1 files changed, 58 insertions, 0 deletions
diff --git a/u/trace/util.ts b/u/trace/util.ts
new file mode 100644
index 0000000..302c8e4
--- /dev/null
+++ b/u/trace/util.ts
@@ -0,0 +1,58 @@
+import type {
+  Callable,
+  IMetric,
+  ITraceableMapper,
+  ITraceableTuple,
+  MetricsTraceSupplier,
+} from "@emprespresso/pengueno";
+
+export class TraceUtil {
+  static withTrace<T, Trace>(
+    trace: string,
+  ): ITraceableMapper<
+    T,
+    ITraceableTuple<T, Trace | Array<Trace>>,
+    Trace
+  > {
+    return (t) => [t.get(), `[${trace}]`];
+  }
+
+  static withMetricTrace<T, Trace extends MetricsTraceSupplier>(
+    metric: IMetric,
+  ): ITraceableMapper<
+    T,
+    ITraceableTuple<T, Trace | Array<Trace>>,
+    Trace
+  > {
+    return (t) => [t.get(), metric as Trace];
+  }
+
+  static withFunctionTrace<F extends Callable, T, Trace>(
+    f: F,
+  ): ITraceableMapper<
+    T,
+    ITraceableTuple<T, Trace | Array<Trace>>,
+    Trace
+  > {
+    return TraceUtil.withTrace(f.name);
+  }
+
+  static withClassTrace<C extends object, T, Trace>(
+    c: C,
+  ): ITraceableMapper<
+    T,
+    ITraceableTuple<T, Trace | Array<Trace>>,
+    Trace
+  > {
+    return TraceUtil.withTrace(c.constructor.name);
+  }
+
+  static promiseify<T, U, Trace>(
+    mapper: ITraceableMapper<T, U, Trace>,
+  ): ITraceableMapper<Promise<T>, Promise<U>, Trace> {
+    return (traceablePromise) =>
+      traceablePromise.flatMapAsync(async (t) =>
+        t.move(await t.get()).map(mapper)
+      ).get();
+  }
+}