12.3.1

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QueryResult.h

#pragma once#include<memory>#include<set>#include<string>#include<vector>class QueryResult {    using line_no = std::vector<std::string>::size_type;public:    QueryResult(std::string s, std::shared_ptr<std::set<line_no>> p,        std::shared_ptr<std::vector<std::string>> f) :        sought(s), lines(p), file(f){}    friend std::ostream &print(std::ostream& os, const QueryResult&qr);private:    std::string sought;    std::shared_ptr<std::set<line_no> > lines;    std::shared_ptr<std::vector<std::string> > file;};

TextQuery.h

#pragma once#include<fstream>#include<string>#include<sstream>#include<vector>#include<memory>#include<map>#include<set>class QueryResult;class TextQuery{public:    using line_no = std::vector<std::string>::size_type;    TextQuery(std::ifstream&);    QueryResult query(const std::string&) const;private:    std::shared_ptr<std::vector<std::string>>  file;    std::map < std::string, std::shared_ptr<std::set<line_no>>>  wm;};

TextQuery.cpp

#include"TextQuery.h"#include"QueryResult.h"TextQuery::TextQuery(std::ifstream& infile) :file(new std::vector<std::string>){    std::string line;    while (getline(infile, line)) {        file->push_back(line);        int n = file->size();        std::istringstream aline(line);        std::string word;        while (aline >> word) {            auto &lines = wm[word];            if (!lines)                lines.reset(new std::set<line_no>);            lines->insert(n);        }    }}QueryResult TextQuery::query(const std::string&sought) const {    static std::shared_ptr<std::set<line_no>> nodate(new std::set<line_no>);    auto loc = wm.find(sought);    if (loc == wm.end()) {        return QueryResult(sought, nodate, file);    }    else    {        return QueryResult(sought, loc->second, file);    }}

Main

#include"TextQuery.h"#include"QueryResult.h"#include<iostream>std::ostream &print(std::ostream& os, const QueryResult&qr) {    os << qr.sought << " occurs " << qr.lines->size() << (qr.lines->size() > 1 ? " times" : " time") << std::endl;    for (auto num : *qr.lines) {        os << "\t(line " << num << ") "<< *(qr.file->begin() + num - 1) << std::endl;    }    return os;}void runQueries(std::ifstream &infile) {    TextQuery tq(infile);    while (true) {        std::cout << "enter word to look for,or q to quit: ";        std::string s;        if (!(std::cin >> s) || s == "q")            break;        print(std::cout, tq.query(s)) << std::endl;    }}int main(){    runQueries(std::ifstream("TXT.txt"));    return 0;}

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