/*
    * 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 org.apache.commons.jxpath.ri.axes;
  
  import org.apache.commons.jxpath.Pointer;
  import org.apache.commons.jxpath.ri.EvalContext;
  import org.apache.commons.jxpath.ri.compiler.NodeTest;
  import org.apache.commons.jxpath.ri.model.NodePointer;
  
  /**
   * EvalContext that returns the current node from the parent context if the test succeeds.
   */
  public class SelfContext extends EvalContext {
  
      private final NodeTest nodeTest;
      private boolean startedSet;
      private NodePointer nodePointer;
  
      /**
       * Constructs a new SelfContext.
       *
       * @param parentContext EvalContext
       * @param nodeTest      guard
       */
      public SelfContext(final EvalContext parentContext, final NodeTest nodeTest) {
          super(parentContext);
          this.nodeTest = nodeTest;
      }
  
      @Override
      public NodePointer getCurrentNodePointer() {
          if (position == 0 && !setPosition(1)) {
              return null;
          }
          return nodePointer;
      }
  
      @Override
      public Pointer getSingleNodePointer() {
          return parentContext.getSingleNodePointer();
      }
  
      @Override
      public boolean nextNode() {
          return setPosition(getCurrentPosition() + 1);
      }
  
      @Override
      public void reset() {
          super.reset();
          startedSet = false;
      }
  
      @Override
      public boolean setPosition(final int position) {
          if (position != 1) {
              return false;
          }
          super.setPosition(position);
          if (!startedSet) {
              startedSet = true;
              nodePointer = parentContext.getCurrentNodePointer();
          }
          if (nodePointer == null) {
              return false;
          }
          return nodeTest == null || nodePointer.testNode(nodeTest);
      }
  }