TypeScript: improve handling of computed properties (#1532)

* fix(typescript): improve handling of computed properties

* test(typescript): add Symbol computed property test

* fix(typescript): do not print brackets for literals

src/fast-path.js

@@ -445,6 +445,14 @@ FPp.needsParens = function() {
     case "AssignmentExpression":
       if (parent.type === "ArrowFunctionExpression" && parent.body === node) {
         return true;
+      } else if (
+        parent.type === "ClassProperty" &&
+        parent.key === node &&
+        parent.computed
+      ) {
+        return false;
+      } else if (parent.type === "TSPropertySignature" && parent.name === node) {
+        return false;
       } else if (
         parent.type === "ForStatement" &&
         (parent.init === node || parent.update === node)

src/printer.js

@@ -2093,10 +2093,20 @@ function genericPrintNoParens(path, options, print, args) {
     case "TSArrayType":
       return concat([path.call(print, "elementType"), "[]"]);
     case "TSPropertySignature":
-      parts.push(
-        printTypeScriptModifiers(path, options, print),
-        path.call(print, "name")
-      );
+      var computed = !namedTypes.Identifier.check(n.name) &&
+        !namedTypes.Literal.check(n.name);
+
+      parts.push(printTypeScriptModifiers(path, options, print));
+
+      if (computed) {
+        parts.push("[");
+      }
+
+      parts.push(path.call(print, "name"));
+
+      if (computed) {
+        parts.push("]");
+      }
 
       if (n.typeAnnotation) {
         parts.push(": ");

tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap

@@ -7,17 +7,6 @@ var results = number[];
 
 `;
 
-exports[`commentsInterface.ts 1`] = `
-interface i2 {
-    foo: (/**param help*/b: number) => string;
-}
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-interface i2 {
-  foo: (/**param help*/ b: number) => string
-}
-
-`;
-
 exports[`checkInfiniteExpansionTermination.ts 1`] = `
 // Regression test for #1002
 // Before fix this code would cause infinite loop
@@ -55,6 +44,17 @@ values = values2;
 
 `;
 
+exports[`commentsInterface.ts 1`] = `
+interface i2 {
+    foo: (/**param help*/b: number) => string;
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+interface i2 {
+  foo: (/**param help*/ b: number) => string
+}
+
+`;
+
 exports[`functionOverloadsOnGenericArity1.ts 1`] = `
 // overloading on arity not allowed
 interface C {
@@ -82,6 +82,26 @@ interface C {
 
 `;
 
+exports[`indexSignatureWithInitializer.ts 1`] = `
+// These used to be indexers, now they are computed properties
+interface I {
+    [x = '']: string;
+}
+
+class C {
+    [x = 0]: string
+}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// These used to be indexers, now they are computed properties
+interface I {
+  [x = ""]: string
+}
+
+class C {
+  [x = 0]: string;
+}
+
+`;
+
 exports[`mappedTypeWithCombinedTypeMappers.ts 1`] = `
 // Repro from #13351
 

tests/typescript/compiler/indexSignatureWithInitializer.ts

@@ -0,0 +1,8 @@
+// These used to be indexers, now they are computed properties
+interface I {
+    [x = '']: string;
+}
+
+class C {
+    [x = 0]: string
+}

tests/typescript/custom/computedProperties/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,39 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`string.ts 1`] = `
+interface I {
+    "string": "I";
+}
+
+type T = {
+    "string": "T";
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+interface I {
+  "string": "I"
+}
+
+type T = {
+  "string": "T"
+};
+
+`;
+
+exports[`symbol.ts 1`] = `
+interface I {
+    [Symbol.toStringTag]: "I";
+}
+
+type T = {
+    [Symbol.toStringTag]: "T";
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+interface I {
+  [Symbol.toStringTag]: "I"
+}
+
+type T = {
+  [Symbol.toStringTag]: "T"
+};
+
+`;

tests/typescript/custom/computedProperties/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname, { parser: "typescript" });

tests/typescript/custom/computedProperties/string.ts

@@ -0,0 +1,7 @@
+interface I {
+    "string": "I";
+}
+
+type T = {
+    "string": "T";
+}

tests/typescript/custom/computedProperties/symbol.ts

@@ -0,0 +1,7 @@
+interface I {
+    [Symbol.toStringTag]: "I";
+}
+
+type T = {
+    [Symbol.toStringTag]: "T";
+}