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.rel.rules;
  
  import org.apache.calcite.adapter.enumerable.EnumerableInterpreter;
  import org.apache.calcite.interpreter.Bindables;
  import org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.calcite.plan.RelOptRuleOperand;
  import org.apache.calcite.plan.RelOptTable;
  import org.apache.calcite.plan.RelRule;
  import org.apache.calcite.rel.core.Filter;
  import org.apache.calcite.rel.core.TableScan;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.rex.RexUtil;
  import org.apache.calcite.schema.FilterableTable;
  import org.apache.calcite.schema.ProjectableFilterableTable;
  import org.apache.calcite.tools.RelBuilderFactory;
  import org.apache.calcite.util.ImmutableIntList;
  import org.apache.calcite.util.mapping.Mapping;
  import org.apache.calcite.util.mapping.Mappings;
  
  import com.google.common.collect.ImmutableList;
  
  import org.immutables.value.Value;
  
  /**
   * Planner rule that converts
   * a {@link org.apache.calcite.rel.core.Filter}
   * on a {@link org.apache.calcite.rel.core.TableScan}
   * of a {@link org.apache.calcite.schema.FilterableTable}
   * or a {@link org.apache.calcite.schema.ProjectableFilterableTable}
   * to a {@link org.apache.calcite.interpreter.Bindables.BindableTableScan}.
   *
   * <p>The {@link CoreRules#FILTER_INTERPRETER_SCAN} variant allows an
   * intervening
   * {@link org.apache.calcite.adapter.enumerable.EnumerableInterpreter}.
   *
   * @see org.apache.calcite.rel.rules.ProjectTableScanRule
   * @see CoreRules#FILTER_SCAN
   * @see CoreRules#FILTER_INTERPRETER_SCAN
   */
  @Value.Enclosing
  public class FilterTableScanRule
      extends RelRule<FilterTableScanRule.Config> {
    @SuppressWarnings("Guava")
    @Deprecated // to be removed before 2.0
    public static final com.google.common.base.Predicate<TableScan> PREDICATE =
        FilterTableScanRule::test;
  
    /** Creates a FilterTableScanRule. */
    protected FilterTableScanRule(Config config) {
      super(config);
    }
  
    @Deprecated // to be removed before 2.0
    protected FilterTableScanRule(RelOptRuleOperand operand, String description) {
      this(ImmutableFilterTableScanRule.Config.of().as(Config.class));
      throw new UnsupportedOperationException();
    }
  
    @Deprecated // to be removed before 2.0
    protected FilterTableScanRule(RelOptRuleOperand operand,
        RelBuilderFactory relBuilderFactory, String description) {
      this(ImmutableFilterTableScanRule.Config.of().as(Config.class));
      throw new UnsupportedOperationException();
    }
  
    //~ Methods ----------------------------------------------------------------
  
    public static boolean test(TableScan scan) {
      // We can only push filters into a FilterableTable or
      // ProjectableFilterableTable.
      final RelOptTable table = scan.getTable();
      return table.unwrap(FilterableTable.class) != null
          || table.unwrap(ProjectableFilterableTable.class) != null;
    }
  
    @Override public void onMatch(RelOptRuleCall call) {
      if (call.rels.length == 2) {
        // the ordinary variant
        final Filter filter = call.rel(0);
        final TableScan scan = call.rel(1);
        apply(call, filter, scan);
      } else if (call.rels.length == 3) {
        // the variant with intervening EnumerableInterpreter
        final Filter filter = call.rel(0);
        final TableScan scan = call.rel(2);
        apply(call, filter, scan);
      } else {
        throw new AssertionError();
      }
    }
  
    protected void apply(RelOptRuleCall call, Filter filter, TableScan scan) {
      final ImmutableIntList projects;
      final ImmutableList.Builder<RexNode> filters = ImmutableList.builder();
      if (scan instanceof Bindables.BindableTableScan) {
        final Bindables.BindableTableScan bindableScan =
            (Bindables.BindableTableScan) scan;
        filters.addAll(bindableScan.filters);
        projects = bindableScan.projects;
      } else {
        projects = scan.identity();
      }
  
      final Mapping mapping =
          Mappings.target(projects, scan.getTable().getRowType().getFieldCount());
      filters.add(
          RexUtil.apply(mapping.inverse(), filter.getCondition()));
  
      call.transformTo(
          Bindables.BindableTableScan.create(scan.getCluster(), scan.getTable(),
              filters.build(), projects));
    }
  
    /** Rule configuration. */
    @Value.Immutable
    public interface Config extends RelRule.Config {
      Config DEFAULT = ImmutableFilterTableScanRule.Config.of()
          .withOperandSupplier(b0 ->
              b0.operand(Filter.class).oneInput(b1 ->
                  b1.operand(TableScan.class)
                      .predicate(FilterTableScanRule::test).noInputs()));
  
      Config INTERPRETER = ImmutableFilterTableScanRule.Config.of()
          .withOperandSupplier(b0 ->
              b0.operand(Filter.class).oneInput(b1 ->
                  b1.operand(EnumerableInterpreter.class).oneInput(b2 ->
                      b2.operand(TableScan.class)
                          .predicate(FilterTableScanRule::test).noInputs())))
          .withDescription("FilterTableScanRule:interpreter");
  
      @Override default FilterTableScanRule toRule() {
        return new FilterTableScanRule(this);
      }
    }
  }
  