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.rel;
  
  import com.alibaba.graphscope.common.ir.rel.type.order.GraphFieldCollation;
  import com.google.common.collect.ImmutableList;
  
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelCollation;
  import org.apache.calcite.rel.RelFieldCollation;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.RelShuttle;
  import org.apache.calcite.rel.core.Sort;
  import org.apache.calcite.rel.hint.RelHint;
  import org.apache.calcite.rex.RexNode;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  import java.util.stream.Collectors;
  
  public class GraphLogicalSort extends Sort {
      protected GraphLogicalSort(
              RelOptCluster cluster,
              RelTraitSet traits,
              List<RelHint> hints,
              RelNode child,
              RelCollation collation,
              @Nullable RexNode offset,
              @Nullable RexNode fetch) {
          super(cluster, traits, hints, child, collation, offset, fetch);
      }
  
      public static GraphLogicalSort create(
              RelNode input,
              RelCollation collation,
              @Nullable RexNode offset,
              @Nullable RexNode fetch) {
          return new GraphLogicalSort(
                  input.getCluster(),
                  RelTraitSet.createEmpty(),
                  ImmutableList.of(),
                  input,
                  collation,
                  offset,
                  fetch);
      }
  
      @Override
      public List<RexNode> getSortExps() {
          RelCollation collation = getCollation();
          List<RelFieldCollation> fieldCollations = collation.getFieldCollations();
          return fieldCollations.stream()
                  .map(k -> ((GraphFieldCollation) k).getVariable())
                  .collect(Collectors.toList());
      }
  
      @Override
      public Sort copy(
              RelTraitSet traitSet,
              RelNode newInput,
              RelCollation newCollation,
              @Nullable RexNode offset,
              @Nullable RexNode fetch) {
          return new GraphLogicalSort(
                  getCluster(), traitSet, getHints(), newInput, newCollation, offset, fetch);
      }
  
      @Override
      public RelNode accept(RelShuttle shuttle) {
          if (shuttle instanceof GraphShuttle) {
              return ((GraphShuttle) shuttle).visit(this);
          }
          return shuttle.visit(this);
      }
  }
  