cpp primer 验证 p325页 文本查讯程序

头文件：TextQuery.h

#pragma once
#include <string>
#include <vector>
#include <map>
#include <set>
#include <fstream>
using namespace std;
//文本查讯类
class TextQuery
{
public:
	typedef std::vector<std::string>::size_type line_no;
	//接口
	void read_file(std::ifstream& is)
	{
		store_file(is);
		build_map();
	}
	std::set<line_no> run_query(const std::string&) const;
	std::string text_line(line_no) const;
private:
	void store_file(std::ifstream &);//store input file
	void build_map();
	std::vector<std::string> lines_of_text;
	std::map<std::string, std::set<line_no> >word_map;
};

文件：TextQuery.cpp

#include "TextQuery.h"
#include<sstream>
void TextQuery::store_file(std::ifstream& is )
{
	string text_line;
	while (getline(is, text_line))
	{
		lines_of_text.push_back(text_line);
	}
}
void TextQuery::build_map()
{
	for (line_no line_num = 0;
	        line_num != lines_of_text.size(); ++line_num)
	{
		istringstream line(lines_of_text[line_num]);
		string word;
		while (line >> word)
		{
			word_map[word].insert(line_num);
		}
	}
}
std::set<TextQuery::line_no> TextQuery::run_query( const std::string& query_word ) const
{
	map<string, set<line_no> >::const_iterator loc = word_map.find(query_word);
	if (loc == word_map.end())
	{
		return set<line_no>();  //no fount return empty set
	}
	else
	{
		return loc->second;
	}
}
std::string TextQuery::text_line( line_no line ) const
{
	if (lines_of_text.size())
	{
		return lines_of_text[line];
	}
	throw std::out_of_range("line number out of range");
}

主函数文件：main.cpp

#include "TextQuery.h"
#include <iostream>
#include <fstream>
using namespace std;

//函数申明
void print_results(const set<TextQuery::line_no> &locs,
                   const string& sought, const TextQuery& file);
string make_plural(size_t ctr, const string& word, const string& ending);
ifstream& open_file(ifstream& in, const string& file);
int main(int argc, char** argv)
{
	ifstream infile;
	if (argc < 2 || !open_file(infile, argv[1]))
	{
		cerr << "No input file!" << endl;
		return  -1;//EXIT_FAILURE;
	}
	TextQuery tq;
	tq.read_file(infile);
	while (true)
	{
		cout << "Enter a word to look for, or q to quit:";
		string s;
		cin >> s;
		if (!cin || s == "q")
		{
			break;
		}
		set<TextQuery::line_no> locs = tq.run_query(s);
		print_results(locs, s, tq);
	}
}
//print_results
void print_results(const set<TextQuery::line_no> &locs,
                   const string& sought, const TextQuery& file)
{
	typedef set<TextQuery::line_no> line_nums;
	line_nums::size_type size = locs.size();
	cout << "/n" << sought << "  occurs "
	     << size << " "
	     << make_plural(size, "time", "s") << endl;
	line_nums::const_iterator it = locs.begin();
	for ( ; it != locs.end(); ++it)
	{
		cout << "/t(line"
		     << (*it) + 1 << ") " //转化为以1开始的通用形式
		     << file.text_line(*it) << endl;
	}
}
string make_plural(size_t ctr, const string& word, const string& ending)
{
	return (ctr <= 1) ? word : word + ending; //make_plural(wc, "word ", "s ")当输入中文本中
	//word数大于一是在word后加s，为words为word的复数！
}
ifstream& open_file(ifstream& in, const string& file)
{
	in.close();
	in.clear();
	in.open(file.c_str());
	return in;
}