From 5d5d2b9a4b412d9ab4f1a889621864ca47ba2d9b Mon Sep 17 00:00:00 2001
From: Anton Kalyaev <a.kalyaev@fun-box.ru>
Date: Thu, 16 Apr 2015 14:09:57 +0300
Subject: [PATCH] correctly handle empty lists

before this commit it was throwing an error:

```
{error,
   {index_for_non_list,{1,[]}},
   [{ej,get_value,2,[{file,"src/ej.erl"},{line,157}]}
```
---
 src/ej.erl            | 8 ++++++++
 test/ej_alt_test.erl  | 7 ++++++-
 test/menu.alt_terms   | 4 +++-
 test/menu.json        | 3 ++-
 test/menu.terms       | 4 +++-
 test/widget.alt_terms | 1 +
 test/widget.json      | 1 +
 test/widget.terms     | 1 +
 8 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/src/ej.erl b/src/ej.erl
index 6433c32..45e287a 100644
--- a/src/ej.erl
+++ b/src/ej.erl
@@ -139,6 +139,14 @@ get_value(Key, []) when is_binary(Key) ->
     undefined;
 get_value(Key, null) when is_binary(Key) ->
     undefined;
+get_value(first, []) ->
+    undefined;
+get_value(last, []) ->
+    undefined;
+get_value(Index, []) when is_integer(Index) ->
+    undefined;
+get_value({select, _KeyValue}, []) ->
+    {from_select, []};
 get_value(first, [H|_T]) ->
     H;
 get_value(last, List=[_H|_T]) ->
diff --git a/test/ej_alt_test.erl b/test/ej_alt_test.erl
index e5f816e..8ea0fc8 100644
--- a/test/ej_alt_test.erl
+++ b/test/ej_alt_test.erl
@@ -24,6 +24,9 @@ ej_alt_test_() ->
             ?_assertEqual(4, ej:get({"widget", "values", 4}, Widget)),
             ?_assertEqual(1, ej:get({"widget", "values", first}, Widget)),
             ?_assertEqual(5, ej:get({"widget", "values", last}, Widget)),
+            ?_assertEqual(undefined, ej:get({"widget", "keys", first}, Widget)),
+            ?_assertEqual(undefined, ej:get({"widget", "keys", last}, Widget)),
+            ?_assertEqual(undefined, ej:get({"widget", "keys", 2}, Widget)),
             ?_assertEqual({[{<<"id">>, 5}]},
                           ej:get({<<"objects">>, last}, ObjList)),
             ?_assertEqual({[{<<"id">>, 1}]},
@@ -65,7 +68,9 @@ ej_alt_test_() ->
               ComplexBeginning = {{select, {"match", "me"}}},
               ?assertMatch([{_}, {_}], ej:get(ComplexBeginning, Data)),
               ComplexBeginningDeeper = {{select, {"match", "me"}}, "match"},
-              ?assertMatch([<<"me">>, <<"me">>], ej:get(ComplexBeginningDeeper, Data))
+              ?assertMatch([<<"me">>, <<"me">>], ej:get(ComplexBeginningDeeper, Data)),
+              PathAgainstEmptyList = {"menu", "popup", "titleitem", {select, {"value", "Title"}}},
+              ?assertMatch([], ej:get(PathAgainstEmptyList, Menu))
             end},
           {"ej:get with multi-level array matching",
            fun() ->
diff --git a/test/menu.alt_terms b/test/menu.alt_terms
index bf974b9..9dcd178 100644
--- a/test/menu.alt_terms
+++ b/test/menu.alt_terms
@@ -6,4 +6,6 @@
          [{[{<<"value">>,<<"New">>},{<<"onclick">>,<<"CreateNewDoc()">>}]},
           {[{<<"value">>,<<"Open">>},{<<"onclick">>,<<"OpenDoc()">>}]},
           {[{<<"value">>,<<"Close">>},
-            {<<"onclick">>,<<"CloseDoc()">>}]}]}]}}]}}]}.
+            {<<"onclick">>,<<"CloseDoc()">>}]}]},
+        {<<"titleitem">>,
+         []}]}}]}}]}.
diff --git a/test/menu.json b/test/menu.json
index 2689d94..e85c284 100644
--- a/test/menu.json
+++ b/test/menu.json
@@ -6,7 +6,8 @@
         {"value": "New", "onclick": "CreateNewDoc()"},
         {"value": "Open", "onclick": "OpenDoc()"},
         {"value": "Close", "onclick": "CloseDoc()"}
-      ]
+      ],
+      "titleitem": []
     }
   }}
 
diff --git a/test/menu.terms b/test/menu.terms
index d3e8ba3..a2a9378 100644
--- a/test/menu.terms
+++ b/test/menu.terms
@@ -14,4 +14,6 @@
                         {<<"onclick">>,<<"OpenDoc()">>}]},
                    {struct,
                        [{<<"value">>,<<"Close">>},
-                        {<<"onclick">>,<<"CloseDoc()">>}]}]}]}}]}}]}.
+                        {<<"onclick">>,<<"CloseDoc()">>}]}]},
+                 {<<"titleitem">>,
+                  []}]}}]}}]}.
diff --git a/test/widget.alt_terms b/test/widget.alt_terms
index b021c50..84dc522 100644
--- a/test/widget.alt_terms
+++ b/test/widget.alt_terms
@@ -1,6 +1,7 @@
 {[{<<"widget">>,
    {[{<<"version">>,<<"1">>},
      {<<"values">>,[1,2,3,4,5]},
+     {<<"keys">>,[]},
      {<<"debug">>,<<"on">>},
      {<<"window">>,
       {[{<<"title">>,<<"Sample Konfabulator Widget">>},
diff --git a/test/widget.json b/test/widget.json
index a043687..d9efe38 100644
--- a/test/widget.json
+++ b/test/widget.json
@@ -1,6 +1,7 @@
 {"widget": {
   "version": "1",
   "values": [1,2,3,4,5],
+  "keys": [],
   "debug": "on",
   "window": {
     "title": "Sample Konfabulator Widget",
diff --git a/test/widget.terms b/test/widget.terms
index f5f5f01..37ac66b 100644
--- a/test/widget.terms
+++ b/test/widget.terms
@@ -1,6 +1,7 @@
 {struct,[{<<"widget">>,
           {struct,[{<<"version">>,<<"1">>},
                    {<<"values">>,[1,2,3,4,5]},
+                   {<<"keys">>,[]},
                    {<<"debug">>,<<"on">>},
                    {<<"window">>,
                     {struct,[{<<"title">>,<<"Sample Konfabulator Widget">>},