Stop get_by_id traversal on first match (#572)

lib/floki.ex

@@ -308,12 +308,7 @@ defmodule Floki do
 
   """
   @spec get_by_id(html_tree() | html_node(), String.t()) :: html_node() | nil
-  def get_by_id(html_tree_as_tuple, id)
-      when is_list(html_tree_as_tuple) or is_html_node(html_tree_as_tuple) do
-    html_tree_as_tuple
-    |> Finder.find(%Floki.Selector{id: id})
-    |> List.first()
-  end
+  defdelegate get_by_id(html_tree_as_tuple, id), to: Finder, as: :find_by_id
 
   @doc """
   Changes the attribute values of the elements matched by `selector`

lib/floki/finder.ex

@@ -9,6 +9,28 @@ defmodule Floki.Finder do
   alias Selector.PseudoClass
   import Floki, only: [is_html_node: 1]
 
+  @spec find_by_id(Floki.html_tree() | Floki.html_node(), String.t()) :: Floki.html_node() | nil
+  def find_by_id(html_tree_as_tuple, id) do
+    html_tree_as_tuple = List.wrap(html_tree_as_tuple)
+    traverse_find_by_id(html_tree_as_tuple, id)
+  end
+
+  defp traverse_find_by_id([{_type, _attributes, children} = html_tuple | rest], id) do
+    if Selector.id_match?(html_tuple, id) do
+      html_tuple
+    else
+      traverse_find_by_id(children, id) || traverse_find_by_id(rest, id)
+    end
+  end
+
+  defp traverse_find_by_id([_ | rest], id) do
+    traverse_find_by_id(rest, id)
+  end
+
+  defp traverse_find_by_id([], _id) do
+    nil
+  end
+
   # Find elements inside a HTML tree.
   # Second argument can be either a selector string, a selector struct or a list of selector structs.
 

lib/floki/selector.ex

@@ -99,8 +99,8 @@ defmodule Floki.Selector do
 
   defp can_match_combinator?(_node, _combinator), do: true
 
-  defp id_match?(_node, nil), do: true
-  defp id_match?(node, id), do: attribute_value(node, "id") == id
+  def id_match?(_node, nil), do: true
+  def id_match?(node, id), do: attribute_value(node, "id") == id
 
   defp namespace_match?(_node, namespace) when is_wildcard(namespace), do: true