objectstream.hh

// This implementation has been taken from Dune-ALUGrid!
// (dune/alugrid/impl/serial/serialize.h)
// Credit: Bernhard Schupp, 1997-1998 and Robert Kloefkorn 2006
 
#ifndef DUNE_MMESH_MISC_OBJECTSTREAM_HH
#define DUNE_MMESH_MISC_OBJECTSTREAM_HH
 
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <string>
#include <utility>
 
namespace Dune {
 
namespace MMeshImpl {
 
// ObjectStream
// ------------
 
struct ObjectStreamTraits {
  template <class T>
  static void copy(T* dest, const void* src, std::size_t n) {
    for (std::size_t i = 0; i < n; ++i) dest[i] = static_cast<const T*>(src)[i];
  }
 
  template <class T>
  static void copy(void* dest, const T* src, std::size_t n) {
    for (std::size_t i = 0; i < n; ++i) static_cast<T*>(dest)[i] = src[i];
  }
};
 
class ObjectStream {
  using Traits = ObjectStreamTraits;
 
 public:
  char* _buf;
  size_t _rb, _wb, _len;
 
 protected:
  const size_t _bufChunk;
  mutable bool _owner;
 
 public:
  class EOFException {
   public:
    virtual std::string what() const { return "EOFException"; }
  };
 
  class OutOfMemoryException {};
 
  inline ObjectStream(size_t chunk = 0)
      : _buf(0), _rb(0), _wb(0), _len(0), _bufChunk(chunk), _owner(true) {}
 
  inline ObjectStream(const ObjectStream& os)
      : _buf(0),
        _rb(0),
        _wb(0),
        _len(0),
        _bufChunk(os._bufChunk),
        _owner(true) {
    assign(os);
  }
 
  // reset write and read postitions
  inline void clear() {
    _wb = 0;
    _rb = 0;
  }
 
  // reset read position
  inline void resetReadPosition() { _rb = 0; }
 
  void seekp(const size_t pos) {
    _wb = pos;
    assert(_wb <= _len);
  }
 
  // return's true if size > 0 and read position is zero
  // i.e. a read othe stream will result some valid data
  inline bool validToRead() const { return (_wb > 0) && (_rb == 0); }
 
  // return size of bytes allready written to stream
  inline int capacity() const { return _len; }
 
  // return size of bytes allready written to stream
  inline int size() const { return _wb; }
 
  // make sure that s bytes memory can be wrote without reallocation
  inline void reserve(size_t s) {
    const size_t newSize = _wb + s;
    if (newSize > _len) reallocateBuffer(newSize);
  }
 
  // delete stream
  inline ~ObjectStream() { removeObj(); }
 
  // inline const ObjectStream & operator = (const ObjectStream & os)
  inline ObjectStream& operator=(const ObjectStream& os) {
    removeObj();
    assign(os);
    return *this;
  }
 
  // write value to stream
  template <class T>
  inline void write(const T& a) {
    writeT(a, true);
  }
 
  template <class T>
  inline void writeUnchecked(const T& a) {
    writeT(a, false);
  }
 
  // to behave like stringstream
 
  // put char
  inline void put(const signed char a) { write(a); }
 
  // put char with checking buffer size (reserve size before usage)
  inline void putNoChk(const signed char a) { writeUnchecked(a); }
 
  // get char
  inline signed char get() {
    signed char a;
    read(a);
    return a;
  }
 
  // eof function
  bool eof() const { return (this->_rb >= this->_wb); }
 
  // good function
  bool good() const { return (this->_rb < this->_wb); }
 
 
 protected:
  template <class T>
  inline void writeT(const T& a, const bool checkLength) {
    assert(_owner);
    const size_t ap = _wb;
    _wb += sizeof(T);
 
    // if buffer is to small, reallocate
    if (checkLength && _wb > _len) {
      reallocateBuffer(_wb);
    }
    assert(_wb <= _len);
 
    // call assignment operator of type T
    Traits::copy(static_cast<void*>(getBuff(ap)), &a, 1);
    return;
  }
 
  template <class T>
  inline void readT(T& a, bool checkLength) {
    const size_t ap = _rb;
    _rb += sizeof(T);
    assert(_rb <= _wb);
 
    // call assignment operator of type T
    Traits::copy(&a, static_cast<const void*>(getBuff(ap)), 1);
    return;
  }
 
 public:
  // read value from stream
  template <class T>
  inline void read(T& a) {
    readT(a, true);
  }
 
  template <class T>
  inline void readUnchecked(T& a) {
    readT(a, false);
  }
 
  // read this stream and write to os
  inline void readStream(ObjectStream& os) { readStream(os, _wb); }
 
  // read length bytes from this stream and stores it to os
  inline void readStream(ObjectStream& os, const size_t length) {
    if (length == 0) return;
    // actual read position
    os.write(getBuff(_rb), length);
    removeObject(length);
  }
 
  // writes hole stream of os to this stream
  inline void writeStream(const ObjectStream& os) { write(os._buf, os._wb); }
 
  // increments the read position without actualy read data
  inline void removeObject(const size_t length) {
    _rb += length;
    assert(_rb <= _wb);
  }
 
  inline void reset() { removeObj(); }
 
  // static free for use with all buffers here
  inline static void freeBuffer(char* buffer) {
    // free buffer if not zero
    if (buffer) free(buffer);
  }
 
  // compatibility with ostream
  inline void write(const char* buff, const size_t length) {
    assert(_owner);
    if (length == 0) return;
 
    const size_t newWb = _wb + length;
    if (newWb > _len) reallocateBuffer(newWb);
 
    memcpy(getBuff(_wb), buff, length);
    _wb = newWb;
  }
 
  // compatibility with istream
  inline void read(char* buff, const size_t length) {
    if (length == 0) return;
 
    const size_t newRb = _rb + length;
    assert(newRb <= _wb);
 
    memcpy(buff, getBuff(_rb), length);
    _rb = newRb;
  }
 
  // return pointer to buffer memory
  inline char* raw() { return getBuff(0); }
  inline const char* raw() const { return getBuff(0); }
 
  inline char* getBuff(const size_t ap) { return (_buf + ap); }
  inline const char* getBuff(const size_t ap) const { return (_buf + ap); }
 
 protected:
  // reallocated the buffer if necessary
  inline void reallocateBuffer(size_t newSize) {
    assert(_owner);
    _len += _bufChunk;
    if (_len < newSize) _len = newSize;
    _buf = (char*)realloc(_buf, _len);
    if (!_buf) {
      perror("**EXCEPTION in ObjectStream :: reallocateBuffer(size_t) ");
      throw OutOfMemoryException();
    }
  }
 
  // delete buffer
  inline void removeObj() {
    if (_owner) freeBuffer(_buf);
    _buf = 0;
    _len = 0;
    _wb = 0;
    _rb = 0;
    _owner = true;
    return;
  }
 
  // assign buffer
  inline void assign(const ObjectStream& os) {
    assert(_buf == 0);
    if (os._len > 0) {
      _len = os._len;
      _wb = os._wb;
      _rb = os._rb;
      const_cast<size_t&>(_bufChunk) = os._bufChunk;
 
      // overtake buffer and set ownership of os to false
      _buf = os._buf;
      os._owner = false;
      // we are owner now
      _owner = true;
    }
    return;
  }
 
  inline void assign(char* buff, const size_t length) {
    if (length == 0) return;
 
    // if length > 0, buff should be valid
    assert(buff);
 
    // set length
    _wb = _len = length;
    // set buffer
    _buf = buff;
 
    // read status is zero
    _rb = 0;
 
    // we are the owner
    _owner = true;
    return;
  }
};
 
}  // namespace MMeshImpl
 
}  // namespace Dune
 
#endif  // #ifndef DUNE_MMESH_MISC_OBJECTSTREAM_HH