/*
* Copyright 2002-2009 the original author or authors.
*
* Licensed 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.springframework.expression;
/**
* By default the mathematical operators {@link Operation} support simple types like numbers. By providing an
* implementation of OperatorOverloader, a user of the expression language can support these operations on other types.
*
* @author Andy Clement
* @since 3.0
*/
public interface OperatorOverloader {
/**
* Return true if the operator overloader supports the specified operation
* between the two operands and so should be invoked to handle it.
* @param operation the operation to be performed
* @param leftOperand the left operand
* @param rightOperand the right operand
* @return true if the OperatorOverloader supports the specified operation between the two operands
* @throws EvaluationException if there is a problem performing the operation
*/
boolean overridesOperation(Operation operation, Object leftOperand, Object rightOperand)
throws EvaluationException;
/**
* Execute the specified operation on two operands, returning a result.
* See {@link Operation} for supported operations.
* @param operation the operation to be performed
* @param leftOperand the left operand
* @param rightOperand the right operand
* @return the result of performing the operation on the two operands
* @throws EvaluationException if there is a problem performing the operation
*/
Object operate(Operation operation, Object leftOperand, Object rightOperand)
throws EvaluationException;
}
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