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.interpreter;
  
  import org.apache.calcite.linq4j.Enumerable;
  import org.apache.calcite.linq4j.Enumerator;
  import org.apache.calcite.linq4j.function.Function1;
  import org.apache.calcite.rel.core.TableFunctionScan;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rex.RexCall;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.schema.Function;
  import org.apache.calcite.schema.impl.TableFunctionImpl;
  import org.apache.calcite.sql.SqlOperator;
  import org.apache.calcite.sql.validate.SqlUserDefinedTableFunction;
  
  import com.google.common.collect.ImmutableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * Interpreter node that implements a
   * {@link TableFunctionScan}.
   */
  public class TableFunctionScanNode implements Node {
    private final Scalar scalar;
    private final Context context;
    private final Sink sink;
    private final Function1<?, Row> mapFn;
  
    private TableFunctionScanNode(Compiler compiler, TableFunctionScan rel) {
      final RelDataType rowType = rel.getRowType();
      this.scalar = compiler.compile(ImmutableList.of(rel.getCall()), rowType);
      this.context = compiler.createContext();
      this.sink = compiler.sink(rel);
      if (rowType.getFieldCount() == 1
          && rel.getElementType() != Object[].class) {
        this.mapFn = (Function1<Object, Row>) Row::of;
      } else {
        this.mapFn = (Function1<@Nullable Object[], Row>) Row::asCopy;
      }
    }
  
    @Override public void run() throws InterruptedException {
      final Object o = scalar.execute(context);
      if (o instanceof Enumerable) {
        for (@SuppressWarnings({"unchecked", "rawtypes"})
             final Enumerator<Row> enumerator =
             ((Enumerable) o).select(mapFn).enumerator();
             enumerator.moveNext();) {
          sink.send(enumerator.current());
        }
      }
    }
  
    /** Creates a TableFunctionScanNode. */
    static TableFunctionScanNode create(Compiler compiler, TableFunctionScan rel) {
      RexNode call = rel.getCall();
      if (call instanceof RexCall) {
        SqlOperator operator = ((RexCall) call).getOperator();
        if (operator instanceof SqlUserDefinedTableFunction) {
          Function function = ((SqlUserDefinedTableFunction) operator).function;
          if (function instanceof TableFunctionImpl) {
            return new TableFunctionScanNode(compiler, rel);
          }
        }
      }
      throw new AssertionError("cannot convert table function scan "
          + rel.getCall() + " to enumerable");
    }
  }
  