padding_ostream.hpp

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/*
 * Copyright (c) 2015 Cryptonomex, Inc., and contributors.
 *
 * The MIT License
 *
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 * of this software and associated documentation files (the "Software"), to deal
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 * furnished to do so, subject to the following conditions:
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 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
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#pragma once

namespace graphene { namespace utilities {

template<size_t BlockSize=16, char PaddingChar=' '>
class padding_ostream : public fc::buffered_ostream {
public:
   padding_ostream( fc::ostream_ptr o, size_t bufsize = 4096 ) : buffered_ostream(o, bufsize) {}
   virtual ~padding_ostream() {}

   virtual size_t writesome( const char* buffer, size_t len ) {
      auto out = buffered_ostream::writesome(buffer, len);
      bytes_out += out;
      bytes_out %= BlockSize;
      return out;
   }
   virtual size_t writesome( const std::shared_ptr<const char>& buf, size_t len, size_t offset ) {
      auto out = buffered_ostream::writesome(buf, len, offset);
      bytes_out += out;
      bytes_out %= BlockSize;
      return out;
   }
   virtual void flush() {
      static const char pad = PaddingChar;
      while( bytes_out % BlockSize )
         writesome(&pad, 1);
      buffered_ostream::flush();
   }

private:
   size_t bytes_out = 0;
};

} } //graphene::utilities