support Duration in Date.range/3

Author: tfiedlerdejanze

lib/elixir/lib/calendar/date.ex

@@ -100,7 +100,7 @@ defmodule Date do
 
   """
   @doc since: "1.5.0"
-  @spec range(Calendar.date(), Calendar.date()) :: Date.Range.t()
+  @spec range(Calendar.date(), Calendar.date() | Duration.t()) :: Date.Range.t()
   def range(%{calendar: calendar} = first, %{calendar: calendar} = last) do
     {first_days, _} = to_iso_days(first)
     {last_days, _} = to_iso_days(last)
@@ -119,6 +119,26 @@ defmodule Date do
     range(first, first_days, last, last_days, calendar, step)
   end
 
+  def range(%{calendar: calendar} = first, %Duration{} = duration) do
+    last = shift(first, duration)
+
+    {first_days, _} = to_iso_days(first)
+    {last_days, _} = to_iso_days(last)
+
+    step =
+      if first_days <= last_days do
+        1
+      else
+        IO.warn(
+          "a negative range was inferred for Date.range/2, call Date.range/3 instead with -1 as third argument"
+        )
+
+        -1
+      end
+
+    range(first, first_days, last, last_days, calendar, step)
+  end
+
   def range(%{calendar: _, year: _, month: _, day: _}, %{calendar: _, year: _, month: _, day: _}) do
     raise ArgumentError, "both dates must have matching calendars"
   end
@@ -140,7 +160,7 @@ defmodule Date do
 
   """
   @doc since: "1.12.0"
-  @spec range(Calendar.date(), Calendar.date(), step :: pos_integer | neg_integer) ::
+  @spec range(Calendar.date(), Calendar.date() | Duration.t(), step :: pos_integer | neg_integer) ::
           Date.Range.t()
   def range(%{calendar: calendar} = first, %{calendar: calendar} = last, step)
       when is_integer(step) and step != 0 do
@@ -149,6 +169,14 @@ defmodule Date do
     range(first, first_days, last, last_days, calendar, step)
   end
 
+  def range(%{calendar: calendar} = first, %Duration{} = duration, step) do
+    last = shift(first, duration)
+
+    {first_days, _} = to_iso_days(first)
+    {last_days, _} = to_iso_days(last)
+    range(first, first_days, last, last_days, calendar, step)
+  end
+
   def range(
         %{calendar: _, year: _, month: _, day: _} = first,
         %{calendar: _, year: _, month: _, day: _} = last,

lib/elixir/test/elixir/calendar/date_range_test.exs

@@ -6,8 +6,12 @@ defmodule Date.RangeTest do
 
   @asc_range Date.range(~D[2000-01-01], ~D[2001-01-01])
   @asc_range_2 Date.range(~D[2000-01-01], ~D[2001-01-01], 2)
+  @asc_range_duration Date.range(~D[2000-01-01], Duration.new!(year: 1))
+  @asc_range_duration_2 Date.range(~D[2000-01-01], Duration.new!(year: 1), 2)
   @desc_range Date.range(~D[2001-01-01], ~D[2000-01-01], -1)
   @desc_range_2 Date.range(~D[2001-01-01], ~D[2000-01-01], -2)
+  @desc_range_duration Date.range(~D[2001-01-01], Duration.new!(year: -1))
+  @desc_range_duration_2 Date.range(~D[2001-01-01], Duration.new!(year: -1), 2)
   @empty_range Date.range(~D[2001-01-01], ~D[2000-01-01], 1)
 
   describe "Enum.member?/2" do
@@ -20,6 +24,9 @@ defmodule Date.RangeTest do
 
       assert Enum.member?(@asc_range_2, ~D[2000-01-03])
       refute Enum.member?(@asc_range_2, ~D[2000-01-02])
+
+      assert Enum.member?(@asc_range_duration, ~D[2000-01-03])
+      refute Enum.member?(@asc_range_duration_2, ~D[2000-01-02])
     end
 
     test "for descending range" do
@@ -31,6 +38,9 @@ defmodule Date.RangeTest do
 
       assert Enum.member?(@desc_range_2, ~D[2000-12-30])
       refute Enum.member?(@desc_range_2, ~D[2000-12-29])
+
+      assert Enum.member?(@desc_range_duration, ~D[2000-12-30])
+      refute Enum.member?(@desc_range_duration_2, ~D[2000-12-29])
     end
 
     test "empty range" do
@@ -109,6 +119,18 @@ defmodule Date.RangeTest do
     assert Enum.to_list(range) == [~D[2000-01-01], ~D[2000-01-03]]
   end
 
+  test "works with durations" do
+    range = Date.range(~D[2000-01-01], Duration.new!(day: 1))
+    assert range.first == ~D[2000-01-01]
+    assert range.last == ~D[2000-01-02]
+    assert Enum.to_list(range) == [~D[2000-01-01], ~D[2000-01-02]]
+
+    range = Date.range(~D[2000-01-01], Duration.new!(day: 2), 2)
+    assert range.first == ~D[2000-01-01]
+    assert range.last == ~D[2000-01-03]
+    assert Enum.to_list(range) == [~D[2000-01-01], ~D[2000-01-03]]
+  end
+
   test "both dates must have matching calendars" do
     first = ~D[2000-01-01]
     last = Calendar.Holocene.date(12001, 1, 1)