[1070] Reveal the currently selected representation in the explorer

- Switch to a flat tree format for the GraphQL message so that the
  frontend does not need to keep track of try to guess the depth of
  the tree (and remove the now obsolete maxDpeth).
- Ask the backend to reveal the currently selected elements by
  expanding their ancestors.
- Update TreeRenderer to convert elements to
  reveal (TreeEventInput.revealed) into ancestors to expand using the
  new TreeDescription.getAncestorsProvider().

Bug: #1070
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>

CHANGELOG.adoc

@@ -29,6 +29,8 @@
 - https://github.com/eclipse-sirius/sirius-components/issues/1045[#1045] [core] Providers will now return List<?> instead of List<Object>. This makes it possible for applications to reuse existing services to implement providers without making useless copies of lists
 - https://github.com/eclipse-sirius/sirius-components/issues/1068[#1068] [form] The form representation is now supporting multiple elements as an input
 - https://github.com/eclipse-sirius/sirius-components/issues/1068[#1068] [workbench] The integration of the details view in the workbench is not limited to semantic objects with a kind starting with `siriusComponents://semantic`. Any object can be used as the input of the details view and we will now provide the identifier of all the objects in the selection. This may include graphical elements such as nodes, edges, representations or anything selected in the explorer for example
+- https://github.com/eclipse-sirius/sirius-components/issues/1070[#1070] [tree] `TreeDescription` has a new `getAncestorsProvider()` API used to compute the set of ancestors to expand in a given tree to reveal specified elements.
+- https://github.com/eclipse-sirius/sirius-components/issues/1070[#1070] [tree] The shape of the GraphQL Schema used to send tree instances to the backend has been changed into a flat tree of items (to be rebuilt into a proper tree on the front). This makes the depth of the GraphQL subscription needed to track a particular tree independent on the depth of the tree itself.
 
 === Dependency update
 
@@ -52,6 +54,7 @@
 - https://github.com/eclipse-sirius/sirius-components/issues/1054[#1054] [diagram] Add missing variables to compute the label of an edge
 - https://github.com/eclipse-sirius/sirius-components/issues/1063[#1063] [explorer] It is now possible to expand or collapse items in the explorer without selecting them by clicking directly on the expand/collapse arrow icon
 - https://github.com/eclipse-sirius/sirius-components/issues/1068[#1068] [form] Add support for displaying details on arbitrary element kinds
+- https://github.com/eclipse-sirius/sirius-components/issues/1070[#1070] [explorer] When selecting a specific representation (for example from its URL or from the onboard area), it is automatically made visible and selected in the explorer.
 
 === New features
 

backend/sirius-components-collaborative-trees/src/main/java/org/eclipse/sirius/components/collaborative/trees/TreeEventProcessorFactory.java

@@ -77,6 +77,7 @@ public <T extends IRepresentationEventProcessor> Optional<T> createRepresentatio
                 TreeCreationParameters treeCreationParameters = TreeCreationParameters.newTreeCreationParameters(treeConfiguration.getId())
                         .treeDescription(treeDescription)
                         .expanded(treeConfiguration.getExpanded())
+                        .revealed(treeConfiguration.getRevealed())
                         .editingContext(editingContext)
                         .build();
                 // @formatter:on

backend/sirius-components-collaborative-trees/src/main/java/org/eclipse/sirius/components/collaborative/trees/TreeService.java

@@ -35,6 +35,7 @@ public Tree create(TreeCreationParameters treeCreationParameters) {
         variableManager.put(GetOrCreateRandomIdProvider.PREVIOUS_REPRESENTATION_ID, treeCreationParameters.getId());
         variableManager.put(IEditingContext.EDITING_CONTEXT, treeCreationParameters.getEditingContext());
         variableManager.put(TreeRenderer.EXPANDED, treeCreationParameters.getExpanded());
+        variableManager.put(TreeRenderer.REVEALED, treeCreationParameters.getRevealed());
 
         TreeRenderer treeRenderer = new TreeRenderer(variableManager, treeCreationParameters.getTreeDescription());
         return treeRenderer.render();

backend/sirius-components-collaborative-trees/src/main/java/org/eclipse/sirius/components/collaborative/trees/api/TreeConfiguration.java

@@ -29,10 +29,18 @@ public class TreeConfiguration implements IRepresentationConfiguration {
 
     private final List<String> expanded;
 
+    private List<String> revealed;
+
     public TreeConfiguration(String editingContextId, List<String> expanded) {
-        String uniqueId = editingContextId + expanded.toString();
+        this(editingContextId, expanded, List.of());
+
+    }
+
+    public TreeConfiguration(String editingContextId, List<String> expanded, List<String> revealed) {
+        String uniqueId = editingContextId + expanded.toString() + revealed.toString();
         this.treeId = UUID.nameUUIDFromBytes(uniqueId.getBytes()).toString();
         this.expanded = Objects.requireNonNull(expanded);
+        this.revealed = List.copyOf(Objects.requireNonNull(revealed));
     }
 
     @Override
@@ -44,4 +52,7 @@ public List<String> getExpanded() {
         return this.expanded;
     }
 
+    public List<String> getRevealed() {
+        return this.revealed;
+    }
 }

backend/sirius-components-collaborative-trees/src/main/java/org/eclipse/sirius/components/collaborative/trees/api/TreeCreationParameters.java

@@ -33,6 +33,8 @@ public final class TreeCreationParameters {
 
     private List<String> expanded;
 
+    private List<String> revealed;
+
     private IEditingContext editingContext;
 
     private TreeCreationParameters() {
@@ -51,6 +53,10 @@ public List<String> getExpanded() {
         return this.expanded;
     }
 
+    public List<String> getRevealed() {
+        return this.revealed;
+    }
+
     public IEditingContext getEditingContext() {
         return this.editingContext;
     }
@@ -61,8 +67,8 @@ public static Builder newTreeCreationParameters(String id) {
 
     @Override
     public String toString() {
-        String pattern = "{0} '{'id: {1}, treeDescriptionId: {2}, expanded: {3}'}'"; //$NON-NLS-1$
-        return MessageFormat.format(pattern, this.getClass().getSimpleName(), this.id, this.treeDescription.getId(), this.expanded);
+        String pattern = "{0} '{'id: {1}, treeDescriptionId: {2}, expanded: {3}, revealed: {4}'}'"; //$NON-NLS-1$
+        return MessageFormat.format(pattern, this.getClass().getSimpleName(), this.id, this.treeDescription.getId(), this.expanded, this.revealed);
     }
 
     /**
@@ -78,6 +84,8 @@ public static final class Builder {
 
         private List<String> expanded;
 
+        private List<String> revealed;
+
         private IEditingContext editingContext;
 
         private Builder(String id) {
@@ -94,6 +102,11 @@ public Builder expanded(List<String> expanded) {
             return this;
         }
 
+        public Builder revealed(List<String> revealed) {
+            this.revealed = Objects.requireNonNull(revealed);
+            return this;
+        }
+
         public Builder editingContext(IEditingContext editingContext) {
             this.editingContext = Objects.requireNonNull(editingContext);
             return this;
@@ -104,6 +117,7 @@ public TreeCreationParameters build() {
             treeCreationParameters.id = Objects.requireNonNull(this.id);
             treeCreationParameters.treeDescription = Objects.requireNonNull(this.treeDescription);
             treeCreationParameters.expanded = Objects.requireNonNull(this.expanded);
+            treeCreationParameters.revealed = Objects.requireNonNull(this.revealed);
             treeCreationParameters.editingContext = Objects.requireNonNull(this.editingContext);
             return treeCreationParameters;
         }

backend/sirius-components-collaborative-trees/src/main/java/org/eclipse/sirius/components/collaborative/trees/dto/TreeEventInput.java

@@ -31,14 +31,17 @@ public final class TreeEventInput implements IInput {
 
     private List<String> expanded;
 
+    private List<String> revealed;
+
     public TreeEventInput() {
         // Used by Jackson
     }
 
-    public TreeEventInput(UUID id, String editingContextId, List<String> expanded) {
+    public TreeEventInput(UUID id, String editingContextId, List<String> expanded, List<String> revealed) {
         this.id = Objects.requireNonNull(id);
         this.editingContextId = Objects.requireNonNull(editingContextId);
-        this.expanded = Objects.requireNonNull(expanded);
+        this.expanded = List.copyOf(Objects.requireNonNull(expanded));
+        this.revealed = List.copyOf(Objects.requireNonNull(revealed));
     }
 
     @Override
@@ -54,9 +57,13 @@ public List<String> getExpanded() {
         return this.expanded;
     }
 
+    public List<String> getRevealed() {
+        return this.revealed;
+    }
+
     @Override
     public String toString() {
-        String pattern = "{0} '{'id: {1}, editingContextId: {2}, expanded: {3}'}'"; //$NON-NLS-1$
-        return MessageFormat.format(pattern, this.getClass().getSimpleName(), this.id, this.editingContextId, this.expanded);
+        String pattern = "{0} '{'id: {1}, editingContextId: {2}, expanded: {3}, revealed: {4}'}'"; //$NON-NLS-1$
+        return MessageFormat.format(pattern, this.getClass().getSimpleName(), this.id, this.editingContextId, this.expanded, this.revealed);
     }
 }

backend/sirius-components-collaborative-trees/src/main/resources/schema/tree.graphqls

@@ -6,6 +6,7 @@ input TreeEventInput {
   id: ID!
   editingContextId: ID!
   expanded: [String!]!
+  revealed: [String!]!
 }
 
 union TreeEventPayload = ErrorPayload | SubscribersUpdatedEventPayload | TreeRefreshedEventPayload
@@ -18,19 +19,20 @@ type TreeRefreshedEventPayload {
 type Tree implements Representation {
   id: ID!
   metadata: RepresentationMetadata!
-  children: [TreeItem!]!
+  items: [TreeItem!]!
 }
 
 type TreeItem {
   id: ID!
+  parentId: ID
+  position: Int
   label: String!
   kind: String!
   imageURL: String!
   editable: Boolean!
   deletable: Boolean!
   expanded: Boolean!
   hasChildren: Boolean!
-  children: [TreeItem]!
 }
 
 type TreeDescription implements RepresentationDescription {

backend/sirius-components-trees/src/main/java/org/eclipse/sirius/components/trees/description/TreeDescription.java

@@ -55,6 +55,8 @@ public final class TreeDescription implements IRepresentationDescription {
 
     private Function<VariableManager, List<?>> childrenProvider;
 
+    private Function<VariableManager, List<String>> ancestorsProvider;
+
     private Function<VariableManager, Boolean> hasChildrenProvider;
 
     private Predicate<VariableManager> canCreatePredicate;
@@ -115,6 +117,10 @@ public Function<VariableManager, List<?>> getChildrenProvider() {
         return this.childrenProvider;
     }
 
+    public Function<VariableManager, List<String>> getAncestorsProvider() {
+        return this.ancestorsProvider;
+    }
+
     public Function<VariableManager, Boolean> getHasChildrenProvider() {
         return this.hasChildrenProvider;
     }
@@ -171,6 +177,8 @@ public static final class Builder {
 
         private Function<VariableManager, List<?>> childrenProvider;
 
+        private Function<VariableManager, List<String>> ancestorsProvider = variableManager -> List.of();
+
         private Function<VariableManager, Boolean> hasChildrenProvider;
 
         private Predicate<VariableManager> canCreatePredicate;
@@ -233,6 +241,11 @@ public Builder childrenProvider(Function<VariableManager, List<?>> childrenProvi
             return this;
         }
 
+        public Builder ancestorsProvider(Function<VariableManager, List<String>> ancestorsProvider) {
+            this.ancestorsProvider = Objects.requireNonNull(ancestorsProvider);
+            return this;
+        }
+
         public Builder hasChildrenProvider(Function<VariableManager, Boolean> hasChildrenProvider) {
             this.hasChildrenProvider = Objects.requireNonNull(hasChildrenProvider);
             return this;
@@ -266,6 +279,7 @@ public TreeDescription build() {
             treeDescription.deletableProvider = Objects.requireNonNull(this.deletableProvider);
             treeDescription.elementsProvider = Objects.requireNonNull(this.elementsProvider);
             treeDescription.childrenProvider = Objects.requireNonNull(this.childrenProvider);
+            treeDescription.ancestorsProvider = Objects.requireNonNull(this.ancestorsProvider);
             treeDescription.hasChildrenProvider = Objects.requireNonNull(this.hasChildrenProvider);
             treeDescription.canCreatePredicate = Objects.requireNonNull(this.canCreatePredicate);
             treeDescription.deleteHandler = Objects.requireNonNull(this.deleteHandler);

backend/sirius-components-trees/src/main/java/org/eclipse/sirius/components/trees/renderer/TreeRenderer.java

@@ -15,6 +15,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.eclipse.sirius.components.representations.VariableManager;
 import org.eclipse.sirius.components.trees.Tree;
@@ -30,9 +31,11 @@ public class TreeRenderer {
 
     public static final String EXPANDED = "expanded"; //$NON-NLS-1$
 
-    private VariableManager variableManager;
+    public static final String REVEALED = "revealed"; //$NON-NLS-1$
 
-    private TreeDescription treeDescription;
+    private final VariableManager variableManager;
+
+    private final TreeDescription treeDescription;
 
     public TreeRenderer(VariableManager variableManager, TreeDescription treeDescription) {
         this.variableManager = Objects.requireNonNull(variableManager);
@@ -43,6 +46,12 @@ public Tree render() {
         String treeId = this.treeDescription.getIdProvider().apply(this.variableManager);
         String label = this.treeDescription.getLabelProvider().apply(this.variableManager);
 
+        List<String> expandedIds = new ArrayList<>();
+        expandedIds.addAll(this.getExpandedIds());
+        List<String> ancestors = this.treeDescription.getAncestorsProvider().apply(this.variableManager);
+        expandedIds.addAll(ancestors);
+        this.variableManager.put(TreeRenderer.EXPANDED, List.copyOf(expandedIds));
+
         List<?> rootElements = this.treeDescription.getElementsProvider().apply(this.variableManager);
         List<TreeItem> childrenItems = new ArrayList<>(rootElements.size());
         for (Object rootElement : rootElements) {
@@ -60,6 +69,16 @@ public Tree render() {
         // @formatter:on
     }
 
+    private List<String> getExpandedIds() {
+        List<String> expandedIds = new ArrayList<>();
+        Object objects = this.variableManager.getVariables().get(TreeRenderer.EXPANDED);
+        if (objects instanceof List<?>) {
+            List<?> list = (List<?>) objects;
+            expandedIds = list.stream().filter(String.class::isInstance).map(String.class::cast).collect(Collectors.toUnmodifiableList());
+        }
+        return expandedIds;
+    }
+
     private TreeItem renderTreeItem(VariableManager treeItemVariableManager) {
         String id = this.treeDescription.getTreeItemIdProvider().apply(treeItemVariableManager);
         String kind = this.treeDescription.getKindProvider().apply(treeItemVariableManager);

frontend/src/explorer/ExplorerWebSocketContainer.tsx

@@ -10,7 +10,7 @@
  * Contributors:
  *     Obeo - initial API and implementation
  *******************************************************************************/
-import { gql, useSubscription } from '@apollo/client';
+import { useSubscription } from '@apollo/client';
 import { M, Spacing } from 'core/spacing/Spacing';
 import { Text } from 'core/text/Text';
 import {
@@ -20,30 +20,63 @@ import {
   HANDLE_DATA__ACTION,
   HANDLE_ERROR__ACTION,
   HANDLE_EXPANDED__ACTION,
+  HANDLE_SYNCHRONIZE__ACTION,
   LOADING__STATE,
 } from 'explorer/machine';
-import React, { useReducer } from 'react';
+import gql from 'graphql-tag';
+import React, { useEffect, useReducer } from 'react';
 import { Explorer } from './Explorer';
 import styles from './ExplorerWebSocketContainer.module.css';
 import { ExplorerWebSocketContainerProps } from './ExplorerWebSocketContainer.types';
-import { getTreeEventSubscription } from './getTreeEventSubscription';
 import { initialState, reducer } from './reducer';
 
+const treeEventSubscription = gql`
+  subscription treeEvent($input: TreeEventInput!) {
+    treeEvent(input: $input) {
+      __typename
+      ... on TreeRefreshedEventPayload {
+        id
+        tree {
+          id
+          items {
+            id
+            parentId
+            position
+            hasChildren
+            expanded
+            label
+            editable
+            deletable
+            kind
+            imageURL
+          }
+        }
+      }
+    }
+  }
+`;
+
 export const ExplorerWebSocketContainer = ({
   editingContextId,
   selection,
   setSelection,
   readOnly,
 }: ExplorerWebSocketContainerProps) => {
   const [state, dispatch] = useReducer(reducer, initialState);
-  const { viewState, id, tree, expanded, maxDepth, message } = state;
+  const { viewState, id, tree, expanded, synchronized, message } = state;
 
-  const { error } = useSubscription(gql(getTreeEventSubscription(maxDepth)), {
+  let revealed = [];
+  if (synchronized && selection.entries.length > 0) {
+    revealed = selection.entries.map((entry) => entry.kind + '&id=' + entry.id);
+  }
+
+  const { error } = useSubscription(treeEventSubscription, {
     variables: {
       input: {
         id,
         editingContextId,
         expanded,
+        revealed,
       },
     },
     fetchPolicy: 'no-cache',
@@ -57,6 +90,11 @@ export const ExplorerWebSocketContainer = ({
     dispatch({ type: HANDLE_ERROR__ACTION, message: error });
   }
 
+  // Enable synchronize mode when the selection is explicitly changed
+  useEffect(() => {
+    dispatch({ type: HANDLE_SYNCHRONIZE__ACTION, synchronized: true });
+  }, [selection]);
+
   const onExpand = (id: string, depth: number) => {
     dispatch({ type: HANDLE_EXPANDED__ACTION, id, depth });
   };