Optimize ExpressionFieldPath and give better semantics

2 files changed, 12 insertions, 8 deletions

diff --git a/src/mongo/dbtests/documentsourcetests.cpp b/src/mongo/dbtests/documentsourcetests.cpp
index e4dc5519f73..4ce3c9e2385 100644
--- a/src/mongo/dbtests/documentsourcetests.cpp
+++ b/src/mongo/dbtests/documentsourcetests.cpp
@@ -1389,11 +1389,14 @@ namespace DocumentSourceTests {
             }
         };
 
-        /** A missing nested object within an array is not supported. */
-        class MissingObjectWithinArray : public InvalidOperationBase {
+        /** A missing nested object within an array returns an empty array. */
+        class MissingObjectWithinArray : public CheckResultsBase {
             void populateData() {
                 client.insert( ns, BSON( "_id" << 0 << "a" << BSON_ARRAY( 1 ) ) );
-                client.insert( ns, BSON( "_id" << 1 << "a" << BSON_ARRAY( 0 ) ) );
+                client.insert( ns, BSON( "_id" << 1 << "a" << BSON_ARRAY( BSON("b" << 1) ) ) );
+            }
+            string expectedResultSetString() {
+                return "[{_id:0,a:[1]},{_id:1,a:[{b:1}]}]";
             }
             BSONObj sortSpec() { return BSON( "a.b" << 1 ); }
         };
diff --git a/src/mongo/dbtests/expressiontests.cpp b/src/mongo/dbtests/expressiontests.cpp
index 9f7ad2c0305..f93d2fc391a 100644
--- a/src/mongo/dbtests/expressiontests.cpp
+++ b/src/mongo/dbtests/expressiontests.cpp
@@ -1068,7 +1068,7 @@ namespace ExpressionTests {
         public:
             void run() {
                 intrusive_ptr<Expression> expression = ExpressionFieldPath::create( "a.b" );
-                assertBinaryEqual( fromjson( "{'':[null]}" ),
+                assertBinaryEqual( fromjson( "{'':[]}" ),
                                    toBson( expression->evaluate
                                           ( fromBson( fromjson( "{a:[null]}" ) ) ) ) );
             }            
@@ -1079,7 +1079,7 @@ namespace ExpressionTests {
         public:
             void run() {
                 intrusive_ptr<Expression> expression = ExpressionFieldPath::create( "a.b" );
-                assertBinaryEqual( fromjson( "{'':[undefined]}" ),
+                assertBinaryEqual( fromjson( "{'':[]}" ),
                                    toBson( expression->evaluate
                                           ( fromBson( fromjson( "{a:[undefined]}" ) ) ) ) );
             }            
@@ -1090,8 +1090,9 @@ namespace ExpressionTests {
         public:
             void run() {
                 intrusive_ptr<Expression> expression = ExpressionFieldPath::create( "a.b" );
-                ASSERT_THROWS( expression->evaluate( fromBson( fromjson( "{a:[1]}" ) ) ),
-                               UserException );
+                assertBinaryEqual( fromjson( "{'':[]}" ),
+                                   toBson( expression->evaluate
+                                          ( fromBson( fromjson( "{a:[1]}" ) ) ) ) );
             }            
         };
 
@@ -1111,7 +1112,7 @@ namespace ExpressionTests {
         public:
             void run() {
                 intrusive_ptr<Expression> expression = ExpressionFieldPath::create( "a.b" );
-                assertBinaryEqual( fromjson( "{'':[9,null,undefined,20]}" ),
+                assertBinaryEqual( fromjson( "{'':[9,20]}" ),
                                     toBson( expression->evaluate
                                            ( fromBson( fromjson
                                                       ( "{a:[{b:9},null,undefined,{g:4},{b:20},{}]}"