<<c++ primer>>文本查询程序

#ifndef _TEXTQUERY_H
#define _TEXTQUERY_H

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

class TextQuery
{
public:
	typedef std::vector<std::string>::size_type line_no;
	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&);
	void build_map();
	std::vector<std::string> lines_of_text;
	std::map<std::string,std::set<line_no>> word_map;
};

void TextQuery::store_file(std::ifstream &is)
{
	std::string textline;
	while(getline(is,textline))
	{
		lines_of_text.push_back(textline);
	}
}

void  TextQuery::build_map()
{
	for(line_no line_num=0;line_num!=lines_of_text.size();++line_num)
	{
		std::istringstream line(lines_of_text[line_num]);
		std::string word;
		while(line>>word)
		{
			int index1=word.find(",");
			int index2=word.find(".");
			int index=index1>index2 ? index1 : index2;
			if(index!=-1)
			{
				word_map[word.substr(0,index)].insert(line_num);
			}
			else
			{
				word_map[word].insert(line_num);
			}
		}
	}
}

std::set<TextQuery::line_no> TextQuery::run_query(const std::string& query_word) const
{
	std::map<std::string,std::set<line_no>>::const_iterator loc=word_map.find(query_word);
	if(loc==word_map.end())
	{
		return std::set<line_no>();
	}
	else
	{
		return loc->second;
	}
}

std::string TextQuery::text_line(line_no line) const
{
	if(line<lines_of_text.size())
	{
		return lines_of_text[line];
	}
	else
	{
		throw std::out_of_range("line number out of range");
	}
}
#endif

// test.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <set>
#include "TextQuery.h"
void print_results(const std::set<TextQuery::line_no>& locs, const std::string& sought,const TextQuery& file);

#define FN "cjc.txt"

int main(int argc,char **argv)
{
	std::ifstream infile(FN,std::ios::in);
	if(!infile)
	{
		std::cerr<<"No input file!"<<std::endl;
		return EXIT_FAILURE;
	}
	TextQuery tq;
	tq.read_file(infile);

	while(true)
	{
		std::cout<<"enter word to look for, or q to quit:";
		std::string s;
		std::cin>>s;
		std::cin.get();

		if(!std::cin || s=="q")
		{
			break;
		}

		std::set<TextQuery::line_no> locs=tq.run_query(s);
		print_results(locs,s,tq);
	}

	system("pause");
	return 0;
}

///////////////////////////////////////////////////////////////////////////////////////
std::string make_plural(int size,std::string str1,std::string str2)
{
	if(size>1)
	{
		return str1+str2;
	}
	else
	{
		return str1;
	}
}

void print_results(const std::set<TextQuery::line_no>& locs, const std::string& sought,const TextQuery& file)
{
	typedef std::set<TextQuery::line_no> line_nums;
	line_nums::size_type size=locs.size();

	std::cout<<sought<<" occurs "<<size<<" "
					<<make_plural(size, "time","s")<<std::endl;

	line_nums::const_iterator it=locs.begin();

	for(;it!=locs.end();++it)
	{
		std::cout<<"\t(line "
						<<(*it)+1<<") "
						<<file.text_line(*it)<<std::endl;
	}
	std::cout<<"**********************************************"<<std::endl;
}