bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'editors/code/src/nullable.ts')
-rw-r--r--editors/code/src/nullable.ts19
1 files changed, 19 insertions, 0 deletions
diff --git a/editors/code/src/nullable.ts b/editors/code/src/nullable.ts
new file mode 100644
index 0000000000..e973e16290
--- /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\``);
+}