1 files changed, 42 insertions, 0 deletions
diff --git a/vere/pkg/noun/jets/d/by_key.c b/vere/pkg/noun/jets/d/by_key.c
new file mode 100644
index 0000000..b4f8a09
--- /dev/null
+++ b/vere/pkg/noun/jets/d/by_key.c
@@ -0,0 +1,42 @@
+/// @file
+
+#include "jets/q.h"
+#include "jets/w.h"
+
+#include "noun.h"
+
+//  [a] is RETAINED, [set] is TRANSFERRED
+//
+static u3_noun
+_by_key(u3_noun a, u3_noun set)
+{
+  if ( u3_nul == a ) {
+    return set;
+  }
+  else {
+    u3_noun n_a, l_a, r_a;
+    u3x_trel(a, &n_a, &l_a, &r_a);
+
+    {
+      u3_noun new = u3qdi_put(set, u3h(n_a));
+      u3z(set);
+      set = new;
+    }
+
+    set = _by_key(l_a, set);
+
+    return _by_key(r_a, set);
+  }
+}
+
+u3_noun
+u3qdb_key(u3_noun a)
+{
+  return _by_key(a, u3_nul);
+}
+
+u3_noun
+u3wdb_key(u3_noun cor)
+{
+  return u3qdb_key(u3x_at(u3x_con_sam, cor));
+}