Deprecate RawParseUtils.parse_base_10/1 in favor of ParseDecimal.from…

…_decimal_charlist/1. (#195)

lib/xgit/core/object.ex

@@ -58,6 +58,7 @@ defmodule Xgit.Core.Object do
   alias Xgit.Core.FileMode
   alias Xgit.Core.FilePath
   alias Xgit.Core.ObjectId
+  alias Xgit.Util.ParseDecimal
   alias Xgit.Util.RawParseUtils
 
   import Xgit.Util.ForceCoverage
@@ -407,8 +408,10 @@ defmodule Xgit.Core.Object do
            {:missing_email, RawParseUtils.next_lf(data, ?<)},
          {:bad_email, [?> | after_email]} <- {:bad_email, RawParseUtils.next_lf(email_start, ?>)},
          {:missing_space_before_date, [?\s | date]} <- {:missing_space_before_date, after_email},
-         {:bad_date, {_date, [?\s | tz]}} <- {:bad_date, RawParseUtils.parse_base_10(date)},
-         {:bad_timezone, {_tz, [?\n | next]}} <- {:bad_timezone, RawParseUtils.parse_base_10(tz)} do
+         {:bad_date, {_date, [?\s | tz]}} <-
+           {:bad_date, ParseDecimal.from_decimal_charlist(date)},
+         {:bad_timezone, {_tz, [?\n | next]}} <-
+           {:bad_timezone, ParseDecimal.from_decimal_charlist(tz)} do
       next
     else
       {:missing_email, _} -> cover :missing_email

lib/xgit/core/person_ident.ex

@@ -51,10 +51,11 @@ defmodule Xgit.Core.PersonIdent do
   A combination of a person identity and time in git.
   """
 
-  import Xgit.Util.ForceCoverage
-
+  alias Xgit.Util.ParseDecimal
   alias Xgit.Util.RawParseUtils
 
+  import Xgit.Util.ForceCoverage
+
   @typedoc "Time zone offset in minutes +/- from GMT."
   @type tz_offset :: -720..840
 
@@ -144,7 +145,7 @@ defmodule Xgit.Core.PersonIdent do
 
     case {time, tz} do
       {[_ | _], [_ | _]} ->
-        {time |> RawParseUtils.parse_base_10() |> elem(0),
+        {time |> ParseDecimal.from_decimal_charlist() |> elem(0),
          tz |> RawParseUtils.parse_timezone_offset() |> elem(0)}
 
       _ ->

lib/xgit/repository/on_disk/get_object.ex

@@ -6,7 +6,7 @@ defmodule Xgit.Repository.OnDisk.GetObject do
 
   alias Xgit.Core.Object
   alias Xgit.Core.ObjectId
-  alias Xgit.Util.RawParseUtils
+  alias Xgit.Util.ParseDecimal
   alias Xgit.Util.UnzipStream
 
   defmodule LooseObjectContentSource do
@@ -93,7 +93,7 @@ defmodule Xgit.Repository.OnDisk.GetObject do
   defp parse_length(_type, ' '), do: cover(:invalid_header)
 
   defp parse_length(type, [?\s | length]) do
-    case RawParseUtils.parse_base_10(length) do
+    case ParseDecimal.from_decimal_charlist(length) do
       {length, []} when is_integer(length) and length >= 0 -> {:header, type, length}
       _ -> cover :invalid_header
     end

lib/xgit/util/parse_decimal.ex

@@ -0,0 +1,39 @@
+defmodule Xgit.Util.ParseDecimal do
+  @moduledoc false
+  # Internal utility for parsing decimal values from charlist.
+
+  import Xgit.Util.ForceCoverage
+
+  @doc ~S"""
+  Parse a base-10 numeric value from a charlist of ASCII digits into a number.
+
+  Similar to `Integer.parse/2` but uses charlist instead.
+
+  Digit sequences can begin with an optional run of spaces before the
+  sequence, and may start with a `+` or a `-` to indicate sign position.
+  Any other characters will cause the method to stop and return the current
+  result to the caller.
+
+  Returns `{number, new_buffer}` where `number` is the integer that was
+  found (or 0 if no number found there) and `new_buffer` is the charlist
+  following the number that was parsed.
+  """
+  @spec from_decimal_charlist(b :: charlist) :: {integer, charlist}
+  def from_decimal_charlist(b) when is_list(b) do
+    b = skip_white_space(b)
+    {sign, b} = parse_sign(b)
+    {n, b} = parse_digits(0, b)
+
+    cover {sign * n, b}
+  end
+
+  defp skip_white_space([?\s | b]), do: skip_white_space(b)
+  defp skip_white_space(b), do: b
+
+  defp parse_sign([?- | b]), do: cover({-1, b})
+  defp parse_sign([?+ | b]), do: cover({1, b})
+  defp parse_sign(b), do: cover({1, b})
+
+  defp parse_digits(n, [d | b]) when d >= ?0 and d <= ?9, do: parse_digits(n * 10 + (d - ?0), b)
+  defp parse_digits(n, b), do: cover({n, b})
+end

test/xgit/util/parse_decimal_test.exs

@@ -0,0 +1,14 @@
+defmodule Xgit.Util.ParseDecimalTest do
+  use ExUnit.Case, async: true
+
+  import Xgit.Util.ParseDecimal
+
+  test "from_decimal_charlist/1" do
+    assert from_decimal_charlist('abc') == {0, 'abc'}
+    assert from_decimal_charlist('0abc') == {0, 'abc'}
+    assert from_decimal_charlist('99') == {99, ''}
+    assert from_decimal_charlist('+99x') == {99, 'x'}
+    assert from_decimal_charlist('  -42 ') == {-42, ' '}
+    assert from_decimal_charlist('   xyz') == {0, 'xyz'}
+  end
+end