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; 018 019/** 020 * By default the mathematical operators {@link Operation} support simple types 021 * like numbers. By providing an implementation of OperatorOverloader, a user 022 * of the expression language can support these operations on other types. 023 * 024 * @author Andy Clement 025 * @since 3.0 026 */ 027public interface OperatorOverloader { 028 029 /** 030 * Return true if the operator overloader supports the specified operation 031 * between the two operands and so should be invoked to handle it. 032 * @param operation the operation to be performed 033 * @param leftOperand the left operand 034 * @param rightOperand the right operand 035 * @return true if the OperatorOverloader supports the specified operation 036 * between the two operands 037 * @throws EvaluationException if there is a problem performing the operation 038 */ 039 boolean overridesOperation(Operation operation, Object leftOperand, Object rightOperand) 040 throws EvaluationException; 041 042 /** 043 * Execute the specified operation on two operands, returning a result. 044 * See {@link Operation} for supported operations. 045 * @param operation the operation to be performed 046 * @param leftOperand the left operand 047 * @param rightOperand the right operand 048 * @return the result of performing the operation on the two operands 049 * @throws EvaluationException if there is a problem performing the operation 050 */ 051 Object operate(Operation operation, Object leftOperand, Object rightOperand) 052 throws EvaluationException; 053 054}