WIP: allow user to be able to control the parse state.

lib/nimble_csv.ex

@@ -338,8 +338,16 @@ defmodule NimbleCSV do
 
         Stream.transform(
           stream,
-          fn -> state end,
-          &parse(maybe_to_utf8(&1), &2, separator, escape),
+          fn -> {0, state} end,
+          &to_enum(parse(maybe_to_utf8(&1), &2, separator, escape),
+            &2,
+            fn {count, parse_state}, kind -> do
+              case kind do
+                :line -> {count + 1, :line}
+                :header -> {count, :line}
+              end
+            end
+          ),
           &finalize_parser/1
         )
       end
@@ -351,7 +359,15 @@ defmodule NimbleCSV do
           Enum.flat_map_reduce(
             enumerable,
             state,
-            &parse(maybe_to_utf8(&1), &2, separator, escape)
+            &to_enum(parse(maybe_to_utf8(&1), &2, separator, escape),
+              &2,
+              fn {count, parse_state}, kind -> do
+                  case kind do
+                    :line -> {count + 1, :line}
+                    :header -> {count, :line}
+                  end
+                end
+            )
           )
 
         finalize_parser(state)
@@ -442,20 +458,20 @@ defmodule NimbleCSV do
         :ok
       end
 
-      defp to_enum(result) do
+      defp to_enum(result, state, fstate) do
         case result do
-          {:line, row} -> {[row], :line}
-          {:header, _} -> {[], :line}
+          {:line, row} -> {[row], fstate(state, :line)}
+          {:header, _} -> {[], fstate(state, :header)}
           {:escape, _, _, _} = escape -> {[], escape}
         end
       end
 
       defp parse(line, {:escape, entry, row, state}, separator, escape) do
-        to_enum(escape(line, entry, row, state, separator, escape))
+        escape(line, entry, row, state, separator, escape)
       end
 
       defp parse(line, state, separator, escape) do
-        to_enum(separator(line, [], state, separator, escape))
+        separator(line, [], state, separator, escape)
       end
 
       defmacrop newlines_separator!() do