content: /*
   *
   *  * Copyright 2020 Alibaba Group Holding Limited.
   *  *
   *  * 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.
   *
   */
  
  package com.alibaba.graphscope.common.ir.type;
  
  import com.google.common.base.Objects;
  import com.google.common.base.Preconditions;
  import com.google.common.collect.ImmutableList;
  
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * Maintain path element types in an interleaved way.
   */
  public class InterleavedVELabelTypes extends GraphLabelType implements Iterator<GraphLabelType> {
      private final List<GraphLabelType> unionTypes;
      private int cursor;
  
      public InterleavedVELabelTypes(GraphLabelType expandLabelType, GraphLabelType getVLabelType) {
          super(expandLabelType.getLabelsEntry());
          Preconditions.checkArgument(
                  !(expandLabelType instanceof InterleavedVELabelTypes)
                          && !(getVLabelType instanceof InterleavedVELabelTypes));
          this.unionTypes = ImmutableList.of(expandLabelType, getVLabelType);
          this.cursor = 0;
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
          if (o == null || getClass() != o.getClass()) return false;
          if (!super.equals(o)) return false;
          InterleavedVELabelTypes that = (InterleavedVELabelTypes) o;
          return Objects.equal(unionTypes, that.unionTypes);
      }
  
      @Override
      public int hashCode() {
          return Objects.hashCode(super.hashCode(), unionTypes);
      }
  
      @Override
      protected void generateTypeString(StringBuilder sb, boolean withDetail) {
          sb.append("UNION_V_E(" + unionTypes + ")");
      }
  
      @Override
      public boolean hasNext() {
          return true;
      }
  
      @Override
      public GraphLabelType next() {
          cursor = 1 - cursor;
          return unionTypes.get(cursor);
      }
  
      public void resetCursor() {
          cursor = 0;
      }
  }
  