libs/multi_index/example/sequenced.cpp

/* Boost.MultiIndex example of use of sequenced indices.
 *
 * Copyright 2003-2008 Joaquin M Lopez Munoz.
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 *
 * See http://www.boost.org/libs/multi_index for library home page.
 */
#if !defined(NDEBUG)
#define BOOST_MULTI_INDEX_ENABLE_INVARIANT_CHECKING
#define BOOST_MULTI_INDEX_ENABLE_SAFE_MODE
#endif
#include <boost/multi_index_container.hpp>
#include <boost/multi_index/identity.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index/sequenced_index.hpp>
#include <boost/tokenizer.hpp>
#include <algorithm>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <string>
using boost::multi_index_container;
using namespace boost::multi_index;
/* text_container holds words as inserted and also keep them indexed
 * by dictionary order.
 */
typedef multi_index_container<
  std::string,
  indexed_by<
    sequenced<>,
    ordered_non_unique<identity<std::string> >
  >
> text_container;
/* ordered index */
typedef nth_index<text_container,1>::type ordered_text;
typedef boost::tokenizer<boost::char_separator<char> > text_tokenizer;
int main()
{
  std::string text=
    "Alice was beginning to get very tired of sitting by her sister on the "
    "bank, and of having nothing to do: once or twice she had peeped into the "
    "book her sister was reading, but it had no pictures or conversations in "
    "it, 'and what is the use of a book,' thought Alice 'without pictures or "
    "conversation?'";
  /* feed the text into the container */
  text_container tc;
  text_tokenizer tok(text,boost::char_separator<char>(" \t\n.,;:!?'\"-"));
  std::copy(tok.begin(),tok.end(),std::back_inserter(tc));
  /* list all words in alphabetical order along with their number
   * of occurrences
   */
  ordered_text& ot=get<1>(tc);
  for(ordered_text::iterator it=ot.begin();it!=ot.end();){
    std::cout<<std::left<<std::setw(14)<<*it<<":";  /* print the word */
    ordered_text::iterator it2=ot.upper_bound(*it); /* jump to next   */
    std::cout<<std::right<<std::setw(3)   /* and compute the distance */
             <<std::distance(it,it2)<<" times"<<std::endl;
    it=it2;
  }
  /* reverse the text and print it out */
  tc.reverse();
  std::cout<<std::endl;
  std::copy(
    tc.begin(),tc.end(),std::ostream_iterator<std::string>(std::cout," "));
  std::cout<<std::endl;
  tc.reverse(); /* undo */
  /* delete most common English words and print the result */
  std::string common_words[]=
    {"the","of","and","a","to","in","is","you","that","it",
     "he","for","was","on","are","as","with","his","they","at"};
  for(std::size_t n=0;n<sizeof(common_words)/sizeof(common_words[0]);++n){
    ot.erase(common_words[n]);
  }
  std::cout<<std::endl;
  std::copy(
    tc.begin(),tc.end(),std::ostream_iterator<std::string>(std::cout," "));
  std::cout<<std::endl;
  return 0;
}