From c466c7b91578ff3bca2bf52eb7c1542499db38a7 Mon Sep 17 00:00:00 2001
From: Olav Frengstad <olav@fwt.no>
Date: Sat, 3 Oct 2015 05:49:41 +0200
Subject: [PATCH] Add support for encoding '+-infinity'

Erlang can't process the float that is equivialant of Javascripts Infinity
(Number.(POSITIVE,NEGATIVE)_INFINITY) which essentially is the max- and
minimum floating point.

Since there is no concept of a minimum value both are atoms.  This means
you can compare any number to '+infinity" and it will always be larger;
however '-infinity' will also be larger than any number.
---
 src/bson_binary.erl |  9 +++++++--
 test/bson_tests.erl | 17 ++++++++++++++++-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/bson_binary.erl b/src/bson_binary.erl
index 49e3719..16c7971 100644
--- a/src/bson_binary.erl
+++ b/src/bson_binary.erl
@@ -71,6 +71,8 @@ put_field(N, {javascript, {}, Code}) -> <<?put_tagname(13, N), (put_string(Code)
 put_field(N, {javascript, Env, Code}) -> <<?put_tagname(15, N), (put_closure(Code, Env))/binary>>;
 put_field(N, {mongostamp, Inc, Time}) -> <<?put_tagname(17, N), ?put_int32(Inc), ?put_int32(Time)>>;
 put_field(N, UnixTime = {_, _, _}) -> <<?put_tagname(9, N), (put_unixtime(UnixTime))/binary>>;
+put_field(N, '+infinity') -> <<?put_tagname(1, N), 0, 0, 0, 0, 0, 0, 240, 127>>;
+put_field(N, '-infinity') -> <<?put_tagname(1, N), 0, 0, 0, 0, 0, 0, 240, 255>>;
 put_field(N, V) when is_float(V) -> <<?put_tagname(1, N), ?put_float(V)>>;
 put_field(N, V) when is_binary(V) -> <<?put_tagname(2, N), (put_string(V))/binary>>;
 put_field(N, V) when is_tuple(V) -> <<?put_tagname(3, N), (put_document(V))/binary>>;
@@ -84,8 +86,11 @@ put_field(N, V) -> erlang:error(bad_bson, [N, V]).
 
 %% @private
 get_field(<<1:8, _/binary>>, _, Bin1, _) ->
-  <<?get_float(N), Bin2/binary>> = Bin1,
-  {N, Bin2};
+  case Bin1 of
+    <<0, 0, 0, 0, 0, 0, 240, 127, Bin2/binary>> -> {'+infinity', Bin2};
+    <<0, 0, 0, 0, 0, 0, 240, 255, Bin2/binary>> -> {'-infinity', Bin2};
+    <<?get_float(N), Bin2/binary>>              -> {N, Bin2}
+  end;
 get_field(<<2:8, _/binary>>, _, Bin1, _) ->
   get_string(Bin1);
 get_field(<<3:8, _/binary>>, _, Bin1, map) ->
diff --git a/test/bson_tests.erl b/test/bson_tests.erl
index 5fbc64b..893e425 100644
--- a/test/bson_tests.erl
+++ b/test/bson_tests.erl
@@ -145,4 +145,19 @@ maps_flattering_test() ->
       <<"personal.country.domen">> => <<"su">>,
       <<"email">> => <<"test@test.su">>
     },
-  ?assertEqual(FlattenMap, Result).
\ No newline at end of file
+  ?assertEqual(FlattenMap, Result).
+
+infinity_test() ->
+  Encoded = <<16#2b, 16#00, 16#00, 16#00, 16#01, 16#2b, 16#69, 16#6e, 16#66,
+              16#69, 16#6e, 16#69, 16#74, 16#79, 16#00, 16#00, 16#00, 16#00,
+              16#00, 16#00, 16#00, 16#f0, 16#7f, 16#01, 16#2d, 16#69, 16#6e,
+              16#66, 16#69, 16#6e, 16#69, 16#74, 16#79, 16#00, 16#00, 16#00,
+              16#00, 16#00, 16#00, 16#00, 16#f0, 16#ff, 16#00>>,
+
+  ?assertEqual(
+    {{<<"+infinity">>, '+infinity', <<"-infinity">>, '-infinity'}, <<>>},
+    bson_binary:get_document(Encoded)),
+
+  Doc = #{<<"+infinity">> => '+infinity', <<"-infinity">> => '-infinity'},
+  Encoded2 = bson_binary:put_document(Doc),
+  ?assertEqual(Encoded, Encoded2).