initial import

2026-07-19 13:44:10 -07:00
commit 10f2d98ada
10 changed files with 619 additions and 0 deletions
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+/**
+ * push-take-until - Take elements until signal stream emits
+ *
+ * Uses canonical push-stream pattern:
+ * - This is a sink that wraps a signal stream
+ * - When signal ends, the take-until ends
+ * - Pass through all values until signal fires
+ *
+ * API:
+ * import takeUntil from 'push-take-until'
+ *
+ * const untilClick = takeUntil(clickStream)
+ * source.pipe(untilClick).pipe(sink)
+ */
+
+export function takeUntil(signalStream) {
+  let source = null;
+  let sink = null;
+  let isEnded = false;
+  let signalEnded = false;
+
+  const stream = {
+    get paused() { return false; },
+    get ended() { return isEnded; },
+
+    pipe(s) {
+      if (isEnded) {
+        s.end();
+        return s;
+      }
+      sink = s;
+      try { s.source = stream; } catch (e) {}
+      return s;
+    },
+
+    write(data) {
+      if (isEnded || signalEnded) return;
+      if (sink && !sink.paused) {
+        sink.write(data);
+      }
+    },
+
+    end(err) {
+      if (isEnded) return;
+      isEnded = true;
+      if (source && source.end) source.end(err);
+      if (sink) sink.end(err);
+    },
+
+    abort(err) {
+      if (isEnded) return;
+      isEnded = true;
+      if (source && source.abort) source.abort(err);
+      if (sink) sink.end(err);
+    },
+
+    resume() {
+      if (source && source.resume) source.resume();
+    },
+
+    get source() { return source; },
+    set source(s) { source = s; }
+  };
+
+  signalStream.pipe({
+    write() {},
+    end() {
+      if (signalEnded) return;
+      signalEnded = true;
+
+      if (!isEnded) {
+        isEnded = true;
+        if (source && source.end) source.end();
+        if (sink) sink.end();
+      }
+    },
+    abort(err) {
+      if (signalEnded) return;
+      signalEnded = true;
+
+      if (!isEnded) {
+        isEnded = true;
+        if (source && source.abort) source.abort(err);
+        if (sink) sink.end(err);
+      }
+    },
+    get paused() { return false; },
+    get ended() { return signalEnded; }
+  });
+
+  return stream;
+}
+
+export default takeUntil;