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/*
Copyright (c) Marshall Clow 2010-2012.
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)
For more information, see http://www.boost.org
*/
#ifndef BOOST_ALGORITHM_SEARCH_DETAIL_BM_TRAITS_HPP
#define BOOST_ALGORITHM_SEARCH_DETAIL_BM_TRAITS_HPP
#include <climits> // for CHAR_BIT
#include <vector>
#include <iterator> // for std::iterator_traits
#include <boost/type_traits/make_unsigned.hpp>
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/remove_pointer.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/array.hpp>
#include <boost/tr1/tr1/unordered_map>
#include <boost/algorithm/searching/detail/debugging.hpp>
namespace boost { namespace algorithm { namespace detail {
//
// Default implementations of the skip tables for B-M and B-M-H
//
template<typename key_type, typename value_type, bool /*useArray*/> class skip_table;
// General case for data searching other than bytes; use a map
template<typename key_type, typename value_type>
class skip_table<key_type, value_type, false> {
private:
typedef std::tr1::unordered_map<key_type, value_type> skip_map;
const value_type k_default_value;
skip_map skip_;
public:
skip_table ( std::size_t patSize, value_type default_value )
: k_default_value ( default_value ), skip_ ( patSize ) {}
void insert ( key_type key, value_type val ) {
skip_ [ key ] = val; // Would skip_.insert (val) be better here?
}
value_type operator [] ( key_type key ) const {
typename skip_map::const_iterator it = skip_.find ( key );
return it == skip_.end () ? k_default_value : it->second;
}
void PrintSkipTable () const {
std::cout << "BM(H) Skip Table <unordered_map>:" << std::endl;
for ( typename skip_map::const_iterator it = skip_.begin (); it != skip_.end (); ++it )
if ( it->second != k_default_value )
std::cout << " " << it->first << ": " << it->second << std::endl;
std::cout << std::endl;
}
};
// Special case small numeric values; use an array
template<typename key_type, typename value_type>
class skip_table<key_type, value_type, true> {
private:
typedef typename boost::make_unsigned<key_type>::type unsigned_key_type;
typedef boost::array<value_type, 1U << (CHAR_BIT * sizeof(key_type))> skip_map;
skip_map skip_;
const value_type k_default_value;
public:
skip_table ( std::size_t patSize, value_type default_value ) : k_default_value ( default_value ) {
std::fill_n ( skip_.begin(), skip_.size(), default_value );
}
void insert ( key_type key, value_type val ) {
skip_ [ static_cast<unsigned_key_type> ( key ) ] = val;
}
value_type operator [] ( key_type key ) const {
return skip_ [ static_cast<unsigned_key_type> ( key ) ];
}
void PrintSkipTable () const {
std::cout << "BM(H) Skip Table <boost:array>:" << std::endl;
for ( typename skip_map::const_iterator it = skip_.begin (); it != skip_.end (); ++it )
if ( *it != k_default_value )
std::cout << " " << std::distance (skip_.begin (), it) << ": " << *it << std::endl;
std::cout << std::endl;
}
};
template<typename Iterator>
struct BM_traits {
typedef typename std::iterator_traits<Iterator>::difference_type value_type;
typedef typename std::iterator_traits<Iterator>::value_type key_type;
typedef boost::algorithm::detail::skip_table<key_type, value_type,
boost::is_integral<key_type>::value && (sizeof(key_type)==1)> skip_table_t;
};
}}} // namespaces
#endif // BOOST_ALGORITHM_SEARCH_DETAIL_BM_TRAITS_HPP
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