1 files changed, 35 insertions, 0 deletions
diff --git a/toolkit/components/uniffi-bindgen-gecko-js/src/templates/js/Optional.jsm b/toolkit/components/uniffi-bindgen-gecko-js/src/templates/js/Optional.jsm
new file mode 100644
index 0000000000..eaa96fe55e
--- /dev/null
+++ b/toolkit/components/uniffi-bindgen-gecko-js/src/templates/js/Optional.jsm
@@ -0,0 +1,35 @@
+class {{ ffi_converter }} extends FfiConverterArrayBuffer {
+    static checkType(name, value) {
+        if (value !== undefined && value !== null) {
+            {{ inner.ffi_converter() }}.checkType(name, value)
+        }
+    }
+
+    static read(dataStream) {
+        const code = dataStream.readUint8(0);
+        switch (code) {
+            case 0:
+                return null
+            case 1:
+                return {{ inner.ffi_converter() }}.read(dataStream)
+            default:
+                throw UniFFIError(`Unexpected code: ${code}`);
+        }
+    }
+
+    static write(dataStream, value) {
+        if (value === null || value === undefined) {
+            dataStream.writeUint8(0);
+            return;
+        }
+        dataStream.writeUint8(1);
+        {{ inner.ffi_converter() }}.write(dataStream, value)
+    }
+
+    static computeSize(value) {
+        if (value === null || value === undefined) {
+            return 1;
+        }
+        return 1 + {{ inner.ffi_converter() }}.computeSize(value)
+    }
+}