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.validate;
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.schema.Function;
  import org.apache.calcite.schema.FunctionParameter;
  import org.apache.calcite.sql.SqlFunction;
  import org.apache.calcite.sql.SqlFunctionCategory;
  import org.apache.calcite.sql.SqlIdentifier;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlSyntax;
  import org.apache.calcite.sql.type.SqlOperandMetadata;
  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.util.Util;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  /**
  * User-defined scalar function.
   *
   * <p>Created by the validator, after resolving a function call to a function
   * defined in a Calcite schema.
  */
  public class SqlUserDefinedFunction extends SqlFunction {
    public final Function function;
  
    public final SqlSyntax syntax;
  
    @Deprecated // to be removed before 2.0
    public SqlUserDefinedFunction(SqlIdentifier opName,
        SqlReturnTypeInference returnTypeInference,
        SqlOperandTypeInference operandTypeInference,
        @Nullable SqlOperandTypeChecker operandTypeChecker,
        List<RelDataType> paramTypes,
        Function function) {
      this(opName, SqlKind.OTHER_FUNCTION, returnTypeInference,
          operandTypeInference,
          operandTypeChecker instanceof SqlOperandMetadata
              ? (SqlOperandMetadata) operandTypeChecker : null, function);
      Util.discard(paramTypes); // no longer used
    }
  
    /** Creates a {@link SqlUserDefinedFunction}. */
    public SqlUserDefinedFunction(SqlIdentifier opName, SqlKind kind,
        SqlReturnTypeInference returnTypeInference,
        SqlOperandTypeInference operandTypeInference,
        @Nullable SqlOperandMetadata operandMetadata,
        Function function) {
      this(opName, kind, returnTypeInference, operandTypeInference,
          operandMetadata, function, SqlFunctionCategory.USER_DEFINED_FUNCTION, SqlSyntax.FUNCTION);
    }
  
    /** Creates a {@link SqlUserDefinedFunction} with sql syntax. */
    public SqlUserDefinedFunction(SqlIdentifier opName, SqlKind kind,
        SqlReturnTypeInference returnTypeInference,
        SqlOperandTypeInference operandTypeInference,
        @Nullable SqlOperandMetadata operandMetadata,
        Function function, SqlSyntax syntax) {
      this(opName, kind, returnTypeInference, operandTypeInference,
          operandMetadata, function, SqlFunctionCategory.USER_DEFINED_FUNCTION, syntax);
    }
  
    /** Constructor used internally and by derived classes. */
    protected SqlUserDefinedFunction(SqlIdentifier opName, SqlKind kind,
        SqlReturnTypeInference returnTypeInference,
        SqlOperandTypeInference operandTypeInference,
        @Nullable SqlOperandMetadata operandMetadata,
        Function function,
        SqlFunctionCategory category, SqlSyntax syntax) {
      super(Util.last(opName.names), opName, kind, returnTypeInference,
          operandTypeInference, operandMetadata, category);
      this.function = function;
      this.syntax = syntax;
    }
  
    @Override public @Nullable SqlOperandMetadata getOperandTypeChecker() {
      return (@Nullable SqlOperandMetadata) super.getOperandTypeChecker();
    }
  
    @Override public SqlSyntax getSyntax() {
      return syntax;
    }
  
    /**
     * Returns function that implements given operator call.
     *
     * @return function that implements given operator call
     */
    public Function getFunction() {
      return function;
    }
  
    @SuppressWarnings("deprecation")
    @Override public List<String> getParamNames() {
      return Util.transform(function.getParameters(), FunctionParameter::getName);
    }
  }
  