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Core YAML 1.2 parser and emitter for Java

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/*
 * Copyright (c) 2018, SnakeYAML
 *
 * 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.snakeyaml.engine.v2.api;

import org.snakeyaml.engine.v2.exceptions.YamlEngineException;
import org.snakeyaml.engine.v2.nodes.Node;

/**
 * Provide a way to construct a Java instance from the composed Node. Support recursive objects if
 * it is required. (create Native Data Structure out of Node Graph) (this is the opposite for
 * Represent)
 *
 * @see Processing Overview
 */
public interface ConstructNode {

  /**
   * Construct a Java instance with all the properties injected when it is possible.
   *
   * @param node composed Node
   * @return a complete Java instance or empty collection instance if it is recursive
   */
  Object construct(Node node);

  /**
   * Apply the second step when constructing recursive structures. Because the instance is already
   * created it can assign a reference to itself. (no need to implement this method for
   * non-recursive data structures). Fail with a reminder to provide the second step for a recursive
   * structure
   *
   * @param node composed Node
   * @param object the instance constructed earlier by construct(Node node) for the
   *        provided Node
   */
  default void constructRecursive(Node node, Object object) {
    if (node.isRecursive()) {
      throw new IllegalStateException("Not implemented in " + getClass().getName());
    } else {
      throw new YamlEngineException("Unexpected recursive structure for Node: " + node);
    }
  }
}