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.type;
  
  import org.apache.calcite.sql.SqlCallBinding;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlOperator;
  import org.apache.calcite.sql.SqlUtil;
  import org.apache.calcite.util.Util;
  
  import static org.apache.calcite.util.Static.RESOURCE;
  
  /**
   * Parameter type-checking strategy type must be a literal (whether null is
   * allowed is determined by the constructor). <code>CAST(NULL as ...)</code> is
   * considered to be a NULL literal but not <code>CAST(CAST(NULL as ...) AS
   * ...)</code>
   */
  public class LiteralOperandTypeChecker implements SqlSingleOperandTypeChecker {
    //~ Instance fields --------------------------------------------------------
  
    private final boolean allowNull;
  
    //~ Constructors -----------------------------------------------------------
  
    public LiteralOperandTypeChecker(boolean allowNull) {
      this.allowNull = allowNull;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public boolean checkSingleOperandType(
        SqlCallBinding callBinding,
        SqlNode node,
        int iFormalOperand,
        boolean throwOnFailure) {
      Util.discard(iFormalOperand);
  
      if (SqlUtil.isNullLiteral(node, true)) {
        if (allowNull) {
          return true;
        }
        if (throwOnFailure) {
          throw callBinding.newError(
              RESOURCE.argumentMustNotBeNull(
                  callBinding.getOperator().getName()));
        }
        return false;
      }
      if (!SqlUtil.isLiteral(node) && !SqlUtil.isLiteralChain(node)) {
        if (throwOnFailure) {
          throw callBinding.newError(
              RESOURCE.argumentMustBeLiteral(
                  callBinding.getOperator().getName()));
        }
        return false;
      }
  
      return true;
    }
  
    @Override public String getAllowedSignatures(SqlOperator op, String opName) {
      return "<LITERAL>";
    }
  }
  