/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * 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.

 */

package com.sun.org.apache.xpath.internal.axes;

import com.sun.org.apache.xml.internal.dtm.DTM;

import com.sun.org.apache.xml.internal.dtm.DTMFilter;

import com.sun.org.apache.xml.internal.dtm.DTMIterator;

import com.sun.org.apache.xml.internal.utils.PrefixResolver;

import com.sun.org.apache.xpath.internal.compiler.Compiler;

import com.sun.org.apache.xpath.internal.compiler.OpMap;

/**

 * Base for iterators that handle predicates.  Does the basic next

 * node logic, so all the derived iterator has to do is get the

 * next node.

 */

public abstract class BasicTestIterator extends LocPathIterator

{

    static final long serialVersionUID = 3505378079378096623L;

  /**

   * Create a LocPathIterator object.

   *

   * @param nscontext The namespace context for this iterator,

   * should be OK if null.

   */

  protected BasicTestIterator()

  {

  }

  /**

   * Create a LocPathIterator object.

   *

   * @param nscontext The namespace context for this iterator,

   * should be OK if null.

   */

  protected BasicTestIterator(PrefixResolver nscontext)

  {

    super(nscontext);

  }

  /**

   * Create a LocPathIterator object, including creation

   * of step walkers from the opcode list, and call back

   * into the Compiler to create predicate expressions.

   *

   * @param compiler The Compiler which is creating

   * this expression.

   * @param opPos The position of this iterator in the

   * opcode list from the compiler.

   *

   * @throws javax.xml.transform.TransformerException

   */

  protected BasicTestIterator(Compiler compiler, int opPos, int analysis)

          throws javax.xml.transform.TransformerException

  {

    super(compiler, opPos, analysis, false);

    int firstStepPos = OpMap.getFirstChildPos(opPos);

    int whatToShow = compiler.getWhatToShow(firstStepPos);

    if ((0 == (whatToShow

               & (DTMFilter.SHOW_ATTRIBUTE

               | DTMFilter.SHOW_NAMESPACE

               | DTMFilter.SHOW_ELEMENT

               | DTMFilter.SHOW_PROCESSING_INSTRUCTION)))

               || (whatToShow == DTMFilter.SHOW_ALL))

      initNodeTest(whatToShow);

    else

    {

      initNodeTest(whatToShow, compiler.getStepNS(firstStepPos),

                              compiler.getStepLocalName(firstStepPos));

    }

    initPredicateInfo(compiler, firstStepPos);

  }

  /**

   * Create a LocPathIterator object, including creation

   * of step walkers from the opcode list, and call back

   * into the Compiler to create predicate expressions.

   *

   * @param compiler The Compiler which is creating

   * this expression.

   * @param opPos The position of this iterator in the

   * opcode list from the compiler.

   * @param shouldLoadWalkers True if walkers should be

   * loaded, or false if this is a derived iterator and

   * it doesn't wish to load child walkers.

   *

   * @throws javax.xml.transform.TransformerException

   */

  protected BasicTestIterator(

          Compiler compiler, int opPos, int analysis, boolean shouldLoadWalkers)

            throws javax.xml.transform.TransformerException

  {

    super(compiler, opPos, analysis, shouldLoadWalkers);

  }

  /**

   * Get the next node via getNextXXX.  Bottlenecked for derived class override.

   * @return The next node on the axis, or DTM.NULL.

   */

  protected abstract int getNextNode();

  /**

   *  Returns the next node in the set and advances the position of the

   * iterator in the set. After a NodeIterator is created, the first call

   * to nextNode() returns the first node in the set.

   *

   * @return  The next <code>Node</code> in the set being iterated over, or

   *   <code>null</code> if there are no more members in that set.

   */

  public int nextNode()

  {

        if(m_foundLast)

        {

                m_lastFetched = DTM.NULL;

                return DTM.NULL;

        }

    if(DTM.NULL == m_lastFetched)

    {

      resetProximityPositions();

    }

    int next;

    com.sun.org.apache.xpath.internal.VariableStack vars;

    int savedStart;

    if (-1 != m_stackFrame)

    {

      vars = m_execContext.getVarStack();

      // These three statements need to be combined into one operation.

      savedStart = vars.getStackFrame();

      vars.setStackFrame(m_stackFrame);

    }

    else

    {

      // Yuck.  Just to shut up the compiler!

      vars = null;

      savedStart = 0;

    }

    try

    {

      do

      {

        next = getNextNode();

        if (DTM.NULL != next)

        {

          if(DTMIterator.FILTER_ACCEPT == acceptNode(next))

            break;

          else

            continue;

        }

        else

          break;

      }

      while (next != DTM.NULL);

      if (DTM.NULL != next)

      {

        m_pos++;

        return next;

      }

      else

      {

        m_foundLast = true;

        return DTM.NULL;

      }

    }

    finally

    {

      if (-1 != m_stackFrame)

      {

        // These two statements need to be combined into one operation.

        vars.setStackFrame(savedStart);

      }

    }

  }

  /**

   *  Get a cloned Iterator that is reset to the beginning

   *  of the query.

   *

   *  @return A cloned NodeIterator set of the start of the query.

   *

   *  @throws CloneNotSupportedException

   */

  public DTMIterator cloneWithReset() throws CloneNotSupportedException

  {

    ChildTestIterator clone = (ChildTestIterator) super.cloneWithReset();

    clone.resetProximityPositions();

    return clone;

  }

}