Standard Libraries vs Tail-Recursion

al2o3cr · March 18, 2022, 6:00pm

Looks like String.downcase reassembles the string from individual codepoints:

lib/elixir/unicode/unicode.ex

18c44e2e4


      
          end
          
          def downcase(<<byte, rest::bits>>, acc, mode) do
            if byte >= ?A and byte <= ?Z do
              downcase(rest, [byte + 32 | acc], mode)
            else
              downcase(rest, [byte | acc], mode)
            end
          end
          
          def downcase("", acc, _mode), do: IO.iodata_to_binary(:lists.reverse(acc))
          
          # Sigma handling
          
          defp cased_letter_binary?(<<codepoint::utf8, rest::bits>>) do
            if case_ignorable?(codepoint) do
              cased_letter_binary?(rest)
            else
              cased_letter?(codepoint)
            end
          end

That should lose any reference to the original un-split binary, right?