regex, C++ (vc++) - rextester

Language: Layout:

//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x64

#include <iostream>
#include <string>
#include <regex>
#include <map>
#include <vector>
#include <sstream>
#include <iomanip>

// if the line contains just a single integer of up to five digits, it is a query number
bool is_query_number( const std::string& line )
{
    // beginning of string, zero or more white space, one to five decimal digits,
    // zero or more white space, end of string
    static const std::regex number_re( "^\\s*\\d{1,5}\\s*$" ) ;

return std::regex_match( line, number_re ) ;
}

// return a vector of alphanumeric tokens in the line
std::vector<std::string> get_tokens( const std::string& line )
{
    static const std::regex words_re( "\\w+" ) ;

std::vector<std::string> result ;

std::sregex_iterator iter( line.begin(), line.end(), words_re ), end ;
    for( ; iter != end ; ++iter ) result.push_back( iter->str() ) ;

return result ;
}

std::map< int, std::vector<std::string> > get_queries( std::istream& stm )
{
    std::map< int, std::vector<std::string> > result ;

int query_number = 0 ; // default initial query number is zero

std::string line ;
    while( std::getline( stm, line ) ) // for each line in the stream
    {
        // if this line contains a new query number, update query_number
        if( is_query_number(line) ) query_number = std::stoi(line) ;

// otherwise add the tokens in the line to the current query
        else for( const auto& tok : get_tokens(line) ) result[query_number].push_back(tok) ;
    }

return result ;
}

int main()
{
   // create some data for testing
   std::istringstream file( "1\n"
                            "seven five one\n"
                            " 2 \n"
                            " three four  nine fifteen \n"
                            "twelve 44 nineteen\n"
                            "3\n"
                            "two one\n"
                            "eleven\n"
                          ) ;

// for( const auto& [ query_number, tokens ] : get_queries(file) )
    for( const auto& pair : get_queries(file) ) // ***
    {
        const auto& query_number = pair.first ; // *** aded
        const auto& tokens = pair.second ;// *** added
        
        std::cout << "query #" << query_number << "  [ " ;
        
        //for( const auto& tok : tokens ) std::cout << std::quoted(tok) << ' ' ;
        for( const auto& tok : tokens ) std::cout << '"' << tok << "\" " ; // ***
        std::cout << "]\n\n" ;
    }
}

Show compiler warnings [ + ] Compiler args [ + ] Show input
Compilation time: 2,66 sec, absolute running time: 0,24 sec, absolute service time: 2,91 sec