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.fun;
  
  import org.apache.calcite.sql.SqlCall;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlOperatorBinding;
  import org.apache.calcite.sql.SqlSpecialOperator;
  import org.apache.calcite.sql.SqlWriter;
  import org.apache.calcite.sql.type.InferTypes;
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.SqlReturnTypeInference;
  import org.apache.calcite.sql.validate.SqlMonotonicity;
  
  /**
   * A special operator for the subtraction of two DATETIMEs. The format of
   * DATETIME subtraction is:
   *
   * <blockquote><code>"(" &lt;datetime&gt; "-" &lt;datetime&gt; ")"
   * &lt;interval qualifier&gt;</code></blockquote>
   *
   * <p>This operator is special since it needs to hold the
   * additional interval qualifier specification, when in {@link SqlCall} form.
   * In {@link org.apache.calcite.rex.RexNode} form, it has only two parameters,
   * and the return type describes the desired type of interval.
   *
   * <p>When being used for BigQuery's {@code TIMESTAMP_SUB}, {@code TIME_SUB},
   * and {@code DATE_SUB} operators, this operator subtracts an interval value
   * from a timestamp value. The return type differs due to differing number of
   * parameters and ordering. This is accounted for by passing in a
   * {@link SqlReturnTypeInference} which is passed in by
   * the standard {@link SqlStdOperatorTable#MINUS_DATE MINUS_DATE}
   * and the library {@link SqlInternalOperators#MINUS_DATE2 MINUS_DATE2}
   * operators at their respective initializations.
   */
  public class SqlDatetimeSubtractionOperator extends SqlSpecialOperator {
    //~ Constructors -----------------------------------------------------------
  
    public SqlDatetimeSubtractionOperator(String name,
        SqlReturnTypeInference returnTypeInference) {
      super("-", SqlKind.MINUS, 40, true, returnTypeInference,
          InferTypes.FIRST_KNOWN, OperandTypes.MINUS_DATE_OPERATOR);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void unparse(
        SqlWriter writer,
        SqlCall call,
        int leftPrec,
        int rightPrec) {
      writer.getDialect().unparseSqlDatetimeArithmetic(
          writer, call, SqlKind.MINUS, leftPrec, rightPrec);
    }
  
    @Override public SqlMonotonicity getMonotonicity(SqlOperatorBinding call) {
      return SqlStdOperatorTable.MINUS.getMonotonicity(call);
    }
  }
  