From e6f5640e76e87d08a9463bc551e6a9160318a088 Mon Sep 17 00:00:00 2001
From: Franz Becker <franzbecker@monzo.com>
Date: Tue, 31 Aug 2021 13:36:28 +0100
Subject: [PATCH 1/2] support transformation of symbol

---
 src/transform.ts                                         | 5 +++++
 test/fixtures/convert/basic-types/symbol01/flow.js       | 1 +
 test/fixtures/convert/basic-types/symbol01/ts.js         | 1 +
 test/fixtures/convert/intersection-union/union02/flow.js | 1 +
 test/fixtures/convert/intersection-union/union02/ts.js   | 1 +
 5 files changed, 9 insertions(+)
 create mode 100644 test/fixtures/convert/basic-types/symbol01/flow.js
 create mode 100644 test/fixtures/convert/basic-types/symbol01/ts.js
 create mode 100644 test/fixtures/convert/intersection-union/union02/flow.js
 create mode 100644 test/fixtures/convert/intersection-union/union02/ts.js

diff --git a/src/transform.ts b/src/transform.ts
index c6b8712f..d9a72eaf 100644
--- a/src/transform.ts
+++ b/src/transform.ts
@@ -277,6 +277,11 @@ export const transform = {
       path.replaceWith(t.tsArrayType(elementType));
     },
   },
+  SymbolTypeAnnotation: {
+    exit(path) {
+      path.replaceWith(t.tsSymbolKeyword());
+    },
+  },
   TupleTypeAnnotation: {
     exit(path) {
       const { types } = path.node;
diff --git a/test/fixtures/convert/basic-types/symbol01/flow.js b/test/fixtures/convert/basic-types/symbol01/flow.js
new file mode 100644
index 00000000..5bd5f8b9
--- /dev/null
+++ b/test/fixtures/convert/basic-types/symbol01/flow.js
@@ -0,0 +1 @@
+let a: symbol;
diff --git a/test/fixtures/convert/basic-types/symbol01/ts.js b/test/fixtures/convert/basic-types/symbol01/ts.js
new file mode 100644
index 00000000..5bd5f8b9
--- /dev/null
+++ b/test/fixtures/convert/basic-types/symbol01/ts.js
@@ -0,0 +1 @@
+let a: symbol;
diff --git a/test/fixtures/convert/intersection-union/union02/flow.js b/test/fixtures/convert/intersection-union/union02/flow.js
new file mode 100644
index 00000000..50ad4997
--- /dev/null
+++ b/test/fixtures/convert/intersection-union/union02/flow.js
@@ -0,0 +1 @@
+let obj: string | symbol;
diff --git a/test/fixtures/convert/intersection-union/union02/ts.js b/test/fixtures/convert/intersection-union/union02/ts.js
new file mode 100644
index 00000000..50ad4997
--- /dev/null
+++ b/test/fixtures/convert/intersection-union/union02/ts.js
@@ -0,0 +1 @@
+let obj: string | symbol;

From a8ffde3a808b1a7ab0036bdae0d5c8b37fa2d771 Mon Sep 17 00:00:00 2001
From: Franz Becker <franzbecker@monzo.com>
Date: Fri, 17 Sep 2021 17:36:40 +0100
Subject: [PATCH 2/2] add support for well known symbols

---
 src/transforms/object-type.ts                     | 15 ++++++++++++---
 .../interface-well-known-symbol01/flow.js         |  3 +++
 .../interface-well-known-symbol01/ts.js           |  3 +++
 3 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 test/fixtures/convert/interfaces/interface-well-known-symbol01/flow.js
 create mode 100644 test/fixtures/convert/interfaces/interface-well-known-symbol01/ts.js

diff --git a/src/transforms/object-type.ts b/src/transforms/object-type.ts
index 84798ca9..84548aba 100644
--- a/src/transforms/object-type.ts
+++ b/src/transforms/object-type.ts
@@ -138,8 +138,8 @@ export const ObjectTypeCallProperty = {
 
 export const ObjectTypeProperty = {
   exit(path, state) {
+    let { key } = path.node;
     const {
-      key,
       value,
       optional,
       variance,
@@ -151,9 +151,8 @@ export const ObjectTypeProperty = {
     } = path.node; // TODO: static, kind
     const typeAnnotation = t.tsTypeAnnotation(value);
     const initializer = undefined; // TODO: figure out when this used
-    const computed = false; // TODO: maybe set this to true for indexers
+    let computed = false;
     const readonly = variance && variance.kind === "plus";
-
     if (variance && variance.kind === "minus") {
       // TODO: include file and location of infraction
       console.warn("typescript doesn't support writeonly properties");
@@ -162,6 +161,16 @@ export const ObjectTypeProperty = {
       console.warn("we don't handle get() or set() yet, :P");
     }
 
+    if (t.isIdentifier(key)) {
+      if (key.name.startsWith("@@")) {
+        key = t.memberExpression(
+          t.identifier("Symbol"),
+          t.identifier(key.name.replace("@@", ""))
+        );
+        computed = true;
+      }
+    }
+
     if (method) {
       // TODO: assert value is a FunctionTypeAnnotation
       const methodSignature = {
diff --git a/test/fixtures/convert/interfaces/interface-well-known-symbol01/flow.js b/test/fixtures/convert/interfaces/interface-well-known-symbol01/flow.js
new file mode 100644
index 00000000..fb9f1323
--- /dev/null
+++ b/test/fixtures/convert/interfaces/interface-well-known-symbol01/flow.js
@@ -0,0 +1,3 @@
+interface Iterable<T> {
+  @@iterator(): Iterator<T>;
+}
diff --git a/test/fixtures/convert/interfaces/interface-well-known-symbol01/ts.js b/test/fixtures/convert/interfaces/interface-well-known-symbol01/ts.js
new file mode 100644
index 00000000..3432ec74
--- /dev/null
+++ b/test/fixtures/convert/interfaces/interface-well-known-symbol01/ts.js
@@ -0,0 +1,3 @@
+interface Iterable<T> {
+  [Symbol.iterator](): Iterator<T>;
+}
\ No newline at end of file