文本查询程序（c++）set,vector,map容器实现

#include<iostream>

#include<fstream>

#include<sstream>

#include<string>

#include<vector>

#include<map>

#include<set>

using namespace std;

class TextQuery{

public:

 typedef vector<string>::size_type line_no;

 void read_file(ifstream &is)

 {

  store_file(is);

  build_map();

 }

 set<line_no>  run_query(const string&) const;

 string  text_line(line_no) const;

private:

 void store_file(ifstream&);

 void build_map();

 vector<string>lines_of_text;

 map<string,set<line_no> >word_map;

};

string make_plural(size_t ctr,const string &word,const string &ending)

{

 return (ctr==1)?word:word+ending;

}

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<<")"

   <<file.text_line(*it)<<endl;

 }

}

void TextQuery::store_file(ifstream &is)

{

 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)

 {

  istringstream line(lines_of_text[line_num]);

  string word;

  while(line>>word)

   word_map[word].insert(line_num);

 }

}

set<TextQuery::line_no> TextQuery::run_query(const 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>();

 else

  return loc->second;

}

string TextQuery::text_line(line_no line)const

{

 if(line<lines_of_text.size())

  return lines_of_text[line];

 else

  cout<<"line too big!"<<endl;

}

ifstream& open_file(ifstream &in,const string &file)

{

 in.close();

 in.clear();

 in.open(file.c_str());

 return in;

}

   

int main(int argc,char **argv)

{

 ifstream infile;

 if(!open_file(infile,"f:\\file.txt"))

 {

  cout<<"no input file!"<<endl;

 }

 TextQuery tq;

 tq.read_file(infile);

 while(true)

 {

  cout<<"enter 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);

 }

 return 0;

}