SERVER-7172 Allow init() to be called more than once in field parsing (for reuse).

2 files changed, 15 insertions, 0 deletions

diff --git a/src/mongo/db/field_ref.cpp b/src/mongo/db/field_ref.cpp
index 8c74b478312..c3dbc47ed5d 100644
--- a/src/mongo/db/field_ref.cpp
+++ b/src/mongo/db/field_ref.cpp
@@ -25,6 +25,10 @@ namespace mongo {
             return;
         }
 
+        if (_size != 0) {
+            clear();
+        }
+
         // We guarantee that accesses through getPart() will be valid while 'this' is. So we
         // take a copy. We're going to be "chopping" up the copy into c-strings.
         _fieldBase.reset(new char[dottedField.size()+1]);
diff --git a/src/mongo/db/field_ref_test.cpp b/src/mongo/db/field_ref_test.cpp
index e84a9d1158a..cdf4aa7ad92 100644
--- a/src/mongo/db/field_ref_test.cpp
+++ b/src/mongo/db/field_ref_test.cpp
@@ -66,6 +66,17 @@ namespace {
         ASSERT_EQUALS(fieldRef.dottedField(), field);
     }
 
+    TEST(Normal, ParseTwice) {
+        string field = "a";
+        FieldRef fieldRef;
+        for (int i = 0; i < 2; i++) {
+            fieldRef.parse(field);
+            ASSERT_EQUALS(fieldRef.numParts(), 1U);
+            ASSERT_EQUALS(fieldRef.getPart(0), field);
+            ASSERT_EQUALS(fieldRef.dottedField(), field);
+        }
+    }
+
     TEST(Normal, MulitplePartsVariable) {
         const char* parts[] = {"a", "b", "c", "d", "e"};
         size_t size = sizeof(parts)/sizeof(char*);