fix(language): hide current implicit proposal

Content assist proposals should not display the object that is only
added to the model because the current context assist input refers to
it (e.g., an implicit node or variable that is only referenced in the
currently edited context).

2 files changed, 86 insertions, 1 deletions

diff --git a/language-ide/src/main/java/tools/refinery/language/ide/ProblemIdeModule.java b/language-ide/src/main/java/tools/refinery/language/ide/ProblemIdeModule.java
index 3502c29f..51cecf06 100644
--- a/language-ide/src/main/java/tools/refinery/language/ide/ProblemIdeModule.java
+++ b/language-ide/src/main/java/tools/refinery/language/ide/ProblemIdeModule.java
@@ -4,9 +4,11 @@
 package tools.refinery.language.ide;
 
 import org.eclipse.xtext.ide.editor.contentassist.IPrefixMatcher;
+import org.eclipse.xtext.ide.editor.contentassist.IdeCrossrefProposalProvider;
 import org.eclipse.xtext.ide.editor.syntaxcoloring.ISemanticHighlightingCalculator;
 
 import tools.refinery.language.ide.contentassist.FuzzyMatcher;
+import tools.refinery.language.ide.contentassist.ProblemCrossrefProposalProvider;
 import tools.refinery.language.ide.syntaxcoloring.ProblemSemanticHighlightingCalculator;
 
 /**
@@ -16,9 +18,13 @@ public class ProblemIdeModule extends AbstractProblemIdeModule {
         public Class<? extends ISemanticHighlightingCalculator> bindISemanticHighlightingCalculator() {
                 return ProblemSemanticHighlightingCalculator.class;
         }
-        
+
         @Override
         public Class<? extends IPrefixMatcher> bindIPrefixMatcher() {
                 return FuzzyMatcher.class;
         }
+
+        public Class<? extends IdeCrossrefProposalProvider> bindIdeCrossrefProposalProvider() {
+                return ProblemCrossrefProposalProvider.class;
+        }
 }
diff --git a/language-ide/src/main/java/tools/refinery/language/ide/contentassist/ProblemCrossrefProposalProvider.java b/language-ide/src/main/java/tools/refinery/language/ide/contentassist/ProblemCrossrefProposalProvider.java
new file mode 100644
index 00000000..416535ce
--- /dev/null
+++ b/language-ide/src/main/java/tools/refinery/language/ide/contentassist/ProblemCrossrefProposalProvider.java
@@ -0,0 +1,79 @@
+package tools.refinery.language.ide.contentassist;
+
+import java.util.Objects;
+
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.util.EcoreUtil;
+import org.eclipse.xtext.CrossReference;
+import org.eclipse.xtext.GrammarUtil;
+import org.eclipse.xtext.ide.editor.contentassist.ContentAssistContext;
+import org.eclipse.xtext.ide.editor.contentassist.ContentAssistEntry;
+import org.eclipse.xtext.ide.editor.contentassist.IdeCrossrefProposalProvider;
+import org.eclipse.xtext.nodemodel.util.NodeModelUtils;
+import org.eclipse.xtext.resource.IEObjectDescription;
+
+import com.google.inject.Inject;
+
+import tools.refinery.language.model.ProblemUtil;
+import tools.refinery.language.model.problem.Problem;
+import tools.refinery.language.resource.ReferenceCounter;
+
+public class ProblemCrossrefProposalProvider extends IdeCrossrefProposalProvider {
+        @Inject
+        private ReferenceCounter referenceCounter;
+
+        @Override
+        protected ContentAssistEntry createProposal(IEObjectDescription candidate, CrossReference crossRef,
+                        ContentAssistContext context) {
+                if (!shouldCreateProposal(candidate, crossRef, context)) {
+                        return null;
+                }
+                return super.createProposal(candidate, crossRef, context);
+        }
+
+        protected boolean shouldCreateProposal(IEObjectDescription candidate, CrossReference crossRef,
+                        ContentAssistContext context) {
+                var rootModel = context.getRootModel();
+                var eObjectOrProxy = candidate.getEObjectOrProxy();
+                if (!Objects.equals(rootModel.eResource(), eObjectOrProxy.eResource())) {
+                        return true;
+                }
+                var currentValue = getCurrentValue(crossRef, context);
+                if (currentValue == null) {
+                        return true;
+                }
+                var eObject = EcoreUtil.resolve(eObjectOrProxy, rootModel);
+                if (!Objects.equals(currentValue, eObject)) {
+                        return true;
+                }
+                if (!ProblemUtil.isImplicit(eObject)) {
+                        return true;
+                }
+                if (rootModel instanceof Problem problem) {
+                        var referenceCounts = referenceCounter.getReferenceCounts(problem);
+                        var count = referenceCounts.get(eObject);
+                        return count != null && count >= 2;
+                }
+                return true;
+        }
+
+        protected EObject getCurrentValue(CrossReference crossRef, ContentAssistContext context) {
+                var value = getCurrentValue(crossRef, context.getCurrentModel());
+                if (value != null) {
+                        return value;
+                }
+                var currentNodeSemanticObject = NodeModelUtils.findActualSemanticObjectFor(context.getCurrentNode());
+                return getCurrentValue(crossRef, currentNodeSemanticObject);
+        }
+
+        protected EObject getCurrentValue(CrossReference crossRef, EObject context) {
+                if (context == null) {
+                        return null;
+                }
+                var eReference = GrammarUtil.getReference(crossRef, context.eClass());
+                if (eReference == null || eReference.isMany()) {
+                        return null;
+                }
+                return (EObject) context.eGet(eReference);
+        }
+}