content: /*
   * Copyright 2021 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.ds;
  
  import static com.alibaba.graphscope.utils.CppClassName.PROJECTED_ADJ_LIST;
  import static com.alibaba.graphscope.utils.CppHeaderName.ARROW_PROJECTED_FRAGMENT_H;
  import static com.alibaba.graphscope.utils.CppHeaderName.CORE_JAVA_TYPE_ALIAS_H;
  
  import com.alibaba.fastffi.CXXHead;
  import com.alibaba.fastffi.CXXValue;
  import com.alibaba.fastffi.FFIGen;
  import com.alibaba.fastffi.FFINameAlias;
  import com.alibaba.fastffi.FFIPointer;
  import com.alibaba.fastffi.FFITypeAlias;
  
  import java.util.Iterator;
  
  /**
   * AdjList used by {@link com.alibaba.graphscope.fragment.ArrowProjectedFragment}, java wrapper for
   * <a
   * href="https://github.com/alibaba/GraphScope/blob/main/analytical_engine/core/fragment/arrow_projected_fragment.h#L260">ProjectedAdjList</a>.
   *
   * @param <VID_T> vertex id type.
   * @param <EDATA_T> edge data type.
   */
  @FFIGen
  @CXXHead(ARROW_PROJECTED_FRAGMENT_H)
  @CXXHead(CORE_JAVA_TYPE_ALIAS_H)
  @FFITypeAlias(PROJECTED_ADJ_LIST)
  public interface ProjectedAdjList<VID_T, EDATA_T> extends FFIPointer {
  
      /**
       * Get the first Nbr.
       *
       * @return first Nbr.
       */
      @CXXValue
      ProjectedNbr<VID_T, EDATA_T> begin();
  
      /**
       * Get the last Nbr.
       *
       * @return last Nbr.
       */
      @CXXValue
      ProjectedNbr<VID_T, EDATA_T> end();
  
      /**
       * Size for this AdjList, i.e. number of nbrs.
       *
       * @return size.
       */
      @FFINameAlias("Size")
      long size();
  
      /**
       * Check empty.
       *
       * @return true if no nbr.
       */
      @FFINameAlias("Empty")
      boolean empty();
  
      /**
       * Check no-empty.
       *
       * @return false if empty.
       */
      @FFINameAlias("NotEmpty")
      boolean notEmpty();
  
      /**
       * The iterator for ProjectedAdjList. You can use enhanced for loop instead of directly using
       * this.
       *
       * @return the iterator.
       */
      default Iterable<ProjectedNbr<VID_T, EDATA_T>> iterable() {
          return () ->
                  new Iterator<ProjectedNbr<VID_T, EDATA_T>>() {
                      ProjectedNbr<VID_T, EDATA_T> cur = begin().dec();
                      ProjectedNbr<VID_T, EDATA_T> end = end();
                      boolean flag = false;
  
                      @Override
                      public boolean hasNext() {
                          if (!flag) {
                              cur = cur.inc();
                              flag = !cur.eq(end);
                          }
                          return flag;
                      }
  
                      @Override
                      public ProjectedNbr<VID_T, EDATA_T> next() {
                          flag = false;
                          return cur;
                      }
                  };
      }
  }
  