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/* 
 * Copyright (c) 2017, Intel Corporation 
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met: 
 * 
 *  * Redistributions of source code must retain the above copyright notice, 
 *    this list of conditions and the following disclaimer. 
 *  * Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *  * Neither the name of Intel Corporation nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE. 
 */ 
 
/** 
 * \file 
 * \brief Hashing utility functions. 
 */ 
 
#ifndef UTIL_HASH_DYNAMIC_BITSET_H 
#define UTIL_HASH_DYNAMIC_BITSET_H 
 
#include "hash.h" 
 
#include <boost/dynamic_bitset.hpp> 
 
#include <iterator> 
 
namespace ue2 { 
 
/** 
 * \brief An output iterator which calculates the combined hash of all elements 
 * written to it. 
 * 
 * The location to output the hash is provided to the constructor and should 
 * already be zero initialised. 
 */ 
struct hash_output_it { 
    using value_type = void; 
    using difference_type = ptrdiff_t; 
    using pointer = void *; 
    using reference = void; 
    using iterator_category = std::output_iterator_tag; 
 
    hash_output_it(size_t *hash_out = nullptr) : out(hash_out) {} 
    hash_output_it &operator++() { 
        return *this; 
    } 
    hash_output_it &operator++(int) { 
        return *this; 
    } 
 
    struct deref_proxy { 
        deref_proxy(size_t *hash_out) : out(hash_out) {} 
 
        template<typename T> 
        void operator=(const T &val) const { 
            hash_combine(*out, val); 
        } 
 
    private: 
        size_t *out; /* output location of the owning iterator */ 
    }; 
 
    deref_proxy operator*() { return {out}; } 
 
private: 
    size_t *out; /* location to output the hashes to */ 
}; 
 
/* Function object for hashing a dynamic bitset */ 
struct hash_dynamic_bitset { 
    size_t operator()(const boost::dynamic_bitset<> &bs) const { 
        size_t rv = 0; 
        to_block_range(bs, hash_output_it(&rv)); 
        return rv; 
    } 
}; 
 
} // namespace ue2 
 
#endif