Merge pull request diffblue#2039 from peterschrammel/fix-duplicate-msg-json-ui

Fix duplicate message output in json-ui

Author: peterschrammel

regression/cbmc/json1/main.c

@@ -0,0 +1,6 @@
+int main()
+{
+  unsigned x;
+  assert(x==0);
+  return 0;
+}

regression/cbmc/json1/test.desc

@@ -0,0 +1,12 @@
+CORE
+main.c
+--json-ui --stop-on-fail
+activate-multi-line-match
+EXIT=10
+SIGNAL=0
+\[\n  \{\n    "program": "CBMC .*"\n  \},\n  \{\n    "messageText": "CBMC .*",\n    "messageType": "STATUS-MESSAGE"\n  \},\n  \{\n    "messageText": "Parsing main\.c",\n    "messageType": "STATUS-MESSAGE"\n  \},
+\]\n  \},\n  \{\n    "messageText": "VERIFICATION FAILED",\n    "messageType": "STATUS-MESSAGE"\n  \},\n  \{\n    "cProverStatus": "failure"\n  \}\n\]
+--
+--
+The purpose of this test is to catch duplicate output of messages and
+output of empty messages on flushing the message stream.

src/util/message.h

@@ -209,7 +209,8 @@ class messaget
 
     mstreamt &operator << (const xmlt &data)
     {
-      *this << eom; // force end of previous message
+      if(this->tellp() > 0)
+        *this << eom; // force end of previous message
       if(message.message_handler)
       {
         message.message_handler->print(message_level, data);
@@ -219,7 +220,8 @@ class messaget
 
     mstreamt &operator << (const json_objectt &data)
     {
-      *this << eom; // force end of previous message
+      if(this->tellp() > 0)
+        *this << eom; // force end of previous message
       if(message.message_handler)
       {
         message.message_handler->print(message_level, data);
@@ -243,7 +245,8 @@ class messaget
     /// Returns a reference to the top-level JSON array stream
     json_stream_arrayt &json_stream()
     {
-      *this << eom; // force end of previous message
+      if(this->tellp() > 0)
+        *this << eom; // force end of previous message
       return message.message_handler->get_json_stream();
     }
 

src/util/ui_message.cpp

@@ -294,11 +294,6 @@ void ui_message_handlert::json_ui_msg(
   const std::string timestamp = time->stamp();
   if(!timestamp.empty())
     result["timestamp"] = json_stringt(timestamp);
-
-  // By convention a leading comma is created by every new array entry.
-  // The first entry is generated in the constructor and does not have
-  //  a trailing comma.
-  std::cout << ",\n" << result;
 }
 
 void ui_message_handlert::flush(unsigned level)