Repo created

libs/base/set_operations.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+// Similar to set_difference(), but if element is present n times in the first sequence and once in
+// the second sequence, all n copies are filtered, insted of one.
+template <typename Iter1T, typename Iter2T, typename OutIterT, typename LessT>
+OutIterT SetDifferenceUnlimited(Iter1T beg1, Iter1T end1, Iter2T beg2, Iter2T end2, OutIterT out, LessT lessCompare)
+{
+  while (beg1 != end1 && beg2 != end2)
+  {
+    if (lessCompare(*beg1, *beg2))
+    {
+      *out = *beg1;
+      ++beg1;
+      ++out;
+    }
+    else if (lessCompare(*beg2, *beg1))
+    {
+      ++beg2;
+    }
+    else
+    {
+      ++beg1;
+      // This is the difference between set_difference and this function:
+      // In set_difference the commented line should be present.
+      // ++beg2;
+    }
+  }
+  return std::copy(beg1, end1, out);
+}