DynamicBuffer.h

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/*
 * Copyright (C) 2007-2015 Hypertable, Inc.
 *
 * This file is part of Hypertable.
 *
 * Hypertable is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 3
 * of the License, or any later version.
 *
 * Hypertable is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#ifndef Common_DynamicBuffer_h
#define Common_DynamicBuffer_h

#include <cstdint>
#include <cstring>
#include <memory>

namespace Hypertable {

  class DynamicBuffer {

  public:
    explicit DynamicBuffer(size_t initial_size = 0, bool own_buffer = true)
        : size(initial_size), own(own_buffer) {
      if (size)
        base = ptr = mark = new uint8_t[size];
      else
        base = ptr = mark = 0;
    }

    ~DynamicBuffer() {
      if (own)
        delete [] base;
    }

    size_t remaining() const { return size - (ptr - base); }

    size_t fill() const { return ptr - base; }

    bool empty() const { return ptr == base; }

    void ensure(size_t len) {
      if (len > remaining())
        grow((fill() + len) * 3 / 2);
    }

    void reserve(size_t len, bool nocopy = false) {
      if (len > remaining())
        grow(fill() + len, nocopy);
    }

    uint8_t *add_unchecked(const void *data, size_t len) {
      if (data == 0)
        return 0;
      uint8_t *rptr = ptr;
      memcpy(ptr, data, len);
      ptr += len;
      return rptr;
    }

    uint8_t *add(const void *data, size_t len) {
      ensure(len);
      return add_unchecked(data, len);
    }

    void set(const void *data, size_t len) {
      clear();
      reserve(len);
      add_unchecked(data, len);
    }

    void clear() {
      ptr = base;
    }

    void set_mark() {
      mark = ptr;
    }

    void free() {
      if (own)
        delete [] base;
      base = ptr = mark = 0;
      size = 0;
    }

    uint8_t *release(size_t *lenp = 0) {
      uint8_t *rbuf = base;
      if (lenp)
        *lenp = fill();
      ptr = base = mark = 0;
      size = 0;
      return rbuf;
    }

    void grow(size_t new_size, bool nocopy = false) {
      uint8_t *new_buf = new uint8_t[new_size];

      if (!nocopy && base)
        memcpy(new_buf, base, ptr-base);

      ptr = new_buf + (ptr-base);
      mark = new_buf + (mark-base);
      if (own)
        delete [] base;
      base = new_buf;
      size = new_size;
    }

    uint8_t *base;

    uint8_t *ptr;

    uint8_t *mark;

    uint32_t size;

    bool own;
  };

  typedef std::shared_ptr<DynamicBuffer> DynamicBufferPtr;

}



#endif // Common_DynamicBuffer_h