    BOOST_FOREACH(std::string token, stringList)
    {    
        std::cout << token << '\n';  ;
    }

回答3:

I know the theme is quite old, but it is shown in the top links in google when I search "boost tokenizer by string"

so I will add my variant of TokenizerFunction, just in case:

class FindStrTFunc
{
public:
    FindStrTFunc() : m_str(g_dataSeparator)
    {
    }

    bool operator()(std::string::const_iterator& next,
        const std::string::const_iterator& end, std::string& tok) const
    {
        if (next == end)
        {
            return false;
        }
        const std::string::const_iterator foundToken =
            std::search(next, end, m_str.begin(), m_str.end());
        tok.assign(next, foundToken);
        next = (foundToken == end) ? end : foundToken + m_str.size();
        return true;
    }

    void reset()
    {
    }

private:
    std::string m_str;
};

after we can create

boost::tokenizer<FindStrTFunc> tok("some input...some other input");

and use, like a usual boost tokenizer

回答4:

One option is to try boost::regex. Not sure of the performance compared to a custom tokenizer.

std::string s = "dolphin--monkey--baboon";

boost::regex re("[a-z|A-Z]+|--");
boost::sregex_token_iterator iter(s.begin(), s.end() , re, 0);
boost::sregex_token_iterator end_iter;

while(iter != end_iter)
{
    std::cout << *iter << '\n';
    ++iter;
}

来源：https://stackoverflow.com/questions/1252224/using-boosttokenizer-with-string-delimiters

标签

c++

string

boost

tokenize