Add refactor to convert namespace to named imports and back

src/compiler/diagnosticMessages.json

@@ -4289,5 +4289,13 @@
     "Convert '{0}' to mapped object type": {
         "category": "Message",
         "code": 95055
+    },
+    "Convert namespace import to named imports": {
+        "category": "Message",
+        "code": 95056
+    },
+    "Convert named imports to namespace import": {
+        "category": "Message",
+        "code": 95057
     }
 }

src/compiler/utilities.ts

@@ -223,11 +223,11 @@ namespace ts {
     }
 
     /**
-     * Returns a value indicating whether a name is unique globally or within the current file
+     * Returns a value indicating whether a name is unique globally or within the current file.
+     * Note: This does not consider whether a name appears as a free identifier or not. For that, use `forEachFreeIdentifier`.
      */
-    export function isFileLevelUniqueName(currentSourceFile: SourceFile, name: string, hasGlobalName?: PrintHandlers["hasGlobalName"]): boolean {
-        return !(hasGlobalName && hasGlobalName(name))
-            && !currentSourceFile.identifiers.has(name);
+    export function isFileLevelUniqueName(sourceFile: SourceFile, name: string, hasGlobalName?: PrintHandlers["hasGlobalName"]): boolean {
+        return !(hasGlobalName && hasGlobalName(name)) && !sourceFile.identifiers.has(name);
     }
 
     // Returns true if this node is missing from the actual source code. A 'missing' node is different

src/harness/tsconfig.json

@@ -120,6 +120,7 @@
         "../services/codefixes/useDefaultImport.ts",
         "../services/codefixes/fixAddModuleReferTypeMissingTypeof.ts",
         "../services/codefixes/convertToMappedObjectType.ts",
+        "../services/refactors/convertImport.ts",
         "../services/refactors/extractSymbol.ts",
         "../services/refactors/generateGetAccessorAndSetAccessor.ts",
         "../services/refactors/moveToNewFile.ts",

src/server/tsconfig.json

@@ -116,6 +116,7 @@
         "../services/codefixes/useDefaultImport.ts",
         "../services/codefixes/fixAddModuleReferTypeMissingTypeof.ts",
         "../services/codefixes/convertToMappedObjectType.ts",
+        "../services/refactors/convertImport.ts",
         "../services/refactors/extractSymbol.ts",
         "../services/refactors/generateGetAccessorAndSetAccessor.ts",
         "../services/refactors/moveToNewFile.ts",

src/server/tsconfig.library.json

@@ -122,6 +122,7 @@
         "../services/codefixes/useDefaultImport.ts",
         "../services/codefixes/fixAddModuleReferTypeMissingTypeof.ts",
         "../services/codefixes/convertToMappedObjectType.ts",
+        "../services/refactors/convertImport.ts",
         "../services/refactors/extractSymbol.ts",
         "../services/refactors/generateGetAccessorAndSetAccessor.ts",
         "../services/refactors/moveToNewFile.ts",

src/services/codefixes/convertToEs6Module.ts

@@ -437,27 +437,10 @@ namespace ts.codefix {
     type FreeIdentifiers = ReadonlyMap<ReadonlyArray<Identifier>>;
     function collectFreeIdentifiers(file: SourceFile): FreeIdentifiers {
         const map = createMultiMap<Identifier>();
-        file.forEachChild(function recur(node) {
-            if (isIdentifier(node) && isFreeIdentifier(node)) {
-                map.add(node.text, node);
-            }
-            node.forEachChild(recur);
-        });
+        forEachFreeIdentifier(file, id => map.add(id.text, id));
         return map;
     }
 
-    function isFreeIdentifier(node: Identifier): boolean {
-        const { parent } = node;
-        switch (parent.kind) {
-            case SyntaxKind.PropertyAccessExpression:
-                return (parent as PropertyAccessExpression).name !== node;
-            case SyntaxKind.BindingElement:
-                return (parent as BindingElement).propertyName !== node;
-            default:
-                return true;
-        }
-    }
-
     // Node helpers
 
     function functionExpressionToDeclaration(name: string | undefined, additionalModifiers: ReadonlyArray<Modifier>, fn: FunctionExpression | ArrowFunction | MethodDeclaration): FunctionDeclaration {

src/services/findAllReferences.ts

@@ -712,16 +712,23 @@ namespace ts.FindAllReferences.Core {
     }
 
     /** Used as a quick check for whether a symbol is used at all in a file (besides its definition). */
-    export function isSymbolReferencedInFile(definition: Identifier, checker: TypeChecker, sourceFile: SourceFile) {
+    export function isSymbolReferencedInFile(definition: Identifier, checker: TypeChecker, sourceFile: SourceFile): boolean {
+        return eachSymbolReferenceInFile(definition, checker, sourceFile, () => true) || false;
+    }
+
+    export function eachSymbolReferenceInFile<T>(definition: Identifier, checker: TypeChecker, sourceFile: SourceFile, cb: (token: Identifier) => T): T | undefined {
         const symbol = checker.getSymbolAtLocation(definition);
-        if (!symbol) return true; // Be lenient with invalid code.
-        return getPossibleSymbolReferenceNodes(sourceFile, symbol.name).some(token => {
-            if (!isIdentifier(token) || token === definition || token.escapedText !== definition.escapedText) return false;
-            const referenceSymbol = checker.getSymbolAtLocation(token)!;
-            return referenceSymbol === symbol
+        if (!symbol) return undefined;
+        for (const token of getPossibleSymbolReferenceNodes(sourceFile, symbol.name)) {
+            if (!isIdentifier(token) || token === definition || token.escapedText !== definition.escapedText) continue;
+            const referenceSymbol: Symbol = checker.getSymbolAtLocation(token)!; // See GH#19955 for why the type annotation is necessary
+            if (referenceSymbol === symbol
                 || checker.getShorthandAssignmentValueSymbol(token.parent) === symbol
-                || isExportSpecifier(token.parent) && getLocalSymbolForExportSpecifier(token, referenceSymbol, token.parent, checker) === symbol;
-        });
+                || isExportSpecifier(token.parent) && getLocalSymbolForExportSpecifier(token, referenceSymbol, token.parent, checker) === symbol) {
+                const res = cb(token);
+                if (res) return res;
+            }
+        }
     }
 
     function getPossibleSymbolReferenceNodes(sourceFile: SourceFile, symbolName: string, container: Node = sourceFile): ReadonlyArray<Node> {

src/services/refactors/convertImport.ts

@@ -0,0 +1,104 @@
+/* @internal */
+namespace ts.refactor.generateGetAccessorAndSetAccessor {
+    const refactorName = "Convert import";
+    const actionNameNamespaceToNamed = "Convert namespace import to named imports";
+    const actionNameNamedToNamespace = "Convert named imports to namespace import";
+    registerRefactor(refactorName, {
+        getAvailableActions(context): ApplicableRefactorInfo[] | undefined {
+            const i = getImportToConvert(context);
+            if (!i) return undefined;
+            const description = i.kind === SyntaxKind.NamespaceImport ? Diagnostics.Convert_namespace_import_to_named_imports.message : Diagnostics.Convert_named_imports_to_namespace_import.message;
+            const actionName = i.kind === SyntaxKind.NamespaceImport ? actionNameNamespaceToNamed : actionNameNamedToNamespace;
+            return [{ name: refactorName, description, actions: [{ name: actionName, description }] }];
+        },
+        getEditsForAction(context, actionName): RefactorEditInfo {
+            Debug.assert(actionName === actionNameNamespaceToNamed || actionName === actionNameNamedToNamespace);
+            const edits = textChanges.ChangeTracker.with(context, t => doChange(context.file, context.program, t, Debug.assertDefined(getImportToConvert(context))));
+            return { edits, renameFilename: undefined, renameLocation: undefined };
+        }
+    });
+
+    // Can convert imports of the form `import * as m from "m";` or `import d, { x, y } from "m";`.
+    function getImportToConvert(context: RefactorContext): NamedImportBindings | undefined {
+        const { file } = context;
+        const span = getRefactorContextSpan(context);
+        const token = getTokenAtPosition(file, span.start, /*includeJsDocComment*/ false);
+        const importDecl = getParentNodeInSpan(token, file, span);
+        if (!importDecl || !isImportDeclaration(importDecl)) return undefined;
+        const { importClause } = importDecl;
+        return importClause && importClause.namedBindings;
+    }
+
+    function doChange(sourceFile: SourceFile, program: Program, changes: textChanges.ChangeTracker, toConvert: NamedImportBindings): void {
+        const usedIdentifiers = createMap<true>();
+        forEachFreeIdentifier(sourceFile, id => usedIdentifiers.set(id.text, true));
+        const checker = program.getTypeChecker();
+
+        if (toConvert.kind === SyntaxKind.NamespaceImport) {
+            doChangeNamespaceToNamed(sourceFile, checker, changes, toConvert, usedIdentifiers, getAllowSyntheticDefaultImports(program.getCompilerOptions()));
+        }
+        else {
+            doChangeNamedToNamespace(sourceFile, checker, changes, toConvert, usedIdentifiers);
+        }
+    }
+
+    function doChangeNamespaceToNamed(sourceFile: SourceFile, checker: TypeChecker, changes: textChanges.ChangeTracker, toConvert: NamespaceImport, usedIdentifiers: ReadonlyMap<true>, allowSyntheticDefaultImports: boolean): void {
+        // We may need to change `mod.x` to `_x` to avoid a name conflict.
+        const exportNameToImportName = createMap<string>();
+        let usedAsNamespaceOrDefault = false;
+
+        FindAllReferences.Core.eachSymbolReferenceInFile(toConvert.name, checker, sourceFile, id => {
+            if (!isPropertyAccessExpression(id.parent)) {
+                usedAsNamespaceOrDefault = true;
+            }
+            else {
+                const parent = cast(id.parent, isPropertyAccessExpression);
+                const exportName = parent.name.text;
+                let name = exportNameToImportName.get(exportName);
+                if (name === undefined) {
+                    exportNameToImportName.set(exportName, name = generateName(exportName, usedIdentifiers));
+                }
+                Debug.assert(parent.expression === id);
+                changes.replaceNode(sourceFile, parent, createIdentifier(name));
+            }
+        });
+
+        const elements: ImportSpecifier[] = [];
+        exportNameToImportName.forEach((name, propertyName) => {
+            elements.push(createImportSpecifier(name === propertyName ? undefined : createIdentifier(propertyName), createIdentifier(name)));
+        });
+        const makeImportDeclaration = (defaultImportName: Identifier | undefined) =>
+            createImportDeclaration(/*decorators*/ undefined, /*modifiers*/ undefined,
+                createImportClause(defaultImportName, elements.length ? createNamedImports(elements) : undefined),
+                toConvert.parent.parent.moduleSpecifier);
+
+        if (usedAsNamespaceOrDefault && !allowSyntheticDefaultImports) {
+            changes.insertNodeAfter(sourceFile, toConvert.parent.parent, makeImportDeclaration(/*defaultImportName*/ undefined));
+        }
+        else {
+            changes.replaceNode(sourceFile, toConvert.parent.parent, makeImportDeclaration(usedAsNamespaceOrDefault ? createIdentifier(toConvert.name.text) : undefined));
+        }
+    }
+
+    function doChangeNamedToNamespace(sourceFile: SourceFile, checker: TypeChecker, changes: textChanges.ChangeTracker, toConvert: NamedImports, usedIdentifiers: ReadonlyMap<true>): void {
+        const { moduleSpecifier } = toConvert.parent.parent;
+        // We know the user is using at least ScriptTarget.ES6, and moduleSpecifierToValidIdentifier only cares if we're using ES5+, so just set ScriptTarget.ESNext
+        const namespaceImportName = generateName(moduleSpecifier && isStringLiteral(moduleSpecifier) ? codefix.moduleSpecifierToValidIdentifier(moduleSpecifier.text, ScriptTarget.ESNext) : "module", usedIdentifiers);
+
+        changes.replaceNode(sourceFile, toConvert, createNamespaceImport(createIdentifier(namespaceImportName)));
+
+        for (const element of toConvert.elements) {
+            const propertyName = (element.propertyName || element.name).text;
+            FindAllReferences.Core.eachSymbolReferenceInFile(element.name, checker, sourceFile, id => {
+                changes.replaceNode(sourceFile, id, createPropertyAccess(createIdentifier(namespaceImportName), propertyName));
+            });
+        }
+    }
+
+    function generateName(name: string, usedIdentifiers: ReadonlyMap<true>): string {
+        while (usedIdentifiers.has(name)) {
+            name = `_${name}`;
+        }
+        return name;
+    }
+}

src/services/refactors/extractSymbol.ts

@@ -1744,23 +1744,6 @@ namespace ts.refactor.extractSymbol {
         }
     }
 
-    function getParentNodeInSpan(node: Node | undefined, file: SourceFile, span: TextSpan): Node | undefined {
-        if (!node) return undefined;
-
-        while (node.parent) {
-            if (isSourceFile(node.parent) || !spanContainsNode(span, node.parent, file)) {
-                return node;
-            }
-
-            node = node.parent;
-        }
-    }
-
-    function spanContainsNode(span: TextSpan, node: Node, file: SourceFile): boolean {
-        return textSpanContainsPosition(span, node.getStart(file)) &&
-            node.getEnd() <= textSpanEnd(span);
-    }
-
     /**
      * Computes whether or not a node represents an expression in a position where it could
      * be extracted.

src/services/tsconfig.json

@@ -113,6 +113,7 @@
         "codefixes/useDefaultImport.ts",
         "codefixes/fixAddModuleReferTypeMissingTypeof.ts",
         "codefixes/convertToMappedObjectType.ts",
+        "refactors/convertImport.ts",
         "refactors/extractSymbol.ts",
         "refactors/generateGetAccessorAndSetAccessor.ts",
         "refactors/moveToNewFile.ts",

src/services/utilities.ts

@@ -1309,6 +1309,46 @@ namespace ts {
             return forEachEntry(this.map, pred) || false;
         }
     }
+
+    export function getParentNodeInSpan(node: Node | undefined, file: SourceFile, span: TextSpan): Node | undefined {
+        if (!node) return undefined;
+
+        while (node.parent) {
+            if (isSourceFile(node.parent) || !spanContainsNode(span, node.parent, file)) {
+                return node;
+            }
+
+            node = node.parent;
+        }
+    }
+
+    function spanContainsNode(span: TextSpan, node: Node, file: SourceFile): boolean {
+        return textSpanContainsPosition(span, node.getStart(file)) &&
+            node.getEnd() <= textSpanEnd(span);
+    }
+
+    /**
+     * A free identifier is an identifier that can be accessed through name lookup as a local variable.
+     * In the expression `x.y`, `x` is a free identifier, but `y` is not.
+     */
+    export function forEachFreeIdentifier(node: Node, cb: (id: Identifier) => void): void {
+        if (isIdentifier(node) && isFreeIdentifier(node)) cb(node);
+        node.forEachChild(child => forEachFreeIdentifier(child, cb));
+    }
+
+    function isFreeIdentifier(node: Identifier): boolean {
+        const { parent } = node;
+        switch (parent.kind) {
+            case SyntaxKind.PropertyAccessExpression:
+                return (parent as PropertyAccessExpression).name !== node;
+            case SyntaxKind.BindingElement:
+                return (parent as BindingElement).propertyName !== node;
+            case SyntaxKind.ImportSpecifier:
+                return (parent as ImportSpecifier).propertyName !== node;
+            default:
+                return true;
+        }
+    }
 }
 
 // Display-part writer helpers

tests/cases/fourslash/refactorConvertImport_namedToNamespace.ts

@@ -0,0 +1,20 @@
+/// <reference path='fourslash.ts' />
+
+/////*a*/import { x, y as z, T } from "m";/*b*/
+////const m = 0;
+////x;
+////z;
+////const n: T = 0;
+
+goTo.select("a", "b");
+edit.applyRefactor({
+    refactorName: "Convert import",
+    actionName: "Convert named imports to namespace import",
+    actionDescription: "Convert named imports to namespace import",
+    newContent:
+`import * as _m from "m";
+const m = 0;
+_m.x;
+_m.y;
+const n: _m.T = 0;`,
+});

tests/cases/fourslash/refactorConvertImport_namespaceToNamed.ts

@@ -0,0 +1,18 @@
+/// <reference path='fourslash.ts' />
+
+/////*a*/import * as m from "m";/*b*/
+////const a = 0;
+////m.a;
+////m.b;
+
+goTo.select("a", "b");
+edit.applyRefactor({
+    refactorName: "Convert import",
+    actionName: "Convert namespace import to named imports",
+    actionDescription: "Convert namespace import to named imports",
+    newContent:
+`import { a as _a, b } from "m";
+const a = 0;
+_a;
+b;`,
+});

tests/cases/fourslash/refactorConvertImport_namespaceToNamed_namespaceUsed.ts

@@ -0,0 +1,17 @@
+/// <reference path='fourslash.ts' />
+
+/////*a*/import * as m from "m";/*b*/
+////m.a;
+////m;
+
+goTo.select("a", "b");
+edit.applyRefactor({
+    refactorName: "Convert import",
+    actionName: "Convert namespace import to named imports",
+    actionDescription: "Convert namespace import to named imports",
+    newContent:
+`import * as m from "m";
+import { a } from "m";
+a;
+m;`,
+});

tests/cases/fourslash/refactorConvertImport_notAtDefaultName.ts

@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts' />
+
+////import /*a*/d/*b*/, * as n from "m";
+
+goTo.select("a", "b");
+verify.not.refactorAvailable("Convert import");

tests/cases/fourslash/refactorConvertImport_useDefault.ts

@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts' />
+
+// @allowSyntheticDefaultImports: true
+
+/////*a*/import * as m from "m";/*b*/
+////m();
+
+goTo.select("a", "b");
+edit.applyRefactor({
+    refactorName: "Convert import",
+    actionName: "Convert namespace import to named imports",
+    actionDescription: "Convert namespace import to named imports",
+    newContent:
+`import m from "m";
+m();`,
+});