tuple类型的单词查询例子

17.3 重写前面的TextQuery程序，使用tuple代替QueryResult类。

TextQuery.h

#ifndef TEXTQUERY_H

#define TEXTQUERY_H

#include<iostream>

#include<string>

#include<fstream>

#include<vector>

#include<memory>

#include<map>

#include<set>

#include<new>

#include<tuple>

#include"DebugDelete.h"

using namespace std;

class QueryResult;

class TextQuery

{

public:

    using line_no=vector<string>::size_type;

    TextQuery(ifstream&);

    tuple<string,shared_ptr<set<TextQuery::line_no>>,shared_ptr<vector<string>>> query(const string&) const;

    ~TextQuery()

    {

        //DebugDelete()(new vector<string>);

        cout<<"destructing...."<<endl;

    }

private:

    shared_ptr<vector<string>> file;

    map<string,shared_ptr<set<line_no>>> wm;

};

#endif // TEXTQUERY_H

TextQuery.cpp

#include"TextQuery.h"

#include<tuple>

#include<sstream>

TextQuery::TextQuery(ifstream& is):file(new vector<string>,DebugDelete())

{

    string text;

    while(getline(is,text))

    {

        file->push_back(text);

        int n=file->size()-1;

        string word;

        istringstream line(text);

        while(line>>word)

        {

            auto &lines=wm[word];

            if(!lines)

                lines.reset(new set<line_no>);

            lines->insert(n);

        }

    }

}



tuple<string,shared_ptr<set<TextQuery::line_no>>,shared_ptr<vector<string>>>

TextQuery::query(const string& sought) const

{

    static shared_ptr<set<line_no>> nodata(new set<line_no>);

    auto loc=wm.find(sought);

    if(loc!=wm.end())

        return make_tuple(sought,loc->second,file);

    else

        return make_tuple(sought,nodata,file);

}

main.cpp

/*

 * This file contains code from "C++ Primer, Fifth Edition", by Stanley B.

 * Lippman, Josee Lajoie, and Barbara E. Moo, and is covered under the

 * copyright and warranty notices given in that book:

 *

 * "Copyright (c) 2013 by Objectwrite, Inc., Josee Lajoie, and Barbara E. Moo."

 *

 *

 * "The authors and publisher have taken care in the preparation of this book,

 * but make no expressed or implied warranty of any kind and assume no

 * responsibility for errors or omissions. No liability is assumed for

 * incidental or consequential damages in connection with or arising out of the

 * use of the information or programs contained herein."

 *

 * Permission is granted for this code to be used for educational purposes in

 * association with the book, given proper citation if and when posted or

 * reproduced.Any commercial use of this code requires the explicit written

 * permission of the publisher, Addison-Wesley Professional, a division of

 * Pearson Education, Inc. Send your request for permission, stating clearly

 * what code you would like to use, and in what specific way, to the following

 * address:

 *

 *     Pearson Education, Inc.

 *     Rights and Permissions Department

 *     One Lake Street

 *     Upper Saddle River, NJ  07458

 *     Fax: (201) 236-3290

*/



#include <string>

using std::string;



#include <fstream>

using std::ifstream;



#include <iostream>

using std::cin; using std::cout; using std::cerr;

using std::endl;



#include <cstdlib>  // for EXIT_FAILURE



#include "TextQuery.h"

#include<tuple>

ostream &print(ostream &os,const tuple<string,shared_ptr<set<TextQuery::line_no>>,shared_ptr<vector<string>>> &qr)

{

    os<<get<0>(qr)<<" occurs "<<get<1>(qr)->size()<<" times "<<endl;

    for(auto num:*get<1>(qr))

        os<<"\t(line "<<num+1<<" ) "

        <<(*get<2>(qr))[num]<<endl;

    return os;

}

void runQueries(ifstream &infile)

{

    // infile is an ifstream that is the file we want to query

    TextQuery tq(infile);  // store the file and build the query map

    // iterate with the user: prompt for a word to find and print results

    while (true) {

        cout << "enter word to look for, or q to quit: ";

        string s;

        // stop if we hit end-of-file on the input or if a 'q' is entered

        if (!(cin >> s) || s == "q") break;

        // run the query and print the results

        print(cout, tq.query(s)) << endl;

    }

}



// program takes single argument specifying the file to query

int main(int argc, char **argv)

{

    // open the file from which user will query words

    ifstream infile;

    // open returns void, so we use the comma operator XREF(commaOp)

    // to check the state of infile after the open

    if (argc < 2 || !(infile.open(argv[1]), infile)) {

        cerr << "No input file!" << endl;

        return EXIT_FAILURE;

    }

    runQueries(infile);

    return 0;

}

DebugDelete.h

#include<iostream>

#include<new>

using namespace std;



class DebugDelete

{

public:

    DebugDelete(ostream &s=cerr):os(s) {}

    template <typename T>

    void operator()(T *p) const

    {

        os<<"deleting shared_ptr "<<endl;

        delete p;

    }

private:

    ostream &os;

};