[2097] Handle expressions in SysON

Bug: #2097
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>

Author: pcdavid

CHANGELOG.adoc

@@ -24,6 +24,8 @@
 - https://github.com/eclipse-syson/syson/issues/2116[#2116] [explorer] In the _Explorer_ view, the items corresponding to the internals of `Expression` elements (syntax tree) are now hidden by default.
 Disabling the _Hide expression internals_ filter in the _Explorer_ view allows to display them if needed.
 - https://github.com/eclipse-syson/syson/issues/2112[#2112] [diagrams] Add tools to create _Start_ and _Done_ `StateUsages`, available on `StateUsage` and `StateDefinition` graphical nodes.
+- https://github.com/eclipse-syson/syson/issues/2097[#2097] [explorer] Add support for creating and editing exressions through their textual representation.
+This is currently supported on `Features` (e.g. `Attribute`), `Constraints` and `Transitions` (guard conditions) view new context menu actions (_Create expression_ and _Edit expression_) on the corresponding elements in the _Explorer_.
 
 == v2026.5.0
 

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/configuration/SysMLv2PropertiesConfigurer.java

@@ -25,7 +25,6 @@
 import org.eclipse.emf.ecore.resource.Resource;
 import org.eclipse.emf.ecore.util.EcoreUtil;
 import org.eclipse.emf.ecore.xmi.impl.XMIResourceImpl;
-import org.eclipse.syson.sysml.Element;
 import org.eclipse.emf.edit.provider.ComposedAdapterFactory.Descriptor;
 import org.eclipse.sirius.components.collaborative.forms.services.api.IPropertiesDescriptionRegistry;
 import org.eclipse.sirius.components.collaborative.forms.services.api.IPropertiesDescriptionRegistryConfigurer;
@@ -63,8 +62,9 @@
 import org.eclipse.syson.model.services.ModelMutationElementService;
 import org.eclipse.syson.model.services.aql.ModelMutationAQLService;
 import org.eclipse.syson.model.services.aql.ModelQueryAQLService;
-import org.eclipse.syson.services.UtilService;
+import org.eclipse.syson.sysml.Element;
 import org.eclipse.syson.sysml.SysmlPackage;
+import org.eclipse.syson.sysml.metamodel.services.MetamodelQueryElementService;
 import org.eclipse.syson.util.AQLConstants;
 import org.eclipse.syson.util.AQLUtils;
 import org.eclipse.syson.util.ServiceMethod;
@@ -119,10 +119,10 @@ public class SysMLv2PropertiesConfigurer implements IPropertiesDescriptionRegist
 
     private final ILabelService labelService;
 
-    private final UtilService utilService;
-
     private final IReadOnlyObjectPredicate readOnlyObjectPredicate;
 
+    private final MetamodelQueryElementService metamodelQueryElementService;
+
     private final List<IDetailsViewHelpTextProvider> detailViewHelpTextProviders;
 
     public SysMLv2PropertiesConfigurer(List<Descriptor> composedAdapterFactoryDescriptors, ViewFormDescriptionConverter converter, IFeedbackMessageService feedbackMessageService,
@@ -133,7 +133,7 @@ public SysMLv2PropertiesConfigurer(List<Descriptor> composedAdapterFactoryDescri
         this.labelService = Objects.requireNonNull(labelService);
         this.readOnlyObjectPredicate = Objects.requireNonNull(readOnlyObjectPredicate);
         this.detailViewHelpTextProviders = Objects.requireNonNull(detailViewHelpTextProviders);
-        this.utilService = new UtilService();
+        this.metamodelQueryElementService = new MetamodelQueryElementService();
     }
 
     @Override
@@ -155,7 +155,8 @@ public void addPropertiesDescriptions(IPropertiesDescriptionRegistry registry) {
 
         // Convert the View-based FormDescription and register the result into the system
         AQLInterpreter interpreter = new AQLInterpreter(List.of(),
-                List.of(new DetailsViewService(this.composedAdapterFactoryDescriptors, this.feedbackMessageService, this.readOnlyObjectPredicate, this.detailViewHelpTextProviders), this.labelService, this.utilService,
+                List.of(new DetailsViewService(this.composedAdapterFactoryDescriptors, this.feedbackMessageService, this.readOnlyObjectPredicate, this.metamodelQueryElementService,
+                        this.detailViewHelpTextProviders), this.labelService,
                         new ModelMutationAQLService(new ModelMutationElementService()), new ModelQueryAQLService(), new FormMutationAQLService(), new FormQueryAQLService()),
                 List.of(SysmlPackage.eINSTANCE));
         ViewConverterResult converterResult = this.converter.convert(viewFormDescription, List.of(), interpreter);
@@ -188,6 +189,8 @@ private FormDescription createDetailsViewForElement() {
         pageCore.getGroups().add(this.createExtraAcceptActionUsagePropertiesGroup());
         pageCore.getGroups().add(this.createExtraTransitionSourceTargetPropertiesGroup());
         pageCore.getGroups().add(this.createFeatureValuePropertiesGroup());
+        pageCore.getGroups().add(this.createResultExpressionPropertiesGroup());
+        pageCore.getGroups().add(this.createExpressionPropertiesGroup());
 
         PageDescription pageAdvanced = FormFactory.eINSTANCE.createPageDescription();
         pageAdvanced.setName("SysON-DetailsView-Advanced");
@@ -217,7 +220,7 @@ private GroupDescription createFeatureValuePropertiesGroup() {
 
         TextAreaDescription expressionWidget = FormFactory.eINSTANCE.createTextAreaDescription();
         expressionWidget.setName("ValueExpression");
-        expressionWidget.setLabelExpression("Value");
+        expressionWidget.setLabelExpression("custom:Value");
         expressionWidget.setValueExpression(ServiceMethod.of0(DetailsViewService::getValueExpressionTextualRepresentation).aqlSelf());
         expressionWidget.setIsEnabledExpression(AQLConstants.AQL_FALSE);
 
@@ -226,6 +229,52 @@ private GroupDescription createFeatureValuePropertiesGroup() {
         return group;
     }
 
+    /**
+     * Creates a group to display the value of an Expression.
+     *
+     * @return a {@link GroupDescription}
+     */
+    private GroupDescription createExpressionPropertiesGroup() {
+        GroupDescription group = FormFactory.eINSTANCE.createGroupDescription();
+        group.setDisplayMode(GroupDisplayMode.LIST);
+        group.setName("Result");
+        group.setLabelExpression("");
+        group.setSemanticCandidatesExpression(ServiceMethod.of0(DetailsViewService::getExpression).aqlSelf());
+
+        TextAreaDescription expressionWidget = FormFactory.eINSTANCE.createTextAreaDescription();
+        expressionWidget.setName("Expression");
+        expressionWidget.setLabelExpression("custom:Expression");
+        expressionWidget.setValueExpression(ServiceMethod.of0(DetailsViewService::getExpressionTextualRepresentation).aqlSelf());
+        expressionWidget.setIsEnabledExpression(AQLConstants.AQL_FALSE);
+
+        group.getChildren().add(expressionWidget);
+
+        return group;
+    }
+
+    /**
+     * Creates a group to display the value of a ResultExpression.
+     *
+     * @return a {@link GroupDescription}
+     */
+    private GroupDescription createResultExpressionPropertiesGroup() {
+        GroupDescription group = FormFactory.eINSTANCE.createGroupDescription();
+        group.setDisplayMode(GroupDisplayMode.LIST);
+        group.setName("Result");
+        group.setLabelExpression("");
+        group.setSemanticCandidatesExpression(ServiceMethod.of0(DetailsViewService::getResultExpression).aqlSelf());
+
+        TextAreaDescription expressionWidget = FormFactory.eINSTANCE.createTextAreaDescription();
+        expressionWidget.setName("ResultExpression");
+        expressionWidget.setLabelExpression("Result");
+        expressionWidget.setValueExpression(ServiceMethod.of0(DetailsViewService::getResultExpressionTextualRepresentation).aqlSelf());
+        expressionWidget.setIsEnabledExpression(AQLConstants.AQL_FALSE);
+
+        group.getChildren().add(expressionWidget);
+
+        return group;
+    }
+
     private GroupDescription createCorePropertiesGroup() {
         GroupDescription group = FormFactory.eINSTANCE.createGroupDescription();
         group.setDisplayMode(GroupDisplayMode.LIST);

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/expressions/dto/DeleteExpressionInput.java

@@ -0,0 +1,25 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.expressions.dto;
+
+import java.util.UUID;
+
+import org.eclipse.sirius.components.core.api.IInput;
+
+/**
+ * The input object for the {@code deleteExpression} mutation.
+ *
+ * @author pcdavid
+ */
+public record DeleteExpressionInput(UUID id, String editingContextId, String parentElementId) implements IInput {
+}

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/expressions/dto/ExpressionTextualRepresentationInput.java

@@ -0,0 +1,25 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.expressions.dto;
+
+import java.util.UUID;
+
+import org.eclipse.sirius.components.core.api.IInput;
+
+/**
+ * Input for the {@code expressionTextualRepresentation} query field on EditingContext.
+ *
+ * @author pcdavid
+ */
+public record ExpressionTextualRepresentationInput(UUID id, String editingContextId, String elementId) implements IInput {
+}

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/expressions/dto/ExpressionTextualRepresentationPayload.java

@@ -0,0 +1,29 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.expressions.dto;
+
+import java.util.Objects;
+import java.util.UUID;
+
+import org.eclipse.sirius.components.core.api.IPayload;
+
+/**
+ * Payload for the {@code expressionTextualRepresentation} query field on EditingContext.
+ *
+ * @author pcdavid
+ */
+public record ExpressionTextualRepresentationPayload(UUID id, String textualRepresentation) implements IPayload {
+    public ExpressionTextualRepresentationPayload {
+        Objects.requireNonNull(id);
+    }
+}

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/expressions/graphql/EditingContextExpressionTextualRepresentationDataFetcher.java

@@ -0,0 +1,56 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.expressions.graphql;
+
+import java.util.Objects;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+
+import org.eclipse.sirius.components.annotations.spring.graphql.QueryDataFetcher;
+import org.eclipse.sirius.components.graphql.api.IDataFetcherWithFieldCoordinates;
+import org.eclipse.sirius.components.graphql.api.IEditingContextDispatcher;
+import org.eclipse.syson.application.expressions.dto.ExpressionTextualRepresentationInput;
+import org.eclipse.syson.application.expressions.dto.ExpressionTextualRepresentationPayload;
+
+import graphql.schema.DataFetchingEnvironment;
+
+/**
+ * Data fetcher for the field {@code EditingContext#expressionTextualRepresentation} to fetch the textual representation
+ * of a SysMLv2 expression.
+ *
+ * @author pcdavid
+ */
+@QueryDataFetcher(type = "EditingContext", field = "expressionTextualRepresentation")
+public class EditingContextExpressionTextualRepresentationDataFetcher implements IDataFetcherWithFieldCoordinates<CompletableFuture<String>> {
+
+    private static final String ELEMENT_ID_ARGUMENT = "elementId";
+
+    private final IEditingContextDispatcher editingContextDispatcher;
+
+    public EditingContextExpressionTextualRepresentationDataFetcher(IEditingContextDispatcher editingContextDispatcher) {
+        this.editingContextDispatcher = Objects.requireNonNull(editingContextDispatcher);
+    }
+
+    @Override
+    public CompletableFuture<String> get(DataFetchingEnvironment environment) throws Exception {
+        String editingContextId = environment.getSource();
+        String elementId = environment.getArgument(ELEMENT_ID_ARGUMENT);
+
+        ExpressionTextualRepresentationInput input = new ExpressionTextualRepresentationInput(UUID.randomUUID(), editingContextId, elementId);
+        return this.editingContextDispatcher.dispatchQuery(input.editingContextId(), input)
+                .filter(ExpressionTextualRepresentationPayload.class::isInstance)
+                .map(ExpressionTextualRepresentationPayload.class::cast)
+                .map(ExpressionTextualRepresentationPayload::textualRepresentation)
+                .toFuture();
+    }
+}

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/expressions/graphql/MutationDeleteExpressionDataFetcher.java

@@ -0,0 +1,57 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.expressions.graphql;
+
+import java.util.Objects;
+import java.util.concurrent.CompletableFuture;
+
+import org.eclipse.sirius.components.annotations.spring.graphql.MutationDataFetcher;
+import org.eclipse.sirius.components.core.api.IPayload;
+import org.eclipse.sirius.components.graphql.api.IDataFetcherWithFieldCoordinates;
+import org.eclipse.sirius.components.graphql.api.IEditingContextDispatcher;
+import org.eclipse.sirius.components.graphql.api.IExceptionWrapper;
+import org.eclipse.syson.application.expressions.dto.DeleteExpressionInput;
+
+import graphql.schema.DataFetchingEnvironment;
+import tools.jackson.databind.ObjectMapper;
+
+/**
+ * The GraphQL data-fetcher for the {@code deleteExpression} mutation to delete the expression associated to a SysMLv2
+ * element.
+ *
+ * @author pcdavid
+ */
+@MutationDataFetcher(type = "Mutation", field = "deleteExpression")
+public class MutationDeleteExpressionDataFetcher implements IDataFetcherWithFieldCoordinates<CompletableFuture<IPayload>> {
+
+    private static final String INPUT_ARGUMENT = "input";
+
+    private final ObjectMapper objectMapper;
+
+    private final IExceptionWrapper exceptionWrapper;
+
+    private final IEditingContextDispatcher editingContextDispatcher;
+
+    public MutationDeleteExpressionDataFetcher(ObjectMapper objectMapper, IExceptionWrapper exceptionWrapper, IEditingContextDispatcher editingContextDispatcher) {
+        this.objectMapper = Objects.requireNonNull(objectMapper);
+        this.exceptionWrapper = Objects.requireNonNull(exceptionWrapper);
+        this.editingContextDispatcher = Objects.requireNonNull(editingContextDispatcher);
+    }
+
+    @Override
+    public CompletableFuture<IPayload> get(DataFetchingEnvironment environment) throws Exception {
+        Object argument = environment.getArgument(INPUT_ARGUMENT);
+        var input = this.objectMapper.convertValue(argument, DeleteExpressionInput.class);
+        return this.exceptionWrapper.wrapMono(() -> this.editingContextDispatcher.dispatchMutation(input.editingContextId(), input), input).toFuture();
+    }
+}