From 72a3883a7128b4eae6f38d6479f33aaaaae4790b Mon Sep 17 00:00:00 2001
From: Tetsuharu Ohzeki <tetsuharu.ohzeki@gmail.com>
Date: Wed, 28 Jun 2023 04:03:53 +0900
Subject: editor/code: Enable `noUncheckedIndexedAccess` ts option

https://www.typescriptlang.org/tsconfig#noUncheckedIndexedAccess
---
 editors/code/src/nullable.ts | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 editors/code/src/nullable.ts

(limited to 'editors/code/src/nullable.ts')

diff --git a/editors/code/src/nullable.ts b/editors/code/src/nullable.ts
new file mode 100644
index 00000000000..e973e162907
--- /dev/null
+++ b/editors/code/src/nullable.ts
@@ -0,0 +1,19 @@
+export type NotNull<T> = T extends null ? never : T;
+
+export type Nullable<T> = T | null;
+
+function isNotNull<T>(input: Nullable<T>): input is NotNull<T> {
+    return input !== null;
+}
+
+function expectNotNull<T>(input: Nullable<T>, msg: string): NotNull<T> {
+    if (isNotNull(input)) {
+        return input;
+    }
+
+    throw new TypeError(msg);
+}
+
+export function unwrapNullable<T>(input: Nullable<T>): NotNull<T> {
+    return expectNotNull(input, `unwrapping \`null\``);
+}
-- 
cgit 1.4.1-3-g733a5