implement string sigil rewrites

README.md

@@ -80,6 +80,7 @@ Disabling the rules means updating your `.credo.exs` depending on your configura
 {Credo.Check.Readability.SinglePipe, false},
 # **potentially breaks compilation** - see **Troubleshooting** section below
 {Credo.Check.Readability.StrictModuleLayout, false},
+{Credo.Check.Readability.StringSigils, false},
 {Credo.Check.Readability.UnnecessaryAliasExpansion, false},
 {Credo.Check.Readability.WithSingleClause, false},
 {Credo.Check.Refactor.CaseTrivialMatches, false},

lib/style/single_node.ex

@@ -18,6 +18,7 @@ defmodule Styler.Style.SingleNode do
   * Credo.Check.Readability.LargeNumbers
   * Credo.Check.Readability.ParenthesesOnZeroArityDefs
   * Credo.Check.Readability.PreferImplicitTry
+  * Credo.Check.Readability.StringSigils
   * Credo.Check.Readability.WithSingleClause
   * Credo.Check.Refactor.CaseTrivialMatches
   * Credo.Check.Refactor.CondStatements
@@ -29,15 +30,52 @@ defmodule Styler.Style.SingleNode do
 
   alias Styler.Zipper
 
+
+
   def run({node, meta}, ctx), do: {:cont, {style(node), meta}, ctx}
 
   # as of 1.15, elixir's formatter takes care of this for us.
   if Version.match?(System.version(), "< 1.15.0-dev") do
     # 'charlist' => ~c"charlist"
-    defp style({:__block__, meta, [chars]} = node) when is_list(chars) do
-      if meta[:delimiter] == "'",
-        do: {:sigil_c, Keyword.put(meta, :delimiter, "\""), [{:<<>>, [line: meta[:line]], [List.to_string(chars)]}, []]},
-        else: node
+    defp style({:__block__, [{:delimiter, ~s|"|} | meta], [chars]} = node) when is_list(chars),
+      do: {:sigil_c, [{:delimiter, ~s|"|} | meta], [{:<<>>, [line: meta[:line]], [List.to_string(chars)]}, []]}
+  end
+
+  defp style({:__block__, [{:delimiter, ~s|"|} | meta], [string]} = node) when is_binary(string) do
+    # @TODO this'll run a regex against every double-quote delimited string in the codebase.
+    # is there a faster way to do this? is it too expensive vis-a-vis styler's goal of speed?
+    if string =~ ~r/".*".*".*"/ do
+      frequencies =
+        string
+        |> String.codepoints()
+        |> Stream.filter(& &1 in [")", "]", "}", "|", ">", ~s|"|])
+        |> Enum.frequencies()
+
+      # choose whichever delimiter has the least occurences, ties being broken by delimiter_priority
+      {closer, _} =
+        %{~s|"| => 0, ")" => 0, "]" => 0, "}" => 0, "|" => 0, ">" => 0}
+        |> Map.merge(frequencies)
+        |> Enum.min_by(fn
+          {~s|"|, count} -> {count, 0}
+          {")", count} -> {count, 1}
+          {"]", count} -> {count, 2}
+          {"}", count} -> {count, 3}
+          {"|", count} -> {count, 4}
+          {">", count} -> {count, 5}
+        end)
+
+      delimiter =
+        case closer do
+          ")" -> "("
+          "]" -> "["
+          "}" -> "{"
+          ">" -> "<"
+          x -> x
+        end
+
+      {:sigil_s, [{:delimiter, delimiter} | meta], [{:<<>>, [line: meta[:line]], [string]}, []]}
+    else
+      node
     end
   end