1 files changed, 32 insertions, 0 deletions
diff --git a/Sources/NorgUI/Helpers/Ordinals.swift b/Sources/NorgUI/Helpers/Ordinals.swift
new file mode 100644
index 0000000..649c3e0
--- /dev/null
+++ b/Sources/NorgUI/Helpers/Ordinals.swift
@@ -0,0 +1,32 @@
+import NorgKit
+
+/// Assigns sequential numbers to ordered list items.
+func orderedOrdinals(_ blocks: [NorgBlock]) -> [Int?] {
+  var counters: [Int: Int] = [:]
+  return blocks.map { block in
+    switch block {
+    case .orderedListItem(let level, _, _, _):
+      counters = counters.filter { $0.key <= level }
+      counters[level, default: 0] += 1
+      return counters[level]
+    case .unorderedListItem(let level, _, _, _):
+      counters = counters.filter { $0.key < level }
+      return nil
+    default:
+      counters.removeAll()
+      return nil
+    }
+  }
+}
+
+/// Numbers the ordered list items within a single tree branch.
+func ordinals(forSiblings nodes: [NorgNode]) -> [Int?] {
+  var counter = 0
+  return nodes.map { node in
+    if case .orderedListItem = node.block {
+      counter += 1
+      return counter
+    }
+    return nil
+  }
+}