text: //------------------------------------------------------------------------------
  /*
      This file is part of rippled: https://github.com/ripple/rippled
      Copyright (c) 2012, 2013 Ripple Labs Inc.
  
      Permission to use, copy, modify, and/or distribute this software for any
      purpose  with  or without fee is hereby granted, provided that the above
      copyright notice and this permission notice appear in all copies.
  
      THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
      MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
      ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
      WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
      ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
      OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
  //==============================================================================
  
  #ifndef RIPPLE_BASICS_BUFFER_H_INCLUDED
  #define RIPPLE_BASICS_BUFFER_H_INCLUDED
  
  #include <ripple/basics/Slice.h>
  #include <cassert>
  #include <cstdint>
  #include <cstring>
  #include <memory>
  #include <utility>
  
  namespace ripple {
  
  /** Like std::vector<char> but better.
      Meets the requirements of BufferFactory.
  */
  class Buffer
  {
  private:
      std::unique_ptr<std::uint8_t[]> p_;
      std::size_t size_ = 0;
  
  public:
      using const_iterator = std::uint8_t const*;
  
      Buffer() = default;
  
      /** Create an uninitialized buffer with the given size. */
      explicit
      Buffer (std::size_t size)
          : p_ (size ? new std::uint8_t[size] : nullptr)
          , size_ (size)
      {
      }
  
      /** Create a buffer as a copy of existing memory.
  
          @param data a pointer to the existing memory. If
                      size is non-zero, it must not be null.
          @param size size of the existing memory block.
      */
      Buffer (void const* data, std::size_t size)
          : Buffer (size)
      {
          if (size)
              std::memcpy(p_.get(), data, size);
      }
  
      /** Copy-construct */
      Buffer (Buffer const& other)
          : Buffer (other.p_.get(), other.size_)
      {
      }
  
      /** Copy assign */
      Buffer& operator= (Buffer const& other)
      {
          if (this != &other)
          {
              if (auto p = alloc (other.size_))
                  std::memcpy (p, other.p_.get(), size_);
          }
          return *this;
      }
  
      /** Move-construct.
          The other buffer is reset.
      */
      Buffer (Buffer&& other) noexcept
          : p_ (std::move(other.p_))
          , size_ (other.size_)
      {
          other.size_ = 0;
      }
  
      /** Move-assign.
          The other buffer is reset.
      */
      Buffer& operator= (Buffer&& other) noexcept
      {
          if (this != &other)
          {
              p_ = std::move(other.p_);
              size_ = other.size_;
              other.size_ = 0;
          }
          return *this;
      }
  
      /** Construct from a slice */
      explicit
      Buffer (Slice s)
          : Buffer (s.data(), s.size())
      {
      }
  
      /** Assign from slice */
      Buffer& operator= (Slice s)
      {
          // Ensure the slice isn't a subset of the buffer.
          assert (s.size() == 0 || size_ == 0 ||
              s.data() < p_.get() ||
              s.data() >= p_.get() + size_);
  
          if (auto p = alloc (s.size()))
              std::memcpy (p, s.data(), s.size());
          return *this;
      }
  
      /** Returns the number of bytes in the buffer. */
      std::size_t
      size() const noexcept
      {
          return size_;
      }
  
      bool
      empty () const noexcept
      {
          return 0 == size_;
      }
  
      operator Slice() const noexcept
      {
          if (! size_)
              return Slice{};
          return Slice{ p_.get(), size_ };
      }
  
      /** Return a pointer to beginning of the storage.
          @note The return type is guaranteed to be a pointer
                to a single byte, to facilitate pointer arithmetic.
      */
      /** @{ */
      std::uint8_t const*
      data() const noexcept
      {
          return p_.get();
      }
  
      std::uint8_t*
      data() noexcept
      {
          return p_.get();
      }
      /** @} */
  
      /** Reset the buffer.
          All memory is deallocated. The resulting size is 0.
      */
      void
      clear() noexcept
      {
          p_.reset();
          size_ = 0;
      }
  
      /** Reallocate the storage.
          Existing data, if any, is discarded.
      */
      std::uint8_t*
      alloc (std::size_t n)
      {
          if (n != size_)
          {
              p_.reset(n ? new std::uint8_t[n] : nullptr);
              size_ = n;
          }
          return p_.get();
      }
  
      // Meet the requirements of BufferFactory
      void*
      operator()(std::size_t n)
      {
          return alloc(n);
      }
  
      const_iterator
      begin() const noexcept
      {
          return p_.get();
      }
  
      const_iterator
      cbegin() const noexcept
      {
          return p_.get();
      }
  
      const_iterator
      end() const noexcept
      {
          return p_.get() + size_;
      }
  
      const_iterator
      cend() const noexcept
      {
          return p_.get() + size_;
      }
  };
  
  inline bool operator==(Buffer const& lhs, Buffer const& rhs) noexcept
  {
      if (lhs.size() != rhs.size())
          return false;
  
      if (lhs.size() == 0)
          return true;
  
      return std::memcmp(lhs.data(), rhs.data(), lhs.size()) == 0;
  }
  
  inline bool operator!=(Buffer const& lhs, Buffer const& rhs) noexcept
  {
      return !(lhs == rhs);
  }
  
  } // ripple
  
  #endif
  