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.avatica.util.TimeUnit;
  import org.apache.calcite.sql.SqlCall;
  import org.apache.calcite.sql.SqlCallBinding;
  import org.apache.calcite.sql.SqlFunction;
  import org.apache.calcite.sql.SqlFunctionCategory;
  import org.apache.calcite.sql.SqlIntervalQualifier;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlOperandCountRange;
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.sql.type.InferTypes;
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.ReturnTypes;
  import org.apache.calcite.sql.type.SqlOperandCountRanges;
  import org.apache.calcite.sql.validate.SqlValidator;
  
  import java.util.List;
  
  import static org.apache.calcite.util.Static.RESOURCE;
  
  /**
   * SqlDatePartFunction represents the SQL:1999 standard {@code YEAR},
   * {@code QUARTER}, {@code MONTH} and {@code DAY} functions.
   */
  public class SqlDatePartFunction extends SqlFunction {
    //~ Constructors -----------------------------------------------------------
    private final TimeUnit timeUnit;
  
    public SqlDatePartFunction(String name, TimeUnit timeUnit) {
      super(name,
          SqlKind.OTHER,
          ReturnTypes.BIGINT_NULLABLE,
          InferTypes.FIRST_KNOWN,
          OperandTypes.DATETIME,
          SqlFunctionCategory.TIMEDATE);
      this.timeUnit = timeUnit;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public SqlNode rewriteCall(SqlValidator validator, SqlCall call) {
      final List<SqlNode> operands = call.getOperandList();
  
      if (operands.size() != 1) {
        throw validator.newValidationError(call, RESOURCE.invalidArgCount(getName(), 1));
      }
  
      final SqlParserPos pos = call.getParserPosition();
      return SqlStdOperatorTable.EXTRACT.createCall(pos,
          new SqlIntervalQualifier(timeUnit, null, SqlParserPos.ZERO),
          operands.get(0));
    }
  
    @Override public SqlOperandCountRange getOperandCountRange() {
      return SqlOperandCountRanges.of(1);
    }
  
    @Override public String getSignatureTemplate(int operandsCount) {
      assert 1 == operandsCount;
      return "{0}({1})";
    }
  
    @Override public boolean checkOperandTypes(SqlCallBinding callBinding,
        boolean throwOnFailure) {
      // Use #checkOperandTypes instead of #checkSingleOperandType to enable implicit
      // type coercion. REVIEW Danny 2019-09-10, because we declare that the operand
      // type family is DATETIME, that means it allows arguments of type DATE, TIME
      // or TIMESTAMP, so actually we can not figure out which type we want precisely.
      // For example, the YEAR(date) function, it actually allows a DATE/TIMESTAMP operand,
      // but we declare the required operand type family to be DATETIME.
      // We just need some refactoring for the SqlDatePartFunction.
      return OperandTypes.DATETIME.checkOperandTypes(callBinding, throwOnFailure);
    }
  }
  