wsd: better empty string operations

Change-Id: Ic14efcaa8a1c345b875c27446b16f51740c55efa
Signed-off-by: Ashod Nakashian <ashod.nakashian@collabora.co.uk>

common/SigUtil.cpp

@@ -64,7 +64,7 @@ static std::atomic<bool> ForwardSigUsr2Flag(false); //< Flags to forward SIG_USR
 #endif
 
 static size_t ActivityStringIndex = 0;
-static std::string ActivityHeader = "";
+static std::string ActivityHeader;
 static std::array<std::string, 16> ActivityStrings;
 static bool UnattendedRun = false;
 #if !MOBILEAPP

kit/ChildSession.cpp

@@ -2725,7 +2725,7 @@ bool ChildSession::updateBlockingCommandStatus(const StringVector& tokens)
         sendTextFrameAndLogError("error: cmd=lockstatus kind=failure");
         return false;
     }
-    std::string blockedCommands = "";
+    std::string blockedCommands;
     if (restrictedStatus == "true")
         blockedCommands += CommandControl::RestrictionManager::getRestrictedCommandListString();
     if (lockStatus == "true")

tools/Replay.hpp

@@ -328,7 +328,7 @@ public:
         std::string out = msg;
 
         if (tokens.equals(0, "tileprocessed"))
-            out = ""; // we do this accurately below
+            out.clear(); // we do this accurately below
 
         else if (tokens.equals(0, "load")) {
             std::string url = tokens[1];

tools/map.cpp

@@ -370,7 +370,7 @@ static void dumpDiff(const AddrSpace &space,
                              (str != "[anon]") &&
                              (str != "[stack]");
                 if (!haveAnnots)
-                    str = "";
+                    str.clear();
                 else
                     map->bumpPointerCountInUnshared();
             }

wsd/Admin.cpp

@@ -844,7 +844,7 @@ std::string Admin::getLogLines()
             lineCount = (int)lines.size();
         }
 
-        line = ""; // Use the same variable to include result.
+        line.clear(); // Use the same variable to include result.
         // Newest will be on top.
         for (int i = lineCount - 1; i >= 0; i--)
         {

wsd/AdminModel.cpp

@@ -219,7 +219,7 @@ std::string AdminModel::getAllHistory() const
         separator1 = ",";
     }
     oss << "], \"expiredDocuments\" : [";
-    separator1 = "";
+    separator1.clear();
     for (const auto& ed : _expiredDocuments)
     {
         oss << separator1;

wsd/COOLWSD.cpp

@@ -1923,7 +1923,7 @@ private:
         fonts.clear();
         // Clear the saved ETag of the remote font configuration file so that it will be
         // re-downloaded, and all fonts mentioned in it re-downloaded and fed to ForKit.
-        _eTagValue = "";
+        _eTagValue.clear();
         COOLWSD::sendMessageToForKit("exit");
     }
 
@@ -2743,7 +2743,7 @@ void COOLWSD::innerInitialize(Application& self)
                 LOG_INF("Your support key is valid for " << validDays << " days");
                 COOLWSD::MaxConnections = 1000;
                 COOLWSD::MaxDocuments = 200;
-                COOLWSD::OverrideWatermark = "";
+                COOLWSD::OverrideWatermark.clear();
             }
         }
     }

wsd/ClientSession.cpp

@@ -592,7 +592,7 @@ bool ClientSession::_handleInput(const char *buffer, int length)
     }
     else if (tokens.equals(0, "load"))
     {
-        if (getDocURL() != "")
+        if (!getDocURL().empty())
         {
             sendTextFrameAndLogError("error: cmd=load kind=docalreadyloaded");
             return false;
@@ -1189,14 +1189,14 @@ bool ClientSession::loadDocument(const char* /*buffer*/, int /*length*/,
             std::string encodedUserId;
             Poco::URI::encode(getUserId(), "", encodedUserId);
             oss << " authorid=" << encodedUserId;
-            encodedUserId = "";
+            encodedUserId.clear();
             Poco::URI::encode(COOLWSD::anonymizeUsername(getUserId()), "", encodedUserId);
             oss << " xauthorid=" << encodedUserId;
 
             std::string encodedUserName;
             Poco::URI::encode(getUserName(), "", encodedUserName);
             oss << " author=" << encodedUserName;
-            encodedUserName = "";
+            encodedUserName.clear();
             Poco::URI::encode(COOLWSD::anonymizeUsername(getUserName()), "", encodedUserName);
             oss << " xauthor=" << encodedUserName;
         }

wsd/FileServerUtil.cpp

@@ -202,7 +202,7 @@ std::string FileServerRequestHandler::uiDefaultsToJSON(const std::string& uiDefa
     Poco::JSON::Object presentationDefs;
     Poco::JSON::Object drawingDefs;
 
-    uiMode = "";
+    uiMode.clear();
     uiTheme = "light";
     savedUIState = "true";
     StringVector tokens(StringVector::tokenize(uiDefaults, ';'));