<<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;}