core/sql/executor/MdamRefListIterator.cpp

/* -*-C++-*-
********************************************************************************
*
* File:         MdamRefListIterator.C
* Description:  Implimentation for MDAM Reference List Iterator
*               
*               
* Created:      9/12/96
* Language:     C++
*
*
// @@@ START COPYRIGHT @@@
//
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
//
// @@@ END COPYRIGHT @@@
*
*
********************************************************************************
*/

// -----------------------------------------------------------------------------

#include "ex_stdh.h"
#include "NABoolean.h"
#include "MdamRefListIterator.h"

// *****************************************************************************
// Member functions for class MdamRefListIterator
// *****************************************************************************
  

// Constructor.
MdamRefListIterator::MdamRefListIterator(const MdamRefList * RefListPtr)
        : currentListPtr_ (RefListPtr), currentEntryPtr_ (0)
{
  // Set currentEntryPtr_ to point to the first node.
  if (currentListPtr_->lastEntryPtr_ != 0)  // Non-empty list?
    {
      currentEntryPtr_ = currentListPtr_->lastEntryPtr_->getNextEntryPtr();
    }
}


// Iteration operator returns a boolean that indicates if there was or
// was not a "next" entry and the corresponding disjunct number.
// When the function returns, currentEntryPtr_ points to the next
// unprocessed entry, if any.  
NABoolean MdamRefListIterator::operator() (Int32 & disjunctNum)
{
  if (currentEntryPtr_ == 0)
    {
      return FALSE;
    }
  disjunctNum = currentEntryPtr_->getDisjunctNum();
  if (currentEntryPtr_ == currentListPtr_->lastEntryPtr_)
    {
      currentEntryPtr_ = 0;
    }
  else
    {   
      currentEntryPtr_ = currentEntryPtr_->getNextEntryPtr();
    }
  return TRUE;
}


// Iteration operator returns a pointer to the next entry. 
// When the function returns, currentEntryPtr_ points to the
// reference list entry beyond the one returned.
// So, it is safe for a user of this iterator to delete the returned object.
MdamRefListEntry * MdamRefListIterator::operator()()
{
  MdamRefListEntry * tempEntryPtr = currentEntryPtr_;
  if (currentEntryPtr_ != 0)
    {
        if (currentEntryPtr_ == currentListPtr_->lastEntryPtr_)
        {
          currentEntryPtr_ = 0;
        }
      else
        {   
          currentEntryPtr_ = currentEntryPtr_->getNextEntryPtr();
        }
    }
  return tempEntryPtr;
}