data: Added merge function for merging ranges

src/data.cpp

@@ -30,6 +30,7 @@
 #include <Datetime.h>
 #include <Duration.h>
 #include <timew.h>
+#include <algorithm>
 #include <iostream>
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -430,6 +431,44 @@ std::vector <Interval> flatten (
   return all;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// Simply merges a vector of ranges, without data loss.
+static bool rangeCompare (Range left, Range right)
+{
+  return left.start < right.start;
+}
+
+std::vector <Range> merge (
+  const std::vector <Range>& ranges)
+{
+  // Short cut.
+  if (ranges.size () < 2)
+    return ranges;
+
+  std::vector <Range> sorted {ranges};
+  std::sort (sorted.begin (), sorted.end (), rangeCompare);
+
+  unsigned int cursor = 0;
+  int merges = 0;
+  for (unsigned int i = 0; i < sorted.size (); ++i)
+  {
+    if (cursor && sorted[cursor - 1].overlap (sorted[i]))
+    {
+      sorted[cursor - 1] = sorted[cursor - 1].combine (sorted[i]);
+      ++merges;
+    }
+    else
+    {
+      ++cursor;
+    }
+  }
+
+  if (merges)
+    sorted.resize (ranges.size () - merges);
+
+  return sorted;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Subset both ranges and additions by limits, and combine.
 std::vector <Range> addRanges (

src/timew.h

@@ -45,6 +45,7 @@ std::vector <Interval>  subset            (const Interval&, const std::vector <I
 std::vector <Range>     subset            (const Range&, const std::vector <Range>&);
 std::vector <Interval>  subset            (const Range&, const std::vector <Interval>&);
 std::vector <Interval>  flatten           (const Interval&, const std::vector <Range>&);
+std::vector <Range>     merge             (const std::vector <Range>&);
 std::vector <Range>     addRanges         (const Range&, const std::vector <Range>&, const std::vector <Range>&);
 std::vector <Range>     subtractRanges    (const std::vector <Range>&, const std::vector <Range>&);
 Range                   outerRange        (const std::vector <Interval>&);