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/*
* Copyright 2002-2024 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
*
* https://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;
import org.jspecify.annotations.Nullable;
/**
* Strategy for types that access elements of specific target classes.
*
* This interface places no restrictions on what constitutes an element.
*
*
A targeted accessor can specify a set of target classes for which it should
* be called. However, if it returns {@code null} or an empty array from
* {@link #getSpecificTargetClasses()}, it will typically be called for all
* access operations and given a chance to determine if it supports a concrete
* access attempt.
*
*
Targeted accessors are considered to be ordered, and each will be called
* in turn. The only rule that affects the call order is that any accessor which
* specifies explicit support for a given target type via
* {@link #getSpecificTargetClasses()} will be called first, before other generic
* accessors that do not specify support for explicit target types. In addition,
* accessors that support the exact target type will be called before accessors
* that support a supertype of the target type.
*
* @author Sam Brannen
* @since 6.2
* @see PropertyAccessor
* @see IndexAccessor
*/
public interface TargetedAccessor {
/**
* Get the set of classes for which this accessor should be called.
*
Returning {@code null} or an empty array indicates this is a generic
* accessor that can be called in an attempt to access an element on any
* type.
* @return an array of classes that this accessor is suitable for
* (or {@code null} or an empty array if a generic accessor)
*/
Class @Nullable [] getSpecificTargetClasses();
}