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.SqlFunction;
  import org.apache.calcite.sql.SqlFunctionCategory;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlWriter;
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.ReturnTypes;
  import org.apache.calcite.sql.type.SqlOperandTypeChecker;
  
  /**
   * The <code>OVERLAY</code> function.
   */
  public class SqlOverlayFunction extends SqlFunction {
    //~ Static fields/initializers ---------------------------------------------
  
    private static final SqlOperandTypeChecker OTC_CUSTOM =
        OperandTypes.STRING_STRING_INTEGER
            .or(OperandTypes.STRING_STRING_INTEGER_INTEGER);
  
    //~ Constructors -----------------------------------------------------------
  
    public SqlOverlayFunction() {
      super(
          "OVERLAY",
          SqlKind.OTHER_FUNCTION,
          ReturnTypes.DYADIC_STRING_SUM_PRECISION_NULLABLE_VARYING,
          null,
          OTC_CUSTOM,
          SqlFunctionCategory.STRING);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void unparse(
        SqlWriter writer,
        SqlCall call,
        int leftPrec,
        int rightPrec) {
      final SqlWriter.Frame frame = writer.startFunCall(getName());
      call.operand(0).unparse(writer, leftPrec, rightPrec);
      writer.sep("PLACING");
      call.operand(1).unparse(writer, leftPrec, rightPrec);
      writer.sep("FROM");
      call.operand(2).unparse(writer, leftPrec, rightPrec);
      if (4 == call.operandCount()) {
        writer.sep("FOR");
        call.operand(3).unparse(writer, leftPrec, rightPrec);
      }
      writer.endFunCall(frame);
    }
  
    @Override public String getSignatureTemplate(final int operandsCount) {
      switch (operandsCount) {
      case 3:
        return "{0}({1} PLACING {2} FROM {3})";
      case 4:
        return "{0}({1} PLACING {2} FROM {3} FOR {4})";
      default:
        throw new IllegalArgumentException("operandsCount should be 3 or 4, got " + operandsCount);
      }
    }
  }
  