Initial Commit

packages/foundation/bitpacker/bitpacker-strategies/src/strategies/optional/optional.ts

@@ -0,0 +1,37 @@
+import type {
+    BitPackerSchema,
+    PackingContext,
+    PackingStrategy,
+} from "@suaveplan/bitpacker";
+import { isOptionalSchema } from "@suaveplan/bitpacker";
+
+export class OptionalPackingStrategy implements PackingStrategy {
+    canHandle(schema: BitPackerSchema): boolean {
+        return isOptionalSchema(schema);
+    }
+
+    pack(
+        data: unknown,
+        schema: BitPackerSchema,
+        context: PackingContext
+    ): void {
+        const { _optional: inner } = schema as { _optional: BitPackerSchema };
+
+        const present = data !== undefined && data !== null;
+        context.writer.writeBool(present);
+
+        if (present) {
+            context.packValue(data, inner);
+        }
+    }
+
+    unpack(schema: BitPackerSchema, context: PackingContext): unknown {
+        const { _optional: inner } = schema as { _optional: BitPackerSchema };
+
+        const present = context.reader.readBool();
+        if (!present) {
+            return undefined;
+        }
+        return context.unpackValue(inner);
+    }
+}