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/*
 * Copyright © 2021-present Arcade Data Ltd ([email protected])
 *
 * Licensed 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.
 *
 * SPDX-FileCopyrightText: 2021-present Arcade Data Ltd ([email protected])
 * SPDX-License-Identifier: Apache-2.0
 */
package com.arcadedb.graph;

import com.arcadedb.database.RID;
import com.arcadedb.exception.RecordNotFoundException;

import java.util.*;

public class VertexIterator extends ResettableIteratorBase {

  public VertexIterator(final EdgeSegment current) {
    super(null, current);
  }

  @Override
  public boolean hasNext() {
    if (currentContainer == null)
      return false;

    if (currentPosition.get() < currentContainer.getUsed())
      return true;

    currentContainer = currentContainer.getPrevious();
    if (currentContainer != null) {
      currentPosition.set(MutableEdgeSegment.CONTENT_START_POSITION);
      return currentPosition.get() < currentContainer.getUsed();
    }
    return false;
  }

  @Override
  public Vertex next() {
    while (true) {
      if (!hasNext())
        throw new NoSuchElementException();

      currentContainer.getRID(currentPosition); // SKIP EDGE
      final RID rid = currentContainer.getRID(currentPosition);

      ++browsed;

      try {
        // LAZY LOAD THE CONTENT TO IMPROVE PERFORMANCE WITH TRAVERSAL. NOTE: THE RECORD NOT FOUND WILL NEVER BE TRIGGERED HERE ANYMORE
        return rid.asVertex(false);
      } catch (final RecordNotFoundException e) {
        // SKIP
      }
    }
  }
}