CmdIDs

- Migrated util.cpp compressIds to CmdIDs::compressIds, as this is the only
  place it is used.

src/commands/CmdIDs.cpp

@@ -31,7 +31,6 @@
 #include <Filter.h>
 #include <main.h>
 #include <text.h>
-#include <util.h>
 #include <i18n.h>
 #include <CmdIDs.h>
 
@@ -73,6 +72,61 @@ int CmdIDs::execute (std::string& output)
   return 0;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// The vector must be sorted first.  This is a modified version of the run-
+// length encoding algorithm.
+//
+// This function converts the vector:
+//
+//   [1, 3, 4, 6, 7, 8, 9, 11]
+//
+// to ths string:
+//
+//   1,3-4,6-9,11
+//
+std::string CmdIDs::compressIds (const std::vector <int>& ids)
+{
+  std::stringstream result;
+
+  int range_start = 0;
+  int range_end = 0;
+
+  for (unsigned int i = 0; i < ids.size (); ++i)
+  {
+    if (i + 1 == ids.size ())
+    {
+      if (result.str ().length ())
+        result << ",";
+
+      if (range_start < range_end)
+        result << ids[range_start] << "-" << ids[range_end];
+      else
+        result << ids[range_start];
+    }
+    else
+    {
+      if (ids[range_end] + 1 == ids[i + 1])
+      {
+        ++range_end;
+      }
+      else
+      {
+        if (result.str ().length ())
+          result << ",";
+
+        if (range_start < range_end)
+          result << ids[range_start] << "-" << ids[range_end];
+        else
+          result << ids[range_start];
+
+        range_start = range_end = i + 1;
+      }
+    }
+  }
+
+  return result.str ();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 CmdCompletionIds::CmdCompletionIds ()
 {

src/commands/CmdIDs.h

@@ -35,6 +35,9 @@ class CmdIDs : public Command
 public:
   CmdIDs ();
   int execute (std::string&);
+
+private:
+  std::string compressIds (const std::vector <int>&);
 };
 
 class CmdCompletionIds : public Command