po-lite: improve help & error output formatting

The following cosmetic changes are made:

 - tidy output of error/warning reporting without location context

 - help: fix minimum spacing between options and help text

 - help: add blank line before options whose text collide with help text
   to improve general readability

 - help: widen the options column to reduce number of overlaps



git-svn-id: http://wg11.sc29.org/svn/repos/MPEG-I/Part5-PointCloudCompression/TM/TMC3/trunk@1314 94298a81-5874-47c9-aab8-bfb24faeed7f

dependencies/program-options-lite/program_options_lite.cpp

@@ -54,13 +54,21 @@ namespace df
     ostream& ErrorReporter::error(const string& where)
     {
       is_errored = 1;
-      cerr << where << " error: ";
+      if (!where.empty())
+        cerr << where << " error: ";
+      else
+        cerr << "Error: ";
+
       return cerr;
     }
 
     ostream& ErrorReporter::warn(const string& where)
     {
-      cerr << where << " warning: ";
+      if (!where.empty())
+        cerr << where << " warning: ";
+      else
+        cerr << "Warning: ";
+
       return cerr;
     }
 
@@ -165,7 +173,7 @@ namespace df
         max_width = max(max_width, (unsigned) line.tellp());
       }
 
-      unsigned opt_width = min(max_width+2, 28u + pad_short) + 2;
+      unsigned opt_width = min(max_width+2, 7+28u + pad_short) + 2;
       unsigned desc_width = columns - opt_width;
 
       /* second pass: write out formatted option and help text.
@@ -187,10 +195,12 @@ namespace df
           continue;
         }
         size_t currlength = size_t(line.tellp());
-        if (currlength > opt_width)
+        if (currlength >= opt_width)
         {
           /* if option text is too long (and would collide with the
-           * help text, split onto next line */
+           * help text, split onto next line and ensure a gap after
+           * the previous option to increase readability */
+          cout << endl;
           line << endl;
           currlength = 0;
         }

dependencies/program-options-lite/program_options_lite.h

@@ -64,8 +64,8 @@ namespace df
     {
       ErrorReporter() : is_errored(0) {}
       virtual ~ErrorReporter() {}
-      virtual std::ostream& error(const std::string& where);
-      virtual std::ostream& warn(const std::string& where);
+      virtual std::ostream& error(const std::string& where = "");
+      virtual std::ostream& warn(const std::string& where = "");
       bool is_errored;
     };