001/* 002 * Copyright 2002-2017 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.expression; 018 019import org.springframework.lang.Nullable; 020 021/** 022 * By default the mathematical operators {@link Operation} support simple types 023 * like numbers. By providing an implementation of OperatorOverloader, a user 024 * of the expression language can support these operations on other types. 025 * 026 * @author Andy Clement 027 * @since 3.0 028 */ 029public interface OperatorOverloader { 030 031 /** 032 * Return true if the operator overloader supports the specified operation 033 * between the two operands and so should be invoked to handle it. 034 * @param operation the operation to be performed 035 * @param leftOperand the left operand 036 * @param rightOperand the right operand 037 * @return true if the OperatorOverloader supports the specified operation 038 * between the two operands 039 * @throws EvaluationException if there is a problem performing the operation 040 */ 041 boolean overridesOperation(Operation operation, @Nullable Object leftOperand, @Nullable Object rightOperand) 042 throws EvaluationException; 043 044 /** 045 * Execute the specified operation on two operands, returning a result. 046 * See {@link Operation} for supported operations. 047 * @param operation the operation to be performed 048 * @param leftOperand the left operand 049 * @param rightOperand the right operand 050 * @return the result of performing the operation on the two operands 051 * @throws EvaluationException if there is a problem performing the operation 052 */ 053 Object operate(Operation operation, @Nullable Object leftOperand, @Nullable Object rightOperand) 054 throws EvaluationException; 055 056}