HashStream.h

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/*
 * HashStream.h
 *
 * Copyright (C) 2011 IBR, TU Braunschweig
 *
 * Written-by: Johannes Morgenroth <morgenroth@ibr.cs.tu-bs.de>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#ifndef HASHSTREAM_H_
#define HASHSTREAM_H_

#include "ibrcommon/Exceptions.h"
#include <streambuf>
#include <iostream>
#include <vector>

namespace ibrcommon
{
        class HashStream : public std::basic_streambuf<char, std::char_traits<char> >, public std::iostream
        {
        public:
                HashStream(const unsigned int hash, const size_t buffer = 2048);
                virtual ~HashStream();

                static std::string extract(std::istream &stream);

        protected:
                virtual void update(char *buf, const size_t size) = 0;
                virtual void finalize(char * hash, unsigned int &size) = 0;

                virtual int sync();
                virtual std::char_traits<char>::int_type overflow(std::char_traits<char>::int_type = std::char_traits<char>::eof());
                virtual std::char_traits<char>::int_type underflow();

        private:
                // Output buffer
                std::vector<char> data_buf_;

                // length of the data buffer
                size_t data_size_;

                // Input buffer (contains the hash after finalize)
                std::vector<char> hash_buf_;

                // length of the hash
                unsigned int hash_size_;

                bool final_;
        };
}

#endif /* HASHSTREAM_H_ */