Anticipate Lane Changes

include/util/group_by.hpp

@@ -0,0 +1,40 @@
+#ifndef OSRM_GROUP_BY
+#define OSRM_GROUP_BY
+
+#include <algorithm>
+#include <utility>
+
+namespace osrm
+{
+namespace util
+{
+
+// Runs fn on consecutive items in sub-ranges determined by pred.
+//
+// Example:
+//   vector<int> v{1,2,2,2,3,4,4};
+//   group_by(first, last, even, print);
+//   >>> 2,2,2
+//   >>> 4,4
+//
+// Note: this mimics Python's itertools.groupby
+template <typename Iter, typename Pred, typename Fn>
+Fn group_by(Iter first, Iter last, Pred pred, Fn fn)
+{
+    while (first != last)
+    {
+        first = std::find_if(first, last, pred);
+        auto next = std::find_if_not(first, last, pred);
+
+        (void)fn(std::make_pair(first, next));
+
+        first = next;
+    }
+
+    return fn;
+}
+
+} // ns util
+} // ns osrm
+
+#endif