IO/XML/vtkXMLOffsetsManager.h

/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkXMLOffsetsManager.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
/**
 * @class   OffsetsManager
 * @brief   Helper class due to PIMPL excess
 *
 * This class is deisgned to work within vtkXMLWriter. It store a position
 * in a file (unsigned long) and associate a offset in the file. This is
 * useful when writing TimeStep XML file when you want to forward the
 * same offset from the AppendData section on every entry in let say
 * \<Points\> definition
 * Example:
 * \verbatim
 * <Points>
 *   <DataArray type="Float32" TimeStep="0" format="appended" offset="268" />
 *   <DataArray type="Float32" TimeStep="1" format="appended" offset="268" />
 *   ...
 * </Points>
 * \endverbatim
 * Therefore data is only stored once in the XML file. At read time the
 * offset value is stored to determine whenever we need to read data
 * (ie when offset different from previously stored offset)
 *
 * @sa
 * vtkXMLWriter
 * @warning
 * Do not include this file in a header file, it will break PIMPL convention
*/

#ifndef vtkXMLOffsetsManager_DoNotInclude
#error "do not include unless you know what you are doing"
#endif

#ifndef vtkXMLOffsetsManager_h
#define vtkXMLOffsetsManager_h

#include "vtkSystemIncludes.h"
#include <vector>
#include <cassert>

//----------------------------------------------------------------------------
class OffsetsManager
{
public:
  // Construct with default (vtkMTimeType)-1  MTime
  OffsetsManager()
  {
      this->LastMTime = static_cast<vtkMTimeType>(-1); //almost invalid state
  }
  void Allocate(int numTimeStep)
  {
    assert( numTimeStep > 0);
    this->Positions.resize(numTimeStep);
    this->RangeMinPositions.resize(numTimeStep);
    this->RangeMaxPositions.resize(numTimeStep);
    this->OffsetValues.resize(numTimeStep);
  }
  vtkTypeInt64 &GetPosition(unsigned int t)
  {
    assert( t < this->Positions.size());
    return this->Positions[t];
  }
  vtkTypeInt64 &GetRangeMinPosition(unsigned int t)
  {
    assert( t < this->RangeMinPositions.size());
    return this->RangeMinPositions[t];
  }
  vtkTypeInt64 &GetRangeMaxPosition(unsigned int t)
  {
    assert( t < this->RangeMaxPositions.size());
    return this->RangeMaxPositions[t];
  }
  vtkTypeInt64 &GetOffsetValue(unsigned int t)
  {
    assert( t < this->OffsetValues.size());
    return this->OffsetValues[t];
  }
  vtkMTimeType &GetLastMTime()
  {
    return this->LastMTime;
  }
private:
  vtkMTimeType LastMTime; // Previously written dataarray mtime
  // at some point these vectors could become a vector of map <string,ul>
  // where the string is the name of the offset, but that would be pretty fat
  // and slow, but if another couple offsets are added then we should
  // consider doing it
  // Position in the stream to write the offset
  std::vector<vtkTypeInt64> Positions;
  std::vector<vtkTypeInt64> RangeMinPositions; // Where is this
  std::vector<vtkTypeInt64> RangeMaxPositions; // Whee is this

  std::vector<vtkTypeInt64> OffsetValues;    // Value of offset
};

//----------------------------------------------------------------------------
class OffsetsManagerGroup
{
public:
  // This is kind of a hack since we need to consider both the case of Points
  // with only one array over time and PointData with possibly multiple array
  // over time therefore we need to use a OffsetsManagerGroup for
  // representing offset from Points but OffsetsManagerArray for
  // PointData. In both case the toplevel structure is a container of
  // Pieces...
  OffsetsManager &GetPiece(unsigned int index)
  {
    assert( index < this->Internals.size());
    OffsetsManager &e = this->Internals[index];
    return e;
  }
  // GetElement should be used when manipulating a OffsetsManagerArray
  OffsetsManager &GetElement(unsigned int index)
  {
    // commenting the following out, this is an heisenbug which only appears
    // on gcc when exporting GLIBCPP_NEW=1. If you try to print the value or
    // run through gdb it desepears //assert( index <
    // this->Internals.size());
    OffsetsManager &e = this->Internals[index];
    return e;
  }
  unsigned int GetNumberOfElements()
  {
    return static_cast<unsigned int>(this->Internals.size());
  }
  void Allocate(int numElements)
  {
    assert(numElements >= 0); //allow 0 for empty FieldData
    this->Internals.resize(numElements);
  }
  void Allocate(int numElements, int numTimeSteps)
  {
    assert(numElements > 0);
    assert(numTimeSteps > 0);
    this->Internals.resize(numElements);
    for(int i=0; i<numElements; i++)
    {
      this->Internals[i].Allocate(numTimeSteps);
    }
  }
private:
  std::vector<OffsetsManager> Internals;
};

//----------------------------------------------------------------------------
class OffsetsManagerArray
{
public:
  OffsetsManagerGroup &GetPiece(unsigned int index)
  {
    assert( index < this->Internals.size());
    return this->Internals[index];
  }
  void Allocate(int numPieces)
  {
    assert(numPieces > 0);
    // Force re-initialization of values.
    this->Internals.resize(0);
    this->Internals.resize(numPieces);
  }
  void Allocate(int numPieces, int numElements, int numTimeSteps)
  {
    assert(numPieces > 0);
    assert(numElements > 0);
    assert(numTimeSteps > 0);

    // Force re-initialization of values.
    this->Internals.resize(0);
    this->Internals.resize(numPieces);
    for(int i=0; i<numPieces; i++)
    {
      this->Internals[i].Allocate(numElements, numTimeSteps);
    }
  }
private:
  std::vector<OffsetsManagerGroup> Internals;
};

#endif
// VTK-HeaderTest-Exclude: vtkXMLOffsetsManager.h