From 82815646e66d9379730d7a4fd269aa876b528720 Mon Sep 17 00:00:00 2001
From: Michael Uvarov <arcusfelis@gmail.com>
Date: Tue, 4 Aug 2015 15:33:21 +0200
Subject: [PATCH] Add return_tail option

---
 src/jsx_config.erl  |  5 +++++
 src/jsx_config.hrl  |  1 +
 src/jsx_decoder.erl | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/src/jsx_config.erl b/src/jsx_config.erl
index a7cf3de..92a958b 100644
--- a/src/jsx_config.erl
+++ b/src/jsx_config.erl
@@ -65,6 +65,8 @@ parse_config([dirty_strings|Rest], Config) ->
     parse_config(Rest, Config#config{dirty_strings=true});
 parse_config([multi_term|Rest], Config) ->
     parse_config(Rest, Config#config{multi_term=true});
+parse_config([return_tail|Rest], Config) ->
+    parse_config(Rest, Config#config{return_tail=true});
 %% retained for backwards compat, now does nothing however
 parse_config([repeat_keys|Rest], Config) ->
     parse_config(Rest, Config);
@@ -155,6 +157,7 @@ valid_flags() ->
         unescaped_jsonp,
         dirty_strings,
         multi_term,
+        return_tail,
         repeat_keys,
         strict,
         stream,
@@ -196,6 +199,7 @@ config_test_() ->
                     unescaped_jsonp = true,
                     dirty_strings = true,
                     multi_term = true,
+                    return_tail = true,
                     strict_comments = true,
                     strict_commas = true,
                     strict_utf8 = true,
@@ -209,6 +213,7 @@ config_test_() ->
                     escaped_strings,
                     unescaped_jsonp,
                     multi_term,
+                    return_tail,
                     repeat_keys,
                     strict,
                     stream,
diff --git a/src/jsx_config.hrl b/src/jsx_config.hrl
index 9b5e025..be619c0 100644
--- a/src/jsx_config.hrl
+++ b/src/jsx_config.hrl
@@ -9,6 +9,7 @@
     strict_single_quotes = false        :: boolean(),
     strict_escapes = false              :: boolean(),
     stream = false                      :: boolean(),
+    return_tail = false                 :: boolean(),
     uescape = false                     :: boolean(),
     unescaped_jsonp = false             :: boolean(),
     error_handler = false               :: false | jsx_config:handler(),
diff --git a/src/jsx_decoder.erl b/src/jsx_decoder.erl
index 0f03975..07dce72 100644
--- a/src/jsx_decoder.erl
+++ b/src/jsx_decoder.erl
@@ -1129,6 +1129,8 @@ done(<<?solidus, ?star, Rest/binary>>, Handler, Stack, Config) ->
     comment(Rest, Handler, done, [multicomment|Stack], Config);
 done(<<?solidus>>, Handler, Stack, Config) ->
     incomplete(done, <<?solidus>>, Handler, Stack, Config);
+done(Bin, {_Handler, State}, _Stack, #config{return_tail=true}) ->
+     {with_tail,State, Bin};
 done(<<>>, {Handler, State}, [], Config=#config{stream=true}) ->
     incomplete(done, <<>>, {Handler, State}, [], Config);
 done(<<>>, {_Handler, State}, [], _Config) -> State;
@@ -1938,4 +1940,38 @@ custom_incomplete_handler_test_() ->
     ].
 
 
+return_tail_test_() ->
+    [
+        {"return_tail with tail", ?_assertEqual(
+            {with_tail,[{}],<<"3">>},
+            jsx:decode(<<"{} 3">>, [return_tail])
+        )},
+        {"return_tail without tail", ?_assertEqual(
+            {with_tail,[{}],<<"">>},
+            jsx:decode(<<"{}">>, [return_tail])
+        )},
+        {"return_tail with trimmed whitespace", ?_assertEqual(
+            {with_tail,[{}],<<"">>},
+            jsx:decode(<<"{} ">>, [return_tail])
+        )},
+        {"return_tail and streaming", ?_assertEqual(
+            {with_tail,[{}],<<"3">>},
+            begin
+                {incomplete, F} = jsx:decode(<<"{">>, [return_tail, stream]),
+                F(<<"} 3">>)
+            end
+        )},
+        {"return_tail and streaming", ?_assertEqual(
+            {with_tail,[{}],<<"">>},
+            begin
+                %% In case of infinite stream of objects a user does not know
+                %% when to call F(end_stream).
+                %% So, return_tail overwrites conservative stream end.
+                %% This means that we don't need to call end_stream explicitly.
+                {incomplete, F} = jsx:decode(<<"{">>, [return_tail, stream]),
+                F(<<"}">>)
+            end
+        )}
+    ].
+
 -endif.