ex12_27_30.cpp

//
//  ex12_27.cpp
//  Exercise 12.27
//
//  Created by pezy on 12/31/14.
//  Copyright (c) 2014 pezy. All rights reserved.
//
//  The TextQuery and QueryResult classes use only capabilities that we have
//  already covered.
//  Without looking ahead, write your own versions of these classes.

#include "ex12_27_30.h"
#include <sstream>
#include <algorithm>
#include <iterator>

TextQuery::TextQuery(std::ifstream& ifs) : input(new vector<string>)
{
    LineNo lineNo{0};
    for (string line; std::getline(ifs, line); ++lineNo) {
        input->push_back(line);
        std::istringstream line_stream(line);
        for (string text, word; line_stream >> text; word.clear()) {
            // avoid read a word followed by punctuation(such as: word, )
            std::remove_copy_if(text.begin(), text.end(),
                                std::back_inserter(word), ispunct);
            // use reference avoid count of shared_ptr add.
            auto& nos = result[word];
            if (!nos) nos.reset(new std::set<LineNo>);
            nos->insert(lineNo);
        }
    }
}

QueryResult TextQuery::query(const string& str) const
{
    // use static just allocate once.
    static shared_ptr<std::set<LineNo>> nodate(new std::set<LineNo>);
    auto found = result.find(str);
    if (found == result.end())
        return QueryResult(str, nodate, input);
    else
        return QueryResult(str, found->second, input);
}

std::ostream& print(std::ostream& out, const QueryResult& qr)
{
    out << qr.word << " occurs " << qr.nos->size()
        << (qr.nos->size() > 1 ? " times" : " time") << std::endl;
    for (auto i : *qr.nos)
        out << "\t(line " << i + 1 << ") " << qr.input->at(i) << std::endl;
    return out;
}