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.plan.RelOptRuleCall;
  import org.apache.calcite.plan.RelRule;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.JoinRelType;
  import org.apache.calcite.rel.core.Minus;
  import org.apache.calcite.rel.logical.LogicalMinus;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rex.RexBuilder;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.rex.RexUtil;
  import org.apache.calcite.tools.RelBuilder;
  
  import org.immutables.value.Value;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Planner rule that translates a {@link Minus}
   * to a series of {@link org.apache.calcite.rel.core.Join} that type is
   * {@link JoinRelType#ANTI}. This rule supports n-way Minus conversion,
   * as this rule can be repeatedly applied during query optimization to
   * refine the plan.
   *
   * <p>Example for 2-way
   *
   * <p>Original sql:
   * <pre>{@code
   * select ename from emp where deptno = 10
   * except
   * select ename from emp where deptno = 20
   * }</pre>
   *
   * <p>Original plan:
   * <pre>{@code
   * LogicalMinus(all=[false])
   *   LogicalProject(ENAME=[$1])
   *     LogicalFilter(condition=[=($7, 10)])
   *       LogicalTableScan(table=[[CATALOG, SALES, EMP]])
   *   LogicalProject(ENAME=[$1])
   *     LogicalFilter(condition=[=($7, 20)])
   * }</pre>
   *
   * <p>Plan after conversion:
   * <pre>{@code
   * LogicalAggregate(group=[{0}])
   *   LogicalJoin(condition=[IS NOT DISTINCT FROM($0, $1)], joinType=[anti])
   *     LogicalProject(ENAME=[$1])
   *       LogicalFilter(condition=[=($7, 10)])
   *         LogicalTableScan(table=[[CATALOG, SALES, EMP]])
   *     LogicalProject(ENAME=[$1])
   *       LogicalFilter(condition=[=($7, 20)])
   *         LogicalTableScan(table=[[CATALOG, SALES, EMP]])
   * }</pre>
   *
   * <p>Example for n-way
   *
   * <p>Original sql:
   * <pre>{@code
   * select ename from emp where deptno = 10
   * except
   * select deptno from emp where ename in ('a', 'b')
   * except
   * select ename from empnullables
   * }</pre>
   *
   * <p>Original plan:
   * <pre>{@code
   * LogicalMinus(all=[false])
   *   LogicalProject(ENAME=[$1])
   *     LogicalFilter(condition=[=($7, 10)])
   *       LogicalTableScan(table=[[CATALOG, SALES, EMP]])
   *   LogicalProject(DEPTNO=[CAST($7):VARCHAR NOT NULL])
   *     LogicalFilter(condition=[OR(=($1, 'a'), =($1, 'b'))])
   *       LogicalTableScan(table=[[CATALOG, SALES, EMP]])
   *   LogicalProject(ENAME=[$1])
   *     LogicalTableScan(table=[[CATALOG, SALES, EMPNULLABLES]])
   * }</pre>
   *
   * <p>Plan after conversion:
   * <pre>{@code
   * LogicalProject(ENAME=[CAST($0):VARCHAR])
   *   LogicalAggregate(group=[{0}])
   *     LogicalJoin(condition=[<=>(CAST($0):VARCHAR, CAST($1):VARCHAR)], joinType=[anti])
   *       LogicalJoin(condition=[=(CAST($0):VARCHAR, $1)], joinType=[anti])
   *         LogicalProject(ENAME=[$1])
   *           LogicalFilter(condition=[=($7, 10)])
   *             LogicalTableScan(table=[[CATALOG, SALES, EMP]])
   *         LogicalProject(DEPTNO=[CAST($7):VARCHAR NOT NULL])
   *           LogicalFilter(condition=[OR(=($1, 'a'), =($1, 'b'))])
   *             LogicalTableScan(table=[[CATALOG, SALES, EMP]])
   *       LogicalProject(ENAME=[$1])
   *         LogicalTableScan(table=[[CATALOG, SALES, EMPNULLABLES]])
   * }</pre>
   */
  @Value.Enclosing
  public class MinusToAntiJoinRule
      extends RelRule<MinusToAntiJoinRule.Config>
      implements TransformationRule {
  
    /** Creates an MinusToAntiJoinRule. */
    protected MinusToAntiJoinRule(Config config) {
      super(config);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void onMatch(RelOptRuleCall call) {
      final Minus minus = call.rel(0);
      if (minus.all) {
        return; // nothing we can do
      }
  
      List<RelNode> inputs = minus.getInputs();
      if (inputs.size() < 2) {
        return;
      }
  
      final RelBuilder relBuilder = call.builder();
      final RexBuilder rexBuilder = relBuilder.getRexBuilder();
  
      final RelDataType leastRowType = minus.getRowType();
      RelNode current = inputs.get(0);
      relBuilder.push(current);
  
      for (int i = 1; i < inputs.size(); i++) {
        RelNode next = inputs.get(i);
        int fieldCount = current.getRowType().getFieldCount();
  
        List<RexNode> conditions = new ArrayList<>();
        for (int j = 0; j < fieldCount; j++) {
          RelDataType leftFieldType = current.getRowType().getFieldList().get(j).getType();
          RelDataType rightFieldType = next.getRowType().getFieldList().get(j).getType();
          RelDataType leastFieldType = leastRowType.getFieldList().get(j).getType();
  
          conditions.add(
              relBuilder.isNotDistinctFrom(
                  rexBuilder.makeCast(leastFieldType,
                      rexBuilder.makeInputRef(leftFieldType, j)),
                  rexBuilder.makeCast(leastFieldType,
                      rexBuilder.makeInputRef(rightFieldType, j + fieldCount))));
        }
        RexNode condition = RexUtil.composeConjunction(rexBuilder, conditions);
  
        relBuilder.push(next)
            .join(JoinRelType.ANTI, condition);
  
        current = relBuilder.peek();
      }
  
      relBuilder.distinct()
          .convert(leastRowType, true);
      call.transformTo(relBuilder.build());
    }
  
    /** Rule configuration. */
    @Value.Immutable
    public interface Config extends RelRule.Config {
      Config DEFAULT = ImmutableMinusToAntiJoinRule.Config.of()
          .withOperandFor(LogicalMinus.class);
  
      @Override default MinusToAntiJoinRule toRule() {
        return new MinusToAntiJoinRule(this);
      }
  
      /** Defines an operand tree for the given classes. */
      default Config withOperandFor(Class<? extends Minus> minusClass) {
        return withOperandSupplier(b -> b.operand(minusClass).anyInputs())
            .as(Config.class);
      }
    }
  }
  