Implement Go To Implementations command (#1430)

Author: ahejlsberg

internal/ast/ast.go

@@ -605,15 +605,13 @@ func (n *Node) Type() *Node {
 		return n.AsCommonJSExport().Type
 	case KindBinaryExpression:
 		return n.AsBinaryExpression().Type
-	case KindEnumMember, KindBindingElement:
-		return nil
 	default:
 		funcLike := n.FunctionLikeData()
 		if funcLike != nil {
 			return funcLike.Type
 		}
 	}
-	panic("Unhandled case in Node.Type: " + n.Kind.String())
+	return nil
 }
 
 func (n *Node) Initializer() *Node {

internal/ls/definition.go

@@ -119,7 +119,7 @@ func getDeclarationNameForKeyword(node *ast.Node) *ast.Node {
 			if decl := core.FirstOrNil(node.Parent.AsVariableDeclarationList().Declarations.Nodes); decl != nil && decl.Name() != nil {
 				return decl.Name()
 			}
-		} else if node.Parent.Name() != nil && node.Pos() < node.Parent.Name().Pos() {
+		} else if node.Parent.DeclarationData() != nil && node.Parent.Name() != nil && node.Pos() < node.Parent.Name().Pos() {
 			return node.Parent.Name()
 		}
 	}

internal/ls/findallreferences.go

@@ -128,14 +128,10 @@ func newNodeEntryWithKind(node *ast.Node, kind entryKind) *referenceEntry {
 
 func newNodeEntry(node *ast.Node) *referenceEntry {
 	// creates nodeEntry with `kind == entryKindNode`
-	n := node
-	if node != nil && node.Name() != nil {
-		n = node.Name()
-	}
 	return &referenceEntry{
 		kind:    entryKindNode,
-		node:    node,
-		context: getContextNodeForNodeEntry(n),
+		node:    core.OrElse(node.Name(), node),
+		context: getContextNodeForNodeEntry(node),
 	}
 }
 
@@ -410,22 +406,53 @@ func (l *LanguageService) ProvideReferences(params *lsproto.ReferenceParams) []*
 
 	symbolsAndEntries := l.getReferencedSymbolsForNode(position, node, program, program.GetSourceFiles(), options, nil)
 
-	return core.FlatMap(symbolsAndEntries, l.convertSymbolAndEntryToLocation)
+	return core.FlatMap(symbolsAndEntries, l.convertSymbolAndEntriesToLocations)
+}
+
+func (l *LanguageService) ProvideImplementations(params *lsproto.ImplementationParams) []*lsproto.Location {
+	program, sourceFile := l.getProgramAndFile(params.TextDocument.Uri)
+	position := int(l.converters.LineAndCharacterToPosition(sourceFile, params.Position))
+	node := astnav.GetTouchingPropertyName(sourceFile, position)
+
+	var seenNodes collections.Set[*ast.Node]
+	var entries []*referenceEntry
+	queue := l.getImplementationReferenceEntries(program, node, position)
+	for len(queue) != 0 {
+		entry := queue[0]
+		queue = queue[1:]
+		if !seenNodes.Has(entry.node) {
+			seenNodes.Add(entry.node)
+			entries = append(entries, entry)
+			queue = append(queue, l.getImplementationReferenceEntries(program, entry.node, entry.node.Pos())...)
+		}
+	}
+
+	return l.convertEntriesToLocations(entries)
+}
+
+func (l *LanguageService) getImplementationReferenceEntries(program *compiler.Program, node *ast.Node, position int) []*referenceEntry {
+	options := refOptions{use: referenceUseReferences, implementations: true}
+	symbolsAndEntries := l.getReferencedSymbolsForNode(position, node, program, program.GetSourceFiles(), options, nil)
+	return core.FlatMap(symbolsAndEntries, func(s *SymbolAndEntries) []*referenceEntry { return s.references })
 }
 
 // == functions for conversions ==
-func (l *LanguageService) convertSymbolAndEntryToLocation(s *SymbolAndEntries) []*lsproto.Location {
-	var locations []*lsproto.Location
-	for _, ref := range s.references {
-		if ref.textRange == nil {
-			sourceFile := ast.GetSourceFileOfNode(ref.node)
-			ref.textRange = l.getRangeOfNode(ref.node, sourceFile, nil /*endNode*/)
-			ref.fileName = sourceFile.FileName()
+func (l *LanguageService) convertSymbolAndEntriesToLocations(s *SymbolAndEntries) []*lsproto.Location {
+	return l.convertEntriesToLocations(s.references)
+}
+
+func (l *LanguageService) convertEntriesToLocations(entries []*referenceEntry) []*lsproto.Location {
+	locations := make([]*lsproto.Location, len(entries))
+	for i, entry := range entries {
+		if entry.textRange == nil {
+			sourceFile := ast.GetSourceFileOfNode(entry.node)
+			entry.textRange = l.getRangeOfNode(entry.node, sourceFile, nil /*endNode*/)
+			entry.fileName = sourceFile.FileName()
+		}
+		locations[i] = &lsproto.Location{
+			Uri:   FileNameToDocumentURI(entry.fileName),
+			Range: *entry.textRange,
 		}
-		locations = append(locations, &lsproto.Location{
-			Uri:   FileNameToDocumentURI(ref.fileName),
-			Range: *ref.textRange,
-		})
 	}
 	return locations
 }

internal/lsp/server.go

@@ -488,6 +488,8 @@ func (s *Server) handleRequestOrNotification(ctx context.Context, req *lsproto.R
 		return s.handleCompletion(ctx, req)
 	case *lsproto.ReferenceParams:
 		return s.handleReferences(ctx, req)
+	case *lsproto.ImplementationParams:
+		return s.handleImplementations(ctx, req)
 	case *lsproto.SignatureHelpParams:
 		return s.handleSignatureHelp(ctx, req)
 	case *lsproto.DocumentFormattingParams:
@@ -560,6 +562,9 @@ func (s *Server) handleInitialize(req *lsproto.RequestMessage) {
 			ReferencesProvider: &lsproto.BooleanOrReferenceOptions{
 				Boolean: ptrTo(true),
 			},
+			ImplementationProvider: &lsproto.BooleanOrImplementationOptionsOrImplementationRegistrationOptions{
+				Boolean: ptrTo(true),
+			},
 			DiagnosticProvider: &lsproto.DiagnosticOptionsOrDiagnosticRegistrationOptions{
 				DiagnosticOptions: &lsproto.DiagnosticOptions{
 					InterFileDependencies: true,
@@ -725,6 +730,17 @@ func (s *Server) handleReferences(ctx context.Context, req *lsproto.RequestMessa
 	return nil
 }
 
+func (s *Server) handleImplementations(ctx context.Context, req *lsproto.RequestMessage) error {
+	// goToImplementation
+	params := req.Params.(*lsproto.ImplementationParams)
+	project := s.projectService.EnsureDefaultProjectForURI(params.TextDocument.Uri)
+	languageService, done := project.GetLanguageServiceForRequest(ctx)
+	defer done()
+	locations := languageService.ProvideImplementations(params)
+	s.sendResult(req.ID, locations)
+	return nil
+}
+
 func (s *Server) handleCompletion(ctx context.Context, req *lsproto.RequestMessage) error {
 	params := req.Params.(*lsproto.CompletionParams)
 	project := s.projectService.EnsureDefaultProjectForURI(params.TextDocument.Uri)