be more safe with line splitting

Author: lukaszsamson

apps/debug_adapter/lib/debug_adapter/server.ex

@@ -1471,7 +1471,7 @@ defmodule ElixirLS.DebugAdapter.Server do
       line =
         text
         |> String.split(["\r\n", "\n", "\r"])
-        |> Enum.at(line)
+        |> Enum.at(line, "")
 
       # It is measured in UTF-16 code units and the client capability
       # `columnsStartAt1` determines whether it is 0- or 1-based.

apps/language_server/lib/language_server/providers/code_lens/test.ex

@@ -92,7 +92,7 @@ defmodule ElixirLS.LanguageServer.Providers.CodeLens.Test do
 
       test_name =
         source_lines
-        |> Enum.at(line - 1)
+        |> Enum.at(line - 1, "")
         |> String.trim()
         |> case do
           "test " <> rest ->

apps/language_server/lib/language_server/providers/code_lens/test/describe_block.ex

@@ -30,7 +30,7 @@ defmodule ElixirLS.LanguageServer.Providers.CodeLens.Test.DescribeBlock do
   defp get_name(source_lines, declaration_line) do
     case Regex.named_captures(
            ~r/^\s*describe "(?<name>.*)" do/u,
-           Enum.at(source_lines, declaration_line - 1)
+           Enum.at(source_lines, declaration_line - 1, "")
          ) do
       %{"name" => name} ->
         name

apps/language_server/lib/language_server/providers/completion.ex

@@ -126,7 +126,7 @@ defmodule ElixirLS.LanguageServer.Providers.Completion do
         options
       ) do
     lines = SourceFile.lines(text)
-    line_text = Enum.at(lines, line - 1)
+    line_text = Enum.at(lines, line - 1, "")
 
     text_before_cursor = String.slice(line_text, 0, character - 1)
     text_after_cursor = String.slice(line_text, (character - 1)..-1//1)
@@ -187,7 +187,7 @@ defmodule ElixirLS.LanguageServer.Providers.Completion do
               {_, meta, _} when is_list(meta) ->
                 if Keyword.has_key?(meta, :do) do
                   line = Keyword.fetch!(meta, :line)
-                  line_text = Enum.at(lines, line - 1)
+                  line_text = Enum.at(lines, line - 1, "")
                   String.length(line_text) - String.length(String.trim_leading(line_text))
                 end
 

apps/language_server/lib/language_server/providers/document_symbols.ex

@@ -508,7 +508,7 @@ defmodule ElixirLS.LanguageServer.Providers.DocumentSymbols do
           if parent_end_line > parent_do_line do
             # take end location from parent and assume end_of_expression is last char in previous line
             end_of_expression =
-              (Enum.at(lines, max(parent_end_line - 2, 0)) || "")
+              Enum.at(lines, max(parent_end_line - 2, 0), "")
               |> String.length()
 
             SourceFile.elixir_position_to_lsp(
@@ -517,7 +517,7 @@ defmodule ElixirLS.LanguageServer.Providers.DocumentSymbols do
             )
           else
             # take end location from parent and assume end_of_expression is last char before final ; trimmed
-            line = Enum.at(lines, parent_end_line - 1)
+            line = Enum.at(lines, parent_end_line - 1, "")
             parent_end_column = location[:parent_location][:end][:column]
 
             end_of_expression =

apps/language_server/lib/language_server/providers/execute_command/apply_spec.ex

@@ -48,7 +48,7 @@ defmodule ElixirLS.LanguageServer.Providers.ExecuteCommand.ApplySpec do
       end
 
     if line do
-      cur_line = Enum.at(SourceFile.lines(cur_text), line - 1)
+      cur_line = Enum.at(SourceFile.lines(cur_text), line - 1, "")
       [indentation] = Regex.run(~r/^\s*/u, cur_line)
 
       # Attempt to format to fit within the preferred line length, fallback to having it all on one

apps/language_server/lib/language_server/providers/hover.ex

@@ -32,9 +32,9 @@ defmodule ElixirLS.LanguageServer.Providers.Hover do
   def build_range(lines, %{begin: {begin_line, begin_char}, end: {end_line, end_char}}) do
     range(
       begin_line - 1,
-      SourceFile.elixir_character_to_lsp(lines |> Enum.at(begin_line - 1), begin_char),
+      SourceFile.elixir_character_to_lsp(lines |> Enum.at(begin_line - 1, ""), begin_char),
       end_line - 1,
-      SourceFile.elixir_character_to_lsp(lines |> Enum.at(end_line - 1), end_char)
+      SourceFile.elixir_character_to_lsp(lines |> Enum.at(end_line - 1, ""), end_char)
     )
   end
 

apps/language_server/lib/language_server/providers/on_type_formatting.ex

@@ -36,7 +36,7 @@ defmodule ElixirLS.LanguageServer.Providers.OnTypeFormatting do
         end
 
       # Apply the proposed change to the current text so we can see if it fixes terminators
-      insert_on_next_line? = blank?(Enum.at(lines, line)) and line != Enum.count(lines) - 1
+      insert_on_next_line? = blank?(Enum.at(lines, line, "")) and line != Enum.count(lines) - 1
       {range, new_text} = insert_end_edit(prev_indentation, line, character, insert_on_next_line?)
       edited_text = SourceFile.apply_edit(source_file.text, range, new_text)
 

apps/language_server/lib/language_server/providers/selection_ranges.ex

@@ -157,7 +157,7 @@ defmodule ElixirLS.LanguageServer.Providers.SelectionRanges do
             # ^ 
             [outer_range | acc]
           else
-            line_length = lines |> Enum.at(end_line - 1) |> String.length()
+            line_length = lines |> Enum.at(end_line - 1, "") |> String.length()
             inner_range = range(start_line + 1, 0, end_line - 1, line_length)
 
             find_stop_token_range(stop_tokens_in_pair, pair, inner_range, line, character) ++
@@ -262,8 +262,8 @@ defmodule ElixirLS.LanguageServer.Providers.SelectionRanges do
           cell_pairs,
         (start_line < line or (start_line == line and start_character <= character)) and
           end_line > line do
-      line_length = lines |> Enum.at(end_line - 1) |> String.length()
-      second_line = lines |> Enum.at(start_line + 1)
+      line_length = lines |> Enum.at(end_line - 1, "") |> String.length()
+      second_line = lines |> Enum.at(start_line + 1, "")
 
       second_line_indent =
         String.length(second_line) - String.length(String.trim_leading(second_line))
@@ -308,19 +308,19 @@ defmodule ElixirLS.LanguageServer.Providers.SelectionRanges do
           (end_line > line or (end_line == line and end_line_start_character <= character)) do
       case group do
         [_] ->
-          line_length = lines |> Enum.at(start_line) |> String.length()
+          line_length = lines |> Enum.at(start_line, "") |> String.length()
           full_line_range = range(start_line, 0, start_line, line_length)
           [full_line_range, range(start_line, start_character, start_line, line_length)]
 
         _ ->
-          end_line_length = lines |> Enum.at(end_line) |> String.length()
+          end_line_length = lines |> Enum.at(end_line, "") |> String.length()
           full_block_full_line_range = range(start_line, 0, end_line, end_line_length)
           full_block_range = range(start_line, start_character, end_line, end_line_length)
 
           [full_block_full_line_range, full_block_range] ++
             Enum.find_value(group, fn {{cursor_line, cursor_line_character}, _} ->
               if cursor_line == line do
-                cursor_line_length = lines |> Enum.at(cursor_line) |> String.length()
+                cursor_line_length = lines |> Enum.at(cursor_line, "") |> String.length()
 
                 line_range =
                   range(