Improve ISO8601 offset parsing

Author: José Valim

lib/elixir/lib/calendar.ex

@@ -171,8 +171,7 @@ defmodule Date do
   As specified in the standard, the separator "T" may be omitted if
   desired as there is no ambiguity within this function.
 
-  Time representations with reduced accuracy and decimal fractions
-  are not supported.
+  Time representations with reduced accuracy are not supported.
 
   ## Examples
 
@@ -418,8 +417,7 @@ defmodule Time do
   As specified in the standard, the separator "T" may be omitted if
   desired as there is no ambiguity within this function.
 
-  Time representations with reduced accuracy and decimal fractions
-  are not supported.
+  Time representations with reduced accuracy are not supported.
 
   ## Examples
 
@@ -736,8 +734,7 @@ defmodule NaiveDateTime do
   As specified in the standard, the separator "T" may be omitted if
   desired as there is no ambiguity within this function.
 
-  Time representations with reduced accuracy and decimal fractions
-  are not supported.
+  Time representations with reduced accuracy are not supported.
 
   ## Examples
 
@@ -766,6 +763,19 @@ defmodule NaiveDateTime do
       iex> NaiveDateTime.from_iso8601("2015-01-32 23:50:07")
       {:error, :invalid_date}
 
+      iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123+02:30")
+      {:ok, ~N[2015-01-23 23:50:07.123]}
+      iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123+00:00")
+      {:ok, ~N[2015-01-23 23:50:07.123]}
+      iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-02:30")
+      {:ok, ~N[2015-01-23 23:50:07.123]}
+      iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-00:00")
+      {:error, :invalid_format}
+      iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-00:60")
+      {:error, :invalid_format}
+      iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-24:00")
+      {:error, :invalid_format}
+
   """
   @spec from_iso8601(String.t) :: {:ok, NaiveDateTime.t} | {:error, atom}
   def from_iso8601(<<year::4-bytes, ?-, month::2-bytes, ?-, day::2-bytes, sep,

lib/elixir/lib/calendar/iso.ex

@@ -165,7 +165,25 @@ defmodule Calendar.ISO do
     do: {acc, precision, rest}
 
   @doc false
-  def parse_offset("Z"), do: {0, ""}
-  def parse_offset(""),  do: {nil, ""}
-  def parse_offset(_),   do: :error
+  def parse_offset(""),
+    do: {nil, ""}
+  def parse_offset("Z"),
+    do: {0, ""}
+  def parse_offset("-00:00"),
+    do: :error
+  def parse_offset(<<?+, hour::2-bytes, ?:, min::2-bytes, rest::binary>>),
+    do: parse_offset(1, hour, min, rest)
+  def parse_offset(<<?-, hour::2-bytes, ?:, min::2-bytes, rest::binary>>),
+    do: parse_offset(-1, hour, min, rest)
+  def parse_offset(_),
+    do: :error
+
+  defp parse_offset(sign, hour, min, rest) do
+    with {hour, ""} when hour < 24 <- Integer.parse(hour),
+         {min, ""} when min < 60 <- Integer.parse(min) do
+      {((hour * 60) + min) * 60 * sign, rest}
+    else
+      _ -> :error
+    end
+  end
 end