Extract join function

- use join function for std::vector<std::string> from libshared
- add join function for std::set<std::string>
- add joinQuotedIfNeeded for std::set<std::string> and std::vector<std::string>
- add unit tests
- These functions could be replaced with templates and moved to libshared.

src/commands/CmdReport.cpp

@@ -84,14 +84,7 @@ int CmdReport (
 
   rules.set ("temp.report.start", filter.range.start.toEpoch () > 0 ? filter.range.start.toISO () : "");
   rules.set ("temp.report.end",   filter.range.end.toEpoch ()   > 0 ? filter.range.end.toISO ()   : "");
-  std::string combinedTags;
-  for (auto& tag : filter.tags ())
-  {
-    if (combinedTags != "")
-      combinedTags += ",";
-    combinedTags += quoteIfNeeded (tag);
-  }
-  rules.set ("temp.report.tags", combinedTags);
+  rules.set ("temp.report.tags", joinQuotedIfNeeded (",", filter.tags ()));
   rules.set ("temp.version", VERSION);
 
   std::stringstream header;

src/commands/CmdSummary.cpp

@@ -105,13 +105,7 @@ int CmdSummary (
       if (track.range.is_open () && day <= Datetime ())
         today.end = Datetime ();
 
-      std::string tags = "";
-      for (auto& tag : track.tags ())
-      {
-        if (tags != "")
-          tags += ", ";
-        tags += tag;
-      }
+      std::string tags = join(", ", track.tags());
 
       if (ids)
         table.set (row, 3, format ("@{1}", track.id), colorID);
@@ -156,11 +150,7 @@ int CmdSummary (
 
       if (filter.tags ().size ())
       {
-        std::vector <std::string> tags;
-        for (auto& tag : filter.tags ())
-          tags.push_back (quoteIfNeeded (tag));
-
-        std::cout << " tagged with " << join (", ", tags);
+        std::cout << " tagged with " << joinQuotedIfNeeded (", ", filter.tags ());
       }
 
       std::cout << ".\n";

src/commands/CmdTag.cpp

@@ -95,10 +95,7 @@ int CmdTag (
     // Feedback.
     if (rules.getBoolean ("verbose"))
     {
-      std::cout << "Added";
-      for (auto& tag : tags)
-        std::cout << ' ' << quoteIfNeeded (tag);
-      std::cout << " to @" << id << '\n';
+      std::cout << "Added " << joinQuotedIfNeeded (" ", tags) << " to @" << id << '\n';
     }
   }
 

src/commands/CmdUntag.cpp

@@ -94,10 +94,7 @@ int CmdUntag (
 
     if (rules.getBoolean ("verbose"))
     {
-      std::cout << "Removed";
-      for (auto& tag : tags)
-        std::cout << ' ' << quoteIfNeeded (tag);
-      std::cout << " from @" << id << '\n';
+      std::cout << "Removed " << joinQuotedIfNeeded (" ", tags) << " from @" << id << '\n';
     }
   }