org.instancio.Node Maven / Gradle / Ivy

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/*
 * Copyright 2022-2024 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.instancio;

import org.instancio.settings.AssignmentType;
import org.instancio.settings.Keys;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.Optional;

/**
 * Represents a single {@code Node} of a node hierarchy
 * created for a given {@link Type}. A node can represent:
 *
 * 
 *   the root class
 *   field of a class
 *   an element of a collection, or in general, a generic type argument,
 *       for example, the type of an {@link Optional} value
 * 
 *
 * @since 2.11.0
 */
public interface Node {

    /**
     * Returns the target class of this node.
     *
     * If this node represents a field, generally the target class
     * will be the same as {@link Field#getType()}. However, there are
     * cases where the target class may differ, for example:
     *
     * 

     *   when a subtype is specified, then
     *       the node's target class will represent the subtype.
     *   when the node represents a generic type, then
     *       the target class will represent the resolved type argument.
     * 
     *
     * @return target class of this node, never {@code null}
     * @since 2.11.0
     */
    Class getTargetClass();

    /**
     * Returns the field of this node, if available.
     *
     * @return field of this node, or {@code null} if the node has no field
     * @since 2.11.0
     */
    Field getField();

    /**
     * Returns the parent of this node,
     * or {@code null} if this node is the root.
     *
     * @return parent of this node
     * @since 3.5.0
     */
    Node getParent();

    /**
     * Returns the setter of this node, if available, and if
     * {@link Keys#ASSIGNMENT_TYPE} is set to {@link AssignmentType#METHOD}.
     *
     * @return setter of this node, or {@code null} if the node has no setter
     * @since 4.0.0
     */
    Method getSetter();
}