| /* |
| * 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.flink.table.expressions; |
| |
| import org.apache.flink.annotation.Internal; |
| |
| import java.util.Optional; |
| |
| /** Utility methods for working with {@link Expression}s. */ |
| @Internal |
| public final class ExpressionUtils { |
| |
| /** |
| * Extracts the value (excluding null) of a given class from an expression assuming it is a |
| * {@link ValueLiteralExpression}. |
| * |
| * @param expression literal to extract the value from |
| * @param targetClass expected class to extract from the literal |
| * @param <V> type of extracted value |
| * @return extracted value or empty if could not extract value of given type |
| */ |
| public static <V> Optional<V> extractValue(Expression expression, Class<V> targetClass) { |
| if (expression instanceof ValueLiteralExpression) { |
| final ValueLiteralExpression valueLiteral = (ValueLiteralExpression) expression; |
| return valueLiteral.getValueAs(targetClass); |
| } |
| return Optional.empty(); |
| } |
| |
| private ExpressionUtils() {} |
| } |
