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.function.Experimental;
  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.RelOptTable;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelCollationTraitDef;
  import org.apache.calcite.rel.RelDistributionTraitDef;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.Spool;
  import org.apache.calcite.rel.core.TableSpool;
  import org.apache.calcite.rel.metadata.RelMetadataQuery;
  import org.apache.calcite.schema.ModifiableTable;
  import org.apache.calcite.util.BuiltInMethod;
  
  /**
   * Implementation of {@link TableSpool} in
   * {@link EnumerableConvention enumerable calling convention}
   * that writes into a {@link ModifiableTable} (which must exist in the current
   * schema).
   *
   * <p>NOTE: The current API is experimental and subject to change without
   * notice.
   */
  @Experimental
  public class EnumerableTableSpool extends TableSpool implements EnumerableRel {
  
    private EnumerableTableSpool(RelOptCluster cluster, RelTraitSet traitSet,
        RelNode input, Type readType, Type writeType, RelOptTable table) {
      super(cluster, traitSet, input, readType, writeType, table);
    }
  
    /** Creates an EnumerableTableSpool. */
    public static EnumerableTableSpool create(RelNode input, Type readType,
        Type writeType, RelOptTable table) {
      RelOptCluster cluster = input.getCluster();
      RelMetadataQuery mq = cluster.getMetadataQuery();
      RelTraitSet traitSet = cluster.traitSetOf(EnumerableConvention.INSTANCE)
          .replaceIfs(RelCollationTraitDef.INSTANCE,
              () -> mq.collations(input))
          .replaceIf(RelDistributionTraitDef.INSTANCE,
              () -> mq.distribution(input));
      return new EnumerableTableSpool(cluster, traitSet, input, readType, writeType, table);
    }
  
    @Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
      // TODO for the moment only LAZY read & write is supported
      if (readType != Type.LAZY || writeType != Type.LAZY) {
        throw new UnsupportedOperationException(
            "EnumerableTableSpool supports for the moment only LAZY read and LAZY write");
      }
  
      //  ModifiableTable t = (ModifiableTable) root.getRootSchema().getTable(tableName);
      //  return lazyCollectionSpool(t.getModifiableCollection(), <inputExp>);
  
      BlockBuilder builder = new BlockBuilder();
  
      RelNode input = getInput();
      Result inputResult = implementor.visitChild(this, 0, (EnumerableRel) input, pref);
  
      String tableName = table.getQualifiedName().get(table.getQualifiedName().size() - 1);
      Expression tableExp =
          Expressions.convert_(
              Expressions.call(
                  Expressions.call(implementor.getRootExpression(),
                      BuiltInMethod.DATA_CONTEXT_GET_ROOT_SCHEMA.method),
                  BuiltInMethod.SCHEMA_GET_TABLE.method,
                  Expressions.constant(tableName, String.class)),
              ModifiableTable.class);
      Expression collectionExp =
          Expressions.call(tableExp,
              BuiltInMethod.MODIFIABLE_TABLE_GET_MODIFIABLE_COLLECTION.method);
  
      Expression inputExp = builder.append("input", inputResult.block);
  
      Expression spoolExp =
          Expressions.call(BuiltInMethod.LAZY_COLLECTION_SPOOL.method,
              collectionExp, inputExp);
      builder.add(spoolExp);
  
      PhysType physType =
          PhysTypeImpl.of(implementor.getTypeFactory(),
              getRowType(), pref.prefer(inputResult.format));
      return implementor.result(physType, builder.toBlock());
    }
  
    @Override protected Spool copy(RelTraitSet traitSet, RelNode input,
        Type readType, Type writeType) {
      return new EnumerableTableSpool(input.getCluster(), traitSet, input,
          readType, writeType, table);
    }
  }
  