code/c/C++Primer/ch12/textquery.h

#ifndef TEXTQUERY_H
#define TEXTQUERY_H


#include <algorithm>
#include <fstream>
#include <sstream>
#include <vector>
#include <string>
#include <memory>
#include <map>
#include <set>

class QueryResult;

class TextQuery {
public:
  using LineNo = std::vector<std::string>::size_type;

  TextQuery() = default;
  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<LineNo>>> wm;
};

TextQuery::TextQuery(std::ifstream &ifs) : file(new std::vector<std::string>) {
  if (ifs) {
    LineNo n(0);
    for (std::string line; getline(ifs, line); ++n) {
      file->push_back(line);
      std::istringstream iss(line);
      for (std::string text, word; iss >> text; word.clear()) {
        std::remove_copy_if(begin(text), end(text), back_inserter(word), ispunct);
        auto &lines = wm[word];
        if (!lines)
          lines.reset(new std::set<LineNo>);
        lines->insert(n);
      }
    }
  } else
      throw std::runtime_error("cannot read file from fstream");
}


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

private:
  std::string sought;
  std::shared_ptr<std::set<TextQuery::LineNo>> lines;
  std::shared_ptr<std::vector<std::string>> file;
};

std::ostream &print(std::ostream &os, const QueryResult &qr) {
  os << "\"" << qr.sought << "\" is in " << qr.lines->size() << " lines.\n";
  for (auto n : *qr.lines)
    os << "\tno." << n + 1 << "\t: " << *(qr.file->begin() + n) << "\n";
  return os;
}

QueryResult TextQuery::query(const std::string &s) const {
  static std::shared_ptr<std::set<LineNo>> nodata(new std::set<LineNo>);
  auto loc = wm.find(s);
  if (loc == wm.end())
    return QueryResult(s, nodata, file);
  else
    return QueryResult(s, wm.at(s), file);
}


#endif // !TEXTQUERY_H