concord.cpp

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#include <iostream>
#include <list>
#include <locale>
#include <map>
#include <string>
 
#include <examples.h>
 
 
// Split a line of text into words.
void split (const std::string& text, const std::string& separators,
            std::list<std::string,std::allocator<std::string> > &words)
{
 
    const std::string::size_type n = text.length ();
    std::string::size_type start   = text.find_first_not_of (separators);
 
    while (start < n) {
        std::string::size_type stop = text.find_first_of (separators, start);
        if (stop > n) stop = n;
        words.push_back (text.substr (start, stop-start));
        start = text.find_first_not_of (separators, stop+1);
    }
}
 
 
class concordance
{
    typedef std::multimap<std::string,int,
                          std::less<std::string>,
                          std::allocator<std::pair<const std::string,
                                                   int> > > wordDictType;
public:
    void addWord (std::string, int);
    void readText (std::istream &);
    void printConcordance (std::ostream &);
private:
    wordDictType wordMap;
};
 
 
void concordance::addWord (std::string word, int line)
{
    // First get range of entries with same key.
    wordDictType::iterator low = wordMap.lower_bound (word);
    wordDictType::iterator high = wordMap.upper_bound (word);
 
    // Loop over entires, see if any match current line.
    for ( ; low != high; ++low)
        if ( (*low).second == line)
            return;
 
    // Didn't occur, add now.
    wordMap.insert (wordDictType::value_type (word, line));
}
 
 
void allLower (std::string &s)
{
    for (std::size_t i = 0; i < s.size (); i++)
        if ((std::isupper)(s [i], std::locale ()))
            s [i] = (std::tolower)(s [i], std::locale ());
}
 
 
void concordance::readText (std::istream & in)
{
    std::string line;
 
    for (int i = 1; std::getline (in, line); i++) {
        allLower (line);
        std::list<std::string, std::allocator<std::string> > words;
        split (line, " , .;:", words);
        std::list<std::string, std::allocator<std::string> >::iterator wptr;
        for (wptr = words.begin (); wptr != words.end (); ++wptr)
            addWord (*wptr, i);
    }
}
 
 
void concordance::printConcordance (std::ostream & out)
{
    std::string            lastword ("");
    wordDictType::iterator pairPtr;
    wordDictType::iterator stop = wordMap.end ();
 
    for (pairPtr = wordMap.begin (); pairPtr != stop; ++pairPtr)
        // If word is same as previous, just print line number.
        if (lastword == (*pairPtr).first)
            out << ' ' << (*pairPtr).second;
        else {
            // First entry of word.
            lastword = (*pairPtr).first;
            std::cout << '\n' << lastword << ": " << (*pairPtr).second;
        }
    std::cout << '\n';
}
 
 
int main ()
{
    std::cout << "Concordance sample program, from Chapter 7\n"
              << "Enter text, then end-of-file:\n";
 
    concordance words;
 
    words.readText (std::cin);    
    words.printConcordance (std::cout);
 
    std::cout << "End of concordance sample program\n";
 
    return 0;
}