Fix handling of columns and indentation (#183)

Author: doorgan

lib/sourceror.ex

@@ -123,7 +123,9 @@ defmodule Sourceror do
   """
   @spec parse_string(String.t(), Keyword.t()) :: {:ok, Macro.t()} | {:error, term()}
   def parse_string(source, opts \\ []) do
-    opts = Keyword.take(opts, [:line, :column])
+    opts = Keyword.take(opts, [:line, :column, :indentation])
+
+    {source, opts} = maybe_apply_columns_fix(source, opts)
 
     with {:ok, quoted, comments} <- string_to_quoted(source, opts ++ to_quoted_opts()) do
       {:ok, Sourceror.Comments.merge_comments(quoted, comments)}
@@ -135,12 +137,55 @@ defmodule Sourceror do
   """
   @spec parse_string!(String.t()) :: Macro.t()
   def parse_string!(source, opts \\ []) do
-    opts = Keyword.take(opts, [:line, :column])
+    opts = Keyword.take(opts, [:line, :column, :indentation])
+
+    {source, opts} = maybe_apply_columns_fix(source, opts)
 
     {quoted, comments} = string_to_quoted!(source, opts ++ to_quoted_opts())
     Sourceror.Comments.merge_comments(quoted, comments)
   end
 
+  cond do
+    Version.match?(System.version(), ">= 1.16.0 and < 1.19.0") ->
+      defp maybe_apply_columns_fix(source, opts) do
+        {source, opts} =
+          case Keyword.get(opts, :column) do
+            start_column when is_integer(start_column) ->
+              source = String.duplicate(" ", start_column - 1) <> source
+              opts = Keyword.delete(opts, :column)
+              {source, opts}
+
+            _ ->
+              {source, opts}
+          end
+
+        apply_indentation_fix(source, opts)
+      end
+
+    Version.match?(System.version(), "< 1.19.0") ->
+      defp maybe_apply_columns_fix(source, opts) do
+        apply_indentation_fix(source, opts)
+      end
+
+    true ->
+      defp maybe_apply_columns_fix(source, opts) do
+        {source, opts}
+      end
+  end
+
+  defp apply_indentation_fix(source, opts) do
+    case Keyword.get(opts, :indentation) do
+      indentation when is_integer(indentation) ->
+        opts = Keyword.delete(opts, :indentation)
+        source = indent(source, " ", indentation - 1)
+
+        {source, opts}
+
+      _ ->
+        {source, opts}
+    end
+  end
+
   defp to_quoted_opts do
     [
       literal_encoder: &{:ok, {:__block__, &2, [&1]}},

test/sourceror_test.exs

@@ -336,6 +336,55 @@ defmodule SourcerorTest do
       assert {:hello, meta, _} = Sourceror.parse_string!(string, column: 42)
       assert meta[:column] == 42
     end
+
+    test "the column is reset after the first line" do
+      string = ~S"""
+      foo do
+        bar
+      end
+      """
+
+      assert {:foo, foo_meta,
+              [
+                [{{:__block__, _, [:do]}, {:bar, bar_meta, _}}]
+              ]} = Sourceror.parse_string!(string, column: 10)
+
+      assert foo_meta[:column] == 10
+      # Would be 13 if it didn't reset
+      assert bar_meta[:column] == 3
+    end
+
+    test "allows setting the indentation" do
+      string = ~S"""
+      foo do
+        bar
+      end
+      """
+
+      assert {:foo, foo_meta,
+              [
+                [{{:__block__, _, [:do]}, {:bar, bar_meta, _}}]
+              ]} = Sourceror.parse_string!(string, indentation: 5)
+
+      assert foo_meta[:column] == 5
+      assert bar_meta[:column] == 7
+    end
+
+    test "allows setting both column and indentation" do
+      string = ~S"""
+      foo do
+        bar
+      end
+      """
+
+      assert {:foo, foo_meta,
+              [
+                [{{:__block__, _, [:do]}, {:bar, bar_meta, _}}]
+              ]} = Sourceror.parse_string!(string, column: 10, indentation: 5)
+
+      assert foo_meta[:column] == 14
+      assert bar_meta[:column] == 7
+    end
   end
 
   describe "parse_expression/2" do