Merge branch 'main' into wm-document-encoder

Author: wojtekmach

lib/decimal.ex

@@ -1360,6 +1360,12 @@ defmodule Decimal do
       iex> Decimal.new("3.14")
       Decimal.new("3.14")
 
+      iex> Decimal.new("1.79769313486231581e308")
+      Decimal.new("1.79769313486231581e308")
+
+      iex> Decimal.new("2.22507385850720139e-308")
+      Decimal.new("2.22507385850720139e-308")
+
   """
   @spec new(decimal) :: t
   def new(%Decimal{sign: sign, coef: coef, exp: exp} = num)
@@ -1664,13 +1670,28 @@ defmodule Decimal do
 
       iex> Decimal.to_float(Decimal.new("1.5"))
       1.5
+      iex> Decimal.to_float(Decimal.new("-1.79769313486231581e308"))
+      ** (Decimal.Error) : negative number smaller than DBL_MAX: Decimal.new("-1.79769313486231581E+308")
+
+
+      iex> Decimal.to_float(Decimal.new("-1.79769313486231581e308"))
+      ** (Decimal.Error) : negative number smaller than DBL_MAX: Decimal.new("-1.79769313486231581E+308")
+
+
+      iex> Decimal.to_float(Decimal.new("2.22507385850720139e-308"))
+      ** (Decimal.Error) : number smaller than DBL_MIN: Decimal.new("2.22507385850720139E-308")
+
+
+      iex> Decimal.to_float(Decimal.new("-2.22507385850720139e-308"))
+      ** (Decimal.Error): negative number bigger than DBL_MIN: Decimal.new(\"-2.22507385850720139E-308\")
 
       iex> Decimal.to_float(Decimal.new("inf"))
       ** (ArgumentError) Infinity cannot be converted to float
 
   """
   @spec to_float(t) :: float
-  def to_float(%Decimal{sign: sign, coef: coef, exp: exp}) when is_integer(coef) do
+  def to_float(%Decimal{coef: coef} = decimal) when is_integer(coef) do
+    %Decimal{sign: sign, coef: coef, exp: exp} = check_dbl_min_max(decimal)
     # Convert back to float without loss
     # http://www.exploringbinary.com/correct-decimal-to-floating-point-using-big-integers/
     {num, den} = ratio(coef, exp)
@@ -2059,15 +2080,15 @@ defmodule Decimal do
   defp parse_float("." <> rest), do: parse_digits(rest)
   defp parse_float(bin), do: {[], bin}
 
-  defp parse_exp(<<e, rest::binary>>) when e in [?e, ?E] do
-    case rest do
-      <<sign, rest::binary>> when sign in [?+, ?-] ->
-        {digits, rest} = parse_digits(rest)
-        {[sign | digits], rest}
+  defp parse_exp(<<e, sign, digit, rest::binary>>)
+       when e in [?e, ?E] and sign in [?+, ?-] and digit in ?0..?9 do
+    {digits, rest} = parse_digits(rest)
+    {[sign, digit | digits], rest}
+  end
 
-      _ ->
-        parse_digits(rest)
-    end
+  defp parse_exp(<<e, digit, rest::binary>>) when e in [?e, ?E] and digit in ?0..?9 do
+    {digits, rest} = parse_digits(rest)
+    {[digit | digits], rest}
   end
 
   defp parse_exp(bin) do
@@ -2125,6 +2146,38 @@ defmodule Decimal do
 
   defp fix_float_exp([], result), do: :lists.reverse(result)
 
+  defp check_dbl_min_max(%Decimal{coef: :inf} = infinity), do: infinity
+
+  defp check_dbl_min_max(%Decimal{sign: 1} = num) do
+    cond do
+      Decimal.gt?(num, dbl_max(1)) ->
+        raise Error, reason: "number bigger than DBL_MAX: #{inspect(num)}"
+
+      Decimal.gt?(num, zero(1)) and Decimal.lt?(num, dbl_min(1)) ->
+        raise Error, reason: "number smaller than DBL_MIN: #{inspect(num)}"
+
+      true ->
+        num
+    end
+  end
+
+  defp check_dbl_min_max(num) do
+    cond do
+      Decimal.lt?(num, dbl_max(-1)) ->
+        raise Error, reason: "negative number smaller than DBL_MAX: #{inspect(num)}"
+
+      Decimal.lt?(num, zero(-1)) and Decimal.gt?(num, dbl_min(-1)) ->
+        raise Error, reason: "negative number bigger than DBL_MIN: #{inspect(num)}"
+
+      true ->
+        num
+    end
+  end
+
+  defp dbl_min(sign), do: %Decimal{sign: sign, coef: 22_250_738_585_072_014, exp: -324}
+  defp zero(sign), do: %Decimal{sign: sign, coef: 0, exp: 0}
+  defp dbl_max(sign), do: %Decimal{sign: sign, coef: 17_976_931_348_623_158, exp: 292}
+
   if Version.compare(System.version(), "1.3.0") == :lt do
     defp integer_to_charlist(string), do: Integer.to_char_list(string)
   else

test/decimal_test.exs

@@ -79,6 +79,8 @@ defmodule DecimalTest do
     assert Decimal.parse("a") == :error
     assert Decimal.parse("test") == :error
     assert Decimal.parse("e0") == :error
+
+    assert Decimal.parse("1e-d") == {d(1, 1, 0), "e-d"}
   end
 
   test "nan?/1" do

test/test_helper.exs

@@ -12,4 +12,22 @@ defmodule TestMacros do
       Decimal.new(unquote(str))
     end
   end
+
+  defmacro dbl_min(sign) do
+    quote do
+      %Decimal{sign: unquote(sign), coef: 22_250_738_585_072_014, exp: -324}
+    end
+  end
+
+  defmacro zero(sign) do
+    quote do
+      %Decimal{sign: unquote(sign), coef: 0, exp: 0}
+    end
+  end
+
+  defmacro dbl_max(sign) do
+    quote do
+      %Decimal{sign: unquote(sign), coef: 17_976_931_348_623_158, exp: 292}
+    end
+  end
 end