From 4629db6b0dbc88c6d7f7e8eb23996138f96dbda9 Mon Sep 17 00:00:00 2001
From: Lucas Azzola <derflatulator@gmail.com>
Date: Sun, 7 May 2017 01:00:26 +1000
Subject: [PATCH] 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                              |  8 ++++
 src/printer.js                                | 18 ++++++--
 .../compiler/__snapshots__/jsfmt.spec.js.snap | 42 ++++++++++++++-----
 .../compiler/indexSignatureWithInitializer.ts |  8 ++++
 .../__snapshots__/jsfmt.spec.js.snap          | 39 +++++++++++++++++
 .../custom/computedProperties/jsfmt.spec.js   |  1 +
 .../custom/computedProperties/string.ts       |  7 ++++
 .../custom/computedProperties/symbol.ts       |  7 ++++
 8 files changed, 115 insertions(+), 15 deletions(-)
 create mode 100644 tests/typescript/compiler/indexSignatureWithInitializer.ts
 create mode 100644 tests/typescript/custom/computedProperties/__snapshots__/jsfmt.spec.js.snap
 create mode 100644 tests/typescript/custom/computedProperties/jsfmt.spec.js
 create mode 100644 tests/typescript/custom/computedProperties/string.ts
 create mode 100644 tests/typescript/custom/computedProperties/symbol.ts

diff --git a/src/fast-path.js b/src/fast-path.js
index 5e982383..08612351 100644
--- a/src/fast-path.js
+++ b/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)
diff --git a/src/printer.js b/src/printer.js
index 5b129629..bbff7bf4 100644
--- a/src/printer.js
+++ b/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(": ");
diff --git a/tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap b/tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap
index 0d493b12..f2b65a12 100644
--- a/tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap
+++ b/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
 
diff --git a/tests/typescript/compiler/indexSignatureWithInitializer.ts b/tests/typescript/compiler/indexSignatureWithInitializer.ts
new file mode 100644
index 00000000..f9a4aafc
--- /dev/null
+++ b/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
+}
\ No newline at end of file
diff --git a/tests/typescript/custom/computedProperties/__snapshots__/jsfmt.spec.js.snap b/tests/typescript/custom/computedProperties/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 00000000..638d8d04
--- /dev/null
+++ b/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"
+};
+
+`;
diff --git a/tests/typescript/custom/computedProperties/jsfmt.spec.js b/tests/typescript/custom/computedProperties/jsfmt.spec.js
new file mode 100644
index 00000000..bc085c48
--- /dev/null
+++ b/tests/typescript/custom/computedProperties/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, { parser: "typescript" });
diff --git a/tests/typescript/custom/computedProperties/string.ts b/tests/typescript/custom/computedProperties/string.ts
new file mode 100644
index 00000000..e003c31f
--- /dev/null
+++ b/tests/typescript/custom/computedProperties/string.ts
@@ -0,0 +1,7 @@
+interface I {
+    "string": "I";
+}
+
+type T = {
+    "string": "T";
+}
diff --git a/tests/typescript/custom/computedProperties/symbol.ts b/tests/typescript/custom/computedProperties/symbol.ts
new file mode 100644
index 00000000..5da83454
--- /dev/null
+++ b/tests/typescript/custom/computedProperties/symbol.ts
@@ -0,0 +1,7 @@
+interface I {
+    [Symbol.toStringTag]: "I";
+}
+
+type T = {
+    [Symbol.toStringTag]: "T";
+}