content: /*
   * 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.calcite.adapter.enumerable;
  
  import org.apache.calcite.linq4j.tree.BlockBuilder;
  import org.apache.calcite.linq4j.tree.Expression;
  import org.apache.calcite.linq4j.tree.Expressions;
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelCollation;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.Sort;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.util.BuiltInMethod;
  import org.apache.calcite.util.Pair;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /** Implementation of {@link org.apache.calcite.rel.core.Sort} in
   * {@link org.apache.calcite.adapter.enumerable.EnumerableConvention enumerable calling convention}. */
  public class EnumerableSort extends Sort implements EnumerableRel {
    /**
     * Creates an EnumerableSort.
     *
     * <p>Use {@link #create} unless you know what you're doing.
     */
    public EnumerableSort(RelOptCluster cluster, RelTraitSet traitSet,
        RelNode input, RelCollation collation, @Nullable RexNode offset, @Nullable RexNode fetch) {
      super(cluster, traitSet, input, collation, offset, fetch);
      assert getConvention() instanceof EnumerableConvention;
      assert getConvention() == input.getConvention();
      assert fetch == null : "fetch must be null";
      assert offset == null : "offset must be null";
    }
  
    /** Creates an EnumerableSort. */
    public static EnumerableSort create(RelNode child, RelCollation collation,
        @Nullable RexNode offset, @Nullable RexNode fetch) {
      final RelOptCluster cluster = child.getCluster();
      final RelTraitSet traitSet =
          cluster.traitSetOf(EnumerableConvention.INSTANCE)
              .replace(collation);
      return new EnumerableSort(cluster, traitSet, child, collation, offset,
          fetch);
    }
  
    @Override public EnumerableSort copy(
        RelTraitSet traitSet,
        RelNode newInput,
        RelCollation newCollation,
        @Nullable RexNode offset,
        @Nullable RexNode fetch) {
      return new EnumerableSort(getCluster(), traitSet, newInput, newCollation,
          offset, fetch);
    }
  
    @Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
      final BlockBuilder builder = new BlockBuilder();
      final EnumerableRel child = (EnumerableRel) getInput();
      final Result result = implementor.visitChild(this, 0, child, pref);
      final PhysType physType =
          PhysTypeImpl.of(
              implementor.getTypeFactory(),
              getRowType(),
              result.format);
      Expression childExp =
          builder.append("child", result.block);
  
      PhysType inputPhysType = result.physType;
      final Pair<Expression, Expression> pair =
          inputPhysType.generateCollationKey(
              collation.getFieldCollations());
  
      builder.add(
          Expressions.return_(null,
              Expressions.call(childExp,
                  BuiltInMethod.ORDER_BY.method,
                  Expressions.list(
                      builder.append("keySelector", pair.left))
                      .appendIfNotNull(
                          builder.appendIfNotNull("comparator", pair.right)))));
      return implementor.result(physType, builder.toBlock());
    }
  }
  