Simplify index signature generation

Author: Arthur Ozga

src/compiler/checker.ts

@@ -2037,7 +2037,7 @@ namespace ts {
             return result;
         }
 
-        function indexSignatureToString(info: IndexInfo, kind: SyntaxKind, enclosingDeclaration?: Node): string {
+        function indexSignatureToString(info: IndexInfo, kind: IndexKind, enclosingDeclaration?: Node): string {
             const writer = getSingleLineStringWriter();
             getSymbolDisplayBuilder().buildIndexSignatureDisplay(info, writer, kind, enclosingDeclaration);
             const result = writer.string();
@@ -2557,8 +2557,8 @@ namespace ts {
                         writePunctuation(writer, SyntaxKind.SemicolonToken);
                         writer.writeLine();
                     }
-                    buildIndexSignatureDisplay(resolved.stringIndexInfo, writer, SyntaxKind.StringKeyword, enclosingDeclaration, globalFlags, symbolStack);
-                    buildIndexSignatureDisplay(resolved.numberIndexInfo, writer, SyntaxKind.NumberKeyword, enclosingDeclaration, globalFlags, symbolStack);
+                    buildIndexSignatureDisplay(resolved.stringIndexInfo, writer, IndexKind.String, enclosingDeclaration, globalFlags, symbolStack);
+                    buildIndexSignatureDisplay(resolved.numberIndexInfo, writer, IndexKind.Number, enclosingDeclaration, globalFlags, symbolStack);
                     for (const p of resolved.properties) {
                         const t = getTypeOfSymbol(p);
                         if (p.flags & (SymbolFlags.Function | SymbolFlags.Method) && !getPropertiesOfObjectType(t).length) {
@@ -2791,10 +2791,7 @@ namespace ts {
                 buildReturnTypeDisplay(signature, writer, enclosingDeclaration, flags, symbolStack);
             }
 
-            /**
-             * @param keyword The keyword for the type of IndexSignature. Must be one of SyntaxKind.NumberKeyword or SyntaxKind.StringKeyword.
-             */
-            function buildIndexSignatureDisplay(info: IndexInfo, writer: SymbolWriter, keyword: SyntaxKind, enclosingDeclaration?: Node, globalFlags?: TypeFormatFlags, symbolStack?: Symbol[]) {
+            function buildIndexSignatureDisplay(info: IndexInfo, writer: SymbolWriter, kind: IndexKind, enclosingDeclaration?: Node, globalFlags?: TypeFormatFlags, symbolStack?: Symbol[]) {
                 if (info) {
                     if (info.isReadonly) {
                         writeKeyword(writer, SyntaxKind.ReadonlyKeyword);
@@ -2804,7 +2801,15 @@ namespace ts {
                     writer.writeParameter(info.declaration ? declarationNameToString(info.declaration.parameters[0].name) : "x");
                     writePunctuation(writer, SyntaxKind.ColonToken);
                     writeSpace(writer);
-                    writeKeyword(writer, keyword);
+                    switch (kind) {
+                        case IndexKind.Number:
+                            writeKeyword(writer, SyntaxKind.NumberKeyword);
+                            break;
+                        case IndexKind.String:
+                            writeKeyword(writer, SyntaxKind.StringKeyword);
+                            break;
+                    }
+
                     writePunctuation(writer, SyntaxKind.CloseBracketToken);
                     writePunctuation(writer, SyntaxKind.ColonToken);
                     writeSpace(writer);

src/compiler/types.ts

@@ -2353,7 +2353,7 @@ namespace ts {
         getTypeAtLocation(node: Node): Type;
         getTypeFromTypeReference(node: TypeReferenceNode | ExpressionWithTypeArguments | JSDocTypeReference): Type;
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;
-        indexSignatureToString(info: IndexInfo, kind: SyntaxKind, enclosingDeclaration?: Node): string;
+        indexSignatureToString(info: IndexInfo, kind: IndexKind, enclosingDeclaration?: Node): string;
         typeToString(type: Type, enclosingDeclaration?: Node, flags?: TypeFormatFlags): string;
         symbolToString(symbol: Symbol, enclosingDeclaration?: Node, meaning?: SymbolFlags): string;
         createSymbol(flags: SymbolFlags, name: string): Symbol;
@@ -2398,7 +2398,7 @@ namespace ts {
         buildTypeDisplay(type: Type, writer: SymbolWriter, enclosingDeclaration?: Node, flags?: TypeFormatFlags): void;
         buildSymbolDisplay(symbol: Symbol, writer: SymbolWriter, enclosingDeclaration?: Node, meaning?: SymbolFlags, flags?: SymbolFormatFlags): void;
         buildSignatureDisplay(signatures: Signature, writer: SymbolWriter, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): void;
-        buildIndexSignatureDisplay(info: IndexInfo, writer: SymbolWriter, keyword: SyntaxKind, enclosingDeclaration?: Node, globalFlags?: TypeFormatFlags, symbolStack?: Symbol[]): void;
+        buildIndexSignatureDisplay(info: IndexInfo, writer: SymbolWriter, kind: IndexKind, enclosingDeclaration?: Node, globalFlags?: TypeFormatFlags, symbolStack?: Symbol[]): void;
         buildParameterDisplay(parameter: Symbol, writer: SymbolWriter, enclosingDeclaration?: Node, flags?: TypeFormatFlags): void;
         buildTypeParameterDisplay(tp: TypeParameter, writer: SymbolWriter, enclosingDeclaration?: Node, flags?: TypeFormatFlags): void;
         buildTypePredicateDisplay(predicate: TypePredicate, writer: SymbolWriter, enclosingDeclaration?: Node, flags?: TypeFormatFlags): void;

src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts

@@ -22,29 +22,16 @@ namespace ts.codefix {
             const hasStringIndexSignature = !!checker.getIndexTypeOfType(classType, IndexKind.String);
 
             for (const implementedTypeNode of implementedTypeNodes) {
-                const implementedType = checker.getTypeFromTypeReference(implementedTypeNode) as InterfaceTypeWithDeclaredMembers;
+                const implementedType = checker.getTypeFromTypeReference(implementedTypeNode) as InterfaceType;
                 // Note that this is ultimately derived from a map indexed by symbol names,
                 // so duplicates cannot occur.
                 const implementedTypeSymbols = checker.getPropertiesOfType(implementedType);
                 const nonPrivateMembers = implementedTypeSymbols.filter(symbolRefersToNonPrivateMember);
 
-                let insertion = "";
-
-                if (!hasNumericIndexSignature) {
-                    const typeNumericIndexInfo = checker.getIndexInfoOfType(implementedType, IndexKind.Number);
-                    if (typeNumericIndexInfo) {
-                        insertion = checker.indexSignatureToString(typeNumericIndexInfo, SyntaxKind.NumberKeyword, classDecl);
-                    }
-                }
-
-                if (!hasStringIndexSignature) {
-                    const typeStringIndexInfo = checker.getIndexInfoOfType(implementedType, IndexKind.String);
-                    if (typeStringIndexInfo) {
-                        insertion += checker.indexSignatureToString(typeStringIndexInfo, SyntaxKind.StringKeyword, classDecl);
-                    }
-                }
-
+                let insertion = getMissingIndexSignatureInsertion(implementedType, IndexKind.Number, classDecl, hasNumericIndexSignature);
+                insertion += getMissingIndexSignatureInsertion(implementedType, IndexKind.String, classDecl, hasStringIndexSignature);
                 insertion += getMissingMembersInsertion(classDecl, nonPrivateMembers, checker, context.newLineCharacter);
+
                 const message = formatStringFromArgs(getLocaleSpecificMessage(Diagnostics.Implement_interface_0), [implementedTypeNode.getText()]);
                 if (insertion) {
                     pushAction(result, insertion, message);
@@ -53,6 +40,16 @@ namespace ts.codefix {
 
             return result;
 
+            function getMissingIndexSignatureInsertion(type: InterfaceType, kind: IndexKind, enclosingDeclaration: ClassLikeDeclaration, hasIndexSigOfKind: boolean) {
+                if (!hasIndexSigOfKind) {
+                    const IndexInfoOfKind = checker.getIndexInfoOfType(type, kind);
+                    if (IndexInfoOfKind) {
+                        return checker.indexSignatureToString(IndexInfoOfKind, kind, enclosingDeclaration);
+                    }
+                }
+                return "";
+            }
+
             function symbolRefersToNonPrivateMember(symbol: Symbol): boolean {
                 const decls = symbol.getDeclarations();
                 Debug.assert(!!(decls && decls.length > 0));