ChenEerDiagram.java

/* ========================================================================
 * PlantUML : a free UML diagram generator
 * ========================================================================
 *
 * (C) Copyright 2009-2024, Arnaud Roques
 *
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 * Original Author:  Arnaud Roques
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package net.sourceforge.plantuml.cheneer;

import java.util.Stack;

import net.sourceforge.plantuml.Previous;
import net.sourceforge.plantuml.abel.Entity;
import net.sourceforge.plantuml.classdiagram.AbstractEntityDiagram;
import net.sourceforge.plantuml.core.UmlSource;
import net.sourceforge.plantuml.preproc.PreprocessingArtifact;
import net.sourceforge.plantuml.skin.UmlDiagramType;

public class ChenEerDiagram extends AbstractEntityDiagram {

	public ChenEerDiagram(UmlSource source, Previous previous, PreprocessingArtifact preprocessingArtifact) {
		super(source, UmlDiagramType.CHEN_EER, previous, preprocessingArtifact);
	}

	private final Stack<Entity> ownerStack = new Stack<Entity>();

	/**
	 * Pushes the owner of the following attributes.
	 *
	 * @see #peekOwner()
	 * @param group the entity that owns the following attributes
	 */
	public void pushOwner(Entity group) {
		ownerStack.push(group);
	}

	/**
	 * Pops an attribute owner from the stack. See also {@link #peekOwner()}.
	 *
	 * @see #peekOwner()
	 * @return true if an owner was popped, false if the stack was empty
	 */
	public boolean popOwner() {
		if (ownerStack.isEmpty()) {
			return false;
		}
		ownerStack.pop();
		return true;
	}

	/**
	 * Returns the owner of the current attribute.
	 *
	 * <p>
	 * This is used to link attributes based on their lexical position (how they
	 * appear in sources) without nesting the entities (like how packages are
	 * done). It is for this reason that we can't use CucaDiagram.getCurrentGroup,
	 * as that method nests the entities.
	 *
	 * @return the owner of the current attribute, or null if there is no owner
	 */
	public Entity peekOwner() {
		if (ownerStack.isEmpty()) {
			return null;
		}
		return ownerStack.peek();
	}

}