org.springframework.expression.IndexAccessor Maven / Gradle / Ivy
Show all versions of spring-expression Show documentation
/*
* 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;
/**
* An index accessor is able to read from and possibly write to an indexed
* structure of a target object.
*
* This interface places no restrictions on what constitutes an indexed
* structure. Implementors are therefore free to access indexed values any way
* they deem appropriate.
*
*
An index accessor can specify an array of
* {@linkplain #getSpecificTargetClasses() target classes} for which it should be
* called. See {@link TargetedAccessor} for details.
*
* @author Jackmiking Lee
* @author Sam Brannen
* @since 6.2
* @see TargetedAccessor
* @see PropertyAccessor
*/
public interface IndexAccessor extends TargetedAccessor {
/**
* Determine if this index accessor is able to read a specified index on a
* specified target object.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the index is being accessed
* @param index the index being accessed
* @return {@code true} if this index accessor is able to read the index
* @throws AccessException if there is any problem determining whether the
* index can be read
*/
boolean canRead(EvaluationContext context, Object target, Object index) throws AccessException;
/**
* Read an index from a specified target object.
*
Should only be invoked if {@link #canRead} returns {@code true} for the
* same arguments.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the index is being accessed
* @param index the index being accessed
* @return a TypedValue object wrapping the index value read and a type
* descriptor for the value
* @throws AccessException if there is any problem reading the index
*/
TypedValue read(EvaluationContext context, Object target, Object index) throws AccessException;
/**
* Determine if this index accessor is able to write to a specified index on
* a specified target object.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the index is being accessed
* @param index the index being accessed
* @return {@code true} if this index accessor is able to write to the index
* @throws AccessException if there is any problem determining whether the
* index can be written to
*/
boolean canWrite(EvaluationContext context, Object target, Object index) throws AccessException;
/**
* Write to an index on a specified target object.
*
Should only be invoked if {@link #canWrite} returns {@code true} for the
* same arguments.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the index is being accessed
* @param index the index being accessed
* @param newValue the new value for the index
* @throws AccessException if there is any problem writing to the index
*/
void write(EvaluationContext context, Object target, Object index, @Nullable Object newValue)
throws AccessException;
}