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.sql;
  
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.ReturnTypes;
  import org.apache.calcite.sql.type.SqlOperandTypeChecker;
  import org.apache.calcite.sql.type.SqlOperandTypeInference;
  import org.apache.calcite.sql.type.SqlReturnTypeInference;
  import org.apache.calcite.sql.validate.SqlValidator;
  import org.apache.calcite.sql.validate.SqlValidatorScope;
  
  /**
   * SqlSetOperator represents a relational set theory operator (UNION, INTERSECT,
   * MINUS). These are binary operators, but with an extra boolean attribute
   * tacked on for whether to remove duplicates (e.g. UNION ALL does not remove
   * duplicates).
   */
  public class SqlSetOperator extends SqlBinaryOperator {
    //~ Instance fields --------------------------------------------------------
  
    private final boolean all;
  
    //~ Constructors -----------------------------------------------------------
  
    public SqlSetOperator(
        String name,
        SqlKind kind,
        int prec,
        boolean all) {
      super(
          name,
          kind,
          prec,
          true,
          ReturnTypes.LEAST_RESTRICTIVE,
          null,
          OperandTypes.SET_OP);
      this.all = all;
    }
  
    public SqlSetOperator(
        String name,
        SqlKind kind,
        int prec,
        boolean all,
        SqlReturnTypeInference returnTypeInference,
        SqlOperandTypeInference operandTypeInference,
        SqlOperandTypeChecker operandTypeChecker) {
      super(
          name,
          kind,
          prec,
          true,
          returnTypeInference,
          operandTypeInference,
          operandTypeChecker);
      this.all = all;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    public boolean isAll() {
      return all;
    }
  
    public boolean isDistinct() {
      return !all;
    }
  
    @Override public void validateCall(
        SqlCall call,
        SqlValidator validator,
        SqlValidatorScope scope,
        SqlValidatorScope operandScope) {
      validator.validateQuery(call, operandScope, validator.getUnknownType());
    }
  }
  