hashed.cpp

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/* Boost.MultiIndex example of use of hashed 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/hashed_index.hpp>
#include <boost/multi_index/member.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/tokenizer.hpp>
#include <iomanip>
#include <iostream>
#include <string>

using boost::multi_index_container;
using namespace boost::multi_index;

/* word_counter keeps the ocurrences of words inserted. A hashed
 * index allows for fast checking of preexisting entries.
 */

struct word_counter_entry
{
  std::string  word;
  unsigned int occurrences;

  word_counter_entry(std::string word_):word(word_),occurrences(0){}
};

/* see Compiler specifics: Use of member_offset for info on
 * BOOST_MULTI_INDEX_MEMBER
 */

typedef multi_index_container<
  word_counter_entry,
  indexed_by<
    ordered_non_unique<
      BOOST_MULTI_INDEX_MEMBER(word_counter_entry,unsigned int,occurrences),
      std::greater<unsigned int> /* sorted beginning with most frequent */
    >,
    hashed_unique<
      BOOST_MULTI_INDEX_MEMBER(word_counter_entry,std::string,word)
    >
  >
> word_counter;

/* utilities */

template<typename T>
struct increment
{
  void operator()(T& x)const{++x;}
};

typedef boost::tokenizer<boost::char_separator<char> > text_tokenizer;

int main()
{
  /* boostinspect:noascii */

  std::string text=
    "En un lugar de la Mancha, de cuyo nombre no quiero acordarme, no ha "
    "mucho tiempo que viv韆 un hidalgo de los de lanza en astillero, adarga "
    "antigua, roc韓 flaco y galgo corredor. Una olla de algo m醩 vaca que "
    "carnero, salpic髇 las m醩 noches, duelos y quebrantos los s醔ados, "
    "lantejas los viernes, alg鷑 palomino de a馻didura los domingos, "
    "consum韆n las tres partes de su hacienda. El resto della conclu韆n sayo "
    "de velarte, calzas de velludo para las fiestas, con sus pantuflos de lo "
    "mesmo, y los d韆s de entresemana se honraba con su vellor