first version of outline

lib/chiya_web/outline.ex

@@ -3,19 +3,39 @@ defmodule ChiyaWeb.Outline do
   @heading_regex ~r/^(#+)\s(.+)$/
 
   def get(markdown) do
-    headings =
-      @outline_regex
-      |> Regex.scan(markdown, capture: :all)
-
-    Enum.chunk_by(headings, fn h -> nil end)
-  end
-
-  def level(heading) do
-    Regex.scan(@heading_regex, heading)
-    |> Enum.map(fn [_, level, heading] ->
-      [level_from_string(level), heading]
-    end)
+    @outline_regex
+    |> Regex.scan(markdown, capture: :all)
+    |> List.flatten()
+    |> Enum.map(&into_map/1)
+    |> into_tree([])
   end
 
   defp level_from_string(string), do: String.length(string)
+
+  defp into_map(heading) do
+    [[_, level, heading]] = Regex.scan(@heading_regex, heading)
+    %{level: level_from_string(level), text: heading, children: []}
+  end
+
+  defp into_tree([], result), do: result
+
+  defp into_tree([head | tail], result) do
+    level = head.level
+
+    # Split the remaining items (tail) at the next
+    # same level element as the current (head)
+    # The first list will be the children of the head,
+    # the second list will be the new list
+    {children, new_list} =
+      Enum.split_while(tail, fn heading ->
+        level < heading.level
+      end)
+
+    # add the children to the current item
+    head = Map.put(head, :children, children)
+
+    # call again with new list and current item 
+    # added to result
+    into_tree(new_list, result ++ [head])
+  end
 end

test/chiya_web/outline_test.exs

@@ -5,16 +5,32 @@ defmodule ChiyaWeb.OutlineTest do
 
   describe "extract_outline/1" do
     test "extracts headlines from markdown" do
-      markdown = "# Heading\nsome paragraph\n## Sub Heading\n# Second Heading"
+      markdown =
+        "# Heading\nsome paragraph\n## Sub Heading\nsome text\n## Second Sub Heading\nmore text\n# Second Heading"
 
-      assert [{1, "Heading", [{2, "Sub Heading", []}]}, {1, "Second Heading", []}] =
-               Outline.get(markdown)
+      result = [
+        %{
+          level: 1,
+          text: "Heading",
+          children: [
+            %{level: 2, text: "Sub Heading", children: []},
+            %{level: 2, text: "Second Sub Heading", children: []}
+          ]
+        },
+        %{level: 1, text: "Second Heading", children: []}
+      ]
+
+      assert result == Outline.get(markdown)
     end
   end
 
-  describe "outline_level/1" do
-    test "extracts outline level" do
-      assert {1, "Heading"} = Outline.level("# Heading")
-    end
+  test "extracts headlines from markdown 2" do
+    markdown = "## Second Level"
+
+    result = [
+      %{level: 2, text: "Second Level", children: []}
+    ]
+
+    assert result == Outline.get(markdown)
   end
 end