add refactoring: string concatenation to template literals

src/compiler/diagnosticMessages.json

@@ -5341,6 +5341,10 @@
         "category": "Message",
         "code": 95095
     },
+    "Convert to template string": {
+        "category": "Message",
+        "code": 95096
+    },
 
     "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer.": {
         "category": "Error",

src/services/refactors/convertStringOrTemplateLiteral.ts

@@ -0,0 +1,186 @@
+/* @internal */
+namespace ts.refactor.convertStringOrTemplateLiteral {
+    const refactorName = "Convert to template string";
+    const refactorDescription = getLocaleSpecificMessage(Diagnostics.Convert_to_template_string);
+
+    registerRefactor(refactorName, { getEditsForAction, getAvailableActions });
+
+    function getAvailableActions(context: RefactorContext): readonly ApplicableRefactorInfo[] {
+        const { file, startPosition } = context;
+        const node = getNodeOrParentOfParentheses(file, startPosition);
+        const maybeBinary = getParentBinaryExpression(node);
+        const refactorInfo: ApplicableRefactorInfo = { name: refactorName, description: refactorDescription, actions: [] };
+
+        if ((isBinaryExpression(maybeBinary) || isStringLiteral(maybeBinary)) && isStringConcatenationValid(maybeBinary)) {
+            refactorInfo.actions.push({ name: refactorName, description: refactorDescription });
+            return [refactorInfo];
+        }
+        return emptyArray;
+    }
+
+    function getNodeOrParentOfParentheses(file: SourceFile, startPosition: number) {
+        const node = getTokenAtPosition(file, startPosition);
+        const nestedBinary = getParentBinaryExpression(node);
+        const isNonStringBinary = !isStringConcatenationValid(nestedBinary);
+
+        if (
+            isNonStringBinary &&
+            isParenthesizedExpression(nestedBinary.parent) &&
+            isBinaryExpression(nestedBinary.parent.parent)
+        ) {
+            return nestedBinary.parent.parent;
+        }
+        return node;
+    }
+
+    function getEditsForAction(context: RefactorContext, actionName: string): RefactorEditInfo | undefined {
+        const { file, startPosition } = context;
+        const node = getNodeOrParentOfParentheses(file, startPosition);
+
+        switch (actionName) {
+            case refactorDescription:
+                return { edits: getEditsForToTemplateLiteral(context, node) };
+            default:
+                return Debug.fail("invalid action");
+        }
+    }
+
+    function getEditsForToTemplateLiteral(context: RefactorContext, node: Node) {
+        const maybeBinary = getParentBinaryExpression(node);
+        const file = context.file;
+
+        const templateLiteral = nodesToTemplate(treeToArray(maybeBinary), file);
+        const trailingCommentRanges = getTrailingCommentRanges(file.text, maybeBinary.end);
+
+        if (trailingCommentRanges) {
+            const lastComment = trailingCommentRanges[trailingCommentRanges.length - 1];
+            const trailingRange = { pos: trailingCommentRanges[0].pos, end: lastComment.end };
+
+            // since suppressTrailingTrivia(maybeBinary) does not work, the trailing comment is removed manually
+            // otherwise it would have the trailing comment twice
+            return textChanges.ChangeTracker.with(context, t => {
+                t.deleteRange(file, trailingRange);
+                t.replaceNode(file, maybeBinary, templateLiteral);
+            });
+        }
+        else {
+            return textChanges.ChangeTracker.with(context, t => t.replaceNode(file, maybeBinary, templateLiteral));
+        }
+    }
+
+    function isNotEqualsOperator(node: BinaryExpression) {
+        return node.operatorToken.kind !== SyntaxKind.EqualsToken;
+    }
+
+    function getParentBinaryExpression(expr: Node) {
+        while (isBinaryExpression(expr.parent) && isNotEqualsOperator(expr.parent)) {
+            expr = expr.parent;
+        }
+        return expr;
+    }
+
+    function isStringConcatenationValid(node: Node): boolean {
+        const { containsString, areOperatorsValid } = treeToArray(node);
+        return containsString && areOperatorsValid;
+    }
+
+    function treeToArray(current: Node): { nodes: Expression[], operators: Token<BinaryOperator>[], containsString: boolean, areOperatorsValid: boolean} {
+        if (isBinaryExpression(current)) {
+            const { nodes, operators, containsString: leftHasString, areOperatorsValid: leftOperatorValid } = treeToArray(current.left);
+
+            if (!leftHasString && !isStringLiteral(current.right)) {
+                return { nodes: [current], operators: [], containsString: false, areOperatorsValid: true };
+            }
+
+            const currentOperatorValid = current.operatorToken.kind === SyntaxKind.PlusToken;
+            const areOperatorsValid = leftOperatorValid && currentOperatorValid;
+
+            nodes.push(current.right);
+            operators.push(current.operatorToken);
+
+            return { nodes, operators, containsString: true, areOperatorsValid };
+        }
+
+        return { nodes: [current as Expression], operators: [], containsString: isStringLiteral(current), areOperatorsValid: true };
+    }
+
+    // to copy comments following the operator
+    // "foo" + /* comment */ "bar"
+    const copyTrailingOperatorComments = (operators: Token<BinaryOperator>[], file: SourceFile) => (index: number, targetNode: Node) => {
+        if (index < operators.length) {
+             copyTrailingComments(operators[index], targetNode, file, SyntaxKind.MultiLineCommentTrivia, /* hasTrailingNewLine */ false);
+        }
+    };
+
+    // to copy comments following the string
+    // "foo" /* comment */ + "bar" /* comment */ + "bar2"
+    const copyCommentFromMultiNode = (nodes: readonly Expression[], file: SourceFile, copyOperatorComments: (index: number, targetNode: Node) => void) =>
+    (indexes: number[], targetNode: Node) => {
+        while (indexes.length > 0) {
+            const index = indexes.shift()!;
+            copyTrailingComments(nodes[index], targetNode, file, SyntaxKind.MultiLineCommentTrivia, /* hasTrailingNewLine */ false);
+            copyOperatorComments(index, targetNode);
+        }
+    };
+
+    function concatConsecutiveString(index: number, nodes: readonly Expression[]): [number, string, number[]] {
+        let text = "";
+        const indexes = [];
+
+        while (index < nodes.length && isStringLiteral(nodes[index])) {
+            const stringNode = nodes[index] as StringLiteral;
+            text = text + stringNode.text;
+            indexes.push(index);
+            index++;
+        }
+
+        text = escapeString(text);
+        return [index, text, indexes];
+    }
+
+    function nodesToTemplate({nodes, operators}: {nodes: readonly Expression[], operators: Token<BinaryOperator>[]}, file: SourceFile) {
+        const copyOperatorComments = copyTrailingOperatorComments(operators, file);
+        const copyCommentFromStringLiterals = copyCommentFromMultiNode(nodes, file, copyOperatorComments);
+        const [begin, headText, headIndexes] = concatConsecutiveString(0, nodes);
+
+        if (begin === nodes.length) {
+            const noSubstitutionTemplateLiteral = createNoSubstitutionTemplateLiteral(headText);
+            copyCommentFromStringLiterals(headIndexes, noSubstitutionTemplateLiteral);
+            return noSubstitutionTemplateLiteral;
+        }
+
+        const templateSpans: TemplateSpan[] = [];
+        const templateHead = createTemplateHead(headText);
+        copyCommentFromStringLiterals(headIndexes, templateHead);
+
+        for (let i = begin; i < nodes.length; i++) {
+            const currentNode = getExpressionFromParenthesesOrExpression(nodes[i]);
+            copyOperatorComments(i, currentNode);
+
+            const [newIndex, subsequentText, stringIndexes] = concatConsecutiveString(i + 1, nodes);
+            i = newIndex - 1;
+
+            const templatePart = i === nodes.length - 1 ? createTemplateTail(subsequentText) : createTemplateMiddle(subsequentText);
+            copyCommentFromStringLiterals(stringIndexes, templatePart);
+            templateSpans.push(createTemplateSpan(currentNode, templatePart));
+        }
+
+        return createTemplateExpression(templateHead, templateSpans);
+    }
+
+    // to copy comments following the opening & closing parentheses
+    // "foo" + ( /* comment */ 5 + 5 ) /* comment */ + "bar"
+    function copyCommentsWhenParenthesized(node: ParenthesizedExpression) {
+        const file = node.getSourceFile();
+        copyTrailingComments(node, node.expression, file, SyntaxKind.MultiLineCommentTrivia, /* hasTrailingNewLine */ false);
+        copyTrailingAsLeadingComments(node.expression, node.expression, file, SyntaxKind.MultiLineCommentTrivia, /* hasTrailingNewLine */ false);
+    }
+
+    function getExpressionFromParenthesesOrExpression(node: Expression) {
+        if (isParenthesizedExpression(node)) {
+            copyCommentsWhenParenthesized(node);
+            node = node.expression;
+        }
+        return node;
+    }
+}

src/services/tsconfig.json

@@ -94,6 +94,7 @@
         "refactors/moveToNewFile.ts",
         "refactors/addOrRemoveBracesToArrowFunction.ts",
         "refactors/convertParamsToDestructuredObject.ts",
+        "refactors/convertStringOrTemplateLiteral.ts",
         "services.ts",
         "breakpoints.ts",
         "transform.ts",

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateAsFnArgument.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// console.log("/*x*/f/*y*/oobar is " + 32 + " years old")
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+`console.log(\`foobar is \${32} years old\`)`,
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateBackTick.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = "/*x*/w/*y*/ith back`tick"
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = `with back\\`tick`",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateBinaryExpr.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = "/*x*/f/*y*/oobar is " + (42 + 6) + " years old"
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+`const foo = \`foobar is \${42 + 6} years old\``,
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateBinaryExprInEnding.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = "/*x*/f/*y*/oobar is " + (42 + 6)
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = `foobar is \${42 + 6}`",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateComment.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = /* C0 */ /*x*/"/*y*/foo" /* C1 */ + " is" /* C2 */ + 42 /* C3 */ + " and bar" /* C4 */ + " is" /* C5 */ + 52/* C6 */
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = /* C0 */ `foo is\${ /* C1 */ /* C2 */42 /* C3 */} and bar is\${ /* C4 */ /* C5 */52 /* C6 */}`",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateCommentAfterOperator.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = /* C0 */ /*x*/"/*y*/foo" + /* C1 */ " is" + /* C2 */ 42 + /* C3 */ " and bar" + /* C4 */ " is" + /* C5 */ 52/* C6 */
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = /* C0 */ `foo is\${ /* C1 */ /* C2 */42 /* C3 */} and bar is\${ /* C4 */ /* C5 */52 /* C6 */}`",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateCommentNoExpr.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = /* C0 */ /*x*/"/*y*/foo" /* C1 */ + " is"/* C2 */ /* C3 */
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = /* C0 */ `foo is` /* C1 */ /* C2 */ /* C3 */",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateCommentParenth.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = /*x*/"/*y*/foobar is" + ( /* C1 */ 42 ) /* C2 */ + /* C3 */ " years old"
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = `foobar is\${/* C1 */ 42 /* C2 */ /* C3 */} years old`",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateCommentTrailingExpr.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = /* C0 */ /*x*/"/*y*/foo" /* C1 */ + " is" /* C2 */ + 42/* C3 */
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = /* C0 */ `foo is\${ /* C1 */ /* C2 */42 /* C3 */}`",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateCommentTrailingStr.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = /* C0 */ /*x*/"/*y*/foo" /* C1 */ + " is" /* C2 */ + 42 + " years old"/* C3 */
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = /* C0 */ `foo is\${ /* C1 */ /* C2 */42} years old` /* C3 */",
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateConsecutiveStr.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = "/*x*/f/*y*/oobar is " + 42 + " years" + " old" + " and " + 6 + " cars" + " are" + " missing"
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+`const foo = \`foobar is \${42} years old and \${6} cars are missing\``,
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateMultiExpr.ts

@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts' />
+
+//// const age = 22
+//// const name = "Eddy"
+//// const foo = /*x*/n/*y*/ame + " is " + age + " years old"
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+`const age = 22
+const name = "Eddy"
+const foo = \`\${name} is \${age} years old\``,
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateOneExpr.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+//// const age = 42
+//// const foo = "/*x*/f/*y*/oobar is " + age + " years old"
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+`const age = 42
+const foo = \`foobar is \${age} years old\``,
+});

tests/cases/fourslash/refactorConvertStringOrTemplateLiteral_ToTemplateOnlyStr.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// const foo = "/*x*/f/*y*/oobar " + "rocks" + " fantastically"
+
+goTo.select("x", "y");
+edit.applyRefactor({
+    refactorName: "Convert to template string",
+    actionName: "Convert to template string",
+    actionDescription: ts.Diagnostics.Convert_to_template_string.message,
+    newContent:
+"const foo = `foobar rocks fantastically`",
+});