Implement Chen Notation for ER-diagrams

src/net/sourceforge/plantuml/PSystemBuilder.java

@@ -48,6 +48,7 @@
 import net.sourceforge.plantuml.api.PSystemFactory;
 import net.sourceforge.plantuml.board.BoardDiagramFactory;
 import net.sourceforge.plantuml.bpm.BpmDiagramFactory;
+import net.sourceforge.plantuml.cheneer.ChenEerDiagramFactory;
 import net.sourceforge.plantuml.chronology.ChronologyDiagramFactory;
 import net.sourceforge.plantuml.classdiagram.ClassDiagramFactory;
 import net.sourceforge.plantuml.core.Diagram;
@@ -277,6 +278,8 @@ final public Diagram createPSystem(List<StringLocated> source, List<StringLocate
 		factories.add(new HclDiagramFactory());
 		factories.add(new PSystemEbnfFactory());
 		factories.add(new PSystemRegexFactory());
+
+		factories.add(new ChenEerDiagramFactory());
 	}
 
 	private boolean isOk(Diagram ps) {

src/net/sourceforge/plantuml/abel/LeafType.java

@@ -62,6 +62,8 @@ public enum LeafType {
 
 	PORTIN, PORTOUT,
 
+	CHEN_ENTITY, CHEN_RELATIONSHIP, CHEN_ATTRIBUTE, CHEN_CIRCLE,
+
 	STILL_UNKNOWN;
 
 	public static LeafType getLeafType(String type) {

src/net/sourceforge/plantuml/cheneer/ChenEerDiagram.java

@@ -0,0 +1,95 @@
+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * (C) Copyright 2009-2024, Arnaud Roques
+ *
+ * Project Info:  https://plantuml.com
+ * 
+ * If you like this project or if you find it useful, you can support us at:
+ * 
+ * https://plantuml.com/patreon (only 1$ per month!)
+ * https://plantuml.com/paypal
+ * 
+ * This file is part of PlantUML.
+ *
+ * PlantUML is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlantUML distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ *
+ * Original Author:  Arnaud Roques
+ *
+ */
+package net.sourceforge.plantuml.cheneer;
+
+import java.util.Map;
+import java.util.Stack;
+
+import net.sourceforge.plantuml.abel.Entity;
+import net.sourceforge.plantuml.classdiagram.AbstractEntityDiagram;
+import net.sourceforge.plantuml.core.UmlSource;
+import net.sourceforge.plantuml.skin.UmlDiagramType;
+
+public class ChenEerDiagram extends AbstractEntityDiagram {
+
+	public ChenEerDiagram(UmlSource source, Map<String, String> skinParam) {
+		super(source, UmlDiagramType.CHEN_EER, skinParam);
+	}
+
+	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();
+	}
+
+}

src/net/sourceforge/plantuml/cheneer/ChenEerDiagramFactory.java

@@ -0,0 +1,78 @@
+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * (C) Copyright 2009-2024, Arnaud Roques
+ *
+ * Project Info:  https://plantuml.com
+ * 
+ * If you like this project or if you find it useful, you can support us at:
+ * 
+ * https://plantuml.com/patreon (only 1$ per month!)
+ * https://plantuml.com/paypal
+ * 
+ * This file is part of PlantUML.
+ *
+ * PlantUML is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlantUML distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ *
+ * Original Author:  Arnaud Roques
+ * 
+ *
+ */
+package net.sourceforge.plantuml.cheneer;
+
+import java.util.List;
+import java.util.Map;
+
+import net.sourceforge.plantuml.AbstractPSystem;
+import net.sourceforge.plantuml.cheneer.command.CommandAssociate;
+import net.sourceforge.plantuml.cheneer.command.CommandCreateAttribute;
+import net.sourceforge.plantuml.cheneer.command.CommandCreateEntity;
+import net.sourceforge.plantuml.cheneer.command.CommandEndGroup;
+import net.sourceforge.plantuml.cheneer.command.CommandMultiSubclass;
+import net.sourceforge.plantuml.cheneer.command.CommandSimpleSubclass;
+import net.sourceforge.plantuml.command.Command;
+import net.sourceforge.plantuml.command.CommonCommands;
+import net.sourceforge.plantuml.command.PSystemCommandFactory;
+import net.sourceforge.plantuml.core.DiagramType;
+import net.sourceforge.plantuml.core.UmlSource;
+
+public class ChenEerDiagramFactory extends PSystemCommandFactory {
+
+	public ChenEerDiagramFactory() {
+		super(DiagramType.CHEN_EER);
+	}
+
+	@Override
+	protected void initCommandsList(List<Command> cmds) {
+		CommonCommands.addTitleCommands(cmds);
+		CommonCommands.addCommonCommands2(cmds);
+
+		cmds.add(new CommandCreateEntity());
+		cmds.add(new CommandCreateAttribute());
+		cmds.add(new CommandAssociate());
+		cmds.add(new CommandEndGroup());
+		cmds.add(new CommandSimpleSubclass());
+		cmds.add(new CommandMultiSubclass());
+	}
+
+	@Override
+	public AbstractPSystem createEmptyDiagram(UmlSource source, Map<String, String> skinParam) {
+		return new ChenEerDiagram(source, skinParam);
+	}
+
+}

src/net/sourceforge/plantuml/cheneer/command/CommandAssociate.java

@@ -0,0 +1,108 @@
+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * (C) Copyright 2009-2024, Arnaud Roques
+ *
+ * Project Info:  https://plantuml.com
+ *
+ * If you like this project or if you find it useful, you can support us at:
+ *
+ * https://plantuml.com/patreon (only 1$ per month!)
+ * https://plantuml.com/paypal
+ *
+ * This file is part of PlantUML.
+ *
+ * PlantUML is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlantUML distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ *
+ * Original Author:  Arnaud Roques
+ *
+ *
+ */
+package net.sourceforge.plantuml.cheneer.command;
+
+import net.sourceforge.plantuml.abel.Entity;
+import net.sourceforge.plantuml.abel.Link;
+import net.sourceforge.plantuml.abel.LinkArg;
+import net.sourceforge.plantuml.cheneer.ChenEerDiagram;
+import net.sourceforge.plantuml.command.CommandExecutionResult;
+import net.sourceforge.plantuml.command.SingleLineCommand2;
+import net.sourceforge.plantuml.decoration.LinkDecor;
+import net.sourceforge.plantuml.decoration.LinkType;
+import net.sourceforge.plantuml.klimt.color.NoSuchColorException;
+import net.sourceforge.plantuml.klimt.creole.Display;
+import net.sourceforge.plantuml.plasma.Quark;
+import net.sourceforge.plantuml.regex.IRegex;
+import net.sourceforge.plantuml.regex.RegexConcat;
+import net.sourceforge.plantuml.regex.RegexLeaf;
+import net.sourceforge.plantuml.regex.RegexOptional;
+import net.sourceforge.plantuml.regex.RegexResult;
+import net.sourceforge.plantuml.utils.LineLocation;
+
+public class CommandAssociate extends SingleLineCommand2<ChenEerDiagram> {
+
+	public CommandAssociate() {
+		super(getRegexConcat());
+	}
+
+	protected static IRegex getRegexConcat() {
+		return RegexConcat.build(CommandCreateEntity.class.getName(), RegexLeaf.start(), //
+				new RegexLeaf("NAME1", "([\\w-]+)"), //
+				RegexLeaf.spaceZeroOrMore(), //
+				new RegexLeaf("PARTICIPATION", "([-=])"), //
+				new RegexOptional( //
+						new RegexLeaf("CARDINALITY", "(\\w+|\\(\\w+,[%s]*\\w+\\))")), //
+				new RegexLeaf("PARTICIPATION2", "([-=])"), //
+				RegexLeaf.spaceZeroOrMore(), //
+				new RegexLeaf("NAME2", "([\\w-]+)"), //
+				RegexLeaf.end());
+	}
+
+	@Override
+	protected CommandExecutionResult executeArg(ChenEerDiagram diagram, LineLocation location, RegexResult arg)
+			throws NoSuchColorException {
+		final String name1 = diagram.cleanId(arg.get("NAME1", 0));
+		final String name2 = diagram.cleanId(arg.get("NAME2", 0));
+		final boolean isDouble = arg.get("PARTICIPATION", 0).equals("=");
+		final String cardinality = arg.get("CARDINALITY", 0);
+
+		final Quark<Entity> quark1 = diagram.quarkInContext(true, name1);
+		final Entity entity1 = quark1.getData();
+		if (entity1 == null) {
+			return CommandExecutionResult.error("No such entity: " + name1);
+		}
+
+		final Quark<Entity> quark2 = diagram.quarkInContext(true, name2);
+		final Entity entity2 = quark2.getData();
+		if (entity2 == null) {
+			return CommandExecutionResult.error("No such entity: " + name2);
+		}
+
+		LinkType linkType = new LinkType(LinkDecor.NONE, LinkDecor.NONE);
+		if (isDouble) {
+			linkType = linkType.goBold();
+		}
+		final Link link = new Link(diagram.getEntityFactory(), diagram.getCurrentStyleBuilder(), entity1, entity2,
+				linkType,
+				LinkArg.build(Display.getWithNewlines(cardinality), 3));
+		link.setPortMembers(diagram.getPortId(entity1.getName()), diagram.getPortId(entity2.getName()));
+		diagram.addLink(link);
+
+		return CommandExecutionResult.ok();
+	}
+
+}