textquery.h

#include<iostream>
#include<sstream>
#include<fstream>

#include<string>
#include<vector>
#include<map>
#include<set>

#include<memory>


class QueryResult;
class TextQuery;
std::string make_plural(size_t ctr, const std::string &word, const std::string &ending);


// TextQuery类
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构造函数
TextQuery::TextQuery(std::ifstream &is): file(new std::vector<std::string>)
{
    std::string text;
    while (getline(is, text)) {
        file->push_back(text);
        int n = file->size() - 1;
        std::istringstream line(text);
        std::string word;
        while (line >> word) {
            auto &lines = wm[word];
            if (!lines)
                lines.reset(new std::set<line_no>);
            lines->insert(n);
        }
    }
}


// QueryResult类
class QueryResult {
friend std::ostream& print(std::ostream&, const QueryResult&);
public:
    QueryResult(
            std::string s,
            std::shared_ptr<std::set<TextQuery::line_no>> p,
            std::shared_ptr<std::vector<std::string>> f
        ): sought(s), lines(p), file(f) { }
private:
    std::string sought;
    std::shared_ptr<std::set<TextQuery::line_no>> lines;
    std::shared_ptr<std::vector<std::string>> file;
};


// query函数
QueryResult TextQuery::query(const std::string &sought) const
{
    static std::shared_ptr<std::set<line_no>> nodata(new std::set<line_no>);
    auto loc = wm.find(sought);
    if (loc == wm.end())
        return QueryResult(sought, nodata, file);
    else
        return QueryResult(sought, loc->second, file);
}


// 打印结果
std::ostream &print(std::ostream & os, const QueryResult &qr)
{

    os << qr.sought << " occurs " << qr.lines->size() << " " << make_plural(qr.lines->size(), "time", "s") << std::endl;
    for (auto num : *qr.lines)
        os << "\t(line" << num + 1 << ") " << *(qr.file->begin() + num) << std::endl;
}


std::string make_plural(size_t ctr, const std::string &word, const std::string &ending)
{
    return (ctr > 1) ? word+ending : word;
}


// 使用TextQuery类
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));
    }
}